JP2010123455A - Method for manufacturing negative electrode mixture paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a negative electrode mixture paste for obtaining the negative electrode mixture paste in which hydrogen storing alloy powders and other negative electrode materials are dispersed uniformly. <P>SOLUTION: The method for manufacturing the negative electrode mixture paste includes a dehydration process (step S4) of carrying out dehydration treatment on a slurry 50 composed of the hydrogen storing alloy powders and water, and of forming a dehydrated cake of water content of 5.5 wt.% or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a negative electrode mixture paste containing hydrogen storage alloy powder.

In recent years, various batteries have been developed. For example, nickel-metal hydride storage batteries are rapidly spreading as secondary batteries having high energy density and excellent reliability.
In a nickel metal hydride storage battery, for example, a negative electrode plate produced by applying a negative electrode mixture paste containing a hydrogen storage alloy powder to a nickel-plated steel plate (punching metal), drying, and pressing is used. Among these, various methods are proposed as a manufacturing method of the negative mix paste containing a hydrogen storage alloy (for example, refer patent document 1).

JP 2006-92902 A

  Patent Document 1 discloses the following manufacturing method. The hydrogen storage alloy powder is obtained by pulverizing the hydrogen storage alloy in water to an average particle size of 30 μm with a wet ball mill. Next, the hydrogen storage alloy powder and the aqueous alkali solution are put into a stirring vessel and mixed, and the mixture is stirred for 15 minutes to subject the hydrogen storage alloy powder to an alkali treatment. Next, the alkali-treated mixture is introduced into a pressure filtration tank, pressurized to discharge the aqueous alkali solution, and washed with a large amount of water to obtain an alkali-treated hydrogen storage alloy powder. Next, a CMC aqueous solution and ketjen black are added to and kneaded with the hydrogen storage alloy powder, and then an SBR aqueous solution is added and stirred to obtain a negative electrode mixture paste.

  By the way, when the hydrogen storage alloy powder after the alkali treatment is washed with a large amount of water, the hydrogen storage alloy powder becomes a slurry together with water. Patent Document 1 does not specifically describe the slurry dewatering method, but it is considered that the slurry is dewatered by some method.

  However, it is difficult to completely remove water by dehydrating a slurry composed of hydrogen storage alloy powder and water. Therefore, water remains in the dehydrated cake (soft solid material comprising hydrogen storage alloy powder and water) obtained by dehydrating the slurry. If the moisture content of the dehydrated cake is high, a thickener (such as CMC aqueous solution) and a conductive agent (such as Ketjen Black) will be added and kneaded. A granular lump) may occur. For this reason, the hydrogen storage alloy powder or the like may not be uniformly dispersed. Therefore, a negative electrode mixture paste in which hydrogen storage alloy powder or the like is uniformly dispersed may not be obtained.

  The present invention has been made in view of the current situation, and provides a method for producing a negative electrode mixture paste capable of obtaining a negative electrode mixture paste in which a hydrogen storage alloy powder and other negative electrode materials are uniformly dispersed. For the purpose.

  The solution is a method for producing a negative electrode mixture paste, comprising a dehydration step of dehydrating a slurry comprising a hydrogen storage alloy powder and water to produce a dehydrated cake having a moisture content of 5.5 wt% or less. It is a manufacturing method of an agent paste.

In the production method of the present invention, in the dehydration step, the slurry comprising the hydrogen storage alloy powder and water is dehydrated to produce a dehydrated cake having a moisture content of 5.5 wt% or less. In this way, by setting the moisture content of the dehydrated cake to 5.5 wt% or less, the dehydrated cake and other negative electrode materials (a conductive agent such as ketjen black or a thickener such as a CMC aqueous solution) are then kneaded. In the kneading step, generation of lumps can be suppressed, and the hydrogen storage alloy powder and other negative electrode materials can be uniformly dispersed. Thereby, a negative electrode mixture paste in which hydrogen storage alloy powder and other negative electrode materials are uniformly dispersed can be obtained.
The dehydrated cake is obtained by dehydrating a slurry made of hydrogen storage alloy powder and water, and is a soft solid made of hydrogen storage alloy powder and water.

  Furthermore, in the method for producing the negative electrode mixture paste, the dehydration step is performed by pressurizing the slurry with an inert gas supplied into the filtration chamber in a state where the slurry is disposed in the filtration chamber including a filter medium. A method for producing a negative electrode mixture paste in which water contained in the slurry is discharged out of the filtration chamber through the filter medium is preferable.

