JPH02253569A - Manufacture of solid state secondary battery - Google Patents

Abstract

PURPOSE:To increase adhesion between layers and to improve performance and life by arranging a thermoplastic resin porous member on one side of positive or negative electrode layer and on each side of an electrolyte layer, then by press-bonding them at a resin softening temperature or higher. CONSTITUTION:In a process in which an electrolyte layer is interposed between positive and negative electrode layers and they are bonded by heating, a thermoplastic resin porous member is arranged on each one side of positive and negative electrode layers, and on both sides of the electrolyte layer, then they are press-bonded at a resin-softening temperature or higher. Increase in internal resistance is decreased compared with where a large amount of binder is added to the electrode or the electrolyte, and decrease in adhesion between layers caused by expansion attendant on charge-discharge cycles is retarded. Capacity shortage in the early charge-discharge stage and short charge-discharge cycles are prevented, and the discharge capacity, self discharge, and cycle life of a solid state secondary battery are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a so-called solid state secondary battery whose constituent materials are all solid.

Conventional technology Among the batteries used as various power sources, so-called solid-state batteries, whose constituent materials are all solid, are used primarily for reasons such as leakage, high reliability, and the ability to be made smaller and lighter. Both secondary batteries have been attracting attention. Currently, it is mainly used for memory backup of various devices.

In this solid-state battery, the solid electrolyte is particularly important, and L
i L Li0 ion conductive solid electrolyte such as Li5H, Rb A g a Is, Agl-Ag2O, Ag
Ag4 ion conductive solid electrolyte such as I-Moon, H
″″Ionic conductive solid electrolyte, further RbCu4I +
, s Cl g, 6, Cu'' ion conductive solid electrolytes such as Cu l-Cu20-M2O3.

Mana, positive electrode materials include Cue, +T i S2, and A.
gs, +Ti5e, Cu@, +NbS*1 Aga, +
NbS*1Wow, and more Cu y M o s S
*-! , F ey M oe S * -z
Chevrel phase compounds such as

On the other hand, the negative electrode contains CulA glL i +, 5WOs,
Furthermore, Chevrel phase compounds similar to those for positive electrodes have been attempted.

As with other batteries, there are many methods for manufacturing these batteries, but one method that is industrially effective is to form a layer containing mainly an electrode active material and a binder on both sides, and a layer containing an electrolyte and a binder in the center. Examples include a step of disposing a main layer and integrating it by heating, providing an electrically conductive layer containing a binder on the outside thereof, and also integrating it by heating.

Problems to be Solved by the Invention As a manufacturing method for a solid-state battery, a layer mainly containing an electrode material and a binder is placed on both sides, and a layer mainly containing an electrolyte and a binder is arranged in the center.
The method of integrating by heating is an excellent manufacturing method that is simple and allows for continuous production, which cannot be used in batteries that use other general solutions as electrolytes.

However, if the amount of binder is increased too much to ensure sufficient adhesion between the electrode material layer and the electrolyte layer, the internal resistance will increase and the charge/discharge characteristics will deteriorate. However, if the amount is too small, not only will the adhesion be poor, but the charging and discharging characteristics will also deteriorate because it is impossible to suppress the slight expansion of the electrodes that occurs during the charging and discharging process. That is, in any case, there is still room for improvement in discharge characteristics, lifespan, self-discharge characteristics, etc.

The present invention aims to solve the problems of the prior art.

Means for Solving the Problems The present invention provides a manufacturing method in which layers mainly containing electrode materials and binders are arranged on both sides, and a layer mainly containing electrolyte and binder is placed in the center, and the layers are integrated by heating. In this method, a layer mainly containing positive and negative electrode materials and a binder is formed on a porous body made of thermoplastic resin, and the surface of this porous body is brought into contact with an electrolyte layer that integrates it, and the layer is heated to a temperature at which the porous body softens and melts or above. Pressurize and integrate at a temperature above.

Alternatively, a porous body made of thermoplastic resin may be placed on both sides of a layer mainly containing an electrolyte and a binder, and the two polar layers and this porous body may be integrated under pressure at a temperature at or above the temperature at which the porous body softens and melts. . Note that the porous body is not a special material, and may be a screen made of thermoplastic resin, a punched metal shape, or an expanded metal shape.

Function The present invention provides a manufacturing method in which electrode layers are placed on both sides and an electrolyte layer is placed in the center, and integrated by heating. A porous body made of thermoplastic resin is disposed in the crab, and both polar layers and the electrolyte layer are integrated under pressure at a temperature at which the porous body softens and melts or at a temperature higher than that. As a result, the porous material at the joint portion between the polar layer and the electrolyte layer melts, and a large amount of porous adhesive is present in this portion, improving the adhesion of the layers. Therefore, when a large amount of binder is added to the electrode or electrolyte, there is no increase in internal resistance.
Furthermore, it is possible to suppress the decrease in adhesion between the electrode and the electrolyte due to expansion during charging and discharging, thereby preventing initial capacity shortage and deterioration during a small number of charging and discharging cycles.

