Production method of active material for positive electrode of alkaline secondary battery, positive electrode using the active material and production method of alkaline secondary battery using the positive electrode

The present invention is to provide a production method of an active material for an alkaline secondary battery comprising: a step of mixing particles comprising particles mainly containing nickel hydroxide and particles of a metal cobalt or a cobalt compound in a mixer with a sealed structure comprising a heating means in the presence of oxygen and an alkaline aqueous solution while heating. An active material produced by the method allows a high utilization. And a battery assembled with a positive electrode using the active material has an excellent high ratio discharge characteristic, and hardly causes the capacity decline even at the time of recharging after leaving in the over discharge state for a long time.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a production method of an active material
 for a positive electrode of an alkaline secondary battery, a positive
 electrode using the produced active material, and a production method of
 an alkaline secondary battery using the positive electrode, more
 specifically to a production method of an active material for a positive
 electrode having high utilization as an active material, unsusceptible to
 deterioration even in a long term storage, a positive electrode using the
 active material, and a production method of an alkaline secondary battery
 having an excellent high ratio discharge characteristic and capable of
 restraining the decline of the discharge capacity even at the time of
 recharging after leaving for a long time in an over discharge state.
 2. Prior Art
 Typical examples of alkaline secondary batteries include a nickel-hydrogen
 secondary battery and a nickel-cadmium secondary battery. In these
 batteries, a nickel electrode mainly comprising nickel hydroxide as the
 positive electrode active material is assembled as the positive electrode.
 As the nickel electrode, two kinds, that is, a sintered type and a
 non-sintered type are known.
 Among them, a non-sintered type nickel electrode is produced as follows.
 A viscous paste mixture for positive electrode is prepared by kneading a
 nickel hydroxide powder which functions as an active material for a
 positive electrode and a binder such as carboxy methyl cellulose, methyl
 cellulose, sodium polyacrylate, and polytetrafluoroethylene with water.
 Then, the paste is filled or applied to a collector such as a
 three-dimensional substrate of a foamed nickel substrate, a net-like
 sintered substrate made of metal fibers or a non-woven fabric with the
 surface applied with nickel plating, and a two-dimensional substrate of a
 nickel punching sheet and an expand nickel, followed by a drying treatment
 and a press forming so that the above-mentioned paste mixture is filled
 and supported in the collector in the dry state.
 Since a non-sintered type nickel electrode produced by above mentioned
 method has a higher filling density of a nickel hydroxide (active
 material) compared with a sintered type, it is advantageous in that a
 battery with a high discharge capacity can be provided.
 With the above-mentioned nickel electrode as the positive electrode, an
 alkaline secondary battery is assembled as follows.
 A generating element is produced by placing a separator having the electric
 insulating property and the liquid maintaining property between the
 above-mentioned nickel electrode and a predetermined negative electrode.
 When the purposed alkaline secondary battery to be produced is a
 nickel-cadmium secondary battery, a negative electrode supporting a
 mixture for negative electrode having a cadmium compound such as a metal
 cadmium and a cadmium hydroxide as the negative electrode active material
 is used. When the purposed alkaline secondary battery to be produced is a
 nickel-hydrogen secondary battery, a negative electrode supporting a
 mixture for negative electrode mainly comprising a hydrogen absorbing
 alloy is used. As a separator, a non-woven fabric of a polyamide fiber or
 a non-woven fabric of a polyolefin fiber such as a polyethylene fiber and
 a polypropylene fiber, applied with a hydrophilic treatment can be used
 commonly.
 The above-mentioned generating element is placed in a battery can with the
 bottom also serving as a negative terminal comprising a nickel plating
 steel plate, for example, and a predetermined amount of an alkaline
 electrolyte is filled therein. Examples of the alkaline electrolyte
 include, in general, an aqueous solution of sodium hydroxide, an aqueous
 solution of potassium hydroxide, an aqueous solution of lithium hydroxide,
 and an optional mixture thereof.
 Then, after placing a positive electrode terminal at the opening of the
 battery can, the entirety is sealed so as to provide a battery.
 The initial charging is conducted to the assembled battery so as to apply
 the activating treatment for the nickel hydroxide, which is the activate
 material, prior to the shipment. In general, the initial charging is
 conducted under the condition where quantity of electricity more than 100%
 of the theoretical capacity of the assembled nickel electrode can be
 charged.
 In the above-mentioned nickel electrode, it is important to improve the
 conductivity within the active material (nickel hydroxide), and between
 the active material and the collector for improving the utilization of the
 active material.
 In order to achieve the task, the following treatment has been adopted
 conventionally.
 In preparing a paste mixture for a positive electrode, a predetermined
 amount of particles of a metal cobalt, a cobalt compound such as cobalt
 hydroxide, cobalt trioxide, cobalt tetroxide, and cobalt monoxide, or a
 mixture thereof are added as a conducting material so as to produce a
 powdery material mixed with the nickel hydroxide particles by a
 predetermined ratio to be used as the active material.
 If a nickel electrode supporting the active material produced by above
 mentioned method is assembled in an alkaline secondary battery as the
 positive electrode, the metal cobalt or the cobalt compound contained in
 the above-mentioned powdery material is dissolved temporarily in the
 alkaline electrolysis solution as complex ions, and is distributed on the
 surface of the nickel hydroxide particles, which are the active material.
 At the time of the initial charging of the battery, the complex ions are
 oxidized earlier than the nickel hydroxide so as to be converted to an
 oxide of higher order such as oxycobalt hydroxide. It is precipitated
 among the nickel hydroxide particles, which are the active material, and
 between the active material layer and the collector so as to form a
 conductive matrix. Therefore, the collecting efficiency at the nickel
 electrode can be improved, and consequently, the utilization of the active
 material can be improved. In that case, with a larger number of contacting
 points between the above-mentioned conductive matrix and the nickel
 hydroxide particles, the utilization of the nickel hydroxide particles
 (active material) can further be improved.
 Moreover, a method of treating the powdery material produced as mentioned
 above with a heat alkaline aqueous solution is also known.
 Specifically, the above-mentioned powdery material is soaked in an alkaline
 aqueous solution so that the alkaline aqueous solution is applied or
 impregnated to the powdery material. Then, the entirety is filtrated so
 that the substance obtained by the filtration is heated at a predetermined
 temperature. According to the method, a part of the metal cobalt or the
 cobalt compound contained in the powdery material is dissolved in the heat
 alkaline aqueous solution as complex ions so that they homogeneously cover
 the surface of the particles mainly comprising the nickel hydroxide. Then,
 it is changed into an active material having factors of forming the
 above-mentioned conductive matrix.
