JPS62140357A - Nonaqueous electrolyte secondary cell - Google Patents

Abstract

PURPOSE:To suppress the action of a fusible alloy against the electrolyte, and obtain a stable charge and discharge cycle, by forming a metallic layer not participating in the charge and discharge reactions at the surface of the fusible alloy negative electrode facing the opposite electrode. CONSTITUTION:At the negative electrode of a nonaqueous electrolyte secondary cell, a fusible alloy 2 of Pb-Bi-Cd type is applied, and at its surface facing the opposite electrode, a Ni layer 1 not participating in the charge and discharge reactions is vacuum evaporated. The negative electrode 2 formed with such a layer 1 can control the action of the alloy 2 against the electrolyte and obtain a stable charge and discharge cycle without losing the primary property as a negative electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a non-aqueous electrolyte secondary battery, and particularly relates to an improvement of its negative electrode coating material. It is known that lithium, sodium, aluminum, etc. are used as negative electrode active materials in non-aqueous electrolyte secondary batteries. Furthermore, in order to prevent dendrites from forming in such a negative electrode active material, it is known to use an alloy such as a fusible metal for the negative electrode material.

Such alloys include alloys of low melting point metals such as Cd, Pb, Bi, and Sn, and high melting point metals such as 5n-Ni.
There are alloys, etc. Among fusible alloys, Pb-In-Cd alloys and Pb-Bi have the highest storage capacity for negative electrode active materials.
-cd gold alloy, with a storage capacity of about 1700 mAh/cc.

The characteristics of fusible metals are listed below.

(1) The charging and discharging levels can be controlled and designed by selecting the alloy system.

(2) Generally has good ductility and excellent workability.

((b) Since low melting point metals (CD, Bi, Sn, Pb, etc.) are used, the energy consumption associated with alloying is lower than that of high melting point 5n-Ni alloys, etc., and manufacturing is possible at low cost.

3 Page-5 In addition to the above, there are Ll-A1 alloys and Li-Hg alloys that use lithium as an active material, but compared to fusible alloys, Li-A4 alloys generally have a β phase (lithium in atomic ratio). (45-55%) is not available, so the capacity is small. A small Li-Hg alloy becomes liquid during discharge, making it difficult to form an electrode plate.

Problems to be Solved by the Invention In such a conventional configuration, the Li f active material is used, and the electrolyte contains lithium perchlorate (hereinafter abbreviated as LiC, 504), oglopyrene carbonate (hereinafter abbreviated as PC), and dimethoxy. When a solution dissolved in a mixed solution of ethane (hereinafter abbreviated as DME) is used, the electrolyte decomposes on the surface of the active negative electrode alloy after about a hundred cycles, making charging and discharging impossible.

The present invention aims to solve these problems.

JQ about the problems! In order to solve the above-mentioned problems, the present invention uses a fusible alloy as the negative electrode material of a non-aqueous electrolyte secondary battery, and a metal layer that does not participate in the charge/discharge reaction is provided on the surface of the opposite electrode. It was formed.

Function: The fusible metal negative electrode formed with the metal layer in the present invention is the original fusible metal negative electrode! 1! It becomes possible to obtain a stable charge-discharge cycle by suppressing the action of the fusible metal on the electrolytic solution to a minimum of ψ;11; without losing i-characteristics. The thickness of the metal layer here is preferably 0.05 to 10 μm, and the metal element is preferably a transition metal element in the fourth period of the periodic rule.

In the present invention, examples of the case where lithium is used as a negative active material will be explained with reference to FIGS. 1 to 3.

The negative electrode used here was a pb-Bi with an outer diameter of 15πM and a thickness of 1007+m, with an N1 layer of 1m thick formed on the opposite electrode side.
-Ccl-based fusible alloy (Pb:Bi:Cd=40:40
:20 weight papart 1.). N1 layer d: Formed by electron beam heating vapor deposition. In this case, Ni was selected for the metal layer, but single-pole tests showed that elements within the scope of the present invention, that is, transition elements in the fourth period of the periodic law, have a performance of approximately the same as N1. Ta. Further, when the thickness of the metal layer was less than 0.05 μm, the metal layer was not uniformly deposited on the alloy surface, and the active alloy surface was exposed, causing decomposition of the electrolyte. It was also found that when the thickness is 10 μm or more, it is difficult for the negative electrode fusible alloy to occlude the negative electrode active material. Therefore, a suitable metal layer thickness is between 0.05 and 10 μm.

