JPH0644971A - Non-aqueous electrolyte lithium secondary battery - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a high energy density non-aqueous electrolyte lithium secondary battery, and an object thereof is to achieve high capacity while being manufactured under simple conditions. [Structure] The active material of the positive electrode 4, which faces the negative electrode 2 via the separator 5, is sparingly soluble in at least one kind of water selected from nickel oxide, oxyhydroxide, hydroxide and carbonate. Insoluble nickel compound powder, equimolar lithium halide, nitrate, sulfate, phosphate,
An aqueous solution of at least one water-soluble lithium salt selected from borate, acetate, and oxalate is added and thoroughly kneaded with stirring.
A composite oxide of lithium and nickel obtained by firing at 00 to 800 ° C. is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a relatively inexpensive composite oxide of lithium and nickel, which is expected as a high energy density storage battery for portable devices, electric vehicles, etc. because of its high voltage and high capacity. TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte lithium secondary battery using a material as a positive electrode active material.

[0002]

2. Description of the Related Art In order to achieve miniaturization and weight reduction of various portable devices and high performance such as mileage per charge of electric vehicles, research and development of high energy density storage batteries have been actively pursued all over the world. ing. In recent years, as a part of this, metals such as lithium or aluminum, wood alloys such as some types of aluminum alloys, lead, tin, bismuth, and cadmium, which are easily alloyed with lithium at room temperature, An active material holder capable of reversibly occluding and releasing lithium reversibly by charging and discharging, such as a carbon material such as graphite, an oxide, a sulfide, and a conductive polymer such as polyacetylene and polyaniline. Research and development and practical application of non-aqueous electrolyte lithium secondary batteries using a negative electrode mainly composed of are active.

MnO is used as the positive electrode active material.₂，
TiS₂, MoS₂, V₂O_Five, Cr₂O _Five, Nb₂O_Five, Li
CoO₂, LiNiO₂, LiFeO₂, LiMnO₂, L
iMn₂O_FourOxides of transition metals, such as chalcogen compounds
It is well known that materials, complex oxides with lithium, and the like.
These are layered or tunnel-shaped connections like intercalation compounds.
It has a crystal structure, and lithium ions are reversible due to charge and discharge.
It is possible to repeatedly release and occlude. In particular, Li
CoO₂And LiNiO₂And LiMn₂O_Four4V class high
Voltage positive electrode active material of non-aqueous electrolyte lithium secondary battery
Attention has been paid to the fact that among these, LiCoO₂Table
The composite oxide of lithium and cobalt is
Is also excellent. However, if cobalt is relatively expensive
Not only in Japan, but because the production areas are unevenly distributed in specific areas,
Concerns about supply uncertainties and rising prices due to changes in the situation are a problem
Has been done.

On the other hand, in the case of a composite oxide of lithium and manganese or nickel represented by LiMn ₂ O ₄ or LiNiO ₂ , the raw material compound of manganese or nickel is relatively inexpensive and stable supply is possible. There is no concern about cobalt, but in terms of characteristics, especially discharge capacity, LiC
It had the disadvantage that it was inferior to oO ₂ . Therefore, modification is being attempted by examining the synthesis and treatment conditions of these composite oxides. In particular, LiNiO ₂ is LiCo
Although the voltage is lower than O ₂ by about 0.2 V, it has a structure similar to that of LiCoO _2, and is therefore expected and attracting attention as a positive electrode active material for a high-capacity lithium secondary battery.

As a method for synthesizing a composite oxide of lithium and nickel represented by LiNiO ₂ , the conventional method of the Journal of American Chemical Society (J. Amer) has been used.
icanChemical Soc.) 76, 1499 (195)
As described in 4), it is synthesized by heating anhydrous lithium hydroxide and metallic nickel in an oxygen atmosphere to react with each other. However, as a positive electrode active material of a lithium secondary battery, the discharge capacity is small, I was not satisfied.

In addition, Chemistry Express (Ch
emistry Express) Volume 6, Issue 3, page 161 (199
In 1), equimolar 4.5 mol / 1 LiOH aqueous solution and 1.0 mol / 1 Ni (NO ₃ ) ₂ aqueous solution were mixed while maintaining at 60 ° C., stirred at the same liquid temperature for a long time, and dried under reduced pressure. A solidified precursor is obtained. Then, the powder obtained by crushing this precursor material is pre-baked at 300 ° C., and then 800 ° C.
It is described that a black composite oxide powder of lithium and nickel can be obtained by the main calcination. It has been reported that this composite oxide can serve as a positive electrode active material for a lithium secondary battery having a relatively high capacity.

