JP5398050B2 - Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery - Google Patents

Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery Download PDF

Info

Publication number
JP5398050B2
JP5398050B2 JP2008082239A JP2008082239A JP5398050B2 JP 5398050 B2 JP5398050 B2 JP 5398050B2 JP 2008082239 A JP2008082239 A JP 2008082239A JP 2008082239 A JP2008082239 A JP 2008082239A JP 5398050 B2 JP5398050 B2 JP 5398050B2
Authority
JP
Japan
Prior art keywords
cobalt compound
cobalt
phase
hydroxide
positive electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
JP2008082239A
Other languages
Japanese (ja)
Other versions
JP2009234846A (en
Inventor
忠司 掛谷
佳照 川部
誠二郎 落合
正治 綿田
哲男 境
正典 森下
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Institute of Advanced Industrial Science and Technology AIST
GS Yuasa International Ltd
Original Assignee
National Institute of Advanced Industrial Science and Technology AIST
GS Yuasa International Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Institute of Advanced Industrial Science and Technology AIST, GS Yuasa International Ltd filed Critical National Institute of Advanced Industrial Science and Technology AIST
Priority to JP2008082239A priority Critical patent/JP5398050B2/en
Publication of JP2009234846A publication Critical patent/JP2009234846A/en
Application granted granted Critical
Publication of JP5398050B2 publication Critical patent/JP5398050B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Description

本発明は、コバルト化合物、そのコバルト化合物を使用したアルカリ電池、及び、ニッケル基材に、正極活物質として水酸化ニッケルを充填するアルカリ蓄電池用正極の製造方法に関する。   The present invention relates to a cobalt compound, an alkaline battery using the cobalt compound, and a method for producing a positive electrode for an alkaline storage battery in which nickel base is filled with nickel hydroxide as a positive electrode active material.

上記コバルト化合物は、低抵抗のコバルト化合物を必要とする種々の用途への適用が考えられるが、特に、アルカリ蓄電池用正極に利用する場合について説明する。
ニッケル金属水素化物電池、ニッケルカドミウム電池、あるいは、ニッケル亜鉛電池等のアルカリ蓄電池における正極であるニッケル電極として、近年では、従来の焼結式電極に代えて、下記特許文献１にも記載のような、ニッケル基材（ニッケル発泡基材）にペースト状の活物質を充填する非焼結式電極が用いられている。
このペースト式ニッケル電極は、上記活物質である水酸化ニッケルを従来電極よりも多量に充填することができ、容量及びエネルギー密度を向上させることができた。 Although the said cobalt compound can consider the application to the various uses which require a low resistance cobalt compound, the case where it utilizes especially for the positive electrode for alkaline storage batteries is demonstrated.
As a nickel electrode that is a positive electrode in an alkaline storage battery such as a nickel metal hydride battery, a nickel cadmium battery, or a nickel zinc battery, in recent years, instead of the conventional sintered electrode, as described in Patent Document 1 below A non-sintered electrode in which a paste base active material is filled in a nickel base (nickel foam base) is used.
This paste-type nickel electrode was able to fill the active material nickel hydroxide in a larger amount than the conventional electrode, and was able to improve capacity and energy density.

しかしながら、単に水酸化ニッケルをニッケル発泡基材に充填するだけの構成では、ニッケル発泡基材のうちで電池の正極として有効に機能しない領域が少なからず存在し、実用できる水準には達し得なかった。
これは、活物質である水酸化ニッケルは、電池が充電されてオキシ水酸化ニッケルとなっている状態では高い電気導電率（以下、単に「導電率」と称する場合がある）を有する材料であるが、電池の放電に伴って導電率が低下して行き、電極内の導電率が低下した領域が、近接する領域の放電を妨げてしまうことによるものである。 However, in the configuration in which nickel hydroxide is simply filled into the nickel foam base material, there are not a few areas in the nickel foam base material that do not function effectively as the positive electrode of the battery, and the practical level could not be reached. .
This is a material having high electrical conductivity (hereinafter sometimes simply referred to as “conductivity”) in the state where the battery is charged and becomes nickel oxyhydroxide, which is an active material. However, the electrical conductivity decreases with the discharge of the battery, and the region where the electrical conductivity in the electrode is reduced prevents the adjacent region from being discharged.

そこで、電極内の導電性ネットワークが充放電中でも極力維持されるように、導電性の高いコバルト化合物を活物質に添加する手法が考えられている。
このコバルト化合物としては、例えばＣｏ３Ｏ４では導電性ネットワークの維持に効果がなく、Ｃｏ（ＯＨ）２やＣｏＯ等のアルカリ電解液中で可溶なコバルト化合物には効果が認められている。 Therefore, a method of adding a highly conductive cobalt compound to the active material has been considered so that the conductive network in the electrode is maintained as much as possible even during charge and discharge.
As this cobalt compound, for example, Co 3 O 4 has no effect in maintaining a conductive network, and an effect is recognized for a cobalt compound that is soluble in an alkaline electrolyte such as Co (OH) 2 or CoO.

この理由としては、Ｃｏ（ＯＨ）２やＣｏＯを添加すると導電性の高いオキシ水酸化コバルトが生成されることによるものと考えられている。
より詳細に説明すると、Ｃｏ（ＯＨ）２やＣｏＯは、アルカリ水溶液中に溶解して２価のコバルト錯イオンが生成される。この錯イオンが水酸化ニッケルや基材の表面に水酸化コバルトとして析出し、その水酸化コバルトが初期充電過程において酸化され、導電性の高いオキシ水酸化コバルトが生成される。この生成によって活物質粒子間に導電性ネットワークが形成されて、電極内における局所的な非導電箇所の生成が防止され、ニッケルの利用率を向上できると考えられている。 The reason is considered to be that cobalt oxyhydroxide having high conductivity is produced when Co (OH) 2 or CoO is added.
More specifically, Co (OH) 2 and CoO are dissolved in an alkaline aqueous solution to generate a divalent cobalt complex ion. The complex ions are precipitated as nickel hydroxide or cobalt hydroxide on the surface of the base material, and the cobalt hydroxide is oxidized in the initial charging process to generate cobalt oxyhydroxide having high conductivity. It is believed that this generation forms a conductive network between the active material particles, prevents the generation of local nonconductive portions in the electrode, and improves the utilization rate of nickel.

更に、活物質である水酸化ニッケルのペーストに対してコバルト化合物を単に添加するだけでは、コバルト化合物が水酸化ニッケルのペースト中に偏在してしまうため、下記特許文献１に記載のような手法も考えられている。
下記特許文献１では、結晶のｃ軸長が異なるα−Ｃｏ（ＯＨ）２とβ−Ｃｏ（ＯＨ）２との混合体で水酸化ニッケルの表面を被覆した活物質を用いて導電性の向上を図っている。
特開平７−３２０７３３号公報 Further, since the cobalt compound is unevenly distributed in the nickel hydroxide paste simply by adding the cobalt compound to the nickel hydroxide paste, which is an active material, the technique described in Patent Document 1 below is also available. It is considered.
In the following Patent Document 1, the conductivity is improved by using an active material in which the surface of nickel hydroxide is coated with a mixture of α-Co (OH) 2 and β-Co (OH) 2 having different c-axis lengths of crystals. I am trying.
JP-A-7-320733

しかしながら、上記の手法では、水酸化コバルト（Ｃｏ（ＯＨ）２）自体の導電性は低く、水酸化コバルトが電解液内で溶解及び析出を行う過程で導電性を帯びることから、高い導電性を得ることはできない。
コードレスフォンや、デジタルカメラ等の電子機器の普及に伴い、更なる電池の高容量化が望まれる近年、上記の手法では、更なる高容量化のための電極を得るには十分ではなく、更に導電性の高いコバルト化合物が望まれている。
更に、上記のような電解液内での溶解及び析出が起こると、正極だけではなく、正極と負極とを分離するセパレータにまでコバルト化合物の析出が起こり、マイクロショートが発生して自己放電特性を悪化させる畏れもある。
本発明は、かかる実情に鑑みてなされたものであって、その目的は、電解液中での溶解及び析出過程に依らずとも導電率の高いコバルト化合物を提供する点、及び、そのコバルト化合物を使用したアルカリ蓄電池用正極の製造方法を提供する点にある。 However, in the above method, the conductivity of cobalt hydroxide (Co (OH) 2 ) itself is low, and the cobalt hydroxide is conductive in the process of dissolution and precipitation in the electrolyte solution. I can't get it.
With the widespread use of electronic devices such as cordless phones and digital cameras, in recent years, it is desirable to further increase the capacity of batteries, and the above method is not sufficient to obtain electrodes for further increasing the capacity. A cobalt compound having high conductivity is desired.
Furthermore, when dissolution and precipitation in the electrolyte solution as described above occurs, precipitation of the cobalt compound occurs not only in the positive electrode but also in the separator that separates the positive electrode and the negative electrode, and a micro short circuit occurs, resulting in self-discharge characteristics. Some drowning makes it worse.
The present invention has been made in view of such circumstances, and its object is to provide a cobalt compound having high conductivity without depending on the dissolution and precipitation process in the electrolytic solution, and the cobalt compound. It exists in the point which provides the manufacturing method of the used positive electrode for alkaline storage batteries.

