JP2005135730A - Alkaline storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline storage battery having an electrode body composed of a positive electrode supporting a positive electrode activator at a positive electrode support body on which, a positive electrode current collector is mounted; a negative electrode supporting a negative electrode activator at a negative electrode support body on which, a negative electrode current collector is mounted; and a separator, capable of obtaining sufficient preservation property even after charge/discharge cycle. <P>SOLUTION: On an alkaline storage battery having an electrode body 10 composed of a positive electrode 11 supporting a positive electrode activator at a positive electrode support body 11a on which, a positive electrode current collector 14 is mounted; a negative electrode 12 supporting a negative electrode activator at a negative electrode support body 12a on which, a negative electrode current collector 15 is mounted; a part of a separator, which is at least a neighboring area of the positive electrode supporting body or the negative electrode supporting body, is sulfonated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an alkaline storage battery, and in particular, in an electrode body including a positive electrode in which a positive electrode active material is held on a positive electrode support, a negative electrode in which a negative electrode active material is held on a negative electrode support, and a separator. In the alkaline storage battery in which the positive electrode current collector is attached to the support and the negative electrode current collector is attached to the negative electrode support, sufficient storage characteristics can be obtained even after the charge / discharge cycle. It has characteristics.

  Conventionally, nickel / cadmium storage batteries, nickel / hydrogen storage batteries, and the like have been used as alkaline storage batteries.

  In recent years, such alkaline storage batteries have been used for electric tools, electric vehicles, and the like, and high output alkaline storage batteries excellent in charge / discharge characteristics at a high rate have been demanded.

  As such an alkaline storage battery, an electrode body wound up with a separator interposed between a positive electrode in which a positive electrode active material is held on a positive electrode support and a negative electrode in which a negative electrode active material is held on a negative electrode support. On the end faces, there have been proposed ones in which current collectors are attached to the positive electrode support and the negative electrode support, respectively, so as to enhance the current collection performance of the positive electrode and the negative electrode (for example, Patent Document 1 and Patent Document 2). reference.).

  However, when such an alkaline storage battery is repeatedly charged and discharged, self-discharge tends to occur gradually, and the storage characteristics of the alkaline storage battery are greatly deteriorated.

  Conventionally, in order to suppress self-discharge in an alkaline storage battery, it has been proposed to use a sulfonated olefin resin as a separator interposed between a positive electrode and a negative electrode (for example, Patent Documents). 3).

However, when the entire separator is made of sulfonated olefin resin in this way, the impregnation rate of the alkaline electrolyte into the separator becomes slow, and immediately after the alkaline electrolyte is injected, the alkaline storage battery is There is a problem in that it cannot be activated by charging / discharging, the productivity deteriorates, and the anode active material reacts with the alkaline electrolyte and deteriorates until the separator is impregnated with the alkaline electrolyte. It was.
JP-A-56-109456 JP 2001-351672 A Japanese Patent Application Laid-Open No. 64-57568

  The present invention provides an electrode body including a positive electrode in which a positive electrode active material is held on a positive electrode support, a negative electrode in which a negative electrode active material is held on a negative electrode support, and a separator, wherein the positive electrode current collector is disposed on the positive electrode support. In the case where the above-mentioned various problems in the alkaline storage battery in which the negative electrode current collector is attached to the negative electrode support is attached and the above alkaline storage battery is repeatedly charged and discharged. However, the self-discharge is suppressed so that sufficient storage characteristics can be obtained, and the alkaline storage battery is immediately charged and discharged and activated without decreasing the impregnation rate of the alkaline electrolyte into the separator. It is an object to make it possible.

  Here, a positive electrode active material mainly composed of nickel hydroxide is used for the positive electrode, while a negative electrode active material made of a hydrogen storage alloy is used for the negative electrode, a positive electrode in which the positive electrode active material is held on the positive electrode support, and a negative electrode support In the end face of the electrode body wound with a separator interposed between the negative electrode holding the negative electrode active material, an alkaline storage battery in which a current collector is attached to each of the positive electrode support and the negative electrode support is used. When charging / discharging was repeated, cobalt or the like contained in the negative electrode active material was deposited on the separator in the vicinity of each of the current collectors.

  And it is thought that the insulation of a separator falls in the part in which cobalt etc. deposited in this way, self-discharge arises by this, and the storage characteristic of an alkaline storage battery has fallen.