Example The present invention will be explained in detail below.

Copper Chevrell (Cu, Mo・S・) was used as the material for the positive electrode, and RbCuaI+, @C1a,
30wt% of S, 7wt% of polyethylene as a binder.
After adding the hot benzene solution and stirring thoroughly, a sheet with a wire diameter of 0.1 mm and a thickness of 0.35 mm is formed on a 30-mesh polyethylene screen using the known doctor blade method. .

On the other hand, the negative electrode also uses copper Chevrell (CuaMOaS*) and the electrolyte RbCuJI+, %C1s, like the positive electrode.

After thoroughly stirring 30 wt% of 6 using a binder under the same conditions, 0.35 m of 6 was placed on a polyethylene screen.
A sheet is formed to a thickness of m by a known doctor blade method.

In addition, Rb Cua I +, sCl s as electrolytes
, s, and the same binder to prepare a sheet with a thickness of 0.22 mm. No screen was used here.

Next, the positive and negative electrodes are stacked with the electrolyte layer at the center, with the screen side facing the electrolyte layer, and a commercially available carbon film with carbon black dispersed in rubber is applied to the outside as a current collector. 160℃, 500Kg/c
The electrodes were continuously pressurized and integrated using a roller press machine under conditions of 1.5 m''.The electrodes were cut into pieces with a size of 30 x 30 mm, and lead wires were attached to both the positive and negative electrodes, followed by room-temperature curing epoxy resin. A battery was constructed by coating with

This battery is called A.

Next, for comparison, a battery B was prepared in the same manner as Battery A except that a screen was not used on one side of the electrode.

The discharge capacity of the above batteries during normal charging and discharging is, for example,
When examined under the conditions of charging to 0.54 V at 0.25 mA and discharging to 0.25 V at 0.35 mA, battery A had a power of 10.5 mAh, and battery B had a power of 9.2 mAh.

Therefore, we next investigated the life characteristics of each battery under these charging and discharging conditions. In each case, 10 cells were used.

The ambient temperature was 45°C. As a result, the number of cycles at which the discharge capacity deteriorated to 60% of its initial value was 1100 for battery A.
~1200 cycles compared to 95 cycles for battery B.
It was 0-1050 cycles.

As is clear from this result, battery A had a longer life.

In addition, although the previous example showed the results of using a polyethylene screen as a porous body in the electrode layer, it was confirmed that this porous body had similarly excellent performance in the electrolyte layer.

In addition, although a screen was used as the porous body in the example,
In addition, punched metal or expanded metal materials may also be used, and materials such as other thermoplastic resins such as polyvinyl chloride, polyacrylic resins, and polyamides may also be used.
I don't care.

Effects of the Invention The present invention provides a positive electrode layer and a negative electrode layer on one side of the positive electrode layer and the negative electrode layer.
In the case of an electrolyte layer, a porous body made of thermoplastic resin is placed on both sides, at least on one side, and both electrode layers and the electrolyte layer are integrated under pressure at a temperature at or above the temperature at which the porous body softens and melts. This improves the adhesion of the joint between both electrode layers and the electrolyte layer. As a result, the discharge capacity, self-discharge characteristics, cycle life, etc. of the solid-state secondary battery can be improved.

Claims (3)

[Claims] (1) In the manufacturing method of a solid-state secondary battery, the positive and A layer consisting mainly of negative electrode material and a binder is formed on a porous body made of thermoplastic resin, and the surface where this porous body is brought into contact with an electrolyte layer to integrate it, and this porous body softens and melts. A method for manufacturing a solid-state secondary battery characterized by pressurizing and integrating it at or above a temperature. (2) In the manufacturing method of a solid-state secondary battery, a layer mainly containing an electrode material and a binder is arranged on both sides, and a layer mainly containing an electrolyte and a binder is placed in the center, and the electrolyte and the binder are integrated by heating. A porous body made of thermoplastic resin is placed on both sides of a layer mainly containing a binder, and the electrolyte layer and both electrode layers are integrated under pressure at a temperature at which the porous body softens and melts or at a temperature higher than that. A method for manufacturing a solid-state secondary battery characterized by the following. (3) The method for producing a solid secondary battery according to claim 1 or 2, wherein the porous body is in the form of a screen, punched metal, or expanded metal.