JPH0139192B2 - - Google Patents
Info
- Publication number
- JPH0139192B2 JPH0139192B2 JP57194090A JP19409082A JPH0139192B2 JP H0139192 B2 JPH0139192 B2 JP H0139192B2 JP 57194090 A JP57194090 A JP 57194090A JP 19409082 A JP19409082 A JP 19409082A JP H0139192 B2 JPH0139192 B2 JP H0139192B2
- Authority
- JP
- Japan
- Prior art keywords
- active material
- positive electrode
- nickel
- cobalt
- paste
- 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.)
- Expired
Links
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 48
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 40
- 229910017052 cobalt Inorganic materials 0.000 claims description 39
- 239000010941 cobalt Substances 0.000 claims description 39
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 claims description 35
- 239000011149 active material Substances 0.000 claims description 23
- 229910052759 nickel Inorganic materials 0.000 claims description 21
- 230000003647 oxidation Effects 0.000 claims description 17
- 238000007254 oxidation reaction Methods 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 239000002184 metal Substances 0.000 description 32
- 229910052751 metal Inorganic materials 0.000 description 32
- 239000007774 positive electrode material Substances 0.000 description 24
- 238000005868 electrolysis reaction Methods 0.000 description 20
- 230000004913 activation Effects 0.000 description 7
- 238000010276 construction Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- 238000003860 storage Methods 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000006104 solid solution Substances 0.000 description 5
- 229910003160 β-NiOOH Inorganic materials 0.000 description 5
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 4
- 229910021503 Cobalt(II) hydroxide Inorganic materials 0.000 description 3
- 229910002640 NiOOH Inorganic materials 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000003213 activating effect Effects 0.000 description 3
- 229910000428 cobalt oxide Inorganic materials 0.000 description 3
- ASKVAEGIVYSGNY-UHFFFAOYSA-L cobalt(ii) hydroxide Chemical compound [OH-].[OH-].[Co+2] ASKVAEGIVYSGNY-UHFFFAOYSA-L 0.000 description 3
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- OSOVKCSKTAIGGF-UHFFFAOYSA-N [Ni].OOO Chemical compound [Ni].OOO OSOVKCSKTAIGGF-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000002003 electrode paste Substances 0.000 description 2
- 229910000483 nickel oxide hydroxide Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910006279 γ-NiOOH Inorganic materials 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- 238000012369 In process control Methods 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010965 in-process control Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- QELJHCBNGDEXLD-UHFFFAOYSA-N nickel zinc Chemical compound [Ni].[Zn] QELJHCBNGDEXLD-UHFFFAOYSA-N 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、ニツケル−カドミウム蓄電池、ニツ
ケル−亜鉛蓄電池等のアルカリ蓄電池に用いるニ
ツケル正極の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a nickel positive electrode for use in alkaline storage batteries such as nickel-cadmium storage batteries and nickel-zinc storage batteries.
従来例の構成とその問題点
アルカリ蓄電池に使用するニツケル正極には、
通常多孔性ニツケル焼結基板に、電解析出法、化
学含浸法等の手段によつて、正極活物質となる水
酸化ニツケルあるいはこれにさらに水酸化コバル
ト等を充填した焼結式のニツケル正極、あるいは
ポケツト式のニツケル正極が用いられている。Conventional structure and its problems The nickel positive electrode used in alkaline storage batteries has
A sintered nickel positive electrode, in which a porous nickel sintered substrate is filled with nickel hydroxide as a positive electrode active material or cobalt hydroxide, etc., by means such as electrolytic deposition or chemical impregnation; Alternatively, a pocket-type nickel positive electrode is used.
