JPH09293538A - Lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery in which discharging capacity is enhanced, and safety and cost performance are superior. SOLUTION: A lithium ion secondary battery is composed of a positive electrode, a negative electrode, nonaqueous electrolyte, and a vessel containing them in a sealed state. In the lithium ion secondary battery, the positive electrode contains positive electrode active material which is formed by electrochemically discharging lithium ions from a positive electrode active material precursor which is mainly composed of manganese oxide and the lithium ion containing amount of which is heightened by the electrochemical insertion of the lithium ions in the vessel. The negative electrode contains negative electrode active material which is formed by inserting the lithium ions discharged from the positive electrode active material precursor into a negative electrode active material mainly composed of metal oxide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lithium ion secondary battery.

[0002]

2. Description of the Related Art Conventionally, Li has been used as a positive electrode active material for a lithium ion secondary battery characterized by a voltage of 4 V class and a high capacity.
As compounds effective for inserting and releasing ions, LiMn ₂ O ₄ having a spinel structure, LiMnO ₂ having a rock salt structure, and Li
CoO ₂ , LiCo _1-X Ni _x O ₂ , or LiNi
O ₂ is commonly used. Among them, the rock salt type structure LiCoO ₂ is advantageous in that it has a high voltage and a high electric capacity, but it suffers from the problems of high manufacturing cost due to a small supply amount of cobalt raw material and environmental safety problems of waste batteries. Contains.

Japanese Patent Laid-Open No. 3-147276 discloses a secondary battery in which LiMn ₂ O ₄ having a spinel structure, which is made of manganese as a raw material, in which a large amount of the raw material is supplied, is low in cost, and has good environmental suitability is used as a positive electrode material. Is proposed. But,
In general, LiMn ₂ O ₄ has a charge capacity (Li release amount) per volume smaller than that of LiCoO ₂ by 10 to 20%. Therefore, when a battery is prepared by combining this with a high capacity negative electrode active material, a positive electrode It is necessary to increase the volume of the active material used, and as a result, there is a problem that the amount of the negative electrode active material incorporated in the battery is limited and a sufficient electric capacity cannot be obtained.

In Japanese Patent Laid-Open No. 4-147573, Li is disclosed.
Li _{1 + x} Mn, which has a larger charge capacity than Mn ₂ O _4.
By synthesizing ₂ O ₄ (x> 0) and incorporating this into a positive electrode active material and a negative electrode active material such as a carbonaceous material capable of being doped and dedoped with lithium as a positive electrode and a negative electrode of a battery, respectively, A non-aqueous electrolyte secondary battery with improved battery capacity has been proposed.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the lithium ion secondary battery described in Japanese Patent No. 573, Li _{1 + x} Mn ₂ O used for forming an active material of a positive electrode.
₄ is manufactured in advance by a method of introducing Li by electrolytic reduction or chemical synthesis before being incorporated into a product battery, and the obtained active material is easily oxidized at a low potential and is unstable, Supplying as an active material for batteries presents storage and handling problems. Therefore,
The inventors of the present invention have found that stable LiMn ₂ O as a starting material.
While using ₄ , this was electrochemically discharged in a closed system in the battery prior to the charge / discharge operation, and was temporarily subjected to Li _{1 + x} Mn.
A method of electrolytic reduction to ₂ O ₄ was examined. Therefore, an object of the present invention is to provide a lithium ion secondary battery having improved discharge capacity, safety and cost performance.

[0006]

The present invention is, firstly, a lithium ion secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a container accommodating them in a hermetically sealed state. A positive electrode active material in which lithium ions are electrochemically inserted in the container to electrochemically release lithium ions from a positive electrode active material precursor containing lithium manganese oxide having a high lithium ion content as a main component. A negative electrode active material formed by inserting lithium ions released from the positive electrode active material precursor into a negative electrode active material precursor containing a metal oxide as a main component. It is a lithium-ion secondary battery characterized by including it.

Secondly, the present invention relates to a lithium ion secondary battery precursor comprising a positive electrode precursor, a negative electrode precursor, a non-aqueous electrolyte, and a container containing them in a hermetically sealed state. The body contains a positive electrode active material precursor mainly composed of lithium manganese oxide having an increased lithium ion content, in which lithium ions are electrochemically inserted in the container, and the negative electrode precursor Is a lithium-ion secondary battery precursor characterized by containing a negative electrode active material precursor containing a metal oxide as a main component.

Thirdly, the present invention relates to a lithium ion secondary battery precursor comprising a positive electrode precursor raw material, a negative electrode precursor and a non-aqueous electrolyte, and a container containing these in a hermetically sealed state. The precursor raw material contains lithium manganese oxide as a main component, and the precursor raw material is joined in a state where metal lithium or a lithium alloy is electrically short-circuited in the vicinity of the precursor raw material, and the negative electrode precursor raw material is metal oxide. The lithium ion secondary battery precursor is characterized in that it contains a negative electrode active material precursor containing a substance as a main component.

Fourthly, the present invention relates to a lithium ion secondary battery precursor comprising a positive electrode precursor raw material, a negative electrode precursor and a non-aqueous electrolyte, and a container accommodating them in a sealed state. The precursor raw material contains lithium manganese oxide as a main component, and the negative electrode precursor contains a negative electrode active material precursor containing a metal oxide as a main component. There is also a lithium ion secondary battery precursor characterized in that a lithium alloy is joined in a state where it can be electrically connected.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below. 1) The positive electrode active material precursor is Li _{1 + x} Mn ₂ O ₄ (0.3 <
A substance having a tetragonal crystal structure represented by a composition formula of x <1), wherein the positive electrode active material is represented by a composition formula of Li _y Mn ₂ O ₄ (however, 0.3 <y <1). It is a substance having a cubic crystal structure. 2) The positive electrode has Li _x CoO ₂ (0.5 <
x ≦ 1) or Li _x Co _y Ni _z O ₂ (0.5 <x ≦
1, 0 ≦ x ≦ 1, and 0 ≦ z ≦ 1). 3) The positive electrode active material precursor is formed by electrochemical self-discharge between the lithium manganese oxide and metallic lithium or a lithium-containing alloy in the container.

4) The positive electrode active material precursor utilizes an external electric circuit in the container between the lithium manganese oxide and metallic lithium or a lithium-containing alloy carried in proximity to the negative electrode active material precursor. It is formed by all electrochemical discharges. 5) The negative electrode active material is an amorphous composite metal oxide containing tin in which lithium ions are inserted as a main component. 6) The negative electrode active material precursor is an amorphous mixed metal oxide containing tin as a main component, and its composition formula is SnL _k O _z (L
Represents at least one atom selected from the group consisting of Al, B, P, Si, an atom of an element belonging to Groups 1 to 3 of the periodic table, and a halogen atom; and k and z are each 0.2 ≦ or less. or a Sn _d Q _1-d L _k O _z (Q represents a transition metal atom; L represents Al, B, P and Si). , At least one atom selected from the group consisting of an atom of an element belonging to Groups 1 to 3 of the periodic table and a halogen atom; and d,
k and z are 0.1 ≦ d ≦ 0.9 and 0.2 ≦ k, respectively.
It represents a numerical value that satisfies ≦ 2 and 1 ≦ z ≦ 6. ).

7) The ratio of the amount of lithium released at the time of battery discharge to the amount of lithium inserted into the negative electrode active material precursor is 1 / using the composition formula x of the positive electrode active material precursor in discharging up to a battery voltage of 3V. (1 + x) or less. 8) The positive electrode active material precursor is a lithium manganese oxide having a spinel type crystal structure.

The lithium ion secondary battery of the present invention uses a positive electrode active material precursor containing a lithium manganese composite oxide as a main component and a precursor raw material. What is preferably used as the lithium manganese composite oxide is a lithium-containing manganese oxide having a spinel type crystal structure that gives a high voltage. The spinel-type oxide has a crystal structure represented by the general formula A (B ₂ ) O ₄ , in which oxygen anions are arranged in a cubic close-packed form in the crystal, and thus tetrahedral and octahedral Occupies part of the face and apex of. Depending on the distribution state of the cation “A”, A (B ₂ ) O _{4 is changed} to normal spinel, B
(A, B) O ₄ is called reverse spinel. Impinges on these intermediate states, the structure of the _{A x B y (A 1-} x B 1-y) O 4 is also present as a spinel. LiMn ₂ O ₄ is a typical example of a lithium manganese oxide having a normal spinel structure. In this structure, half the Mn cations are trivalent and half are tetravalent. Λ, also known as active material
-MnO ₂ is a defective spinel structure in which lithium is removed from the crystal structure of LiMn ₂ O ₄ , as shown in US Pat. No. 4,246,253, in which all Mn cations are contained. It is tetravalent. The lithium manganese oxide positive electrode active material used in the present invention may be either a normal spinel type, an inverse spinel type, or a defect-free spinel structure or a defect non-stoichiometric spinel structure.

