JPH0481309B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an all-solid-state solid electrolyte secondary battery using a solid electrolyte having high ionic conductivity at room temperature. Structure of conventional examples and their problems Batteries that use solid electrolytes that have high ionic conductivity at room temperature can be made into an all-solid-state battery, so there is no leakage and there is very little self-discharge during storage. This results in a battery with high reliability. In the field of microcoelectronics, which is characterized by miniaturization of electric circuit elements, it is natural that batteries, which are one of the power sources, must also be miniaturized. 1
For primary batteries, whose lifespan ends after one discharge, the smaller the battery is made, the less it will be able to supply the necessary capacity as a power source for devices, and this will reach the limit of battery miniaturization. One way to solve such problems is to
There is a way to use a secondary battery in combination with an external power source such as a solar battery. Conventionally, secondary batteries for such uses include nickel-cadmium batteries, as proposed in U.S. Patent No. 3,906,051,
There are batteries that use TiS ₂ as the positive electrode active material, but these are batteries that exclusively use a liquid electrolyte.
Since a liquid is used, a battery container made of metal or the like must be used, and there is a limit to miniaturization due to the container processing. For example, the thickness is at most 2 mm, and the outer diameter is about 7 mm. That's it. Purpose of the Invention An object of the present invention is to provide a solid electrolyte secondary battery having a novel positive electrode active material that can be extremely easily made small and thin, has no leakage in principle, and has excellent charge/discharge characteristics. With the goal. Structure of the Invention The solid electrolyte secondary battery of the present invention has (Cu, Ag) _o .
A new chalcogenide represented _{by TiM}
A metal element having a trivalent valence in the chalcogenide, C: an element selected from S, Se, Te, x:
0.01~0.2, n: 0.05~0.2) and a conductive solid electrolyte containing copper ions (Cu ⁺ ) or silver ions (Ag ⁺ ); It is composed of a conductive solid electrolyte layer and an electrode layer consisting of a reversible copper or silver negative electrode, for example, a mixture of metallic copper powder or metallic silver powder and a copper ion conductive or silver ion conductive solid electrolyte. Description of Examples First, reactions in Examples of the present invention will be described. The battery reaction at the positive electrode is Cu _o TiM _x C _2+1.5x +δCu ⁺ +δe ^-Discharge and charge Cu _o+ 〓TiM _x C _2+1.5x (When using a copper ion conductive solid electrolyte and a copper negative electrode...Hereinafter referred to as copper-based Ag _o TiM _x C _2+1.5x +δAg ⁺ +δe ^-Discharge/ Charge Ag _o+ 〓TiM _x C _2+1.5x (When using a silver ion conductive solid electrolyte and a silver negative electrode...hereinafter referred to as silver-based) It is expressed as The battery reaction of the negative electrode is expressed as δCu charge = discharge δCu ⁺ δe ^- (copper-based) δAg charge = discharge δAg ⁺ δe ^- (silver-based). Battery voltage is regardless of copper type or silver type (Cu, Ag)
The value of n・TiM _x C _2+1.5x is in the range of 0.01 to 0.2 and n
The value ranges from 0.05 to 0.2 and varies between 0.52V and 0.45V. The amount of current that can be extracted from a battery is determined by the thickness of the solid electrolyte used, the area of the electrolyte layer in contact with the positive and negative electrodes, and the ionic conductivity of the electrolyte. As the copper ion conductive solid electrolyte, N,
CuBr series doped with N′-dimethyltriethylenediamine dibromide, 7CuBr・C ₆ H ₅ N ₄ CH ₃
Br or RbCu ₄ I _2-y C _3+y system can be used. Among these, especially RbCu ₄ I _2-y C
_3+y system is positive electrode active material (Cu, Ag) _o
Even if it is in contact with TiM _x C _2+1.5x for a long time, it is difficult to cause chemical changes, so it is suitable for batteries that will be used for a long time.
It can be used most suitably. As the silver ion conductive solid electrolyte, Ag ₃ SI,
RbAg ₄ I ₅ , RbAg ₄ I ₅ (SiO ₂ dispersed), etc. can be used. FIG. 1 shows a cross-sectional view of a solid electrolyte secondary battery used to examine the effects of the present invention, where 1 is a positive electrode layer;
2 is a solid electrolyte layer, 3 is a negative electrode layer, 4 is a current collector, 5
is an electrode lead, and 6 is a plastic package. The positive electrode active material (Cu,Ag)TiM _x C _2+1.5x is mixed with metal Cu powder or metal Ag powder in a predetermined ratio.
TiC ₂ and M ₂ C ₃ mixed press molded, in some cases, metal Cu powder or metal Ag powder and metal
Ti powder, metal M' powder (Cr, A, Co, Fe), and chalcogen powder C (S, Se, Te) are mixed in a predetermined ratio and press-molded, then vacuum sealed in a quartz tube. It can be obtained by heating reaction at ℃ to 800℃ for 72 hours. A positive electrode mixture powder obtained by mixing the positive electrode active material powder and the solid electrolyte powder obtained in this way, a negative electrode mixture powder obtained by mixing the solid electrolyte powder, the negative electrode active material powder, and the solid electrolyte powder. By press-pressing in layers to form battery pellets, then bonding a current collector and electrode leads to the positive and negative electrode sides, and then coating the entire battery with a thermosetting resin or an ultraviolet curable resin. Batteries are provided. [Example 1] Electrolyte: 0.05 gr of RbCu ₄ I _1.5 C _3.5 Negative electrode mixture: 80 wt% Cu and 20 wt% Cu ₂ S mixture
A mixture of 4.75 parts by weight and 1.25 parts by weight of the electrolyte
0.20gr Positive electrode mixture: 0.05gr of a mixture of 1 part by weight of the active material shown in Table 1 and ¹ part by weight of the above-mentioned electrolyte. Structure like 7mm in diameter and 0.8mm in thickness
Assembled a copper-based battery. Discharge these batteries at room temperature with a current value of 100μA1
The battery performance was evaluated by repeating charging and discharging for 2 hours in one cycle of charging for 1 hour. Table 1 shows the value of change in battery voltage per unit of electricity obtained from the voltage during discharge at the 50th cycle = polarization value (V/
Give these battery performance as (mAh). Polarization value = (Battery voltage (V) 15 minutes after starting discharge) -
(Battery voltage (V) 45 minutes after discharge starts) / 0.05 The battery having the novel positive electrode active material according to the present invention has a higher polarization than the conventionally proposed battery using TiS ₂ as the positive electrode active material. The value is small, indicating that the battery has excellent charging and discharging characteristics. FIG. 2 shows the relationship between the number of charge/discharge cycles and _the battery voltage at the end of discharge for each number of cycles in the charge/discharge test of the copper-based battery using the positive electrode active material Cu _0.1 TiCr _0.01 S 2.015. [Example 2] Electrolyte: 0.05 gr of RbAg ₄ I ₅ (SiO ₂ dispersed) Negative electrode mixture: 0.1 gr of a mixture of 4 parts by weight of 325 mesh pass 100% Ag powder and 1 part by weight of the electrolyte Positive electrode mixture: Table 2 A mixture of 1 part by weight of the active material shown in Figure 1 and 1 part by weight of the electrolyte was molded under pressure at a pressure of 2 tons/ ^cm2 . mm
Assembled a silver-based battery. These batteries were subjected to charge/discharge tests similar to those shown in Example 1 to evaluate battery performance. 1st
The table gives the polarization values during discharge at the 50th cycle. It can be seen that the battery having the novel positive electrode active material according to the present invention has a smaller polarization value and is superior to the battery using the conventionally proposed TiS ₂ as the positive electrode active material. Figure 2 shows the relationship between the number of charge/discharge cycles and the battery voltage at the end of discharge of each cycle in the charge/discharge test of the silver-based battery using Ag _0.2 TiCr _0.02 S _2.03 as the positive electrode active material. .