本出願の第１の発明は、コバルト化合物が、空間群Ｒ３ｍ構造の結晶構造を有する結晶相を備え、且つ、前記結晶相の少なくとも一部は、結晶構造における層間のサイトにナトリウム原子が存在して（００３）面の面間隔が１３．８Å以上となっているものである。 In a first invention of the present application, the cobalt compound has a crystal phase having a crystal structure of a space group R3m structure, and at least a part of the crystal phase has a sodium atom at a site between layers in the crystal structure. The (003) plane spacing is 13.8 mm or more.

すなわち、本発明の発明者は、コバルト化合物の研究過程において、特有の結晶構造を持つコバルト化合物が特徴的に高い導電率を有することを見出したのである。
その特有の結晶構造とは、コバルト化合物の結晶構造である空間群Ｒ３ｍ構造の結晶構造における（００３）面の面間隔（いわゆる「ｃ軸長」）が１３．８Å以上と特徴的に長いものである。
そして、このようにｃ軸長の長いものほど導電率が高くなることを実験により確認した。
又、結晶構造における層間のサイトにナトリウム原子が存在することで、導電率の高いコバルト化合物となる。
以下に、その理由を説明する。
コバルト化合物の電気伝導性はコバルトの酸化状態が寄与することが明らかになっており、コバルトの酸化数が高いほうがより電気伝導性が高いとされている。
一方、水酸化コバルトを出発物質として酸化処理した場合、Ｃｏの酸化数が２であるＣｏ（ＯＨ） ２ からＣｏの酸化数が３であるＣｏＯＯＨへ変化し、酸化処理の進行によって更に酸化数が上昇していくのであるが、この酸化数の上昇に伴って結晶の格子が短くなり、それによって酸化数の上昇が妨げられることになる。
つまり、結晶格子が短くなると層間隔（上記（００３）面の面間隔）が短くなって、Ｃｏと結合している酸素原子がマイナスの電荷を帯びて互いに反発し合い、それ以上格子が短くなるのを妨げ、結果として酸化数の上昇が妨げられるのである。
これに対して、結晶構造における層間のサイトにナトリウム原子が存在するコバルト化合物では、その層間で柱のような役割を果たし、Ｃｏの酸化が進行しても層間隔の長い状態を保持させるものと考えられる。
このように層間隔が長い状態に保持されることで、酸化数の上昇が妨げられてしまうのを抑制でき、より高次の酸化数を持ち、導電率の高いコバルト化合物となるのである。
以上のメカニズムからわかるように、コバルト化合物中のＲ３ｍ構造の結晶相のうち面間隔が１３．８Å以上となっている部分は、その結晶構造における層間の所定のサイトにナトリウム原子を有していることが好ましい。そのサイトに取り込まれたナトリウム原子の量が多くなるに従って、酸化処理後の層間隔が長くなる傾向があるからである。そのサイトに取り込まれたナトリウムの量は、結晶構造中に存在しうるナトリウムの原子数に対して実際に存在するナトリウム原子数の割合（以下、Ｎａ占有率と称する）で評価することができる。これらのナトリウムの原子数はリートベルト法で解析することにより定量することができる。 That is, the inventors of the present invention have found that a cobalt compound having a specific crystal structure has a characteristically high conductivity in the course of research on cobalt compounds.
The peculiar crystal structure is a characteristically long (003) plane spacing (so-called “c-axis length”) of 13.8 mm or more in the crystal structure of the space group R3m structure which is a crystal structure of a cobalt compound. .
And it was confirmed by experiment that the longer the c-axis length, the higher the conductivity.
In addition, the presence of sodium atoms at the interlayer sites in the crystal structure results in a cobalt compound having high conductivity.
The reason will be described below.
It has been clarified that the oxidation state of cobalt contributes to the electrical conductivity of the cobalt compound, and it is said that the higher the oxidation number of cobalt, the higher the electrical conductivity.
On the other hand, when cobalt hydroxide is used as the starting material, the oxidation number changes from Co (OH) 2 in which the oxidation number of Co is 2 to CoOOH in which the oxidation number of Co is 3, and the oxidation number further increases as the oxidation treatment proceeds. As the oxidation number increases, the crystal lattice becomes shorter as the oxidation number increases, thereby preventing the increase in the oxidation number.
That is, when the crystal lattice is shortened, the layer spacing (the (003) plane spacing) is shortened, the oxygen atoms bonded to Co are negatively charged and repel each other, and the lattice is shortened further. As a result, the increase in oxidation number is prevented.
On the other hand, a cobalt compound in which sodium atoms are present at sites between layers in the crystal structure plays a role like a column between the layers, and maintains a long state between layers even when oxidation of Co proceeds. Conceivable.
By maintaining the long layer spacing in this way, it is possible to prevent the increase in the oxidation number from being hindered, resulting in a cobalt compound having a higher oxidation number and high conductivity.
As can be seen from the above mechanism, the portion of the crystal phase of the R3m structure in the cobalt compound having a plane spacing of 13.8 cm or more has a sodium atom at a predetermined site between the layers in the crystal structure. It is preferable. This is because the layer spacing after the oxidation treatment tends to increase as the amount of sodium atoms taken into the site increases. The amount of sodium taken into the site can be evaluated by the ratio of the number of sodium atoms actually present to the number of sodium atoms that can exist in the crystal structure (hereinafter referred to as Na occupancy). The number of these sodium atoms can be quantified by analyzing the Rietveld method.

又、本出願の第２の発明は、上記第１の発明のコバルト化合物において、（００３）面の面間隔が１３．８Å以上となっている部分の含有量は３１．５ｗｔ％以上である。
すなわち、ｃ軸長の長い部分の割合が多くなるに従って導電率が高くなること及びその割合が３１．５ｗｔ％（重量％）以上となったときに導電率が顕著に向上することを実験により確認した。 In the second invention of the present application, in the cobalt compound of the first invention, the content of the portion where the (003) plane spacing is 13.8 mm or more is 31.5 wt% or more.
That is, it has been confirmed by experiments that the conductivity increases as the proportion of the long c-axis length increases, and that the conductivity significantly increases when the proportion becomes 31.5 wt% (weight%) or more. did.

又、本出願の第３の発明は、上記第１又は第２の発明のコバルト化合物における（００３）面の面間隔が１３．８Å以上となっている部分の結晶構造におけるナトリウム原子の存在可能サイトに対する実際にナトリウム原子が存在するサイトの割合が０．３３１９以上である。 Further, the third invention of the present application is the site where the presence of sodium atoms in the crystal structure of the portion where the (003) plane spacing is 13.8 mm or more in the cobalt compound of the first or second invention. The ratio of sites where sodium atoms are actually present is 0.3319 or more.