 However, in this method of treating the above-mentioned powdery material
 with the heat alkaline aqueous solution, the cobalt complex ions
 temporarily dissolved in the heat alkaline aqueous solution may be
 precipitated again in the cooling process of the heat alkaline aqueous
 solution so as to form particle aggregates by bonding adjacent particles
 with each other. Therefore, since the obtained treated substance is an
 assembly of the above-mentioned particle aggregates, if paste mixture for
 a positive electrode is prepared with the treated substance, the
 distribution state of the nickel hydroxide particles, which are the
 positive electrode active material in the paste, becomes uneven, and thus
 it is problematic in that the effective use as the active material cannot
 be realized.
 As another method, for example, a method of using a powdery material
 prepared by introducing particle mainly comprising nickel hydroxide into
 an alkaline aqueous solution controlled to be in the range of pH 11 to 13
 and gradually adding, for example, an aqueous solution of cobalt sulfate
 so as to cover the surface of the above-mentioned particles with the
 formed cobalt compound like cobalt hydroxide for the use as the active
 material can be presented.
 According to the method, the surface of the nickel hydroxide particles can
 be covered with a small amount of a cobalt compound, however, a problem is
 involved in that the formation amount of the above-mentioned conductive
 matrix is reduced accordingly.
 In either case, in order to improve the utilization of the active material,
 it is advantageous to make a larger amount of the conductive matrix by
 increasing the amount of the metal cobalt or the cobalt compound in the
 above-mentioned powdery material.
 However, with a larger amount of the metal cobalt or the cobalt compound is
 included in the above-mentioned powdery material for improving the
 utilization of the active material, not only does the production cost of
 the nickel electrode increase, but also the relative ratio of the nickel
 hydroxide particles to serve as the positive electrode active material
 decreases, and thus it is disadvantageous for achieving a high capacity of
 the battery.
 Taking the above-mentioned into the account, an active material capable of
 performing the effects even with a minimum amount of the metal cobalt or
 the cobalt compound is preferable as the active material.
 In the case of a battery where a nickel electrode with a large amount of a
 metal cobalt or a cobalt compound is contained, the cobalt compound enters
 into the crystal structure of the nickel hydroxide particles under the
 over discharge state, and thus it is problematic in that the
 above-mentioned effects inherent to the cobalt compound, that is, the
 formation of the conductive matrix cannot proceed so as to disturb the
 improvement of the utilization of the active material.
 Recently, with various kinds of electronic appliances provided in a
 portable form, a nickel-hydrogen secondary battery or a nickel-cadmium
 secondary battery to be used as the driving power source is strongly
 required not to cause the decline of the capacity even after leaving a
 long time, to show a high ratio discharge characteristic from the initial
 stage, and to show an excellent discharge characteristic even in a low
 temperature environment, in addition to have a high capacity.
 In this case, in order to improve the high ratio discharge characteristic,
 it is known that a large amount of a metal cobalt or a cobalt compound in
 a nickel electrode, which is the positive electrode, is effective for
 improving the high ratio discharge characteristic.
 However, these methods run counter to the above-mentioned achievement of
 the high capacity of the battery, and thus they are not a method for
 improving the large current discharge characteristic without sacrificing a
 high capacity.
 On the other hand, the official gazettes of Japanese Patent Publication
 Laid-Open No. 8-195218 and 8-236145 disclose a method of conducting the
 initial charging in a high temperature until the metal cobalt or the
 cobalt compound included in the nickel electrode is oxidized completely
 into the oxycobalt hydroxide.
 According to the method, since the metal cobalt or the cobalt compound
 included in the nickel electrode can contribute to the formation of the
 conductive matrix without loss, a high capacity of the battery can be
 realized with a small amount of the metal cobalt or the cobalt compound.
 Besides, since the formed conductive matrix is firmer than the conductive
 matrix formed at the time of the initial charging in a room temperature,
 an effect of hardly causing the decline of the capacity even after leaving
 can be achieved.
 However, a problem is involved in that a high temperature atmosphere is
 required as the initial charging environment, and further, a longer
 initial charging time is needed so that the production cost as a whole is
 increased.
 Furthermore, the official gazette of Japanese Patent Publication Laid-Open
 No. 9-73900 discloses a method of precipitating cobalt hydroxide on the
 surface of nickel hydroxide particles, fluidizing or dispersing the same
 in an open device of a hot air convection method, spraying an alkaline
 aqueous solution thereto and agitating the same in a hot air flow such as
 hot air so as to convert the above-mentioned cobalt hydroxide into an
 oxide of higher order.
 Since an oxide of higher order of the cobalt is already formed on the
 surface of the nickel hydroxide particles produced by the method, itself
 is an active material with an improved utilization. A battery with the
 nickel hydroxide particles assembled as the positive electrode active
 material has the above-mentioned conductive matrix formed already at the
 time of completing the assembly.
 However, the method disclosed in the official gazette of Japanese Patent
 Publication Laid-Open No. 9-73900 has the following problems.
 The first problem is that the particles prepared by making the cobalt
 compound precipitate on the surface of the nickel hydroxide particles
 should be used as the starting material. In order to make the cobalt
 compound precipitate, as disclosed in the embodiments of the
 above-mentioned prior art, complicated procedure is required in terms of
 the concentration of the chemicals to be used the pH adjustment of the
 reaction field, control of the reaction time, and the like, and thus the
 conditions requiring a higher cost are needed so that it is problematic
 industrially.
 Moreover, since the heat treatment is conducted in a hot air convection
 method, the heat efficiency is poor, and thus it is another factor to
 raise the production cost. Besides, since an open system is required as
 the field for converting cobalt hydroxide into an oxide of higher order in
 a hot air convention method, a problem is involved in that an alkaline
 aqueous solution can easily be evaporated. With the evaporation of the
 alkaline aqueous solution, the amount of the cobalt compound precipitated
 on the surface of the nickel hydroxide particles, dissolved in the
 alkaline aqueous solution is reduced, and thus it disturbs the
 re-precipitation of the dissolved cobalt compound as an oxide of higher
 order.
 As an actual problem, in a battery assembled with a nickel electrode
 provided using an active material produced in the method, the utilization
 of the active material is low, and furthermore, a problem of decline of
 recovering the capacity after the storage in a high temperature
 environment or after a long term storage is caused.
 Moreover, in order to improve the heat efficiency at the time of reaction
 in the above-mentioned method, the flow amount of the hot air can be
 increased, but such a measure cannot be adopted since it will promote
 evaporation of the alkaline aqueous solution.
 As heretofore mentioned, in the above-mentioned prior arts, although nickel
 hydroxide particles having a factor of a conductive matrix for improving
 the utilization of the active material when used in a nickel electrode
 already formed can be produced, the above-mentioned various problems are
 involved.
 OBJECTS AND SUMMARY OF THE INVENTION
 An object of the present invention is to provide a production method of an
 active material for a positive electrode with a high utilization, without
 the risk of causing deterioration even after a long term storage.
