JP2000149938A - Nickel positive electrode active material - Google Patents
Nickel positive electrode active materialInfo
- Publication number
- JP2000149938A JP2000149938A JP10313013A JP31301398A JP2000149938A JP 2000149938 A JP2000149938 A JP 2000149938A JP 10313013 A JP10313013 A JP 10313013A JP 31301398 A JP31301398 A JP 31301398A JP 2000149938 A JP2000149938 A JP 2000149938A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- active material
- nickel
- nickel hydroxide
- surface area
- 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.)
- Granted
Links
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
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ニッケル正極活物
質に関し、更に詳しくは、ニッケル水素蓄電池或いはニ
ッケルカドミウム（ニカド）蓄電池等の各種ニッケル系
蓄電池用の正極材料として好適なニッケル正極活物質に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel positive electrode active material, and more particularly to a nickel positive electrode active material suitable as a positive electrode material for various nickel-based batteries such as nickel-metal hydride batteries or nickel cadmium (NiCd) batteries. It is.
【０００２】[0002]
【従来の技術】近年、ニッケル水素蓄電池やニカド電池
等のニッケル系蓄電池が、その特性として、放電曲線
が平坦で、安定した電池出力が放電末期まで得られる、
充放電のサイクル寿命が長い、急速充電や過放電に
強い、安全で使いやすい等の利点を有することで注目
されており、携帯電話やコードレス情報機器（ノートパ
ソコン）、自動車電源等の用途への適用が期待されてい
る。2. Description of the Related Art In recent years, nickel-based storage batteries such as nickel-metal hydride storage batteries and nickel-cadmium batteries have a characteristic that a discharge curve is flat and a stable battery output can be obtained until the end of discharge.
It has attracted attention because of its advantages such as long charge / discharge cycle life, strong resistance to rapid charging and overdischarge, and safety and ease of use. It is used for applications such as mobile phones, cordless information devices (notebook PCs), and automobile power supplies. Application is expected.
【０００３】その中で例えば、ニッケル水素蓄電池は、
次の化１にその充放電の全電池反応を示したが、充電時
には正極で水酸化ニッケル（Ｎｉ（ＯＨ）２）が電解液
とのプロトン交換により水素を手放してオキシ水酸化ニ
ッケル（ＮｉＯＯＨ）となり、逆に放電時には、電解液
中の水素を取り込み水酸化ニッケルに戻るという挙動を
示す。一方負極では、水素吸蔵合金（Ｍ）が、充電時に
は電解液中の水素を吸蔵し水素化物（ＭＨ）となり、ま
た、放電時にはその水素を電解液中に放出するという反
応を繰り返す。[0003] Among them, for example, a nickel-metal hydride battery is
The whole battery reaction of charge and discharge is shown in the following chemical formula 1. At the time of charging, nickel hydroxide (Ni (OH) 2 ) at the positive electrode releases hydrogen by proton exchange with the electrolytic solution, and nickel oxyhydroxide (NiOOH) On the contrary, at the time of discharge, the behavior of taking in hydrogen in the electrolytic solution and returning to nickel hydroxide is exhibited. On the other hand, in the negative electrode, the hydrogen storage alloy (M) repeats a reaction of absorbing hydrogen in the electrolytic solution to form a hydride (MH) during charging and releasing the hydrogen into the electrolytic solution during discharging.
【０００４】[0004]
【化１】 Embedded image
【０００５】ところで、このニッケル水素蓄電池の正極
には従来２つのタイプが知られており、その１つは「焼
結式正極」、他の１つは「ペースト式正極」と称される
ものである。そして、前者の「焼結式正極」は、ニッケ
ルメッキした穿孔鋼板の表面にＮｉ微粒子からなるペー
ストを塗布し、乾燥後、８００℃程度の水素雰囲気下で
焼成して集電体を作製し、この集電体を硝酸ニッケル溶
液に含浸し、電解若しくは水酸化ナトリウム溶液にて中
和して水酸化ニッケル層を集電体上に形成することによ
り製作される。この「焼結式正極」によれば、集電体上
に均一に水酸化ニッケル層が形成されているため高出力
が得られるが、その反面、水酸化ニッケルの充填量が制
限されるために単位体積当たりの容量が小さいという欠
点がある。[0005] By the way, two types of positive electrodes of this nickel-metal hydride storage battery are conventionally known, one of which is called a "sintered positive electrode" and the other is called a "paste positive electrode". is there. The former “sintered positive electrode” is obtained by applying a paste made of Ni fine particles to the surface of a nickel-plated perforated steel sheet, drying it, and firing it in a hydrogen atmosphere at about 800 ° C. to produce a current collector. The current collector is manufactured by impregnating the same with a nickel nitrate solution, and electrolyzing or neutralizing with a sodium hydroxide solution to form a nickel hydroxide layer on the current collector. According to the “sintered positive electrode”, a high output is obtained because the nickel hydroxide layer is uniformly formed on the current collector, but on the other hand, the filling amount of the nickel hydroxide is limited. There is a disadvantage that the capacity per unit volume is small.