又、本出願の第４の発明は、上記第３の発明のコバルト化合物が、ナトリウムイオンを含む水溶液とα相の水酸化コバルトとのペースト状の混合物を酸素雰囲気下で加熱することで前記水酸化コバルトを酸化処理して得られる。
すなわち、本発明の発明者は、コバルト化合物の研究過程において、上記の製作過程を経て得られるコバルト化合物を解析したところ、コバルト化合物が空間群Ｒ３ｍ構造の結晶構造を有する結晶相を備えていることを確認した。そして、その結晶相のｃ軸長に着目して更に解析したところ、その結晶相の中には少なくとも長短２つのｃ軸長の相が混在していること、及び、長い方の相のｃ軸長は１３．８Å以上であり他方のものと較べて大幅に長くなっていることを見出した。尚、以下において、この長短２つのｃ軸長の相について、ｃ軸長の長い方を「Ｌ相」と称し、ｃ軸長の短い方を「Ｓ相」と称する。
このＬ相とＳ相のうち、特にＬ相が高い導電率に寄与していることがわかった。
上記の酸化処理中に、Ｒ３ｍ構造の結晶構造の層間の所定サイトにＮａ＋やＨ２０がインターカレーションし（取込まれ）て結晶構造における層間のサイトにナトリウム原子が存在する状態となり、上記のようにＬ相を形成するのである。 According to a fourth invention of the present application, the cobalt compound of the third invention is prepared by heating a paste-like mixture of an aqueous solution containing sodium ions and an α-phase cobalt hydroxide in an oxygen atmosphere. It is obtained by oxidizing cobalt oxide.
That is, the inventors of the present invention have analyzed the cobalt compound obtained through the above manufacturing process in the cobalt compound research process, and found that the cobalt compound has a crystal phase having a crystal structure of a space group R3m structure. It was confirmed. Further analysis was conducted by paying attention to the c-axis length of the crystal phase. As a result, it was found that at least two c-axis length phases were mixed in the crystal phase, and that the c-axis of the longer phase was mixed. It was found that the length was 13.8 cm or more, which was significantly longer than the other. In the following description, regarding the two phases having the long and short c-axis length, the longer c-axis length is referred to as “L phase”, and the shorter c-axis length is referred to as “S phase”.
Of the L and S phases, it was found that the L phase contributes particularly to high conductivity.
During the above oxidation treatment, Na + or H 2 O is intercalated (incorporated) into a predetermined site between the layers of the crystal structure of the R3m structure, and sodium atoms are present at the sites between the layers in the crystal structure. The L phase is formed as described above.

又、本出願の第５の発明は、上記第１，第２，第３又は第４の発明のコバルト化合物と活物質とを含む電極を備えてアルカリ電池を構成する。
すなわち、上記のように導電率の高いコバルト化合物を電極に構成要素とすることで、電極に良好な導電性ネットワークが形成される。
尚、この「アルカリ電池」は「アルカリ蓄電池」だけでなく「アルカリ一次電池」の概念も含む。 According to a fifth aspect of the present invention, an alkaline battery is configured by including an electrode including the cobalt compound of the first, second, third, or fourth aspect and an active material.
That is, by using a cobalt compound having a high conductivity as a constituent element in the electrode as described above, a good conductive network is formed in the electrode.
The “alkali battery” includes not only the “alkali storage battery” but also the concept of “alkali primary battery”.

又、本出願の第６の発明は、電子伝導性のある基材に、正極活物質として水酸化ニッケルを充填するアルカリ蓄電池用正極の製造方法において、ナトリウムイオンを含む水溶液とα相の水酸化コバルトとを、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）が０．５以上となるように含むペースト状の混合物を６０℃以上で加熱することで前記水酸化コバルトを酸化処理し、その酸化処理によって得られた上記第１〜第４のいずれかのコバルト化合物を前記水酸化ニッケルに混合して前記電子伝導性のある基材に充填する。 According to a sixth aspect of the present application, there is provided a method for producing a positive electrode for an alkaline storage battery in which a base material having electron conductivity is filled with nickel hydroxide as a positive electrode active material. The cobalt hydroxide is oxidized by heating a paste-like mixture containing cobalt so that the atomic ratio of Co and Na (Na / Co) is 0.5 or more, and the oxidation. Any one of the first to fourth cobalt compounds obtained by the treatment is mixed with the nickel hydroxide and filled into the base material having electron conductivity.

すなわち、本発明の発明者は、ＮａＯＨ水溶液と水酸化コバルトとを、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）が０．５以上となるように混合し、その混合物を酸素雰囲気下において６０℃以上で加熱することで前記水酸化コバルトを酸化処理して得られたコバルト化合物が導電率の高いものであることを実験によって確認した。このように高い導電率のものが得られる理由は上述の通りである。
このように高い導電率のコバルト化合物を得られたことから、そのコバルト化合物を活物質である水酸化ニッケルに添加して、コバルト化合物が添加された水酸化ニッケルをニッケル基材に充填することで、導電性ネットワークを良好に構築できるアルカリ蓄電池用正極を製造できた。 That is, the inventor of the present invention mixes an aqueous NaOH solution and cobalt hydroxide so that the atomic ratio of Co to Na (Na / Co) is 0.5 or more, and the mixture is added in an oxygen atmosphere to 60%. It was confirmed by an experiment that the cobalt compound obtained by oxidizing the cobalt hydroxide by heating at a temperature of at least ° C. has high conductivity. The reason why such a high conductivity is obtained is as described above.
Since a cobalt compound having a high conductivity was obtained in this way, the cobalt compound was added to nickel hydroxide as an active material, and the nickel base material was filled with the nickel hydroxide to which the cobalt compound was added. Thus, a positive electrode for an alkaline storage battery capable of satisfactorily constructing a conductive network could be manufactured.

尚、ここで、ＮａＯＨ水溶液と水酸化コバルトとの混合の仕方として、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）が０．５以上となるようにしているのは、酸化処理を行う際のＮａ量が少ないと、層間にＮａが取込まれる割合が少なくなり、層間隔の長いＬ相が生成されにくくなるためである。
更に、ナトリウムイオンを含む水溶液と水酸化コバルトとの混合物を加熱する温度を６０℃以上としているのは、加熱温度が低いとＣｏの酸化が十分に進行せず、層間にＮａが取り込まれる割合が少なくなって層間隔の長いＬ相が生成されにくくなり、導電率の低いものが生成されてしまうからである。 Here, as a method of mixing the NaOH aqueous solution and cobalt hydroxide, the atomic ratio of Co to Na (Na / Co) is set to 0.5 or more when the oxidation treatment is performed. This is because when the amount of Na is small, the proportion of Na taken in between the layers decreases, and it becomes difficult to generate an L phase with a long interlayer spacing.
Furthermore, the temperature at which the mixture of the aqueous solution containing sodium ions and cobalt hydroxide is heated to 60 ° C. or higher is that, when the heating temperature is low, the oxidation of Co does not proceed sufficiently and the proportion of Na taken in between the layers is high. This is because the L phase with a long inter-layer spacing is less likely to be generated, and a low conductivity is generated.

又、本出願の第７の発明は、上記第６の発明において、前記ナトリウムイオンを含む水溶液と水酸化コバルトとを含む混合物を加熱する温度を１００℃以上とする。
このように加熱する温度を設定することで、より一層導電率が向上することを実験により確認した。 Moreover, 7th invention of this application makes the temperature which heats the mixture containing the aqueous solution containing the said sodium ion and cobalt hydroxide in the said 6th invention to 100 degreeC or more.
It was confirmed by experiments that the conductivity was further improved by setting the heating temperature in this way.

上記第１の発明によれば、（００３）面の面間隔が１３．８Å以上となる相を含むコバルト化合物によって、導電率の高いコバルト化合物を提供することができ、後述するアルカリ蓄電池用正極等の、導電率の高いコバルト化合物が望まれる種々の用途に用いることができる。   According to the first aspect of the invention, a cobalt compound having a high conductivity can be provided by a cobalt compound containing a phase having a (003) plane spacing of 13.8 mm or more. It can be used in various applications where a cobalt compound with high conductivity is desired.

又、上記第２の発明によれば、（００３）面の面間隔が１３．８Å以上となっている部分の含有量を３１．５ｗｔ％以上とすることで、コバルト化合物の導電率を顕著に向上させることができた。
又、上記第３の発明によれば、結晶構造における層間のサイトにナトリウム原子が存在することで、導電率の高いコバルト化合物が得られる。 According to the second aspect of the invention, the conductivity of the cobalt compound is remarkably increased by setting the content of the portion where the (003) plane spacing is 13.8 mm or more to 31.5 wt% or more. I was able to improve.
Moreover, according to the said 3rd invention, a cobalt compound with high electrical conductivity is obtained because a sodium atom exists in the site | part between the layers in crystal structure.