 Another object of the present invention is to provide a production method
 of an active material for a positive electrode capable of reducing the
 content ratio of the metal cobalt or the cobalt compound to be used in the
 production of the active material containing the metal cobalt or the
 cobalt compound to the minimum level, and capable of forming an oxide of
 higher order of the cobalt on the surface of the nickel hydroxide
 particles at a low cost even if the nickel hydroxide particles and the
 particles of the cobalt compounds are used independently, unlike the
 above-mentioned prior art disclosed in the official gazette of Japanese
 Patent Publication Laid-Open No. 9-73900.
 Still another object of the present invention is to provide a positive
 electrode using the above-mentioned active material.
 Yet another object of the present invention is to provide a production
 method of an alkaline secondary battery having an excellent high ratio
 discharge characteristic, without the risk of declining the discharge
 capacity even at the time of recharging after leaving for a long time in
 the over discharge state.
 Still another object of the present invention is to provide a production
 method of an alkaline secondary battery capable of omitting the initial
 charging after the battery assembly, or capable of reducing the charging
 time if the initial charging is conducted.
 In order to achieve the above-mentioned objects, the present invention
 provides a production method of an active material for a positive
 electrode of an alkaline secondary battery comprising:
 a step of mixing particles comprising particles mainly containing nickel
 hydroxide and particles of a metal cobalt or a cobalt compound in a mixer
 with a sealed structure having a heating means in the presence of oxygen
 and an alkaline aqueous solution while heating.
 Moreover, the present invention provides a positive electrode having the
 mixture mainly containing the active material for positive electrode
 produced by the above-mentioned method supported on the collector.
 Furthermore, the present invention provides a production method of an
 alkaline secondary battery comprising:
 a step of pouring a generating element comprising the above-mentioned
 positive electrode, a separator and a negative electrode and accommodating
 the same in a battery can;
 a step of pouring an alkaline electrolysis solution into the battery can
 with a liquid ratio corresponding to 0.5 to 1.6 cm.sup.3 /Ah with respect
 to the theoretical capacity (unit: Ah) of the positive electrode, and
 sealing the battery can for assembling the battery precursor; and
 a step of conducting the initial charging to the battery precursor.

DETAILED DESCRIPTION OF THE INVENTION
 The production method of an active material for a positive electrode
 according to the present invention will be explained.
 In the present invention, an active material for a positive electrode is
 produced in a mixer having a heating means.
 An example of the mixer structure to be used is shown in FIG. 1.
 The mixer comprises a mixer main body 1 with the open upper part and a lid
 member 2 provided detachably to the upper part opening 1a thereof. A
 horizontally rotatable stirring blade 3 is provided at the bottom part 1b
 of the mixer main body 1. Furthermore, a vertically rotatable chopper
 blade 4 is provided on the inner wall 1c in the vicinity of the bottom
 part 1b. A part 1d of the mixer main body above the chopper blade 4 is a
 cylindrical member with a circular truncated conical shape as a whole.
 On the other hand, the lid member 2 having a hat-like shape as a whole is
 provided with a nozzle 5 for supplying an alkaline aqueous solution. The
 nozzle 5 may be provided in the mixer main body 1.
 Therefore, by putting the lid member 2 on the upper opening 1a of the mixer
 main body 1 so as to be fixed to the mixer main body, the mixer as a whole
 can have a sealed structure with the sealed space formed internally.
 The sealed structure in the present invention refers to the state with a
 substantially sealed space is formed internally. For example, the case
 mounted with a member for connecting with a device for supplying an
 alkaline aqueous solution such as nozzle 5 as illustrated is also referred
 to as the sealed structure.
 The mixer is provided with a heating means to be described later. By the
 operation of the heating means, the temperature of the subject to be mixed
 in the mixer can be controlled at a certain value.
 A heating means may be a heating-cooling jacket 6 surrounding at least the
 outer periphery of the mixer main body 1 as shown in FIG. 1, however, a
 device for irradiating a radiation beam to the particles later described
 in the mixer is further preferable. Or both can be used in combination.
 The radiation beam in the present invention includes a microwave in
 addition to a heat beam such as an infrared ray and a far infrared ray.
 Therefore, as the latter heating device, a device for irradiating an
 infrared ray or a far infrared ray and a magnetoron for generating a
 microwave can be presented. In particular, a magnetoron for generating a
 microwave with a 1,000 MHz to 100 GHz frequency can be used preferably.
 By using the mixer, an active material for a positive electrode of the
 present invention can be produced as follows, using the particles later
 described.
 The particles in the present invention refer to a mixture of particles
 mainly containing nickel hydroxide and particles of a metal cobalt or a
 cobalt compound, or an agglomerate of particles with the surface of
 particles mainly containing nickel hydroxide adhered with a metal cobalt
 or a cobalt compound as disclosed in the official gazette of Japanese
 Patent Publication Laid-Open No. 9-73900. The explanation hereinafter will
 be given for the former particles.
 A predetermined amount of nickel hydroxide particles and particles of a
 metal cobalt or a cobalt compound (hereinafter referred to as cobalt
 compound particles) is placed in the mixer main body 1. By closing the lid
 member 2, the sealed mixer structure is formed. The horizontal blade 3 is
 operated, and at the same time, the chopper blade 4 is operated.
 Since the ascending driving force and the centrifugal force are applied to
 the mixture of the introduced particles by the rotation of the horizontal
 blade 3, the mixture (the particles) repeats the movement of ascending
 along the inner wall of the mixer main body 1 while turning and dropping
 from the lid member 2 so as to agitate and evenly mix the mixture in the
 process. Even if an aggregate (lump) is formed in the ascending mixture,
 the aggregate can be pulverized by the vertical rotation of the chopper
 blade 4 provided on the inner wall 1c of the mixer main body, the size of
 the mixture obtained after agitation and mixing can be homogeneous.
 In the present invention, the heating means 6 is operated in the state
 where the inside of the mixer main body 1 is filled with an
 oxygen-including atmosphere such as atmosphere. And a heat treatment is
 applied for controlling the temperature of the agitated and mixed mixture
 at a predetermined temperature, and at the same time, an alkaline aqueous
 solution of a predetermined concentration is supplied from the nozzle 5
 provided in the lid member 2 so that the mixer with the sealed structure
 can operate in the above-mentioned embodiment.
 In the process, the nickel hydroxide particles and the cobalt compound
 particles can be mixed homogeneously, at the same time, the supplied
 alkaline aqueous solution is adhered on the surface of the mixture, the
 reaction field where the alkaline aqueous solution, and the cobalt
 compound particles and oxygen coexist is formed on the surface of the
 nickel hydroxide particles. As a result, the cobalt compound particles are
 converted to an oxide of higher order so as to cover the surface of the
 nickel hydroxide particles.
 As the cobalt compound particles, metal cobalt particles, cobalt hydroxide
 particles, cobalt trioxide particles, cobalt tetroxide particles, and
 cobalt monoxide particles can be used alone, or as a mixture of two or
 more.