【０００６】一方、後者の「ペースト式正極」は、緻密
で平均粒子径が１０〜１５μｍの水酸化ニッケル粒子
（正極活物質）からなる活物質ペーストを発泡Ｎｉ集電
体に充填し、乾燥後、加圧成形することにより製作され
る。この「ペースト式正極」によれば、水酸化ニッケル
の充填量を増やせるので単位体積当たりの容量が大き
く、「焼結式正極」よりも高容量化が期待されるもので
ある。On the other hand, the latter “paste-type positive electrode” is a method in which an active material paste composed of nickel hydroxide particles (positive electrode active material) having a dense and average particle diameter of 10 to 15 μm is filled in a foamed Ni current collector and dried. It is manufactured by press molding. According to the "paste-type positive electrode", the capacity per unit volume is large since the filling amount of nickel hydroxide can be increased, and a higher capacity than the "sintered-type positive electrode" is expected.
【０００７】そこで、この「ペースト式正極」に用いら
れる正極活物質である「水酸化ニッケル粒子」の製造法
として従来一般に知られているものの１つが、いわゆる
粉砕タイプの水酸化ニッケルを製造する方法であって、
例えば特開平２−６３４０号公報等に示されるように、
硝酸ニッケル、硫酸ニッケル等のニッケル塩水溶液と、
水酸化ナトリウム等のアルカリ金属水酸化物との中和反
応により水酸化ニッケルの沈殿物を生成し、その水酸化
ニッケルの沈殿物を乾燥・粉砕することにより得られる
ものである。Therefore, one of the generally known methods for producing "nickel hydroxide particles" as a positive electrode active material used in the "paste type positive electrode" is a method for producing a so-called pulverized type nickel hydroxide. And
For example, as shown in JP-A-2-6340,
Nickel salt aqueous solution such as nickel nitrate and nickel sulfate;
It is obtained by forming a precipitate of nickel hydroxide by a neutralization reaction with an alkali metal hydroxide such as sodium hydroxide and drying and pulverizing the precipitate of nickel hydroxide.
【０００８】また、別の製法として、例えば特開平１０
−７４５１４号公報に示されるように、アンモニウム水
溶液や硫酸アンモニウム水溶液のようなアンモニウムイ
オンを含むアルカリ水溶液を攪拌しながら、その溶液に
硝酸ニッケル、硫酸ニッケル等のニッケル塩溶液を滴下
（このときにｐＨ調整剤として水酸化ナトリウム水溶液
も同時に滴下する。）し、水酸化ニッケルの結晶粒子を
析出により得るというものも知られている。Further, as another manufacturing method, for example,
As described in JP-A-74514, a nickel salt solution such as nickel nitrate or nickel sulfate is added dropwise to an alkaline aqueous solution containing ammonium ions such as an aqueous ammonium solution or an aqueous ammonium sulfate solution while stirring the solution (at this time, the pH is adjusted). An aqueous solution of sodium hydroxide is also dropped simultaneously as an agent) to obtain crystal particles of nickel hydroxide by precipitation.
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、上述し
た従来の粉砕タイプの水酸化ニッケルを正極活物質とし
て用いた場合には、その粉砕された水酸化ニッケルの表
面形状が角ばっていることによるものと思われるが、発
泡Ｎｉ集電体への充填密度がそれ程高くはならず、正極
の高容量化並びに高出力化が十分には得られないという
問題があった。However, when the above-mentioned conventional pulverized type nickel hydroxide is used as a positive electrode active material, the surface shape of the pulverized nickel hydroxide is square. However, there is a problem that the filling density of the foamed Ni current collector does not become so high, and the capacity and output of the positive electrode cannot be sufficiently increased.
【００１０】また、後者の水酸化ニッケルの結晶粒子を
正極活物質として用いた場合には、その水酸化ニッケル
の結晶粒子が比較的球状に近いために発泡Ｎｉ集電体へ
の充填密度が上がり、正極の高容量化が図れるものの、
その一方で水酸化ニッケルの結晶粒子の表面には、走査
型電子顕微鏡（ＳＥＭ）により観察すると良く分かる
が、幅０．０２μｍ、長さ０．５μｍ程度の片状結晶が
存在しており、放電時にこの片状結晶部分を介して水素
拡散が行われていることから高い電池出力を得られなか
った。When the latter nickel hydroxide crystal particles are used as the positive electrode active material, the packing density of the foamed Ni current collector increases because the nickel hydroxide crystal particles are relatively nearly spherical. , While increasing the capacity of the positive electrode,
On the other hand, the surface of the nickel hydroxide crystal particles can be clearly understood by observation with a scanning electron microscope (SEM), and flake crystals having a width of about 0.02 μm and a length of about 0.5 μm are present. At times, high battery output could not be obtained because hydrogen was diffused through the flaky crystal portion.
【００１１】この片状結晶の水酸化ニッケルについて、
もう少し詳しく説明すると、図４は、この水酸化ニッケ
ルの結晶粒子の表面形態を模式的に示したものであり、
点線で示した部分が活物質のバルク表面で、実線で示し
た部分がそのバルク表面に形成される片状結晶を示して
いる。また図５は、この正極活物質の充電反応が起きる
片状結晶表面（Ａ点）とバルク表面（Ｂ点）と活物質内
部（Ｃ点）との水素拡散濃度の変化を図示したものであ
る。Regarding the nickel hydroxide of the flaky crystal,
More specifically, FIG. 4 schematically shows the surface morphology of the nickel hydroxide crystal particles.
