JPS61294768A - New battery - Google Patents

Abstract

PURPOSE:To obtain a battery with good charge-discharge performance by using a positive electrode of manganese dioxide, a negative electrode of zinc, and electrolyte of zinc sulfate. CONSTITUTION:Manganese dioxide for dry battery is electrolytically manufactured from manganese sulfate solution in an acidic condition. Therefore, a MnO2-Zn battery has a possibility to be charged in an acidic solution (pH of the solution is less than 7) containing sulfate ion after discharge. When zinc sulfate solution showing acidic (for example, a 2M aqueous solution of ZnSO4 shows a pH value of 3.73) is used as electrolyte, the MnO2-Zn battery shows good rechargeability. An auxiliary electrolyte such as (NH4)2SO4 may be used.

Description

[Detailed description of the invention] A battery using manganese dioxide and zinc as positive electrode active material and negative electrode active material, respectively (hereinafter abbreviated as MnO2-Zn battery)
For example, it is widely used as a dry battery. but,
At present, this battery does not have good charge/discharge characteristics, and it has only been shown that charging is possible to some extent, mainly in batteries using an aqueous alkaline solution such as KOH as the electrolyte. (For example, R. Chemel
li et al., SecondSymposium on Ma
nganganese dioxide (1981)
October, Kyoto), Extended Abstracts
, page 57 (1980)). On the other hand, manganese dioxide for dry batteries is also produced by the electrolytic method from manganese sulfate under acidic conditions (for example, "Battery Technology", published by the Electrochemical Society Battery Technology Committee, p. 15 (October 1982)).
This indicates that it is possible to charge the above-mentioned MnO2-Zn battery under acidic conditions (the pH of the solution is 7 or less) containing sulfate ions after discharging. For example, the following reaction can be considered as a charge/discharge reaction at both the positive and negative electrodes.

Positive electrode: MnO2+SO42-+4H++2e-MnSO
4+2H2O-(1) Negative electrode: Zn+2H2OZn(OH)2+2H++2e-
-(2) Total: MnO2+Zn+SO42-+2H+M
nSO4 + Zn(OH)2- (3) In addition to the reactions shown in (1) and (2), it is said that during discharge, normally occurs on the positive electrode side of MnO2-Zn batteries (Takamura, Ogiwara, Jogami, “Batteries and Future Power Generation” edited by Institute of Electronics and Communication Engineers, p. 22) Reaction (4) 2MnO2 + 2H2
It is also conceivable that O+2e-→2MnOOH+2OH-- (4) also occurs concurrently. Under the conditions of the present invention, which uses a solution with a relatively low pH value, MnOOH produced in the reaction (4) is disproportionated to MnO2 and Mn2+ (2Mn2+).
OOH→MnO2+Mn2++2OH-) (A.E
ra et al., Electrochim. Acta, 12, 1
199 (1967)), it is conceivable that the reaction will eventually result in the reaction on the discharge side of (1). The present invention was made based on this idea, and in fact, a solution of zinc sulfate which is acidic as an electrolyte (for example, a 2M aqueous solution of ZnSO4 is
The present invention was completed based on the discovery that a MnO2-Zn battery exhibits good rechargeability when a MnO2-Zn battery (which showed a pH value of 3.73 as measured by an H meter) is used as an electrolyte. In the present invention, the battery is manufactured using ZnSO4 as the electrolyte, but it is also possible to add an auxiliary electrolyte such as (NH4)2SO4. Manganese dioxide is usually mixed with carbon such as ketstyen black or acetylene black in order to provide conductivity, but it is also possible to disperse manganese dioxide in polymer compounds such as nylon, glass, alumina, etc. An electrode material for a positive electrode may be produced in the coexistence of a substance that can be used. When fabricated in the coexistence of these substances,
Advantages were recognized in terms of the strength of the positive electrode material and the discharge characteristics of the battery. Furthermore, in the present invention, a separator such as an ion exchange membrane or a dialysis membrane is interposed between the positive electrode and the negative electrode in order to prevent performance deterioration of the positive electrode material due to charging and discharging. Efforts were also made to prevent substances that would have an adverse effect on charging and discharging from reaching the material. In the present invention, water and water containing alcohol are mainly used as the solvent for dissolving the electrolyte. others,
Water containing water-soluble compounds such as acetone and pyridine can also be used as a solvent.