 In this case, the amount of the cobalt compound particles in the mixed
 particles is preferably set in the range from 0.5 to 20% by weight. With
 less than 0.5% by weight, the above-mentioned formation of the conductive
 matrix at the time of the initial charging of the battery assembled with a
 nickel electrode for supporting the obtained active material is
 insufficient and thus the utilization of the active material cannot be
 improved. On the other hand, with more than 20% by weight, the relative
 ratio of the nickel hydroxide particles in the active material is reduced
 so that the discharge capacity of the battery is lowered.
 Examples of the alkaline aqueous solution to be used include an aqueous
 solution of a sodium hydroxide, an aqueous solution of potassium
 hydroxide, and a mixture thereof further including an aqueous solution of
 lithium hydroxide.
 It is preferable to set the concentration of the alkaline aqueous solution
 in the range from 1 to 14N. With a low concentration lower than 1N, the
 dissolution ability with respect to the cobalt compound particles
 contained in the mixture becomes low so that the formation of the
 above-mentioned conductive matrix cannot be formed sufficiently, and thus
 the utilization of the active material cannot be improved. On the other
 hand, with a high concentration higher than 14N, the viscosity of the
 alkaline aqueous solution becomes too high to sufficiently permeate into
 the inside of the particles and thus the cobalt compound particles cannot
 be dissolved sufficiently.
 The amount of the alkaline aqueous solution is preferably set at 5 to 20
 parts by weight with respect to 100 parts by weight of the mixed
 particles. With less than 5 parts by weight, the entirety of the cobalt
 compound particles contained in the mixed particles can hardly dissolved
 and thus the utilization of the obtained active material cannot be
 improved, and further, the capacity recovery ratio after storage of a
 battery produced therewith cannot be improved. With more than 20 parts by
 weight, the mixed particles are granulated. A preferable amount is from 10
 to 15parts by weight with respect to 100 parts by weight of the mixed
 particles.
 As the heating means 6 for heating the above-mentioned particles while
 agitating and mixing, a heating-cooling jacket provided outside the mixer
 main body 1 for indirectly heating the inside particles can be used.
 However, a device for directly irradiating a radiation beam to the inside
 particles such as an infrared ray, a far infrared ray, or a microwave is
 preferable. In particular, a magnetoron for irradiating a microwave is a
 preferable device. Or both can be used in combination.
 The microwave vibrates water molecules which exist surrounding each
 particle contained in the mixed particles by the irradiation thereof,
 allowing homogeneous heating of the mixed particles themselves. Moreover,
 it is considered that the irradiation of the microwave generates defects
 in the crystal structure of the nickel hydroxide particles by the
 introduced energy, or change the state of the micro pores so as to enlarge
 the surface activity of the nickel hydroxide particles after treatment.
 An example of a production device for heating the mixed particles with a
 magnetoron is shown in FIG. 2.
 In the device, a wave guide 7a is mounted on the upper part of the lid
 member 2 so that the microwave generated by the magnetoron 7 can be
 irradiated into the sealed space in the mixer through the wave guide 7a.
 The wave guide 7a may be provided on the mixer main body 1.
 This device is operated as follows. As mentioned above, predetermined
 particles are placed in the mixer main body 1, the lid member 2 is closed
 to have the sealed structure in the mixer. By driving the horizontal blade
 3 and the chopper blade 4, at the same time, opening the valve 5a, a
 predetermined alkaline aqueous solution is supplied from the nozzle 5 into
 the mixer from a storage container 8.
 By operating the magnetoron 7, a microwave of a predetermined frequency is
 irradiated from the wave guide 7a into the mixer so as to heat the mixed
 particles. The temperature is measured by a thermometer 9, with the signal
 fed back to the operating device of the magnetoron 7 for the output
 control so that the temperature of the mixed particles can be controlled.
 The heat treatment by the microwave can be conducted for about 20 minutes
 while agitating the alkaline aqueous solution and the mixed particles.
 Since the mixed particles are always agitated and are always heated
 homogeneously by the microwave in the process, the above-mentioned problem
 of the re-precipitation of the cobalt complex ions according to the cool
 down of the alkaline aqueous solution. As a result, the adhesion between
 the adjacent nickel hydroxide particles can be restrained, and thus
 particle aggregates cannot be generated in the obtained treated substance.
 It is preferable to set the heat treatment temperature in the range from 35
 to 160.degree. C. With a temperature lower than 35.degree. C., the
 dissolution amount of the metal cobalt or the cobalt compound contained in
 the mixed particles into the alkaline aqueous solution becomes small so
 that the formation of the above-mentioned conductive matrix becomes
 insufficient and thus the utilization of the active material cannot be
 improved. On the other hand, with a temperature higher than 160.degree.
 C., the structural change is caused in the nickel hydroxide particles
 themselves so that they are deteriorated as the active material,
 furthermore, the heat cost is to be raised. A preferable heat treatment
 temperature is from 80 to 120.degree. C.
 Moreover, it is preferable to operate the magnetoron for oscillating the
 microwave with the output power in the range from 0.5 to 12 kW with
 respect to 1 kg of the mixed particles in the mixer. With an output power
 lower than 0.5 kW, the energy introduced from the microwave into the mixed
 particles is too small for sufficiently heating the mixed particles
 homogeneously in the above-mentioned temperature range. On the other hand,
 with an output power higher than 12 kW, an sufficient effect cannot be
 obtained in terms of the characteristics.
 It is also possible to use a mixer provided with a heating-cooling jacket
 on the outside with hot water sent into the jacket for having the mixer
 itself in a high temperature state, and further to apply the heat
 treatment of the mixed particles with the above-mentioned microwave. The
 above-mentioned heat treatment may be conducted while sending a high
 concentration oxygen to the inside of the mixer.
 Since production of an active material for a positive electrode according
 to the present invention is conducted in a mixer with a sealed structure,
 unlike the case of production with an open system device as disclosed in
 the official gazette of Japanese Patent Publication Laid-Open No. 9-73900,
 loss of the water content in the alkaline aqueous solution supplied in the
 mixer can be prevented. Therefore, the dissolution amount of the cobalt
 compound particles can be increased so that an active material with a high
 utilization can be obtained.
 A positive electrode of the present invention will be explained.
 The positive electrode supports a mixture for a positive electrode mainly
 containing an active material produced by the above-mentioned method on a
 collector.
 The positive electrode can be provide as the case of a conventional
 non-sintered type nickel electrode. That is, a consistent paste for
 positive electrode is prepared by kneading an active material produced by
 the above-mentioned method, a binder such as carboxy methyl cellulose,
 methyl cellulose, sodium polyacrylate, and polytetrafluoroethylene, and
 water with a predetermined ratio.
 The paste is filled or applied to a collector such as a three-dimensional
 substrate of a foamed nickel substrate, a net-like sintered substrate made
 of metal fibers or a non-woven fabric with the surface applied with nickel
 plating, and a two-dimensional substrate of a nickel punching sheet or an
 expanded nickel.