Since the hydrogen storage alloy powder has high activity, for example, it is dangerous to heat the slurry in the dehydration step and perform the dehydration process because it may ignite.
On the other hand, in the production method of the present invention, in the dehydration step, the slurry is pressurized with an inert gas (such as nitrogen gas) supplied into the filtration chamber in a state where the slurry is disposed in the filtration chamber including the filter medium. The contained water is discharged out of the filtration chamber through the filter medium. According to such a dehydration technique, there is no possibility that the hydrogen storage alloy powder is ignited and it is safe.

  Furthermore, in the above method for producing a negative electrode mixture paste, the filter medium may be a method for producing a negative electrode mixture paste that is a woven fabric made of water-repellent monofilaments.

In the production method of the present invention, a woven fabric made of water-repellent monofilament is used as the filter medium provided in the above-described filtration chamber. By using this woven fabric as a filter medium, the water content of the dehydrated cake can be appropriately reduced to 5.5 wt% or less.
Examples of the water-repellent monofilament include polypropylene monofilament.

Next, the manufacturing method of the negative mix paste concerning embodiment of this invention is demonstrated, referring drawings.
First, the manufacturing apparatus 1 which manufactures negative mix paste is demonstrated. FIG. 1 is a schematic diagram of the manufacturing apparatus 1. The manufacturing apparatus 1 includes a stirring device 10, a water washing device 20, a pressure dehydrating device 30, and a kneading device 40.

  Among these, the stirring apparatus 10 is an apparatus which stirs the mixture of hydrogen storage alloy powder and aqueous alkali solution (for example, sodium hydroxide aqueous solution), and performs the alkali treatment of hydrogen storage alloy powder. The stirring device 10 is provided with a heating means (not shown), and the temperature of the mixture of the hydrogen storage alloy powder and the alkaline aqueous solution can be maintained at a constant value (for example, 90 ° C.) by the heating means. . By this alkali treatment, the surface of the hydrogen storage alloy powder can be activated.

  The alkaline aqueous solution supplied into the stirring device 10 is preferably an aqueous solution of NaOH and / or KOH. This is because NaOH and KOH have high ionization degrees of 0.89 and 0.84, respectively, so that efficient alkali treatment is possible.

  The water washing apparatus 20 is an apparatus for washing the hydrogen storage alloy powder after the alkali treatment performed using the stirring apparatus 10 with water. Specifically, after supplying the hydrogen storage alloy powder after the alkali treatment into the water washing apparatus 20, pure water is supplied into the water washing apparatus 20. Thereafter, the supernatant (alkaline aqueous solution) is discharged outside the water washing apparatus 20. This operation is repeated until the pH of the supernatant discharged from the water washing apparatus 20 reaches a reference value (for example, pH 10).

  The pressure dehydrating device 30 is a device that pressurizes and dehydrates the slurry (a slurry made of hydrogen storage alloy powder and water) accommodated in the water washing device 20 after the water washing is completed. Specifically, as shown in FIG. 2, the pressurized dehydration apparatus 30 is connected to a filtration chamber 31, a nitrogen gas supply unit 32 connected to the ceiling 31 b of the filtration chamber 31, and a bottom 31 c of the filtration chamber 31. The drainage part 33 is provided. A filter medium 35 is disposed on the bottom 31 c of the filtration chamber 31. In this embodiment, a woven fabric made of polypropylene monofilament is used as the filter medium 35. Nitrogen gas (inert gas) can be supplied into the filtration chamber 31 through the nitrogen gas supply unit 32. The water that has passed through the filter medium 35 can be discharged to the outside of the filtration chamber 31 through the drainage part 33.

  In the present embodiment, the dehydration treatment of the slurry 50 composed of the hydrogen storage alloy powder and water is performed using the pressure dehydration apparatus 30 as follows. First, the slurry (the slurry 50 made of hydrogen storage alloy powder and water) accommodated in the water washing apparatus 20 after completion of the water washing is supplied into the filtration chamber 31 of the pressure dehydration apparatus 30. At this time, the slurry 50 is arrange | positioned on the surface 35b of the filter medium 35, as shown in FIG. In this state, nitrogen gas is supplied into the filtration chamber 31 through the nitrogen gas supply unit 32, and the atmospheric pressure in the filtration chamber 31 is increased to about 290 kPa. Thereby, the slurry 50 in the filtration chamber 31 can be pressurized (pressed toward the filter medium 35) with nitrogen gas. At this time, the water contained in the slurry 50 passes through the filter medium 35 and is then discharged to the outside of the filtration chamber 31 through the drainage part 33.

