JP4168578B2 - Square alkaline storage battery and manufacturing method thereof - Google Patents

Description

【００６７】
（表１）に示されるように実施例電池は比較例１，２と比較してリーク不良の割合が大幅に低減しており、従来の角型アルカリ蓄電池の構成方法による比較例３と同レベルであることがわかる。
【００６８】
上記不良電池を解析した結果、溝部を設けなかった比較例１による極板は表面に無差別かつ不規則な位置でクラックが発生して、破損部分がセパレータを貫通したり、活物質粉末がクラック部分から流出して極板とセパレータの間に挟まり微小短絡を発生していることが明らかになった。
【００６９】
また、溝部を設けた比較例２による極板は、比較例１のような無差別なクラックではなく、主として溝部内部にクラックが形成されていたが、上記クラックのバリが表面に隆起して突出していたり、クラックから流出した活物質が溝部の空間を通って極板表面に到達し、セパレータにしみ込んだりしてセパレータと極板の間に入り込み、各所で大小の短絡が発生していることがわかった。
【００７０】
これに対して本発明による実施例の極板を用いた電池では、溝部の底部１０と壁面の交線からクラック１０ａの発生が見られたが、そのクラック場所は溝部活物質層によって封鎖され、活物質の流出やクラック部におけるバリの隆起突出が抑制されていることがわかった。
【００７１】
すなわち、本発明による極板は非焼結式ニッケル極の極板の可とう性の改善、捲回時における短絡の抑制において顕著な効果を示し、そのことにより小さな曲率での折り曲げを行った場合においても高い信頼性を達成することが可能となる。
【００７２】
これにより、従来の技術では、リーク不良が著しく増加するために実現することができなかった非焼結式ニッケル極を用いた捲回構造の電極体が構成可能となり、面倒なセパシール工程や複数の極板を積層・溶接する工程が不要となり、工程の簡略化、生産性の向上が図れる。
【００７３】
本実施例においては、帯状の正極板、負極板をセパレータを介して長円状に捲回して構成した場合について説明を行ったが、図６に示すように長方形状に捲回して構成した場合についても同様の効果が得られる。
【００７４】
以上に示されたように、本発明に基づく、片面に複数の溝部が形成された溝部形成基板層が加圧されてできる溝部活物質層と、緻密な表面層とによってほぼ平滑な表面が構成された非焼結式ニッケル極を、溝部活物質層を備える面を外周として、前記溝部の方向と、正極板の捲回軸とが平行になるように折り曲げて、セパレータを介して負極板と相対向するように積層して角型ケースに収納してなる角型アルカリ蓄電池は、極板構成が簡易であるため生産性に優れ、リーク不良も低減することができる。
【００７５】
【発明の効果】
以上のように本発明によれば、角型構造を有する角型アルカリ蓄電池の課題であった生産性の低さを改善した上で、リーク不良の増加を招くことなく、高い歩留まりを達成することができる。
【図面の簡単な説明】
【図１】本発明の製造方法における正極板作製装置を示す模式図
【図２】同活物質充填基板の断面形状の変化を示す模式図
【図３】同角型アルカリ蓄電池の部分断面拡大図
【図４】同実施例と、比較例１及び比較例２における正極板の平面図
【図５】正極板、負極板、セパレータを長円状に捲回した一般的な電極体の断面図
【図６】正極板、負極板、セパレータを長方形状に捲回した一般的な電極体の断面図
【図７】比較例３における正極板の平面図
【図８】比較例３における正極板、負極板、セパレータを積層した電極体の断面図
【図９】従来の角型アルカリ蓄電池の半裁模式断面図
【符号の説明】
１ 活物質充填基板
２ 溝型付きローラ
３ 平滑ローラ
４ 溝部
５ 溝部形成基板
６ 加圧ローラ
７ 溝部活物質層
８ 電極基板
９ 正極板
９ａ 集電用ニッケルリード
９ｂ リード保護テープ
１０ 溝部の底部
１０ａ溝部底部のクラック
１１ 緻密な表面層
１２ 比較例３の正極板
１２ａ 集電用ニッケルリード
１２ｂ リード保護
１３ 負極板
１４ セパレータ
１５ 電極群
１６ 金属ケース[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a prismatic alkaline storage battery represented by a nickel / hydrogen storage battery and a nickel / cadmium storage battery.