The lithium manganese oxide used in the present invention (that is, the lithium-containing manganese oxide) has a general formula of Li _{1 + x} [Mn _2-y ] O ₄ (0 ≦ x <1.
7, oxides represented by 0 ≦ y <0.7).
Examples of this oxide include those represented by Li ₄ Mn ₅ O ₁₂ or Li [Li _1/3 Mn _5/3 ] O ₄ in the spinel structure representation. In addition, the compounds represented by the following formulas are also included in the range of the above general formula (the structural formulas include those represented by the integer multiple or the decimal multiple of the general formula). Li ₄ Mn ₄ O ₉ Li ₂ MnO ₃ Li ₅ Mn ₄ O ₉ Li ₄ Mn ₅ O ₁₂

Other preferable examples of the spinel-type lithium-containing manganese oxide that can be used in the present invention include:
General formula Li _1-x [Mn _2-y ] O ₄ (0 <x <1.0, 0
The oxides represented by ≦ y <0.5) can be mentioned. Among these, particularly preferred is the general formula Li _1-x
[Mn _2-y ] O ₄ (0.20 <x <1.0, 0 <y <
It is an oxide represented by 0.2). An example of this oxide is L, which is a non-stoichiometric spinel compound disclosed in JP-A-4-240117.
i ₂ Mn ₅ O ₁₁ or Li _{1-x in the} spinel structure display
[Mn _2-y ] O ₄ (x = 0.273, y = 0.182)
Are represented. In addition, examples of other preferable oxides include the general formula Li _1-x [Mn _2-y ] O ₄ (0 <x
≦ 0.20, 0 <y <0.4).
An example of this oxide is Li ₂ Mn ₄ O ₉ . In addition, compounds represented by the following formulas are also included in the range of the above-mentioned general formula Li _1-x [Mn _2-y ] _d O ₄ included). Li ₄ Mn _16.5 O ₃₅ Li ₂ Mn _7.5 O ₁₆ Li _0.7 MnO ₄

The lithium manganese oxide, which is a precursor raw material for the positive electrode active material before being filled in the battery of the present invention, can be prepared by reacting a lithium salt with a manganese salt or manganese oxide in a solid phase at a high temperature according to a conventional method. can get. When using lithium carbonate and manganese dioxide as raw materials, the firing temperature is 3
50 ° C to 900 ° C, preferably 350 ° C to 500 ° C
And the firing time is 8 to 48 hours. Also,
As a lithium salt, low melting point lithium nitrate (melting point 261
(° C) is used, the firing temperature is from 300 ° C to 900 ° C.
And preferably 300 to 500 ° C. The manganese oxide includes λ-MnO ₂ , electrolytically prepared MnO ₂ (EMD), and chemically prepared MnO.
₂ (CMD), and mixtures thereof can optionally be used. Other sources of lithium include lithium
A manganese composite oxide (for example, Li ₂ Mn ₄ O ₉ or the like) can be used. In this case, lithium
The manganese composite oxide is mixed with a manganese raw material such as manganese dioxide and fired in the range of 350 ° C to 500 ° C.

In the positive electrode active material precursor raw material of the present invention, in addition to the above compounds as a lithium manganese composite oxide,
LiMnO _{2 having} a rock salt structure and L having a spinel structure
Li _{1 + x} M formed by inserting Li ions into iMn ₂ O ₄
n ₂ O ₄ (0 ≦ x ≦ 0.5) or LiMn ₂ O ₄ to L
Li _1-x Mn ₂ O formed by chemical desorption of i ions
₄ (0 ≦ x ≦ 0.5) may be added.

As the positive electrode active material precursor raw material, lithium manganese oxide can be mixed with other transition metal composite oxides as a sub active material. A preferred oxide that can be mixed as a secondary active material is Li _x CoO ₂ (0.5 <x ≦ 1), which is also a high-capacity and high-voltage type lithium cobalt composite oxide. In addition, lithium cobalt nickel composite oxide, Li
_x Co _y Ni _z O ₂ (0.5 <x ≦ 1, 0 ≦ y ≦ 1, 0
<Z ≦ 1) is also a preferred oxide. Besides LiCoO ₂ , a solid solution containing various transition metals, non-transition metals, alkali elements, rare earth elements, etc. in addition to Co can also be used as a side active material. A preferred mixing ratio of the positive electrode active material precursor to the lithium manganese oxide is, for example, when using lithium cobalt oxide as the sub-active material,
The weight ratio of lithium cobalt oxide to lithium manganese oxide is in the range of 2/8 to 9/1 and 3/7 to 7 /
The range of 3 is more preferable. The positive electrode active material precursor raw material of the present invention is preferably a crystalline compound, but may be amorphous. It may also be a mixture of a crystalline compound and an amorphous compound.

In the lithium ion secondary battery of the present invention, as the negative electrode active material used in combination with the positive electrode active material, a negative electrode active material precursor that does not substantially contain Li ions is previously prepared in the product battery container. Is a high-capacity active material obtained by a method of activating the active material by inserting into a low-potential active material. Here, the phrase "substantially free of Li ions" means that mobile Li ions are not included. When used in combination with a high-capacity type positive electrode active material obtained by activation according to the method described below according to the present invention, a decrease in discharge capacity caused by inefficiency of initial charge / discharge that occurs during activation of the negative electrode active material The problem can be solved and the battery capacity can be improved.

A preferred negative electrode active material precursor is a composite metal oxide containing tin. The composite metal oxide containing tin is preferably amorphous, and particularly preferably one represented by the following general formula (1) or (2). (1) SnL _k O _z Here, L is Al, B, P, Si, and the periodic table 1 to 3
At least one atom selected from the group consisting of atoms of elements belonging to the group and halogen atoms is shown. k and z
Are numerical values that satisfy 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6, respectively.

(2) Sn _d Q _1-d L _k O _z Here, L, k, and z have the same meanings as described above. Q represents a transition metal, preferably V, Ti, F
represents e, Mn, Co, Ni, Zn, W, or Mo. d is a numerical value that satisfies 0.1 ≦ d ≦ 0.9.
Among the general formula (1), L is preferably Al, B,
P, an atom of an element belonging to Groups 1 to 3 of the periodic table, and two or more kinds of atoms selected from the group consisting of halogen atoms, and k and z are 0.2 ≦ k ≦ 2 and 1 respectively. ≤
The oxide represented by the numerical value satisfying z ≦ 6 is particularly preferable, and the oxide represented by the following general formula (3) is particularly preferable.

(3) SnT _h R _i O _z Here, T represents at least one atom selected from the group consisting of Al, B and P. R is the first to third periodic table
At least one atom selected from the group consisting of atoms of elements belonging to the group and halogen atoms is shown. h, i and z are 0.2 ≦ h ≦ 2, 0.01 ≦ i ≦ 1, respectively
It is a numerical value that satisfies 0.2 ≦ h + i ≦ 2 and 1 ≦ z ≦ 6.

The negative electrode active material precursor is preferably mainly amorphous when it is incorporated into a battery (that is, when the product battery is filled in a container). The term "amorphous" used herein means an X-ray diffraction method using CuKα rays and a 2θ value of 20 ° to 4 °
It is a substance that gives a broad scattering band having an apex at 0 °, and may have a crystalline diffraction line in the scattering band. Preferably, the strongest intensity among the crystalline diffraction lines observed at a 2θ value of 40 ° to 70 ° is 20 ° to 4 at a 2θ value.
It is 500 times or less, more preferably 100 times or less, particularly preferably 5 times or less, and most preferably crystalline diffraction of the intensity of the diffraction line at the apex of the broad scattering band seen at 0 ° or less. It has no lines.

