JPH08227715A - Manufacture of nickel sintered base body - Google Patents

Abstract

PURPOSE: To provide a manufacturing process of a nickel sintered substrate base body with high porosity and capable of suppressing corrosion in an impregnation process. CONSTITUTION: A pore increasing agent is dispersed in hexane together with copper sulfate and a surfactant, then vacuum distillation is conducted to remove hexane, and the mixture is dried in an nitrogen atmosphere to obtain the pore increasing agent on which copper sulfate is attached. The pore increasing agent obtained is kneaded with nickel powder and a methylcellulose aqueous solution to prepare slurry, and the slurry is applied to a perforated plate, then they are sintered in a hydrogen atmosphere to prepare a nickel sintered substrate 2 covered with an acid-resistant metal 1.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、アルカリ蓄電池に用い
られるニッケル焼結基体の製造法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a nickel sintered substrate used in an alkaline storage battery.

【０００２】[0002]

【従来の技術】一般に急速充放電用アルカリ蓄電池の正
極としては、内部抵抗が小さくサイクル特性に優れた、
焼結式ニッケル電極が用いられる。この焼結式電極は、
まず、ニッケル粉末に増粘剤、および分散媒を含むスラ
リを導電性芯体の両面に塗布し、乾燥後、還元性雰囲気
下で７００〜１０００℃の高温で焼成し、多孔質のニッ
ケル焼結基体を作製する。次に、当該基体を硝酸ニッケ
ル溶液に浸漬し、次いでアルカリ溶液中に浸漬し水酸化
ニッケル（活物質）を形成させるという充填操作を数回
繰り返すことによって製造する。充填操作を数回繰り返
す理由は、１回の充填操作では充分な活物質量を充填で
きないためである。製造工程上、前記充填操作を繰り返
す回数は少ないほど好ましい。そのためには、硝酸ニッ
ケル溶液を高濃度にし、１回の充填操作で充填できる活
物質量を増やせばよいことが知られている。硝酸ニッケ
ル溶液を高濃度にするには、硝酸ニッケル溶液を高温に
すればよく、比重１．７〜１．８までにすることができ
る。しかし、そのような高濃度の硝酸ニッケル溶液は、
ｐＨが低く、さらに高温であるため、これに浸漬したニ
ッケル焼結基体は腐蝕を受け、その結果機械的強度が劣
化する。そのような正極を用いて電池を形成し、充放電
を繰り返すと、充放電反応は活物質の膨張、収縮を伴う
ものであるため活物質の脱落を引き起こし、寿命性能が
低下するという問題を生ずる。そこで特開昭５９−７８
４５７号公報では、硝酸塩の含浸の前に焼結基体表面を
高温の大気雰囲気下で酸化し、比較的耐酸性を有する酸
化ニッケル被膜を形成させるという防蝕技術を提案して
いる。また、近年、電池の高エネルギー密度化が要望さ
れ、そのために高多孔度の焼結基体を用いる必要性が生
じてきた。焼結基体は、高多孔度化するほど機械的強度
が低下する。また、腐蝕の影響も受けやすい。そこで特
開平４−２４８２６９号公報では、表面にニッケル粉末
を付着させた増孔剤を焼結基体を作製する際に用いるス
ラリに混入することにより、高多孔度と機械的強度を兼
ね備える技術を提案している。2. Description of the Related Art Generally, as a positive electrode of an alkaline storage battery for rapid charging / discharging, the internal resistance is small and the cycle characteristics are excellent.
A sintered nickel electrode is used. This sintered electrode is
First, a slurry containing a thickener and a dispersion medium is applied to nickel powder on both sides of a conductive core, dried, and then fired at a high temperature of 700 to 1000 ° C. in a reducing atmosphere to obtain porous nickel sintered body. Make a substrate. Next, the substrate is manufactured by repeating the filling operation of dipping the substrate in a nickel nitrate solution and then in an alkaline solution to form nickel hydroxide (active material) several times. The reason why the filling operation is repeated several times is that a sufficient amount of the active material cannot be filled with one filling operation. In the manufacturing process, the smaller the number of times of repeating the filling operation, the more preferable. For that purpose, it is known that the concentration of the nickel nitrate solution is made high and the amount of the active material which can be filled by one filling operation is increased. To increase the concentration of the nickel nitrate solution, the temperature of the nickel nitrate solution may be raised to a specific gravity of 1.7 to 1.8. However, such a high concentration nickel nitrate solution is
Due to the low pH and the high temperature, the nickel-sintered substrate immersed in it is corroded, resulting in a deterioration of its mechanical strength. When a battery is formed using such a positive electrode and charging and discharging are repeated, the charging and discharging reactions accompany the expansion and contraction of the active material, causing the active material to fall off, resulting in a problem of reduced life performance. . Then, JP-A-59-78
Japanese Patent No. 457 proposes a corrosion protection technique in which the surface of the sintered substrate is oxidized in a high-temperature atmosphere before impregnation with nitrate to form a nickel oxide film having relatively acid resistance. In addition, in recent years, there has been a demand for higher energy density of batteries, and for this reason, it has become necessary to use a sintered substrate having high porosity. The mechanical strength of the sintered substrate decreases as the porosity increases. It is also susceptible to corrosion. Therefore, Japanese Patent Laid-Open No. 4-248269 proposes a technique having both high porosity and mechanical strength by mixing a pore-forming agent having nickel powder adhered to the surface thereof into a slurry used for producing a sintered substrate. are doing.