又、上記第４の発明によれば、ナトリウムイオンを含む水溶液と水酸化コバルトとの混合物を加熱することで前記水酸化コバルトを酸化処理して得られるコバルト化合物が、空間群Ｒ３ｍ構造の結晶構造を有する結晶相を備え、且つ、前記結晶相の少なくとも一部は、（００３）面の面間隔が１３．８Å以上のコバルト化合物となっており、導電率の高いコバルト化合物を提供できる。
又、上記第５の発明によれば、電極に良好な導電性ネットワークが形成されるので、アルカリ電池の更なる高容量化を図れる。 According to the fourth aspect of the invention, the cobalt compound obtained by oxidizing the cobalt hydroxide by heating a mixture of an aqueous solution containing sodium ions and cobalt hydroxide has a crystal structure of a space group R3m structure. And at least part of the crystal phase is a cobalt compound having a (003) plane spacing of 13.8 mm or more, and can provide a cobalt compound having high conductivity.
Further, according to the fifth aspect, since a good conductive network is formed on the electrode, the capacity of the alkaline battery can be further increased.

又、上記第６の発明によれば、高い導電率のコバルト化合物を利用して導電性ネットワークを良好に構築できるアルカリ蓄電池用正極を製造できるので、電池のより一層の高容量化を実現することができる。
更には、コバルト化合物が高い導電率を有することで、水酸化ニッケルに添加するコバルト化合物の量を少なくすることもでき、製造コストの低減も図れる。
又、上記第７の発明によれば、より一層導電率が向上したコバルト化合物を使用して、導電性ネットワークを更に良好に構築したアルカリ蓄電池用正極を製造できる。 According to the sixth aspect of the invention, a positive electrode for an alkaline storage battery capable of satisfactorily constructing a conductive network using a cobalt compound having a high conductivity can be manufactured, so that the capacity of the battery can be further increased. Can do.
Furthermore, since the cobalt compound has high conductivity, the amount of the cobalt compound added to nickel hydroxide can be reduced, and the manufacturing cost can be reduced.
Moreover, according to the said 7th invention, the positive electrode for alkaline storage batteries which constructed | assembled the electroconductive network further more satisfactorily can be manufactured using the cobalt compound from which the electrical conductivity improved further.

以下、本発明の実施の形態を図面等に基づいて説明する。
〔コバルト化合物の製作〕
コバルト化合物の製造には、α相の水酸化コバルトの粉末を原料として使用する。水酸化コバルトには、よりｃ軸長の短いβ相の水酸化コバルトも存在するが、ｃ軸長の短いβ相の水酸化コバルトでは、Ｎａ＋やＨ２０の層間へのインターカレーションがα相のものに較べて起こりにくく、より導電率の高いコバルト化合物を得るにはα相の水酸化コバルトを用いるのが好ましい。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Production of cobalt compounds]
In the production of the cobalt compound, α-phase cobalt hydroxide powder is used as a raw material. Cobalt hydroxide also has β-phase cobalt hydroxide with a shorter c-axis length, but β-phase cobalt hydroxide with a shorter c-axis length causes intercalation between Na + and H 2 O layers. It is preferable to use α-phase cobalt hydroxide to obtain a cobalt compound which is less likely to occur than the α-phase one and has higher conductivity.

原料のα相の水酸化コバルトの粉末を、水酸化ナトリウム水溶液と混合し、酸素雰囲気下において設定加熱温度で加熱する。この加熱によって水酸化コバルトの酸化が進行する。尚、この加熱処理においては、通常用いられる酸化剤（次亜塩素酸ナトリウム、過マンガン酸カリウムなど）を用いても良い。又、この加熱処理においては、水酸化ナトリウム水溶液に代えて、ナトリウムイオンを含む水溶液を用いることができる。
「酸素雰囲気下」としているように、水酸化コバルトと水酸化ナトリウムとの混合物は、液状ではなく水分が少な目のペースト状となっていることが好ましい。
上記の加熱処理の加熱時間（酸化処理時間）は、より確実に酸化を進行させるために１時間としているが、３０分以上であれば、上記Ｌ相を生成するのに十分である。
加熱処理が完了すると、その後、水洗し、十分乾燥させる。
以上の処理で目的のコバルト化合物の粉末が生成される。 Raw material α-phase cobalt hydroxide powder is mixed with an aqueous sodium hydroxide solution and heated at a set heating temperature in an oxygen atmosphere. By this heating, oxidation of cobalt hydroxide proceeds. In this heat treatment, a commonly used oxidizing agent (sodium hypochlorite, potassium permanganate, etc.) may be used. In this heat treatment, an aqueous solution containing sodium ions can be used instead of the aqueous sodium hydroxide solution.
As described in “in an oxygen atmosphere”, the mixture of cobalt hydroxide and sodium hydroxide is preferably not in a liquid form but in a paste form with a small amount of water.
The heating time (oxidation time) of the heat treatment is set to one hour in order to make the oxidation proceed more reliably, but if it is 30 minutes or longer, it is sufficient to generate the L phase.
When the heat treatment is completed, it is then washed with water and sufficiently dried.
With the above treatment, a powder of the target cobalt compound is generated.

上記のコバルト化合物の製作工程における作製条件について更に詳述すると、コバルト化合物の作製パラメータとして、加熱処理（酸化処理）の際の加熱温度、及び、水酸化コバルトと水酸化ナトリウム水溶液との混合の割合があり、以下の第１及び第２の２つの作製条件群でこれらの作製パラメータを変化させてコバルト化合物を作製した。   The production conditions in the production process of the cobalt compound will be described in further detail. The production parameters of the cobalt compound include the heating temperature during the heat treatment (oxidation treatment) and the mixing ratio of the cobalt hydroxide and the sodium hydroxide aqueous solution. Cobalt compounds were produced by changing these production parameters under the following first and second production condition groups.

第１の作製条件群では、水酸化コバルトと水酸化ナトリウム水溶液との混合の割合としては、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）で「１」となるように両者を調製して変化させず、前記加熱処理の際の加熱温度については、６０℃，８０℃，１００℃，１１０℃，１２０℃，１３０℃，１４０℃，１５０℃，及び，１６０℃の夫々の加熱温度でコバルト化合物を作製した。
ここで、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）で「１」とする調製は、具体的には、α相を有する水酸化コバルトを１９ｇ秤量し、４８％の水酸化ナトリウム水溶液２０ｇと混合すれば良い。 In the first production condition group, the mixing ratio of cobalt hydroxide and sodium hydroxide aqueous solution was changed by adjusting both of them so that the atomic ratio of Co and Na (Na / Co) was “1”. As for the heating temperature during the heat treatment, cobalt compounds are used at respective heating temperatures of 60 ° C, 80 ° C, 100 ° C, 110 ° C, 120 ° C, 130 ° C, 140 ° C, 150 ° C, and 160 ° C. Was made.
Here, the preparation for setting the atomic ratio of Co to Na (Na / Co) to “1” is specifically, 19 g of cobalt hydroxide having an α phase is weighed, and 20 g of 48% sodium hydroxide aqueous solution is added. Mix it.

第２の作製条件群は、前記加熱処理の加熱温度については変化させずに１２０℃に固定し、水酸化コバルトと水酸化ナトリウム水溶液との混合の割合としては、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）で、０．５，１，１．５，２の各値となるように水酸化コバルトと水酸化ナトリウム水溶液とを秤量して混合した。   The second production condition group was fixed at 120 ° C. without changing the heating temperature of the heat treatment, and the mixing ratio of cobalt hydroxide and sodium hydroxide aqueous solution was the atomic ratio of Co and Na ( Na / Co), cobalt hydroxide and sodium hydroxide aqueous solution were weighed and mixed so as to have values of 0.5, 1, 1.5, and 2, respectively.