  In order to solve the above problems, the alkaline storage battery according to the present invention includes a positive electrode in which a positive electrode active material is held on a positive electrode support, a negative electrode in which a negative electrode active material is held on a negative electrode support, and a separator. In the alkaline storage battery in which the positive electrode current collector is attached to the positive electrode support and the negative electrode current collector is attached to the negative electrode support, the positive electrode current collector and the negative electrode current collector are provided. The separator portion in the vicinity of at least one of the above was sulfonated.

  In the alkaline storage battery according to claim 2 of the present invention, in order to solve the above problems, a positive electrode in which a positive electrode active material is held on a positive electrode support and a negative electrode in which a negative electrode active material is held on a negative electrode support. A positive electrode current collector having a planar shape is attached to the positive electrode support on one end face of the electrode body in which a separator is interposed between the electrode body and the electrode body. The separator in the vicinity of at least one of the positive electrode current collector and the negative electrode current collector in an alkaline storage battery in which a planar negative electrode current collector is attached to the negative electrode support at the end surface opposite to the above The end of this was sulfonated.

  Here, when the portion of the separator in the vicinity of at least one of the positive electrode current collector and the negative electrode current collector is sulfonated as described above, if the width of the portion to be sulfonated becomes too large, as described above, Immediately after the alkaline electrolyte was impregnated, the alkaline storage battery could not be charged and discharged to activate it, resulting in poor productivity, and the separator was charged with alkaline electrolyte. Since the negative electrode active material is deteriorated by reacting with the alkaline electrolyte before impregnation, the width of the end to be sulfonated in the separator is d, and the distance between the positive electrode current collector and the negative electrode current collector When L is L, it is preferable to satisfy the condition of d ≦ 0.2L.

  In the alkaline storage battery according to the present invention, as described above, since the separator portion in the vicinity of at least one of the positive electrode current collector and the negative electrode current collector is sulfonated, the alkaline storage battery is repeatedly charged and discharged. In this case, the element contained in the negative electrode active material is suppressed from being deposited on the separator part in the vicinity of the positive electrode current collector or the negative electrode current collector to prevent self-discharge, and even after the charge / discharge cycle Sufficient storage characteristics can be obtained.

  Further, in the alkaline storage battery according to the present invention, since the entire separator is not sulfonated, only the separator portion in the vicinity of at least one of the positive electrode current collector and the negative electrode current collector is sulfonated as described above. Suppressing the slowing down of the impregnation rate of the alkaline electrolyte into the separator, and immediately after injecting the alkaline electrolyte, the alkaline storage battery can be charged and discharged to activate the productivity of the alkaline storage battery. In addition, it is possible to prevent the negative electrode active material from reacting with the alkaline electrolyte and deteriorating before the separator is impregnated with the alkaline electrolyte.

  Hereinafter, an experiment using an alkaline storage battery will be conducted, and it will be clarified that sufficient storage characteristics can be obtained even after a charge / discharge cycle in the alkaline storage battery of the present invention.

In this experiment, as a negative electrode active material, the composition is MmNi _3.2 Co _1.0 Al _0.7 Mn _0.1 (where Mm is a misch metal having a weight ratio of La: Ce: Pr: Nd = 25: 50: 6: 19). )), Hydrogen storage alloy particles having an average particle size of about 50 μm were used.

  In producing the negative electrode, 100 parts by weight of the above hydrogen storage alloy particles are added with a polyethylene oxide as a binder at a ratio of 1.0 part by weight, and a small amount of water is added thereto to uniformly distribute them. A paste was prepared by mixing the paste and the paste, and the paste was uniformly applied to both surfaces of a negative electrode support made of nickel-plated punching metal, which was dried and rolled to produce a negative electrode.

  Further, in manufacturing the positive electrode, a nickel nitrate aqueous solution in which cobalt nitrate and zinc nitrate are added is impregnated by a chemical impregnation method on a positive electrode support made of a nickel sintered substrate having a porosity of 85%, and cobalt, zinc, Nickel hydroxide containing was held on the positive electrode support. Thereafter, this was immersed in a 3% by weight yttrium nitrate aqueous solution, and further immersed in a 25% by weight sodium hydroxide aqueous solution at 80 ° C., so that cobalt and zinc held on the positive electrode support were retained. A coating layer of yttrium hydroxide was formed on the surface of nickel hydroxide containing and a positive electrode was produced. In this positive electrode, the amount of yttrium hydroxide was about 3% by weight with respect to the total amount of nickel hydroxide containing cobalt and zinc and yttrium hydroxide.

  In addition, as the separator, two separators, a non-sulfonated polyolefin non-woven fabric and a polyolefin non-woven fabric non-sulphonated as a whole, were used, and the alkaline electrolyte was 30% by weight of hydroxide. Using a potassium aqueous solution, an alkaline storage battery having a cylindrical shape and a capacity of about 1000 mAh as shown in FIG. 1 was produced.

