JP4852875B2 - Alkaline battery - Google Patents

Description

  The present invention relates to zinc or zinc alloy powder used as a negative electrode active material of an alkaline battery, and particularly to improve the high-rate discharge characteristics of the battery by improving the state of the negative electrode active material powder.

Conventionally, a negative electrode of an alkaline battery uses a gelled negative electrode in which zinc or a zinc alloy powder is used as a negative electrode active material, and an alkaline electrolyte and a gelling agent are mixed therewith.
JP 2001-332249 A

However, the negative electrode active material powder generates Zn (OH) ₄ ²⁻ on the surface at the time of discharge, and its concentration may rapidly increase on the surface of the active material particles. It was precipitated as (OH) ₂ . And these products acted as resistance on the surface of the negative electrode active material, and the contact state between the particles deteriorated, and the characteristics of the battery discharge, particularly at the high rate discharge, were lowered.

  The present invention has been made to solve such problems, and it is an object of the present invention to improve the high rate discharge characteristics of an alkaline battery using an active material powder of zinc or a zinc alloy.

In order to solve the above-mentioned problems, the present invention provides a gelled negative electrode comprising a negative electrode mixture containing zinc or zinc alloy powder as an active material, an alkaline electrolyte and a gelling agent , and an alkaline battery comprising a positive electrode. , the active material powder is characterized in that is coupled with tin between the particles, the content of the tin is 1 to 20 wt% relative to the zinc or zinc alloy.

Moreover, it is preferable that the specific surface area between the particles of the active material powder is 0.01 to 10 m ² / g.

  Moreover, it is preferable that the weight ratio of the amount of the alkaline electrolyte to the active material powder is in the range of 0.1 to 2. Further, the negative electrode mixture preferably contains lithium hydroxide in a proportion of 0.15 to 0.9 wt%.

  The present invention relates to an alkaline battery including a negative electrode using a negative electrode mixture containing zinc or zinc alloy powder as an active material, an alkaline electrolyte, and a positive electrode. Therefore, it is possible to improve the conductivity between the active material powders and improve the high rate discharge characteristics of the battery.

In order to solve the above-mentioned problems, the present invention provides a gelled negative electrode comprising a negative electrode mixture containing zinc or zinc alloy powder as an active material, an alkaline electrolyte and a gelling agent , and an alkaline battery comprising a positive electrode. , the active material powder is characterized in that is coupled with tin between the particles, the content of the tin is 1 to 20 wt% relative to the zinc or zinc alloy.

Moreover, it is preferable that the specific surface area between the particles of the active material powder is 0.01 to 10 m ² / g.

  Moreover, it is preferable that the weight ratio of the amount of the alkaline electrolyte to the active material powder is in the range of 0.1 to 2. Further, the negative electrode mixture is preferably contained at a ratio of 0.15 to 0.9 wt% of lithium hydroxide.

With this configuration, even if Zn (OH) ₄ ²⁻ exists around the active material powder and an insulating coating of Zn (OH) ₂ or ZnO is generated on the active material surface, the active material particles are sintered between the active material particles. Or since it is couple | bonded with metals other than zinc, the electroconductivity between particle | grains is maintained and it does not cause electroconductivity fall.

The specific surface area of the active material powder is particularly preferably 0.01 to 10 m ² / g. When the specific surface area of the active material powder is made smaller than 0.01 m ² / g, the size of the active material particle itself is increased, the reactivity between the active material and the electrolytic solution is lowered, and the polarization tends to increase. . On the contrary, when the specific surface area is larger than 10 m ² / g, the reactivity between the active material and the electrolytic solution becomes too high, and the active material powder tends to corrode and the gas generation amount tends to increase.

The weight ratio of the alkaline electrolyte to the active material powder is preferably 0.1-2. When the ratio of the weight of the electrolytic solution to the weight of the active material powder is smaller than 0.1, the concentration of Zn (OH) ₄ ²⁻ around the powder rapidly rises, and ZnO and Zn (OH) ₂ are generated. As a result, the expansion of ZnO or Zn (OH) ₂ is excessively large, the bonds between the particles are broken, and the conductivity between the particles tends to decrease. Conversely, when this ratio is greater than 2, the proportion of the electrolyte in the negative electrode mixture increases, and as a result, the amount of the active material powder in the negative electrode mixture decreases and the battery capacity tends to decrease.

