JPH02162659A - Manufacture of solid secondary battery - Google Patents

Abstract

PURPOSE:To strongly bond electrode layers to an electrolyte layer and to retard expansion in charge-discharge by unitedly arranging electrode layers on both sides of an electrolyte, and by impregnating a binder solution, then drying. CONSTITUTION:For example, Cu2Mo6S6 is used as positive and negative layers and an electrolyte layer made of RbCu4I1.5Cl3.2 is placed between both electrodes, then they are united with a hot press. A binder prepared by dissolving polycyanoacrylate resin in toluene so as to have a specified wt.% is impregnated into the cell element. By drying the cell element, the electrodes are strongly bonded to the electrolyte layer, and expansion in charge-discharge is retarded. A solid secondary battery having high performance is obtained.

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 supplies, so-called solid-state batteries, whose constituent materials are all solid, are used as primary and secondary batteries because they do not leak, are expected to be highly reliable, and can be made smaller and lighter. Both batteries have received attention. Currently, it is mainly being considered for memory backup of various devices.

In this solid-state battery, a solid electrolyte for moving ions within the battery is particularly important, and Lll, Li3N, etc.
i+ ion conductive solid electrolyte, RbA g 415, A
Ag+ ion conductive solid electrolyte such as g l-Ag2O, Ag I Mo O3, H+ ion conductive solid electrolyte and Rb Cu411.5cl 3.5, C
Cu+ ion conductive solid electrolytes such as u [-Cu20-M o 03 and the like have been taken up.

In addition, CuOoIT I S2, A
go, 1T I S2, CuO, IN b S2, Ag
o, 1N b S2, WO-3 and Cu yMo
Shell phase compounds such as 6S e-z and FeyMQ6Se-z are listed. − side, Cu s A on the negative electrode
g-, Lls-5WO3, and shell phase compounds similar to those for positive electrodes have been tried.

Ru.

The structure of these batteries is similar to that of other batteries, with layers containing mainly electrode active materials and binders as positive and negative electrodes on both sides, and a layer containing mainly electrolyte and binder in the center. Common. There are various methods for current collection, but one effective method is to provide a conductive layer containing a binder on the outside.

Problems to be Solved by the Invention When a solid secondary battery having such a configuration was manufactured and charged and discharged, a decrease in capacity was observed after a relatively small number of cycles, although it depended on the conditions. That is, when charging and discharging were repeated, internal resistance increased and performance deteriorated. As a result of investigating the cause, it was found that in this battery as well as in other batteries that use a solution as an electrolyte, the electrodes in particular expand even slightly during the charging and discharging process.

In the case of conventional batteries that use a solution as the electrolyte, the solution enters the electrode, and this is a major cause of expansion, which is often so noticeable that it can be clearly observed from the outside.In contrast, in solid secondary batteries, Since there is no solution present, there is no observable expansion. However, if there is even a slight expansion, there is a problem in that internal resistance increases and various performances deteriorate because there is no solution.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention arranges layers mainly composed of electrode materials on both sides and a layer mainly composed of electrolyte in the center, integrates the two, and binds them together after integration. It is characterized by impregnating with a chemical solution and drying.

As a further preferred invention, layers mainly containing electrode material and a binder are arranged on both sides, and a layer mainly containing an electrolyte and a binder is arranged in the center, and the layers are integrated by heating, and after the integration, impregnated with a binder solution. There is manufacturing, drying. As the binder, polyethylene, polyvinyl chloride, polyacrylic resin, polystyrene resin, etc. are used by dissolving each in a solvent.

According to a manufacturing method that adds a step of impregnating a binder solution and drying after integrating a layer mainly containing a working electrode material and a layer mainly containing an electrolyte, for example, a simple electrode or an electrolyte, which has been commonly used in the past, can be used. Compared to the case where a binder is added inside, a solid secondary battery can be obtained with the electrode and electrolyte layers firmly attached, which suppresses the slight expansion that occurs during the charging and discharging process.
Therefore, excellent discharge performance and self-discharge properties can be obtained without increasing internal resistance, and furthermore, the capacity does not decrease even with a relatively small number of cycles. In addition, according to the manufacturing method, the electrode material is prepared by disposing a layer mainly containing a binder on both sides and a layer mainly containing an electrolyte and an adhesive in the center, and then further impregnating with a binder solution and drying after integration. The action and effect of the binder is further improved, and performance can be improved.