 Then, the drying treatment is applied to the entirely, followed by a press
 forming and cutting so as to be shaped into a predetermined shape.
 The production method of an alkaline secondary battery according to the
 present invention will be explained.
 A generating element is provided by placing a separator between the
 above-mentioned positive electrode and a negative electrode, and the
 generating element is accommodated in a battery can.
 When the purposed alkaline secondary battery to be produced is a
 nickel-hydrogen secondary battery, a negative electrode supporting a
 mixture for a negative electrode mainly comprising hydrogen occluded alloy
 powders is used. When the purposed alkaline secondary battery to be
 produced is a nickel-cadmium secondary battery, a negative electrode
 having a cadmium compound such as a metal cadmium and a cadmium hydroxide
 as the active material is used.
 After pouring a predetermined alkaline electrolysis solution into the
 battery can, the battery can is sealed with an ordinary method so as to
 assemble a battery precursor.
 The amount of the alkaline electrolysis solution to be poured is defined as
 follows.
 That is, it is defined to be the pouring amount with a 0.5 to 1.6 cm.sup.3
 /Ah liquid ratio with respect to the theoretical capacity (unit: Ah) of
 the positive electrode in the assembled generating element.
 With a pouring amount with a more than 1.6 cm.sup.3 /Ah liquid ratio,
 realization of a high capacity of the battery is disturbed. With a smaller
 liquid ratio, it is advantageous in realizing a high capacity of the
 battery, however, with a less than 0.5 cm.sup.3 /Ah liquid ratio, the
 utilization of the positive electrode is declined so as to deteriorate the
 high ratio discharge characteristic of the battery or the discharge
 characteristic after leaving.
 A preferable pouring amount is an amount with the above-mentioned liquid
 ratio of 0.8 to 1.2 cm.sup.3 /Ah.
 Finally, the initial charging is conducted to the battery precursor
 obtained by the above-mentioned process.
 At the time of the initial charging, unlike the conventional one, the
 condition of supplying a quantity of electricity of 100% or more with
 respect to the theoretical capacity of the positive electrode need not be
 adopted. Rather, it is preferable to have the initial charging with a less
 than 100% quantity of electricity to be supplied with respect to the
 theoretical capacity of the positive electrode. The reason is as follows.
 The initial charging is conducted for activating the positive and negative
 electrodes. In particular, this is an indispensable treatment for the
 positive electrode containing a cobalt component for forming a conducting
 matrix of oxycobalt hydroxide by oxidizing the cobalt component and for
 oxidizing the nickel hydroxide so as to be converted into oxynickel
 hydroxide. Therefore, in the conventional case, a sufficient quantity of
 electricity more than the theoretical capacity of the positive electrode
 is needed to be supplied at the time of the initial charging, expecting
 the oxidization of the above-mentioned cobalt component. Moreover, in
 order to completely oxidize the cobalt component prior to the nickel
 hydroxide, it was regarded as preferable to conduct the initial charging
 at a low rate.
 However, for a positive electrode of the present invention, since the
 active material is provided in the state where the conductive matrix of
 the cobalt component is formed already partially or entirely on the
 positive electrode, formation of the conductive matrix by the initial
 charging as in the conventional case is not required. That is, since the
 active material produced according to the present invention is already
 activated to some extent before the initial charging, the quantity of
 electricity to be needed for the initial charging may be sufficient even
 when the quantity of electricity in the initial charging is less than 100%
 of the theoretical capacity of the positive electrode.
 Moreover, since the initial charging need not be conducted with a low
 current for oxidizing the cobalt component prior to the nickel hydroxide,
 the initial charging may be conducted sufficiently at a charging rate of
 0.5 C or more.
 EXAMPLES 1 TO 7, COMATIVE EXAMPLE 1
 With the device shown in FIG. 2, a predetermined amount of nickel hydroxide
 particles having a 10 .mu.m average particle size and cobalt hydroxide
 particles having a 1 .mu.m average particle size were placed in the mixer
 main body 1 of the mixer with a ratio shown in Table 1 (% by weight).
 Then, the sealed structure was formed by closing the lid member 2. The
 weight of the mixed particles was 1 kg.
 Then, while moving the agitating blade 3 and the chopper blade 4, an
 aqueous solution of sodium hydroxide of an 8N concentration was supplied
 from the nozzle 5 of the lid member 2 by an amount sufficient for wetting
 the mixture of the particles. While agitating the mixture, the magnetoron
 was operated at 4.0 kW for irradiating a microwave. The heating treatment
 was conducted for 20 minutes with the temperature of the mixture at about
 100.degree. C. so as to produce an active material.
 For the comparison, the mixture used in the production of the active
 material of the example 4 was soaked in an aqueous solution of sodium
 hydroxide with a 12N concentration. Then, the entirety was spread evenly
 on a filter paper, heated at 100.degree. C. for about 30 minutes, and
 pulverized with a pulverizer. This is referred to as the comparative
 example 1.
 TABLE 1
 Treatment
 Nickel Cobalt Microwave
 hydroxide hydroxide treatment Agitation
 particles particles yes yes
 (% by weight) (% by weight) no no
 Example 1 99.8 0.2 yes yes
 Example 2 99.5 0.5 yes yes
 Example 3 95 5 yes yes
 Example 4 90 10 yes yes
 Example 5 85 15 yes yes
 Example 6 80 20 yes yes
 Example 7 75 25 yes yes
 Comparative 90 10 no no
 example 1
 2. Production of a Positive Electrode
 Using the active materials, a nickel electrode was produced as follows.
 With respect to 100 parts by weight of each active material, 0.2 part by
 weight of carboxy methyl cellulose, 1.0 part by weight of a PTFE
 dispersion (specific gravity 1.5, solid component 60% by weight), and 35
 parts by weight of water were added and kneaded so as to prepare a paste
 for a positive electrode.
 The paste was filled into a nickel plating porous sheet having a 95%
 porosity and a 1.7 mm thickness, dried and rolled so as to have a nickel
 electrode.
 At the time, the filling amount of the active material was adjusted such
 that the theoretical capacity as the nickel electrode is 1200 mAh.
 On the other hand, a negative electrode was produced as follows.
 A commercially available mish metal, Ni, Co, Mn and Al were mixed with a
 molar ratio of 4.0:0.4:0.3:0.3. The mixture was melted in a high frequency
 melting furnace. The molten product was cooled down for producing an ingot
 of a hydrogen absorbing alloy with a composition: MmNi.sub.4.0 Co.sub.0.4
 Mn.sub.0.3 Al.sub.0.3 (Mm refers to the mish metal). It was pulverized and
 classified so as to have alloy powders with a 50 .mu.m or less particle
 size.
 With respect to 95 parts by weight of the alloy powders, 1.0 part by weight
 of carboxy methyl cellulose, 3.0 parts by weight of a PTFE dispersion
 (specific gravity 1.5, solid component 60% by weight), 1.0 part by weight
 of carbon black, and 50.0 parts by weight of water were added so as to
 prepare a paste for a negative electrode.