  Furthermore, when the negative electrode mixture contains lithium hydroxide at a ratio of 0.15 wt% to 0.9 wt%, corrosion of zinc or zinc alloy powder can be suppressed and hydrogen gas generation can be further prevented.

  In addition, the composition of the zinc alloy is effective in suppressing gas generation by using an alloy in which at least one of Al, Bi, In, and Ca having a large hydrogen overvoltage is contained in zinc.

  The configuration of the air battery will be described with reference to FIG. FIG. 1 is a partial cross-sectional view of an air battery, wherein 1 is a negative electrode case, 2 is a negative electrode made of zinc, 3 is a ring-shaped insulating gasket, 4 is a positive electrode, a separator for preventing a short circuit between the negative electrodes, and 5 is an air electrode. , 6 is a water repellent film for preventing oxygen supply to the air electrode 5 and leakage of electrolyte to the outside of the battery, 7 is an air diffusion paper for uniformly diffusing air, and 8 is a positive electrode case. An air diffusion chamber 9 for accommodating the air diffusion paper 7 is provided on the bottom surface. Reference numeral 10 denotes an air hole provided in the bottom surface of the positive electrode case 8, and 11 denotes a seal paper for sealing the air hole 10 when not in use to block air from entering and preventing deterioration of the battery due to self-discharge. The air electrode 5 is configured by pressing a catalyst 12 mainly composed of a metal oxide, graphite, activated carbon, and a fluorine-based binder to a net-like current collector 13.

The configuration of the alkaline battery will be described with reference to FIG. In FIG. 2, a positive electrode mixture 102, a separator 104, and a gelled negative electrode 103 formed in a short cylindrical pellet shape are accommodated in the battery case 101. Battery case 101
For example, a steel case whose inner surface is nickel-plated can be used. On the inner surface of the battery case 101, a plurality of positive electrode mixtures 102 are accommodated in close contact. A separator 104 is disposed further inside the positive electrode mixture 102, and a gelled negative electrode 103 is further filled therein. The positive electrode mixture 102 was produced as follows. First, manganese dioxide, graphite, and an electrolytic solution were mixed at a weight ratio of 90: 6: 1, and the resulting mixture was sufficiently stirred and then compression-molded into flakes. Next, the flaky positive electrode mixture is pulverized into a granular positive electrode mixture, the granular positive electrode mixture is classified by a sieve, and a 10-100 mesh granule is pressure-molded into a hollow cylindrical shape to form a pellet. Of the positive electrode mixture 102 was obtained. Here, the positive electrode may be a mixture of manganese dioxide and nickel oxyhydroxide. Next, the four positive electrode mixtures 102 were inserted into the battery case 101, and the positive electrode mixture 102 was remolded with a pressure jig and adhered to the inner wall of the battery case 101. A bottomed cylindrical separator 104 was placed in the center of the positive electrode mixture 102 placed in the battery case 101 as described above, and a predetermined amount of alkaline electrolyte was injected into the separator 104. After elapse of a predetermined time, a gelled negative electrode 103 containing an alkaline electrolyte, a gelling agent, and a zinc alloy powder was filled into the separator 104. As the gelled negative electrode 103, one containing 1 part by weight of sodium polyacrylate as a gelling agent, 33 parts by weight of aqueous potassium hydroxide, and 66 parts by weight of zinc alloy powder was used. The separator 104 was a non-woven fabric (thickness 220 μm) obtained by mixing polyvinyl alcohol fibers and rayon fibers at a weight ratio of 7:10. The separator used had a density of 0.30 g / cm ³ , and the fineness of the fibers constituting the separator was 0.3 denier. In addition, the ratio of a fiber is not restricted to this, You may add another fiber as a binder. Subsequently, the negative electrode current collector 106 was inserted into the center of the gelled negative electrode 103. The negative electrode current collector 106 is integrated with a gasket 105 and a bottom plate 107 that also serves as a negative electrode terminal. Then, the opening end portion of the battery case 101 was caulked to the peripheral edge portion of the bottom plate 107 via the end portion of the gasket 105, and the opening portion of the battery case 101 was sealed. Finally, the outer surface of the battery case 101 was covered with the exterior label 108 to obtain an alkaline dry battery.