The portion shown by the dotted line is the bulk surface of the active material, and the portion shown by the solid line is the flake crystals formed on the bulk surface. FIG. 5 illustrates the change in the hydrogen diffusion concentration on the flaky crystal surface (point A), the bulk surface (point B), and the inside of the active material (point C) where the charging reaction of the positive electrode active material occurs. .
【００１２】水酸化ニッケル中の水素の拡散定数は、１
０−１１〜１０−１０ｃｍ２ｓ−１と報告されており、
水素拡散がどの程度の深さまで及んでいるかを示す値
（ｄ＝（２πＤｔ）１／２）を取りあえずｔ＝１０秒と
して計算すると０．２５〜０．７９μｍとなる。ｄは、
水素拡散層の深さと呼ばれる。図５に示すような片状結
晶を有する水酸化ニッケルの結晶粒子によれば、結晶粒
子表面の水素拡散層の厚さがバルク表面の片状結晶の突
出サイズ（長さ０．５μｍ程度）を超えると、点線で示
したバルク表面（Ｂ点）での水素（Ｈ）移動量によって
正極の出力や表面電位が決定されることになる。The diffusion constant of hydrogen in nickel hydroxide is 1
0 -11 to 10 -10 cm 2 s -1 ,
When a value (d = (2πDt) 1/2 ) indicating the depth to which hydrogen diffusion extends is calculated for the time being t = 10 seconds, it becomes 0.25 to 0.79 μm. d is
It is called the depth of the hydrogen diffusion layer. According to the nickel hydroxide crystal particles having the flaky crystal as shown in FIG. 5, the thickness of the hydrogen diffusion layer on the surface of the crystal particle is smaller than the protrusion size (length about 0.5 μm) of the flaky crystal on the bulk surface. If it exceeds, the output and surface potential of the positive electrode are determined by the amount of hydrogen (H) transfer on the bulk surface (point B) indicated by the dotted line.
【００１３】そこで、その水素（Ｈ）移動量は、バルク
表面の表面積と片状結晶を介して水素（Ｈ）濃度勾配と
により次の数１で表示され、バルク表面の表面積は結晶
粒子の粒子径に反比例するために結晶粒子径が大きいと
バルク表面の表面積が小さくなり、一方、片状結晶を介
してのＨ濃度勾配（Ａ点→Ｂ点→Ｃ点）は大きくなるた
めにバルク表面の水素（Ｈ）濃度が変化して、正極電位
の変化が大きくなり、正極抵抗が増大することにより出
力が低下するという問題があった。Therefore, the amount of hydrogen (H) transfer is expressed by the following equation 1 by the surface area of the bulk surface and the hydrogen (H) concentration gradient through the flake crystal. When the crystal particle diameter is large because the diameter is inversely proportional to the diameter, the surface area of the bulk surface becomes small. On the other hand, the H concentration gradient (point A → point B → point C) through the flaky crystal becomes large. There has been a problem that the hydrogen (H) concentration changes, the change in the positive electrode potential increases, and the output decreases due to an increase in the positive electrode resistance.
【００１４】[0014]
【数１】 （Ｈ移動量）∝（バルク表面積）×（Ｈ濃度勾配）(H transfer amount) １ (Bulk surface area) × (H concentration gradient)
【００１５】また、バルク表面積のＨ濃度勾配が大きく
変化して正極抵抗が大きくなると、充放電の繰り返しに
より温度上昇（６０℃）したときに正極の充電電位と水
の電解電位が接近し、片状結晶面でのＨ濃度が低くなる
ことにより正極電位が貴にシフトして、水の電解（水素
発生）が副反応として生じ、充電受入性が低下するとい
う問題があった。When the positive electrode resistance increases due to a large change in the H concentration gradient of the bulk surface area, the charge potential of the positive electrode and the electrolytic potential of water approach each other when the temperature rises (60 ° C.) due to repetition of charge and discharge. When the H concentration on the crystal face becomes low, the potential of the positive electrode shifts preciously, and water electrolysis (hydrogen generation) occurs as a side reaction, and the charge acceptability decreases.
【００１６】更に、ニッケル水素蓄電池の正極には、水
酸化ニッケル以外にも水酸化コバルトや金属コバルト等
が配合され、これらの配合成分は充電によって３価のオ
キシ水酸化コバルトとなって放電リザーブを形成し、ま
た、導電性の高いオキシ水酸化コバルトは、水酸化ニッ
ケルや芯材表面に均一に分散して導電性ネットワークを
形成し、集電性能を高めて活物質の利用率を確保する役
目を果たすことが知られているが、片状の水酸化ニッケ
ルによって表面積が大きくなっているため、導電性を付
与するため活物質表面に形成されるオキシ水酸化コバル
ト層が薄くなる。そのため、高出力化しようとして片状
結晶を多数有する小粒子径の活物質粒子を用いようとす
ると、従来の２倍量（２０ｍａｓｓ％）の酸化コバルト
（ＣｏＯ）を添加しなければならず、材料コストが高く
なるという問題もあった。Further, in addition to nickel hydroxide, cobalt hydroxide, metal cobalt, and the like are blended in the positive electrode of the nickel-metal hydride storage battery, and these blended components become trivalent cobalt oxyhydroxide upon charging to discharge reserve. Formed and highly conductive cobalt oxyhydroxide is uniformly dispersed on the surface of nickel hydroxide and the core material to form a conductive network, which enhances current collection performance and ensures the active material utilization rate. However, since the surface area is increased by the flaky nickel hydroxide, the cobalt oxyhydroxide layer formed on the surface of the active material for imparting conductivity becomes thin. Therefore, in order to increase the output and use active material particles having a small particle diameter having a large number of flake crystals, it is necessary to add twice (20 mass%) of cobalt oxide (CoO) as compared with a conventional material. There was also a problem that the cost was high.
