JP2008084736A - Non-sintered positive electrode for alkaline storage battery - Google Patents

Non-sintered positive electrode for alkaline storage battery Download PDF

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JP2008084736A
JP2008084736A JP2006264608A JP2006264608A JP2008084736A JP 2008084736 A JP2008084736 A JP 2008084736A JP 2006264608 A JP2006264608 A JP 2006264608A JP 2006264608 A JP2006264608 A JP 2006264608A JP 2008084736 A JP2008084736 A JP 2008084736A
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positive electrode
alkaline storage
storage battery
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Takeshi Ito
武 伊藤
Takayuki Yano
尊之 矢野
Naoyasu Nomura
直靖 野村
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Sanyo Electric Co Ltd
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    • 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
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    • Y02E60/10—Energy storage using batteries

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-sintered positive electrode for alkaline storage battery, with which deterioration of battery capacity due to standing in overdischarge state and high temperatures can be suppressed, without causing significant increase in the concentration of Na and Li in the alkaline electrolytic solution. <P>SOLUTION: The non-sintered positive electrode 3 for alkaline storage battery contains active material particles 14, having a nickel hydroxide based compound as a principle component and complex oxide particles 15, having a composition as expressed by general Formula: LiNi<SB>x</SB>Co<SB>y</SB>Mn<SB>z</SB>O<SB>2</SB>(where x, y, and z satisfy the relations 0<x<1, 0<y<1, 0<z<1, and x+y+z=1). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明はアルカリ蓄電池用の非焼結式正極に関する。   The present invention relates to a non-sintered positive electrode for an alkaline storage battery.

電動工具等に非焼結式正極を含むアルカリ蓄電池を使用した場合、高温下あるいは過放電されるような使用条件下での電池のサイクル寿命が、焼結式正極を使用した場合に比べて顕著に劣る。このようなサイクル寿命の低下の要因の一つとして、高温下あるいは過放電時の正極容量低下が挙げられる。
正極容量低下を抑制するための一般的な手段として、アルカリ電解液中のナトリウム又はリチウム濃度を増大することが挙げられるが、そのトレードオフとして、リチウムリッチなアルカリ電解液は、負極腐食を促進してサイクル寿命や高率放電特性の低下をもたらす。 When alkaline storage batteries containing non-sintered positive electrodes are used for power tools, etc., the cycle life of batteries under high-temperature or over-discharged conditions is significantly higher than when using sintered positive electrodes Inferior to One of the causes of such a decrease in cycle life is a decrease in positive electrode capacity at high temperatures or during overdischarge.
As a general means for suppressing the decrease in positive electrode capacity, it is possible to increase the concentration of sodium or lithium in the alkaline electrolyte. As a trade-off, lithium-rich alkaline electrolyte promotes negative electrode corrosion. As a result, cycle life and high-rate discharge characteristics are degraded.

一方、特許文献１が開示するアルカリ蓄電池の正極は、ニッケル水酸化物と、リチウムとコバルトの複合酸化物とを含み、具体的には、複合酸化物は一般式LiｘCoO２（但しｘは0.2〜0.9）で表される。特許文献１によれば、このアルカリ蓄電池は、深放電状態になっても、その後回復充電がなされ、再度放電されたときに初期と同等な正極活物質利用率が得られ、深放電特性に優れ、容量低下が少なく長寿命である。 On the other hand, the positive electrode of the alkaline storage battery disclosed in Patent Document 1 includes nickel hydroxide and a composite oxide of lithium and cobalt. Specifically, the composite oxide has a general formula Li x CoO 2 (where x is 0.2-0.9). According to Patent Document 1, even when this alkaline storage battery is in a deep discharge state, recovery charge is performed thereafter, and when it is discharged again, a positive electrode active material utilization rate equivalent to the initial stage is obtained, and the deep discharge characteristics are excellent. Long life with little decrease in capacity.

特許文献２が開示するアルカリ蓄電池の正極は、水酸化ニッケルを主とする活物質と所定の混合物とを含み、混合物の量は水酸化ニッケルの総量の5〜30重量％である。混合物は、一般式：MｘCoO２（ｘは0＜ｘ≦1，MはLi，Na，Kのうち少なくとも１種の元素）で示されるコバルト複合化合物と、２価を超える原子価を有する酸化ニッケル化合物及び３価を超える原子価を有する酸化マンガン化合物のうち一方又は両方とからなる。特許文献１によれば、このアルカリ蓄電池は、高温状態での過放電においても優れた容量回復率を有する。 The positive electrode of the alkaline storage battery disclosed in Patent Document 2 includes an active material mainly composed of nickel hydroxide and a predetermined mixture, and the amount of the mixture is 5 to 30% by weight of the total amount of nickel hydroxide. The mixture has a cobalt composite compound represented by the general formula: M x CoO 2 (x is 0 <x ≦ 1, M is at least one element selected from Li, Na, and K) and a valence of more than two valences. It consists of one or both of a nickel oxide compound and a manganese oxide compound having a valence exceeding three. According to Patent Document 1, this alkaline storage battery has an excellent capacity recovery rate even during overdischarge in a high temperature state.