【０００３】[0003]

【発明が解決しようとする課題】上記特開昭５９−７８
４５７号公報で提案されている防蝕技術では、焼結基体
全域に亘り均一に酸化ニッケル被膜を形成させることは
困難である。そこで十分な効果を得ようとして単純に酸
化ニッケル量を増やすと、焼結基体と活物質との間の導
電性が低下してしまう。また、特開平４−２４８２６９
号公報で提案されている技術では、高多孔度焼結基体を
得ることができるが、含浸工程時の焼結基体の腐蝕を抑
さえることはできない。本発明の目的は、高多孔度で、
しかも含浸工程時の腐蝕を抑制できるニッケル焼結基体
の製造法を提供することである。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
It is difficult to form a nickel oxide film uniformly over the entire area of the sintered substrate by the corrosion prevention technique proposed in Japanese Patent No. 457. Therefore, if the amount of nickel oxide is simply increased in order to obtain a sufficient effect, the conductivity between the sintered substrate and the active material will decrease. In addition, JP-A-4-248269
The technique proposed in the publication can obtain a highly porous sintered substrate, but cannot suppress corrosion of the sintered substrate during the impregnation step. The object of the present invention is high porosity,
Moreover, it is an object of the present invention to provide a method for manufacturing a nickel sintered substrate which can suppress corrosion during the impregnation step.

【０００４】[0004]

【課題を解決するための手段】上記問題を解決するため
に、本発明に係るニッケル焼結基体の製造法は、ニッケ
ル粉末、増粘剤、分散媒からなるスラリを穿孔板に塗着
して乾燥し、その後還元性、あるいは非酸化性雰囲気中
で焼成する方法において、前記スラリに、耐酸性の金属
あるいはその化合物を付着させた増孔剤を添加すること
を特徴とする。In order to solve the above problems, in the method for producing a nickel sintered substrate according to the present invention, a perforated plate is coated with a slurry comprising nickel powder, a thickener and a dispersion medium. In the method of drying and then firing in a reducing or non-oxidizing atmosphere, a pore-forming agent having an acid-resistant metal or its compound attached thereto is added to the slurry.