【００１７】そこで、本発明者らは、種々の実験を重ね
た結果、活物質粒子において水素移動量を確保するため
には活物質粒子の粒子径（μｍ）と表面積（ｍ２／ｇ）
との関係を律すれば良いとの考えに至った。活物質粒子
の粒子径を小さくすることでトータルとしてのバルク表
面積を大きくしてバルク表面の水素移動量を確保し、ま
た、バルク表面の片状結晶の生成を抑制して結晶粒子の
比表面積も小さくすることでバルク表面の水素濃度勾配
を小さくすることにより正極抵抗を減少させることがで
きるとの考えるに至ったものである。The present inventors have conducted various experiments and found that the particle diameter (μm) and the surface area (m 2 / g) of the active material particles were assured in order to secure the hydrogen transfer amount in the active material particles.
I came to the idea that I should govern my relationship. By reducing the particle size of the active material particles, the total surface area of the bulk is increased to secure the amount of hydrogen transfer on the bulk surface, and the generation of flake crystals on the bulk surface is suppressed to increase the specific surface area of the crystal particles. It has been concluded that the positive electrode resistance can be reduced by reducing the hydrogen concentration gradient on the bulk surface by reducing the value.
【００１８】本発明の解決しようとする課題は、ニッケ
ル水素蓄電池やニカド電池等のニッケル系蓄電池の正極
材料として、高い出力が得られ、充電時の水の電解副反
応による充電受入性が低下することもなく、しかも導電
性を付与するための高価なコバルト酸化物の添加量も減
らして材料コストの低廉化が図れるニッケル正極活物質
を提供することにある。The problem to be solved by the present invention is that a high output is obtained as a positive electrode material of a nickel-based storage battery such as a nickel-metal hydride storage battery or a nickel-cadmium battery, and the charge acceptability by the electrolytic secondary reaction of water during charging is reduced. An object of the present invention is to provide a nickel positive electrode active material that can be manufactured without reducing the amount of expensive cobalt oxide for imparting conductivity and reducing the material cost.
【００１９】[0019]
【課題を解決するための手段】この課題を解決するため
に本発明のニッケル正極活物質は、ニッケル系蓄電池の
正極に用いられる水酸化ニッケル微粒子を主成分とする
ニッケル正極活物質であって、水酸化ニッケル微粒子の
粒子径と比表面積との積が、５０μｍ・ｍ２／ｇ以下で
あることを要旨とするものである。Means for Solving the Problems To solve this problem, a nickel positive electrode active material of the present invention is a nickel positive electrode active material mainly composed of nickel hydroxide fine particles used for a positive electrode of a nickel-based storage battery, The gist is that the product of the particle size of the nickel hydroxide fine particles and the specific surface area is 50 μm · m 2 / g or less.
【００２０】この場合に水酸化ニッケル微粒子の粒子径
と比表面積との積の値は小さい程良いが、できれば３０
μｍ・ｍ２／ｇ以下であることが望ましく、粒子径５μ
ｍ以下、比表面積６ｍ２／ｇ以下であることが最も望ま
しい。そうすれば、活物質のバルク表面積を大きくし、
かつバルク表面の水素濃度勾配を小さくすることができ
て、そのバルク表面での水素移動量の確保と正極抵抗の
減少により高出力が得られることとなる。In this case, the smaller the product of the particle diameter of the nickel hydroxide fine particles and the specific surface area, the better, but if possible, 30
μm · m 2 / g or less, and a particle diameter of 5 μm.
Most preferably, the specific surface area is 6 m 2 / g or less. This will increase the bulk surface area of the active material,
In addition, the hydrogen concentration gradient on the bulk surface can be reduced, and high output can be obtained by securing the amount of hydrogen transfer on the bulk surface and reducing the positive electrode resistance.
【００２１】また、正極抵抗の減少により効率良く充電
反応が起きるため充電時の正極電位が卑にシフトし、そ
のために正極の充電電位が水の電解電位から離れて、酸
素を発生させる水の電解反応が生じることもなくなり、
充電受入性も向上することになる。In addition, since the charging reaction occurs efficiently due to the decrease in the positive electrode resistance, the positive electrode potential at the time of charging shifts to a low level. No reaction occurs,
The charge acceptability will also be improved.
【００２２】更に、水酸化ニッケル微粒子の比表面積が
規制されるために導電性を付与するための高価な酸化コ
バルト（ＣｏＯ）の添加量も少なくて済むことになる。Further, since the specific surface area of the nickel hydroxide fine particles is restricted, the amount of expensive cobalt oxide (CoO) for imparting conductivity can be reduced.