[0002]
[Prior art]
Nickel electrodes used as positive electrodes of alkaline storage batteries represented by nickel / hydrogen storage batteries and nickel / cadmium storage batteries are roughly classified into sintered and non-sintered types.
[0003]
As a method for producing a sintered nickel electrode, a nickel salt solution such as a nickel nitrate aqueous solution is applied to a porous nickel sintered base having a porosity of about 80% obtained by sintering a core material such as punching metal and nickel powder. A general method is to produce nickel hydroxide in a porous nickel sintered base by impregnation and then dipping in an alkaline aqueous solution.
[0004]
Since this electrode plate is filled with a necessary amount of nickel hydroxide as an active material, the above-described impregnation / alkali dipping treatment must be repeated a plurality of times, and the process becomes complicated. In addition, even if the porosity of the porous substrate is increased to increase the packing density of the active material, the strength of the electrode plate is remarkably reduced when the porosity is increased to about 80%, and the active material is likely to fall off. There is a problem that the active material packing density cannot be increased.
[0005]
On the other hand, as a method for producing a non-sintered nickel electrode, a paste in which a foamed nickel porous body having a porosity of 95% or more is used as a base and an active material powder mainly composed of nickel hydroxide is kneaded with water In general, a method is used in which the material is filled through, dried and pressed. This electrode plate has a simpler manufacturing method than a sintered nickel electrode, and a nickel electrode with a high active material packing density can be obtained, so that the capacity of the battery can be increased. Therefore, communication devices, OA, power Currently used in a wide range of fields such as tools.
[0006]
In recent years, electronic devices such as mobile phones have made remarkable progress in miniaturization and thinning, and there has been a demand for miniaturization and thinning of batteries as power sources for driving them. Therefore, there is a growing demand for batteries having a square shape.
[0007]
The square battery is superior in space efficiency when the device is stored as compared with the cylindrical battery. However, when a non-sintered nickel electrode is used for the positive electrode plate to form a prismatic alkaline storage battery, there are the following problems.
[0008]
In general, a prismatic alkaline storage battery has a structure in which a rectangular case 16 accommodates an electrode body in which a plurality of positive plates 12 and negative plates 13 cut into strips are alternately stacked via separators 14. FIG. 9 shows a half-cut schematic cross-sectional view of this rectangular alkaline storage battery.
[0009]
Thus, a prismatic alkaline storage battery that has to be welded with a lead terminal to each of a large number of electrode plates and stacked to form an electrode body is composed of a single strip-like positive electrode plate and negative electrode plate via a separator. Productivity is remarkably inferior compared with a cylindrical alkaline storage battery constituted by winding.
[0010]
In addition, a separator 14 is welded in a bag shape (hereinafter referred to as a separator seal) in order to prevent a minute short-circuit failure (hereinafter referred to as a leakage failure) due to the displacement of the electrode plate on the electrode body having such a laminated structure. to the step of inserting at least one of the positive electrode plate 12 or negative electrode plate 13 is it is essential, and a further complicated ones the configuration of rectangular alkaline蓄 batteries.
[0011]
As a means for improving the productivity of the prismatic battery, a configuration with a winding structure generally used in a prismatic lithium secondary battery, that is, a single strip-like positive electrode plate and negative electrode plate It is conceivable to produce an electrode body by folding the electrodes so as to face each other with a separator interposed between them and store them in a square case.
[0012]
However, in order to accommodate the wound electrode body in the square case, the electrode plate must be wound into an oval shape as shown in FIG. 5 or a rectangular shape as shown in FIG. It is necessary to bend the electrode plate with a very small curvature at the part.
[0013]
However, the non-sintered nickel electrode is originally a structural material with a low degree of freedom of deformation with respect to bending. When it is bent with a small curvature, the nickel core material is cut or cracked on the outer periphery of the bent portion, or the active material is removed. As a result, there is a problem that the leakage failure of the battery increases due to these factors.
[0014]
In order to suppress the cutting or cracking of the bent portion of such a non-sintered nickel electrode with a small curvature or the loss of the active material, for example, V-shaped grooves are formed on both surfaces of the positive electrode plate, Japanese Patent Application Laid-Open No. 60-133655 proposes a technique for winding an electrode plate with its direction parallel to the winding axis.