焼結式ニツケル正極の活物質充填工程は、例え
ば化学含浸法のように、含浸工程、アルカリ処理
工程、水洗工程、乾燥工程等数多くの工程が必要
であり、所定の容量の正極板を得るためには、こ
れらの工程の数回に及ぶ繰り返しが必要となり、
一般に非常に煩雑なものとなつている。また電極
活物質を保持する焼結ニツケル基板の多孔度は、
80％程度が限界であり、従つて電極の容量密度も
それに応じた限界がある。 The active material filling process for a sintered nickel positive electrode requires a number of steps, such as an impregnation process, an alkali treatment process, a water washing process, and a drying process, such as a chemical impregnation process, in order to obtain a positive electrode plate with a predetermined capacity. requires several repetitions of these steps,
It is generally very complicated. In addition, the porosity of the sintered nickel substrate that holds the electrode active material is
The limit is about 80%, and therefore the capacitance density of the electrode has a corresponding limit.
また、金属容器に電極活物質を保持させるポケ
ツト式正極は、製造方法は簡単であるが、活物質
の利用率あるいは大電流放電特性は焼結式に比べ
劣つており、さらにその構造上の問題から、放電
特性を向上させるための薄形化あるいは小形電池
への適用は困難である。 In addition, pocket-type positive electrodes, in which the electrode active material is held in a metal container, are easy to manufacture, but are inferior to sintered-type ones in terms of active material utilization or large-current discharge characteristics, and also have structural problems. Therefore, it is difficult to make the battery thinner or to apply it to a smaller battery in order to improve the discharge characteristics.
以上のような問題から、最近では水酸化ニツケ
ルを主とするペースト状の活物質混合物を約95％
程度の多孔度を有するスポンジ状の金属ニツケル
基板に直接充填する方法や、同様な活物質混合物
をロール加圧により、開孔金属板のような導電性
支持体に塗着する方法によるニツケル正極が提案
されている。これらの正極は、従来の焼結式正極
に比べ製造が非常に簡単であること、また高い容
量密度が得られること、さらに薄形化、小形化に
適し、充放電特性も焼結式正極と同レベルである
ことなどから注目を集めている。 Due to the above problems, paste-like active material mixtures mainly composed of nickel hydroxide have recently been reduced to about 95%
A nickel positive electrode can be produced by directly filling a spongy metal nickel substrate with a certain degree of porosity, or by applying a similar active material mixture to a conductive support such as a perforated metal plate using roll pressure. Proposed. These positive electrodes are much easier to manufacture than conventional sintered positive electrodes, have higher capacity density, are suitable for thinning and miniaturization, and have charge-discharge characteristics similar to those of sintered positive electrodes. They are attracting attention because they are on the same level.
焼結式正極は、正極活物質の活性化、あるいは
極板製造時に極板中に浸入する硝酸根のような無
機塩類除去のために、アルカリ電解液中で充電、
放電を行う、いわゆる化成という工程を採つてい
る。 Sintered positive electrodes are charged in an alkaline electrolyte to activate the positive electrode active material or to remove inorganic salts such as nitrate radicals that enter the electrode plate during electrode plate manufacture.
It uses a process called chemical formation, in which electrical discharge is performed.
一方、前記のようなペーストを用いるニツケル
正極では、極板製造後に、焼結式正極と同様な方
法による化成は困難である。これはこの正極の活
物質の基板への保持状態が焼結式正極に比べて弱
いためであり、焼結式正極と同様な方法で化成を
行えば、正極中の活物質がアルカリ電解液中へ脱
落してしまうという結果になるためである。 On the other hand, in the case of a nickel positive electrode using the above-mentioned paste, it is difficult to perform chemical formation using the same method as in the case of a sintered positive electrode after manufacturing the electrode plate. This is because the retention state of the active material of this positive electrode on the substrate is weaker than that of a sintered positive electrode, and if chemical formation is performed in the same manner as the sintered positive electrode, the active material in the positive electrode will be absorbed into the alkaline electrolyte. This is because the result will be that it will fall off.