【００２３】図１は、本発明に係る水酸化ニッケル正極
活物質の表面形態を模式的に示したものである。この正
極活物質では、片状結晶の水酸化ニッケルの生成が抑制
されている。また図２は、この正極活物質の放電反応が
起きるバルク表面（Ｄ点）と活物質内部（Ｅ点）との水
素拡散濃度の変化を図示したものである。FIG. 1 schematically shows the surface morphology of the nickel hydroxide positive electrode active material according to the present invention. In this positive electrode active material, generation of nickel hydroxide in flaky crystals is suppressed. FIG. 2 illustrates changes in the hydrogen diffusion concentration between the bulk surface (point D) and the inside of the active material (point E) where the discharge reaction of the positive electrode active material occurs.
【００２４】この図２において放電反応が起きるバルク
表面（Ｄ点）と活物質内部（Ｅ点）との間で水素の拡散
が起きるが、このときＤで示したバルク表面の面積が大
きくなるため、Ｄ点の水素濃度の傾きが小さくても（言
い換えると、Ｄ点の水素濃度がＥ点の水素濃度にかなり
近い値でも）十分の量の水素の移動量が生じる。そして
このように、Ｄ点で示した面の面積が大きいため水素の
供給が速やかに行われ、正極としての出力密度が高くな
る。In FIG. 2, hydrogen is diffused between the bulk surface (point D) where the discharge reaction occurs and the inside of the active material (point E). At this time, since the area of the bulk surface indicated by D becomes large, Even if the gradient of the hydrogen concentration at the point D is small (in other words, even if the hydrogen concentration at the point D is fairly close to the hydrogen concentration at the point E), a sufficient amount of hydrogen transfer occurs. As described above, since the area of the surface indicated by the point D is large, the supply of hydrogen is promptly performed, and the output density as the positive electrode is increased.
【００２５】また、Ｄ点の水素濃度がＥ点の水素濃度に
近いため、充電時には従来の活物質を使用した場合に比
べて、図３に示したように正極電位がマイナス（−）側
にシフトして正極電位が卑な値に保たれるため、高温時
に副反応として生じる水の電解（酸素発生）が抑制さ
れ、充電受入性が向上する。更に、表面積が小さいた
め、小粒子径の活物質粒子を用いても１０ｍａｓｓ％の
ＣｏＯの添加によって十分の厚さのオキシ水酸化コバル
ト層が形成される。Further, since the hydrogen concentration at point D is close to the hydrogen concentration at point E, the positive electrode potential becomes negative (-) as shown in FIG. 3 during charging, as compared with the case where a conventional active material is used. The positive electrode potential is shifted to be kept at a low value, so that electrolysis of water (oxygen generation) generated as a side reaction at a high temperature is suppressed, and charge acceptability is improved. Further, since the surface area is small, even if active material particles having a small particle diameter are used, a cobalt oxyhydroxide layer having a sufficient thickness can be formed by adding 10 mass% of CoO.
【００２６】尚、この場合に正極活物質である「水酸化
ニッケル微粒子」の製造方法としては、前述の特開平１
０−７４５１４号公報に示されるように、アンモニウム
イオンを含むアルカリ水溶液（例えば、硫酸アンモニウ
ムやアンモニウム水溶液）を高速で攪拌しながら、その
水溶液に硝酸ニッケルや硫酸ニッケル等のニッケル塩溶
液を滴下し、ｐＨ調整剤である水酸化ナトリウム水溶液
も同時に滴下することにより水酸化ニッケルの結晶粒子
を析出させるものが一例として挙げられる。この場合に
はアンモニウムイオンを含むアルカリ水溶液の攪拌速度
としては、攪拌翼の回転速度が１２００ｒｐｍ以上であ
ることが望ましい。攪拌翼の回転速度が遅いと結晶粒子
の粒子径が大きくなり、活物質のバルク表面に片状結晶
が晶析するので好ましくない。In this case, the method for producing the “nickel hydroxide fine particles” as the positive electrode active material is described in
As disclosed in JP-A No. 0-74514, a nickel salt solution such as nickel nitrate or nickel sulfate is dropped into an aqueous alkali solution containing ammonium ions (eg, ammonium sulfate or ammonium aqueous solution) while stirring the solution at high speed. An example is one in which a sodium hydroxide aqueous solution as a regulator is also added dropwise to precipitate crystal particles of nickel hydroxide. In this case, as the stirring speed of the alkaline aqueous solution containing ammonium ions, the rotation speed of the stirring blade is desirably 1200 rpm or more. If the rotation speed of the stirring blade is low, the particle diameter of the crystal particles increases, and flake crystals are crystallized on the bulk surface of the active material, which is not preferable.
【００２７】[0027]
【発明の実施の形態】以下に本発明の実施例を詳細に説
明する。供試サンプルとして本発明品である正極活物質
（実施例１）と、比較品である市販の正極活物質（比較
例１）とを準備した。本発明品の正極活物質（実施例
１）の平均半径は４μｍ、比表面積は５．８ｍ２／ｇ
（両者の積は、２４μｍ・ｍ２／ｇ）であり、比較品の
正極活物質（比較例１）の平均粒子径は１２μｍ、比表
面積は１７ｍ２／ｇ（両者の積は約２００μｍ・ｍ２／
ｇ）である。ここで、正極活物質の平均粒子径は走査型
電子顕微鏡（ＳＥＭ）による粒子径写真から求め、比表
面積の値はＢＥＴ法により測定した。DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail. A positive electrode active material of the present invention (Example 1) and a commercially available positive electrode active material of a comparative product (Comparative Example 1) were prepared as test samples. The average radius of the positive electrode active material (Example 1) of the present invention was 4 μm, and the specific surface area was 5.8 m 2 / g.