[0015]
Furthermore, Japanese Patent Laid-Open No. 5-42111 discloses that a groove having a trapezoidal or semi-elliptical cross section is used in place of the groove having a V-shaped cross section in which the metal porous body is easily cut.
[0016]
[Problems to be solved by the invention]
However, with these treatments, the positive electrode plate is improved in flexibility due to the degree of freedom of surface extension given by the groove and the generation of preferential cracks inside the groove, and there is a tendency that the leakage defect is somewhat reduced. However, the effect is not sufficient.
[0017]
This is because, in the configuration in which the groove is formed on the surface of the electrode plate as described above, the burr of the crack generated inside the groove rises and protrudes by the force of winding, or the active material particles pass through the groove from the crack. This is because it flows out to the outer periphery of the electrode plate, and these cause new short circuits.
[0018]
In other words, since the inside of the groove formed on the surface of the active material filled substrate is hollow, it is defenseless against the protruding protrusion of the burr of the crack generated inside the groove and the outflow of the active material from the crack. It becomes a cause of reducing reliability.
[0019]
Thus, in order to bend the non-sintered nickel electrode with a small curvature and produce an electrode body having a wound structure suitable for the configuration of the prismatic alkaline storage battery, a groove is formed in the non-sintered nickel electrode. Not only to improve the flexibility of the electrode plate, but also to produce an appropriate electrode plate structure and the above electrode plate structure to suppress the protruding protrusion of the crack portion and the outflow of active material particles that occur inside the electrode plate Development of an appropriate manufacturing method is required.
[0020]
As described above, there is currently no decisive means for manufacturing a prismatic alkaline storage battery using a non-sintered nickel electrode for the positive electrode, which can achieve both productivity and reduction of leakage defects.
[0021]
[Means for Solving the Problems]
In order to solve the above problems, a prismatic alkaline storage battery according to the present invention comprises a positive electrode plate filled with an active material powder mainly composed of nickel hydroxide in a porous metal body having a three-dimensional space, and a negative electrode plate. In the prismatic alkaline storage battery in which the electrode body formed by laminating and bending at least once through the separator is housed in a square container, the positive electrode plate has a plurality of groove portions on one surface thereof. A groove active material layer having a low active material filling density is formed in the groove, and a smooth surface is constituted by a surface layer having a high active material filling density formed by pressurization, and The surface provided with the groove active material layer is the outer periphery, and the direction of the groove is bent so that the winding axis of the positive electrode plate is parallel.
[0022]
In addition, as a manufacturing method for effectively forming the above-described configuration, an active material filling step of forming a filled substrate by filling a metal porous body having a three-dimensionally continuous space with an active material powder mainly composed of nickel hydroxide. And a step of forming a groove on one side of the filling substrate, a step of pressing the electrode on which the groove is formed almost smoothly to a desired thickness, and a positive electrode plate obtained through the above steps, provided with a groove active material layer A step of forming an electrode body by bending the surface to be an outer periphery and the direction of the groove and the winding axis of the positive electrode plate being parallel to each other and stacking them so as to face the negative electrode plate via a separator; It was set as the manufacturing method characterized by including the process of accommodating a body in a square container, and sealing.
[0023]
Thereby, after improving the low productivity which was the subject of the prismatic alkaline storage battery, a high yield can be achieved without causing an increase in leakage defects.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, a positive electrode plate and a negative electrode plate, in which a metal porous body having a three-dimensionally connected space is filled with an active material powder mainly composed of nickel hydroxide, are interposed via a separator. In the prismatic alkaline storage battery in which the electrode bodies laminated so as to face each other are bent at least once and accommodated in a rectangular container, the positive electrode plate has a plurality of grooves on one surface thereof, and the grooves are groove portions. The cross-sectional shape perpendicular to the shape is a shape in which the wall surface of the shape formed by the outer shape of two arcs and the bottom portion of the groove portion are constituted by a flat portion parallel to the surface, and the groove portion has a low active material filling density. A material layer is formed, and a smooth surface is constituted by a surface layer having a high active material filling density formed by pressurization, and a surface including the groove active material layer is defined as an outer periphery, and the direction of the groove Winding of positive electrode plate Doo is bent so as to be parallel, cracks are formed in the positive electrode plate, which is bent starting from the bottom and the wall of the intersection line of a groove formed in a plurality of parallel, the cracks are pressed by the groove club material layer It is.