Examples are shown below. Charging and discharging is done using HA- manufactured by Hokuto Denko Co., Ltd.
The charging and discharging device (having a galvanostat mechanism) controlled by a Model 301 polanciostat/galvanostat or a personal computer manufactured by NEC Corporation was used. Open circuit voltage and closed circuit voltage are the readings of these devices. In addition, when molding the positive electrode material under pressure, a hydraulic pressure machine manufactured by Riken Seiki Co., Ltd. was used. In the following examples, normally after battery fabrication, the battery is first discharged until the closed-circuit voltage reaches a predetermined voltage (0.9V in most cases), then charged, and then discharged again after this charging. Charge/discharge cycles were repeated according to the conditions. The initial value of the closed circuit voltage during discharge is usually 1.45V to 1.8V.
The average value of the closed circuit voltage during discharge is usually about 1.1
It was between 5V and 1.25V.

Example 1. 80 mg manganese dioxide (TA manufactured by Mitsui Mining & Mining Co., Ltd.)
M) and 20mg Ketuchen Black (Lion Co., Ltd.)
After mixing and grinding the commercially available carbonaceous substances in an agate mortar, the mixture is molded into a disk shape with a diameter of 13 mm under a pressure of 400 kg/cm2. This disk-shaped positive electrode material, 2M Zn
Glass fiber filter paper (GA-100 manufactured by Toyo Roshi Co., Ltd.) impregnated with 100 μl of SO4 aqueous solution was cut into a disc shape with a diameter of 13 mm.In other examples below, unless otherwise specified, GA-100 manufactured by Toyo Roshi Co., Ltd. was used as a glass fiber filter paper) and a zinc plate with a thickness of 0.4 mm were stacked, and a platinum plate as a current collector was used as a positive electrode material (the above circle in this example). The battery shown in FIG. 1 was produced by bringing the material into close contact with a plate-shaped positive electrode material. This battery is fixed as a whole by using metal fittings or the like.

When this battery was discharged at a constant current of 20 mA, the closed circuit voltage decreased to 0.9 V after 7 minutes and 5 seconds. Thereafter, this battery was charged for 15 minutes with a constant DC current of 20 mA. When the battery charged in this manner was discharged at a constant current of 20 mA, the discharge could be performed for 9 minutes until the closed circuit voltage decreased to 0.9V. The initial discharge voltage is approximately 1.5V,
The average discharge voltage (closed circuit voltage) was about 1.2V. After this discharge, when the battery was charged at a constant current of 20 mA for 15 minutes and then discharged at a constant current of 20 mA, a discharge time of 9 minutes was obtained until the closed circuit voltage decreased to 0.9V.

Furthermore, when the battery was charged at a constant current of 10 mA for 15 minutes and then discharged using the same operation, the 10 mA constant current discharge could be performed for 12 minutes before the closed circuit voltage decreased to 0.9V. In addition, including the following other examples, there was almost no change in the charging and discharging characteristics of the batteries of the present invention whether they were charged or discharged in air or in an inert gas such as N2.

Example 2. A disk-shaped glass fiber filter paper with a diameter of 13 mm impregnated with 100 μl of a 2M ZnSO4 aqueous solution is placed on a zinc plate with a thickness of 0.4 mm. On the other hand, 40 mg of manganese dioxide (TAM, manufactured by Mitsui Kinzoku Mining Co., Ltd.) and 10 mg of Ketchen Black are mixed and ground in an agate mortar to prepare a powdery mixture. This powdery mixture is placed on the disk-shaped glass fiber filter paper so as to be approximately evenly distributed. Further, a platinum plate as a current collector was placed on top of this and the whole was fixed to produce the battery shown in FIG. 1. This battery was placed in a nitrogen gas atmosphere and shielded to prevent water evaporation.
After about 3 hours, the closed circuit voltage reached 0.9V.
Stop discharging when the temperature reaches the limit. Next, connect this battery to 2m
If the battery is charged for 240 minutes at a constant current of A, and then discharged at a constant current of 2 mA after a 10 minute dead period, the closed circuit voltage will be 0.
It is possible to discharge for 170 minutes until the voltage reaches 9V.
Furthermore, it was possible to perform discharge for 190 minutes until the closed circuit voltage reached 0.5V. When calculated based on the discharge time until the voltage reaches 0.9V, the current efficiency of this charging and discharging is 71%, and the utilization rate of manganese dioxide calculated from the discharge time is 46% based on one-electron discharge. be. The above charge/discharge cycle could be repeated, and there was almost no change in the discharge time even in the 14th charge/discharge cycle.