 The paste was applied on a punching nickel sheet with a 45% opening ratio,
 dried and rolled so as to obtain a hydrogen absorbing alloy electrode
 (negative electrode).
 3. Evaluation
 (1) The characteristics were evaluated for the active material of the
 example 4 and the active material of the comparative example 1 as follows.
 A polyolefin non-woven fabric applied with a hydrophilic treatment was
 provided between the nickel electrode using the active material and the
 above-mentioned hydrogen absorbing alloy electrode as the separator. By
 winding the same spirally, two kinds of electrode groups (generating
 elements) were produced. The electrode groups were accommodated in a
 battery can, respectively. By pouring an aqueous solution of potassium
 hydroxide of a 8.5N concentration as the electrolysis solution and placing
 a sealing plate to the battery can, two kinds of sealed type cylindrical
 nickel-hydrogen secondary batteries (AA size) were assembled. The capacity
 per unit weight of active material and the high ratio discharge
 characteristic were measured unit weight for these batteries by the
 below-mentioned specification.
 The amount of introducing the electrolysis solution in the batteries was
 set to be a value to satisfy a 1.0 cm.sup.3 /Ah liquid ratio with respect
 to the theoretical capacity of each nickel electrode.
 Measurement of the capacity per unit weight active material: Charging was
 conducted for each battery at 360 mA for 5 hours. Then, discharging was
 conducted at 240 mA until the discharge ending voltage became 1.0V. The
 discharge capacity at the time was measured. The value obtained by
 dividing the measured value by the entire weight of the supported mixture
 (positive electrode compound) was defined as the capacity per the unit
 weight active material (mAh/g).
 Measurement of the high ratio discharge characteristic: Charging was
 conducted for each battery at 360 mA for 5 hours. Then, discharging was
 conducted at 2,400 mA until the discharge ending voltage became 1.0V (2 C
 discharge). The discharge capacity at the time was measured.
 Furthermore, charging was conducted for 5 hours. Then, discharging was
 conducted at 3,600 mA until the discharge ending voltage became 1.0V (3 C
 discharge). The discharge capacity at the time was measured.
 Results of the above-mentioned are shown in Table 2 as a relative value
 based on the measurement results of the battery assembled with the active
 material of the comparative example 1 as 100.
 TABLE 2
 Capacity High ratio
 per unit discharge
 weight of characteristic
 active 2C 3C
 material Discharge Discharge
 Case of a battery using the active 106 237 388
 Material of the example 4
 Case of a battery using the active 100 100 100
 Material of the comparative example
 1
 As apparent from Table 2, the battery using the active material of the
 example 4 is excellent in terms of both capacity per unit weight of active
 material and high ratio discharge characteristic although it was started
 from the material the same as that of the active material of the
 comparative example 1. This is the explicit proof of showing the
 effectiveness of the treatment by homogeneously heating with a microwave
 while agitating in the production of the active material.
 The example was the case where particles were introduced by 1 kg. It was
 confirmed that the same characteristic can be obtained in the range of a
 0.5 to 3 kg introduction amount.
 (2) The utilization of the active materials of the examples 1 to 7 were
 measured by the following single electrode potential test.
 With a nickel electrode produced with the active material of each example,
 the above-mentioned hydrogen occluded alloy electrode, and an aqueous
 solution of potassium hydroxide of an 8N concentration of the electrolysis
 solution, an open system simple cell was assembled.
 Charging was conducted to the simple cell at 240 mA for 24 hours. Then,
 discharging was conducted at 240 mA until the discharge ending voltage
 became 0.8 V. The discharge capacity at the time was measured.
 The discharge capacity was divided by the theoretical capacity of the
 nickel electrode for calculating the percentage thereof.
 Results of the above-mentioned are shown in Table 3.
 TABLE 3
 Contain-
 ing
 Nickel amount of
 hydroxide cobalt Utilization
 particles hydroxide of Active
 (% by (% by material
 Kind of the nickel electrode weight) weight) (%)
 Case of a nickel electrode supporting 99.8 0.2 96
 the active material of the example 1
 Case of a nickel electrode supporting 99.5 0.5 103
 the active material of the example 2
 Case of a nickel electrode supporting 95 5 106
 the active material of the example 3
 Case of a nickel electrode supporting 90 10 107
 the active material of the example 4
 Case of a nickel electrode supporting 85 15 107
 the active material of the example 5
 Case of a nickel electrode supporting 80 20 104
 the active material of the example 6
 Case of a nickel electrode supporting 75 25 95
 the active materia1 of the example 7
 As apparent from Table 3, in producing an active material by the method of
 the present invention, it is preferable to have the mixed particles by 80
 to 99.5% by weight of nickel hydroxide particles and 0.5 to 20% by weight
 of cobalt hydroxide particles.
 EXAMPLES 8 TO 13
 In the production condition the same as the example 4 with the mixed
 particles used for producing the active material of the example 4, except
 that the concentration of the aqueous solution of sodium hydroxide to be
 added was changed, various kinds of active materials were produced, and
 the utilization thereof was measured. Results thereof are shown in Table
 4.
 TABLE 4
 Concentration
 of an aqueous
 Mixed particles for solution of Utilization
 producing the active sodium of the active
 material hydroxide (N) material (%)
 Example 8 The same as the example 4 0.5 98
 Example 9 The same as the example 4 1 104
 Example 10 The same as the example 4 4 106
 Example 11 The same as the example 4 12 108
 Example 12 The same as the example 4 14 105
 Example 13 The same as the example 4 16 97
 As apparent from Table 4, in producing an active material in the present
 invention, it is preferable to use an aqueous solution of sodium hydroxide
 of a 1 to 14N concentration.
 EXAMPLES 14 TO 19
 In the production condition the same as the example 4 with the mixed
 particles used for producing the active material of the example 4, except
 that the heat treatment temperature was changed, various kinds of active
 materials were produced, and the utilization thereof was measured. Results
 thereof are shown in Table 5.
 TABLE 5
 Heat Utilization
 Mixed particles for treatment of the
 producing the active temperature active
 material (.degree. C.) material (%)
 Example 14 THE same as the example 4 30 98
 Example 15 The same as the example 4 35 103
 Example 16 The same as the example 4 70 105
 Example 17 The same as the example 4 130 107
 Example 18 The same as the example 4 160 105
 Example 19 The same as the example 4 190 94
 As apparent from Table 5, in producing an active material in the present
 invention, it is preferable to set the heat treatment temperature at 35 to
 160.degree. C.
 EXAMPLES 20 TO 25
 In the production condition the same as the example 4 with 1 kg of the
 mixed particles used for producing the active material of the example 4,
 except that the output power of the magnetoron was changed, various kinds
 of active materials were produced, and the utilization thereof was
 measured. Results thereof are shown in Table 6.
