JPH01128355A - Nonaqueous solvent cell - Google Patents

Abstract

PURPOSE:To improve the cell capacity, the charge and discharge cycle life, and the like, by using a compound mainly of a noncrystalline vanadium pentoxide in which a specific amount of crystal-phase vanadium pentoxide is added as a positive electrode active substance. CONSTITUTION:In a compound mainly of a noncrystalline vanadium pentoxide, a crystalline phase compound of 1 to 50vol.% is added, and the resultant compound is used as the positive electrode active substance. As the said compound, a compound shown as the general formula (V2O5)100-xMx [where M is B2O3, P2O5, SiO2, Bi2O3, TeO2, WO3, MoO2, NbO2, GeO2, Ag2O, CuO, PbO, Sb2O3, SnO2, or TiO2, and 0<=x<=30 (Mol ratio)] is used. As the positive electrode, a positive electrode in which a positive electrode active substance such as a noncrystalline vanadium pentoxide powder is, together with a conductive material and a crystallization material, formed into pellet form, a sheet form, or a coating membrane, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention No. 1 (Industrial Application Field) The present invention relates to a non-aqueous solvent battery, and particularly to a non-aqueous solvent battery with an improved positive electrode active material.

(Prior art) In recent years, nonaqueous solvent batteries that use light metals such as lithium, sodium, and aluminum as negative electrode active materials have attracted attention as high-energy density batteries, and manganese dioxide (Mn 02 ) and fluoride as positive electrode active materials have been attracting attention as high-energy density batteries. Primary batteries using carbon [(CF)n, thionyl chloride (SOC,!'2), etc. have already been used in calculators,
It is widely used as a power source for watches and as a backup battery for memory. Furthermore, in recent years, with the miniaturization and weight reduction of various electronic devices such as VTRs and communication devices, the demand for high energy density secondary batteries as their power sources has increased, and non-aqueous solvent-based batteries in which light metals are used as negative electrode active materials have increased. Research is being actively conducted.

Nonaqueous solvent secondary batteries use light metals such as lithium, sodium, and aluminum for the negative electrode, and propylene carbonate (PC) and 1,2-dimethoxyethane (DME) as the electrolyte.
, γ-butyrolactone (γ-BL), tetrahydrofuran (THF), and other non-aqueous solvents.
It is composed of dissolved electrolytes such as iBF4, LiAsF6, LIPF6, etc., and the positive electrode active materials are mainly crystalline TiS2, MoS2, V205.
, V6O13, and other compounds that undergo topochemical reactions with lithium have been studied.

However, as for the above-mentioned secondary batteries, only some small-capacity coin-shaped batteries are currently in practical use, and large-capacity batteries such as cylindrical batteries have not yet been put into practical use.

On the other hand, recently, vanadium pentoxide (V
Nonaqueous solvent batteries using 2O3) as a positive electrode active material are being considered. When amorphous vanadium pentoxide is combined with metallic lithium to make a battery, it is attracting attention because it is expected to have high voltage and energy density more than twice that of current nickel-based cadmium storage batteries. However, research on such batteries has just begun, and there have been problems with characteristics such as battery capacity and charge/discharge cycle life.

(Problems to be Solved by the Invention) The present invention has been made to solve the above conventional problems, and aims to provide a non-aqueous solvent battery with excellent characteristics such as battery capacity and charge/discharge cycle life. That is.

[Configuration of the Invention (Means for Solving Problems)] The present invention provides a positive electrode having a positive electrode active material made of a compound mainly composed of amorphous vanadium pentoxide, a negative electrode made of a light metal, and a negative electrode in a non-aqueous solvent. A non-aqueous solvent battery equipped with an electrolytic solution containing an electrolyte, characterized in that the compound mainly composed of amorphous vanadium pentoxide contains a crystalline phase of 1 to 50% by volume. It is a non-aqueous solvent battery.

The compound mainly composed of amorphous vanadium pentoxide has the general formula % [However, M in the formula is B 203 , P 205 , Si
02 , Bi 203 , Te o2, WO3, M O
O2, N b O2, G e O2, A g 20, C
U O,, P b O%S b 203 , S n O
2, Tl 02 and x is 0≦X≦30 (molar ratio), which can be used. When X in this formula is 0, the positive electrode active material is composed only of vanadium pentoxide, but from the viewpoint of improving cycle characteristics, it is effective to add an oxide represented by M in the formula, and in particular, B
2O3, P2O5, St 02 , Bi 203 , M
If o o2 and WO3 are added, a remarkable effect can be exhibited.