FIG. 1 shows a partial cross-sectional view of a battery with an outer diameter of 20 and a total height of 1.6 mm used to carry out the present invention.

In the figure, reference numeral 1 indicates a metal layer of the present invention, in which Ni is used here.

Reference numeral 2 is a negative electrode alloy made of a P b -B i -Cd based fusible alloy according to the present invention, and is crimped and fixed to a stainless steel negative electrode current collector 3 formed on the inner surface of a stainless steel sealing plate 4 . 5
is a stainless steel case, 6 is a titanium positive electrode current collector, 7 is a positive electrode mixture using molybdenum trioxide as a positive electrode active material, 8 is a separator made of polypropylene (hereinafter abbreviated as PP) with micropores, and 9 is impregnated with PP. 10 is a gasket made of PP.

The composition of the positive electrode was MOo (100 parts by weight), 15 parts of anti-vibration carbon black, and 6 parts of a fluororesin binder.

15 parts were mixed, filled and punched to have a capacity of 80 mAh.

The electrolyte is PC in which 1 mol/4 Lie eo 4 is dissolved.
A mixed solution containing DME and DME at a volume ratio of 1:1 was used.

The negative electrode was prepared by depositing a N1 layer 1 on a P b -B i -Cd based fusible alloy 2 by the method described above. Although not shown in Figure 1, lithium as the negative electrode active material was punched out to have a capacity of 50 mAh and pressure-bonded to the surface of the N1 layer 1. It is occluded in the negative electrode alloy 2 due to diffusion due to the gradient.

FIG. 2 shows the charge/discharge curve of the battery of the present invention at the 40th cycle. The charging and current currents were both 1 mA, the cut voltage during charging was 3 V, and the cut voltage during discharging was 1 V.

In the figure, A is the one using the negative electrode of the present invention, and B is the one using the Pb-B1-Cd alloy which has not been subjected to the treatment of the present invention. As shown in Figure 2, the negative electrode of the present invention is used.
It can be seen that there is no difference in charge/discharge curves compared to those not subjected to the treatment of the present invention.

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FIG. 3 shows the cycle characteristics of the battery shown in FIG. 1. In the figure, a person uses the negative electrode of the present invention, B
The present invention is T11! It has not been subjected to

FIG. 3 shows that the battery using the negative electrode of the present invention has excellent cycle characteristics.

As is clear from the explanation in ``Effects of the Invention'' (2), the non-aqueous electrolyte secondary battery using the negative electrode of the present invention has no difference in polarization during charging and discharging compared to conventional batteries, and has stable charge-discharge cycle characteristics. It is something that you have.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a battery in an embodiment of the present invention;
FIG. 2 is a diagram showing the charge-discharge curve of the same battery, and FIG. 3 is a diagram showing the cycle characteristics of the same battery. 1... Metal layer, 2... Negative electrode alloy, 3... Negative electrode current collector, 4... Sealing plate. Name of agent: Patent attorney Toshio Nakao and one other person (A
) Tama 3 Station Kuzu

Claims (3)

[Claims] (1) A battery comprising a nonaqueous electrolyte with an alkali metal salt as a supporting electrolyte, a rechargeable positive electrode, and a negative electrode made of a fusible metal material, wherein the negative electrode made of the fusible metal material is on the opposite electrode side. A non-aqueous electrolyte secondary battery that has a metal layer that does not participate in charging and discharging reactions. (2) The non-aqueous electrolyte secondary battery according to claim 1, wherein the metal layer comprises one or more of the transition metal elements in the fourth period of the periodic law. (3) The nonaqueous electrolyte secondary battery according to claim 1, wherein the metal layer has a thickness of 0.05 to 10 μm.