In the lithium secondary battery of the present invention, the positive electrode
The negative electrode active material used in combination with the active material has a high discharge capacity.
It is characterized by being extremely large, but these are in front of the negative electrode active material.
It can be obtained by inserting Li into the precursor.
Examples of the negative electrode active material precursor that can be used in the present invention are as follows.
Shown below. SnSi_0.8P_0.2O_3.1, SnSi_0.5A
l_0.1B_0.2P_0.2O_1.95, SnSi_0.8B
_0.2O_2.9, SnSi_0.8Al_0.2O_2.9, SnSi
_0.6Al_0.1B_0.2O_1.65, SnSi_0.3Al_0.1P
_0.6O_2.25, SnSi_0.4B_0.2P_0.4O_2.1, SnS
i_0.6Al_0.1B_0.5O_2.1, SnB_0.5P_0.5O_Three,
SnAl_{0. Three} B_0.5P_0.2O_2.7, SnK_0.2P
O_3.6, SnRb_0.2Al_0.05P_0.8O_{3. twenty five}, SnAl
_0.3B_0.7O_2.5, SnBa_0.1Al_0.15P
_1.45O_4.7, SnLa_0.1Al_0.1P_0.9O_3.55, Sn
Na_0.1Al_0.05B_0.45O_1.8, SnLi_0.2B_0.5P
_0.5O_3.1, SnCs_0.1B_0.4P_0.4O_2.65, SnB
a_0.1B_0.4P_0.4O_2.7, SnCa_0.1Al_0.15B
_0.45P_0.55O_3.9, SnY_0.1Al_0.3B_0.6P_0.6O
_Four, SnRb_0.2Al_0.1B_0.3P_0.4O_2.7, SnC
s_0.2Al_0.1B_0.3P_0.4O_2.7, SnCs_0.1Al
_0.1B_0.4P_0.4O_2.8, SnK_{0. 1}Cs_0.1B_0.4P
_0.4O_2.7, SnBa_0.1Cs_0.1B_0.4P
_0.4O_2.75, SnMg_0.1K_0.1B_0.4P_0.4O_2.75,
SnCa_0.1K_0.1B_0.4P_0.5O_Three, SnBa_0.1K
_0.1Al_0.1B_0.3P_0.4O_2.75, SnMg_0.1Cs
_0.1Al_{0. 1}B_0.3P_0.4O_2.75, SnCa_0.1K_0.1
Al_0.1B_0.3P_0.4O_2.75, SnMg_0.1Rb_0.1A
l_0.1B_0.3P_0.4O_2.75, SnCa_0.1B_0.2P_0.2
F_{0. Two}O_2.6, SnMg_0.1Cs_0.1B_0.4P_0.4F
_0.2O_3.3, SnMg_0.1Al_0.2 B_0.4P_0.4F_0.2
O_2.9, Sn_0.5Mn_0.5Mg_0.1B_0.9O_2.45, Sn
_0.5 Mn_0.5Ca_0.1P_0.9O_3.35, Sn_0.5Ge_0.5
Mg_0.1P_0.9O_3.35, Sn_0.5Fe_0.5Ba_0.1P
_0.9O_3.35, Sn_0.5Fe_0.5Al_0.1B_0.9O_{2. Five},
Sn_0.8Fe_0.2Ca_0.1P_0.9O_3.35, Sn_0.3Fe
_0.7Ba_0.1P_0.9O_3.35, Sn_0.9Mn_0.1Mg_0.1
P_0.9O_3.35, Sn_0.2Mn_0.8Mg_0.1P_0.9 
O_3.35, Sn_0.7Pb_0.3Ca_0.1P_0.9O_3.35, Sn
_0.2Ge_0.8Ba_{0. 1}P_0.9O_3.35, Sn_1.0 Al_0.1 
B_0.5 P_0.5 O_3.15, Sn_1.0 Cs_0.1 B_{0. Five} P_0.5 O
_3.05, Sn_1.0 Cs_0.1 Al_0.1 B_0.5 P_0.5 O_3.20,
Sn_1.0 Cs_0.1 Al_0.3 B_0.5 P_0.5 O_3.50, Sn
_1.0 Cs_0.1 Ge_0.05Al_0.1 B_0.5 P_0.5 O_3.30, S
n_1.0 Cs_0.1 Ge_0.05Al_0.3 B_0.5 P_0.5 O_3.60

The negative electrode active material used in the present invention is obtained by electrochemically preliminarily inserting lithium ions into the above negative electrode active material precursor in the container of the product battery. In the method of electrochemically inserting lithium ions, the positive electrode active material precursor of the present invention is used as a counter electrode, and the negative electrode side is subjected to cathodic polarization in a battery made of a non-aqueous electrolyte containing a lithium salt to carry out lithium charging. Ions are inserted into the negative electrode active material precursor. In particular, the negative electrode active material used in the present invention is the amount of lithium released from the negative electrode when the battery is discharged to 3 V with respect to the amount of lithium inserted into the negative electrode active material precursor during the initial charging (activation) process. Ratio (F) of the positive electrode active material precursor composition Li1 + x Mn ₂ O ₄ x of F ≦ 1 /
It is preferable that it is represented by (1 + x).

The Li insertion amount (preliminary insertion amount) into the negative electrode active material precursor is not particularly limited, but may be inserted up to 0.05 V with respect to, for example, a Li—Al alloy (80-20 wt%). preferable. Furthermore, it is preferable to insert up to 0.1 V, and particularly preferably up to 0.15 V. At this time, the equivalent of pre-insertion of lithium ions depends on the potential and is 3 to 10 equivalents, so the capacity of pre-insertion is usually a high value of 500 mAh / g. The positive electrode active material precursor raw material on the positive electrode side and the amount of Li metal (or Li alloy) used for electrochemically inserting lithium ions into the positive electrode active material precursor raw material are determined corresponding to this capacity. Specifically, the total equivalent of releasable Li ions that can be generated from the positive electrode active material precursor raw material and Li metal (or Li alloy) is 0.
It is desirable to set it to be 5 to 2 times.

The average particle size of the positive electrode active material used in the lithium ion secondary battery of the present invention, its precursor, its raw material, the negative electrode active material and its precursor is preferably 0.03 to 50 μm,
Particularly, the average particle diameter is preferably 0.1 μm to 20 μm. The average particle diameter as used herein is a mode diameter indicating the most frequent point, and is an average value of values visually observed in an electron micrograph or a value measured by a particle size distribution measuring device. The specific surface area of these active materials is preferably in the range of 0.1 to 50 m ² / g. The specific surface area of the positive electrode active material and its precursor is particularly preferably 1 to 10 m ² / g.

Next, in the present invention, a method for activating the positive electrode active material precursor filled in the product battery container will be described. The activation referred to in the present invention means that the active material has high discharge energy and is charged to a potential at which reversible charge and discharge can be performed. The activation of the positive electrode means that the positive electrode active material has a high discharge capacity due to the release of Li ions and is charged to a sufficiently high potential capable of reversible charge and discharge. In the present invention, when LiMn ₂ O ₄ is used for charging / discharging the positive electrode, this sufficiently high potential means 3.8 V or more with respect to Li ions, preferably 4.
At a potential of 2 V or higher, at a potential of 4.2 V or higher, Li ion in the structure of LiMn ₂ O ₄ is released at 0.9 equivalent or more (at 4.3 V, 0.95 equivalent or more). However, the amount of released Li ions (that is, the charge capacity) when charging is started from the structure of LiMn ₂ O ₄
When converted to the weight of the active material, for example, LiC
It is 10 to 20% smaller than oO ₂ . As the configuration of the lithium-ion secondary battery of the present invention, as the negative electrode active material,
When a metal oxide having a large capacity for precharging (insertion of Li ions) necessary for activation of the precursor is used, L of the positive electrode is used.
It is necessary to increase the i-ion emission amount particularly. Therefore, when LiMn ₂ O ₄ is used as a raw material for producing a positive electrode active material, reduced Li 1 + x Mn ₂ O ₄ having a structure in which Li ions are further inserted into LiMn ₂ O ₄ is used as a precursor before activation. It is necessary to increase the amount of Li ion released to the negative electrode active material precursor by using the same.