特許文献３が開示するアルカリ二次電池の非焼結ニッケル電極は、部分的にβ構造のオキシ水酸化ニッケルに酸化されたニッケルを主体とする水酸化物の粒子を含み、この粒子はニッケル及びコバルトのリチオ酸化物で少なくとも部分的に被覆される。具体的には、リチオ酸化物の組成は、式LiｘNiｙCo１―ｙO２（式中、0.1≦ｘ≦1且つ0＜ｙ≦0.9である）により表される。特許文献２によれば、このアルカリ二次電池は、放電状態で長期保存したとき、容量の不可逆的損失が低減される。
特開平11-149921号公報（特許請求の範囲、発明の効果等） 特許第3414200号公報（特許請求の範囲、発明の効果等） 特開2001-202957号公報（特許請求の範囲、表１等） The non-sintered nickel electrode of the alkaline secondary battery disclosed in Patent Document 3 includes hydroxide particles mainly composed of nickel oxidized into nickel oxyhydroxide having a β structure. It is at least partially coated with cobalt lithioxide. Specifically, the composition of the lithio oxide is represented by the formula Li x Ni y Co 1-y O 2 (where 0.1 ≦ x ≦ 1 and 0 <y ≦ 0.9). According to Patent Document 2, when the alkaline secondary battery is stored in a discharged state for a long time, the irreversible loss of capacity is reduced.
Japanese Patent Laid-Open No. 11-149921 (claims, effects of the invention, etc.) Japanese Patent No. 3414200 (claims, effects of the invention, etc.) JP 2001-202957 A (Claims, Table 1 etc.)

しかしながら、特許文献１乃至３の電池にあっても、電池を放電状態や高温下で放置すると、負極からの溶出物等により、正極の導電性マトリックスを形成する複合酸化物、コバルト複合化合物又はリチオ酸化物中のコバルトは化学的に少なからず還元される。このため、導電性マトリックスのコバルトが還元をうけることによる電池容量低下については、未だ改善の余地がある。   However, even in the batteries of Patent Documents 1 to 3, when the battery is left in a discharged state or at a high temperature, a composite oxide, a cobalt composite compound, or a lithium ion that forms a conductive matrix of the positive electrode due to an effluent from the negative electrode or the like. Cobalt in the oxide is chemically reduced. For this reason, there is still room for improvement in battery capacity reduction due to reduction of cobalt in the conductive matrix.

本発明は上述の事情に基づいてなされたもので、その目的とするところは、アルカリ電解液中のNaやLiの濃度を増大させることなく、過放電状態や高温下での放置による電池容量低下が抑制される、アルカリ蓄電池用の非焼結式正極を提供することにある。   The present invention has been made based on the above circumstances, and its purpose is to reduce battery capacity due to overdischarge and high temperature standing without increasing the concentration of Na and Li in the alkaline electrolyte. Is to provide a non-sintered positive electrode for an alkaline storage battery.

上記の目的を達成すべく、本発明によれば、水酸化ニッケル系化合物を主成分とする活物質粒子と、一般式：LiNiｘCoｙMnｚO２（ただし式中、ｘ，ｙ及びｚは、0＜x＜1，0＜y＜1，0＜z＜1，x+y+z=1で示される関係を満たす）で示される組成を有する複合酸化物粒子とを含むことを特徴とするアルカリ蓄電池用の非焼結式正極が提供される（請求項１）。 In order to achieve the above object, according to the present invention, active material particles mainly composed of a nickel hydroxide compound and a general formula: LiNi x Co y Mn z O 2 (wherein x, y and z And 0 <x <1, 0 <y <1, 0 <z <1, satisfying the relationship represented by x + y + z = 1) and a composite oxide particle having a composition represented by A non-sintered positive electrode for an alkaline storage battery is provided.

好ましくは、非焼結式正極は、記活物質粒子に含まれる前記水酸化ニッケル系化合物100質量部に対し、１質量部以上10質量部以下の範囲の前記複合酸化物粒子を含む（請求項２）。
好ましくは、非焼結式正極は、前記活物質粒子の少なくとも一部を覆う被覆層を更に含み、前記被覆層は、コバルト化合物を主成分として含む（請求項３）。 Preferably, the non-sintered positive electrode includes the composite oxide particles in a range of 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the nickel hydroxide compound contained in the active material particles. 2).
Preferably, the non-sintered positive electrode further includes a coating layer covering at least a part of the active material particles, and the coating layer contains a cobalt compound as a main component (Claim 3).

