JP2009187886A - Method of manufacturing cadmium negative electrode of alkaline storage battery - Google Patents

Method of manufacturing cadmium negative electrode of alkaline storage battery Download PDF

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JP2009187886A
JP2009187886A JP2008029040A JP2008029040A JP2009187886A JP 2009187886 A JP2009187886 A JP 2009187886A JP 2008029040 A JP2008029040 A JP 2008029040A JP 2008029040 A JP2008029040 A JP 2008029040A JP 2009187886 A JP2009187886 A JP 2009187886A
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active material
cadmium
paste
negative electrode
copper
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Kazuki Onoda
一城 小野田
Takeya Ito
剛也 伊藤
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Sanyo Electric Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of obtaining a cadmium negative electrode of an alkaline storage battery which can improve an active material utilization rate without increasing the number of new processes. <P>SOLUTION: In the method of manufacturing the cadmium negative electrode 11 of an alkaline storage battery, the cadmium negative electrode 11 is formed by applying an active material paste containing a cadmium active material made of cadmium oxide as a major constituent and an organic high-polymer paste agent to an electrode substrate 11a. In this case, the manufacturing method includes an addition process of adding pyrophosphoric acid copper (Cu<SB>2</SB>P<SB>2</SB>O<SB>7</SB>) into the cadmium paste agent made of metal cadmium as a preliminary charged active material and the organic high-polymer paste agent as the major constituents, an active material paste preparation process of preparing the active material paste by kneading the cadmium paste agent added with the pyrophosphoric acid copper (Cu<SB>2</SB>P<SB>2</SB>O<SB>7</SB>) and the cadmium oxide (CdO) used as a main active material, and an active material applying process of forming an active material applied layer 11b by applying the active material paste to the electrode substrate 11a made of a conductive core. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、少なくとも酸化カドミウムを主体とするカドミウム活物質と有機高分子糊料とを含有する活物質ペーストを電極基板に塗布して形成するアルカリ蓄電池用カドミウム負極の製造方法に関する。   The present invention relates to a method for producing a cadmium negative electrode for an alkaline storage battery, wherein an active material paste containing at least a cadmium active material mainly composed of cadmium oxide and an organic polymer paste is applied to an electrode substrate.

従来、ニッケル−カドミウム蓄電池に用いられるカドミウム負極には焼結式負極と非焼結式負極とがある。焼結式負極はニッケル粉末を焼結して形成したニッケル焼結基板に水酸化カドミウム（Ｃｄ（ＯＨ）2）を主体とするカドミウム活物質を充填して作製されるものである。一方、非焼結式負極は酸化カドミウム（ＣｄＯ）を主体とするカドミウム活物質と有機高分子糊料や合成繊維等とを混練して活物質ペーストを調製し、この活物質ペーストをパンチングメタル等の導電性芯体（電極基板）に塗布して作製されるものである。 Conventionally, cadmium negative electrodes used in nickel-cadmium storage batteries include sintered negative electrodes and non-sintered negative electrodes. The sintered negative electrode is manufactured by filling a nickel sintered substrate formed by sintering nickel powder with a cadmium active material mainly composed of cadmium hydroxide (Cd (OH) 2 ). On the other hand, a non-sintered negative electrode is prepared by kneading a cadmium active material mainly composed of cadmium oxide (CdO) with an organic polymer paste or synthetic fiber to prepare an active material paste. It is produced by applying to a conductive core (electrode substrate).

近年、電動工具等のコードレス機器においてニッケル−カドミウム蓄電池が使用されているが、それら機器の小型化・高出力化の流れを受け、ニッケル−カドミウム蓄電池に対して高容量化、高充填密度化が要請されている。そこで、ニッケル正極、カドミウム負極の特性を向上させるための開発が種々行われてきた。   In recent years, nickel-cadmium storage batteries have been used in cordless devices such as electric tools. However, due to the trend toward miniaturization and higher output of these devices, higher capacity and higher packing density have been achieved for nickel-cadmium storage batteries. It has been requested. Thus, various developments have been made to improve the characteristics of the nickel positive electrode and the cadmium negative electrode.

その一つとして、充電効率を向上させて活物質利用率を高めるための種々の提案がなされるようになった。例えば、特許文献１（特開平２−３００６６号公報）においては、カドミウム負極に酸化銅（ＣｕＯ）を固形添加することにより、カドミウム負極の充電効率を向上させることが提案されている。   As one of them, various proposals for improving the charging efficiency and increasing the active material utilization rate have been made. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2-30066) proposes improving the charging efficiency of a cadmium negative electrode by adding copper oxide (CuO) to the cadmium negative electrode in a solid form.

