JPH02114460A - Manufacture of solid secondary battery - Google Patents

Abstract

PURPOSE:To provide excellent discharging performance and self-discharging characteristics and prolong the lifetime by heating a layer chiefly containing an electrode material and binder and a layer majorly including an electrolyte and binder, which are thus consolidated, and forming a battery using thin sheets of metal and resin as a battery jar. CONSTITUTION:Layers consisting of an electrode material with or without binder are arranged on both sides while a layer consisting of electrolyte with or without binder put in the middle, and they are consolidated by means, for ex., of heating, and then metal and resin films used in a thin type lithium battery are used as a battery jar, whose periphery is hot welded to form a battery. Thus a battery is obtained in the condition that layers of electrode and electrolyte are in pressure contact firmly, which suppresses phenomenon of expanding to any minor degree during charging/discharging, precludes increase in the internal resistance, and prevents deterioration of electrolyte due to moisture from atmosphere. Thus excellent discharging performance and self-discharging property are obtained, and the capacity will not drop at a comparatively small cyclic number.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to 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.
l+ ion conductive solid electrolyte, RbAg415, Ag
Ag+ ion conductive solid electrolyte such as l-Ag2O, -Mo03, H1 ion conductive solid electrolyte and RbCu
Cu+ ion conductive solid electrolytes such as 411,5CI3.5 and Cu1-Cu20-MoO3 have been taken up.

In addition, as positive electrode materials, CLlo, 1'r l S2
, Ago, IT I S2, CuO, INbS2, Ag
o, 1NbS2, WO3 and Cu, Mo6s8-,,
Chevrel phase compounds such as F e and M 065B-z are mentioned.

On the other hand, for the negative electrode, attempts have been made to use Cu, Ag%L i 1,5WO3, and the same Chevrel phase compound as for the positive electrode.

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, the electrodes in particular expand even slightly during the charging and discharging process, similar to other batteries that use a solution as the electrolyte. In the case of a battery using such a solution, the solution is a major cause of expansion, which can be clearly observed from the external appearance.

On the other hand, in a solid-state secondary battery, there is no solution, so there is no observable expansion.However, if there is even a slight expansion, the internal resistance increases because there is no solution, causing various problems. Performance deteriorates. Furthermore, RbCu411 is a promising electrolyte in terms of discharge characteristics and lifespan.
．． Cu+ ion conductive solid electrolyte such as 5CI3.5, Cu yM Oa S as material for positive electrode and negative electrode.
When a Chevrel phase compound such as [1-z is used, there is a problem that adverse effects such as deterioration of electrodes and electrolyte materials due to moisture in the atmosphere are likely to occur.

Means for Solving the Problem: Electrode material or a layer of this with a binder added to it is placed on both sides, and an electrolyte or a layer of this with a binder added to the center, and after being integrated by heating, for example, a thin The battery is constructed by using a thin film made of metal and resin, which is used in lithium batteries, etc., as a battery case, and heating and fusing the surrounding area. The metal here is aluminum.

Thin sheets of copper, nickel, stainless steel, titanium, etc. and polyolefins such as polyethylene and polypropylene are preferable as the resin.

Furthermore, before the electrode is constructed, that is, when or after the electrode is integrated by heating, a step is added in which two plates are placed on both outer surfaces of the electrode and the two plates are bonded at the battery periphery. In this case, the plate may be a current collector or may be arranged separately. For this adhesion, thermoplastic resins are preferably used, such as polyethylene, polyvinyl chloride, polyacrylic resins, polystyrene resins, and the like.

A layer of the working electrode material or a binder added thereto is placed on both sides, and a layer of electrolyte or a binder added to the same is placed in the center, and when the electrode is fixed together, it is preferable to have plates on both outer surfaces of the electrode. Arranged,
After adding a step of adhering these two plates at the battery periphery, a thin plate made of metal and resin is used as a battery case, and the battery is constructed by adhering, particularly heat-sealing, at the battery periphery. As a result, in the present application, a battery can be obtained in which the electrode and electrolyte layers are firmly bonded, so that the phenomenon of expansion even slightly during the charging and discharging process is suppressed, and therefore the internal resistance does not increase and the battery can be easily compressed. Since deterioration of the electrolyte due to moisture from the atmosphere can also be prevented, excellent discharge performance and self-destruction properties can be obtained, and furthermore, the capacity does not decrease with a relatively small number of cycles.

Example: Copper Chevrell (Cu2Moese) was used as the material for the positive electrode, and Rb Cu411,5C! was used as the electrolyte. 3
．． A tetrahydrofuran solution was added so that 20 wt % of 5 and 6 wt % of commercially available polyvinyl chloride as a binder were added, stirred thoroughly, and left in a semi-dry state.