Example 3. 40mg manganese dioxide (Mitsui Metal Mining TAM), 4
0 mg of nylon powder (nylon powder for sintering supplied by Spacey Chemical Co., Ltd.) and 20 mg of Ketsuchen Black were mixed and ground in an agate mortar.
Molding under a pressure of 0 kg/cm2. Example 1. In the same manner as above, the electrode material for the positive electrode having a disk shape with a diameter of 13 mm, which was molded in this way, and a 2M ZnSO4 aqueous solution (100 μl) were added.
The battery shown in FIG. 1 was prepared by assembling a disk-shaped glass fiber filter paper impregnated with 13 mm in diameter, a zinc plate, and a platinum plate (current collector). When this battery is placed under nitrogen gas and shielded to prevent water evaporation and discharged at a constant current of 2 mA, 15
After 5 minutes, the closed circuit voltage became 0.9V. After this discharge, the battery was charged at a constant current of 2 mA for 60 minutes and then
When discharged at a constant current of mA, it was possible to discharge for 56 minutes until the closed circuit voltage decreased to 0.9V. The final voltage during charging is approximately 1.6V, and the initial closed circuit voltage during discharging is approximately 1.5V.
The charging/discharging current efficiency was 93% and the energy efficiency was about 65%.

In addition, similar charging and discharging was performed on a battery prepared in the same manner as above except that another polymer compound was used in place of nylon, and the results shown in the table below regarding the charging time and the corresponding discharging time were obtained.

Table 1. In both the charging and discharging times of the battery, the battery was charged and discharged at a constant current of 2 mA, and the battery was discharged until the closed circuit voltage reached 0.9 V. The polymer compounds shown in the table were purchased from Polysciences.

Also, instead of the polymer compound, use the substances in the table below (all in powder form)
A battery similar to the above battery of this example was manufactured by the same method as the above battery manufacturing method of this example except that
The charging and discharging times shown in the table below were obtained by performing charging and discharging in the same manner as the above-mentioned charging and discharging in this example.

Table 2. In addition to the charging and discharging times of batteries, in addition to those shown in Table 1, ion exchange resins such as naphion (trademark of DuPont), polyacrylamide, nylon-6, polyvinyl chloride, polyurethane, and amberlite, and high-density resins such as melamine resin, etc. Charging and discharging were also possible using molecular compounds. In the case of polyurethane, even when using a bulky material such as urethane foam, a discharge time of 155 minutes was obtained compared to a charging time of 177 minutes. Furthermore, regarding the battery No. 6 in Table 1, even if the solvent for dissolving ZnSO4 was changed from water to a mixture of water and methyl alcohol (volume ratio of water and methyl alcohol = 9:1), the results shown in No. 6 in Table 1 remained the same. Almost the same charging and discharging times were obtained, and no decrease in the discharging time was observed even after charging and discharging this battery three times in a row. Similarly, charging and discharging could be performed using a mixture of water and acetone as a solvent for dissolving ZnSO4 (volume ratio of water and acetone = 20:1).

Throughout this example, the amount of manganese dioxide (TAM manufactured by Mitsui Kinzoku Mining Co., Ltd.) used was 40 mg, the amount of substances such as polymer compounds added was 40 mg, and the amount of Kettian Black added was 40 mg. It was 20 mg. Both charging and discharging were performed at a constant current of 2 mA.

Example 4. Example 3. Among the batteries prepared in the above, the substances coexisting with manganese dioxide during the preparation of the positive electrode material were polymer compounds corresponding to numbers 1, 2, 3, 4, 5, and 6 among the polymer compounds shown in Table 1. In one case, a charge/discharge cycle was performed in which the battery was charged at a constant current of 2 mA for the charging time shown in Table 1, and then discharged at a constant current of 2 mA until the closed circuit voltage dropped to 0.9V. As a result, the discharge time during the third charge/discharge cycle was almost the same as the discharge time shown in Table 1.