ペースト式正極は、先に述べたように、焼結式
正極に比べて数多くの利点を持つているが、上記
のような理由により極板の化成が困難であるた
め、活物質の活性化は、これまで電池構成後の充
電、放電の繰り返しによつて行つていた。しか
し、電池構成後の活性化を行う前の正極活物質の
状態は不安定であり、電池構成から充放電までの
期間、あるいは雰囲気温度などにより変化し、後
の電池特性に大きな影響を及ぼす。また、電池構
成後に正極活物質を活性化させるために行う充電
は、小電流で長時間行う必要があり、工程管理の
難しさ等工数面で問題があつた。 As mentioned earlier, paste-type positive electrodes have many advantages over sintered-type positive electrodes, but for the reasons mentioned above, it is difficult to chemically form the electrode plate, so activation of the active material is difficult. Until now, this has been done by repeating charging and discharging after battery construction. However, the state of the positive electrode active material before activation after battery construction is unstable and changes depending on the period from battery construction to charging and discharging, ambient temperature, etc., and has a large effect on subsequent battery characteristics. Furthermore, charging to activate the positive electrode active material after battery construction needs to be carried out at a small current for a long time, which poses problems in terms of man-hours such as difficulty in process control.
発明の目的
本発明は、以上のようなペーストを用いる正極
の活物質の活性化の問題を、ペースト状態で陽電
解することで解決し、特性の向上を図ることを目
的とする。OBJECTS OF THE INVENTION It is an object of the present invention to solve the problem of activating the active material of a positive electrode using a paste as described above by performing positive electrolysis in a paste state, and to improve the characteristics.
発明の構成
本発明は、水酸化ニツケル、金属ニツケル粉末
及び金属コバルト粉末を含むペースト状活物質混
合物を弱アルカリ性にして、水酸化ニツケルの酸
化電位以下でかつ金属コバルトの酸化電位以上の
電位で陽電解し、金属コバルトを電気化学的に酸
化することを特徴とする。Structure of the Invention The present invention makes a pasty active material mixture containing nickel hydroxide, nickel metal powder, and cobalt metal powder slightly alkaline, and oxidizes it at a potential below the oxidation potential of nickel hydroxide and above the oxidation potential of cobalt metal. It is characterized by electrolyzing and electrochemically oxidizing metal cobalt.
以下に本発明の原理を説明する。 The principle of the present invention will be explained below.
水酸化ニツケル、金属ニツケル、金属コバルト
からなる活物質混合物において、水酸化ニツケル
は正極の活物質、金属ニツケルは主に導電材、金
属コバルトは金属ニツケルとの相互作用によつ
て、活物質である水酸化ニツケルの充放電に寄与
し、いわゆる活物質の利用率向上に作用してい
る。 In an active material mixture consisting of nickel hydroxide, nickel metal, and cobalt metal, nickel hydroxide is the active material of the positive electrode, nickel metal is mainly a conductive material, and cobalt metal is the active material through interaction with nickel metal. It contributes to the charging and discharging of nickel hydroxide and works to improve the utilization rate of the active material.
上記正極活物質混合物をペースト状にしてスポ
ンジ状金属ニツケル基板等に充填した正極を用い
てニツケル−カドミウム蓄電池等の電池を構成
し、充電を行えば、まず金属コバルトが電気化学
的に酸化され、ひきつづき、正極活物質の水酸化
ニツケルが酸化、すなわち充電される。 When a battery such as a nickel-cadmium storage battery is constructed using a positive electrode made of the above positive electrode active material mixture in the form of a paste and filled in a sponge-like metallic nickel substrate, etc., and charged, the metallic cobalt is electrochemically oxidized, Subsequently, the nickel hydroxide of the positive electrode active material is oxidized, that is, charged.