〔作製したコバルト化合物の特性測定〕
上記の第１の作製条件群と、第２の作製条件群とで作製したコバルト化合物の粉末の特性を、Ｘ線回折装置（ＢｒｕｋｅｒＡＸＳ社製、品番Ｍ０６ＸＣＥ、測定条件４０ｋＶ、１００ｍＡ（Ｃｕ管球））と、粉体抵抗測定とによって測定した。
Ｘ線回折装置による測定結果をリートベルト法（解析ソフト：ＲＩＥＴＡＮ２０００）によって解析することによって、粉末中のコバルト化合物の結晶構造を特定できると共に、その結晶構造における各結晶軸での軸長の特定や、特定した結晶構造を有する相の存在割合や、どのような不純物が含まれるかの特定も行える他、種々の組成物の存在割合、結晶相内の所定のサイトにどの程度Ｎａが取込まれているか等も検出できる。
粉体抵抗測定では、半径０．４ｍｍの円形の型に加熱処理（酸化処理）したコバルト化合物の粉末を５０ｍｇ入れて１０ＭＰａで加圧し、測定を行った。この測定結果から、コバルト化合物の粉末の比抵抗値（導電率の逆数）が得られる。 [Characteristic measurement of prepared cobalt compound]
The characteristics of the cobalt compound powder produced in the first production condition group and the second production condition group were measured using an X-ray diffractometer (manufactured by BrukerAX, product number M06XCE, measurement conditions 40 kV, 100 mA (Cu tube). ) And powder resistance measurement.
By analyzing the measurement results by the X-ray diffractometer using the Rietveld method (analysis software: RIETRAN 2000), the crystal structure of the cobalt compound in the powder can be specified, and the axial length of each crystal axis in the crystal structure can be specified. In addition to specifying the abundance of the phase having the specified crystal structure and what impurities are included, the abundance of various compositions, and how much Na is taken into a given site in the crystal phase It can also be detected.
In the powder resistance measurement, 50 mg of cobalt compound powder heat-treated (oxidized) was put in a circular mold having a radius of 0.4 mm, and the measurement was performed by pressurizing at 10 MPa. From this measurement result, the specific resistance value (reciprocal of conductivity) of the powder of the cobalt compound is obtained.

〔コバルト化合物の特性測定結果〕
Ｘ線回折装置による測定結果から、上記のようにして作製したコバルト化合物の粉末は、共通して、空間群Ｒ３ｍ構造の結晶構造を有する結晶相を有していることを確認できた。
この結晶構造は、図１０に示すような構造を有している。
図１０では、結晶中にカリウム（Ｋ）が取込まれた場合の構造モデルを示しているが、Ｎａが取込まれた場合も同様の構造であり、ＫをＮａに置き換えれば良い。このモデルの中でＫが配置されているサイトが、上述の「所定のサイト」であり、後述の「ナトリウムが存在しうるサイト」である。層間にナトリウムが取り込まれたとき、ナトリウムはこのサイトに存在することとなる。
従って、上記のようにして作製したコバルト化合物は、Ｃｏ，Ｏ，Ｎａ，Ｈの各元素で構成され、厳密には酸化処理の進行度合いによって組成式が変化して行く。もちろん、製作したコバルト化合物中の場所によっても組成比が異なる。
図１０において「ｃ軸長」として示す長さが、空間群Ｒ３ｍ構造の結晶構造における（００３）面の面間隔に相当する。 [Characteristic measurement results of cobalt compounds]
From the measurement results by the X-ray diffractometer, it was confirmed that the cobalt compound powder produced as described above had a crystal phase having a crystal structure of the space group R3m structure in common.
This crystal structure has a structure as shown in FIG.
FIG. 10 shows a structural model in the case where potassium (K) is incorporated into the crystal, but the structure is similar when Na is incorporated, and K may be replaced with Na. The site where K is arranged in this model is the above-mentioned “predetermined site”, and is a “site where sodium can be present” described later. When sodium is taken up between the layers, it will be present at this site.
Therefore, the cobalt compound produced as described above is composed of Co, O, Na, and H elements, and strictly speaking, the composition formula changes depending on the degree of progress of the oxidation treatment. Of course, the composition ratio varies depending on the location in the manufactured cobalt compound.
The length shown as “c-axis length” in FIG. 10 corresponds to the (003) plane spacing in the crystal structure of the space group R3m structure.

Ｘ線回折装置による測定結果からは、更に、上記の条件で作製したコバルト化合物の粉末が非常に特徴的な結晶構造を備えた粒子を含んでいることがわかった。
すなわち、コバルト化合物の粉末は、Ｒ３ｍ構造の結晶構造を有する結晶相を備えた粒子を含み、その結晶相の中に、ｃ軸長が異なる構造の二つの相（上記「Ｌ相」と上記「Ｓ相」）が存在し、Ｌ相のｃ軸長は１３．８Å以上であることを見出した。又、このＬ相には、層間のサイトにナトリウムが取り込まれていることを見出した。 From the measurement result by the X-ray diffractometer, it was further found that the cobalt compound powder produced under the above conditions contained particles having a very characteristic crystal structure.
That is, the cobalt compound powder includes particles having a crystal phase having a crystal structure of R3m structure, and includes two phases (the “L phase” and the “ S phase ") existed, and the c-axis length of the L phase was found to be 13.8 mm or more. In addition, the present inventors have found that sodium is taken into the interlayer site in this L phase.

上記第１の作製条件群で作製したコバルト化合物の特性測定結果を整理したものを図７に示す。
図７では、各加熱温度に対して、コバルト化合物の粉末中に含まれるＬ相とＳ相との重量％（同図中で「ｗｔ％」と表記）による存在割合，比抵抗値，ａ軸長，ｃ軸長，及び，Ｎａ占有率を示している。
ここで、Ｎａ占有率とは、結晶構造中のＮａが存在しうるサイトに実際にどの程度Ｎａが存在するかを示す数値であり、「１．０」で全てのＮａが存在しうるサイトにＮａが存在するということを意味する。 FIG. 7 shows a summary of the characteristic measurement results of the cobalt compound produced under the first production condition group.
In FIG. 7, for each heating temperature, the abundance ratio, specific resistance value, a-axis of the L phase and the S phase contained in the cobalt compound powder by weight% (indicated as “wt%” in the figure) The length, c-axis length, and Na occupancy are shown.
Here, the Na occupancy is a numerical value indicating how much Na actually exists at a site where Na in the crystal structure can exist, and “1.0” indicates a site where all Na can exist. It means that Na is present.

次ぎに、図７の測定結果に基づいて、コバルト化合物の比抵抗値と加熱温度との関係をプロットしたものを図１に示す。
図１では、縦軸に比抵抗値を、横軸に上記加熱処理での加熱温度をとっている。
図１の測定結果は、加熱処理の温度が６０℃の時点で既に比抵抗値が下がってきており、１００℃まで比抵抗値が低下して、１００℃以上では非常に低い比抵抗値を維持している。
従って、上記加熱処理での加熱温度は、６０℃以上で良いが、１００℃以上とすることがより好ましい。加熱温度を６０℃以上としておけば、Ｎａ占有率が０．３２１８以上となって、Ｌ相が効率的に生成することになる。Ｎａ占有率は、Ｌ相の層間を長くする観点から０．３３１９以上であることが好ましく、さらに比抵抗値を低減する観点から０．３５１１以上、さらには０．３７１９以上であることが好ましい。 Next, FIG. 1 shows a plot of the relationship between the specific resistance value of the cobalt compound and the heating temperature based on the measurement results of FIG.
In FIG. 1, the vertical axis represents the specific resistance value, and the horizontal axis represents the heating temperature in the heat treatment.
The measurement results in FIG. 1 show that the specific resistance value has already decreased when the temperature of the heat treatment is 60 ° C., the specific resistance value has decreased to 100 ° C., and a very low specific resistance value is maintained above 100 ° C. doing.
Therefore, the heating temperature in the above heat treatment may be 60 ° C. or higher, but more preferably 100 ° C. or higher. If heating temperature shall be 60 degreeC or more, Na occupation rate will be 0.3218 or more and L phase will produce | generate efficiently. The Na occupancy is preferably 0.3319 or more from the viewpoint of lengthening the L-phase interlayer, and more preferably 0.3511 or more, and further preferably 0.3719 or more from the viewpoint of reducing the specific resistance value.

次ぎに、コバルト化合物のＬ相及びＳ相のｃ軸長と加熱温度との関係をプロットしたものを図２に示す。
上述のように、ｃ軸長がＬ相とＳ相との２つのグループに分離していることが良くわかり、Ｌ相及びＳ相の何れについても、加熱温度の上昇に伴ってｃ軸長が長くなっている。
加熱温度が６０℃でも、Ｌ相のｃ軸長が１３．８Åと長い値になっている。
ここで、上記のように加熱処理の加熱温度が１００℃以上であることが好ましいこととの関係で、ｃ軸長は１４．２Å以上であることがより好ましいことになる。 Next, FIG. 2 shows a plot of the relationship between the c-axis length of the L phase and S phase of the cobalt compound and the heating temperature.
As described above, it can be clearly seen that the c-axis length is separated into two groups of the L-phase and the S-phase, and the c-axis length increases as the heating temperature increases for both the L-phase and the S-phase. It is getting longer.
Even when the heating temperature is 60 ° C., the c-axis length of the L phase is as long as 13.8 mm.
Here, as described above, the c-axis length is more preferably 14.2 mm or more in relation to the heating temperature of the heat treatment being preferably 100 ° C. or more.

