JPH053050A - Operation method for solid secondary battery and power supply - Google Patents

Abstract

PURPOSE:To allow voltage to become lower as temperature rises for longer service life in a solid secondary battery wherein a copper cheverl phase compound is used as positive and a negative electrodes and a Rb series ionic conductive solid electrode is used as a solid electrolyte. CONSTITUTION:A solid secondary battery is formed by using a copper chevrel phase compound as positive and negative electrode materials and a Rb series ionic conductive solid electrolyte as a solid electrolyte. As for this battery, overcharge occurs if it is constantly charged with a set potential of 0.5 to 0.6V. And the higher the ambient temperture, the higher leakage current and the less capacity. Therefore, at the room temperature, charging is carried out with 0.6V while at high temperatures such as 100 deg.C, with a lower set voltage such as 0.52V. This constitution allows controlling the increase of leakage current at high temperatures and also allows the battery to live longer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a secondary battery and a power supply device, and more particularly to an operation method and a power supply device of a so-called solid secondary battery whose constituent materials are all solid.

[0002]

2. Description of the Related Art Among batteries used as various power sources, so-called solid-state batteries whose constituent materials are all solid have no liquid leakage. Therefore, both primary and secondary batteries have been attracting attention for any reason that they can be expected to have high reliability and can be made smaller and lighter. Currently, it is mainly used for memory backup of various devices.

In solid-state batteries, Li ⁺ ion conductive solid electrolyte, Ag ⁺ ion conductive solid electrolyte, H ⁺ ion conductive solid electrolyte and RbCu ₄ I _1.5 Cl _3.5 ,
Cu ⁺ ion conductive solid electrolytes such as CuI-Cu ₂ O-MoO ₃ have been taken up.

Further, as a material for the positive electrode, CuTi system, Ag
Ti-based compounds and Chevrel phase compounds such as Cu _y Mo ₆ S _8-z and Fe _y Mo ₆ S _8-z (however, y = 0 to 4, z = 0 to 0.4) are mentioned. On the other hand, Cu, Ag, Li _1.5 WO ₃ and the same Chevrel phase compound as for the positive electrode have been tried as the negative electrode material.

Of these, a copper Chevrel phase compound is selected for the positive electrode and the negative electrode, and in particular, a solid secondary battery using the composition of Cu ₂ Mo ₆ S ₈ for both electrodes and an Rb-based ion conductive solid electrolyte as the solid electrolyte is used. As compared with other systems, it can be charged and discharged quickly, has a long life, and has good over-discharge characteristics.
However, its energy density is lower than that of other general-purpose batteries, so it is mainly used for memory backup.

Therefore, as a general charging method in actual use, constant voltage charging is continuously performed and discharging is performed as necessary. At this time, the charge potential is set to 0.50 to 0.60 V / cell as an upper limit in order to avoid deterioration of the electrolyte and electrodes.

[0007]

As a material for the positive electrode and the negative electrode, a copper Chebrel phase compound excellent in high discharge and reversibility is selected, and particularly, a composition of Cu ₂ Mo ₆ S ₈ is used for both electrodes.
Similar to other batteries, a solid secondary battery using an Rb-based ionic conductive solid electrolyte such as RbCu ₄ I _1.5 Cl _3.5 as a solid electrolyte is required to have excellent temperature characteristics like other batteries. However, there has been a battery in which a decrease in discharge capacity is observed when constant voltage charging is continuously performed at a high temperature of 60 ° C. or higher. The present invention solves such a problem, and an object of the present invention is to provide an operating method and a power supply device of a solid secondary battery having a high temperature and a long life.

[0008]

In order to solve this problem, a method for operating a solid secondary battery and a power supply device of the present invention include a copper chevrel phase compound, especially C, as a material for a positive electrode and a negative electrode.
Select the composition of u ₂ Mo ₆ S ₈ and use RbCu ₄ as the solid electrolyte.
In a solid-state secondary battery that is used by always performing constant-potential charging using an Rb-based ionic conductive solid electrolyte such as I _1.5 Cl _3.5 , the higher the temperature, the lower the potential during charging. Moreover, constant-potential charging is always performed by the power supply device including the charger controlled in this way.

[0009]

According to this method or configuration, the solid secondary battery operating method and power supply device of the present invention use the composition of the copper Chevrel phase compound Cu ₂ Mo ₆ S ₈ as both the positive electrode and the negative electrode material, and use it as the solid electrolyte. In a solid secondary battery using an Rb-based ion conductive solid electrolyte, 0.50 to 0.6
0V / cell has been used as the set potential for charging. However, especially when constantly charged with a constant potential for memory backup, the battery is overcharged and the leakage current increases when the ambient temperature rises, and the capacity decreases when the battery is intermittently discharged. Therefore, it may be charged at 0.6V / cell at room temperature, but at a high temperature, for example, 100 ° C, by setting a low set potential such as 0.52V / cell, the increase in leakage current at high temperature can be controlled and a long life can be achieved. become.