[0007]

However, the composite oxide of lithium and nickel produced by the conventional synthesis method described above is
Those manufactured by a simple synthesis method are not suitable for the production of a non-aqueous electrolyte lithium secondary battery even if they have a small capacity without sufficiently functioning as a positive electrode active material or have a relatively high capacity as a battery material. Regardless of the laboratory, the condition management is very delicate and industrially complicated, and it takes a long time, poor reproducibility, and large variations in charge and discharge characteristics. there were.

According to the present invention, the composite oxide of lithium and nickel, which can be produced under relatively simple conditions, is used as the positive electrode active material. An object of the present invention is to provide a high-capacity non-aqueous electrolyte lithium secondary battery comparable to a battery using a composite oxide of lithium and cobalt, which was unstable in supply, as a positive electrode active material.

[0009]

In order to achieve the above-mentioned object, the present invention provides at least one of nickel oxide, oxyhydroxide, hydroxide and carbonate.
Seed water hardly soluble or insoluble nickel compound powder,
Chloride of lithium, iodide and other halides, nitrates, sulfates, phosphates, which are equimolar to the nickel compound,
An aqueous solution of at least one water-soluble lithium salt selected from borate, acetate, and oxalate is added and thoroughly kneaded with stirring.
A high-capacity non-aqueous electrolyte lithium secondary battery is realized by using a positive electrode mainly composed of a composite oxide of lithium and nickel obtained by firing in a temperature range of 00 to 800 ° C.

[0010]

By constructing a non-aqueous electrolyte lithium secondary battery using a positive electrode mainly composed of a composite oxide of lithium and nickel obtained by such means, it is relatively inexpensive and there is no fear of supplying raw materials. In addition, a compact, lightweight, high energy density storage battery with high capacity and high voltage can be achieved.

[0011]

EXAMPLES The details of the present invention will be described below with reference to examples.

(Example 1) 1 mol of each well-dried powdery nickel oxide NiO, nickel oxyhydroxide NiOOH, nickel hydroxide Ni (OH) ₂ and nickel carbonate NiCO ₃ was weighed and chlorinated. Lithium LiC
1, lithium iodide LiI, lithium nitrate LiNO ₃ ,
Lithium sulfate Li ₂ SO ₄ , Lithium phosphate Li ₃ PO ₄ ,
Lithium borate Li ₂ B ₄ O ₇ , Lithium acetate LiC ₂ H ₃
1 mol of a saturated aqueous solution of O ₂ and lithium oxalate Li ₂ C ₂ O ₄ at 20 ° C. was added little by little while stirring and kneading,
Then, continue stirring for about 5 hours. Then, it is dried at 80 to 100 ° C. while continuing the stirring and kneading.
If the process is performed under reduced pressure, it can be completed in a short time. After each of the produced cake-like solid substances was lightly crushed, a black baked powder which was heated at 750 ° for 12 hours in the atmosphere was obtained. If a rotary kiln type firing furnace is used for firing, continuous firing is possible, high productivity is achieved, and exhaust treatment is facilitated. The obtained black fired powder was identified by X-ray diffraction to be a composite oxide of lithium and nickel represented by LiNiO ₂ .

The charge and discharge characteristics of each of the composite oxides of lithium and nickel described above are shown in R2320 size (external diameter 2
A coin-shaped battery having a size of 3.0 mm and a height of 2.0 mm) was prototyped and confirmed. The structure of the prototype battery is shown in FIG. In FIG.
1 is a lid that also serves as a negative electrode terminal, 2 is a negative electrode made of lithium foil having a capacity of at least three times the capacity of the positive electrode pressed onto the lid 1,
3 is a case which also serves as a positive electrode terminal, 4 is a mixture of 0.15 in which the composite oxide as a positive electrode active material, acetylene black as a conductive agent, and fluororesin as a binder are mixed in a weight ratio of 7: 2: 1.
g was molded into a disk having a diameter of 17.5 mm at a pressure of ² t / cm ² and dried sufficiently, 5 was a microporous polypropylene film separator, 6 was a polypropylene gasket,
As the non-aqueous electrolyte, a 1 mol / 1 solution of lithium perchlorate in propylene carbonate was used. A battery B made of a composite oxide of lithium and nickel according to the above-mentioned literature as a conventional example of the same size and a battery C made of a complex oxide LiCoO ₂ of lithium and cobalt as a reference example were similarly manufactured. It was used as a comparative sample. The capacity of each cell is regulated by the positive electrode, and the charge / discharge test is 0.5 m at 20 ° C.
A constant current was charged to 4.3 V, and discharge was stopped at 3.0 V. The prototype battery under each condition was 10 cells, and the performance of each cell was the specific capacity of the positive electrode active material (mAh
/ G) was compared. Battery B has a specific capacity of 8
8 mAh / g, Battery C was 129 mAh / g, and the values for each positive electrode active material according to the present invention are shown in (Table 1).