本発明の請求項１のアルカリ蓄電池用の非焼結式正極は複合酸化物粒子を含み、複合酸化物粒子の組成は、一般式：LiNiｘCoｙMnｚO２（ただし式中、ｘ，ｙ及びｚは、0＜x＜1，0＜y＜1，0＜z＜1，x+y+z=1で示される関係を満たす）で示される。この複合酸化物粒子は、従来の複合酸化物、コバルト複合化合物又はリチオ酸化物に比べて耐還元性に優れている。このため、この非焼結式正極を適用したアルカリ蓄電池を過放電状態や高温下で放置したとき、導電性マトリックスとしての複合酸化物中のコバルトの還元が抑制され、放置後の電池容量の低下が大幅に抑制される。つまり、この非焼結式正極を適用したアルカリ蓄電池にあっては、過放電状態や高温下での放置後にも、導電性マトリックスが良好な導電性を有しているため活物質の利用率が高く、容量低下が少ない。 The non-sintered positive electrode for an alkaline storage battery according to claim 1 of the present invention includes composite oxide particles, and the composition of the composite oxide particles is a general formula: LiNi x Co y Mn z O 2 (where, x, and y and z satisfy the relationship represented by 0 <x <1, 0 <y <1, 0 <z <1, x + y + z = 1). The composite oxide particles are excellent in reduction resistance compared to conventional composite oxides, cobalt composite compounds, or lithio oxides. For this reason, when an alkaline storage battery to which this non-sintered positive electrode is applied is left in an overdischarged state or at a high temperature, the reduction of cobalt in the composite oxide as a conductive matrix is suppressed, and the battery capacity after being left is reduced. Is greatly suppressed. In other words, in an alkaline storage battery to which this non-sintered positive electrode is applied, the utilization rate of the active material is high because the conductive matrix has good conductivity even after being left in an overdischarged state or at a high temperature. High and little capacity loss.

請求項２のアルカリ蓄電池用の非焼結式正極では、100質量部の水酸化ニッケル系化合物に対し、１質量部以上10質量部以下の範囲の複合酸化物を含むことで、複合酸化物粒子が導電性に優れた導電性マトリックスを形成しながら、活物質量が十分に確保される。
請求項３のアルカリ蓄電池用の非焼結式正極では、活物質粒子の少なくとも一部がコバルト化合物の被覆層で覆われることで、導電性においてより優れた導電性マトリックスが形成される。 The non-sintered positive electrode for an alkaline storage battery according to claim 2, wherein the composite oxide particles include a composite oxide in a range of 1 part by weight to 10 parts by weight with respect to 100 parts by weight of the nickel hydroxide compound. However, the amount of active material is sufficiently secured while forming a conductive matrix having excellent conductivity.
In the non-sintered positive electrode for an alkaline storage battery according to claim 3, at least a part of the active material particles is covered with a coating layer of a cobalt compound, thereby forming a conductive matrix that is more excellent in conductivity.

図１は、本発明の一実施形態に係るアルカリ蓄電池用の非焼結式正極（ニッケル電極）が正極３として用いられたニッケル水素二次電池を示す。
電池は、有底円筒形状の外装缶１を備え、外装缶１の中に電極群２が収容されている。電極群２は、正極３及び負極４を、セパレータ５を介して渦巻状に巻回してなり、電極群２の最外周には、その渦巻き方向でみて負極４の外端側の部位が配置され、負極４が外装缶１の内周壁と電気的に接続されている。また、外装缶１の中には、図示しないアルカリ電解液が収容され、アルカリ電解液としては、例えば水酸化カリウム水溶液と、水酸化ナトリウム水溶液や水酸化リチウム水溶液などとを混合したものを用いることができる。 FIG. 1 shows a nickel-hydrogen secondary battery in which a non-sintered positive electrode (nickel electrode) for an alkaline storage battery according to an embodiment of the present invention is used as a positive electrode 3.
The battery includes a bottomed cylindrical outer can 1, and an electrode group 2 is accommodated in the outer can 1. The electrode group 2 is formed by winding a positive electrode 3 and a negative electrode 4 in a spiral shape with a separator 5 interposed therebetween, and a portion on the outer end side of the negative electrode 4 is disposed on the outermost periphery of the electrode group 2 when viewed in the spiral direction. The negative electrode 4 is electrically connected to the inner peripheral wall of the outer can 1. The outer can 1 contains an alkaline electrolyte (not shown). As the alkaline electrolyte, for example, a mixture of a potassium hydroxide aqueous solution and a sodium hydroxide aqueous solution or a lithium hydroxide aqueous solution is used. Can do.

外装缶１の開口内には、リング状の絶縁性ガスケット６を介して、中央にガス抜き孔７を有する円形の蓋板８が配置されている。これら絶縁性ガスケット６及び蓋板８は、かしめ加工された外装缶１の開口縁によって固定されている。電極群２の正極３と蓋板８の内面との間には、これらの間を電気的に接続する正極リード９が配置されている。一方、蓋板８の外面には、ガス抜き孔７を閉塞するようにゴム製の弁体10が配置され、更に、弁体10を囲むようにフランジ付きの円筒形状の正極端子11が取り付けられている。   A circular lid plate 8 having a gas vent hole 7 in the center is disposed in the opening of the outer can 1 via a ring-shaped insulating gasket 6. The insulating gasket 6 and the cover plate 8 are fixed by the opening edge of the caulked outer can 1. Between the positive electrode 3 of the electrode group 2 and the inner surface of the cover plate 8, a positive electrode lead 9 that electrically connects them is disposed. On the other hand, a rubber valve body 10 is disposed on the outer surface of the cover plate 8 so as to close the gas vent hole 7, and a cylindrical positive electrode terminal 11 with a flange is attached so as to surround the valve body 10. ing.