In addition, for the batteries No. 4 and 6 in Table 1 and No. 5 in Table 2 (both described in Example 3), the batteries were similarly tested at a constant current of 2 mA for the times indicated in the corresponding locations in each table ( A charge/discharge cycle was performed in which the battery was charged for a period of time (charging time) and then discharged at a constant current of 2 mA until the closed circuit voltage dropped to 0.9 V. As a result, in all cases, the discharge time was almost the same as the discharge time shown in the corresponding section in each table even during the 10th charge/discharge cycle.

Also, Example 3. When the material coexisting with manganese dioxide in the preparation of the positive electrode material in the battery prepared was nylon powder for sintering, charging was performed for 60 minutes at a constant current of 2 mA, and then the closed circuit voltage became 0.9 V. up to 2m
A charge/discharge cycle of discharging at a constant current of A was continuously repeated. As a result, the discharge time (56 minutes) remained almost unchanged even after 140 charge/discharge cycles, and almost no deterioration in the performance of this battery as a secondary battery was observed even after 140 charge/discharge cycles. I found out that there isn't. This discharge time corresponds to approximately 93% current efficiency, and the closed circuit voltage at the final charge during repeated charge/discharge cycles (the closed circuit voltage at the end of charging) is 1.6 to 1. It was .7V. Further, the initial closed circuit voltage during discharge was 1.4 to 1.5V. The average value of the closed circuit voltage during discharge is approximately 1.15V,
The open circuit voltage is 1.4 when the discharge is nearing the end.
It showed a value of 1.5V to 1.5V.

Example 5. Example 3. In the same manner as above, 40 mg of manganese dioxide (TAM, Mitsui Kinzoku Mining Co., Ltd.) and 40 mg of nylon powder (
A positive electrode material consisting of sintering nylon powder (supplied by Spacey Chemical Co., Ltd.) and 20 mg of Ketchen Black was molded into a disk shape. This positive electrode material, 100
Disc-shaped glass fiber filter paper 13 mm in diameter containing μl of water, ion exchange membrane or dialysis membrane, 100 μl of 2MZnSO
4 Disc-shaped glass fiber filter paper containing an aqueous solution with a diameter of 13 mm and a zinc plate are stacked in this order, and a platinum plate as a current collector is closely attached to the positive electrode material, and the whole is fixed with metal fittings etc. to form the structure shown in Figure 2. A battery was created. Regarding this battery, Example 4. Similarly, a charge/discharge cycle was repeated in which the battery was charged at a constant current of 2 mA for 60 minutes and then discharged at a constant current of 2 mA until the closed circuit voltage decreased to 0.9 V. As a result, AM manufactured by Asahi Glass Co., Ltd. was used as an ion exchange membrane.
When V, ASV or DMV anion exchange membranes are used, the current efficiency is 87% to 92% in all cases.
It was possible to perform charging and discharging zero or more times. Charging and discharging was also possible when CMV manufactured by Asahi Glass Co., Ltd. was used as the ion exchange membrane. Furthermore, when cellophane for ion dialysis is used as a dialysis membrane, the above charging and discharging can be performed 100 times (10 times) at a current efficiency of 90%.
0 cycles) or more.

Example 6. 400 mg nylon-6 (Polysciences
Dissolve 10cm3 of formic acid in 10cm3 of formic acid, stir vigorously and add 80mg of Ketsuchen Black and 40cm3
0mg powdered manganese dioxide (HH- manufactured by Toyo Soda Co., Ltd.)
P type) is added. Of the dispersion thus obtained, 0.
After applying 10 ml almost uniformly onto a 1 cm x 1 cm carbon fiber cloth (KGF-100, manufactured by Kureha Chemical Industry Co., Ltd.) as a current collector, the formic acid is removed by a drying method. The battery shown in Fig. 1 was fabricated using the positive electrode material formed on the carbon fiber cloth as the current collector, glass fiber filter paper impregnated with 100 μl of a 2M ZnSO4 aqueous solution, and a zinc plate. . After connecting the positive and negative poles of this battery with a conductor and discharging it sufficiently until the closed circuit voltage becomes 0.5V or less,
The battery was charged at a constant current of A for 15 minutes. After this, when a constant current discharge of 2 mA is performed, the closed circuit voltage at the initial stage of discharge is 2.0
The closed circuit voltage was 1.1 V after 10 minutes of discharge, and about 0.5 V after 12 minutes of discharge. About this battery,
Such charging and discharging (constant current charging at 2 mA for 15 minutes, followed by constant current discharging at 2 mA until the closed circuit voltage reached 0.5 V) was repeated. As a result, 7
The same discharge behavior as above was also exhibited in the second charge/discharge cycle. Also, regarding this battery, the final voltage (
Set the voltage that stops charging when it reaches that voltage to 2.2V, and the final voltage during discharging (the voltage that stops discharging when the closed circuit voltage drops to that voltage) to 0.9V, and charge with a constant current of 2mA. A discharge was caused. As a result, the charging time and discharging time at the 10th charge/discharge cycle were 13 minutes and 9 minutes, respectively.
minutes, and the charging time at the 100th charge/discharge cycle,
The discharge time was 10 minutes and 8 minutes, respectively.