  As an electrolytic solution, an alkaline electrolytic solution in which KOH is dissolved in water is used. The KOH concentration of the alkaline electrolyte is 30 wt% to 45 wt%. In the electrolytic solution, ZnO may be dissolved in order to suppress the self-discharge of zinc, and the dissolved amount includes the entire range until saturation for each alkali concentration. In addition, an organic anticorrosive may be dissolved in the electrolytic solution in order to suppress the generation of hydrogen gas. The organic anticorrosive is not particularly limited as long as it suppresses the generation of hydrogen, and examples thereof include fluoroalkylpolyoxyethylene (trade name: Surflon # S-161). Further, the electrolytic solution may be in a gelled state. The gelling agent may be anything as long as it gels with an alkaline electrolyte. For example, carboxymethylcellulose, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, sodium polyacrylate, chitosan gel, Or what changed polymerization reaction, a crosslinking degree, and molecular weight etc. based on them is mentioned.

<About measurement of specific surface area>
The specific surface area was measured using a nitrogen adsorption method and using an ASAP2010 apparatus manufactured by Micromeritex Corporation. The conditions are shown below.

Pre-drying (deaeration condition): 120 ° C in vacuum for 5 hours Adsorption gas: N ₂ (nitrogen)
<About production of negative electrode>
Zinc powder is obtained by classifying what was synthesized using the atomizing method. And as shown in Table 1, zinc powder is baked in the range of 350 to 500 degreeC in a reducing atmosphere, and the negative electrode of the state which couple | bonded the particles is produced.

In addition, when zinc powders are bonded together via Sn, the Sn amount is 1
It can be produced by mixing ˜20 wt% with zinc and firing in a reducing atmosphere in the range of 180 ° C. to 250 ° C. Table 1 shows the case where the firing temperature is 230 ° C.

  In addition, zinc can be used as an alloy containing 50 to 1000 ppm of at least one of Al, Bi, In, and Ca when synthesized by the atomization method from the viewpoint of gas generation. Sn and Pb are also effective as other additive elements.

<Battery test>
Each battery was placed in a constant temperature bath maintained at 20 ° C. and a relative humidity of 60%, and discharged at each current density to obtain a discharge capacity C2 (mAh). The theoretical capacity C1 (mAh) was calculated from the Zn weight of each battery. The ratio P (%) of the discharge capacity C2 to the theoretical capacity C1 was calculated based on Formula 1 to evaluate the high rate discharge characteristics of each battery. A battery having a larger value of P is a battery having better high rate discharge characteristics. The results are shown in Tables 2-6.

Example 1
Table 2 shows the measurement results of P (%) at the discharge currents of 55 mA / cm ² and 1 A of the air battery and the alkaline battery manufactured using the negative electrode materials B1 to B19 shown in Table 1.

  As a method for producing a negative electrode material, an aggregate of zinc powder or zinc alloy powder (including one that is pressed and formed into a pellet) is fired at a temperature of 350 ° C. to 500 ° C. in a reducing atmosphere. Produced. Depending on the firing temperature, some aggregates were unglazed and others were melted into plates.

In the air battery and the alkaline dry battery using the materials B2 to B6 or the materials B9 to B18 as the negative electrode material, the value of P (%) at the discharge current of 55 mA / cm ² and 1 A is higher than that of the unfired materials B1 and B8. Both were better than 70% compared to the case of using as a negative electrode material. However, the negative electrode materials (B7, B19) having a firing temperature of 500 ° C. have a plate shape of zinc, and air batteries and alkaline dry batteries using the zinc form as negative electrode materials have extremely low P values.

  Thus, it can be understood that the discharge rate characteristics are considerably improved and effective when the powder is made in an unglazed state, that is, when zinc or zinc alloy powders are bonded together.