また、特許文献２（特開昭６３−３０８８７２号公報）においては、カドミウム負極を硫酸銅（ＣｕＳＯ4）溶液などの銅塩溶液に浸漬し、それをアルカリ電解液中で陰電解して予備放電を行うとともに、銅塩の一部あるいは全部を金属銅に変換することにより、カドミウム負極に金属銅の導電性マトリックスを形成する方法が提案されている。
特開平２−３００６５号公報 特開昭６３−３０８８７２号公報 In Patent Document 2 (Japanese Patent Laid-Open No. 63-308772), a cadmium negative electrode is immersed in a copper salt solution such as a copper sulfate (CuSO 4 ) solution, and is subjected to a negative discharge in an alkaline electrolyte to perform a preliminary discharge. And a method of forming a conductive matrix of metallic copper on the cadmium negative electrode by converting a part or all of the copper salt into metallic copper.
Japanese Patent Laid-Open No. 2-30065 Japanese Unexamined Patent Publication No. 63-308872

しかしながら、上述した特許文献１にて提案されたカドミウム負極にあっては、酸化銅（ＣｕＯ）は固形添加であるため、カドミウム活物質中に酸化銅（ＣｕＯ）が均一に分散しがたく、導電性が充分に向上しないことが明らかになった。このため、活物質利用率が十分に向上しないという問題を生じた。   However, in the cadmium negative electrode proposed in Patent Document 1 described above, since copper oxide (CuO) is a solid addition, copper oxide (CuO) is not easily dispersed uniformly in the cadmium active material. It became clear that the property was not improved sufficiently. For this reason, the problem that the active material utilization rate did not improve sufficiently occurred.

また、上述した特許文献２にて提案された方法においては、カドミウム負極を作製した後、銅塩溶液に浸漬し、陰電解を行った後、水洗・乾燥を行うという新たな複数の工程が増えることとなる。このため、工程数の増加に伴い、製造効率が低下するという新たな問題が生じた。また、上述した特許文献２にて提案された方法においては、銅塩溶液に浸漬する代わりに、活物質中に予め硫酸銅（ＣｕＳＯ4）粉末を混合して用いることも開示されている。
ところが、溶媒に水を用いた場合、硫酸銅（ＣｕＳＯ4）粉末を活物質となる酸化カドミウム（ＣｄＯ）に対して銅の質量換算で３質量％以上添加すると、ペースト混練時にペーストが固化し、ペースト混練工程やペーストの塗布工程でハンドリング性が悪化するという問題も生じた。 In addition, in the method proposed in Patent Document 2 described above, a new cadmium negative electrode is produced, and then immersed in a copper salt solution, subjected to negative electrolysis, and then subjected to a plurality of new steps of washing and drying. It will be. For this reason, the new problem that manufacturing efficiency fell with the increase in the number of processes occurred. Further, in the method proposed in Patent Document 2 described above, it is also disclosed that copper sulfate (CuSO 4 ) powder is mixed and used in advance in the active material instead of being immersed in a copper salt solution.
However, when water is used as the solvent, if the copper sulfate (CuSO 4 ) powder is added in an amount of 3% by mass or more in terms of the mass of copper with respect to cadmium oxide (CdO) as an active material, the paste is solidified during paste kneading, There was also a problem that handling properties deteriorated in the paste kneading process and the paste application process.

そこで、本発明においては上記の如き問題点を解決するためになされたものであって、新たな工程数を増やすことなく、活物質利用率が向上したアルカリ蓄電池用カドミウム負極を得ることができる製造方法を提供することを目的とするものである。   Therefore, in the present invention, it was made in order to solve the above-described problems, and a production capable of obtaining a cadmium negative electrode for an alkaline storage battery with an improved active material utilization rate without increasing the number of new processes. It is intended to provide a method.

本発明のアルカリ蓄電池用カドミウム負極の製造方法は、少なくとも酸化カドミウムを主体とするカドミウム活物質と有機高分子糊料とを含有する活物質ペーストを電極基板に塗布して形成するようにしている。そして、上記の如き目的を達成するため、予備充電活物質となる金属カドミウムと有機高分子糊料とを主体とするカドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を添加するピロリン酸銅添加工程と、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が添加されたカドミウム糊料と主活物質となる酸化カドミウム（ＣｄＯ）とを混練して活物質ペーストを調製する活物質ペースト調製工程と、活物質ペーストを導電性芯体からなる電極基板に塗布して活物質塗布層を形成する活物質塗布工程とを備えるようにしている。 In the method for producing a cadmium negative electrode for an alkaline storage battery of the present invention, an active material paste containing at least a cadmium active material mainly composed of cadmium oxide and an organic polymer paste is applied to an electrode substrate. In order to achieve the above object, pyrroline is obtained by adding copper pyrophosphate (Cu 2 P 2 O 7 ) to a cadmium paste mainly composed of metal cadmium as a precharge active material and an organic polymer paste. An active material paste preparation in which an active material paste is prepared by kneading an acid copper addition step, cadmium paste containing copper pyrophosphate (Cu 2 P 2 O 7 ) and cadmium oxide (CdO) as a main active material A process and an active material application step of applying an active material paste to an electrode substrate made of a conductive core to form an active material application layer.

ここで、カドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を添加すると、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）は糊料中に溶解されて極めて均一に分散することとなる。そして、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が均一に分散した糊料を主活物質となる酸化カドミウム（ＣｄＯ）に混合し、混練すると、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が均一に分散した活物質ペーストを得ることができる。この場合、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）として銅を添加すると、銅の質量換算で３質量％以上を添加しても、活物質ペーストの混練中にペーストの固化が起こらず、次工程でのハンドリング性を向上させることが可能となる。 Here, when copper pyrophosphate (Cu 2 P 2 O 7 ) is added to the cadmium paste, copper pyrophosphate (Cu 2 P 2 O 7 ) is dissolved in the paste and dispersed extremely uniformly. . Then, a paste in which copper pyrophosphate (Cu 2 P 2 O 7 ) is uniformly dispersed is mixed with cadmium oxide (CdO) as a main active material, and kneaded to obtain copper pyrophosphate (Cu 2 P 2 O 7 ). A uniformly dispersed active material paste can be obtained. In this case, when copper is added as copper pyrophosphate (Cu 2 P 2 O 7 ), the solidification of the paste does not occur during the kneading of the active material paste even when 3% by mass or more in terms of copper is added. It becomes possible to improve the handleability in the process.