また、外装缶１の開口縁上には環状の絶縁板12が配置され、正極端子11は絶縁板12を貫通して突出している。符号13は、外装チューブに付されており、外装チューブ13は絶縁板12の周縁、外装缶１の外周面及び底壁周縁を被覆している。
電極群２の負極４は（水素吸蔵合金電極）は、導電性の負極基板と、負極基板に保持された負極合剤とからなり、負極基板としては、例えば、パンチングメタルを用いることができる。 An annular insulating plate 12 is disposed on the opening edge of the outer can 1, and the positive terminal 11 projects through the insulating plate 12. Reference numeral 13 is attached to the outer tube, and the outer tube 13 covers the periphery of the insulating plate 12, the outer peripheral surface of the outer can 1 and the periphery of the bottom wall.
The negative electrode 4 (hydrogen storage alloy electrode) of the electrode group 2 is composed of a conductive negative electrode substrate and a negative electrode mixture held on the negative electrode substrate. As the negative electrode substrate, for example, punching metal can be used.

負極合剤は、水素吸蔵合金粉末、結着剤、及び必要に応じて導電剤からなり、水素吸蔵合金粉末としては、例えば、結晶構造がAB５型のものや、AB５型とAB２型とを併せたような超格子型のものを用いることができる。結着剤としては、例えば、カルボキシメチルセルロース、メチルセルロース、PTFEディスパージョン、HPC、ポリアクリル酸ナトリウムなどを単独若しくは混合して用いることができる。また、導電剤としては、例えばカーボン粉末などを用いることができる。 The negative electrode mixture, the hydrogen storage alloy powder, a binder, and made of a conductive agent, if necessary, as the hydrogen-absorbing alloy powder, for example, those crystal structure of AB 5 type and, AB 5 type and AB 2 type And a superlattice type in combination with the above. As the binder, for example, carboxymethyl cellulose, methyl cellulose, PTFE dispersion, HPC, sodium polyacrylate and the like can be used alone or in combination. In addition, as the conductive agent, for example, carbon powder can be used.

負極４は、水素吸蔵合金粉末、結着剤、水、及び必要に応じて配合される導電剤から成る負極用スラリを調整し、負極スラリが塗着された負極基板を、乾燥を経てから圧延・裁断して作製することができる。
以下、本発明の一実施形態に係るアルカリ蓄電池用の非焼結式ニッケル電極、すなわち正極３について説明する。 The negative electrode 4 is prepared by adjusting a negative electrode slurry composed of a hydrogen storage alloy powder, a binder, water, and a conductive agent blended as necessary, and rolling the negative electrode substrate coated with the negative electrode slurry after drying. -It can be cut and made.
Hereinafter, a non-sintered nickel electrode for an alkaline storage battery according to an embodiment of the present invention, that is, the positive electrode 3 will be described.

非焼結式ニッケル電極は、導電性の正極基板と、正極基板に保持された正極合剤とからなる。正極基板としては、例えば、ニッケルめっきが施された網状、スポンジ状、繊維状、フエルト状の金属多孔体を用いることができる。
正極合剤は、図１の円内に概略的に示したように、正極活物質粒子14、導電剤粒子15及び結着剤16からなり、正極活物質粒子14及び導電剤粒子15は、結着剤16によって正極基板の骨格17に固定されている。 The non-sintered nickel electrode is composed of a conductive positive electrode substrate and a positive electrode mixture held on the positive electrode substrate. As the positive electrode substrate, for example, a net-like, sponge-like, fiber-like, or felt-like metal porous body plated with nickel can be used.
As schematically shown in the circle of FIG. 1, the positive electrode mixture is composed of positive electrode active material particles 14, conductive agent particles 15 and binder 16, and the positive electrode active material particles 14 and conductive agent particles 15 are bonded together. It is fixed to the skeleton 17 of the positive electrode substrate by an adhesive 16.

結着剤16としては、例えば、カルボキシメチルセルロース、メチルセルロース、PTFEディスパージョン、HPCディスパージョンなどを用いることができる。
正極活物質粒子14は、例えば、略球状をなし、5μm以上20μm以下の範囲の平均粒径を有する。平均粒径は、レーザ回折・散乱法により求めた粒径の分布において重量積分50%にあたる粒径である。 As the binder 16, for example, carboxymethylcellulose, methylcellulose, PTFE dispersion, HPC dispersion and the like can be used.
The positive electrode active material particles 14 are, for example, substantially spherical and have an average particle size in the range of 5 μm to 20 μm. The average particle size is a particle size corresponding to 50% by weight in the particle size distribution obtained by the laser diffraction / scattering method.

正極活物質粒子14は必須の主成分として水酸化ニッケル系化合物を含む。水酸化ニッケル系化合物としては、水酸化ニッケル、ニッケルの平均価数が2価よりも大の水酸化ニッケル（高次水酸化ニッケル）、又は水酸化ニッケルと高次水酸化ニッケルの混合物を用いることができる。また、正極活物質粒子14は、任意の添加成分として、例えば亜鉛やコバルトを含んでいてもよく、水酸化ニッケル系化合物と、亜鉛やコバルトとは、固溶体を形成していてもよい。   The positive electrode active material particles 14 contain a nickel hydroxide compound as an essential main component. As nickel hydroxide compounds, use nickel hydroxide, nickel hydroxide whose nickel average valence is higher than divalent (higher order nickel hydroxide), or a mixture of nickel hydroxide and higher order nickel hydroxide. Can do. In addition, the positive electrode active material particles 14 may contain, for example, zinc or cobalt as an optional additive component, and the nickel hydroxide compound and zinc or cobalt may form a solid solution.