水酸化ニツケルの正極活物質としての利用率
は、その充電状態あるいは放電状態の結晶形によ
り異なる。充電状態にあるオキシ水酸化ニツケル
の形態にはβ−NiOOHとγ−NiOOHの２種類
があることが知られており、γ−NiOOHは充放
電の可逆性が悪く、利用率が低い。一方β−
NiOOHは利用率が高く、水酸化ニツケルとコバ
ルトが固溶体で存在すると、充電状態のβ−
NiOOHが安定化することも知られている。また
充電状態の正極中に存在するオキシ水酸化ニツケ
ルのγ、βの結晶形の比率は、正極中の金属コバ
ルトの比率、金属ニツケルの比率に大きく影響さ
れる。さらに水酸化ニツケルとコバルトが固溶体
化されていると結晶格子欠陥を増大させることが
でき、結晶中でのプロトン（H+）の移動性を高
め、利用率を向上させることができる。 The utilization rate of nickel hydroxide as a positive electrode active material varies depending on its crystal form in its charged or discharged state. It is known that there are two types of nickel oxyhydroxide in a charged state: β-NiOOH and γ-NiOOH, and γ-NiOOH has poor charge/discharge reversibility and low utilization rate. On the other hand, β−
NiOOH has a high utilization rate, and when nickel hydroxide and cobalt exist in solid solution, the charged state β-
It is also known that NiOOH is stabilized. Further, the ratio of the γ and β crystal forms of nickel oxyhydroxide present in the positive electrode in a charged state is greatly influenced by the ratio of metallic cobalt and the ratio of metallic nickel in the positive electrode. Furthermore, when nickel hydroxide and cobalt are made into a solid solution, crystal lattice defects can be increased, the mobility of protons (H + ) in the crystal can be increased, and the utilization rate can be improved.
金属コバルトを電気化学的に酸化（陽電解）す
ると、水酸化コバルトあるいは酸化コバルトに変
換するが、この際コバルトの一部がイオン化し、
イオン化したコバルトは水酸化ニツケルの結晶格
子中に侵入して水酸化ニツケルとの固溶体を形成
すると考えられる。 When metal cobalt is electrochemically oxidized (positive electrolysis), it is converted to cobalt hydroxide or cobalt oxide, but at this time, some of the cobalt is ionized,
It is believed that ionized cobalt penetrates into the crystal lattice of nickel hydroxide and forms a solid solution with nickel hydroxide.
しかし酸化電位が高すぎる場合は、金属コバル
トが一気に酸化され、安定な酸化コバルトとなる
ため、前記のコバルトのイオン化、水酸化ニツケ
ルとの固溶体化の効果は乏しくなると推定され
る。 However, if the oxidation potential is too high, metallic cobalt is oxidized all at once and becomes stable cobalt oxide, so it is estimated that the effects of ionizing cobalt and forming it into a solid solution with nickel hydroxide will be poor.
金属コバルトを水酸化ニツケルの酸化電位以下
の電位で徐々に酸化する場合、コバルトの比率が
多い程、水酸化ニツケルはコバルトリツチ（コバ
ルトの侵入量が多くなる）となり、β−NiOOH
をより安定化させる。又金属ニツケルは導電性を
確保し、電解時の電流分布を均一にし、さらにペ
ースト中の抵抗を低減するため、金属コバルト酸
化時の過電圧が低下し、コバルトのイオン化を促
進すると推定される。逆に金属ニツケル量が少な
い場合は、部分的に電流が集中し、金属コバルト
を安定な酸化コバルトに変換してしまい利用率向
上には寄与しなくなる。 When metal cobalt is gradually oxidized at a potential lower than the oxidation potential of nickel hydroxide, the higher the proportion of cobalt, the more cobalt-rich the nickel hydroxide becomes (increasing the amount of cobalt intruded into β-NiOOH).
to make it more stable. Furthermore, since metallic nickel ensures conductivity, makes the current distribution uniform during electrolysis, and further reduces the resistance in the paste, it is presumed that the overvoltage during oxidation of metallic cobalt decreases and promotes the ionization of cobalt. Conversely, if the amount of metallic nickel is small, the current will concentrate locally, converting metallic cobalt into stable cobalt oxide, and will not contribute to improving the utilization rate.
これらより、金属ニツケル量が多くなるとβ−
NiOOHが安定化するため、β−NiOOHの比率
が増加すると考えられる。しかしコバルトが酸化
して水酸化ニツケルと固溶体化していない場合に
は利用率向上への寄与は小さいと考えられる。 From these, when the amount of metallic nickel increases, β-
It is thought that the ratio of β-NiOOH increases because NiOOH is stabilized. However, if cobalt is not oxidized and becomes a solid solution with nickel hydroxide, its contribution to improving the utilization rate is considered to be small.