そして、このようにして作製された活物質ペーストを導電性芯体からなる電極基板に塗布すると、活物質層中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が均一に分散したカドミウム負極を得ることが可能となる。これにより、電池組立後の充電の際に緻密な銅の導電性ネットワークを形成させることが可能となる。この結果、新たな工程を増加させることなく、活物質ペーストの混練中にペーストの固化が起こらず、かつ、次工程でのハンドリング性が良好で、活物質利用率が向上したカドミウム負極を得ることが可能となる。 When the active material paste thus prepared is applied to an electrode substrate made of a conductive core, a cadmium negative electrode in which copper pyrophosphate (Cu 2 P 2 O 7 ) is uniformly dispersed in the active material layer is obtained. It becomes possible. This makes it possible to form a dense copper conductive network during charging after battery assembly. As a result, it is possible to obtain a cadmium negative electrode in which the solidification of the paste does not occur during the kneading of the active material paste, the handling property in the next step is good, and the active material utilization rate is improved without increasing the number of new steps. Is possible.

本発明においては、活物質層中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が均一に分散したカドミウム負極を得ることができるので、電池組立後の充電の際に緻密な銅の導電性ネットワークを形成させることが可能となる。これにより、新たな工程を増加させることなく、活物質ペーストの混練中にペーストの固化が起こらず、かつ、次工程でのハンドリング性が良好で、活物質利用率が向上したカドミウム負極を提供することが可能となる。 In the present invention, since a cadmium negative electrode in which copper pyrophosphate (Cu 2 P 2 O 7 ) is uniformly dispersed in the active material layer can be obtained, a dense copper conductive network can be obtained at the time of charging after battery assembly. Can be formed. This provides a cadmium negative electrode in which paste solidification does not occur during the kneading of the active material paste without increasing new processes, the handling property in the next process is good, and the active material utilization rate is improved. It becomes possible.

ついで、本発明のアルカリ蓄電池用カドミウム負極の製造方法の一実施の形態を以下に説明するが、本発明は以下の実施の形態に何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能である。なお、図１は本発明のニッケル−カドミウム蓄電池を模式的に示す断面図である。   Next, an embodiment of a method for producing a cadmium negative electrode for an alkaline storage battery according to the present invention will be described below. However, the present invention is not limited to the following embodiment at all, and is appropriately within a range not changing the gist thereof. It is possible to change and implement. In addition, FIG. 1 is sectional drawing which shows typically the nickel-cadmium storage battery of this invention.

１．カドミウム活物質ペースト
（１）活物質ペーストａ
予備充電活物質となる金属カドミウム２０質量部と、有機高分子糊料（例えば、ヒドロキシプロピルセルロース、ポリビニルアルコールなど）１質量部と、ナイロン繊維１質量部と、水和防止剤としてリン酸水素二ナトリウム（Ｎａ2ＨＰＯ4）１質量部と、水３０質量部とからなるカドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を銅の質量換算で３質量部添加し、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）をカドミウム糊料中に溶解させた。この後、主活物質となる酸化カドミウム８０質量部に、上述したピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が溶解されたカドミウム糊料を混練して活物質ペーストを調製し、これを活物質ペーストａとした。 1. Cadmium active material paste (1) Active material paste a
20 parts by weight of metal cadmium serving as a precharge active material, 1 part by weight of an organic polymer paste (for example, hydroxypropylcellulose, polyvinyl alcohol, etc.), 1 part by weight of nylon fibers, and two hydrogen phosphates as an antihydration agent 3 parts by mass of copper pyrophosphate (Cu 2 P 2 O 7 ) in terms of copper mass was added to a cadmium paste consisting of 1 part by mass of sodium (Na 2 HPO 4 ) and 30 parts by mass of water, and copper pyrophosphate (Cu 2 P 2 O 7 ) was dissolved in the cadmium paste. Thereafter, an active material paste is prepared by kneading the above-described cadmium paste in which copper pyrophosphate (Cu 2 P 2 O 7 ) is dissolved in 80 parts by mass of cadmium oxide serving as a main active material. It was set as paste a.

（２）活物質ペーストｂ
予備充電活物質となる金属カドミウム２０質量部と、有機高分子糊料（例えば、ヒドロキシプロピルセルロース、ポリビニルアルコールなど）１質量部と、ナイロン繊維１質量部と、水和防止剤としてリン酸水素二ナトリウム（Ｎａ2ＨＰＯ4）１質量部と、水３０質量部とからなるカドミウム糊料を調製した。この後、主活物質となる酸化カドミウム８０質量部に、上述したカドミウム糊料を混練してカドミウム活物質ペーストを調製し、これを活物質ペーストｂとした。 (2) Active material paste b
20 parts by weight of metal cadmium serving as a precharge active material, 1 part by weight of an organic polymer paste (for example, hydroxypropylcellulose, polyvinyl alcohol, etc.), 1 part by weight of nylon fibers, and two hydrogen phosphates as an antihydration agent A cadmium paste comprising 1 part by mass of sodium (Na 2 HPO 4 ) and 30 parts by mass of water was prepared. Thereafter, the above-described cadmium paste was kneaded with 80 parts by mass of cadmium oxide serving as a main active material to prepare a cadmium active material paste, which was defined as an active material paste b.