正極活物質粒子14の表面の少なくとも一部若しくは全部は、好ましくは、被覆層18で覆われ、被覆層18は、コバルト化合物を主成分としている。そして、コバルト化合物は、乱れた結晶構造を有し且つコバルトの平均価数が２価以上であるのが好ましい。
このような乱れた結晶構造を有し且つ平均価数が２価以上のコバルトを含むコバルト化合物の被覆層18を有する正極活物質粒子14は、水酸化ニッケル粉末とコバルト化合物粉末を、酸素を含む雰囲気下で加熱すると同時にアルカリ水溶液を添加しながら混合した後、乾燥させて得ることができる。 At least a part or all of the surface of the positive electrode active material particles 14 is preferably covered with a coating layer 18, and the coating layer 18 is mainly composed of a cobalt compound. The cobalt compound preferably has a disordered crystal structure and the average valence of cobalt is 2 or more.
The positive electrode active material particle 14 having such a disordered crystal structure and having a cobalt compound coating layer 18 containing cobalt having an average valence of 2 or more contains nickel hydroxide powder and cobalt compound powder, and contains oxygen. It can be obtained by heating in an atmosphere and mixing while adding an alkaline aqueous solution and then drying.

導電剤粒子15は、例えば、非球状をなし、1μm以上5μm以下の範囲の平均粒径（平均球相当径）を有する。平均球相当径は、レーザ回折・散乱法により求めた球相当径の分布において重量積分50%にあたる球相当径である。
導電剤粒子15は複合酸化物からなり、複合酸化物の組成は、一般式（１）：
LiNiｘCoｙMnｚO２
で示される。ただし式中、ｘ，ｙ及びｚは、0＜x＜1，0＜y＜1，0＜z＜1，x+y+z=1で示される関係を満たす。ｘ，ｙ，zの好ましい範囲は、0.2＜x＜0.4，0.2＜y＜0.4，0.2＜z＜0.4である。 The conductive agent particles 15 are, for example, non-spherical and have an average particle diameter (average sphere equivalent diameter) in the range of 1 μm to 5 μm. The average equivalent sphere diameter is the equivalent sphere diameter corresponding to 50% by weight integral in the distribution of equivalent sphere diameters obtained by the laser diffraction / scattering method.
The conductive agent particles 15 are composed of a complex oxide, and the composition of the complex oxide is represented by the general formula (1):
LiNi x Co y Mn z O 2
Indicated by However, in the formula, x, y, and z satisfy the relationship represented by 0 <x <1, 0 <y <1, 0 <z <1, x + y + z = 1. Preferred ranges of x, y, and z are 0.2 <x <0.4, 0.2 <y <0.4, and 0.2 <z <0.4.

導電剤粒子15は、例えば、以下のようにして作製することができる。
まず、原材料として、水酸化ニッケル等のニッケル酸化物と、酸化コバルト等のコバルト酸化物と、酸化マンガン等のマンガン酸化物と、炭酸リチウムとを一般式（１）で示される組成になるよう秤量してから混合する。得られた混合物を、所定の温度及び時間焼成し、得られた焼成物を機械的に粉砕してから篩い分ける。これにより所望の組成及び粒径（球相当径）を有する導電剤粒子15が作製される。 The conductive agent particles 15 can be produced, for example, as follows.
First, as raw materials, nickel oxide such as nickel hydroxide, cobalt oxide such as cobalt oxide, manganese oxide such as manganese oxide, and lithium carbonate are weighed so as to have a composition represented by the general formula (1). Then mix. The obtained mixture is fired at a predetermined temperature and time, and the obtained fired product is mechanically pulverized and sieved. As a result, conductive agent particles 15 having a desired composition and particle diameter (sphere equivalent diameter) are produced.

そして、上記した非焼結式ニッケル電極は、例えば、正極活物質粒子14、導電剤粒子15、結着剤16、及び水を混練して正極用スラリを調製し、この正極用スラリが塗着・充填されたスラリ付きの正極基板を、スラリの乾燥を経てから圧延・裁断して作製することができる。
なお、正極用スラリを調製する際、正極活物質粒子14に含まれる100質量部の水酸化ニッケル系化合物に対し、１質量部以上10質量部以下の範囲の導電剤粒子15を添加するのが好ましい。つまり、正極合剤中、100質量部の水酸化ニッケル化合物に対し、１質量部以上10質量部以下の範囲の複合酸化物が含まれているのが好ましい。 The non-sintered nickel electrode described above is prepared by, for example, kneading the positive electrode active material particles 14, the conductive agent particles 15, the binder 16, and water to prepare a positive electrode slurry, and the positive electrode slurry is applied to the non-sintered nickel electrode. A filled positive electrode substrate with a slurry can be produced by rolling and cutting after drying the slurry.
When preparing the slurry for the positive electrode, the conductive agent particles 15 in the range of 1 part by mass or more and 10 parts by mass or less are added to 100 parts by mass of the nickel hydroxide compound contained in the positive electrode active material particles 14. preferable. That is, the positive electrode mixture preferably contains a composite oxide in the range of 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the nickel hydroxide compound.