図２からわかるとおり、加熱温度が１１０℃を超えると、Ｓ相においてもｃ軸長が急激に長くなり、とくに１３０℃を超えると約１３．８Åに達し、１４０℃を超えると１３．８Åを超えることになる。そのため、これらの温度の加熱処理を経たコバルト化合物は、Ｌ相及びＳ相の両方に導電性を向上させる効果が優れていることになり、比抵抗値が極めて低い水準となる。   As can be seen from FIG. 2, when the heating temperature exceeds 110 ° C., the c-axis length in the S phase also increases abruptly. It will exceed. Therefore, the cobalt compound that has undergone the heat treatment at these temperatures has an excellent effect of improving conductivity in both the L phase and the S phase, and the specific resistance value is at a very low level.

図７の測定結果における「相の割合」を、各要素の割合を棒グラフ状に各加熱温度毎に示したものが図３である。
加熱温度が１４０℃以上では、比抵抗値だけを見れば十分に小さい値となっているが、導電率の低いＣｏ３Ｏ４やＣｏＯが生成されており、このような導電率の低いいわば不純物を排除する観点からは、加熱温度は１３０℃以下とすることが好ましい。
図３からＬ相の存在割合だけを抜き出して、それらと比抵抗値との関係を示したものが図４である。
図４から、Ｌ相の存在割合の増大に伴って比抵抗値が減少しており、Ｌ相がコバルト化合物の導電率の高さに寄与していることが良くわかる。更にこの図から、Ｌ相の割合が３１．５ｗｔ％以上のとき顕著に低い比抵抗値となっており、とくに４０．１％以上のとき比抵抗値が極めて低い水準となっていることがわかる。これらのことから考えると、Ｒ３ｍ構造の結晶相の全部をｃ軸長が１３．８Å以上の相としても本発明の効果が得られることは明らかであるし、ｃ軸長が１３．８Å以上の相が複数相混在していても、本発明の効果が得られることは明らかであるし、ｃ軸長が１３．８Å以上の相が少なくとも７．９ｗｔ％以上、好ましくは３１．５ｗｔ％以上含まれさえすれば、１３．８Å未満の相が複数相存在していても本発明の効果が得られることは明らかである。 FIG. 3 shows the “phase ratio” in the measurement results of FIG. 7 and the ratio of each element in a bar graph for each heating temperature.
When the heating temperature is 140 ° C. or higher, the value is sufficiently small if only the specific resistance value is observed, but Co 3 O 4 and CoO with low conductivity are generated, and so-called impurities with low conductivity are generated. From the viewpoint of eliminating the above, the heating temperature is preferably 130 ° C. or lower.
FIG. 4 shows only the L phase existence ratio extracted from FIG. 3 and shows the relationship between them and the specific resistance value.
FIG. 4 clearly shows that the specific resistance value decreases with an increase in the proportion of the L phase, and that the L phase contributes to the high conductivity of the cobalt compound. Furthermore, it can be seen from this figure that the resistivity value is remarkably low when the ratio of the L phase is 31.5 wt% or more, and the resistivity value is particularly low when it is 40.1% or more. . Considering these facts, it is clear that the effects of the present invention can be obtained even if the entire crystal phase of the R3m structure is a phase having a c-axis length of 13.8 mm or more, and the c-axis length is 13.8 mm or more. It is clear that the effects of the present invention can be obtained even when a plurality of phases are mixed, and at least 7.9 wt%, preferably 31.5 wt% or more of phases having a c-axis length of 13.8 mm or more are included. As long as this is done, it is clear that the effects of the present invention can be obtained even if there are a plurality of phases of less than 13.8 mm.

更に、図７の測定結果から、結晶構造におけるａ軸長と加熱温度との関係をプロットしたものを図５に示す。
図５では、ｃ軸長の場合と異なり、加熱温度の上昇に伴ってａ軸長が短くなっていくことが把握できる。 Furthermore, FIG. 5 shows a plot of the relationship between the a-axis length and the heating temperature in the crystal structure from the measurement results of FIG.
In FIG. 5, unlike the case of the c-axis length, it can be understood that the a-axis length becomes shorter as the heating temperature increases.

次ぎに、上記第２の作製条件群で作製したコバルト化合物の特性測定結果を整理したものを図８に示す。
図８では、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）の値夫々に対して、Ｌ相とＳ相との重量％（同図中で「ｗｔ％」と表記）による存在割合，比抵抗値，ａ軸長，ｃ軸長，及び，Ｎａ占有率を示している。
図８の測定結果では、ＣｏとＮａとの原子比の変化に対して、比抵抗値の測定結果等はそれほど特徴的な変化を示していない。
従って、Ｎａ量が少ないと、層間にＮａが取込まれる割合が少なくなり、層間隔の長いＬ層が生成されにくくなると考えられるが、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）を０．５以上としておけば、Ｎａ占有率が０．２８７８以上となって、Ｌ相が効率的に生成することになる。 Next, FIG. 8 shows a summary of the characteristic measurement results of the cobalt compound produced under the second production condition group.
In FIG. 8, for each value of atomic ratio (Na / Co) of Co and Na, the abundance ratio and specific resistance by weight% of L phase and S phase (denoted as “wt%” in the figure). The value, a-axis length, c-axis length, and Na occupancy are shown.
In the measurement result of FIG. 8, the measurement result of the specific resistance value or the like does not show a very characteristic change with respect to the change in the atomic ratio between Co and Na.
Therefore, if the amount of Na is small, the proportion of Na taken in between layers decreases, and it is considered that an L layer having a long layer interval is difficult to be generated. However, the atomic ratio of Co to Na (Na / Co) is set to 0. If it is set to 5 or more, the Na occupancy becomes 0.2878 or more, and the L phase is efficiently generated.

〔比較実験〕
上述のように本発明を適用して作製したコバルト化合物と比較するために、上述のコバルト化合物の作製条件のうちの水酸化ナトリウム水溶液に代えて水酸化カリウム水溶液を使用してコバルト化合物を作製する比較実験を行った。
コバルト化合物の作製手順は上述の水酸化ナトリウム水溶液を使用する場合と同様であり、作製条件の変化パラメータとして、上記第２の作製条件群に準じて、加熱処理の加熱温度については変化させずに１２０℃に固定し、水酸化コバルトと水酸化カリウム水溶液との混合の割合としては、ＣｏとＫとの原子比（Ｋ／Ｃｏ）で、０．５，１の各値となるように水酸化コバルトと水酸化カリウム水溶液とを秤量して混合した。 [Comparison experiment]
In order to compare with the cobalt compound produced by applying the present invention as described above, the cobalt compound is produced using a potassium hydroxide aqueous solution instead of the sodium hydroxide aqueous solution among the production conditions of the cobalt compound described above. A comparative experiment was conducted.
The procedure for preparing the cobalt compound is the same as that in the case of using the above-mentioned sodium hydroxide aqueous solution, and the heating temperature of the heat treatment is not changed as the change parameter of the manufacturing condition in accordance with the second manufacturing condition group. The mixture ratio of cobalt hydroxide and potassium hydroxide aqueous solution is fixed at 120 ° C., and the hydroxyl ratio is set so that the atomic ratio of Co and K (K / Co) is 0.5 and 1, respectively. Cobalt and an aqueous potassium hydroxide solution were weighed and mixed.