Li _{1 + x} M of the positive electrode active material precursor before activation
Since n ₂ O ₄ is unstable in storage, it is disclosed in JP-A-4-4-1.
In the lithium secondary battery having the conventional structure as described in Japanese Patent No. 47573, it was necessary to synthesize it in another battery immediately before activation and then incorporate it in the container of the product battery. . In the present invention, the preparation of the positive electrode active material precursor is carried out by using lithium manganese oxide and L
A method of self-discharging both of i metal or Li alloy as a reaction starting material on the positive electrode, or lithium manganese oxide on the positive electrode and Li metal or L on the negative electrode.
It is characterized in that it is performed by utilizing a method of discharging the i alloy through an external circuit.

The following method may be mentioned as a typical method for preparing the precursor of the positive electrode active material by discharging in the container of the product battery. 1) A method in which a Li metal or a Li alloy is joined to a positive electrode current collector supporting a positive electrode active material containing a lithium manganese oxide so as to be electrically short-circuited, and this is reacted in an electrolytic solution containing Li ions. . 2) Li on the surface of the active material precursor layer of the positive electrode current collector carrying the positive electrode active material precursor containing lithium manganese oxide.
A method of joining thin films of a metal or a Li alloy and reacting them in an electrolytic solution containing Li ions. 3) A thin film of Li metal or Li alloy is formed on a surface protective layer such as a conductive material coated on the active material precursor layer of the positive electrode current collector carrying the positive electrode active material precursor containing lithium manganese oxide. A method of joining and reacting them in an electrolytic solution containing Li ions.

4) Li metal or Li alloy was joined to a negative electrode current collector carrying a negative electrode active material precursor composed of a metal oxide so as to be electrically connected, and this was placed in an electrolyte containing Li ions. How to react with. 5) A thin film of Li metal or Li alloy is bonded to the surface of the active material precursor layer of the negative electrode current collector carrying the negative electrode active material precursor composed of a metal oxide, and this is reacted in an electrolyte solution containing Li. How to make. 6) A thin film of Li metal or Li alloy is formed on a surface protective layer such as a conductive material coated on the surface of the active material precursor layer of the negative electrode current collector supporting the negative electrode active material precursor composed of a metal oxide. A method of joining and reacting this in an electrolytic solution containing Li. During this discharge process, part of the lithium on the negative electrode is simultaneously inserted into the negative electrode active material precursor of the negative electrode by self-discharge. That is, by activation, the lithium carried on the negative electrode is simultaneously inserted into both the positive electrode active material precursor and the negative electrode active material precursor, and is finally consumed entirely.

Of the above methods, the preferred methods are 2 and 3.
And the method of 3 is particularly preferable. That is, 3
In the method of (1), an intermediate layer having appropriate conductivity is inserted between the lithium manganese oxide and the Li metal (or lithium alloy), so that the rapid reaction between the lithium manganese oxide and the Li metal is relaxed. The heat generated by the reaction can be suppressed. Composition formula of precursor Li _{1 + x} Mn ₂
In O ₄ , x is preferably 0.3 <x <1. For high capacity active materials such as LiCoO ₂ ,
The preferred composition of the precursor for the lithium manganese oxide to be dominant in terms of capacity per volume of charge is 0.5 <x
≦ 0.9. Further, in order to activate the positive electrode active material precursor into a charged state positive electrode active material having a high discharge capacity, at least Li _y Mn is obtained as a result of electrochemical release of Li ions from the precursor. ₂ O ₄ (0 <y <
It is necessary to obtain an active material having a composition of 0.3).
Furthermore, in order to increase the discharge capacity, Li _y Mn ₂ O
It is preferable to activate so as to have a composition of ₄ (0 <y <0.2).

[0033] In the present invention, when the secondary battery after activation completion performs cycles of charge and discharge, the composition of the lithium manganese oxide in the positive electrode active material, the need to maintain high potential, Liy Mn ₂ O ₄ (0 <y <1), and the composition of the positive electrode active material related to charging / discharging is Liy Mn ₂
It never becomes O ₄ (1 <y). Further, a preferable range of the composition of the positive electrode active material involved in charge / discharge of the secondary battery of the present invention is Liy Mn ₂ O ₄ (0 <y <0.9).

As the lithium material used for the reaction between the lithium manganese oxide and the Li metal or the Li alloy, Li metal having a purity of 95% or more is preferable. The lithium metal is preferably in the form of a thin film (foil) having a uniform thickness, and the thickness thereof is preferably 10 to 100 μm. As an alloy of lithium and another metal, Li-Al, Li-Al-Mn system,
Li-Al-Mg system, Li-Al-Sn system, Li-Al
-In, Li-Al-Cd type | system | group etc. can be used. Li metal or Li alloy is pressure-bonded onto the active material precursor layer or the protective layer coated on the active material precursor layer in an atmosphere of dry gas.

In the lithium secondary battery of the present invention, other negative electrode active material can be used together. Examples of the negative electrode active material that can be used in combination include lithium metal, the above lithium alloy, and the like, and carbonaceous compounds capable of inserting and extracting lithium ions or lithium metal. The purpose of using the lithium metal or lithium alloy together is to insert lithium ions into the battery, and does not utilize the dissolution / precipitation reaction of lithium metal or the like as the battery reaction.

The battery precursor used in the production of the lithium ion secondary battery in the present invention (that is, the positive electrode active material precursor, the negative electrode active material precursor, and the electrolyte solution incorporated in the product battery) is a production control. The positive electrode active material precursor raw material and the negative electrode active material precursor described above are incorporated in the battery container of No. 1 above, but other than these configurations, a conventionally known configuration can be used. That is, for example, in the case of a cylindrical battery precursor, an electrode (positive and negative electrode) sheet, an electrolytic solution, a separator and the like are incorporated. Figure 1 attached
FIG. 1 is a schematic cross-sectional view of an example (cylindrical battery) of the lithium-ion secondary battery of the present invention. As shown in FIG. 1, the cylindrical battery includes a positive electrode sheet 8 and a negative electrode sheet 9 that form electrodes in a battery can (battery container) 11 (also serving as a negative electrode terminal), a separator 10 for separating both electrodes, and The electrolytic solution 13 is contained in a hermetically sealed state by a battery lid 12 (also serving as a positive electrode terminal) via a gasket. A safety valve 14 is provided in the battery. The positive electrode sheet 9 and the negative electrode sheet 9 are laminated with the separator 10 in between and wound in a spiral shape.

The positive and negative electrode sheets are made of a mixture (sometimes referred to as a mixture or an electrode mixture) obtained by adding a conductive agent, a binder, a filler or the like to each of the precursors. It can be obtained by applying a dispersion liquid dispersed in a solvent onto each current collector.

The conductive agent may be any electron conductive material that does not undergo a chemical change in the constructed battery.
Usually, natural graphite (scaly graphite, flake graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber or metal (copper, nickel, aluminum, silver, etc.) powder, metal fiber or A conductive material such as a polyphenylene derivative can be included as one type or a mixture thereof. A combination of graphite and acetylene black is particularly preferred. The amount added is not particularly limited, but is preferably in the range of 1 to 50% by weight, and particularly preferably in the range of 2 to 30% by weight. In the case of carbon or graphite, it is particularly preferable to be in the range of 2 to 15% by weight.

The binder is usually starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone,
Tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, polybutadiene, fluoro rubber,
Polysaccharides such as polyethylene oxide, thermoplastic resins, polymers having rubber elasticity, and the like are used alone or as a mixture thereof. The amount of the binder added is preferably in the range of 2 to 30% by weight.

As the filler, any fibrous material can be used as long as it does not cause a chemical change in the constructed battery. Usually, fibers such as olefin-based polymers such as polypropylene and polyethylene, glass, and carbon are used. Although the amount of the filler is not particularly limited,
It is preferably in the range of ˜30% by weight. The mixture of the positive electrode and the negative electrode may contain an electrolytic solution or a supporting salt. For example, a method of incorporating an ion conductive polymer, nitromethane, or an electrolytic solution is known.

Any current collector may be used as long as it is an electron conductor that does not cause a chemical change in the constructed battery.
For example, for the positive electrode, in addition to stainless steel, nickel, aluminum, titanium, calcined carbon, etc. as the material, carbon, nickel on the surface of aluminum or stainless steel,
Those treated with titanium or silver, the negative electrode, in addition to stainless steel, nickel, copper, titanium, aluminum, calcined carbon, etc. as a material, the surface of copper or stainless steel is treated with carbon, nickel, titanium or silver. ), An Al-Cd alloy, etc. are used. The surface of these materials can be oxidized and used. These materials include foils, films, sheets, nets (lath bodies), punched sheets, porous bodies, foams,
It is used in the form of a molded product of a fiber group. The thickness is not particularly limited, but usually 5 to 100 μm is used.