（３）活物質ペーストｃ
予備充電活物質となる金属カドミウム２０質量部と、有機高分子糊料（例えば、ヒドロキシプロピルセルロース、ポリビニルアルコールなど）１質量部と、ナイロン繊維１質量部と、水和防止剤としてリン酸水素二ナトリウム（Ｎａ2ＨＰＯ4）１質量部と、水３０質量部とからなるカドミウム糊料を調製した。この後、主活物質となる酸化カドミウム８０質量部と、酸化銅（ＣｕＯ）を銅の質量換算で３質量部と、上述したカドミウム糊料を混練してカドミウム活物質ペーストを調製し、これを活物質ペーストｃとした。 (3) Active material paste c
20 parts by weight of metal cadmium serving as a precharge active material, 1 part by weight of an organic polymer paste (for example, hydroxypropylcellulose, polyvinyl alcohol, etc.), 1 part by weight of nylon fibers, and two hydrogen phosphates as an antihydration agent A cadmium paste comprising 1 part by mass of sodium (Na 2 HPO 4 ) and 30 parts by mass of water was prepared. Thereafter, 80 parts by mass of cadmium oxide serving as a main active material, 3 parts by mass of copper oxide (CuO) in terms of copper mass, and the above-described cadmium paste are mixed to prepare a cadmium active material paste. An active material paste c was obtained.

（４）活物質ペーストｄ
予備充電活物質となる金属カドミウム２０質量部と、有機高分子糊料（例えば、ヒドロキシプロピルセルロース、ポリビニルアルコールなど）１質量部と、ナイロン繊維１質量部と、水和防止剤としてリン酸水素二ナトリウム（Ｎａ2ＨＰＯ4）１質量部と、水３０質量部とからなるカドミウム糊料中に硫酸銅（ＣｕＳＯ4）を銅の質量換算で３質量部添加し、硫酸銅（ＣｕＳＯ4）をカドミウム糊料中に溶解させた。この後、主活物質となる酸化カドミウム８０質量部に、上述した硫酸銅（ＣｕＳＯ4）が溶解されたカドミウム糊料を混練してカドミウム活物質ペーストを調製し、これを活物質ペーストｄとした。 (4) Active material paste d
20 parts by weight of metal cadmium serving as a precharge active material, 1 part by weight of an organic polymer paste (for example, hydroxypropylcellulose, polyvinyl alcohol, etc.), 1 part by weight of nylon fibers, and two hydrogen phosphates as an antihydration agent cadmium and sodium (Na 2 HPO 4) 1 part by weight, copper sulfate in cadmium pastes consisting of water 30 parts by mass (CuSO 4) were added 3 parts by weight in terms of copper, copper sulfate (CuSO 4) Dissolved in the paste. Thereafter, cadmium paste in which copper sulfate (CuSO 4 ) is dissolved in 80 parts by mass of cadmium oxide as a main active material is kneaded to prepare a cadmium active material paste, which is defined as an active material paste d. .

（５）活物質ペーストｅ
予備充電活物質となる金属カドミウム２０質量部と、有機高分子糊料（例えば、ヒドロキシプロピルセルロース、ポリビニルアルコールなど）１質量部と、ナイロン繊維１質量部と、水和防止剤としてリン酸水素二ナトリウム（Ｎａ2ＨＰＯ4）１質量部と、水３０質量部とからなるカドミウム糊料中に酢酸銅（Ｃｕ（ＣＨ3ＣＯＯ）2）を銅の質量換算で３質量部添加し、酢酸銅（Ｃｕ（ＣＨ3ＣＯＯ）2）をカドミウム糊料中に溶解させた。この後、主活物質となる酸化カドミウム８０質量部に、上述した酢酸銅（Ｃｕ（ＣＨ3ＣＯＯ）2）が溶解されたカドミウム糊料を混練してカドミウム活物質ペーストを調製し、これを活物質ペーストｅとした。 (5) Active material paste e
20 parts by weight of metal cadmium serving as a precharge active material, 1 part by weight of an organic polymer paste (for example, hydroxypropylcellulose, polyvinyl alcohol, etc.), 1 part by weight of nylon fiber, and two hydrogen phosphates as an antihydration agent 3 parts by mass of copper acetate (Cu (CH 3 COO) 2 ) in terms of copper mass is added to a cadmium paste consisting of 1 part by mass of sodium (Na 2 HPO 4 ) and 30 parts by mass of water. Cu (CH 3 COO) 2 ) was dissolved in the cadmium paste. Thereafter, cadmium paste in which copper acetate (Cu (CH 3 COO) 2 ) is dissolved in 80 parts by mass of cadmium oxide as a main active material is kneaded to prepare a cadmium active material paste. Material paste e was designated.