【table】

【table】

[Example 3]

Electrolyte: 0.05 gr of RbCu ₄ I _1.25 C _3.75 Negative electrode mixture: 0.20 gr of a mixture of 4.75 parts by weight of a mixture of 60% by weight Cu and 40% by weight of Cu ₂ S and 1.25 parts by weight of the above electrolyte Positive electrode mixture: 0.20gr of a mixture of 1.25 parts by weight of the above electrolyte A mixture of 1 part by weight of the substance and 1 part by weight of the above electrolyte was press-molded with 0.05 gr of the above material at a pressure of 2 tons/cm ² to form a structure as shown in Figure 1 with a diameter of 7 mm and a thickness of 0.8 mm.
assembled a copper-based battery. These batteries were subjected to a charge/discharge test similar to that shown in Example 1 to evaluate battery performance. Third
The table gives the polarization values during discharge at the 50th cycle. It can be seen that the battery having the novel positive electrode active material according to the present invention has a smaller polarization value and is superior to the battery using the conventionally proposed TiS ₂ as the positive electrode active material.

[Example 4]

Electrolyte: 0.05gr of _RbAg4I5 Negative electrode mixture: 0.2gr of a mixture of ₄ parts by weight of 325 mesh pass 100% Ag powder and 1 part by weight of the above electrolyte Cathode mixture: 1 part by weight of the active material shown in Table 4 and the above A mixture of 1 part by weight of electrolyte and 0.05 gr of the above materials were pressure molded at a pressure of 2 tons/cm ² to form a structure as shown in Figure 1 with a diameter of 7 mm and a thickness of 0.7 mm.
Assembled a silver-based battery. These batteries were subjected to a charge/discharge test similar to that shown in Example 1 to evaluate battery performance. Fourth
The table gives the polarization values during discharge at the 50th cycle. It can be seen that the battery having the novel positive electrode active material according to the present invention has a smaller polarization value and is superior to the battery using the conventionally proposed TiS ₂ as the positive electrode active material.

[Table] Effects of the Invention According to the present invention, it is possible to obtain a small and thin practical solid electrolyte secondary battery with excellent charge/discharge characteristics.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a battery according to an embodiment of the present invention;
FIG. 2 is a diagram showing the relationship between battery discharge voltage and the number of charging/discharging cycles. 1... Positive electrode, 2... Electrolyte layer, 3... Negative electrode.

Claims (1)

[Claims] 1. A negative electrode mainly composed of metallic copper, a Cu ⁺ ion conductive solid electrolyte, and a chalcogenide represented by Cu _o TIM _x C _{2 + 1.5x} (where M: Cr, Al, Fe , Co, a metal element having a trivalent valence in the chalcogenide, C: an element selected from S, Se, Te, X: 0.01 to 0.2, n: 0.05 to 0.2). A solid electrolyte secondary battery comprising: 2 A negative electrode mainly composed of metallic silver, an Ag ⁺ ion conductive solid electrolyte, and a chalcogenide represented by Ag _o TIM _x C _{2 + 1.5x} (M: selected from Cr, Al, Fe, Co). It is characterized by being composed of a positive electrode mainly consisting of a metal element having a trivalent valence in a chalcogenide, an element selected from C: S, Se, Te, X: 0.01 to 0.2, n: 0.05 to 0.2) Solid electrolyte secondary battery.