 TABLE 6
 Output power
 Mixed particles for of the Utilization of
 producing the active magnetron the active
 material (kW) material (%)
 Example 20 The same as the example 4 0.3 98
 Example 21 The same as the example 4 0.5 104
 Example 22 The same as the example 4 1.0 106
 Example 23 The same as the example 4 8.0 108
 Example 24 The same as the example 4 12.0 105
 Example 25 The same as the example 4 16.0 97
 As apparent from Table 6, in producing an active material in the present
 invention, it is preferable to set the output of the magnetoron at 0.5 to
 12.0 kW per 1 kg of the mixed particles.
 EXAMPLES 26 TO 37, COMATIVE EXAMPLES 2 TO 13
 1. Production of the Active Material
 To nickel hydroxide particles having a 10 .mu.m average particle size, 5%
 by weight of cobalt hydroxide particles having a 2.5 .mu.m average
 particle size were mixed for preparing 1 kg of mixed particles, which are
 the starting material of the active material. As the alkaline aqueous
 solution, an aqueous solution of sodium hydroxide of an 8N concentration
 was selected.
 The above-mentioned mixed particles were placed in the mixer with the
 sealed structure shown in FIG. 2. While agitating, an aqueous solution of
 sodium hydroxide was added thereto by an amount sufficient for wetting the
 mixed particles, and mixed. While agitating and kneading them, the
 magnetoron was operated at 4.0 kW for irradiating a microwave. A heat
 treatment was applied at about 100.degree. C. for 20 minutes so as to
 provide an active material of the present invention. This is referred to
 as an active material al (example 26).
 Moreover, by placing nickel hydroxide particles into an alkaline aqueous
 solution with the pH value adjusted in a weak base area, and gradually
 adding an aqueous solution of cobalt sulfate, a powdery material covered
 with the cobalt hydroxide was prepared. The adhesion amount of the cobalt
 hydroxide in the powdery material was the amount corresponding to 5% by
 weight.
 The same treatment was conducted to the powdery material as to the active
 material al so as to prepare an active material of the present invention.
 This is referred to as an active material a2 (example 27).
 For the comparison, the mixed particles as the starting material of the
 active material al were used as an active material. This is referred to as
 an active material a3 (comparative example 2).
 2. Production of the Electrode
 With the above-mentioned active materials al, a2, a3, the below-mentioned
 nickel electrode was produced.
 With respect to 100 parts by weight of each active material, 0.25 parts by
 weight of carboxy methyl cellulose, 0.25 parts by weight of sodium
 polyacrylate, 3,0 parts by weight of a PTFE dispersion (specific gravity
 1.5, solid component 60% by weight) and 35 parts by weight of water were
 added and kneaded so as to prepare a paste for a positive electrode.
 The paste was filled to a nickel plating porous sheet having a 95% porosity
 and a 1.7 mm thickness, dried and rolled so as to have a nickel electrode.
 The filling amount of the active material was adjusted such that the
 theoretical capacity as the nickel electrode became 4,000 mAh.
 Herein, the nickel electrode using the active material a1 is referred to as
 the nickel electrode b1 (example 28), the nickel electrode using the
 active material a2 is referred to as the nickel electrode b2 (example 29),
 and the nickel electrode using the active material a3 is referred to as
 the nickel electrode b3 (comparative example 3).
 On the other hand, a negative electrode was produced as follows.
 A commercially available La enriched mish metal, Ni, Co, Mn and Al were
 mixed with a molar ratio of 4.0:0.4:0.3:0.3. The mixture was melted in a
 high frequency melting furnace. The molten product was cooled down for
 producing an ingot of a hydrogen absorbing alloy with a composition:
 LmNi.sub.4.0 Co.sub.0.4 Mn.sub.0.3 Al.sub.0.3 (Lm refers to the La
 enriched mish metal). It was pulverized and classified so as to have alloy
 powders with a 50 .mu.m or less particle size.
 With respect to 100 parts by weight of the alloy powders, 0.125 parts by
 weight of carboxy methyl cellulose, 0.5 parts by weight of sodium
 polyacrylate, 1.5 parts by weight of a PTFE dispersion (specific gravity
 1.5, solid component 60% by weight), 1.0 part by weight of carbon black,
 and 50.0 parts by weight of water were added so as to prepare a paste for
 a negative electrode.
 The paste was applied on a punching nickel sheet with a 45% opening ratio,
 dried and rolled so as to obtain a hydrogen absorbing alloy electrode
 (negative electrode).
 3. Assembly of a Battery Precursor
 A hydrophilic polyolefin non-woven fabric was provided between the
 above-mentioned nickel electrodes b1, b2, b3 and the hydrogen absorbing
 alloy electrode as the separator to produce a generating element. It was
 inserted into a battery can.
 Then, an electrolysis solution mainly containing an aqueous solution of
 potassium hydroxide was poured into the battery can with the liquid ratio
 shown in Table 7. Then, the opening was sealed so as to assemble various
 precursors of cylindrical nickel-hydrogen secondary batteries of the 3/4A
 size with a 4,000 mA nominal capacity.
 4. Production of a Battery
 Batteries were produced by conducting the initial charging to these battery
 precursors with the condition shown in Table 7.
 5. Evaluation of the Obtained Batteries
 After charging the batteries by 0.1 C, discharging was conducted by 0. 2 C
 until the discharge ending voltage became 1.0V, and the discharge capacity
 (mAH) at the time was measured. By dividing the value by the initial
 capacity, the utilization (%) of the active material was calculated.
 Moreover, after leaving the battery under the discharge state in the
 atmosphere of 65.degree. C. for 1 month, 150% charging was conducted by
 0.1.degree. C. over 15 hours in the atmosphere of 25.degree. C. Then,
 discharging was conducted by 0.2 C until the discharge ending voltage
 became 1.0V. Furthermore, charging was conducted by 1 C for 1.5 hours, and
 discharging was conducted by IC until the discharge ending voltage became
 1.0V. This charging and discharging operation was repeated for 3 cycles.
 The discharge capacity at the time was measured. By dividing the value by
 the initial capacity, the capacity recovery ratio (%) was calculated.
 Results of the above-mentioned are shown in Table 7 comprehensively.