(The product of both is 24 μm · m 2 / g), the average particle diameter of the positive electrode active material of the comparative product (Comparative Example 1) is 12 μm, and the specific surface area is 17 m 2 / g (the product of both is approximately 200 μm · m). 2 /
g). Here, the average particle diameter of the positive electrode active material was determined from a particle diameter photograph by a scanning electron microscope (SEM), and the value of the specific surface area was measured by a BET method.
【００２８】次に、本発明品である正極活物質（実施例
１）は、次のような方法で合成した。すなわち、容器
（ビーカー）に４Ｍのアンモニウム水溶液２００ｍｌを
入れ、攪拌棒（翼）により１２００ｒｐｍ以上の回転数
で攪拌しながら、これに２Ｍの硫酸ニッケル（ＮｉＳＯ
４）水溶液、及び４Ｍの水酸化ナトリウム（ＮａＯＨ）
水溶液をそれぞれ毎分０．４６ｍｌ添加する。これによ
り本発明品の正極活物質である水酸化ニッケルの晶析物
が得られた。Next, the positive electrode active material (Example 1) of the present invention was synthesized by the following method. That is, 200 ml of a 4M aqueous ammonium solution was placed in a container (beaker), and stirred with a stirring rod (blade) at a rotation speed of 1200 rpm or more.
4 ) Aqueous solution and 4M sodium hydroxide (NaOH)
0.46 ml of the aqueous solution is added each minute. As a result, a crystallized product of nickel hydroxide as the positive electrode active material of the product of the present invention was obtained.
【００２９】次いで、本発明品及び比較品の正極活物質
（４５ｇ）に対して、それぞれ酸化コバルト（ＣｏＯ）
粉末５ｇと２ｍａｓｓ％のメチルセルロース溶液１７ｇ
とを加えて活物質ペーストを作製し、これらの活物質ペ
ーストを４．６ｃｍ×５４ｃｍ角のＮｉフェルト集電体
の空孔内にそれぞれ充填（充填量は、およそ３０ｇ）
し、乾燥した後プレスして本発明品と比較品の正極を作
製する。Next, cobalt oxide (CoO) was added to the positive electrode active materials (45 g) of the product of the present invention and the comparative product, respectively.
5 g of powder and 17 g of 2 mass% methylcellulose solution
To prepare active material pastes, and these active material pastes are respectively filled into pores of a 4.6 cm × 54 cm square Ni felt current collector (filling amount is about 30 g).
After drying, pressing is performed to produce positive electrodes of the present invention and comparative products.
【００３０】また負極には、ＡＢ５系の水素吸蔵合金粉
末６０ｇに対して、２ｍａｓｓ％のメチルセルロース溶
液を２０ｇ加えて負極活物質のペーストを作製し、この
負極活物質のペーストを発泡Ｎｉ集電体に担持して２枚
の負極を作製した。そして、これら正極と負極とをセパ
レータを介して巻き取り、集電板を溶接後、封缶して容
量約６．５Ａｈの電池を２個作製した。電解液には、
６．８Ｍ水酸化カリウム＋０．８Ｍ水酸化リチウム溶液
を注液している。Further the negative electrode, AB for the 5 system hydrogen absorbing alloy powder 60g of to prepare a 2mass% methylcellulose solution 20g addition of the negative electrode active material paste, a paste of the negative electrode active material foamed Ni current collector Two sheets of the negative electrode were produced by being carried on a body. Then, the positive electrode and the negative electrode were wound up with a separator interposed therebetween, and the current collector plate was welded and sealed to produce two batteries having a capacity of about 6.5 Ah. In the electrolyte,
6.8 M potassium hydroxide + 0.8 M lithium hydroxide solution is injected.
【００３１】次に、このようにして製作したニッケル水
素蓄電池（本発明品と比較品）について充放電試験を行
ったので、その結果を説明する。この充放電試験は、２
０℃の恒温槽内で行い、充電は１／３Ｃの電流値で１１
０％の電気量となるまで行い、次いで３０分の休止後、
１／３Ｃの電流で電池端子電圧が０．９Ｖとなるまで放
電した。そして、充放電試験を１００サイクル行った
後、電流−電圧特性を求め、その傾きから電池の出力密
度を算出した。また、６０℃において上記条件で３回連
続して充放電を行い、３回目の放電量から充電受入性を
評価した。これらの結果を表１に示す。Next, a charge / discharge test was performed on the nickel-metal hydride storage batteries (products of the present invention and comparative products) manufactured as described above, and the results will be described. This charge / discharge test
It is performed in a constant temperature bath at 0 ° C.
Perform until the amount of electricity reaches 0%, then after a 30 minute pause,
The battery was discharged at a current of 1 / 3C until the battery terminal voltage became 0.9V. After 100 cycles of the charge / discharge test, the current-voltage characteristics were determined, and the output density of the battery was calculated from the slope. Charge and discharge were performed three times continuously at 60 ° C. under the above conditions, and charge acceptability was evaluated from the third discharge amount. Table 1 shows the results.