[0025]
The manufacturing method for obtaining the square alkaline storage battery of the present invention, by filling an active material powder mainly composed of nickel hydroxide to the metallic porous body having a space leading to the three-dimensional form a positive electrode plate active a material filling step, a step of forming a groove on one surface of the positive electrode plate, said groove, the cross-sectional shape perpendicular to the groove bottom wall and the groove shape formed by two arcs of outer shape A step of forming a shape composed of a flat portion parallel to the surface, and a step of smoothly pressing the positive electrode plate on which the groove is formed with a pair of smooth rollers having an axis perpendicular to the direction of the groove to obtain a desired thickness. And forming the electrode body by laminating the positive electrode plate and the negative electrode plate so as to face each other through a separator with the surface having the groove portion of the positive electrode plate as the outer periphery, and the groove portion of the positive electrode plate The direction of the groove and the front with the provided surface as the outer periphery Bending the electrode body at least once so that the winding axis of the positive electrode plate is parallel to the bent positive electrode plate, and starting from the intersection of the bottoms of the plurality of parallel grooves formed on the positive electrode plate and the wall surface A crack is formed, and the crack includes a step of pressing with a groove active material layer, and a step of housing and sealing the electrode body in a rectangular container .
[0026]
FIG. 3 shows a schematic diagram of the electrode body formed by bending the positive electrode plate of the prismatic alkaline storage battery according to the present invention into an oval shape. 3A is an enlarged view of a bent portion of the positive electrode plate having a small curvature in the electrode body, and FIG. 3B is an enlarged view of a groove formed on the positive electrode plate. is there.
[0027]
Although the positive electrode plate of the prismatic alkaline storage battery according to the present invention has a smooth surface and the grooves are apparently lost, a plurality of the grooves are formed in parallel, so that the flexibility improvement effect is obtained. . Furthermore, the crack site | part formed in the inside of a groove part is pushed out by the groove part active material layer by which pressure molding was carried out, and the protrusion protrusion of a burr | flash and the outflow of an active material can be suppressed.
[0028]
As shown in FIG. 3, the electrode plate is bent so that the surface provided with the groove portion is the outer periphery, and along the groove portion, so that the lithium secondary battery can be used in the prismatic alkaline storage battery without increasing leakage defects. An electrode body having a wound structure similar to that of a battery can be configured.
[0029]
Therefore, it is not necessary to stack a large number of electrode plates as in the prior art, and a complicated separation seal process is not required, so that the electrode plate configuration is simplified and the productivity of the prismatic alkaline storage battery can be improved.
[0030]
It is preferable to use foamed metallic nickel as the metal porous body. By using foamed metallic nickel, a prismatic alkaline storage battery having excellent charge / discharge characteristics and life characteristics can be obtained.
[0031]
As the negative electrode plate, it is preferable to use a punching metal core material coated with a hydrogen storage alloy. Thereby, a high capacity density and a highly reliable prismatic alkaline storage battery can be obtained.
[0032]
【Example】
Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following Example, In the range which does not change the summary, it can change suitably and can implement.
[0033]
(Example 1)
An example of an apparatus for producing a positive electrode plate for a prismatic alkaline storage battery according to the present invention is shown in the schematic view of FIG. The substrate 1 filled with the active material is passed through between the grooved roller 2 having a convex portion and the smoothing roller 3 to become a groove portion forming substrate 5 having the groove portion 4 on one side.
[0034]
Next, when the groove forming substrate 5 is pressed by a pair of smooth pressure rollers 6, the active material oozes out into the groove to form a groove active material layer 7, thereby forming the electrode substrate 8 of the present invention. .
[0035]
The electrode substrate 8 is usually cut perpendicularly to the groove direction to obtain the positive electrode plate 9 according to the present invention.
[0036]
FIG. 2 shows how the active material-filled substrate changes according to the manufacturing process of the present invention in the form of a cross section perpendicular to the groove direction. 2A is an active material-filled substrate, FIG. 2B is a groove forming substrate, and FIG. 2C is an electrode substrate.