  In the present embodiment, the pressure dehydration process (pressing the slurry 50 with nitrogen gas) is performed for 6600 seconds (110 minutes). In the filtration chamber 31 (on the surface 35b of the filter medium 35) after the pressure dehydration treatment, a dehydrated cake (soft solid material composed of hydrogen storage alloy powder and water) having a moisture content of 5.5 wt% or less remains.

  The kneading apparatus 40 is an apparatus for preparing a negative electrode mixture paste by kneading a dehydrated cake generated by pressure dehydration and other negative electrode materials (such as a conductive agent, a thickener, and a binder). is there. In this embodiment, since a dehydrated cake having a moisture content of 5.5 wt% or less is used, the formation of lumps (a large amount of hydrogen storage alloy powder or the like formed into a granular lump) during kneading is suppressed. be able to. Thereby, a negative electrode mixture paste in which a negative electrode material such as hydrogen storage alloy powder is uniformly dispersed can be obtained.

  Note that the conductive agent is not particularly limited as long as it is a material having electronic conductivity. For example, graphite such as natural graphite (such as flake graphite), artificial graphite, expanded graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber In addition, conductive fibers such as metal fibers, metal powders such as copper, organic conductive materials such as polyphenylene derivatives, and the like can be used. Among these, artificial graphite, ketjen black, and carbon fiber are preferable, but these materials may be mixed and used.

  Moreover, as a thickener, what can provide viscosity to a negative mix paste can be used. Examples include carboxymethylcellulose (CMC) and modified products thereof, polyvinyl alcohol, methylcellulose, polyethylene oxide, and the like.

As the binder, either a thermoplastic resin or a thermosetting resin may be used. For example, styrene-butadiene copolymer rubber (SBR), polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene -Perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride -Pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoro Propylene - tetrafluoroethylene copolymer, vinylidene fluoride - perfluoromethyl vinyl ether - tetrafluoroethylene copolymer, ethylene - acrylic acid copolymer, ethylene - acrylic acid copolymer Na ⁺ ion crosslinking body, an ethylene - methacrylic acid Copolymer, ethylene-methacrylic acid copolymer Na ⁺ ion crosslinked product, ethylene-methyl acrylate copolymer, ethylene-methyl acrylate copolymer Na ⁺ ion crosslinked product, ethylene-methyl methacrylate copolymer, ethylene -Methyl methacrylate copolymer Na ⁺ ion crosslinked body etc. can be used individually or in mixture.

Next, the manufacturing method of the negative electrode mixture paste of this embodiment will be described in detail. FIG. 3 is a flowchart showing a flow of a method for producing a negative electrode mixture paste according to the present embodiment.
First, in step S1 (pulverization step), a mass of the hydrogen storage alloy is pulverized to obtain a hydrogen storage alloy powder having an average particle size of 30 μm. Specifically, the mass of the hydrogen storage alloy was pulverized in water using a wet ball mill. In the present embodiment, a hydrogen storage alloy represented by a composition formula of MmNi _3.55 Co _0.75 Mn _0.4 Al _0.3 (Mm is a mixture of light rare earth elements) is used as the hydrogen storage alloy.

  Subsequently, it progresses to step S2 (alkali treatment process), and the alkali treatment of the hydrogen storage alloy powder obtained by step S1 is performed. Specifically, first, 480 kg of the hydrogen storage alloy powder obtained in step S <b> 1 is charged into the stirring device 10. Next, 480 kg of a 20 wt% aqueous sodium hydroxide solution is supplied into the stirring device 10. Thereafter, this mixture was stirred for 50 minutes by heating means (not shown) while maintaining the temperature of the mixture (mixture of hydrogen storage alloy powder and alkaline aqueous solution) accommodated in the stirring device 10 at 90 ° C. Thereby, the alkali treatment of the hydrogen storage alloy powder was performed, and the surface of the hydrogen storage alloy powder was activated.