  Further, when an alloy containing at least one of Al, Bi, In, and Ca was used for zinc used for the negative electrode, liquid leakage after discharge hardly occurred. This is considered to be because hydrogen gas generation is suppressed by alloying. In addition, Sn and Pb also have an additive effect.

  These addition amounts are effective if they are in the range of 50 ppm to 5000 ppm, and more effective if they are in the range of 50 ppm to 300 ppm.

(Example 2)
A discharge current of 60 mA / cm ² at the discharge current of an air battery and an alkaline battery produced using a negative electrode material obtained by firing a mixture of zinc powder or zinc alloy powder and tin powder as shown in C1 to C21 of Table 1 at 230 ° C. and The results of measuring the value of P (%) at 1.1 A are shown in Table 3.

  As a method for producing the negative electrode material, zinc powder or zinc alloy powder and Sn powder having a particle size less than or equal to that of zinc powder or zinc alloy powder are mixed in a mortar, and an aggregate (pressed and formed into a pellet shape) And was fired at 230 ° C. in a reducing atmosphere.

  The values of P of the air battery and the alkaline dry battery using the materials C3 to C6 or the materials C10 to C20 as the negative electrode material were better than those of C1, C2, C8, and C9 whose Sn content was less than 1 wt%. Further, C7 and C21 having a Sn content of more than 20 wt% had a plate shape of zinc, and the values of P of air batteries and alkaline batteries using these as negative electrode materials were low.

  As described above, if the zinc powder or the zinc alloy is in an unglazed state bonded via Sn, the discharge rate characteristics are considerably improved, which is effective.

  Further, when an alloy containing at least one of Al, Bi, In, and Ca was used for zinc used in the negative electrode, liquid leakage after discharge hardly occurred. This is considered to be caused by alloying to suppress generation of hydrogen gas. In addition, Sn and Pb also have an additive effect.

  These addition amounts are effective if they are in the range of 50 ppm to 5000 ppm, and more effective if they are in the range of 50 ppm to 300 ppm.

(Example 3)
Values of P (%) at discharge currents of 50 mA / cm ² and 950 mA of air batteries and alkaline batteries produced using zinc powders or zinc alloy powders having different specific surface areas as shown in A1 to A19 of Table 1 The results of measuring the discharge capacity (mAh) at a discharge current of 1 mA / cm ² and 50 mA are shown in Table 4. The value of P of the air battery and the alkaline dry battery using the materials A2 to A7 or the materials A9 to A19 as the negative electrode material was as good as 50% or more. Moreover, the discharge capacity (mAh) of the air battery and alkaline dry battery which used material A1-A6 or material A8-A18 as a negative electrode material was ensured 900 mAh or more and 2450 mAh or more, and was favorable.

Thus, it was found that when the specific surface area of zinc or zinc alloy is in the range of 0.01 to 10 m ² / g, the discharge rate characteristics are excellent and a high discharge capacity can be obtained. Moreover, if the specific surface area of zinc or a zinc alloy is in the range of 0.01 to ¹ m ² / g, the battery capacities (mAh) of air batteries and alkaline batteries are ensured to be 955 mAh or more and 2600 mAh or more, which is even better.

  Further, when an alloy containing at least one of Al, Bi, In, and Ca was used for zinc used for the negative electrode, almost no leakage occurred after discharge. This is considered to be caused by alloying to suppress generation of hydrogen gas. In addition, Sn and Pb also have an additive effect. The amount of addition to zinc is effective in the range of 50 ppm to 5000 ppm, and more effective in the range of 50 ppm to 300 ppm.

Example 4
In Table 5, air batteries and alkaline dry batteries having different electrolyte / zinc weight ratios were prepared with respect to the material B17 shown in Table 1, and P (%) at discharge currents of 65 mA / cm ² and 1.15 A, respectively. ) Value and the discharge capacity (mAh) at a discharge current of 1.1 mA / cm ² and 51 mA, and the results are shown.

When the weight ratio of electrolytic solution / zinc was in the range of 0.1 to 2, the values of P (%) of the air battery and the alkaline battery were as good as 70% or more and 80% or more, respectively. Moreover, the discharge capacity (mAh) at the time of 1.1 mA / cm < ² > and 51 mA at the discharge current of an air battery and an alkaline battery was 800 mAh or more and 2200 mAh or more, respectively, and was favorable.