上述したアルカリ蓄電池用の非焼結式正極は、導電剤粒子（複合酸化物粒子）15を含み、導電剤粒子15を構成する複合酸化物の組成は、一般式（１）で示される。この複合酸化物は、従来の複合酸化物、コバルト複合化合物又はリチオ酸化物に比べて耐還元性に優れている。
このため、上述したニッケル水素二次電池を過放電状態や高温下で放置したとき、導電性マトリックスとしての複合酸化物中のコバルトの還元が抑制され、放置後の電池容量の低下が大幅に抑制される。つまり、この電池にあっては、過放電状態や高温下での放置後にも、導電性マトリックスが良好な導電性を有しているため活物質の利用率が高く、容量低下が少ない。 The non-sintered positive electrode for an alkaline storage battery described above includes conductive agent particles (composite oxide particles) 15 and the composition of the composite oxide constituting the conductive agent particles 15 is represented by the general formula (1). This composite oxide is excellent in reduction resistance as compared with conventional composite oxides, cobalt composite compounds, or lithio oxides.
For this reason, when the nickel hydride secondary battery described above is left in an overdischarged state or at a high temperature, the reduction of cobalt in the composite oxide as the conductive matrix is suppressed, and the decrease in battery capacity after being left is greatly suppressed. Is done. That is, in this battery, even after being left in an overdischarged state or at a high temperature, since the conductive matrix has good conductivity, the utilization rate of the active material is high, and the capacity reduction is small.

また、上述した非焼結式正極では、100質量部の水酸化ニッケル系化合物に対し、１質量部以上10質量部以下の範囲の複合酸化物を含むことで、導電剤粒子15が導電性に優れた導電性マトリックスを形成しながら、活物質量が十分に確保される。
更に、上述した非焼結式正極では、活物質粒子の少なくとも一部がコバルト化合物の被覆層18で覆われることにより、導電性においてより優れた導電性マトリックスが形成される。 In the non-sintered positive electrode described above, the conductive agent particles 15 are made conductive by including a composite oxide in the range of 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the nickel hydroxide compound. A sufficient amount of active material is ensured while forming an excellent conductive matrix.
Further, in the above-described non-sintered positive electrode, at least a part of the active material particles is covered with the coating layer 18 of the cobalt compound, thereby forming a conductive matrix having better conductivity.

本発明は上記した一実施形態に限定されることはなく、種々変形が可能であり、電池は、角形電池であってもよく、電池の機械的な構造は格別限定されることはない。
また、一実施形態では、負極板24が水素吸蔵合金電極であったが、カドミウム電極であってもよい。
更に、本発明のアルカリ蓄電池用の非焼結式電極は、過放電状態又は高温下で放置したときに容量低下を招かない範囲で、他の化合物を含んでいてもよい。 The present invention is not limited to the above-described embodiment, and various modifications are possible. The battery may be a square battery, and the mechanical structure of the battery is not particularly limited.
In one embodiment, the negative electrode plate 24 is a hydrogen storage alloy electrode, but may be a cadmium electrode.
Furthermore, the non-sintered electrode for an alkaline storage battery of the present invention may contain other compounds as long as the capacity is not reduced when left in an overdischarged state or at a high temperature.

１．導電剤粒子、正極及び電池の作製
（１）実施例１
（ｉ）導電剤粒子の作製
水酸化ニッケルと、酸化コバルトと、酸化マンガンと、炭酸リチウムとを表１に示された組成になるよう秤量してから混合した。得られた混合物を、所定の温度及び時間焼成してから、焼成物を機械的に粉砕した。そして、粉砕物を篩い分けて、平均粒径が3μmの導電剤粒子を作製した。 1. Production of Conductive Agent Particles, Positive Electrode and Battery (1) Example 1
(I) Production of Conductive Agent Particles Nickel hydroxide, cobalt oxide, manganese oxide, and lithium carbonate were weighed to have the composition shown in Table 1 and mixed. The obtained mixture was fired at a predetermined temperature and time, and then the fired product was mechanically pulverized. Then, the pulverized product was sieved to produce conductive agent particles having an average particle size of 3 μm.

（ii）非焼結式正極の作製
得られた導電剤粒子と、水酸化ニッケル粒子の表面に、結晶構造が乱され且つコバルトの平均価数が２価以上のコバルト化合物の被覆層が形成された正極活物質粒子と、結着剤としてのPTFEディスパージョンとを、正極活物質粒子中の水酸化ニッケル100質量部に対し導電剤粒子5質量部、PTFEディスパージョン1質量部の割合にて混合し、正極用スラリを調製した。正極基板としてのニッケル多孔体（多孔度95、平均孔径300μm）に、得られた正極スラリを所定の充填量にて充填したものを、正極スラリの乾燥後、所定厚みに圧延してから所定寸法に切断し、非焼結式正極を作製した。 (Ii) Production of non-sintered positive electrode A coating layer of a cobalt compound having a disordered crystal structure and an average cobalt valence of 2 or more is formed on the surface of the obtained conductive agent particles and nickel hydroxide particles. The positive electrode active material particles and PTFE dispersion as a binder were mixed at a ratio of 5 parts by mass of conductive agent particles and 1 part by mass of PTFE dispersion with respect to 100 parts by mass of nickel hydroxide in the positive electrode active material particles. Thus, a positive electrode slurry was prepared. A nickel porous body (porosity 95, average pore diameter 300 μm) as a positive electrode substrate filled with the obtained positive electrode slurry with a predetermined filling amount, dried to a predetermined thickness after drying the positive electrode slurry, and then with predetermined dimensions A non-sintered positive electrode was produced.