Note that if the amount of the oxide exceeds 30 mol%, the battery capacity will decrease.

A more preferable ratio of oxide (M) is 2 to 20 mol%.

The reason for limiting the volume ratio of the crystalline phase contained in the compound mainly composed of amorphous vanadium pentoxide is that if the crystalline phase is less than 1% by volume, high battery capacity and stable cycle characteristics cannot be achieved. On the other hand, if the crystal phase exceeds 50% by volume, charge/discharge characteristics deteriorate. The more preferable crystal phase content is 1 to
It is 30% by volume.

In order to make such amorphous vanadium pentoxide contain a crystalline phase, the steps are: (1) mixing amorphous vanadium pentoxide and crystalline vanadium pentoxide in a predetermined ratio, (2) heating amorphous vanadium pentoxide at an appropriate temperature ( For example, a method may be adopted in which heat treatment is performed at a temperature (below the crystallization temperature) or (2) heat treatment is performed at an appropriate cooling rate when producing amorphous vanadium pentoxide. In particular, in consideration of battery characteristics, the method (2) above is preferable. Note that amorphous vanadium pentoxide can be produced by a liquid quenching method, a sol-gel method, etc., but the method is not particularly limited. The liquid quenching method may be either a single roll method or a twin roll method, and when obtaining a powder sample using a liquid refrigerant as in the rotary liquid jetting method, it is preferable to use liquid nitrogen.

The positive electrode may be formed into a pellet shape by molding amorphous vanadium pentoxide compound powder, which is the main positive electrode active material, together with a conductive material and a binder, or amorphous vanadium pentoxide compound powder, which is a main positive electrode active material, and a conductive material and a binder. A sheet-like material that has been kneaded and formed into a sheet with a bonding material, or a coating film that is obtained by suspending amorphous vanadium pentoxide powder, a conductive material, and a binding material in an appropriate solvent and applying this onto a substrate. can be mentioned.

(Function) According to the present invention, by using a positive electrode whose positive electrode active material is a compound mainly composed of amorphous vanadium pentoxide containing 1 to 50% by volume of a crystalline phase, A non-aqueous solvent battery having high battery capacity and stable cycle characteristics can be obtained.

(Example of the invention) Examples of the present invention will be described in detail below.

Example 1 First, commercially available vanadium pentoxide (V2O3) powder and boron oxide (B2O3) powder were mixed at a molar ratio of 95:5, and after melting this mixture at about 800°C, it was rapidly cooled by a twin roll method. did. This sample was analyzed by X-ray diffraction and differential thermal analysis (
DSC analysis) revealed that 2 in X-ray diffraction.
One pro-do peak is seen near e -25', and D
Since the crystallization temperature was 240°C in SC analysis, it was confirmed that it was an amorphous substance. Subsequently, this sample was heat-treated at 180° C. for 10 hours to partially crystallize it. This sample was confirmed to have a crystalline phase at 12% by volume based on the calorific value ratio (relative to only the amorphous phase) in DSC analysis.

Then, the amorphous V2O containing 12% by volume of crystalline phase
5. B2O3 powder (positive electrode active material > 80% by weight, 15% by weight of acetylene black, and 5% by weight of polytetrafluoroethylene were mixed in a v mixer and formed into a pellet, which was used as the positive electrode, lithium alone as the negative electrode, and an electrolyte solution. A non-aqueous solvent battery was constructed using 2-methyltetrahydrofuran in which 1.5 mol/) of LI As F6 was dissolved. Note that the battery size was AA.

Comparative Example 1 A non-aqueous solvent battery was assembled in the same manner as in Example 1 except that amorphous V2O5/B2O3 powder was used as the positive electrode active material.

Comparative Example 2 Amorphous V containing 60% by volume of crystalline phase as positive electrode active material
A non-aqueous solvent battery was assembled in the same manner as in Example 1 except that 2O5.B2O3 powder was used.