The electrolytic solution (electrolyte solution) is composed of an aprotic organic solvent and a lithium salt (electrolyte) soluble in the solvent. Examples of the organic solvent include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane,
Tetrahydrofuran, 2-methyltetrahydrofuran,
Dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate,
Examples thereof include phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, and 1,3-propanesartone. These can be used as a mixture of one or more.

Examples of the lithium salt include LiCl
O ₄ , LiBF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , L
_{iCF 3 CO 2, LiAsF 6,} LiSbF 6, LiB
₁₀ Cl ₁₀ , lithium lower aliphatic carboxylate, LiAlC
Examples thereof include l ₄ , LiCl, LiBr, LiI, lithium chloroborane, and lithium tetraphenylborate.
These can be used as a mixture of one or more. In the present invention, LiCF ₃ S is added to a mixed solution of propylene carbonate or ethylene capote and 1,2-dimethoxyethane and / or diethyl carbonate.
O ₃ , LiClO ₄ , LiBF ₄ and / or Li
It is preferable to use an electrolytic solution containing PF ₆ .

The amount of the electrolytic solution to be added to the battery is not particularly limited, but the required amount is adjusted according to the amount of the positive electrode active material (precursor and raw material) and the negative electrode active material (precursor) and the size of the battery. Used. The volume ratio of the solvent is not particularly limited, but in the case of a mixed solution of propylene carbonate or ethylene carbonate to 1,2-dimethoxyethane and / or diethyl carbonate, 0.4 / 0.6 to
0.6 / 0.4 (the mixing ratio when both 1,2-dimethoxyethane and diethyl carbonate are used is 0.4 / 0.
6 to 0.6 / 0.4) is preferable. The concentration of the electrolyte is not particularly limited, but is preferably 0.2 to 3 mol per liter of the electrolytic solution.

The electrolytic solution may contain the following organic solid electrolytes. A polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ionic dissociative group, a mixture of the polymer containing an ionic dissociative group and the aprotic electrolyte solution, and a phosphoric acid ester polymer are effective. is there. Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. Further, a method of using an inorganic and organic solid electrolyte in combination (Japanese Patent Laid-Open No. 60-1768) is also known.

To the lithium ion secondary battery of the present invention, the following compounds may be added to the electrolytic solution for the purpose of improving charge / discharge characteristics. For example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone and N, N′-substituted imidazolidinone, ethylene glycol Dialkyl ether, quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, aluminum trichloride, monomer of conductive polymer electrode active material, triethylenephosphonamide, trialkylphosphine, morpholine, aryl compound having carbonyl group, Hexamethylphosphoric triamide, 4-alkylmorpholine, bicyclic tertiary amine, oil, quaternary phosphonium salt, tertiary sulfonium salt and the like can be mentioned.

Further, in order to make the electrolytic solution nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolytic solution. In addition, carbon dioxide gas can be included in the electrolytic solution in order to provide suitability for high-temperature storage.

As the separator, a thin film having a large ion permeability, a predetermined mechanical strength and an electrically insulating property is used. A sheet or non-woven fabric made of an olefin polymer such as polyethylene or polypropylene, glass fiber or polyethylene is used because of its resistance to organic solvents and hydrophobicity. The pore size of the separator is generally in the range useful for batteries, and usually in the range of 0.01 to 10 μm. Similarly, the thickness of the separator is usually 5 to 300.
It is in the range of μm. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as the separator.

Further, the surface of the positive electrode active material can be modified. For example, a method of treating the surface of the metal oxide with an esterifying agent or a chelating agent, or modifying the surface by coating a surface layer of a conductive polymer, polyethylene oxide, or the like can be mentioned. Similarly, the surface of the negative electrode active material can be modified. Examples thereof include coating with an ion conductive polymer or a polyacetylene layer, or surface treatment with a Li salt.

The shape of the battery can be any of coins, buttons, sheets, cylinders, corners and the like. In the coin or button shape, the electrode mixture is used after being pressed into a pellet shape. In the case of a sheet, a cylinder or a prism, the electrode mixture is used after being applied, dried, dehydrated and pressed on a current collector. The thickness of the coating layer is determined by the size of the battery, but is 10 to 500 in a compressed state after drying.
The range of μm is particularly preferable.

The application of the lithium-ion secondary battery (non-aqueous lithium-ion secondary battery) obtained by the method of the present invention is not particularly limited.
Color notebook type personal computer, black and white notebook type personal computer, pen input type personal computer, pocket type (palmtop) personal computer, notebook type word processor, pocket type word processor, electronic book player, mobile phone, cordless phone handset, pager, handy Terminal, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD player, mini disk player, electric shaver, electronic translator, car phone, transceiver, power tool, electronic organizer, calculator , Memory cards, tape recorders, radios, backup power supplies, memory cards, etc. Other examples include automobiles, electric vehicles, motors, lighting equipment, toys, game machines, road conditioners, irons, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various military purposes and space applications. Further, it can be combined with a solar cell.

[0052]

EXAMPLES The present invention will be described in more detail with reference to the following examples of battery production, but the present invention is not limited to the examples as long as the gist of the invention is not exceeded.

[Synthesis of Negative Electrode Active Material Precursor] (1) SnB _0.5 P _0.5 O ₃ (Compound A-1) SnO (67.4 g), B ₂ O ₃ (17.4 g), Sn
₂ P ₂ O ₇ (102.8 g) was mixed, sufficiently pulverized and mixed in an automatic mortar, filled in an alumina crucible, and baked at 1000 ° C. for 10 hours under an argon gas atmosphere. After firing, quenched in a 100 ° C. / minute rate to obtain a negative electrode active material precursor of a yellow clear glass SnB _0.5 P _{0. 5} O ₃ (Compound A-1). When the X-ray diffraction of the active material was measured, no diffraction line belonging to the crystal structure was detected, and it was found that the active material structure was amorphous. (2) The following negative electrode active material precursor was synthesized by the same method. Sn _1.5 K _0.2 PO _3.5 (Compound A-2) SnAl _0.1 B _0.5 P _0.5 Mg _0.1 F _0.2 O _3.15 (Compound A-3)

[Preparation of Positive Electrode Active Material Precursor (Raw Material)] (1) Li _1.02 Mn ₂ O ₄ (Compound C-1) with Spinel Crystal Structure, Particle Size 5 to 50 μm, BET Surface Area 40 to 70 m ² / g Electrolytically synthesized manganese dioxide (EMD, containing 1 wt% or less of Mn ₂ O ₃ and Mn ₃ O ₄ as impurities and 3 wt% or less of sulfate and water, respectively) and an average particle size of 1 to 10
Li / M was prepared by pulverizing lithium hydroxide to a particle size of μm.
After mixing by dry or wet so that the molar ratio of n is 1.02 / 2, and drying at 100 ° C. for 1 hour, 400 to 6
Heat treatment at 00 ° C. for 3 hours, crush the product again,
It was calcined in air at 00 ° C. for 48 hours. The final fired product was gradually cooled to room temperature at a rate of about 2 ° C./min and pulverized in an automatic mortar. As a result, the obtained particles had a primary particle size of 0.5 μm, and the secondary particles had a particle size of 8 to 8. It was 20 μm (median diameter: 12.5 μm). The BET method surface area was in the range of ² to 4 m ² / g, depending on the grinding conditions. As a result of identifying the structure and composition of the product by ICP and X-ray diffraction, the calcined product was Li _1.02 Mn ₂ O ₄ having a spinel crystal structure. The half-value width of the diffraction peak of 2θ = 36 in X-ray diffraction using Cuα ray is about 0.3, and the intensity thereof is 2θ = 18.6.
The value was 28% with respect to the peak of. The a-axis lattice constant of the crystal was 8.22A. It was also found that a trace amount of LiMnO ₂ was mixed in the fired product. As a result of dispersing 5 g of the baked product in 100 cc of pure water and measuring the pH, it was 8.0.