このように作製したコバルト化合物について、上記と同様にＸ線回折装置による測定及び粉体抵抗の測定を行った結果を図９に示す。
図９では、ＣｏとＫとの原子比（Ｋ／Ｃｏ）の値夫々に対して、比抵抗値，ａ軸長，ｃ軸長，及び，Ｋ占有率（ナトリウムをカリウムに変更した以外はＮａ占有率と同じ内容で定義される値）を示している。
図９に示すように、水酸化カリウム水溶液を使用した場合では、Ｒ３ｍ構造の結晶構造を有する結晶相を備えていることは確認できたが、その結晶相には、水酸化ナトリウム水溶液を使用した場合のような「Ｌ相」，「Ｓ相」の２つｃ軸長の混在は発生せず、単一のｃ軸長を有するもののみであり、その長さは約７．４Åと短いものであった。
図９の測定結果の比抵抗値を、水酸化ナトリウムを使用してコバルト化合物を作製した場合において作製条件が対応するものと比較したものが図６である。
図９から、本発明を適用して作製したコバルト化合物の比抵抗値が圧倒的に低いものであることがわかる。 FIG. 9 shows the results obtained by measuring the cobalt compound thus prepared by the X-ray diffractometer and the powder resistance in the same manner as described above.
In FIG. 9, for each value of atomic ratio (K / Co) between Co and K, the specific resistance value, a-axis length, c-axis length, and K occupancy (Na except that sodium is changed to potassium) The value defined with the same content as the occupation rate).
As shown in FIG. 9, in the case of using an aqueous potassium hydroxide solution, it was confirmed that a crystal phase having an R3m crystal structure was provided, but an aqueous sodium hydroxide solution was used for the crystal phase. There is no mixing of the two c-axis lengths of “L phase” and “S phase” as in the case, only one having a single c axis length, and the length is as short as about 7.4 mm. Met.
FIG. 6 shows a comparison of the specific resistance value of the measurement result of FIG. 9 with that corresponding to the production conditions when a cobalt compound is produced using sodium hydroxide.
FIG. 9 shows that the specific resistance value of the cobalt compound produced by applying the present invention is extremely low.

〔アルカリ蓄電池用正極の製造〕
上述のように上記第１の作製条件群あるいは上記第２の作製条件群等の本発明を適用した作製条件でコバルト化合物を作製して、それを活物質である水酸化ニッケルの粉末に添加し、その混合粉末にカルボキシメチルセルロース（ＣＭＣ）水溶液等を添加してペースト状とする。コバルト化合物の混合量は、コバルト化合物と水酸化ニッケルとの合計に対して０．１ｗｔ％以上５ｗｔ％以下とすることができる。
このペーストを多孔質のニッケル基材（ニッケル発泡基材）などの電子伝導性のある基材に充填して、その後乾燥処理し、所定の厚みにプレスしてアルカリ蓄電池用正極とする。 [Manufacture of positive electrode for alkaline storage battery]
As described above, a cobalt compound is produced under the production conditions to which the present invention is applied, such as the first production condition group or the second production condition group, and added to the nickel hydroxide powder as an active material. Then, a carboxymethyl cellulose (CMC) aqueous solution or the like is added to the mixed powder to obtain a paste. The mixing amount of the cobalt compound can be 0.1 wt% or more and 5 wt% or less with respect to the total of the cobalt compound and nickel hydroxide.
This paste is filled in a base material having electron conductivity such as a porous nickel base material (nickel foam base material), then dried, and pressed to a predetermined thickness to obtain a positive electrode for an alkaline storage battery.

〔アルカリ蓄電池の製造〕
アルカリ蓄電池としてニッケル水素電池を製造する場合の工程を概略的に説明する。尚、各部の溶接等の詳細な説明については記載を省略する。
鉄にニッケルメッキを施したパンチング鋼板からなる負極基板に水素吸蔵合金粉末を主成分とするペーストを塗布し、乾燥した後に所定の厚みにプレスして負極を作製する。
この負極とポリプロピレンの不織布製セパレータと上述の正極とを積層し、その積層体をロール状に捲回する。
これに正極集電板及び負極集電板を取り付けた後、有底筒状の缶体に挿入し、電解液を注液する。
この後、周囲にリング状のガスケットが取り付けられると共にキャップ状の端子等を備えた円板状の蓋体を、正極集電板と電気的に接触する状態で取り付け、前記缶体の開放端をかしめることで固定する。 [Manufacture of alkaline storage batteries]
The process in the case of manufacturing a nickel metal hydride battery as an alkaline storage battery will be schematically described. In addition, description is abbreviate | omitted about detailed description, such as welding of each part.
A paste mainly composed of a hydrogen storage alloy powder is applied to a negative electrode substrate made of a punched steel plate in which nickel is plated on iron, dried, and then pressed to a predetermined thickness to produce a negative electrode.
The negative electrode, a polypropylene nonwoven fabric separator, and the positive electrode described above are laminated, and the laminate is wound into a roll.
After attaching a positive electrode current collecting plate and a negative electrode current collecting plate to this, it inserts in a bottomed cylindrical can body and injects electrolyte solution.
After that, a ring-shaped gasket is attached to the periphery, and a disc-shaped lid provided with a cap-shaped terminal or the like is attached in a state of being in electrical contact with the positive electrode current collector plate, and the open end of the can body is attached. Fix by caulking.

〔別実施形態〕
上記実施の形態では、本発明を適用するアルカリ電池として、ニッケル水素電池を例示したが、ニッケルカドミウム電池等の各種のアルカリ蓄電池、アルカリ一次電池の電極の製造に適用できる。 [Another embodiment]
In the said embodiment, although the nickel hydride battery was illustrated as an alkaline battery to which this invention is applied, it is applicable to manufacture of the electrodes of various alkaline storage batteries, such as a nickel cadmium battery, and an alkaline primary battery.

本発明の実施の形態にかかるコバルト化合物の比抵抗値と加熱温度との関係を示す図The figure which shows the relationship between the specific resistance value of the cobalt compound concerning embodiment of this invention, and heating temperature 本発明の実施の形態にかかるコバルト化合物のｃ軸長と加熱温度との関係を示す図The figure which shows the relationship between c-axis length of the cobalt compound concerning embodiment of this invention, and heating temperature 本発明の実施の形態にかかるコバルト化合物のＬ相とＳ相との割合と加熱温度との関係を示す図The figure which shows the relationship between the ratio of the L phase of the cobalt compound concerning embodiment of this invention, and the S phase, and heating temperature 本発明の実施の形態にかかるコバルト化合物の比抵抗値とＬ相の割合との関係を示す図The figure which shows the relationship between the specific resistance value of the cobalt compound concerning embodiment of this invention, and the ratio of the L phase. 本発明の実施の形態にかかるコバルト化合物のａ軸長と加熱温度との関係を示す図The figure which shows the relationship between a-axis length of the cobalt compound concerning embodiment of this invention, and heating temperature 本発明の実施の形態にかかるコバルト化合物と比較例との比抵抗値の比較を示す図The figure which shows the comparison of the specific resistance value of the cobalt compound concerning embodiment of this invention, and a comparative example 本発明の実施の形態にかかるコバルト化合物の特性測定結果を示す図表The chart which shows the characteristic measurement result of the cobalt compound concerning an embodiment of the invention 本発明の実施の形態にかかるコバルト化合物の特性測定結果を示す図表The chart which shows the characteristic measurement result of the cobalt compound concerning an embodiment of the invention 本発明の実施の形態にかかる比較例の特性測定結果を示す図表The chart which shows the characteristic measurement result of the comparative example concerning an embodiment of the invention 空間群Ｒ３ｍ構造の構造モデルを示す図The figure which shows the structural model of space group R3m structure

Claims (7)