[0037]
In the present invention, there are no particular limitations on the thickness, porosity, pore size, pore shape, etc. of the three-dimensional porous body, and existing three-dimensional porous bodies such as foamed metallic nickel can be applied. In this example, a foamed nickel porous body having a porosity of 95% was used.
[0038]
For the production of the active material-filled substrate, a method of using a porous body cut into a strip shape or a flat plate shape in advance and a method of cutting into a plate shape later in an arbitrary process using a continuous band-shaped porous material are used. . The latter is superior for mass productivity.
[0039]
In the present invention, the filling method of the active material is not particularly limited, and any method can be applied as long as the filling can be performed uniformly. For example, for filling the active material, a method of filling the active material by passing the porous substrate through the paste tank of the active material, a method of press-fitting the active material from one side or both sides using a fixed discharge nozzle or a doctor knife, etc. Commonly used existing methods can be applied.
[0040]
As the active material paste, a positive electrode active material paste mainly composed of nickel hydroxide and mixed with necessary additives and a binder is used. In this example, a spherical nickel hydroxide powder in which a small amount of cobalt and zinc are dissolved as a positive electrode active material is prepared, and cobalt hydroxide and zinc oxide as additives are added to the nickel hydroxide in a weight ratio. Were mixed to 8% and 2%, respectively, and water and CMC (carboxymethylcellulose) were added to prepare an active material paste.
[0041]
Next, the groove forming process will be described. By this groove forming process, the cross-sectional shape changes from FIG.
[0042]
In order to form the groove 4 in the belt-shaped active material-filled substrate 1, it is convenient to use the grooved roller 2 and the smooth roller 3 provided with a plurality of ring-shaped convex portions on the circumference of the roller. On one surface of the belt-shaped groove forming substrate 5 obtained by passing through the roller, a plurality of grooves 4 continuous in the traveling direction of the belt-shaped substrate are formed side by side in the width direction.
[0043]
The first purpose of forming the groove part 4 is to apply stress to the bottom part 10 of the groove part, and to generate cracks 10a preferentially in the bottom part 10 of the groove part at the time of winding, and the second purpose is to form a porous body. It is intended to secure a volume for forming a preferable groove active material layer 7 in the groove with the active material exuded from the skeleton.
[0044]
In the electrode plate of the present invention, the state of the groove active material layer that brings about the above-mentioned preferable effect is affected by the form of the substrate on which the groove is formed. For example, it is influenced by the ratio of the groove depth to the thickness of the groove forming substrate, the damage state of the porous substrate in the vicinity of the groove of the groove forming substrate, the shape of the groove, and the like.
[0045]
When the depth ratio of the groove is too small, the improvement effect such as the flexibility of the electrode plate expected by the present invention becomes small. Further, the active material layer inside the groove is insufficient, and the groove active material layer cannot be formed.
[0046]
On the other hand, when it is too large, the skeleton of the porous metal body is easily broken, and the active material inside the groove becomes excessive, and the density of the groove active material layer and its surface layer increases.
[0047]
Next, the groove active material layer forming step will be described.
[0048]
This step is a step of pressurizing the groove forming substrate 5 so that the entire groove forming substrate 5 including the groove forms a substantially smooth surface. Smooth pressure can be easily performed by a pressure roller 6 having a smooth surface. At this time, the cross-sectional shape changes from (B) to (C) in FIG.
[0049]
That is, the groove active material layer 7 is formed in the groove 4 that was hollow at the stage of the groove forming substrate 5, thereby forming the electrode substrate 8 of the present invention.
[0050]
In this step, if the groove forming substrate 5 to be pressed is pressurized in a wet state, the outflow of the active material increases and it becomes difficult to control. Moreover, an active material adheres to a pressurization apparatus, and it may make a pressurization surface non-uniform | heterogenous. Therefore, it is preferable to apply pressure in a dry state.
[0051]
In this step, it is preferable that the pressure is applied with a pressure roller having an axis perpendicular to the groove direction. When pressure is applied with a pressure roller having an axis parallel to the groove direction, that is, when pressure is applied in a direction perpendicular to the groove direction, the groove-forming substrate is stretched or warped, and further the strength of the porous substrate is reduced.