（iii）ニッケル水素二次電池の組立て
得られた非焼結式正極と、非焼結式正極の1.5倍の容量を有する水素吸蔵合金電極とを、ポリアミド系不織布からなるセパレータを介して渦巻状に巻回し、電極群を作製した。得られた電極群を外装缶内に収納して所定の取付工程を行った後、外装缶内に水酸化カリウム水溶液を主成分とする8Nのアルカリ電解液を注液した。そして、外装缶の開口を蓋板等を用いて封口し、公称容量が1200mAhでAAサイズの密閉円筒形ニッケル水素二次電池を組み立てた。
（２）比較例1〜5
実施例１の導電剤粒子（複合酸化物）に代えて、表１に示した組成を有する化合物の粒子を用いた以外は実施例１の場合と同様にして非焼結式正極を作製し、そして、ニッケル水素二次電池を作製した。 (Iii) Assembling the nickel-metal hydride secondary battery The obtained non-sintered positive electrode and a hydrogen storage alloy electrode having a capacity 1.5 times that of the non-sintered positive electrode are spirally connected via a separator made of polyamide nonwoven fabric. The electrode group was produced. The obtained electrode group was housed in an outer can and subjected to a predetermined attachment process, and then an 8N alkaline electrolyte mainly composed of an aqueous potassium hydroxide solution was injected into the outer can. Then, the opening of the outer can was sealed with a cover plate or the like, and an AA-sized sealed cylindrical nickel-metal hydride secondary battery with a nominal capacity of 1200 mAh was assembled.
(2) Comparative Examples 1-5
A non-sintered positive electrode was produced in the same manner as in Example 1 except that the compound particles having the composition shown in Table 1 were used instead of the conductive agent particles (composite oxide) of Example 1. And the nickel hydride secondary battery was produced.

なお、比較例4及び5では、導電剤粒子として、LiCoO2とNiO又はMnOとの混合物を用いた。各導電剤粒子は、100質量部のLiCoO2粒子に対し、10質量部のNiO粒子又は10質量部のMnO粒子を含む。
２．電池の特性評価
得られた各ニッケル水素二次電池について以下の評価を行った。
（１）充放電試験
各電池に、25℃の室温下において、120mAh（0.1It）の充電電流で16時間の充電を行った後、1200mAh（1It）の放電電流で放電終止電圧が1.0Vになるまで放電させ、このときの放電容量を測定した。これらの結果を、比較例２の値を100とした相対値にて表１に示す。 In Comparative Examples 4 and 5, a mixture of LiCoO 2 and NiO or MnO was used as the conductive agent particles. Each conductive agent particle includes 10 parts by mass of NiO particles or 10 parts by mass of MnO particles with respect to 100 parts by mass of LiCoO 2 particles.
2. Battery characteristic evaluation The following evaluation was performed about each obtained nickel-hydrogen secondary battery.
(1) Charge / Discharge Test After charging each battery for 16 hours at a room temperature of 25 ° C with 120mAh (0.1It) charge current, the end-of-discharge voltage is 1.0V with 1200mAh (1It) discharge current. It discharged until it became, and the discharge capacity at this time was measured. These results are shown in Table 1 as relative values with the value of Comparative Example 2 as 100.

（２）過放電試験（容量回復率試験）
各電池に、25℃の室温下において、1200mAh（1It）の充電電流で1.2時間の充電を行った後、1200mAh（1It）の放電電流で放電終止電圧が1.0Vになるまで放電させる充放電サイクルを５回繰り返し行い、５回目の放電容量を測定した。この測定後、各電池を、正負極間が１Ωの抵抗体を介して短絡された状態で、温度60℃の雰囲気下に２週間放置してから、放置された電池に再び前述の充放電サイクルを５回繰り返し行い、５回目の放電容量を測定した。そして、放置後の放電容量を放置前の放電容量で除した値を、短絡保存後の容量回復率として表１に示した。 (2) Overdischarge test (capacity recovery rate test)
A charge / discharge cycle in which each battery is charged at 1200 mAh (1 It) at a charge current of 1200 mAh (1 It) at room temperature of 25 ° C. for 1.2 hours and then discharged at a discharge current of 1200 mAh (1 It) until the discharge end voltage reaches 1.0 V. Was repeated five times, and the discharge capacity at the fifth time was measured. After this measurement, each battery is left in an atmosphere at a temperature of 60 ° C. for 2 weeks with the positive and negative electrodes short-circuited through a 1Ω resistor, and then the above charge / discharge cycle is applied again to the left battery. Was repeated five times, and the discharge capacity at the fifth time was measured. The value obtained by dividing the discharge capacity after being left by the discharge capacity before being left is shown in Table 1 as the capacity recovery rate after short-circuit storage.