  Next, it progresses to step S3 (water washing process), and the hydrogen storage alloy powder which finished the process (alkali treatment) of step S2 is washed with water. Specifically, first, a mixture of the hydrogen storage alloy powder and the sodium hydroxide aqueous solution housed in the stirring device 10 is supplied into the water washing device 20. Thereafter, the mixture is allowed to stand for a predetermined time to precipitate the hydrogen storage alloy powder, and then the supernatant liquid (aqueous sodium hydroxide solution) is discharged outside the water washing apparatus 20. Next, 800 kg of pure water is supplied into the water washing apparatus 20. Thereafter, after standing for a predetermined time to precipitate the hydrogen storage alloy powder, the supernatant liquid (aqueous sodium hydroxide solution) is discharged to the outside of the water washing apparatus 20. Thereafter, the supply of pure water into the rinsing apparatus 20 and the discharge of the supernatant liquid from the rinsing apparatus 20 are repeated, and the pH of the supernatant liquid discharged from the rinsing apparatus 20 is the reference value (pH 10 in this embodiment). The process of step S3 is complete | finished when reaching to. At this time, the slurry containing the hydrogen storage alloy powder and water remains in the water washing apparatus 20.

  Next, the process proceeds to step S4 (dehydration step), and the slurry 50 composed of the hydrogen storage alloy powder and water is dehydrated. Specifically, first, the slurry remaining in the water washing apparatus 20 (the slurry 50 made of hydrogen storage alloy powder and water) is supplied into the filtration chamber 31 of the pressure dehydration apparatus 30. At this time, the slurry 50 is arrange | positioned on the surface 35b of the filter medium 35, as shown in FIG. In this state, nitrogen gas is supplied into the filtration chamber 31 through the nitrogen gas supply unit 32, and the atmospheric pressure in the filtration chamber 31 is increased to about 290 kPa. Thereby, the slurry 50 in the filtration chamber 31 can be pressurized (pressed toward the filter medium 35) with nitrogen gas. At this time, the water contained in the slurry 50 passes through the filter medium 35 and is then discharged to the outside of the filtration chamber 31 through the drainage part 33.

  In the present embodiment, the pressure dehydration process (pressurization of the slurry 50 with nitrogen gas) is performed for 6600 seconds (110 minutes). In the filtration chamber 31 (on the surface 35b of the filter medium 35) after the pressure dehydration treatment, a dewatered cake (soft solid material composed of hydrogen storage alloy powder and water) having a moisture content of 5.5 wt% or less remains.

  Next, the process proceeds to step S5 (kneading step), and the dehydrated cake generated in step S4 and other negative electrode materials (conductive agent, thickener, binder, etc.) are kneaded, and the negative electrode mixture paste Is made. Specifically, first, 1 kg of dehydrated cake is put into the kneading apparatus 40. Next, a mixed aqueous solution prepared by mixing 1.7 g of CMC, 3.3 g of ketjen black, 11.0 g of yttrium oxide, and 84 g of water was prepared. To supply. Thereafter, the dewatered cake and the mixed aqueous solution are kneaded in the kneading apparatus 40.

  Next, 15 g of a 48 wt% aqueous SBR (styrene-butadiene copolymer rubber) solution is supplied into the kneading apparatus 40 and further kneaded. Thereby, a negative electrode mixture paste in which a negative electrode material such as hydrogen storage alloy powder is uniformly dispersed can be obtained. Thus, a negative electrode plate is produced using a negative electrode mixture paste in which a negative electrode material such as hydrogen storage alloy powder is uniformly dispersed, and a battery is produced using this negative electrode plate, so that the charge / discharge characteristics of the battery are good. Can be.

(Production of battery)
Next, the nickel metal hydride storage battery 100 (see FIG. 5) was produced using the negative electrode mixture paste produced as described above.
First, as shown in FIG. 4, the negative electrode mixture paste 60 produced as described above was applied to the inside and on both sides of the through-hole 171b of the nickel-plated steel plate 171 having a large number of through-holes 171b. Thereafter, the negative electrode mixture paste 60 was dried and pressed to prepare the negative electrode plate 170. Further, a positive electrode mixture paste containing nickel hydroxide was filled into a foamed nickel substrate, dried and compression-molded to produce a positive electrode plate 160. Thereafter, the plurality of positive plates 160 and the plurality of negative plates 170 were alternately stacked with the separators 180 sandwiched one by one to form the electrode body 150.