【０００５】[0005]

【作用】増孔剤は、焼成の過程で膨張しながら消失し、
ニッケル焼結基体を高多孔度化するのに寄与している。
増孔剤表面に付着していた耐酸性の金属は増孔剤消失後
もそのまま残り、ニッケル焼結基体全域をほぼ均一に被
覆する。また、増孔剤表面に付着しているのが耐酸性の
金属化合物であるときには、前記化合物が焼成の過程で
耐酸性の金属に還元され、同様にニッケル焼結基体全域
をほぼ均一に被覆する。ニッケル焼結基体全域を均一に
被覆した耐酸性の金属は、後工程においてニッケル焼結
基体がニッケル硝酸塩により腐蝕されるのを抑制する。
上記耐酸性の金属とは、ニッケルよりもイオン化傾向の
低い金属が考えられる。例えばそれらはCuやTi等であ
る。また、前記耐酸性の金属の化合物とは、例えばCuや
Tiの場合、硫酸銅、塩化チタン等である。焼結基体表面
を被覆した耐酸性の金属は、特開昭５９−７８４５７号
公報で提案されている酸化ニッケルとは異なり、導電性
に優れているため、焼結基体と活物質の電気的導通を阻
害することはない。[Function] The pore enhancer disappears while expanding during the firing process,
This contributes to increase the porosity of the nickel sintered substrate.
The acid-resistant metal attached to the surface of the pore-forming agent remains as it is even after the pore-forming agent disappears, and covers the entire area of the nickel sintered substrate almost uniformly. Further, when an acid-resistant metal compound is attached to the surface of the pore forming agent, the compound is reduced to an acid-resistant metal in the process of firing, and similarly, the whole area of the nickel sintered substrate is covered almost uniformly. . The acid-resistant metal that uniformly coats the entire area of the nickel sintered substrate suppresses corrosion of the nickel sintered substrate by nickel nitrate in a later step.
The acid-resistant metal is considered to be a metal having a lower ionization tendency than nickel. For example, they are Cu, Ti, etc. The acid-resistant metal compound is, for example, Cu or
Examples of Ti include copper sulfate and titanium chloride. Unlike the nickel oxide proposed in Japanese Patent Laid-Open No. 59-78457, the acid-resistant metal coated on the surface of the sintered substrate has excellent conductivity, so that electrical conductivity between the sintered substrate and the active material is established. Does not interfere with.

【０００６】[0006]

【実施例】本発明の実施例を以下に説明する。 （実施例１ 焼結基体Ａの製造法）増孔剤には、有機高
分子中空体であるポリアクリロニトリル（粒径２０〜３
０μｍ、松本油脂製F-50E）を用いた。これを硫酸銅と
界面活性剤（トリブチルリン酸）とともにヘキサン中に
分散させた後、減圧蒸留してヘキサンを除去した。さら
にこれを窒素雰囲気中で乾燥させることで表面に硫酸銅
が付着した増孔剤が得られた。これを６５ｇと、インコ
社製ニッケル粉末（＃２５５）５００ｇ、３．０ｗｔ％
のメチルセルロース水溶液６００ｇを混練してスラリ状
とし、鋼板にニッケル鍍金を施した穿孔板に塗着した。
その後それを水素雰囲気中９００℃で１０分間焼成し、
焼結基体Ａを作製した。EXAMPLES Examples of the present invention will be described below. Example 1 Manufacturing Method of Sintered Substrate A As the pore-forming agent, polyacrylonitrile (particle size 20 to 3) which is an organic polymer hollow body is used.
0 μm, F-50E manufactured by Matsumoto Yushi Co., Ltd.) was used. This was dispersed in hexane together with copper sulfate and a surfactant (tributylphosphoric acid), and then distilled under reduced pressure to remove hexane. Further, by drying this in a nitrogen atmosphere, a pore-forming agent having copper sulfate attached to the surface was obtained. 65g of this, Inco nickel powder (# 255) 500g, 3.0wt%
600 g of the aqueous solution of methyl cellulose was kneaded to form a slurry, which was applied to a perforated plate obtained by plating a steel plate with nickel.
After that, it was baked in a hydrogen atmosphere at 900 ° C. for 10 minutes,
A sintered base A was produced.