Figure 2008084736
Figure 2008084736

表１から次のことが明らかである。
（１）実施例１及び比較例1〜5の間で、放電容量は略同じである。これより、実施例１の複合酸化物（三成分系）は、Mnを含むことで比較例１の酸化物、比較例２の複合酸化物（一成分系）、比較例３の複合酸化物（二成分系）及び比較例4〜5の複合酸化物とNi酸化物やマンガン酸化物との混合物よりもCoの比率が小さいにもかかわらず、比較例1〜5の酸化物と略同じ導電性を有することがわかる。
（２）実施例１の電池は、比較例1〜5の電池に比べて、容量回復率が高い。これより、実施例１の複合酸化物は、比較例1〜5の酸化物に比べて、耐還元性に優れていることがわかる。 From Table 1, the following is clear.
(1) The discharge capacity is substantially the same between Example 1 and Comparative Examples 1-5. Thus, the composite oxide of Example 1 (three-component system) contains Mn, so that the oxide of Comparative Example 1, the composite oxide of Comparative Example 2 (one-component system), and the composite oxide of Comparative Example 3 ( Two-component system) and substantially the same conductivity as the oxides of Comparative Examples 1 to 5 even though the ratio of Co is smaller than the mixture of the composite oxides of Comparative Examples 4 to 5 and Ni oxides or manganese oxides It can be seen that
(2) The battery of Example 1 has a higher capacity recovery rate than the batteries of Comparative Examples 1-5. From this, it can be seen that the composite oxide of Example 1 is excellent in reduction resistance as compared with the oxides of Comparative Examples 1 to 5.

本発明の一実施形態に係るアルカリ蓄電池用の非焼結式正極が適用されたニッケル水素二次電池を示す部分切欠斜視図であり、図中円内は正極板の一部を拡大して概略的に示した断面図である。1 is a partially cutaway perspective view showing a nickel metal hydride secondary battery to which a non-sintered positive electrode for an alkaline storage battery according to an embodiment of the present invention is applied. FIG.

符号の説明Explanation of symbols

１ 外装缶
２ 電極群
３ 正極（非焼結式正極）
４ 負極（水素吸蔵合金電極）
５ セパレータ
14 正極活物質粒子（活物質粒子）
15 導電剤粒子（複合酸化物粒子） 1 exterior can 2 electrode group 3 positive electrode (non-sintered positive electrode)
4 Negative electrode (hydrogen storage alloy electrode)
5 Separator
14 Positive electrode active material particles (active material particles)
15 Conductive agent particles (composite oxide particles)

Claims (3)

水酸化ニッケル系化合物を主成分とする活物質粒子と、
一般式：LiNiｘCoｙMnｚO２
（ただし式中、ｘ，ｙ及びｚは、0＜x＜1，0＜y＜1，0＜z＜1，x+y+z=1で示される関係を満たす）
で示される組成を有する複合酸化物粒子と
を含むことを特徴とするアルカリ蓄電池用の非焼結式正極。 Active material particles mainly composed of nickel hydroxide compounds,
General formula: LiNi x Co y Mn z O 2
(Where x, y and z satisfy the relationship represented by 0 <x <1, 0 <y <1, 0 <z <1, x + y + z = 1)
A non-sintered positive electrode for an alkaline storage battery, comprising composite oxide particles having a composition represented by: 前記活物質粒子に含まれる前記水酸化ニッケル系化合物100質量部に対し、１質量部以上10質量部以下の範囲の前記複合酸化物粒子を含むことを特徴とする請求項１に記載のアルカリ蓄電池用の非焼結式正極。   2. The alkaline storage battery according to claim 1, comprising the composite oxide particles in a range of 1 part by mass to 10 parts by mass with respect to 100 parts by mass of the nickel hydroxide-based compound contained in the active material particles. Non-sintered positive electrode for use. 前記活物質粒子の少なくとも一部を覆う被覆層を更に含み、
前記被覆層は、コバルト化合物を主成分として含む
ことを特徴とする請求項１に記載のアルカリ蓄電池用の非焼結式正極。 A coating layer covering at least a part of the active material particles;
The said coating layer contains a cobalt compound as a main component, The non-sintered positive electrode for alkaline storage batteries of Claim 1 characterized by the above-mentioned.
JP2006264608A 2006-09-28 2006-09-28 Non-sintered positive electrode for alkaline storage battery Pending JP2008084736A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10326616A (en) * 1997-05-28 1998-12-08 Matsushita Electric Ind Co Ltd Alkaline storage battery
JPH11149921A (en) * 1997-03-21 1999-06-02 Matsushita Electric Ind Co Ltd Alkali storage battery and surface treatment method of its positive electrode substance

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11149921A (en) * 1997-03-21 1999-06-02 Matsushita Electric Ind Co Ltd Alkali storage battery and surface treatment method of its positive electrode substance
JPH10326616A (en) * 1997-05-28 1998-12-08 Matsushita Electric Ind Co Ltd Alkaline storage battery

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