以上のことから、正極活物質である水酸化ニツ
ケルの利用率を向上させるためには、水酸化ニツ
ケル、金属ニツケル、金属コバルトの３成分が共
存する状態で、金属コバルトを電気化学的に酸化
することによつて、水酸化ニツケルの結晶形を利
用率の高いβ−NiOOHに変化させるのが有効で
あるものと思われる。 Based on the above, in order to improve the utilization rate of nickel hydroxide, which is a positive electrode active material, it is necessary to electrochemically oxidize metal cobalt in a state where the three components of nickel hydroxide, metal nickel, and metal cobalt coexist. In particular, it may be effective to change the crystal form of nickel hydroxide to β-NiOOH, which has a high utilization rate.
しかし、先に述べた通り、充電前の水酸化ニツ
ケル、金属コバルト、金属ニツケルの３成分の状
態は不安定であり、活性化を行うための充電々流
が大きい場合は、第１図に示すように水酸化ニツ
ケルの最終的な利用率が極端に低下する。第１図
は0.05C〜1C相当の電流で電池容量の160％の電
気量を充電したときの充電々流と活物質利用率の
関係を示す。これは、正極活物質利用率の向上に
寄与する金属コバルトが大電流の充電によりアル
カリ中に溶出するか、あるいは活物質利用率向上
に寄与しない高次の酸化物に変化するためである
と思われる。従つて、正極活物質活性化のための
充電は、小電流で行わなければならない。 However, as mentioned earlier, the state of the three components of nickel hydroxide, cobalt metal, and nickel metal before charging is unstable, and if the charging current for activation is large, the state shown in Figure 1 As a result, the final utilization rate of nickel hydroxide is extremely reduced. Figure 1 shows the relationship between charging current and active material utilization rate when charging 160% of the battery capacity with a current equivalent to 0.05C to 1C. This is thought to be because the metal cobalt, which contributes to improving the positive electrode active material utilization rate, is eluted into the alkali due to high current charging, or it is changed into a higher-order oxide that does not contribute to the improvement of the active material utilization rate. It will be done. Therefore, charging for activating the positive electrode active material must be performed with a small current.
従来は、正極活物質活性化のために行う電池構
成後の初充電は、0.05C〜0.1C相当の電流で行い、
充電時間は15〜30時間を要し、電池製造工程の時
間短縮化の面で問題があつた。 Conventionally, the initial charge after battery configuration to activate the positive electrode active material was performed with a current equivalent to 0.05C to 0.1C.
Charging time required 15 to 30 hours, which posed a problem in terms of shortening the battery manufacturing process.
活物質活性化のための電気化学的なコバルトの
酸化は、必ずしも電池構成後でなくてもよいと思
われる。例えば、極板構成後アルカリ電解液中で
陽電解してもよいわけであるが、このような化成
では、後にも述べたように、極板からの活物質の
脱落が激しく、困難である。 It appears that electrochemical cobalt oxidation for active material activation does not necessarily have to occur after cell construction. For example, positive electrolysis may be performed in an alkaline electrolyte after forming the electrode plate, but such chemical formation is difficult because, as mentioned later, the active material falls off from the electrode plate considerably.