【０００７】（実施例２ 焼結基体Ｂの製造法）硫酸銅
の代わりに塩化チタンを用いる以外は実施例１と同条件
で焼結基体Ｂを作製した。Example 2 Manufacturing Method of Sintered Substrate B A sintered substrate B was produced under the same conditions as in Example 1 except that titanium chloride was used instead of copper sulfate.

【０００８】（従来例１ 焼結基体Ｃの製造法）実施例
に用いたポリアクリロニトリルをそのまま用いる以外は
実施例１と同条件で焼結基体Ｃを作製した。(Conventional Example 1 Manufacturing Method of Sintered Substrate C) A sintered substrate C was prepared under the same conditions as in Example 1 except that the polyacrylonitrile used in the examples was used as it was.

【０００９】（従来例２ 焼結基体Ｄの製造法）上記焼
結基体Ｃを窒素：酸素＝１：１の混合ガス中で５００
℃、５分間焼成し、焼結基体Ｄを作製した。(Conventional Example 2 Manufacturing Method of Sintered Substrate D) The above-mentioned sintered substrate C is subjected to 500 in a mixed gas of nitrogen: oxygen = 1: 1.
Firing at 5 ° C. for 5 minutes produced a sintered substrate D.

【００１０】（比較例１ 焼結基体Ｅの製造法）焼結基
体Ｃの製造工程において、ニッケル粉末を含むスラリ
に、実施例１と等量の硫酸銅を添加した以外は従来例１
と同条件で焼結基体Ｅを作製した。Comparative Example 1 Manufacturing Method of Sintered Substrate E Conventional Example 1 except that the same amount of copper sulfate as in Example 1 was added to the slurry containing nickel powder in the manufacturing process of the sintered substrate C.
A sintered substrate E was produced under the same conditions as above.

【００１１】焼結基体Ａの断面模式図を図１に示す。ニ
ッケル焼結基体１表面がほぼ均一にCu（耐酸性金属２）
で被覆されていることは、EPMA(electron probe micro
analyzer)による観察で確認した。焼結基体Ｂについて
も同様にニッケル焼結基体１表面がほぼ均一にTi（耐酸
性金属２）で被覆されていた。これは、穿孔板に塗着し
たスラリを乾燥する際に増孔剤が消失し、その表面に付
着した硫酸銅がニッケル粉末表面に付着し、その状態で
焼成工程において還元され、焼結されるものと思われる
が、詳細は明らかでない。また、本実施例、従来例、比
較例の焼結基体は、増孔剤を用いないで製造したものに
比較し、５％程度多孔度が増加した。A schematic sectional view of the sintered substrate A is shown in FIG. The surface of the nickel sintered substrate 1 is almost uniformly Cu (acid resistant metal 2)
It is covered with EPMA (electron probe micro
It was confirmed by observation with an analyzer). Regarding the sintered substrate B, similarly, the surface of the nickel sintered substrate 1 was almost uniformly covered with Ti (acid resistant metal 2). This is because the pore-raising agent disappears when the slurry applied to the perforated plate is dried, the copper sulfate adhering to the surface adheres to the nickel powder surface, and in that state is reduced and sintered in the firing step. Probably, but details are not clear. In addition, the sintered substrates of the present example, the conventional example, and the comparative example had an increase in porosity of about 5% as compared with those produced without using the pore increasing agent.

【００１２】上記焼結基体Ａ〜Ｅをそれぞれ、１００
℃、比重１．７の硝酸ニッケル水溶液に、５分間浸漬
し、乾燥し、８０℃、２０％の苛性ソーダ水溶液中に浸
漬する一連の活物質充填操作を４回繰り返すことによ
り、焼結式ニッケル電極を作製した。Each of the above-mentioned sintered substrates A to E is 100
By immersing in a nickel nitrate aqueous solution having a specific gravity of 1.7 ° C. for 5 minutes, drying, and immersing in an aqueous solution of 20% caustic soda at 80 ° C., a series of operations for filling the active material is repeated four times to obtain a sintered nickel electrode Was produced.