TABLE 7
 Battery
 characteristics
 Battery precursor
 Utilization
 nickel electrode Liquid Initial
 Discharge of the Capacity
 kind of active ratio charging
 capacity active recovery
 Kind kind material (cm.sup.3 /Ah) method
 (mAh) material (%) ratio (%)
 Comparative C1-1 b1 a1 0.3 100% 2960
 73 90
 example 4 (Example 28) (Example 26) charging
 Example 30 C1-2 b1 a1 0.5 by 0.5 C 3802
 94 98
 (Example 28) (Example 26) for 2 hours
 Example 31 C1-3 b1 a1 1.0 .fwdarw. 3995
 100 101
 (Example 28) (Example 26) discharging
 Example 32 C1-4 b1 a1 1.4 by 0.5 C 3900
 100 102
 (Example 28) (Example 26) to 1.0 V
 Example 33 C1-5 b1 a1 1.6 3603
 100 100
 (Example 28) (Example 26)
 Comparative C1-6 b1 a1 1.7 3355
 102 100
 example 5 (Example 28) (Example 26)
 Comparative C2-1 b2 a2 0.3 100% 2871
 69 91
 example 6 (Example 29) (Example 27) charging
 Example 34 C2-2 b2 a2 0.5 by 0.5 C 3812
 95 78
 (Example 29) (Example 27) for 2 hours
 Example 35 C2-3 b2 a2 1.0 .fwdarw. 3998
 101 101
 (Example 29) (Example 27) discharging
 by 0.5 C
 Example 36 C2-4 b2 a2 1.4 to 1.0 V 3910
 100 100
 (Example 29) (Example 27)
 Example 37 C2-5 b2 a2 1.6 3597
 100 101
 (Example 29) (Example 27)
 comparative C2-6 b2 a2 1.7 3324
 102 100
 example 7 (Example 29) (Example 27)
 Comparative C3-1 b3 a3 0.3 100% 2356
 59 92
 example 8 (Comparative (Comparative charging
 example 3) example 2) by 0.5 C
 Comparative C3-2 b3 a3 for 2 hours 2722
 69 84
 example 9 (Comparative (Comparative 0.5 .fwdarw.
 example 3) example 2) discharging
 Comparative C3-3 b3 a3 1.0 by 0.5 C 3205
 81 80
 example 10 (Comparative (Comparative to 1.0 V
 example 3) example 2)
 Comparative C3-4 b3 a3 1.4 3150
 85 85
 example 11 (Comparative (Comparative
 example 3) example 2)
 Comparative C3-5 b3 a3 1.6 3101
 87 86
 example 12 (Comparative (Comparative
 example 3) example 2)
 Comparative C3-6 b3 a3 1.7 3029
 89 85
 example 13 (Comparative (Comparative
 example 3) example 2)
 Furthermore, as to the battery precursor C3-3 of the comparative example
 10, 150% charging was conducted by 0.1 C for 15 hours, and the discharging
 was conducted by 0.5 C until the discharge ending voltage became 1.0V. For
 the obtained battery, similar to the above, the discharge capacity, the
 utilization of the active material, and the capacity recovery ratio were
 measured.
 As a result, the discharge capacity was 2,972 mAh, the utilization of the
 active material was 98%, and the capacity recovery ratio was 85%.
 From the above-mentioned results, the following are explicit.
 (1) The batteries of the comparative examples 8 to 13 containing the active
 material produced not according to the present invention (C3 type) are
 extremely poor compared with the batteries containing the active material
 produced according to the present invention (C1 type and C2 type) in terms
 of the discharge capacity, the utilization and the capacity recovery
 ratio.
 From the above-mentioned, the effectiveness of the active material produced
 by the method of the present invention is apparent.
 (2) However, as apparent from the comparison between the batteries of the
 examples 30 to 33 and the batteries of the comparative examples 4 and 5,
 or between the batteries of the examples 34 to 37 and the batteries of the
 comparative examples 6 and 7, even with the same kind of the active
 material used at the time of producing the battery, the discharge capacity
 30 is declined drastically if the liquid ratio of the electrolysis
 solution to be poured is outside the range from 0.5 to 1.6 cm.sup.3 /Ah.
 From the above-mentioned, it was learned that the liquid ratio of the
 electrolysis solution should be set at 0.5 to 1.6 cm.sup.3 /Ah, even in
 assembling a battery with an active material produced by the method of the
 present invention.
 COMATIVE EXAMPLES 14 TO 19
 An active material of the "embodiment 1" disclosed in the official gazette
 of Japanese Patent Publication Laid-Open No. 9-73900, produced in an open
 hot air convection type device was prepared as an active material a4
 (comparative example 14). Furthermore, only nickel hydroxide particles
 were prepared as an active material a5 (comparative example 15).
 With the active materials, as in the case of the nickel electrodes of the
 example 28 and the example 29, a nickel electrode was produced. The nickel
 electrode using the active material a4 is referred to as the nickel
 electrode b4 (comparative example 16), and the nickel electrode using the
 active material a5 is referred to as the nickel electrode b5 (comparative
 example 17).
 Using the nickel electrodes, battery precursors were assembled as in the
 examples 30 to 37. The battery using the nickel electrode b4 is the
 comparative example 18, and the battery using the nickel electrode b5 is
 the comparative example 19.
 To the assembled battery precursors, 150% initial charging was conducted by
 0.5 C at 25.degree. C., and discharging was conducted by 0.5 C until the
 battery voltage became 1.0 V.
 After charging the batteries by 0.1 C, discharging was conducted by 0.2 C
 until the discharge ending voltage became 1.0V. The discharge capacity
 (actual capacity: mAh) was measured. The utilization of the active
 material (%) was calculated by divided the value by the theoretical
 capacity.
 Moreover, after leaving the battery under the discharge state in the
 atmosphere of 65.degree. C. for 1 month, 150% charging was conducted by
 0.1 C over 15 hours in the atmosphere of 25.degree. C. Then, discharging
 was conducted by 0.2 C until the discharge ending voltage became 1.0V.
 Furthermore, charging was conducted by 1 C for 1.5 hours, and discharging
 was conducted by 1 C until the discharge ending voltage became 1.0V. This
 charging and discharging operation was repeated for 3 cycles. The
 discharge capacity at the time was measured. By dividing the value by the
 initial capacity, the capacity recovery ratio (%) was calculated.
 As a result, the utilization of the active material and the capacity
 recovery ratio of the battery of the comparative example 18 were 93% and
 81% respectively. In the case of the battery of the comparative example
 19, they were 81% and 80%, respectively.
 As heretofore mentioned, according to the method of the present invention,
 an active material with a high utilization in an alkaline secondary
 battery, capable of drastically improving the high ratio discharge
 characteristic of the battery, and restraining the decline of the
 discharge capacity even at the time of recharging after leaving in the
 over discharge state for a long time, can be produced.
 Moreover, since an active material produced by the method of the present
 invention can hardly deteriorate even after a long term storage, it allows
 easy management.
 Furthermore, since a high rate initial charging is allowed for the initial
 charging of a battery assembled with the active material, unlike the
 conventional case with the initial charging with a low rate for a long
 time, the production (initial charging) time of the battery can be
 shortened compared with the conventional case, and thus the production
 efficiency can be improved.
 Moreover, according to the production method of an active material for a
 positive electrode of the present invention, an active material applied
 with the alkaline heat treatment can be processed to a paste with an
 agitating-kneading device used for the production, and the paste can be
 filled directly into the collector after passing through a discharge
 chute.