そこで、本発明者らは、正極活物質混合物のペ
ースト製造時の化成による、活物質の活性化の可
能性について検討した。水酸化ニツケル、金属コ
バルト、金属ニツケルからなる正極活物質混合物
の活性化は、先にも述べたように、前記３成分が
共存する状態で金属コバルトを徐々に電気化学的
に酸化させることによつて達成される。これは、
正極活物質が、電池内の極板中の状態でも、ある
いは極板構成前のペーストの状態でも同様である
と思われる。従つて正極活物質ペースト中の金属
コバルトを電気化学的に酸化すれば、正極活物質
の活性化が達成されるはずである。 Therefore, the present inventors investigated the possibility of activating the active material by chemical conversion during paste production of the positive electrode active material mixture. As mentioned earlier, the positive electrode active material mixture consisting of nickel hydroxide, cobalt metal, and nickel metal is activated by gradually electrochemically oxidizing the cobalt metal in the coexistence of the three components. It will be achieved. this is,
This seems to be the case whether the positive electrode active material is in the state of an electrode plate in a battery or in the state of a paste before forming an electrode plate. Therefore, activation of the positive electrode active material should be achieved by electrochemically oxidizing the metal cobalt in the positive electrode active material paste.
第２図は使用した電解装置を示す。１はペース
ト電解用の電源、２はマイナス電極を兼ねる金属
容器、３はプラス電極、４はペースト５とマイナ
ス電極２を隔離する多孔性の電解隔膜である。ま
た、６はペースト５から隔膜４を通して流出する
水溶液である。ペースト５を電解が容易になるよ
うに弱アルカリ性にして電解を行うと、ペースト
中の成分が電気化学的に酸化される。酸化の順序
は、最も酸化を受けやすいペースト中の金属コバ
ルトから始まり、次に水酸化ニツケルの酸化が進
行する。正極板は、電池構成時において、放電状
態すなわち水酸化ニツケルが酸化を受けていない
状態にあることが必要である。従つて、ペースト
化成時には、金属コバルトのみが酸化され、水酸
化ニツケルは酸化を受けない状態にある必要があ
る。 Figure 2 shows the electrolyzer used. 1 is a power source for paste electrolysis, 2 is a metal container that also serves as a negative electrode, 3 is a positive electrode, and 4 is a porous electrolytic diaphragm that isolates the paste 5 and the negative electrode 2. Further, 6 is an aqueous solution flowing out from the paste 5 through the diaphragm 4. When the paste 5 is made weakly alkaline to facilitate electrolysis and electrolysis is performed, components in the paste are electrochemically oxidized. The oxidation sequence begins with the metal cobalt in the paste, which is most susceptible to oxidation, followed by oxidation of the nickel hydroxide. The positive electrode plate must be in a discharged state, that is, in a state in which nickel hydroxide is not oxidized, during battery construction. Therefore, during paste formation, only the metal cobalt must be oxidized and the nickel hydroxide must be in a state where it is not oxidized.
このことからペーストの化成は、プラス側すな
わちペースト側の電位が、コバルトの酸化電位以
上で水酸化コバルトの酸化電位以下の間にあるこ
とが必要である。このような電解を行うために
は、理想的には、ペースト側の電位を一定にした
定電位電解が必要であるが、簡易的には、プラス
極、マイナス極間の電圧を一定にした同電圧電解
で行うことができる。 For this reason, in forming the paste, the potential on the positive side, that is, on the paste side, must be between the oxidation potential of cobalt or more and the oxidation potential of cobalt hydroxide or less. In order to carry out such electrolysis, ideally constant potential electrolysis with a constant potential on the paste side is required, but it is simpler to use constant potential electrolysis with a constant voltage between the positive and negative electrodes. This can be done by voltage electrolysis.
本発明者らは以上のような原理にもとづき、正
極ペーストの定電圧定電流電解を行い、正極ペー
スト、すなわち正極活物質の活性化を試みたとこ
ろ、ペースト中の金属コバルトのみが電気化学的
に酸化され、またこのようにして製造した正極活
物質は、電池内で活性化した場合と同様に、活性
化され、水酸化ニツケルの電極活物質としての利
用率も非常に高いものになることを見出した。 Based on the above principle, the present inventors tried to activate the positive electrode paste, that is, the positive electrode active material, by electrolyzing the positive electrode paste at constant voltage and constant current, and found that only the metallic cobalt in the paste was electrochemically activated. The positive electrode active material produced in this way is activated in the same way as when activated in a battery, and the utilization rate of nickel hydroxide as an electrode active material is also very high. I found it.