  Next, the electrode body 150 is accommodated in a rectangular box-shaped battery case 111 made of a nickel-plated steel plate, welded to a positive electrode terminal and a negative electrode terminal (not shown), and then an electrolytic solution (an alkaline aqueous solution containing KOH as a main component) is charged. It was injected into the tank 111. Thereafter, the opening of the battery case 111 was sealed with a sealing plate 115 provided with a safety valve device 113. In this way, a nickel metal hydride storage battery 100 (see FIG. 5) was produced. Since the nickel metal hydride storage battery 100 of this embodiment has the negative electrode plate 170 manufactured using the negative electrode mixture paste in which the negative electrode material such as hydrogen storage alloy powder is uniformly dispersed, the charge / discharge characteristics are improved.

(Examples and comparative examples)
First, as an example, the manufacturing apparatus 1 was used to perform the processes of steps S1 to S5 described above, thereby preparing a negative electrode mixture paste according to the example. In step S4 (dehydration step), when the pressure in the filtration chamber 31 of the pressure dehydration apparatus 30 was measured during the period in which the slurry 50 was pressurized with nitrogen gas, the internal pressure set to about 290 kPa gradually decreased, and finally The pressure dropped to about 170 kPa.

  After the treatment of step S4 (dehydration step), the obtained dehydrated cake was examined. As a result, small through holes were formed from the surface of the dehydrated cake to the back surface (the surface in contact with the filter medium 35). This through hole is considered to be the cause of lowering the atmospheric pressure in the filtration chamber 31. That is, the through hole is formed while the slurry is pressurized with nitrogen gas, and a part of the nitrogen gas in the filtration chamber 31 passes through the through hole and the filter medium 35 and is discharged to the outside of the filtration chamber 31. It is thought that it was done.

Furthermore, when the moisture content of the dewatering cake concerning an Example was calculated, it was 5.5 wt%. The moisture content (%) of the dehydrated cake was calculated based on the following calculation formula (1).
Water content of dehydrated cake = {(weight of dehydrated cake−weight of hydrogen storage alloy during drying) / weight of dehydrated cake} × 100 (1)
The weight of the hydrogen storage alloy at the time of drying is a dry weight after the dehydrated cake is dried at 90 ° C. for 15 minutes under reduced pressure.

  In particular, in this example, when the dehydrated cake and the mixed aqueous solution (CMC, ketjen black, yttrium oxide, and water) were kneaded in Step S5 (kneading step), no lumps occurred. That is, the negative electrode material such as hydrogen storage alloy powder could be uniformly dispersed. Thereafter, an aqueous SBR solution was added and further kneaded to obtain a negative electrode mixture paste in which a negative electrode material such as hydrogen storage alloy powder was uniformly dispersed.

Next, a negative electrode mixture paste according to a comparative example was produced. Specifically, using the manufacturing apparatus in which only the filter medium of the pressure dehydration apparatus 30 was changed in the manufacturing apparatus 1, the above-described steps S1 to S5 were performed, and a negative electrode mixture paste according to a comparative example was produced. .
In the pressure dehydrating apparatus of this comparative example, instead of the filter medium 35 (woven cloth made of polypropylene monofilament) of the embodiment, a woven cloth made of polyamide multifilament is used as the filter medium. That is, a woven fabric made of hydrophilic multifilament is used as the filter medium.

  Even in this comparative example, in step S4 (dehydration process), when the pressure in the filtration chamber of the pressure dehydration apparatus was measured during the period in which the slurry was pressurized with nitrogen gas, the internal pressure set to about 290 kPa gradually decreased, Eventually it dropped to about 120 kPa. Thus, in this comparative example, the pressure inside the filtration chamber was 50 kPa lower than that of the example.

  After the treatment of step S4 (dehydration step), the obtained dehydrated cake was examined. As a result, a large number of through holes were formed from the surface of the dehydrated cake to the back surface (surface in contact with the filter medium). The number of through holes was larger than that of the example, and the size of the through holes was larger than that of the example. For this reason, in this comparative example, it is thought that the atmospheric | air pressure in a filtration chamber became lower than the Example.

  Furthermore, when the moisture content of the dewatered cake according to the comparative example was calculated based on the calculation formula (1) in the same manner as in the example, it was 5.6 wt%. That is, the moisture content of the dehydrated cake according to the comparative example was 0.1 wt% higher than that of the example. This is considered to be due to the fact that the pressure in the filtration chamber was 50 kPa lower than in the example in step S4 (dehydration process). That is, in this comparative example, since the force which pressurizes the slurry in a filtration chamber with nitrogen gas (presses it toward a filter medium) became smaller than the Example, it is thought that the dehydration capability fell.