Further, by using the constant potential charger constructed under the above conditions, it is possible to achieve a long life at high temperature.

[0011]

EXAMPLE An operation method and a power supply device for a solid secondary battery according to an example of the present invention will be described below.

Copper chevrel (Cu ₂ Mo ₆ S ₈ ) was used as the material for the positive electrode and the negative electrode, and RbC was used as the electrolyte for this.
u ₄ I _1.5 Cl _3.5 is 20 Wt% and commercially available polyethylene is 6 Wt% as a binder, and the thickness is 300 μm.
Create a sheet of.

RbCu ₄ I _1.5 Cl _3.5 is used as an electrolyte, and polyethylene is also added as an adhesive in an amount of 13 wt% to prepare a sheet having a thickness of 120 μm. Next, the positive electrode, the electrolyte, and the negative electrode are stacked in this order, and this is first pressed with a press machine heated to 160 ° C. under the condition of 500 kg / cm ² . Then, conductive carbon paper molded with a commercially available binder was applied to both sides of the battery element thus obtained, and pressure integrated under conditions of 130 ° C. and 400 kg / cm ² to obtain a battery element.

Further, a 0.2 mm-thick laminated sheet made of aluminum with a polyethylene film is applied to both sides of the battery element with polyethylene on the inside, and a roller press machine heated to 140 ° C. is used at both the battery element portion and the battery periphery for 30 minutes.
Pressurize under heating to 0 kg / cm ² . By this operation, the battery element is pressurized, and polyethylene is welded around the battery to complete the sealing. Regarding the lead plates, in this embodiment, thin Cu plates were taken out to the outside. The size of the battery was 15 × 30 mm.

After completion of the chemical conversion, this battery was heated to 0.58 at 20 ° C.
The battery was constantly charged with a constant voltage charger controlled to be 0.56 V at V and 60 ° C. and 0.52 V at 100 ° C. This battery is designated as A. The discharge was carried out by performing constant current discharge at 0.5 mA up to 0.3 V every 500 hours of charge at the same temperature as the charge.

For comparison, all temperatures are 0.58 V
A battery subjected to constant voltage charging was added as B, a battery subjected to constant voltage charging at 0.56 V was added as C, and a battery similarly subjected to constant voltage charging at 0.52 V was added as D.

With the above batteries A to D, the ambient temperature was 20 ° C. and 6
The charging / discharging cycle was repeated at 5 ° C. and 100 ° C. to examine the life. The results of charge / discharge cycle and capacity (mAh) at 20 ° C. are shown in (Table 1), the results at 65 ° C. are shown in (Table 2), and the results at 100 ° C. are shown in (Table 3).

[0018]

[Table 1]

As is clear from the results shown in Table 1, the temperature is 20 ° C.
At room temperature in the vicinity, when the set voltage is increased, the initial capacity is large.

At the next 65 ° C., as shown in Table 2, when the set voltage is low as shown by D, the discharge capacity is small from the beginning of the charge / discharge cycle. Further, if the set voltage is too high as in B, the life is shortened.

[0021]

[Table 2]

Finally, at 100 ° C., as shown in Table 3, B,
When the set voltage is high like C, the discharge capacity is large, but the decrease due to the charge / discharge cycle is large.

[0023]

[Table 3]

[0024]

As is apparent from the above description of the embodiments, according to the method for operating a solid secondary battery and the power supply device of the present invention, a copper chevrel phase compound, particularly Cu ₂ Mo ₆ S, is used as a material for the positive electrode and the negative electrode. Select a composition of ₈ and use a Rb-based ionic conductive solid electrolyte such as RbCu ₄ I _1.5 Cl _3.5 as a solid electrolyte to charge the battery at a constant voltage all the time. Low potential charging. In addition, by charging with a charger controlled in this way, a long life can be achieved especially at high temperatures.

Claims (3)

[Claims] 1. A copper chevrel phase compound as a material for a positive electrode and a negative electrode, and RbCu ₄ I _1.5 Cl _3.5 as a solid electrolyte.
A method for operating a solid-state secondary battery, in which the potential at the time of charging is lowered as the temperature rises in a solid-state secondary battery that is always charged with a constant potential using an Rb-based ion conductive solid electrolyte such as. 2. A copper Chevrel phase compound as a material for a positive electrode and a negative electrode, and RbCu ₄ I _1.5 Cl _3.5 as a solid electrolyte.
In a solid state secondary battery which is always charged with a constant potential using an Rb-based ion conductive solid electrolyte such as a solid state equipped with a constant potential charger controlled to lower the potential during charging as the temperature rises. Secondary battery power supply. 3. The set potential near room temperature is 0.58 to 0.
The operating method and power supply device for a solid secondary battery according to claim 1 or 2, wherein the voltage is 60 V and 0.50 to 0.53 V at 100 ° C.