【００３２】[0032]
【表１】 [Table 1]
【００３３】しかして、この表１に示したように、市販
の正極活物質を用いた比較電池の出力密度３５０Ｗ／ｋ
ｇに比べて、小粒子径で比表面積の小さな正極活物質を
使用した本発明電池では、５００Ｗ／ｋｇと出力密度が
高く、また高温での充電受入性も格段に改善されている
ことが分かる。ちなみに、充電受入性が比較電池におい
て３５％ということは、残り６５％は水の電解による酸
素発生により電流損失が生じていることを意味する。As shown in Table 1, the output density of a comparative battery using a commercially available positive electrode active material was 350 W / k.
The battery of the present invention using the positive electrode active material having a small particle diameter and a small specific surface area as compared with g has a high output density of 500 W / kg and also has a remarkably improved charge acceptability at high temperatures. . Incidentally, the fact that the charge acceptability is 35% in the comparative battery means that the remaining 65% has a current loss due to the generation of oxygen by electrolysis of water.
【００３４】図３は、これをグラフに示したもので、横
軸に正極電位を採り、縦軸に電流値を採ったものである
が、温度が高い場合の充電時の正極の電位−電流曲線
（Ａ）と水の電解による酸素発生反応の電位−電流曲線
（Ｂ）とが近接する。従来の活物質では、酸素発生の副
反応が起こるものを、本発明の正極活物質によれば、そ
の正極電位−電流曲線が曲線（Ｃ）、つまり正極電位の
マイナス（卑）側にシフトして酸素発生の副反応が抑制
されるものである。従来採られている対策として、正極
活物質に添加剤を加える等して曲線（Ｂ）を曲線（Ｄ）
にシフトさせて酸素発生の副反応を抑制する考えは既に
あるが、これによれば充電反応も抑制されるために本発
明の方が優れている。FIG. 3 is a graph showing this, in which the horizontal axis indicates the positive electrode potential and the vertical axis indicates the current value. The potential of the positive electrode during charging when the temperature is high-current The curve (A) and the potential-current curve (B) of the oxygen generation reaction by electrolysis of water are close to each other. According to the positive electrode active material of the present invention, the positive electrode active material of the present invention shifts the positive electrode potential-current curve to the curve (C), that is, the negative (base) side of the positive electrode potential. Thus, side reactions of oxygen generation are suppressed. As a conventional measure, the curve (B) is changed to the curve (D) by adding an additive to the positive electrode active material.
There is already a concept of suppressing the side reaction of oxygen generation by shifting to the above, but according to this, the charging reaction is also suppressed, so that the present invention is superior.
【００３５】本発明は上記した実施の形態に何等限定さ
れるものではなく、本発明の趣旨を逸脱しない範囲で種
々の改変が可能である。例えば、上記実施例では、放電
リザーブのための水酸化コバルトを本発明品の水酸化ニ
ッケル活物質生成後に配合しているが、水酸化ニッケル
活物質の生成段階で同時に行うようにしても良い。この
場合には、アンモニウム水溶液（或いは硫酸アンモニウ
ム水溶液）に、硫酸ニッケルと硫酸コバルトの混合溶液
を水酸化ナトリウム水溶液と共に滴下して水酸化ニッケ
ルと水酸化コバルトとの共析物を生成することになる。The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the cobalt hydroxide for the discharge reserve is added after the nickel hydroxide active material of the present invention is formed, but it may be performed simultaneously with the step of generating the nickel hydroxide active material. In this case, a mixed solution of nickel sulfate and cobalt sulfate is dropped together with an aqueous solution of sodium hydroxide to an aqueous solution of ammonium (or an aqueous solution of ammonium sulfate) to produce an eutectoid of nickel hydroxide and cobalt hydroxide.
【００３６】[0036]
【発明の効果】本発明のニッケル正極活物質によれば、
水酸化ニッケル微粒子の表面に水酸化ニッケルの片状結
晶もなく粒子径と比表面積との積を５０μｍ・ｍ２／ｇ
以下に抑えたものであるから、ニッケル水素蓄電池等の
正極材料に用いたときに高い出力が得られ、また充電受
入性にも優れる。しかも放電リザーブのためのコバルト
配合量も少なくて済み、急速充電や過放電に強く、長期
間安定した出力が得られる等の電池性能を備えるもので
あるから、携帯電話やノートパソコン、更にはハイブリ
ッド車を初めとする自動車用電源等の用途への適用が大
いに期待されるものである。According to the nickel positive electrode active material of the present invention,
There is no flake crystal of nickel hydroxide on the surface of the nickel hydroxide fine particles and the product of the particle diameter and the specific surface area is 50 μm · m 2 / g.
Since the content is suppressed below, a high output is obtained when used for a positive electrode material of a nickel-metal hydride storage battery or the like, and the charge acceptability is excellent. In addition, the amount of cobalt used for the discharge reserve is small, and it is resistant to rapid charging and overdischarge, and has battery performance such as stable output for a long period of time. It is highly expected to be applied to applications such as power sources for vehicles such as cars.
【図１】本発明に係るニッケル正極活物質の表面形態を
模式的に示した図である。FIG. 1 is a diagram schematically showing the surface morphology of a nickel positive electrode active material according to the present invention.