On the other hand, copper Chevrell (Cu2MOaSa) was used for the negative electrode, and electrolyte RbCu41. ．． A tetrahydrofuran solution of 20 wt% of 5C13゜5 and 8 wt% of polyvinyl chloride as a binder was added, stirred thoroughly, and left in a semi-dry state, and RbCu41+, 5C13,5 was used as an electrolyte. A warm benzene solution of polyethylene as a binder was added so that the concentration was 8 wt %, and the mixture was left in a semi-dry state.

Next, 1 g, 0.6 g, and 1 g of the positive electrode, electrolyte, and negative electrode were filled in a mold with a diameter of 20 mm in that order, and this was first pressed to 500 kg/cm using a press heated to 1608 C.
Pressure was applied under the conditions of 2, and then a commercially available carbon film in which fine carbon black powder was dispersed in a tum was applied as a current collector to both sides of the film, and then a film with a thickness of 0.3
120°C, 500 with a Cu plate of 26mm in diameter.
It was fixed under pressure under the conditions of Kg/cm2. This is sandwiched between two 0.05 mm thick aluminum plates that are integrated with a 0.10 mm thick polyethylene film in the area corresponding to the battery periphery, and the inner polyethylene film is removed from above the aluminum plate. A battery was constructed by heat-sealing. Note that the Cu plate and the aluminum plate were adhesively fixed with a conductive adhesive.

This battery is called A.

Next, for comparison, 1 g, 0.6 g, and 1 g of positive electrode, electrolyte, and negative electrode were filled in the mold in that order, and the mold was pressurized at 500 kg/cm2 with a press machine without heating. After applying a carbon film as a current collector to both sides, a Cu plate was applied to the outside of the current collector, and 500 kg/
The pressure was fixed under the condition of cm2. A battery was then constructed by heat-sealing an inner polyethylene film onto the outer aluminum plate. This was added as B.

First, the discharge voltage and capacity during normal charging and discharging of the above two batteries were compared. When charging to 0°52V at 0.10mA and discharging to 0.3μ at 0.3mA, the average voltage at A was 0.48μ and the discharge capacity was 18.5
mAh, whereas in B each 0.45V
, 16.4mAh, and A was excellent in both 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 it at 308C for one month, I checked the capacity and found that the capacity retention rate was 97.3 for A.
%, but in B it was 90°1%.

Finally, the life characteristics of the two batteries were investigated. In each case, 10 cells were used. The 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 1050 to 1100 cycles for A, while it was 650 to 750 cycles for B. As is clear from this result, A had a long life.

Note that although the embodiments have been shown using a single cell as an example, the same method can be used for a battery having a laminated structure that is used to increase capacity or voltage.

Effects of the Invention Preferably, when an electrode material or a layer of the electrode material with a binder added thereto is placed on both sides, and an electrolyte or a layer of the electrolyte with a binder added is placed in the center, and the electrode material is integrated by heating, for example, A plate is placed on the external side of the wound, and the two plates are glued together around the battery. Then, a thin plate made of metal and resin is used as a battery case, and the area around it is heated and fused. Configure. These features particularly suppress the expansion of the electrodes during the charging and discharging process, thereby suppressing the increase in internal resistance of the battery during charging and discharging, and furthermore, making it possible to eliminate the negative effects of moisture in the atmosphere. It is possible to obtain better discharge performance and self-discharge characteristics, and also to extend the service life.

Claims (5)

[Claims] (1) Layers mainly composed of electrode materials and binders are arranged on both sides, and layers mainly composed of electrolyte and binders are arranged in the center. After being integrated by heating, a thin plate made of metal and resin is 1. A method for manufacturing a solid-state secondary battery, characterized in that the battery is constructed by using the tank as a tank and heat-sealing the periphery of the tank. (2) In a battery that has layers mainly composed of electrode materials on both sides and a layer mainly composed of electrolyte in the center, two plates are arranged on both outer sides of the battery, and these two plates are arranged on both sides of the battery. Manufacture of a solid-state secondary battery characterized in that a battery is constructed by using a thin plate made of metal and resin as a battery case and heat-sealing the periphery of the battery after adding a process of gluing the plate at the battery periphery. Law. (3) The method for manufacturing a solid secondary battery according to claim 1 or 2, wherein the battery has a laminated structure. (4) Claim 1 or 2, wherein the electrode material is a copper Chevrel structure, the electrolyte is a copper ion conductor, particularly a RuCu_4I_xCl_y solid electrolyte, and the binder contained therein is a thermoplastic resin. A method for manufacturing solid-state secondary batteries. (5) The method for producing a solid secondary battery according to claim 1 or 2, wherein the metal is a thin film of aluminum, copper, nickel, stainless steel, titanium, etc., and the resin is a polyolefin-based thin film.