（６）活物質ペーストの粘度の測定
ついで、得られた活物質ペーストａ〜ｅの粘度（Ｐａ・ｓ）の測定を行うと、下記の表１に示すような結果が得られた。なお、下記の表１において、測定不能は粘度が８００Ｐａ・ｓ以上で、活物質ペーストが固化していることを示している。

Figure 2009187886
(6) Measurement of Viscosity of Active Material Paste Next, when the viscosity (Pa · s) of the obtained active material pastes a to e was measured, the results shown in Table 1 below were obtained. In Table 1 below, measurement failure indicates that the viscosity is 800 Pa · s or more and the active material paste is solidified.
Figure 2009187886

上記表１の結果から明らかなように、カドミウム糊料中に硫酸銅（ＣｕＳＯ4）を添加した活物質ペーストｄ、およびカドミウム糊料中に酢酸銅（Ｃｕ（ＣＨ3ＣＯＯ）2）を添加した活物質ペーストｅは、ペースト粘度が８００Ｐａ・ｓ以上（測定不能）で、固化していることが分かった。 As is clear from the results in Table 1 above, active material paste d in which copper sulfate (CuSO 4 ) is added to cadmium paste, and copper acetate (Cu (CH 3 COO) 2 ) is added to cadmium paste. The active material paste e was found to have a paste viscosity of 800 Pa · s or higher (impossible to be measured) and solidified.

一方、カドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を添加した活物質ペーストａにおいては、ペースト粘度が３００Ｐａ・ｓで、混練および芯体への塗布工程でのハンドリング性に問題のないペースト性状であることが分かった。また、銅化合物が無添加の活物質ペーストｂ、およびカドミウム糊料中ではなく、活物質ペースト中に酸化銅（ＣｕＯ）の粉末を添加した活物質ペーストｃについても、ペースト粘度がそれぞれ２２０Ｐａ・ｓおよび２５０Ｐａ・ｓで、混練および芯体への塗布工程でのハンドリング性に問題のないペースト性状であることが分かった。 On the other hand, in the active material paste a in which copper pyrophosphate (Cu 2 P 2 O 7 ) is added to the cadmium paste, the paste viscosity is 300 Pa · s, and there is a problem in handling properties in the kneading and coating process to the core. The paste was found to have no paste. Also, the active material paste b to which the copper compound is not added and the active material paste c in which the copper oxide (CuO) powder is added to the active material paste, not the cadmium paste, have a paste viscosity of 220 Pa · s, respectively. And 250 Pa · s, it was found that the paste properties had no problem in handling properties in the kneading and coating process on the core.

２．カドミウム負極
そこで、混練および芯体への塗布工程でのハンドリング性に問題のないペースト性状である活物質ペーストａ，ｂ，ｃを用いて、以下のようにしてカドミウム負極Ａ，Ｂ，Ｃをそれぞれ作製した。この場合、まず、パンチングメタルよりなる導電性芯体（電極基板）１１ａを用意する。そして、この導電性芯体（電極基板）１１ａの両面に活物質ペーストａ，ｂ，ｃをそれぞれ塗布した後、乾燥させて導電性芯体（電極基板）１１ａの両面に活物質層１１ｂを形成させた。その後、所定の厚みに圧延し、所定の寸法になるように切断して、カドミウム負極Ａ，Ｂ，Ｃをそれぞれ作製した。なお、活物質ペーストａを用いたものをカドミウム負極Ａとし、活物質ペーストｂを用いたものをカドミウム負極Ｂとし、活物質ペーストｃを用いたものをカドミウム負極Ｃとした。 2. Cadmium negative electrode Therefore, cadmium negative electrodes A, B, and C were respectively formed as follows using the active material pastes a, b, and c having paste properties with no problem in handling properties in the kneading and coating processes on the core. Produced. In this case, first, a conductive core (electrode substrate) 11a made of punching metal is prepared. Then, the active material pastes a, b, and c are respectively applied to both surfaces of the conductive core (electrode substrate) 11a and then dried to form the active material layers 11b on both surfaces of the conductive core (electrode substrate) 11a. I let you. Then, it rolled to the predetermined thickness and cut | disconnected so that it might become a predetermined dimension, and produced the cadmium negative electrodes A, B, and C, respectively. In addition, the thing using the active material paste a was used as the cadmium negative electrode A, the one using the active material paste b was used as the cadmium negative electrode B, and the one using the active material paste c was used as the cadmium negative electrode C.

３．ニッケル−カドミウム蓄電池簡易セル
ついで、上述のようにして作製したカドミウム負極Ａ，Ｂ，Ｃを用いて、以下のようにしてニッケル−カドミウム蓄電池簡易セルを作製した。この場合、上述したカドミウム負極Ａ，Ｂ，Ｃの表面積に対して十分大きな表面積を有するニッケル正極を用い、これらのカドミウム負極Ａ，Ｂ，Ｃとニッケル正極とがそれぞれ対向するように、各簡易セル容器内にカドミウム負極Ａ，Ｂ，Ｃとニッケル正極とを配設した。そして、これらの各簡易セル容器内に比重が１．２の水酸化カリウム（ＫＯＨ）水溶液を注液してニッケル−カドミウム蓄電池簡易セルをそれぞれ作製した。 3. Nickel-cadmium battery simple cell Next, using the cadmium negative electrodes A, B, and C produced as described above, a nickel-cadmium battery simple cell was produced as follows. In this case, a nickel positive electrode having a sufficiently large surface area relative to the surface area of the cadmium negative electrodes A, B, and C described above is used, and each simple cell is arranged such that these cadmium negative electrodes A, B, C and the nickel positive electrode face each other. Cadmium negative electrodes A, B and C and a nickel positive electrode were disposed in the container. Then, a potassium hydroxide (KOH) aqueous solution having a specific gravity of 1.2 was injected into each of these simple cell containers to prepare nickel-cadmium storage battery simple cells.