  Thus, it was found that when the electrolyte / zinc weight ratio was 0.1 to 2, the discharge rate characteristics were excellent and a high discharge capacity was obtained. Furthermore, if the weight ratio of electrolyte / zinc is 0.5-2, the value of P (%) of the air battery is 80% or more, the discharge capacity is 900 mAh or more, and the P ( %) Is 80% or more and the discharge capacity is 2200 mAh or more, which is quite effective.

  Further, when an alloy powder or plate containing at least one of Al, Bi, In, and Ca was used for the zinc powder and plate used for the negative electrode, almost no leakage occurred after discharge. This is considered to be caused by alloying to suppress generation of hydrogen gas. In addition, Sn and Pb also have an additive effect.

  These addition amounts are effective if they are in the range of 50 ppm to 5000 ppm, and more effective if they are in the range of 50 ppm to 300 ppm.

(Example 5)
Using the material of B17 shown in Table 1, a battery in which an air battery and an alkaline battery with different amounts of lithium hydroxide added to the negative electrode mixture were produced was produced. Table 6 shows the values of P (%) at discharge currents of 67 mA / cm ² and 1.2 A for air batteries and alkaline batteries, and discharge capacities at discharge currents of 1.2 mA / cm ² and 52 mA ( The results of measuring mAh) are shown. When the amount of lithium hydroxide with respect to the negative electrode mixture is in the range of 0.15 to 0.9, the P (%) value of the air battery and the alkaline battery is both 90% or more, and the discharge capacity is 950 mAh, respectively. As described above, a high capacity of 2600 mAh or more was shown. Thus, it was found that when the amount of lithium hydroxide relative to the negative electrode mixture is in the range of 0.15 to 0.9, the discharge rate characteristics are excellent and a high discharge capacity can be obtained. Moreover, if the amount of lithium hydroxide with respect to the negative electrode mixture is in the range of 0.21 to 0.72, the values of P (%) of the air battery and the alkaline battery are 91% or more and 92% or more, respectively. In addition, it was found that the battery capacities (mAh) at the discharge currents of 1.2 mA / cm ² and 52 mA of the air battery and the alkaline dry battery were 970 mAh or more and 2650 mAh or more, respectively, which were even better.

  Further, when an alloy powder or plate containing at least one of Al, Bi, In, and Ca was used for the zinc powder and plate used for the negative electrode, almost no leakage occurred after discharge. This is considered to be caused by alloying to suppress generation of hydrogen gas. In addition, Sn and Pb also have an additive effect.

  These addition amounts are effective if they are in the range of 50 ppm to 5000 ppm, and more effective if they are in the range of 50 ppm to 300 ppm.

  The present invention is applied to an alkaline battery using zinc or a zinc alloy as a negative electrode active material.

Vertical section of the air battery of the present invention Longitudinal sectional view of the alkaline battery of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Negative electrode case 2 Negative electrode 3 Gasket 4 Separator 5 Air electrode 6 Water repellent film 7 Air diffusion paper 8 Positive electrode case 9 Air diffusion chamber 10 Air hole 11 Seal paper 101 Battery case 102 Positive electrode mixture 103 Gelled negative electrode 104 Separator 105 Gasket 106 Negative electrode Current collector 107 Bottom plate 108 Exterior label

Claims (4)

A mixture comprising a zinc or zinc alloy active material powder, a gelled negative electrode containing an alkaline electrolyte and a gelling agent , and a positive electrode, wherein the active material powder is bonded with tin between the particles ; Content is 1-20 wt% with respect to the said zinc or zinc alloy, The alkaline battery characterized by the above-mentioned . The alkaline battery according to claim 1, wherein the active material powder has a specific surface area of 0.01 to 10 m ² / g. The alkaline battery according to claim 1, wherein the weight ratio of the amount of the alkaline electrolyte to the active material powder is in the range of 0.1 to 2. The alkaline battery according to claim 1, wherein the negative electrode mixture contains lithium hydroxide in a proportion of 0.15 to 0.9 wt%.

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