(2) Li ₂ Mn ₄ O ₉ (Compound C-2)
And Li ₄ Mn ₅ O ₁₂ (compound C-3) except that the firing conditions were one-step firing in air at 650 ° C. for 48 hours, and the mixing ratio (L
by changing the i / Mn ratio), Li ₂ Mn ₄ O
₉ (Compound C-2) and Li ₄ Mn ₅ O ₁₂ (Compound C-3) were synthesized. All of them are crystals having a distorted spinel structure and have a median diameter of Li ₂ Mn ₄
O ₉ was 9 μm, and Li ₄ Mn ₅ O ₁₂ was 20 μm.

(3) LiCoO ₂ (Compound C-4: Positive Electrode Subactive Material) A mixture of Co ₃ O ₄ and Co ₂ O ₃ and lithium carbonate were added to Li.
The mixture was mixed so that the / Co molar ratio was 1.05, and the mixture was baked in air at 600 ° C. for 4 hours and further at 880 ° C. for 8 hours. As a result of grinding the fired product in an automatic mortar, the particles obtained have a median diameter of 6 μm, a BET specific surface area of 0.5 m ² / g, and LiCoO ₂ by X-ray diffraction.
Was identified. The pH of the active material measured by the above method is 1
0.5. (4) LiNi _0.8 Co _0.2 O ₂ (Compound C-5: Positive Electrode Subactive Material) In addition to the raw materials described in (3) above, nickel hydroxide is mixed as a metal source, and the mixture is placed in an oxygen atmosphere at 800 ° C. 48
LiNi _0.8 Co _0.2
To give the O _2.

[Preparation of Electrode Mixture Sheet] (1) Positive Electrode Mixture Sheet 87% by weight of compound C-1 as a raw material for the positive electrode active material precursor, 6% by weight of scaly graphite, 3% by weight of acetylene black, and binding After mixing 3% by weight of an aqueous dispersion of polytetrafluoroethylene as an agent and 1% by weight of sodium polyacrylate, water was added to the mixture and kneaded, and the resulting slurry was applied to both sides of an aluminum film having a thickness of 20 μm. Then, a positive electrode mixture sheet was produced. When the coating sheet was dried and pressed, it was measured and the dry film coating amount was about 3
The coating film thickness was 40 g / m ² , and the thickness was approximately 120 μm. (2) Negative electrode mixture sheet 86% by weight of compound A-1 as a negative electrode active material precursor, 6% by weight of scaly graphite, 3% by weight of acetylene black, and 4% by weight of aqueous dispersion of styrene-butadiene rubber as a binder. % And 1% by weight of carboxymethyl cellulose, water was added to the mixture and kneaded, and the obtained slurry was applied to both sides of a copper film having a thickness of 18 μm,
A negative electrode mixture sheet was produced. When the coated sheet was dried and pressed, and then measured, the dry film coating amount was about 70 g.
/ M ² , and the thickness of the coating film was about 30 μm.

[Production of Cylinder Type Battery] [Comparative Battery 1] The above positive electrode material mixture sheet was cut into a width of 35 mm, and the negative electrode material mixture sheet was cut into a width of 39 mm, and aluminum was applied to the ends of the sheet, respectively. After the nickel lead plate was spot-welded, it was dehydrated and dried at 150 ° C. for 2 hours in dry air having a dew point of −40 ° C. 1, the dehydrated and dried positive electrode mixture sheet (8), a porous propylene film (Celgard 2400) (10) as a separator, the dehydrated and dried negative electrode mixture sheet (9), and These were laminated in the order of the separator (10) and spirally wound with a winding machine. The wound body was housed in a nickel-plated iron bottomed cylindrical battery can (11) (also serving as a negative electrode terminal). In this battery can, 1 mol / l of LiPF 6 as electrolyte solution
₆ (2: 2: 6 (volume ratio) mixed solution of ethylene carbonate, butylene carbonate and dimethyl carbonate) was injected. A battery lid (12) having a positive electrode terminal was caulked through a gasket to produce a cylindrical battery having a diameter of 14 mm and a height of 50 mm. The positive electrode terminal (12) is connected to the positive electrode mixture sheet (8) and the battery can (11) to the negative electrode mixture sheet (9) by a lead terminal in advance, and a safety valve (14) is provided in the battery. It was

[Comparative Batteries 2-5] C-2, C-3, and C-1 and C instead of C-1 as the positive electrode active material precursor.
2: 1 (weight ratio) mixture with C-4 and C-1 and C-
5 and a 2: 1 (weight ratio) mixture was used, and A-2 and A-3 were used instead of A-1 as the negative electrode active material precursor, and these positive electrode mixture sheet and negative electrode mixture sheet were prepared. Batteries were produced in the same manner as in Comparative Battery 1 except that they were wound in arbitrary combination, and Comparative Batteries 2 to 5 having the positive electrode / negative electrode configurations shown in Table 1 were obtained.

[Battery precursors 6 to 10 of the present invention] Thickness 30
A Li metal foil of μm is cut into a width of 20 mm and a length of 320 mm (weight is about 100 mg), and the length direction is 4
After being cut into pieces having a uniform width of mm, the active material layer surfaces on both surfaces of the positive electrode mixture sheet coated with the above-mentioned positive electrode active material precursor raw materials C-1 to 3 in dry air having a dew point of −60 ° C. It was made to adhere using a pressure roller at uniform intervals. Further, the same Li metal foil was cut into a width of 14 mm and a length of 320 mm (about 70 mg in weight), and the above-mentioned positive electrode active material precursor raw material C-
The mixture of 1 and C-4 and the mixture of C-1 and C-5 were applied to the surfaces of the active material layers on both surfaces of the positive electrode mixture sheet using a pressure roller. The positive electrode mixture sheet carrying the Li metal foil in this manner was housed in a battery can in the same manner as in the method for producing the comparative battery described above, and the positive electrode /
Lithium ion secondary battery precursors 6 to 10 according to the present invention as shown in the configuration of the negative electrode were prepared.

[Battery Precursors 11 to 15 of the Present Invention] In the production of the positive electrode mixture sheet, a mixture of scaly graphite and aluminum oxide in a ratio of 1: 4 (weight ratio) is protected on the surface of the active material precursor layer. Except that a layer (average thickness 5 μm) was applied, the same method as the above-mentioned method for producing the electrode mixture sheet was used,
A positive electrode mixture sheet with a surface protective layer coated with various active material precursors was produced. On the surface protective layer of this positive electrode mixture sheet, as in the case of the batteries 6 to 10, L having a thickness of 30 μm was used.
An i metal foil (width 20 mm, length 320 mm, weight approx. 100 mg) was applied. The positive electrode mixture sheet carrying the Li metal foil in this manner was housed in a battery can in the same manner as in the method for producing the comparative battery described above, and the results are shown in Table 1.
Lithium ion secondary battery precursors 11 to 15 according to the present invention having the structure of positive electrode / negative electrode shown in FIG.

[Battery Precursors 16 to 17 of the Present Invention] Conductive carbon is formed to a thickness of 10 μm on both surfaces of an aluminum film (current collector) on the end of the positive electrode mixture sheet on which the active material precursor is not coated. It is vacuum evaporated and has a thickness of 20 on both sides.
A positive electrode mixture sheet carrying Li metal on a current collector was produced by adhering 100 mg of 0 μm Li metal foil using a pressure roller. Using this positive electrode mixture sheet, lithium ion secondary battery precursors 16 to 17 according to the present invention having the positive electrode / negative electrode configurations shown in Table 1 were produced.

[Lithium-ion secondary batteries 6-1 of the present invention
Production of 7] Each of the battery precursors of the present invention incorporating a positive electrode mixture sheet carrying Li metal was subjected to aging at 40 ° C. prior to a charge / discharge test, and self-discharged at the positive electrode site. Then, lithium ions were inserted from the Li metal on the positive electrode mixture sheet into the positive electrode active material precursor. The battery precursors 16 to 17 were aged for 7 days, and the battery precursors 6 to 15 were aged for 1 day.

[Battery Precursors 18-22 of the Invention] Thickness 3
A 5 μm Li metal foil was cut into a width of 20 mm and a length of 320 mm (weight: about 100 mg), and the negative electrode active material precursors A-1 to A-3 were coated in dry air with a dew point of −60 ° C., respectively. It was made to adhere to the surfaces of the active material precursor layers on both sides of the agent sheet using a pressure roller. The negative electrode mixture sheet carrying the Li metal foil in this manner was housed in a battery can in the same manner as in the method for producing the comparative battery described above, and each had the positive electrode / negative electrode configuration shown in Table 1. Lithium ion secondary battery precursors 18 to 22 according to the above were prepared.