実施例の説明
正極活物質混合物としては、水酸化ニツケル、
金属コバルト、金属ニツケルを重量比率で100：
５：18の割合で混合したものを用い、水、及びカ
ルボキシメチルセルロースを加え、練合してペー
スト状態とした。Description of Examples The positive electrode active material mixture includes nickel hydroxide,
Cobalt metal, nickel metal weight ratio: 100:
Using a mixture at a ratio of 5:18, water and carboxymethylcellulose were added and kneaded to form a paste.
電解装置としては、第２図に示したものを用い
た。ペーストのPHは７〜８の弱アルカリ性であつ
たが、電解が容易になるように水酸化ナトリウム
水溶液を加えてPHを９〜10に調整した。電気槽の
電極２，３は金属ニツケルとし、隔膜４はナイロ
ンの不織布を用いた。 The electrolyzer shown in FIG. 2 was used. The paste had a slightly alkaline pH of 7 to 8, but the pH was adjusted to 9 to 10 by adding an aqueous sodium hydroxide solution to facilitate electrolysis. The electrodes 2 and 3 of the electric bath were made of nickel metal, and the diaphragm 4 was made of nylon nonwoven fabric.
電解は20℃の雰囲気で行つた。先に述べた通
り、金属コバルトの電解酸化は、大電流で行うこ
とができず、またプラス極の電位は、水酸化ニツ
ケルの酸化電位以下にすることが必要であるた
め、電解は、定電圧、定電流で行つた。このよう
な電解を行えば、初期は定電流で、金属コバルト
の酸化が徐々に進行して電解電圧が上昇し、ひき
つづき定電圧電解となつて残存する金属コバルト
がすべて酸化される。定電流部分は、電池内での
正極活物質活性化のときの電流値（0.1C）から換
算し、ペースト1CC当り50ｍＡとし、定電圧部分
は、プラス極の電位が水酸化ニツケルの酸化電位
以下となるようにCd／CdO極基準で1.4V以下と
なるように設定した。 Electrolysis was performed in an atmosphere at 20°C. As mentioned earlier, electrolytic oxidation of metallic cobalt cannot be performed with a large current, and the potential of the positive electrode must be lower than the oxidation potential of nickel hydroxide. Therefore, electrolysis is carried out at a constant voltage. , carried out at constant current. When such electrolysis is performed, the current is initially constant, and as the oxidation of metal cobalt gradually progresses, the electrolytic voltage increases, and then constant voltage electrolysis is performed, and all remaining metal cobalt is oxidized. The constant current part is calculated from the current value (0.1C) when the positive electrode active material is activated in the battery, and is 50 mA per 1CC of paste, and the constant voltage part is when the potential of the positive electrode is below the oxidation potential of nickel hydroxide. The voltage was set to 1.4V or less based on the Cd/CdO pole.
以上のような条件で電解した結果、約２時間の
間定電流で電解が進み、ついで定電圧の電解に入
り、電解電流が徐々に低下し、約２時間後に電流
が０となつた。 As a result of electrolysis under the above conditions, electrolysis proceeded at a constant current for about 2 hours, then constant voltage electrolysis started, the electrolytic current gradually decreased, and the current became 0 after about 2 hours.
以上のようにして電解したペーストを、多孔度
95％のスポンジ状ニツケル基板に充填し、正極に
加工し、1500ｍAh相当の密閉ニツケル−カドミ
ウム蓄電池を構成した。このようにして製作した
電池は、正極活物質が活性化され、かつ安定して
いるため、従来法により製作した電池に見られた
ような構成後の電池放置時の温度あるいは期間に
より電池特性が変動するような現象もなく、正極
活物質である水酸化ニツケルの利用率も電池内で
活物質を活性化したものと同等のレベルにあつ
た。 The paste electrolyzed in the above manner is
A 95% sponge-like nickel substrate was filled with the material, processed into a positive electrode, and a sealed nickel-cadmium storage battery with a capacity of 1,500 mAh was constructed. In batteries manufactured in this way, the positive electrode active material is activated and stable, so the battery characteristics may vary depending on the temperature or period of time when the battery is left after construction, which is the case with batteries manufactured using conventional methods. There were no fluctuation phenomena, and the utilization rate of nickel hydroxide, the positive electrode active material, was at the same level as when the active material was activated within the battery.