  Since the Example and the Comparative Example differ only in the filter medium of the pressure dehydration apparatus, it can be said that the difference in the dewatering ability is due to the difference in the filter medium. From this result, in step S4 (dehydration step), when a woven fabric made of water-repellent monofilament (polypropylene monofilament) is used as the filter medium, the moisture content of the dehydrated cake is appropriately 5.5 wt% or less. It can be said that. On the other hand, when a woven fabric made of hydrophilic multifilament (polyamide multifilament) is used, it can be said that the moisture content of the dehydrated cake cannot be reduced to 5.5 wt% or less.

  It is considered that the difference in the dehydration ability due to the difference in the filter media is caused by the following reasons. When a woven fabric made of hydrophilic multifilament is used as the filter medium, water contained in the slurry 50 easily passes through the filter medium. For this reason, when the slurry 50 is pressed with nitrogen gas, water is rapidly removed from the slurry 50, so that the slurry (hydrogen storage alloy powder) is separated at that portion, thereby forming a through hole. Therefore, in the comparative example using a woven fabric made of hydrophilic multifilament as a filter medium, it is considered that many large through holes are formed in the dewatered cake and the dewatering ability is lowered.

  On the other hand, when a woven fabric made of water-repellent monofilament is used as the filter medium, water contained in the slurry 50 is difficult to pass through the filter medium. For this reason, when the slurry 50 is pressed with nitrogen gas, water is slowly removed from the slurry 50, so that it is difficult for the slurry (hydrogen storage alloy powder) to be separated, thereby making it difficult to form a through hole. Therefore, in the Example using the woven fabric which consists of a water-repellent monofilament as a filter medium, it is thought that the reduction | decrease in the dehydration capability could be suppressed and the moisture content of the dewatered cake could be 5.5 wt% or less. .

  Further, in the comparative example, when the dehydrated cake and the mixed aqueous solution (CMC, ketjen black, yttrium oxide, and water) were kneaded in Step S5 (kneading step), many lumps occurred. For this reason, negative electrode materials, such as hydrogen storage alloy powder, were not able to be disperse | distributed uniformly. Thereafter, even when the SBR aqueous solution was added and further kneaded, the lumps remained. Therefore, a negative electrode mixture paste in which a negative electrode material such as hydrogen storage alloy powder is uniformly dispersed cannot be obtained.

  The reason for this is considered that the moisture content of the dehydrated cake was not 5.5 wt% or less. This is because only the moisture content of the dehydrated cake is different in the kneading process of the example and the comparative example. From the above results, by setting the moisture content of the dehydrated cake generated in step S4 (dehydration process) to 5.5 wt% or less, generation of lumps can be suppressed in step S5 (kneading process), and hydrogen It can be said that a negative electrode mixture paste in which the storage alloy powder and the like are uniformly dispersed can be obtained.

  In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.

It is a schematic diagram of the manufacturing apparatus concerning embodiment. It is a schematic diagram of a pressure dehydration device concerning an embodiment. It is a flowchart which shows the flow of the manufacturing method of the negative mix paste concerning embodiment. It is sectional drawing which shows the state which apply | coated the negative mix paste 60 to the nickel plating steel plate 171. FIG. 1 is a partially broken perspective view of a nickel metal hydride storage battery 100 according to an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 30 Pressure dehydration apparatus 31 Filtration chamber 35 Filter medium 50 Slurry 60 Negative electrode mixture paste 100 Nickel metal hydride storage battery 170 Negative electrode plate

Claims (3)

A method for producing a negative electrode mixture paste,
A method for producing a negative electrode mixture paste comprising a dehydration step of dehydrating a slurry comprising a hydrogen storage alloy powder and water to produce a dehydrated cake having a water content of 5.5 wt% or less. It is a manufacturing method of the negative mix paste of Claim 1,
The dehydration step includes
A negative electrode mixture that pressurizes the slurry with an inert gas supplied into the filtration chamber and discharges water contained in the slurry to the outside of the filtration chamber through the filter medium in a state where the slurry is disposed in the filtration chamber including the filter medium. Manufacturing method of paste. It is a manufacturing method of the negative mix paste of Claim 2,
The said filter medium is a manufacturing method of the negative mix paste which is a woven fabric which consists of a water-repellent monofilament.

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