ついで、上述のように作製した各ニッケル−カドミウム蓄電池簡易セルを用いて、２５℃の温度雰囲気で、０．３Ｉｔの充電々流で１６時間充電した後、２／３Ｉｔの放電々流で簡易セルの電圧が０．８Ｖになるまで放電させた。そして、このときの放電時間から各簡易セルの放電容量（Ｗ２）を求めた。ついで、各カドミウム負極Ａ，Ｂ，Ｃの理論容量（Ｗ１）に対する得られた放電容量（Ｗ２）の比率を活物質利用率Ｗ（％）（Ｗ＝（Ｗ２／Ｗ１）×１００）として求めると、下記の表２に示すような結果となった。

Figure 2009187886
Next, using each nickel-cadmium storage battery simple cell produced as described above, charging was performed for 16 hours with a charging current of 0.3 It in a temperature atmosphere of 25 ° C., and then a simple cell with a discharging current of 2/3 It. The battery was discharged until the voltage became 0.8V. And the discharge capacity (W2) of each simple cell was calculated | required from the discharge time at this time. Then, when the ratio of the obtained discharge capacity (W2) to the theoretical capacity (W1) of each cadmium negative electrode A, B, C is determined as an active material utilization rate W (%) (W = (W2 / W1) × 100). The results shown in Table 2 below were obtained.
Figure 2009187886

上記表２の結果から以下のことが明らかになった。即ち、ピロリン酸銅の溶解や酸化銅添加の無いカドミウム負極Ｂを用いたセルの活物質利用率は７１．９％と低いことが分かる。これに対して、活物質ペースト中に酸化銅（ＣｕＯ）の粉末を添加した活物質ペーストｃにより形成されたカドミウム負極Ｃを用いたセルの活物質利用率は７７．３％で、無添加のカドミウム負極Ｂを用いたセルよりも向上していることが分かる。
さらに、カドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を添加して調製された活物質ペーストａにより形成されたカドミウム負極Ａを用いたセルの活物質利用率は７９．７％で、酸化銅（ＣｕＯ）の粉末を添加した活物質ペーストｃにより形成されたカドミウム負極Ｃを用いたセルよりもさらに向上していることが分かる。 From the results in Table 2 above, the following became clear. That is, it can be seen that the active material utilization rate of the cell using the cadmium negative electrode B without dissolution of copper pyrophosphate and addition of copper oxide is as low as 71.9%. On the other hand, the active material utilization rate of the cell using the cadmium negative electrode C formed by the active material paste c in which the copper oxide (CuO) powder was added to the active material paste was 77.3%, which was not added. It turns out that it is improving rather than the cell using the cadmium negative electrode B. FIG.
Furthermore, the active material utilization rate of the cell using the cadmium negative electrode A formed by the active material paste a prepared by adding copper pyrophosphate (Cu 2 P 2 O 7 ) to the cadmium paste is 79.7%. Thus, it can be seen that the cell is further improved than the cell using the cadmium negative electrode C formed of the active material paste c to which the copper oxide (CuO) powder is added.

これは、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）の溶解や酸化銅（ＣｕＯ）の添加が無いことにより、カドミウム負極Ｂ中での導電性が劣るために、活物質利用率が低下したと考えられる。一方、活物質ペースト中に酸化銅（ＣｕＯ）の粉末を添加することにより、カドミウム負極Ｃ中での導電性は多少は改善されるが、酸化銅（ＣｕＯ）は固形添加であるため、カドミウム負極Ｃの活物質層中に均一に分散しがたく、導電性が充分に向上しないために活物質利用率が十分に向上しなかったと考えられる。 This is because the conductivity in the cadmium negative electrode B is inferior due to the lack of dissolution of copper pyrophosphate (Cu 2 P 2 O 7 ) and the addition of copper oxide (CuO), resulting in a decrease in active material utilization. Conceivable. On the other hand, by adding copper oxide (CuO) powder to the active material paste, the conductivity in the cadmium negative electrode C is somewhat improved, but since copper oxide (CuO) is a solid addition, the cadmium negative electrode It is considered that the active material utilization rate was not sufficiently improved because it was difficult to uniformly disperse in the C active material layer and the conductivity was not sufficiently improved.

これらに対して、カドミウム負極Ａは、カドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を添加、溶解させて、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を糊料中に極めて均一に分散させた後、主活物質となる酸化カドミウム（ＣｄＯ）に混合し、混練して活物質ペーストとしている。そして、ピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が均一に分散した活物質ペーストを導電性芯体に塗布しているので、カドミウム負極Ａの活物質層中にはピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）が均一に分散して存在することとなる。これにより、電池組立後の充電の際に緻密な銅の導電性ネットワークを形成させることが可能となり、活物質利用率が十分に向上したと考えられる。 On the other hand, the cadmium negative electrode A is obtained by adding and dissolving copper pyrophosphate (Cu 2 P 2 O 7 ) in the cadmium paste and dissolving the copper pyrophosphate (Cu 2 P 2 O 7 ) in the paste. After being uniformly dispersed, it is mixed with cadmium oxide (CdO) as a main active material and kneaded to obtain an active material paste. Since copper pyrophosphate (Cu 2 P 2 O 7) is coated with a uniformly dispersed active material paste to the conductive core, the active material layer of the cadmium negative electrode A copper pyrophosphate (Cu 2 P 2 O 7 ) is present in a uniformly dispersed state. Thereby, it is possible to form a dense copper conductive network during charging after battery assembly, and the active material utilization rate is considered to be sufficiently improved.