また、従来法による電池は、先にも述べた通り
活物質利用等の低下があるため、初期段階での大
電流の充電ができなかつたのに対し、本発明によ
るものは、初期段階で大電流充電をしても活物質
利用率低下の現象も見られず、優れた特性を示し
た。 In addition, as mentioned above, batteries made using the conventional method could not be charged with a large current in the initial stage due to a decline in the utilization of active materials, etc., whereas the battery according to the present invention could not be charged with a large current in the initial stage. Even with current charging, no decrease in active material utilization was observed, and excellent characteristics were exhibited.
発明の効果
以上のように、本発明によれば、正極活物質の
活性化、すなわち水酸化ニツケルのβ−NiOOH
への転換をペースト状態で多量に一度に行えるた
め、従来の電池内での活性化に比べ工程上非常に
効率のよいものとなる。また、電池の構成後の状
態が従来のものに比べて安定であり、初期から大
電流の充電が可能になる等、多くの利点を有する
ものである。Effects of the Invention As described above, according to the present invention, activation of a positive electrode active material, that is, β-NiOOH of nickel hydroxide
Because it is possible to convert a large amount at once in a paste state, the process is much more efficient than conventional activation within a battery. In addition, the battery has many advantages, such as being more stable than conventional batteries and being able to charge with a large current from the beginning.
第１図はペースト式正極を用いた密閉形ニツケ
ル−カドミウム電池の初期の充電々流値と、水酸
化ニツケル活物質利用率との関係を示す図、第２
図は正極活物質の電解装置の略図である。
１……電解用電源、２……マイナス極を兼ねる
金属容器、３……プラス極、４……電解隔膜、５
……正極活物質ペースト。
Figure 1 shows the relationship between the initial charging current value of a sealed nickel-cadmium battery using a paste type positive electrode and the utilization rate of nickel hydroxide active material.
The figure is a schematic diagram of an electrolyzer for positive electrode active material. 1... Power source for electrolysis, 2... Metal container that also serves as a negative electrode, 3... Positive electrode, 4... Electrolytic diaphragm, 5
...Cathode active material paste.
Claims (1)
ケルを含む弱アルカリ性の活物質混合物ペースト
を水酸化ニツケルの酸化電位以下で、かつ金属コ
バルトの酸化電位以上の電位で陽電解する工程を
有するニツケル正極の製造法。1. A method for producing a nickel positive electrode comprising the step of positively electrolyzing a weakly alkaline active material mixture paste containing nickel hydroxide, metallic cobalt, and metallic nickel at a potential below the oxidation potential of nickel hydroxide and above the oxidation potential of metallic cobalt. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57194090A JPS5983348A (en) | 1982-11-04 | 1982-11-04 | Manufacture of nickel positive electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57194090A JPS5983348A (en) | 1982-11-04 | 1982-11-04 | Manufacture of nickel positive electrode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5983348A JPS5983348A (en) | 1984-05-14 |
| JPH0139192B2 true JPH0139192B2 (en) | 1989-08-18 |
Family
ID=16318780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57194090A Granted JPS5983348A (en) | 1982-11-04 | 1982-11-04 | Manufacture of nickel positive electrode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5983348A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS601759A (en) * | 1983-06-17 | 1985-01-07 | Japan Storage Battery Co Ltd | Alkaline storage battery |
| DE69232392T2 (en) * | 1991-10-21 | 2002-08-29 | Yuasa Battery Co Ltd | METHOD FOR PRODUCING A NICKEL PLATE AND AN ALKALINE BATTERY |
-
1982
- 1982-11-04 JP JP57194090A patent/JPS5983348A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5983348A (en) | 1984-05-14 |
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