Furthermore, in the same manner as the above method of this example, except that another polymer compound was used instead of nylon-6 and a solvent that dissolved the polymer compound was used instead of formic acid.
A positive electrode material containing manganese dioxide, the polymer compound, and Ketchen Black was formed on a carbon fiber cloth, and a battery similar to that using nylon-6 was produced using this material. When these batteries are charged and discharged at a constant current of 2 mA, 5 to 1 % of the polymer compound is 6,6-nylon, polyacrylonitrile, or polymethyl methacrylate for 15 minutes of charging time.
A discharge time of 2 minutes was obtained.

In addition, in the above example of this embodiment, HH-P type manganese dioxide manufactured by Toyo Soda Co., Ltd. is used, but instead of this manganese dioxide, TAD, TSV, or TAM manufactured by Mitsui Mining Mining Co., Ltd. is used. No matter which manganese dioxide was used, a battery was obtained that exhibited almost the same charging and discharging behavior as the battery described above. Furthermore, instead of 2M ZnSO4 aqueous solution, 0.1
A battery using nylon-6 was fabricated using a ZnSO4 aqueous solution of M in the same manner as described above. This battery also
During the charge/discharge cycles described above, it showed almost the same charge/discharge behavior as the battery described above, but the discharge time during the fifth charge/discharge cycle was approximately 15% longer than that of the battery using a 2M ZnSO4 aqueous solution. A slight decrease in performance was observed, such as the length becoming shorter.

Example 7. An aqueous MnSO4 solution was electrolyzed using platinum as an electrode, and manganese dioxide was electrolytically deposited on a platinum plate. This was layered with a glass fiber filter paper impregnated with a 2M ZnSO4 aqueous solution and a zinc plate to produce the battery shown in FIG. 1. Using this battery, charging and discharging could be performed in the same way as the batteries described in other Examples.

Example 8. Example 3. Regarding a battery manufactured using nylon powder (nylon powder for sintering) and a 2M ZnSO4 aqueous solution as the electrolyte, (NH4) was added to the electrolyte as an auxiliary electrolyte.
)2SO4 was added. The battery obtained in this case is also (N
H4)2S04 was not added to the battery, which exhibited almost the same charging and discharging behavior as the battery obtained using the electrolytic solution.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of the battery. 1. A current collector such as a platinum plate or carbon fiber cloth; 2. is the positive electrode material, 3. is a substance containing an electrolyte; 4. is a zinc plate, 5. indicates a lead wire. FIG. 2 also shows a diagram of the battery arrangement. 1. A current collector such as a platinum plate or carbon fiber cloth; 2. is the positive electrode material, 3. is a substance containing water or an electrolyte; 4. 5. is a separator such as an ion exchange membrane; is a substance containing an electrolyte, 6. is a zinc plate, 7. indicates a lead wire.

Claims (6)

[Claims] (1) A rechargeable battery using a positive electrode material made using manganese dioxide, a negative electrode made using zinc, and an electrolyte made using zinc sulfate. (2) The battery according to claim 1, which uses a positive electrode material produced in a state in which manganese dioxide coexists with a substance that can appropriately disperse manganese dioxide. (3) The battery according to claim 2, wherein the substance capable of appropriately dispersing manganese dioxide is a polymer compound. (4) A patent claim characterized in that the substance capable of appropriately dispersing manganese dioxide is a substance that does not have high electrochemical reactivity, such as glass, zeolite, alumina, and silica. A battery according to scope 2. (5) The battery according to any one of claims 1 to 4, wherein the solvent of the electrolytic solution is water or water containing alcohol. (6) The battery according to any one of claims 1 to 5, characterized in that an ion exchange membrane or a dialysis membrane is interposed as a separator between the positive electrode side and the negative electrode side.