４．ニッケル−カドミウム蓄電池
ついで、上述したカドミウム負極１１を用いて、本発明に係るニッケル−カドミウム蓄電池１０を作製する例について、図１に基づき、以下に説明する。
まず、発泡ニッケルからなる電極基板１２ａに水酸化ニッケルを主体とする正極活物質と結着剤とからなる正極活物質スラリー１２ｂを充填する。ついで、乾燥後、所定の厚みになるまで圧延し、所定の寸法になるように切断して、ニッケル正極１２を作製する。この場合、このニッケル正極１２の電極基板１２ａの上端部には活物質が充填されていない活物質の未充填部１２ｃが形成されるようにする。 4). Nickel-cadmium storage battery Next, an example of producing the nickel-cadmium storage battery 10 according to the present invention using the above-described cadmium negative electrode 11 will be described with reference to FIG.
First, an electrode substrate 12a made of foamed nickel is filled with a positive electrode active material slurry 12b made of a positive electrode active material mainly composed of nickel hydroxide and a binder. Next, after drying, it is rolled to a predetermined thickness and cut to a predetermined dimension to produce a nickel positive electrode 12. In this case, an active material unfilled portion 12 c that is not filled with an active material is formed at the upper end portion of the electrode substrate 12 a of the nickel positive electrode 12.

ついで、例えばナイロン製であるセパレータ１３を用意し、このセパレータ１３を上述のように作製されるカドミウム負極１１の両面に配置するとともに、このセパレータ１３の上にニッケル正極１２を配置して帯状積層体とする。この場合、セパレータ１３の上にニッケル正極１２を配置するに際しては、ニッケル正極１２の活物質の未充填部１２ｃの下端部がセパレータ１３の上端部に位置するように配置する。一方、セパレータ１３の上にカドミウム負極１１を配置するに際しては、カドミウム負極１１の上端部から若干パレータ１３の上端が突出するとともに、カドミウム負極１１の下端部から所定の長さだけセパレータ１３の下端が突出するように配置する。   Next, a separator 13 made of nylon, for example, is prepared, and the separator 13 is arranged on both surfaces of the cadmium negative electrode 11 produced as described above, and the nickel positive electrode 12 is arranged on the separator 13 to form a belt-like laminate. And In this case, when the nickel positive electrode 12 is arranged on the separator 13, the nickel positive electrode 12 is arranged so that the lower end portion of the unfilled portion 12 c of the nickel positive electrode 12 is positioned at the upper end portion of the separator 13. On the other hand, when the cadmium negative electrode 11 is disposed on the separator 13, the upper end of the pallet 13 slightly protrudes from the upper end portion of the cadmium negative electrode 11, and the lower end of the separator 13 extends from the lower end portion of the cadmium negative electrode 11 by a predetermined length. Arrange so that it protrudes.

ついで、上述のような配置関係となった帯状積層体を渦巻状に巻回して渦巻状電極群を形成する。ついで、渦巻状電極群の活物質の未塗布部１１ｃの下に負極集電体１４を配置して、この負極集電体１４と活物質の未塗布部１１ｃとを抵抗溶接する。また、渦巻状電極群の上に正極集電体１５を配置して、この正極集電体１５と未充填部１２ｃとを抵抗溶接して、電極体を形成する。なお、正極集電体１５には、この正極集電体１５より延出してリード部１５ａが形成されている。ついで、上述のようにして作製された電極体を外装缶１６内に挿入した後、負極集電体１４と外装缶１６の底部とを溶接する。   Subsequently, the strip-shaped laminate having the above-described arrangement relation is spirally wound to form a spiral electrode group. Next, the negative electrode current collector 14 is arranged under the active material uncoated portion 11c of the spiral electrode group, and the negative electrode current collector 14 and the active material uncoated portion 11c are resistance-welded. Further, the positive electrode current collector 15 is disposed on the spiral electrode group, and the positive electrode current collector 15 and the unfilled portion 12c are resistance-welded to form an electrode body. The positive electrode current collector 15 has a lead portion 15 a extending from the positive electrode current collector 15. Next, after the electrode body produced as described above is inserted into the outer can 16, the negative electrode current collector 14 and the bottom of the outer can 16 are welded.

また、正極蓋１７ａと正極キャップ１７ｂとからなる封口体１７を用意し、正極集電体１５から延出するリード部１５ａを封口体１７に設けられた正極蓋１７ａの底部に溶接する。ついで、外装缶１６の上部外周面に溝入れ加工を施して環状溝部１６ａを形成する。この後、金属製外装缶１６内に電解液（例えば、３０質量％の水酸化カリウム（ＫＯＨ）水溶液）を注液し、封口体１７の外周部に装着された封口ガスケット１８を外装缶１６の環状溝部１６ａの上に載置するとともに、外装缶１６の先端部１６ｂを封口体１７側にかしめて封口することにより、ニッケル−カドミウム蓄電池１０を組み立てることができる。   In addition, a sealing body 17 including a positive electrode lid 17 a and a positive electrode cap 17 b is prepared, and a lead portion 15 a extending from the positive electrode current collector 15 is welded to the bottom of the positive electrode lid 17 a provided on the sealing body 17. Next, grooving is performed on the upper outer peripheral surface of the outer can 16 to form an annular groove 16a. Thereafter, an electrolytic solution (for example, 30 mass% potassium hydroxide (KOH) aqueous solution) is injected into the metal outer can 16, and the sealing gasket 18 attached to the outer peripheral portion of the sealing body 17 is attached to the outer can 16. The nickel-cadmium storage battery 10 can be assembled by placing it on the annular groove 16a and sealing the tip 16b of the outer can 16 by sealing it toward the sealing body 17 side.