【００１３】ニッケル焼結基体は、含浸操作中に部分的
に腐蝕されるが、腐蝕された部分は、活物質（水酸化ニ
ッケル）化する。そこで、各電極を、８ｗｔ％の酢酸水
溶液に１ｗｔ％の硫酸ヒドラジニウムを溶解した溶液に
５時間電極を浸漬して活物質の除去を行い、各焼結基体
の腐蝕度を、含浸前後の焼結基板の重量減少率として表
１に示す。The nickel sintered substrate is partially corroded during the impregnation operation, and the corroded portion becomes an active material (nickel hydroxide). Therefore, each electrode was immersed in a solution in which 1 wt% hydrazinium sulfate was dissolved in 8 wt% acetic acid aqueous solution for 5 hours to remove the active material, and the degree of corrosion of each sintered substrate was measured before and after impregnation. Table 1 shows the weight reduction rate of the substrate.

【００１４】[0014]

【表１】 [Table 1]

【００１５】表１の結果から、本発明の製造法により得
られた焼結基体Ａ、Ｂの腐蝕度は５％程度に抑さえられ
ているのに対し、従来例、比較例の焼結基体の腐蝕度
は、１４〜２４％と、非常に大きいことが分かる。これ
により、本発明の防蝕効果は明らかである。従来例の焼
結基体Ｃは、増孔剤を用いて高多孔度とした上に、防蝕
処理を施さなかったために２４．３％もの大きい腐蝕度
を示したものと考えられる。また、焼結基体Ｄは、酸化
ニッケル被膜が焼結基体内部まで均一に形成されなかっ
たため、腐蝕が進行したものと考えられる。焼結基体Ｅ
は、焼結基体の製造工程において、ニッケル粉末を含む
スラリに硫酸銅を添加したものである。理由は明らかで
はないが、この方法では均一な被膜が得られにくいた
め、１４．４％もの大きな腐蝕度を示していると考えら
れる。From the results shown in Table 1, the corrosion rates of the sintered substrates A and B obtained by the manufacturing method of the present invention are suppressed to about 5%, while the sintered substrates of the conventional example and the comparative example are suppressed. It can be seen that the corrosion degree of is very large, 14 to 24%. From this, the anticorrosion effect of the present invention is clear. It is considered that the sintered base C of the conventional example exhibited a high degree of corrosion of 24.3% because it was made to have a high porosity by using a pore-forming agent and was not subjected to anticorrosion treatment. Further, in the sintered base D, the nickel oxide coating was not formed evenly inside the sintered base, and therefore it is considered that corrosion progressed. Sintered substrate E
Is a slurry obtained by adding copper sulfate to a slurry containing nickel powder in the manufacturing process of the sintered substrate. Although the reason is not clear, it is considered that this method shows a large degree of corrosion of 14.4% because it is difficult to obtain a uniform film.