Example A copper shell (Cu2Mo65B) was used as the positive electrode material, 20 wt% of RbCu411.5CI3.5 was used as the electrolyte, and 6 wt% of commercially available polyethylene was used as the binder.
%, add the hot benzene solution, stir thoroughly, and leave in a semi-dry state.

On the other hand, the negative electrode also uses a copper shell (Cu2Mo65B) and the same electrolyte Rb Cu4r 1.5c13.
5 with 20 wt% and a binder (6 wt%), and leave it in a semi-dry state. Plus RbCua 11.5C as an electrolyte
I 3.5, also with polyethylene 6 as a binder.
Add it so that it becomes wt% and keep it in a semi-dry state.

Next, a mold with a diameter of 20 mm was filled with 0.6 g and 1 g of Ig for the positive electrode, electrolyte, and negative electrode in that order, respectively, and this was first heated to 160°C using a press machine to produce 500 kg/c.
It was pressurized under conditions of m 2 and taken out from the mold. Next, the battery element thus obtained was immersed in an 8 wt % toluene solution of polycyanoacrylate resin, and then dried at 70°C. A commercially available carbon film containing fine carbon black powder dispersed in rubber was applied as a current collector to both sides of the film, and then a film with a thickness of 0.3 mm was
120℃, 500Kg by applying a Cu plate with a diameter of 26mm
The pressure was applied and paused under the condition of /cm2. The surrounding area of the battery was first coated with a polyacrylic resin, and then a cold-curing epoxy resin was applied thereon to construct the battery. This battery is called A.

Next, for comparison, a battery obtained by the same process as A was added as B, except that the battery element was not immersed in the polycyanoacrylate resin solution and dried.

First, the discharge voltage and capacity during normal charging and discharging of the above two batteries were compared. When charging to 0°52V at 1.0mA and discharging to 0.3V at 2.5mA,
At A, the average voltage is 0.47V and the discharge capacity is 17.5mA.
h, whereas B shows 0.44V and 1, respectively.
6.4 mAh, and A was superior in all cases. .

Therefore, we next investigated the self-discharge characteristics of each battery under these charging and discharging conditions. After charging to 0.55V and leaving at 25° C. for one month, the capacity was examined and found that the retention rate was 97% for A, but 89% for B.

Finally, the life characteristics of the two batteries were investigated. For each battery, 10 cells were used and the zero ambient temperature was 25°C. As a result, the number of cycles at which the discharge capacity deteriorated to 60% of the initial value was 870 to 960 cycles for A.
B was 620 to 760 cycles. As is clear from this result, A had a long life.

In this type of battery, the electrodes seem to have a tendency to expand slightly during the charging and discharging process, which obstructs the flow of ions during charging and discharging, leading to a decrease in voltage and capacity, and furthermore, the capacity decreases in a relatively small number of cycles. This is the cause of the decline. However, in A of the present application, a battery is obtained with the electrode and electrolyte layer firmly bonded, which suppresses the phenomenon of expansion during the charging and discharging process, and therefore provides excellent discharge characteristics without increasing internal resistance. Moreover, the capacity does not decrease even after a relatively small number of cycles.

Effects of the Invention In the manufacturing method of a solid state secondary battery, a layer mainly composed of electrode material is arranged on both sides, a layer mainly composed of electrolyte is arranged in the center, the two are integrated, and after integration, impregnated with a binder solution, By adding the drying step, the increase in internal resistance during charging and discharging of the battery is suppressed, and therefore, excellent discharge performance and self-discharge characteristics are obtained, and a longer life is possible. In addition, the above effects can be further enhanced by manufacturing a solid secondary battery in which electrode materials and a binder are mainly arranged, integrated by heating, and then further impregnated with a binder solution and dried after integration. be able to.

Claims (3)

[Claims] (1) A solid characterized by having layers mainly composed of electrode materials on both sides and a layer mainly composed of electrolyte in the center, integrating the two, impregnating with a binder solution after integrating, and drying. Manufacturing method for secondary batteries. (2) Layers mainly composed of electrode materials and binders are placed on both sides, and a layer mainly composed of electrolyte and binder is placed in the center, integrated by heating, and then further impregnated with a binder solution. A method for manufacturing a solid-state secondary battery characterized by drying. (3) The method for producing a solid secondary battery according to claim 1 or 2, wherein the electrode material is a copper shell structure, the electrolyte is a copper ion conductor, and the binder is a thermoplastic resin.