[Battery Precursors 23 to 27 of the Present Invention] In the preparation of the negative electrode mixture sheet, a mixture of scaly graphite and aluminum oxide in a ratio of 1: 4 (weight ratio) is protected on the surface of the active material precursor layer. A negative electrode mixture sheet with a surface protective layer was prepared by coating various active material precursors in the same manner except that the layer (average thickness 5 μm) was coated. On the surface protective layer of this sheet, as in the case of the batteries 18 to 22 of the present invention, a Li metal foil having a thickness of 35 μm (width 20 mm, length 32
0 mm, weight approximately 100 mg) was deposited.
The negative electrode mixture sheet carrying the Li metal foil in this manner was housed in a battery can in the same manner as the method for producing the comparative battery described above, and according to the present invention having the positive electrode / negative electrode configurations shown in Table 1, respectively. Lithium ion secondary battery precursors 23 to 27 were produced.

[Battery precursors 28 to 29 of the present invention] 100 mg of a Li metal foil having a thickness of 200 μm on both sides of the copper current collector on the end of the negative electrode mixture sheet on which the active material precursor was not coated.
Was attached using a pressure roller to prepare a negative electrode mixture sheet carrying Li metal on the current collector. Using this negative electrode mixture sheet, lithium ion secondary battery precursors 28 to 29 of the present invention having the positive electrode / negative electrode configurations shown in Table 1 were produced.

[Lithium-ion secondary battery 18 of the present invention]
Production of 29] The above-mentioned battery precursors incorporating the above-mentioned Li metal-supported negative electrode mixture sheet were each left at room temperature for 5 hours, and then an external electrode circuit was installed under a constant current of 0.2 A. After discharging, the open electromotive force of the battery finally becomes 0.
The discharge was performed at a lower current until the voltage reached 2V. Batteries that had been subjected to discharge treatment were then subjected to 4
Aging was carried out at 0 ° C. for 2 days. In this aging step, it was confirmed that all of the Li remaining on the negative electrode was inserted into the negative electrode active material precursor.

[Evaluation of Lithium-Ion Secondary Battery] The lithium-ion secondary battery precursors 6 to 17 of the present invention were charged with a cut-off voltage of 4.2 V, a discharge-end voltage of 2.7 V, and a charge-discharge current of 1.
The charge capacity was evaluated by repeatedly charging and discharging under mA / cm ² . Lithium-ion secondary battery 18-29 of the present invention
Was repeatedly charged and discharged under a charge end voltage of 4.2 V, a discharge end voltage of 2.8 V, and a charge / discharge current density of 1 mA / cm ² , to evaluate the charge capacity.

Table 1 below shows the positive electrode / negative electrode configurations of the comparative battery and the battery of the present invention, and the relationship between the discharge capacity and the discharge average voltage. Table 2 shows the lithium manganese in the positive electrode active material precursor in which the battery was decomposed before the charging operation after the aging was completed and the reaction with Li was completed for a part of the battery precursor having the configuration shown in Table 1. The results of ICP emission analysis and X-ray diffraction analysis of the composition and structure of the oxide and the positive electrode activity when the battery precursor was precharged to 4.2 V for activation and then repeatedly charged and discharged. It shows the composition range of the lithium manganese oxide active material in the material. For these batteries, the activation of the positive electrode was not performed if the active material composition of the lithium manganese oxide was Li
To the extent of depth in the range of _0.05-0.10 Mn ₂ O ₄ were performed. When the activation depth was shallow and the composition range was Li _{> 0.30} Mn ₂ O ₄ , the discharge capacity of the battery was significantly reduced by 30% or more.

[0070]

[Table 1] Table 1 Comparison of battery discharge capacity and average discharge voltage ─────────────────────────────────── ── Battery number Positive electrode active material (Li supported) Negative electrode active material Discharge capacity Discharge voltage Precursor (raw material) Precursor (Ah) (V) ─────────────────── ───────────────── Comparative battery 1 C-1 (none) A-1 0.42 3.652 C-2 (none) A-3 0.43 3. 65 3 C-3 (none) A-2 0.44 3.664 4 C-1 / 4 (none) A-1 0.50 3.55 5 C-1 / 5 (none) A-1 0.53 3.50 ──────────────────────────────────── The present invention battery (supporting positive electrode Li metal) 6 C -1 (on active material layer) A-1 0.50 3.65 C-2 (on active material layer) A-3 0.47 3.658 8 C-3 (on active material layer) A-2 0.49 3.65 9 C-1 / 4 (on active material layer) A -1 0.55 3.55 10 C-1 / 5 (on active material layer) A-1 0.56 3.50 11 C-1 (on protective layer) A-1 0.51 3.66 12 C- 2 (on protective layer) A-3 0.48 3.66 13 C-3 (on protective layer) A-2 0.50 3.66 14 C-1 / 4 (on protective layer) A-1 0.56 3.56 15 C-1 / 5 (on protective layer) A-1 0.56 3.51 16 C-1 (on current collector) A-1 0.49 3.65 17 C-1 / 5 (collection) A-1 0.53 3.50 ───────────────────────────────────── This book Invention battery (negative electrode Li metal supported) 18 C-1 (active material Top) A-1 0.50 3.65 19 C-2 (on active material layer) A-3 0.48 3.65 20 C-3 (on active material layer) A-2 0.49 3.65 21 C-1 / 4 (on active material layer) A-1 0.54 3.552 22 C-1 / 5 (on active material layer) A-1 0.55 3.52 23 C-1 (on protective layer) A-1 0.51 3.65 24 C-2 (on protective layer) A-3 0.47 3.66 25 C-3 (on protective layer) A-2 0.50 3.66 26 C-1 / 4 (on protective layer) A-1 0.55 3.56 27 C-1 / 5 (on protective layer) A-1 0.55 3.50 28 C-1 (on current collector) A-1 0. 48 3.65 29 C-1 / 5 (on current collector) A-1 0.53 3.50 ────────────────────────── ───────────

[0071]

[Table 2] Table 2 ──────────────────────────────────── After the self-discharge reaction of the positive electrode (positive electrode Structure of lithium manganese oxide (before activation) and composition of lithium manganese oxide during charging and discharging ───────────────────────────── ──────── Battery number Composition formula after self-discharge Range of composition during charge and discharge ──────────────────────────── _{───────── 6 Li 1.7 Mn 2 O 4} Li 0.1-0.85 Mn 2 O 4 7 Li 1.6 Mn 2 O 4 Li 0.1-0. 83 Mn 2 O 4 8 Li 1.8 Mn 2 O 4 Li 0.1 _-0.84 Mn ₂ O ₄ 14 Li _1.7 Mn ₂ O ₄ Li _0.1-0.90 Mn ₂ O ₄ 15 Li _1.7 Mn ₂ O ₄ Li _0.1-0.85 Mn ₂ O ₄ 16 Li _1.7 Mn ₂ O ₄ Li _0.1-0.85 Mn ₂ O ₄ 23 Li _1.7 Mn ₂ O ₄ Li _{0.1 -0.86} Mn ₂ O ₄ 24 Li _1.6 Mn ₂ O ₄ Li _0.1-0.83 Mn ₂ O ₄ 25 Li _1.8 Mn ₂ O ₄ Li _0.1-0.85 Mn ₂ O ₄ ─────────────── ──────────────────────

From the results shown in Table 1, a lithium ion secondary battery manufactured in a product battery container using a mixture sheet of a positive electrode active material precursor synthesized from lithium manganese oxide supporting Li metal according to the present invention, and L according to the invention
The lithium ion secondary batteries manufactured in the product battery container using the mixture sheet of the negative electrode active material precursor synthesized from the metal oxide supporting the i metal are all prepared from the lithium manganese oxide prepared by the conventional method. It can be seen that the discharge capacity is superior to the lithium ion secondary battery using the positive electrode active material. Further, according to the present invention, it can be seen that a lithium-ion secondary battery having particularly excellent discharge capacity and / or discharge voltage can be obtained.

[0073]

According to the present invention, a lithium ion secondary battery having a large discharge capacity or discharge voltage can be easily obtained with high safety and at a low manufacturing cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cylinder type lithium ion secondary battery manufactured in an example.