[0052]
The electrode substrate 8 of the present invention is different from the groove forming substrate manufactured by the conventional technique, and the surface of the electrode substrate 8 pressurizes other than the groove active material layer 7 and the groove formed by pressing the groove of the groove forming substrate. Due to the dense surface layer 11 formed by the above, a substantially smooth and dense surface is obtained. In this example, the thickness of the electrode plate after pressurization was adjusted to about 0.7 mm according to the design of the battery to be configured.
[0053]
Next, as shown in FIG. 1, when the desired width dimension of the electrode plate is cut from the length direction of the strip-shaped electrode substrate 8, a plurality of grooves perpendicular to the length direction of the electrode plate are formed in parallel. The positive electrode plate 9 is obtained.
[0054]
In this example, the dimension of the electrode plate after cutting was set to length 38 mm × width 42 mm in accordance with the design of the battery to be configured. Furthermore, the nickel lead 9a for current collection was welded, and the protective tape 9b was affixed to the welding part of this lead 9a, and the positive electrode plate 9 as shown in FIG. 4 was produced.
[0055]
Next, the negative electrode plate 13 was produced as follows. Water, CMC, SBR (styrene-butadiene copolymer) and carbon as a conductive agent are added to a hydrogen storage alloy powder having an alloy composition of MmNi3.8Co0.6Al0.3Mn0.3 (Mm represents Misch metal) and paste. It was applied to both sides of a punching metal core material in which nickel was plated on iron, and this was dried, press-rolled, and then cut into a size of 38 mm length × 62 mm width to obtain a negative electrode plate 13.
[0056]
As shown in FIG. 5, the positive electrode plate 9 and the negative electrode plate 13 manufactured by the above-described method are passed through a separator 14 made of a polypropylene non-woven fabric subjected to a hydrophilization treatment with a basis weight of 60 g / m ² and a thickness of 0.15 mm. It was wound in an oval shape and stored in the square case 16. As shown in FIG. 3, the positive electrode plate 9 is wound in a state where the surface including the groove active material layer 7 is an outer periphery and the groove direction is parallel to the winding axis of the electrode plate.
[0057]
Further, an alkaline electrolyte composed of 6N KOH and 1N LiOH was poured into the case 16 and sealed to assemble 500 prismatic nickel-hydrogen storage batteries having a theoretical capacity of 750 mAh.
[0058]
(Comparative Example 1)
As a comparative example, the same method as shown in the examples except that the thickness of the smooth pressure substrate is 0.7 mm and the electrode plate shape is cut without performing the groove forming step and the groove active material layer forming step. A positive electrode plate was produced. In the same manner as shown in the examples, this positive electrode plate was wound so as to face the negative electrode plate and the separator, and stored in a square case. In the same manner as in the example, the alkaline electrolyte was poured and then sealed, and 500 prismatic nickel-hydrogen storage batteries having a theoretical capacity of 750 mAh were assembled.
[0059]
(Comparative Example 2)
As a comparative example, the present invention except that the thickness of the groove molded substrate is 0.7 mm, the step of forming the groove active material layer is not added, and the depth of the groove is the same as the groove of the positive electrode plate 9 of the present invention. An electrode plate was produced under the same conditions as in the Example. The positive electrode plate 9 was wound so as to face the negative electrode plate 13 and the separator 14 in the same manner as shown in the example, and stored in a square case. In the same manner as in the example, the alkaline electrolyte was poured and then sealed, and 500 prismatic nickel-hydrogen storage batteries having a theoretical capacity of 750 mAh were assembled.
[0060]
(Comparative Example 3)
As a comparative example, an electrode body having a laminated structure, which is a conventional method for forming a prismatic alkaline storage battery, was constructed, and the battery was assembled. The active material paste was filled into the foamed metallic nickel substrate in the same manner as shown in the examples, dried and then pressed to a thickness of about 0.7 mm. Then, it cut | disconnects in the length of 38 mm in length x 14 mm in width | variety, the nickel lead 12a for current collection is welded, the protective tape 12b is stuck on a welding part, and the positive electrode plate 12 as shown in FIG. Produced.