[0014]

[Table 1]

Further, the discharge of the battery A used as the positive electrode active material according to the present invention starting from the nickel carbonate powder and the lithium oxalate aqueous solution shown in Table 1 and the battery B of the conventional example and the battery C of the reference example. A comparison of characteristic curves is shown in FIG. Each of the batteries using the positive electrode active material according to the present invention has a larger specific capacity than the battery B according to the conventional example and has a discharge voltage of about 0.2.
Although it is lower than the battery C of the V reference example, there are many large specific capacity that is almost the same level. In other words, the battery according to the present invention has the same discharge voltage as that of the conventional example, but has a large specific capacity, and when the composite oxide of lithium and cobalt, which has the highest capacity in the past, is used as the positive electrode active material. A high-capacity battery comparable to the above can be realized.

(Example 2) In Example 1, the case where the firing temperature was 750 ° C. was shown, but an appropriate firing temperature range was examined.

To the dried nickel hydroxide Ni (OH) ₂ powder, a saturated aqueous solution of equimolar lithium acetate LiC ₂ H ₃ O ₂ at 20 ° C. was added while kneading and stirring to give a mixture of 80-
Dry at 100 ° C. to obtain a cake-like solid. This solid is heated to 550 to 900 ° C by changing the temperature by 50 ° C.
A coin-type battery was trial-produced in the same manner as in Example 1 using the sample fired for a period of time as a positive electrode active material. The specific capacity obtained by the charge / discharge test under the same conditions as in Example 1 is shown in FIG. From the result of FIG. 3, it can be understood that the firing temperature is appropriately in the range of 600 to 800 ° C. In Example 2, nickel hydroxide was used as the nickel source and lithium acetate was used as the lithium source. However, the temperature range of 600 to 800 ° C. is appropriate over all combinations of the nickel source and the lithium source of the present invention. Have confirmed that.

(Example 3) Using the positive electrode active materials of the batteries A, B and C shown in FIG. 2 of Example 1, an AA type (R6) battery shown in FIG. 4 was manufactured. In FIG. 4, 1
Reference numeral 1 is a positive electrode plate, which was formed on both sides of the core material of the aluminum foil, and
A positive electrode mixture paste having the same composition as the above was applied, dried, and then pressed with a roller to prepare. The fluororesin used as the binder was a dispersion type. 12 is a negative electrode plate,
A black powder, which is a lithium active material holder, and a polyvinyl chloride (cyclohexanone solution), which is a binder, are applied on both sides of a copper foil as a core material in a weight ratio of 9: 1, dried, and pressed to prepare. . Each of the positive electrode plate 11 and the negative electrode plate 12 is wound in a tight spiral through a separator 13 made of a microporous polypropylene film to form an electrode plate group. Positive plate 1
A positive electrode lead 11a and a negative electrode lead 12a made of the same material as the core material are attached to the 1 and the negative electrode plate 12, respectively. The insulation plates 14 and 15 made of polyethylene are arranged above and below the electrode plate group and housed in a case 16, and the negative electrode lead 12a is electrically connected to the inner bottom surface of the case 16 which also serves as a negative electrode terminal. Reference numeral 17 denotes a lid, and the lid 17 is a polypropylene lid main body 17a, a lower washer 17c and an upper washer 17d made of aluminum is caulked and sealed with a rivet 17e, and a nickel plated steel cap 17b and an upper washer 17d are welded together. It was created. After the positive electrode lead 11a was electrically connected to the lower washer 17c of the lid, a non-aqueous electrolyte was injected in an amount enough to hold the electrode plate group, and then the upper edge of the case 16 was curved and sealed. The non-aqueous electrolyte having the same composition as in Example 1 was used.

Prototype battery R6A using a composite oxide of lithium and nickel according to the present invention prepared by using nickel carbonate as a nickel source and lithium oxalate as a lithium source as a positive electrode active material, the same conventional example as in Example 1. FIG. 5 shows an average discharge characteristic curve of each of 10 cells in the 5th cycle, where R6B and R6C are prototype batteries using the positive electrode active material of Reference Example.
Shown in. It can be understood that R6A according to the present invention has a larger capacity than the conventional example R6B and has a lower voltage than the reference example R6C by about 0.2 V, but the same capacity. Although only one example of the discharge characteristic of the positive electrode active material according to the present invention is shown, a battery made of the positive electrode active material obtained by the combination of each plain or mixed nickel source and each plain or mixed lithium source according to the present invention is All of them have higher capacities than the conventional examples, and the performance is comparable to that of the battery using the composite oxide of lithium and cobalt which is the most excellent positive electrode active material at present.