  Here, in producing the above alkaline storage battery, as shown in FIG. 2, a separator 13a made of a non-sulfonated polyolefin non-woven fabric is placed inside the positive electrode 11 and the entire non-woven polyolefin non-woven fabric. The separator 13b made of the above is disposed outside the positive electrode 11, and the two sheets are spirally wound so that the separators 13a and 13b are interposed between the positive electrode 11 and the negative electrode 12, thereby forming the electrode body 10. At one end face of the body 10, a positive electrode current collector 14 having a planar shape is attached to the positive electrode support 11 a in the positive electrode 11, and the negative electrode support in the negative electrode 12 is attached to the other end face of the electrode body 10. The negative electrode current collector 15 having a planar shape was attached to the body 12a.

  Then, the electrode body 10 thus attached with the positive electrode current collector 14 and the negative electrode current collector 15 is accommodated in the outer can 20, and the negative electrode current collector 15 is attached to the bottom surface inside the outer can 20. The alkaline electrolyte is poured into the outer can 20, the lead portion 14 a is extended from the positive electrode current collector 14, and the lead portion 14 a is attached to the bottom 31 of the sealing body 30. Insulating gasket 32 is attached to the periphery of 30, this sealing body 30 is disposed in the opening of the above-described outer can 20, and the opening edge of the outer can 20 is caulked to attach the sealing body 30 to the outer can 20. I made it. In the sealing body 30 described above, a spring 34 and a valve 35 are provided between the bottom 31 and the positive electrode external terminal 33, so that when the internal pressure of the battery rises abnormally, the gas inside the battery is discharged. Released to the atmosphere.

  In the alkaline storage battery produced in this experiment, the distance L between the positive electrode current collector 14 and the negative electrode current collector 15 was 40 mm.

  And after charging the alkaline storage battery at 100 mA for 16 hours under a temperature condition of 25 ° C., it was discharged to 1.0 V at 1000 mA, and this was regarded as one cycle, and charging and discharging for 5 cycles were repeated, The alkaline storage battery was activated.

  Here, the alkaline storage battery activated as described above was charged at 500 mA for 1.6 hours under a temperature condition of 25 ° C., and then discharged to 1.0 V at 500 mA to obtain a discharge capacity before storage. Qo was measured and charged again at 500 mA for 1.6 hours. The alkaline storage battery was left in a temperature atmosphere at 45 ° C. for 7 days, and then discharged to 1.0 V at 500 mA under a temperature condition of 25 ° C. The discharge capacity Qa after storage was measured, the capacity retention rate (%) after storage was determined by the following formula, and the results are shown in Table 1 below.

  Capacity maintenance rate (%) = (Qa / Qo) × 100

  In addition, the alkaline storage battery activated as described above was charged to 400 mAh at a charging current of 1000 mA and a charging depth of 40% under a temperature condition of 45 ° C., then charged at 200 Ah at 10 A and 200 mAh at 10 A. The battery was discharged, and charging / discharging at 10A was taken as one cycle, and charging / discharging was repeated. Here, in the above alkaline storage battery, the charging efficiency is lower than the discharging efficiency, and the charging depth decreases as the cycle increases. Therefore, the battery is discharged every 1000 cycles until the battery voltage becomes 1 V, and is charged again. After charging up to 400 mAh at a charging depth of 40% at a current of 1000 mA, a cycle of charging at 200 Ah at 10 A and discharging at 200 mAh at 10 A was repeated for a total of 10,000 cycles of charge / discharge.

  And also about the alkaline storage battery which performed the charging / discharging cycle in this way, similarly to the case of the above-mentioned activated alkaline storage battery before performing the charging / discharging cycle, the capacity retention rate was obtained, and the result is shown below. It showed in Table 1.

  As is clear from this result, in the alkaline storage battery after the charge / discharge cycle as described above was performed, the capacity retention rate was remarkably reduced, and the storage characteristics were very poor.

  And as a result of disassembling the alkaline storage battery before performing said charging / discharging cycle and the alkaline storage battery after performing said charging / discharging cycle, taking out each said separator 13a, 13b, and observing visually, respectively, In the separator 13b made of a sulfonated polyolefin nonwoven fabric, almost no precipitate was present before and after the charge / discharge cycle.

  On the other hand, in the separator 13a made of a non-sulfonated polyolefin nonwoven fabric, the presence of precipitates was confirmed both before and after the charge / discharge cycle. Although a small amount was present uniformly, a large amount of precipitates existed in the vicinity of the positive electrode current collector 14 and the negative electrode current collector 15 after the charge / discharge cycle.