空間群Ｒ３ｍ構造の結晶構造を有する結晶相を備え、且つ、前記結晶相の少なくとも一部は、結晶構造における層間のサイトにナトリウム原子が存在して（００３）面の面間隔が１３．８Å以上となっているコバルト化合物。 A crystal phase having a crystal structure of a space group R3m structure, and at least part of the crystal phase has a sodium atom in a site between layers in the crystal structure , and a (003) plane spacing of 13.8 cm or more Cobalt compound. （００３）面の面間隔が１３．８Å以上となっている部分の含有量は３１．５ｗｔ％以上である請求項１記載のコバルト化合物。   2. The cobalt compound according to claim 1, wherein the content of the portion where the (003) plane spacing is 13.8 mm or more is 31.5 wt% or more. （００３）面の面間隔が１３．８Å以上となっている部分の結晶構造におけるナトリウム原子の存在しうるサイトに対する実際にナトリウム原子が存在するサイトの割合が０．３３１９以上である請求項１又は２記載のコバルト化合物。 The ratio of the sites where sodium atoms are actually present to the sites where sodium atoms can be present in the crystal structure of the portion where the spacing of the (003) plane is 13.8 cm or more is 0.3319 or more. 2. The cobalt compound according to 2. ナトリウムイオンを含む水溶液とα相の水酸化コバルトとのペースト状の混合物を酸素雰囲気下で加熱することで前記水酸化コバルトを酸化処理して得られる請求項３記載のコバルト化合物。   The cobalt compound according to claim 3, which is obtained by oxidizing the cobalt hydroxide by heating a paste-like mixture of an aqueous solution containing sodium ions and α-phase cobalt hydroxide in an oxygen atmosphere. 請求項１，２，３又は４記載のコバルト化合物と活物質とを含む電極を備えたアルカリ電池。   An alkaline battery comprising an electrode comprising the cobalt compound according to claim 1, 2, 3 or 4 and an active material. 電子伝導性のある基材に、正極活物質として水酸化ニッケルを充填するアルカリ蓄電池用正極の製造方法であって、
ナトリウムイオンを含む水溶液とα相の水酸化コバルトとを、ＣｏとＮａとの原子比（Ｎａ／Ｃｏ）が０．５以上となるように含むペースト状の混合物を６０℃以上で加熱することで前記水酸化コバルトを酸化処理し、その酸化処理によって得られた請求項１〜４のいずれか１項に記載のコバルト化合物を前記水酸化ニッケルに混合して前記電子伝導性のある基材に充填するアルカリ蓄電池用正極の製造方法。 A method for producing a positive electrode for an alkaline storage battery, wherein a base material having electron conductivity is filled with nickel hydroxide as a positive electrode active material,
By heating a paste-like mixture containing an aqueous solution containing sodium ions and α-phase cobalt hydroxide so that the atomic ratio of Co to Na (Na / Co) is 0.5 or more, at 60 ° C. or more. The cobalt hydroxide is oxidized and the cobalt compound according to any one of claims 1 to 4 obtained by the oxidation treatment is mixed with the nickel hydroxide and filled into the base material having electron conductivity. To produce a positive electrode for an alkaline storage battery. 前記ナトリウムイオンを含む水溶液と水酸化コバルトとを含む混合物を加熱する温度は１００℃以上であることを特徴とする請求項６記載のアルカリ蓄電池用正極の製造方法。   The method for producing a positive electrode for an alkaline storage battery according to claim 6, wherein a temperature at which the mixture containing the aqueous solution containing sodium ions and cobalt hydroxide is heated is 100 ° C or higher.
JP2008082239A 2008-03-26 2008-03-26 Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery Active JP5398050B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2008082239A JP5398050B2 (en) 2008-03-26 2008-03-26 Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2008082239A JP5398050B2 (en) 2008-03-26 2008-03-26 Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery

Publications (2)

Publication Number Publication Date
JP2009234846A JP2009234846A (en) 2009-10-15
JP5398050B2 true JP5398050B2 (en) 2014-01-29

Family

ID=41249284

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2008082239A Active JP5398050B2 (en) 2008-03-26 2008-03-26 Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery

Country Status (1)

Country Link
JP (1) JP5398050B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106006760B (en) * 2016-05-27 2018-01-09 湖南海纳新材料有限公司 It is a kind of to prevent method oxidized when unformed hydroxide cobalt purifies

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0017400B1 (en) * 1979-04-05 1984-05-30 United Kingdom Atomic Energy Authority Electrochemical cell and method of making ion conductors for said cell
JP3249398B2 (en) * 1996-07-03 2002-01-21 三洋電機株式会社 Non-sintered nickel electrode for alkaline storage batteries
JP3223858B2 (en) * 1996-12-24 2001-10-29 松下電器産業株式会社 Alkaline storage battery, its positive electrode active material, and method for producing the same
JP3489391B2 (en) * 1997-05-14 2004-01-19 日亜化学工業株式会社 Positive active material for lithium ion secondary battery and method for producing the same
JP3508987B2 (en) * 1997-06-26 2004-03-22 住友金属鉱山株式会社 Positive electrode active material for non-aqueous electrolyte secondary battery and its evaluation method
JP2000003707A (en) * 1998-06-16 2000-01-07 Matsushita Electric Ind Co Ltd Alkaline storage battery
JP2001110413A (en) * 1999-10-01 2001-04-20 Mitsui Mining & Smelting Co Ltd Material for positive electrode of lithium secondary battery and the lithium secondary battery using the material
JP2002220231A (en) * 2000-11-27 2002-08-09 National Institute For Materials Science Layered sodium-cobalt-manganese oxide and method of manufacturing the same
JP2002274943A (en) * 2001-03-19 2002-09-25 Tohoku Techno Arch Co Ltd Oxide thermoelectric material
JP4164652B2 (en) * 2001-11-29 2008-10-15 エスケー化研株式会社 Thermoelectric conversion material and method for producing the same
JP3867136B2 (en) * 2002-07-01 2007-01-10 独立行政法人産業技術総合研究所 Sodium cobalt oxide single crystal and method for producing the same
JP4092398B2 (en) * 2002-12-11 2008-05-28 独立行政法人産業技術総合研究所 Bulk single crystal of alkali cobalt oxide
JP4370382B2 (en) * 2004-06-14 2009-11-25 独立行政法人物質・材料研究機構 Hydrated sodium cobalt oxide
JP4997496B2 (en) * 2006-03-31 2012-08-08 独立行政法人産業技術総合研究所 Composite powder for electrode and method for producing the same
CN100424904C (en) * 2006-06-01 2008-10-08 吉林大学 Thermoelectric material of isotope battery and its preparation method

Also Published As

Publication number Publication date
JP2009234846A (en) 2009-10-15

Similar Documents

Publication Publication Date Title
JPWO2006064979A1 (en) Nickel electrode for alkaline secondary battery, method for producing the same, and alkaline secondary battery
JP2018147738A (en) Method of manufacturing separator for zinc negative electrode secondary battery and separator for zinc negative electrode secondary battery
JP5850548B2 (en) Method for producing cobalt cerium compound
JP5535684B2 (en) Hydrogen storage alloy for alkaline storage battery and hydrogen storage alloy electrode for alkaline storage battery using the same
JP4608128B2 (en) Cobalt compound, method for producing the same, positive electrode plate for alkaline storage battery and alkaline storage battery using the same
JP5495100B2 (en) Hydrogen storage alloy and nickel metal hydride storage battery
JP5783178B2 (en) Alkaline storage battery and method for producing positive electrode material for alkaline storage battery
JP2008192320A (en) Hydrogen occlusive alloy electrode, manufacturing method therefor, and alkali storage battery
JP4159161B2 (en) Positive electrode active material for alkaline storage battery, method for producing the same, and method for producing positive electrode for alkaline storage battery using the positive electrode active material
JP5398050B2 (en) Cobalt compound, alkaline battery, and method for producing positive electrode for alkaline storage battery
JP5481803B2 (en) Nickel metal hydride storage battery
JP4458725B2 (en) Alkaline storage battery
JP5743185B2 (en) Positive electrode active material for alkaline storage battery and alkaline storage battery
JP5861099B2 (en) Alloy powder for electrode, negative electrode for nickel metal hydride storage battery and nickel metal hydride storage battery using the same
JP5532389B2 (en) Hydrogen storage alloy and nickel metal hydride storage battery
WO2010004718A1 (en) Electrolytic manganese dioxide for lithium primary battery, manufacturing method therefor, and lithium primary battery using same
JP4147748B2 (en) Nickel positive electrode and nickel-hydrogen storage battery
JP5769028B2 (en) Nickel metal hydride storage battery
JP7166705B2 (en) Method for manufacturing negative electrode for zinc battery and method for manufacturing zinc battery
JP2003077468A (en) Manufacturing method of nickel electrode material
JP2008269888A (en) Nickel-hydrogen storage battery
JP3942253B2 (en) Nickel electrode active material, non-sintered nickel electrode using the same, and alkaline storage battery using the non-sintered nickel electrode
JP4436574B2 (en) Nickel electrode for alkaline storage battery and alkaline storage battery
JPH10154508A (en) Alkaline storage battery, its nickel electrode, and its manufacture
JP3619703B2 (en) Method for producing nickel electrode for alkaline storage battery

Legal Events

Date Code Title Description
A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20100507

A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20101203

RD02 Notification of acceptance of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7422

Effective date: 20101203

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20101118

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20120223

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20120228

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20120427

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20130205

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20130404

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20131008

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20131021

R150 Certificate of patent or registration of utility model

Ref document number: 5398050

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

S533 Written request for registration of change of name

Free format text: JAPANESE INTERMEDIATE CODE: R313533

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250