[0061]
Sepa-sealing was performed on the obtained positive electrode plate. The positive electrode plate 12 was housed in a separator 14 made of a polypropylene non-woven fabric and formed into a bag shape by heat welding.
[0062]
Also, the negative electrode plate 13 was coated with a hydrogen storage alloy paste on a punching metal core in the same manner as shown in the examples, dried, press-rolled, and then cut into a size of 38 mm length × 14 mm width. did. Similarly to the positive electrode plate, the negative electrode plate was welded with a nickel lead 12a for current collection, and a protective tape 12b was attached.
[0063]
The obtained separator-sealed positive electrode plate 12 and four negative electrode plates are combined and laminated so as to face each other, and the lead portions are welded so that the positive electrode plates and the negative electrode plates are energized respectively. An electrode body was manufactured. A cross-sectional view showing the configuration state is shown in FIG.
[0064]
The electrode body thus obtained was housed in a square case, and after injecting an electrolyte solution, sealing was performed to assemble 500 square nickel-hydrogen storage batteries having a theoretical capacity of 750 mAh.
[0065]
(Table 1) shows the percentage of leakage failures of the batteries of Examples and Comparative Examples 1, 2, and 3.
[0066]
[Table 1]

[0067]
As shown in (Table 1), the battery of the example has a significantly reduced ratio of leakage failure compared to Comparative Examples 1 and 2, and is at the same level as Comparative Example 3 according to the conventional configuration method of the prismatic alkaline storage battery. It can be seen that it is.
[0068]
As a result of analyzing the defective battery, the electrode plate according to Comparative Example 1 in which no groove portion was provided cracked on the surface indiscriminately and irregularly, and the damaged portion penetrated the separator or the active material powder cracked. It was clarified that a minute short-circuit occurred after flowing out from the portion and sandwiched between the electrode plate and the separator.
[0069]
Further, the electrode plate according to Comparative Example 2 provided with the groove portion was not indiscriminately cracked as in Comparative Example 1, but cracks were mainly formed inside the groove portion. However, the crack burr protruded and protruded from the surface. It was found that the active material flowing out from the cracks reached the electrode plate surface through the space of the groove, soaked into the separator and entered between the separator and the electrode plate, and large and small short circuits occurred in various places. .
[0070]
On the other hand, in the battery using the electrode plate of the example according to the present invention, the generation of the crack 10a was seen from the intersection of the bottom 10 of the groove and the wall surface, but the crack location was sealed by the groove active material layer, It was found that the outflow of the active material and the protruding protrusion of the burr at the crack part were suppressed.
[0071]
That is, the electrode plate according to the present invention has a remarkable effect in improving the flexibility of the electrode plate of the non-sintered nickel electrode, and suppressing the short circuit during winding, and thereby, when bending with a small curvature is performed. It is possible to achieve high reliability even in
[0072]
This makes it possible to construct an electrode body with a wound structure using a non-sintered nickel electrode that could not be realized due to a significant increase in leakage defects in the prior art, and a cumbersome separation process or multiple sealing processes. The process of laminating and welding the electrode plates is no longer necessary, simplifying the process and improving productivity.
[0073]
In the present embodiment, the case where the belt-like positive electrode plate and the negative electrode plate are wound in an oval shape through a separator has been described. However, in the case where the belt is wound in a rectangular shape as shown in FIG. The same effect can be obtained for.
[0074]
As described above, a substantially smooth surface is constituted by a groove active material layer formed by pressurizing a groove forming substrate layer having a plurality of grooves formed on one side and a dense surface layer based on the present invention. The non-sintered nickel electrode is bent with the surface provided with the groove active material layer as the outer periphery so that the direction of the groove and the winding axis of the positive electrode plate are parallel to each other, A prismatic alkaline storage battery that is laminated so as to face each other and accommodated in a prismatic case has a simple electrode plate configuration, and thus is excellent in productivity and can reduce leakage defects.