In Examples 1, 2 and 3, the case where lithium or graphite was used for the negative electrode was exemplified. However, a metal that is easily alloyed with lithium, certain oxides, sulfides, conductive polymers, etc. Occludes lithium,
A high-capacity lithium secondary battery can be formed also when an active material holder capable of repeating discharge is used for the negative electrode. Further, although the organic solvent solution of a lithium salt has been described as the non-aqueous electrolyte, the present invention is not limited to this, and a solid electrolyte made of polyethylene oxide in which lithium iodide or a certain lithium salt is dispersed. It is also applicable to.

[0021]

As described above, the present invention is based on nickel oxide,
At least one kind of water-insoluble or insoluble nickel compound powder selected from nickel oxyhydroxide, nickel hydroxide, and nickel carbonate is added to a lithium halide such as lithium chloride or lithium iodide in an equimolar amount to the nickel compound. , Lithium nitrate, lithium sulphate, lithium phosphate, lithium borate, lithium acetate, lithium oxalate. At least one water-soluble lithium salt aqueous solution is added, and the mixture is thoroughly stirred and kneaded, then dried and solidified. By using a positive electrode mainly composed of a composite oxide of lithium and nickel, which is produced by a simple method of firing the cake-like substance at a temperature of 600 to 800 ° C. A non-aqueous electrolyte lithium containing a complex oxide of lithium and nickel as a positive electrode active material, which was difficult to increase in capacity The problem of beam rechargeable battery, presently, are those capable of improving the capacity of the composite oxide of lithium and cobalt is most high capacity to a level comparable to a battery to a positive electrode active material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a coin type non-aqueous electrolyte lithium secondary battery according to an embodiment of the present invention.

FIG. 2 is a discharge characteristic curve diagram of a coin-type battery according to the present invention compared with a conventional example and a reference example.

FIG. 3 is a diagram showing the relationship between the firing temperature and the specific capacity of a prototype battery during the production of the positive electrode active material according to the present invention.

FIG. 4 is a sectional view of a cylindrical non-aqueous electrolyte lithium secondary battery according to another embodiment of the present invention.

FIG. 5 is a discharge characteristic curve diagram of the cylindrical battery according to the present invention in comparison with the conventional example and the reference example.

[Explanation of symbols]

 1 Lid 2 Negative electrode 3 Case 4 Positive electrode 5 Separator 6 Gasket

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. Nickel oxide, nickel oxyhydroxide,
At least one kind of water-insoluble or insoluble nickel compound powder selected from nickel hydroxide and nickel carbonate, and lithium halide such as lithium chloride or lithium iodide having the same molar amount as the above nickel compound, lithium nitrate, sulfuric acid Lithium, lithium phosphate, lithium borate,
After adding an aqueous solution of at least one water-soluble lithium salt selected from lithium acetate and lithium oxalate and thoroughly kneading with stirring, the cake substance dried and solidified is heated in the temperature range of 600 to 800 ° C. A non-aqueous electrolyte lithium secondary battery using a positive electrode mainly composed of a composite oxide of lithium and nickel obtained by firing. 2. Nickel oxide, nickel oxyhydroxide,
Lithium halide such as lithium chloride or lithium iodide in an equimolar amount to the nickel compound, which is added to at least one kind of water-insoluble or insoluble nickel compound powder selected from nickel hydroxide and nickel carbonate,
The aqueous solution of at least one water-soluble lithium salt selected from lithium nitrate, lithium sulfate, lithium phosphate, lithium borate, lithium acetate and lithium oxalate is saturated or at a concentration close to saturation at room temperature. Non-aqueous electrolyte lithium secondary battery. 3. Nickel oxide, nickel oxyhydroxide,
At least one kind of water selected from nickel hydroxide and nickel carbonate is added to a powder of a poorly soluble or insoluble nickel compound, and lithium chloride in an equimolar amount to the nickel compound,
Lithium halides such as lithium iodide, lithium nitrate, lithium sulfate, lithium phosphate, lithium borate,
At least one aqueous solution selected from lithium acetate and lithium oxalate An aqueous solution of a lithium salt is added and sufficiently kneaded, and then dried in air or under reduced pressure while evaporating and drying. The non-aqueous electrolyte lithium secondary battery according to claim 1, which is solidified. 4. The method according to claim 1, wherein metallic lithium is used as the negative electrode.
Alternatively, the non-aqueous electrolyte lithium secondary battery described in 3. 5. An active material holder, which is capable of repeatedly absorbing and desorbing lithium by charge and discharge of a metal which is easily alloyed with lithium, a certain kind of carbon material, oxide, sulfide, conductive polymer or the like. The non-aqueous electrolyte lithium secondary battery according to claim 1, wherein the negative electrode is used.