上述したように、本発明においては予備充電活物質である金属カドミウムと有機高分子糊料を主体とするカドミウム糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を添加し、溶解させて、糊料中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を均一に分散化させた後、主活物質である酸化カドミウムと混合して活物質ペーストを調製するようにしている。そして、このように調製された活物質ペーストを導電芯体に塗布して活物質層を形成するようにしているので、活物質層中にピロリン酸銅（Ｃｕ2Ｐ2Ｏ7）を均一に分散させたカドミウム負極を作製することが可能となる。これにより、電池組立後の充電の際に緻密な銅の導電性ネットワークを形成させることができ、新たな工程数を増やすことなく、かつ、活物質ペースト混練中にペーストの固化が起らず、ハンドリング性が良好で、活物質利用率が向上したアルカリ蓄電池用カドミウム負極を得ることができる。 As described above, in the present invention, copper pyrophosphate (Cu 2 P 2 O 7 ) is added and dissolved in a cadmium paste mainly composed of metal cadmium which is a precharge active material and an organic polymer paste. In addition, copper pyrophosphate (Cu 2 P 2 O 7 ) is uniformly dispersed in the paste, and then mixed with cadmium oxide as a main active material to prepare an active material paste. Since the active material paste thus prepared is applied to the conductive core to form an active material layer, copper pyrophosphate (Cu 2 P 2 O 7 ) is uniformly distributed in the active material layer. A dispersed cadmium negative electrode can be produced. Thereby, it is possible to form a dense copper conductive network during charging after battery assembly, without increasing the number of new steps, and without solidifying the paste during active material paste kneading, A cadmium negative electrode for an alkaline storage battery having good handling properties and improved active material utilization can be obtained.

本発明のニッケル−カドミウム蓄電池を模式的に示す断面図である。It is sectional drawing which shows typically the nickel-cadmium storage battery of this invention.

符号の説明Explanation of symbols

１１…カドミウム負極、１１ａ…基板、１１ｂ…負極活物質、１１ｃ…活物質未充填部、１２…ニッケル正極、１２ａ…基板、１２ｂ…正極活物質、１２ｃ…活物質未充填部、１３…セパレータ、１４…負極集電体、１５…正極集電体、１５ａ…リード部、１６…外装缶、１６ａ…環状溝部、１６ｂ…先端部、１７…封口体、１７ａ…正極蓋、１７ｂ…正極キャップ、１８…封口ガスケット DESCRIPTION OF SYMBOLS 11 ... Cadmium negative electrode, 11a ... Substrate, 11b ... Negative electrode active material, 11c ... Active material unfilled part, 12 ... Nickel positive electrode, 12a ... Substrate, 12b ... Positive electrode active material, 12c ... Active material unfilled part, 13 ... Separator, DESCRIPTION OF SYMBOLS 14 ... Negative electrode collector, 15 ... Positive electrode collector, 15a ... Lead part, 16 ... Exterior can, 16a ... Annular groove part, 16b ... Tip part, 17 ... Sealing body, 17a ... Positive electrode cover, 17b ... Positive electrode cap, 18 ... Sealing gasket

Claims (1)

少なくとも酸化カドミウムを主体とするカドミウム活物質と有機高分子糊料とを含有する活物質ペーストを電極基板に塗布して形成するアルカリ蓄電池用カドミウム負極の製造方法であって、
予備充電活物質となる金属カドミウムと有機高分子糊料とを主体とするカドミウム糊料中にピロリン酸銅を添加するピロリン酸銅添加工程と、
前記ピロリン酸銅が添加されたカドミウム糊料と主活物質となる酸化カドミウムとを混練して活物質ペーストを調製する活物質ペースト調製工程と、
前記活物質ペーストを導電性芯体からなる電極基板に塗布して活物質塗布層を形成する活物質塗布工程とを備えたことを特徴とするアルカリ蓄電池用カドミウム負極の製造方法。 A method for producing a cadmium negative electrode for an alkaline storage battery, comprising forming an active material paste containing at least a cadmium active material mainly composed of cadmium oxide and an organic polymer paste on an electrode substrate,
A copper pyrophosphate addition step of adding copper pyrophosphate into a cadmium paste mainly composed of a metal cadmium serving as a precharge active material and an organic polymer paste;
An active material paste preparation step of preparing an active material paste by kneading the cadmium paste added with the copper pyrophosphate and cadmium oxide as a main active material;
A method for producing a cadmium negative electrode for an alkaline storage battery, comprising: an active material application step of applying the active material paste to an electrode substrate made of a conductive core to form an active material application layer.
JP2008029040A 2008-02-08 2008-02-08 Method of manufacturing cadmium negative electrode of alkaline storage battery Withdrawn JP2009187886A (en)

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