[0075]
【The invention's effect】
As described above, according to the present invention, it is possible to achieve a high yield without causing an increase in leakage defects while improving the low productivity which has been a problem of the prismatic alkaline storage battery having a prismatic structure. Can do.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a positive electrode plate manufacturing apparatus in the manufacturing method of the present invention. FIG. 2 is a schematic view showing a change in cross-sectional shape of the active material-filled substrate. FIG. 4 is a plan view of a positive electrode plate in the same Example and Comparative Examples 1 and 2. FIG. 5 is a cross-sectional view of a general electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound in an oval shape. 6 is a cross-sectional view of a general electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound in a rectangular shape. FIG. 7 is a plan view of a positive electrode plate in Comparative Example 3. FIG. Cross-sectional view of electrode body with laminated plates and separators [Fig. 9] Half-cut schematic cross-sectional view of a conventional prismatic alkaline storage battery [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Active material filling board | substrate 2 Grooved roller 3 Smooth roller 4 Groove part 5 Groove part formation board 6 Pressure roller 7 Groove part active material layer 8 Electrode board 9 Positive electrode plate 9a Current collecting nickel lead 9b Lead protective tape 10 Groove bottom part 10a Groove part Crack at the bottom 11 Dense surface layer 12 Positive electrode plate 12a of Comparative Example 3 Current collecting nickel lead 12b Lead protection 13 Negative electrode plate 14 Separator 15 Electrode group 16 Metal case

Claims (8)

A porous metal substrate having a three-dimensionally connected space is filled with an active material powder mainly composed of nickel hydroxide, and a pressurized positive electrode plate and negative electrode plate are laminated so as to face each other with a separator interposed therebetween. In the alkaline storage battery in which the electrode body is bent at least once and accommodated in a rectangular container, the positive electrode plate has a plurality of groove portions on one surface thereof , and the groove portion has a cross-sectional shape perpendicular to the groove portion of 2 The wall surface of the shape formed by the outer shape of the two arcs and the bottom portion of the groove portion is a shape composed of a flat portion parallel to the surface, a groove active material layer having a low active material filling density is formed in the groove portion, A smooth surface is constituted by the surface layer having a high active material filling density formed by pressurization, and the surface including the groove active material layer is defined as an outer periphery, the direction of the groove, and the winding axis of the positive electrode plate So that they are parallel Ri bent, cracked the form line of intersection of the positive electrode plate which is bent and the bottom of the groove formed in a plurality of parallel walls starting squareness alkaline storage battery wherein the cracks are pressed by the groove club material layer . The prismatic alkaline storage battery according to claim 1, wherein the porous metal body is foamed metallic nickel. The prismatic alkaline storage battery according to claim 1, wherein the negative electrode plate is a punched metal core coated with a hydrogen storage alloy. 2. The prismatic alkaline storage battery according to claim 1, wherein one surface of the positive electrode plate has a surface layer having a high active material packing density and a groove active material layer having a low active material packing density alternately and in parallel alternately. . An active material filling step of filling a metal porous body having a three-dimensionally connected space with an active material powder mainly composed of nickel hydroxide to form a positive electrode plate;
Forming a groove on one surface of the positive electrode plate , wherein the groove has a cross-sectional shape perpendicular to the groove and is formed by two circular arcs and a flat surface in which the bottom of the groove is parallel to the surface A step of forming a shape composed of parts,
A step of smoothly pressing the positive electrode plate having the groove portion with a pair of smooth rollers having an axis perpendicular to the groove direction to a desired thickness;
A step of forming the positive electrode plate groove in the outer peripheral surface provided with the said positive and negative electrode plates and a and by Uni laminated you opposed via a separator electrode body,
Wherein a step of bending at least once the electrode body so wound and Kaijiku is parallel to the groove to the direction of the groove as the outer peripheral surface provided with the positive electrode plate of the positive electrode plate, a positive electrode plate, which is bent A crack starting from the intersection of the bottom and wall surface of the plurality of grooves formed in parallel is formed,
The crack is pressed by the groove active material layer;
A method for producing a prismatic alkaline storage battery, comprising: storing the electrode body in a rectangular container and sealing the same. 6. The method for producing a prismatic alkaline storage battery according to claim 5, wherein a groove portion active material layer having a low active material filling density and a surface layer having a high active material filling density alternately form a smooth surface in the groove portion. The method for producing a prismatic alkaline storage battery according to claim 5 , wherein the porous metal body is foamed metallic nickel. 6. The method for producing a prismatic alkaline storage battery according to claim 5 , wherein the negative electrode plate is formed by coating a hydrogen storage alloy on the punching metal core.

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