For the non-aqueous solvent batteries of Example 1 and Comparative Example 1.2, the current density was 0.5 mA/d and the voltage range was 2.5 mA/d.
When the battery characteristics were investigated by charging and discharging between 0 V and 3.5 V, the characteristic diagram shown in FIG. 1 was obtained.

Note that A plotted in FIG. 1 is the characteristic of the battery of Example 1, B is the characteristic of the battery of Comparative Example 1, and C is the characteristic of the battery of Comparative Example 2. As is clear from FIG. 1, the non-aqueous solvent battery of Example 1 (plot A) has a capacity density of 200 Ah//(g or more based on the positive electrode active material) and stable cycle characteristics. In contrast, the non-aqueous solvent battery of Comparative Example 1 (plot B
) is almost constant at 170-180Ah//(g) based on the positive electrode active material, which is a reduction of about 2 compared to Example 1. In addition, in the non-aqueous solvent battery of Comparative Example 2 (plot C), the initial It can be seen that although the value is large, the cycle characteristics are low, and the energy density is halved after about 150 cycles.

Example 2 and Reference Example A mixture having the composition shown in Table 1 below was made amorphous using twin rolls, and then heat-treated to produce a mixture consisting mainly of six types of amorphous V2O5 containing approximately 15% by volume of crystalline phase. A compound was prepared. Subsequently, a non-aqueous solvent battery was assembled in the same manner as in Example 1 except that these V2O5-based compounds were used as the positive electrode active material.

Therefore, for the nonaqueous solvent batteries of Example 2 and Reference Example, the current density was 0.5 mA/ci, and the voltage range was 2.0 V to 3 V.
．． Charging and discharging between 5V and the second cycle capacity (
C2) and the ratio of the capacity density at the 60th cycle to the capacity density at the 2nd cycle (C6o/C2) were investigated. The results are also listed in Table 1.

Table 1 As is clear from Table 1 above, the non-aqueous solvent battery (hhl~5) of the present invention has a high capacity density in the second cycle and stable cycle characteristics. In contrast, it can be seen that the non-aqueous solvent battery of the reference example (Arashi 6) has a low capacity density.

Example 3 A mixture having the composition shown in Table 2 below was made amorphous using twin rolls, and then heat treated to form a mixture with a different content ratio of crystalline phases.
Three types of amorphous v205-based compounds were prepared.

Subsequently, a non-aqueous solvent battery was assembled in the same manner as in Example 1 except that these V2O5-based compounds were used as the positive electrode active material.

Therefore, for the nonaqueous solvent battery of Example 3, the current density was 0.5 mA/cd, and the voltage range was 2.0V to 3.5V.
Charge and discharge were performed in between, and the capacity at the second cycle (C2) and the ratio of the capacity density at the 60th cycle to the capacity density at the second cycle (C60/C2) were examined. The results are also listed in Table 2.

Table 2 As is clear from Table 2 above, the non-aqueous solvent battery of Example 3 has high capacity density and excellent cycle characteristics, similar to Example 1.2.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a non-aqueous solvent battery with excellent characteristics such as battery capacity and charge/discharge cycle life.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the cycle characteristics of capacity density in Example 1 and Comparative Examples 1.2. Applicant's agent Patent attorney Takehiko Suzue

Claims (3)

[Claims] (1) In a non-aqueous solvent battery equipped with a positive electrode whose active material is a compound mainly composed of amorphous vanadium pentoxide, a negative electrode made of a light metal, and an electrolyte solution in which an electrolyte is dissolved in a non-aqueous solvent. . A non-aqueous solvent battery, characterized in that the compound mainly composed of amorphous vanadium pentoxide contains a crystalline phase in a volume ratio of 1 to 50%. (2), a compound mainly composed of amorphous vanadium pentoxide has the general formula (V_2O_5)_1_0_0_-_xM_x [however,
M in the formula is B_2O_3, P_2O_5SiO_2, B
i_2O_3, TeO_2, WO_3, MoO_2, N
bO_2, GeO_2, Ag_2O, CuO, PbO,
Sb_2O_3, SnO_2, TiO_2, x is 0≦x
≦30 (molar ratio)] The non-aqueous solvent battery according to claim 1, wherein (3) The non-aqueous solvent battery according to claim 1, wherein the light metal used in the negative electrode is lithium alone or an alloy mainly composed of lithium.