[Explanation of symbols]

 8 Positive Electrode Sheet 9 Negative Electrode Sheet 10 Separator 11 Battery Can 12 Battery Lid 13 Electrolyte 14 Safety Valve

Claims (22)

[Claims] 1. A lithium ion secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte, and a container in which they are hermetically accommodated, wherein the positive electrode is electrochemically charged with lithium ions in the container. Is inserted, the positive electrode active material precursor containing a lithium manganese oxide having a high lithium ion content as a main component, the lithium ion is electrochemically released from the positive electrode active material precursor, and the negative electrode, A lithium-ion secondary battery comprising a negative electrode active material formed by inserting lithium ions released from the positive electrode active material precursor into a negative electrode active material precursor containing a metal oxide as a main component. . 2. The positive electrode active material precursor is Li _{1 + x} Mn ₂ O ₄
A material having a tetragonal crystal structure represented by the composition formula (0.3 <x <1), wherein the positive electrode active material is Li _y Mn.
The lithium ion secondary battery according to claim 1, which is a substance having a cubic crystal structure represented by a composition formula of ₂ O ₄ (where 0 <y <0.3). 3. The positive electrode comprises Li _x CoO ₂ as a _secondary active material.
(0.5 <x ≦ 1) or Li _x Co _y Ni _z O ₂
The lithium ion secondary battery according to claim 1, comprising at least one of (0.5 <x ≦ 1, 0 ≦ y ≦ 1, 0 <z ≦ 1). 4. The positive electrode active material precursor according to claim 1, which is formed by an electrochemical self-discharge in the container between a lithium manganese oxide and metallic lithium or a lithium-containing alloy. Lithium-ion secondary battery. 5. A positive electrode active material precursor utilizes an external electrical circuit within the vessel between lithium manganese oxide and metallic lithium or a lithium-containing alloy carried in close proximity to the negative electrode active material precursor. The lithium ion secondary battery according to claim 1, which is formed by an electrochemical discharge. 6. The lithium-ion secondary battery according to claim 1, wherein the negative electrode active material is an amorphous mixed metal oxide containing tin as a main component, in which lithium ions are inserted. 7. The negative electrode active material precursor is an amorphous composite metal oxide containing tin as a main component, and its composition formula is SnL.
_k O _z (L is Al, B, P, Si, Periodic Table Nos. 1 to 3
Represents at least one atom selected from the group consisting of atoms of elements belonging to Group 3 and halogen atoms; and k and z
Represent numerical values satisfying 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6) or Sn _d Q _1-d L _k O _z (Q
Represents a transition metal atom; L represents Al, B, P, Si,
Represents at least one atom selected from the group consisting of atoms of elements belonging to Groups 1 to 3 of the Periodic Table and halogen atoms;
Then, d, k and z are respectively 0.1 ≦ d ≦ 0.9,
It represents a numerical value that satisfies 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6. ) The lithium-ion secondary battery according to claim 1, which is represented by 8. The ratio of the amount of lithium released during battery discharge to the amount of lithium inserted into the negative electrode active material precursor is determined by battery voltage 3
In the discharge up to V, x in the composition formula of the positive electrode active material precursor
The lithium ion secondary battery according to claim 2, which is represented by 1 / (1 + x) or less by using. 9. A lithium ion secondary battery precursor comprising a positive electrode precursor, a negative electrode precursor, a non-aqueous electrolyte, and a container that contains them in a sealed state, wherein the positive electrode precursor is in the container. In electrochemically, lithium ions are electrochemically inserted, and the positive electrode active material precursor mainly contains lithium manganese oxide having an increased lithium ion content, and the negative electrode precursor contains a metal oxide. A lithium ion secondary battery precursor comprising a negative electrode active material precursor as a main component. 10. The positive electrode active material precursor is Li _{1 + x} Mn ₂
The lithium ion secondary battery precursor according to claim 9, which is a substance having a tetragonal crystal structure represented by a composition formula of O ₄ (0.3 <x <1). 11. The positive electrode precursor comprises Li as a side active material.
_x CoO ₂ (0.5 <x ≦ 1) or Li _x Co _y Ni
The lithium ion secondary battery precursor according to claim 9, comprising at least one of _z O ₂ (0.5 <x ≦ 1, 0 ≦ y ≦ 1, 0 <z ≦ 1). 12. The positive electrode active material precursor according to claim 9, which is formed by an electrochemical self-discharge in the container between a lithium manganese oxide and metallic lithium or a lithium-containing alloy. Lithium-ion secondary battery precursor. 13. A positive electrode active material precursor utilizes an external electrical circuit in the container between lithium manganese oxide and metallic lithium or a lithium-containing alloy carried in proximity to the negative electrode active material precursor. 10. The lithium ion secondary battery precursor according to claim 9, which is formed by the electrochemical discharge. 14. The lithium ion secondary battery precursor according to claim 9, wherein the negative electrode active material precursor is an amorphous mixed metal oxide containing tin as a main component. 15. The negative electrode active material precursor is an amorphous mixed metal oxide containing tin as a main component, and the composition formula thereof is Sn.
L _k O _z (L is Al, B, P, Si, 1 to 1 of the periodic table
Represents at least one atom selected from the group consisting of atoms of elements belonging to Group 3 and halogen atoms; and k and z
Represent numerical values satisfying 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6) or Sn _d Q _1-d L _k O _z (Q
Represents a transition metal atom; L represents Al, B, P, Si,
Represents at least one atom selected from the group consisting of atoms of elements belonging to Groups 1 to 3 of the Periodic Table and halogen atoms;
Then, d, k and z are respectively 0.1 ≦ d ≦ 0.9,
It represents a numerical value that satisfies 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6. ] The lithium ion secondary battery precursor according to claim 9, which is represented by 16. A lithium ion secondary battery precursor comprising a positive electrode precursor raw material, a negative electrode precursor and a non-aqueous electrolyte, and a container accommodating them in a sealed state, wherein the positive electrode precursor raw material is lithium manganese. An oxide is contained as a main component, and the positive electrode active material precursor raw material is brought into contact with the lithium metal or lithium alloy in a state of being electrically short-circuited, and the negative electrode precursor contains a metal oxide as a main component. A lithium-ion secondary battery precursor, comprising: a negative electrode active material precursor. 17. The positive electrode active material precursor raw material is Li _{1 + x} M
The lithium ion secondary battery precursor according to claim 16, which is a substance having a tetragonal crystal structure represented by a composition formula of n ₂ O ₄ (0.3 <x <1). 18. The positive electrode precursor raw material is L as a side active material.
i _x CoO ₂ (0.5 <x ≦ 1) or Li _x Co _y N
i _z O ₂ (0.5 <x ≦ 1, 0 ≦ x ≦ 1, 0 ≦ z ≦ 1)
The lithium ion secondary battery precursor according to claim 16, comprising at least one of the above. 19. The lithium ion secondary battery precursor according to claim 16, wherein the positive electrode active material precursor raw material is a lithium manganese oxide having a spinel type crystal structure. 20. A lithium ion secondary battery precursor comprising a positive electrode precursor raw material, a negative electrode precursor and a non-aqueous electrolyte, and a container accommodating them in a sealed state, wherein the positive electrode precursor raw material is lithium manganese. An oxide as a main component, and the negative electrode precursor is one containing a negative electrode active material precursor having a metal oxide as a main component, and metallic lithium or a lithium alloy is electrically adjacent to the precursor. A lithium-ion secondary battery precursor, which is joined in a connectable state. 21. The lithium ion secondary battery precursor according to claim 20, wherein the negative electrode active material precursor is an amorphous mixed metal oxide containing tin as a main component. 22. The negative electrode active material precursor is an amorphous composite metal oxide containing tin as a main component, and the composition formula thereof is Sn.
L _k O _z (L is Al, B, P, Si, 1 to 1 of the periodic table
Represents at least one atom selected from the group consisting of atoms of elements belonging to Group 3 and halogen atoms; and k and z
Represent numerical values satisfying 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6) or Sn _d Q _1-d L _k O _z (Q
Represents a transition metal atom; L represents Al, B, P, Si,
Represents at least one atom selected from the group consisting of atoms of elements belonging to Groups 1 to 3 of the Periodic Table and halogen atoms;
Then, d, k and z are respectively 0.1 ≦ d ≦ 0.9,
It represents a numerical value that satisfies 0.2 ≦ k ≦ 2 and 1 ≦ z ≦ 6. 21. The lithium ion secondary battery precursor according to claim 20, which is represented by