【００１６】つぎに、作製した焼結式ニッケル極を同サ
イズに裁断し、公知のカドミニウム負極と、負極／正極
の容量比を１．８とし、電解液には３０ｗｔ％ のＫＯ
Ｈ水溶液を用い、ＳＣＲＶ型のＮｉ−Ｃｄ電池を作製
し、充放電サイクル試験を行った。充放電条件は、充電
１．０Ｃ、１５０％、充電休止１時間、放電１．０Ｃ
（終止電圧１．０Ｖ）である。その結果を図２に示す。
実施例１、２の焼結基体の極板を用いた電池は良好なサ
イクル特性を示した。従来例及び比較例の電池が充放電
サイクル初期に実施例の電池よりも放電容量が大きいの
は、前述したように、従来例及び比較例の電池は、ニッ
ケル基体の腐蝕により活物質量が増加したためと考えら
れる。従来例及び比較例の電池を充放電試験後分解して
みると、明らかにニッケル極活物質の脱落が確認でき
た。腐蝕した焼結基体が活物質を保持しきれなかったた
めである。この結果からも本発明の防蝕効果による寿命
特性向上効果は明らかである。Next, the produced sintered nickel electrode was cut into the same size, the known cadmium negative electrode and the negative electrode / positive electrode capacity ratio were set to 1.8, and the electrolyte solution contained 30 wt% KO.
An SCRV type Ni-Cd battery was produced using the H aqueous solution, and a charge / discharge cycle test was performed. Charge / discharge conditions are: charge 1.0C, 150%, charge pause 1 hour, discharge 1.0C
(Final voltage 1.0 V). The result is shown in FIG.
The batteries using the sintered base plates of Examples 1 and 2 showed good cycle characteristics. The discharge capacity of the batteries of the conventional example and the comparative example is larger than that of the battery of the example at the beginning of the charge / discharge cycle.As described above, the batteries of the conventional example and the comparative example have an increased amount of active material due to corrosion of the nickel substrate. It is thought that it was done. When the batteries of the conventional example and the comparative example were disassembled after the charge / discharge test, it was clearly confirmed that the nickel electrode active material was detached. This is because the corroded sintered substrate cannot hold the active material. From this result, the effect of improving the life characteristics by the anticorrosion effect of the present invention is clear.

【００１７】本実施例では、ＣｕまたはＴｉを用いた
が、その他のニッケルよりイオン化傾向の低い耐酸性の
金属を用いても同様の効果が得られる。また、増孔剤へ
のニッケルよりイオン化傾向の低い、耐酸性の金属ある
いは金属化合物の付着法は、本実施例のみに限定される
ものではなく、静電気による手段等でも構わない。ま
た、本実施例以外の増孔剤を用いても同様の効果が得ら
れる。Although Cu or Ti is used in this embodiment, the same effect can be obtained by using an acid resistant metal having a lower ionization tendency than nickel. Further, the method of attaching the acid-resistant metal or metal compound, which has a lower ionization tendency than nickel, to the pore-forming agent is not limited to this example, and means such as static electricity may be used. Further, the same effect can be obtained by using a pore-forming agent other than that of this example.

【００１８】[0018]

【発明の効果】本発明により、高多孔度で、しかも含浸
工程時の腐蝕を抑制できるニッケル焼結基体の製造法を
提供することができた。According to the present invention, it is possible to provide a method for producing a nickel sintered substrate which has high porosity and can suppress corrosion during the impregnation step.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の製造法により得られた焼結基体の断面
模式図である。FIG. 1 is a schematic sectional view of a sintered substrate obtained by a manufacturing method of the present invention.

【図２】実施例、従来例で作製した焼結基体を用いた電
池の充放電サイクル特性を示した図である。FIG. 2 is a diagram showing charge / discharge cycle characteristics of batteries using the sintered substrates produced in Examples and Conventional Examples.

【符号の説明】[Explanation of symbols]

１はＣｕ、２はニッケル焼結基体。 1 is Cu, 2 is a nickel sintered substrate.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】ニッッケル粉末、増粘剤、分散媒からなる
スラリを穿孔板に塗着して乾燥し、その後還元性、ある
いは非酸化性雰囲気中で焼成する焼結基体の製造法にお
いて、 前記スラリに、耐酸性の金属あるいはその化合物を付着
させた増孔剤を添加することを特徴とするニッケル焼結
基体の製造法。1. A method for producing a sintered substrate, which comprises coating a perforated plate with a slurry comprising nickel powder, a thickener, and a dispersion medium, drying it, and then firing it in a reducing or non-oxidizing atmosphere. A method for producing a nickel-sintered substrate, comprising adding a pore-forming agent having an acid-resistant metal or a compound thereof attached to the slurry.