  And about the separator 13a which consists of a non-sulfonated polyolefin nonwoven fabric before and after the charge / discharge cycle, a part A 3 mm away from the positive electrode current collector 14, a part B 3 mm away from the negative electrode current collector 15, and a positive electrode The amount of Co in the intermediate portion C 20 mm away from each of the current collector 14 and the negative electrode current collector 15 was measured by fluorescent X-ray measurement. The results are shown in Table 2 below.

  As is clear from this result, when the separators 13a before and after the cycle are compared, in the portion A 3 mm away from the positive electrode current collector 14 and the portion B 3 mm away from the negative electrode current collector 15, the positive electrode current collector 14 Compared with the intermediate portion C between the negative electrode current collector 15 and the negative electrode current collector 15, the increase in the amount of Co after the cycle was very large.

  Then, in the separator 13a after the above cycle, a short circuit occurs at both ends near the positive electrode current collector 14 and the negative electrode current collector 15 where a large amount of Co is thus deposited, and the capacity retention rate is significantly reduced as described above. It seems to have done.

  For this reason, in the separator interposed between the positive electrode and the negative electrode as in the alkaline storage battery according to the present invention, when the end portion close to at least one of the positive electrode current collector and the negative electrode current collector is sulfonated, the whole is sulfonated. As in the case of the separator 13b made of a polyolefin non-woven fabric, it is considered that Co and the like are prevented from precipitating at the end portions even after the charge / discharge cycle, and the storage characteristics after the charge / discharge cycle are improved.

  In addition, in the separator interposed between the positive electrode and the negative electrode as in the alkaline storage battery in the present invention, if only the end portion close to at least one of the positive electrode current collector and the negative electrode current collector is sulfonated, the whole is sulfonated. Compared to the separator 13b made of a nonwoven fabric made of polyolefin, the impregnation rate of the alkaline electrolyte into the separator is increased, and immediately after the alkaline electrolyte is injected, the alkaline storage battery is charged and discharged and activated. It is possible to prevent the negative electrode active material from reacting with the alkaline electrolyte and deteriorating before the separator is impregnated with the alkaline electrolyte.

It is a schematic explanatory drawing of the alkaline storage battery produced in the experiment of this invention. In the experiment of the present invention, a separator made of a non-sulfonated polyolefin non-woven fabric was placed inside the positive electrode, and a separator made of a non-sulphated polyolefin non-woven fabric was placed outside the positive electrode. FIG. 5 is a development view showing a state in which an electrode body is formed by winding in a spiral shape so that is interposed between a positive electrode and a negative electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrode body 11 Positive electrode 11a Positive electrode support body 12 Negative electrode 12a Negative electrode support body 13a Separator 13b which consists of the nonwoven fabric made from the polyolefin which is not sulfonated, Separator which consists of the nonwoven fabric made from the polyolefin which made the whole sulfonate 14 Positive electrode collector 15 Negative electrode Current collector L Distance between the positive electrode current collector and the negative electrode current collector

Claims (4)

  In an electrode body comprising a positive electrode in which a positive electrode active material is held on a positive electrode support, a negative electrode in which a negative electrode active material is held on a negative electrode support, and a separator, a positive electrode current collector is attached to the positive electrode support. In addition, in the alkaline storage battery in which the negative electrode current collector is attached to the negative electrode support, the separator portion in the vicinity of at least one of the positive electrode current collector and the negative electrode current collector is sulfonated. Alkaline storage battery.   One end face of the electrode body in which a positive electrode in which a positive electrode active material is held on a positive electrode support and a negative electrode in which a negative electrode active material is held on a negative electrode support are stacked In addition, a planar positive electrode current collector is attached to the positive electrode support, and a negative electrode current collector is attached to the negative electrode support on the opposite end surface of the electrode body. An alkaline storage battery, wherein an end portion of the separator in the vicinity of at least one of the positive electrode current collector and the negative electrode current collector is sulfonated.   3. The alkaline storage battery according to claim 2, wherein d ≦ 0.2L, where d is a width of an end portion to be sulfonated in the separator, and L is a distance between the positive electrode current collector and the negative electrode current collector. An alkaline storage battery characterized by satisfying the following conditions.   The alkaline storage battery according to any one of claims 1 to 3, wherein a positive electrode active material mainly composed of nickel hydroxide is used for the positive electrode, and a negative electrode active material made of a hydrogen storage alloy for the negative electrode. An alkaline storage battery characterized by using.

Images