【図２】図１に示した本発明の正極活物質の各位置（Ｄ
点、Ｅ点）における水素（Ｈ）濃度の変化を説明した図
である。FIG. 2 shows each position (D) of the cathode active material of the present invention shown in FIG.
FIG. 4 is a diagram for explaining a change in hydrogen (H) concentration at points (point E and point E).
【図３】本発明に係るニッケル正極活物質を用いたこと
による充電受入性（高温時）の改善を説明したものであ
る。FIG. 3 illustrates the improvement of charge acceptability (at high temperature) by using the nickel positive electrode active material according to the present invention.
【図４】比較品である片状結晶を有するニッケル正極活
物質の表面形態を模式的に示した図である。FIG. 4 is a view schematically showing a surface morphology of a nickel positive electrode active material having a flaky crystal as a comparative product.
【図５】図４に示した比較品の正極活物質の各位置（Ａ
点、Ｂ点、Ｃ点）における水素（Ｈ）濃度の変化を説明
した図である。5 shows positions (A) of the positive electrode active material of the comparative product shown in FIG.
FIG. 5 is a diagram illustrating a change in hydrogen (H) concentration at points (points B and C).
───────────────────────────────────────────────────── フロントページの続き (72)発明者 砥綿 真一 愛知県愛知郡長久手町大字長湫字横道41番 地の１ 株式会社豊田中央研究所内 (72)発明者 近藤 康仁 愛知県愛知郡長久手町大字長湫字横道41番 地の１ 株式会社豊田中央研究所内 (72)発明者 磯貝 嘉宏 愛知県刈谷市豊田町２丁目１番地 株式会 社豊田自動織機製作所内 (72)発明者 藤田 勝義 愛知県刈谷市豊田町２丁目１番地 株式会 社豊田自動織機製作所内 (72)発明者 牟田 光治 愛知県刈谷市豊田町２丁目１番地 株式会 社豊田自動織機製作所内 Ｆターム(参考） 5H028 HH00 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichi Towa 41-1, Chuchu-Yokomichi, Oku-cho, Nagakute-cho, Aichi-gun Aichi, Japan Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Yasuhito Kondo Nagakute-cho, Aichi-gun, Aichi No. 41, Yokomichi, Chuchu, 1 Inside Toyota Central Research Institute, Inc. (72) Inventor Yoshihiro Isogai 2-1-1, Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Katsuyoshi Fujita Kariya-shi, Aichi Prefecture 2-1-1, Toyota-machi In Toyota Industries Corporation (72) Inventor Koji Muta 2-1-1, Toyota-machi, Kariya City, Aichi Prefecture F-term in Toyota Industries Corporation (reference) 5H028 HH00
Claims (1)
酸化ニッケル微粒子を主成分とするニッケル正極活物質
であって、水酸化ニッケル微粒子の粒子径と比表面積と
の積が、５０μｍ・ｍ２／ｇ以下であることを特徴とす
るニッケル正極活物質。1. A nickel positive electrode active material mainly composed of nickel hydroxide fine particles used for a positive electrode of a nickel-based storage battery, wherein the product of the particle diameter of the nickel hydroxide fine particles and the specific surface area is 50 μm · m 2 / g or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31301398A JP3506365B2 (en) | 1998-11-04 | 1998-11-04 | Nickel positive electrode active material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31301398A JP3506365B2 (en) | 1998-11-04 | 1998-11-04 | Nickel positive electrode active material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000149938A true JP2000149938A (en) | 2000-05-30 |
| JP3506365B2 JP3506365B2 (en) | 2004-03-15 |
Family
ID=18036187
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31301398A Expired - Fee Related JP3506365B2 (en) | 1998-11-04 | 1998-11-04 | Nickel positive electrode active material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3506365B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002208400A (en) * | 2000-11-09 | 2002-07-26 | Toyota Central Res & Dev Lab Inc | Nickel hydroxide for positive electrode active material of alkaline secondary battery, alkaline secondary battery using same, its characteristics evaluation method and manufacturing method |
| JP2010238671A (en) * | 2010-06-15 | 2010-10-21 | Sony Corp | Alkaline zinc battery |
| JP2012176888A (en) * | 2012-04-23 | 2012-09-13 | Univ Of Miyazaki | Nickel hydroxide nanosheet and manufacturing method thereof |
-
1998
- 1998-11-04 JP JP31301398A patent/JP3506365B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002208400A (en) * | 2000-11-09 | 2002-07-26 | Toyota Central Res & Dev Lab Inc | Nickel hydroxide for positive electrode active material of alkaline secondary battery, alkaline secondary battery using same, its characteristics evaluation method and manufacturing method |
| JP4498647B2 (en) * | 2000-11-09 | 2010-07-07 | 株式会社豊田中央研究所 | Nickel hydroxide for positive electrode active material of alkaline secondary battery, alkaline secondary battery using the same, characteristic evaluation method thereof, and production method thereof |
| JP2010238671A (en) * | 2010-06-15 | 2010-10-21 | Sony Corp | Alkaline zinc battery |
| JP2012176888A (en) * | 2012-04-23 | 2012-09-13 | Univ Of Miyazaki | Nickel hydroxide nanosheet and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3506365B2 (en) | 2004-03-15 |
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