JP2002211931A - Lithium nickel compound oxide for active material for positive electrode of lithium secondary battery - Google Patents
Lithium nickel compound oxide for active material for positive electrode of lithium secondary batteryInfo
- Publication number
- JP2002211931A JP2002211931A JP2001002618A JP2001002618A JP2002211931A JP 2002211931 A JP2002211931 A JP 2002211931A JP 2001002618 A JP2001002618 A JP 2001002618A JP 2001002618 A JP2001002618 A JP 2001002618A JP 2002211931 A JP2002211931 A JP 2002211931A
- Authority
- JP
- Japan
- Prior art keywords
- lithium
- nickel composite
- composite oxide
- positive electrode
- active material
- 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.)
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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、リチウムの吸蔵・
脱離現象を利用したリチウム二次電池を構成することの
できる正極活物質用リチウムニッケル複合酸化物に関す
る。TECHNICAL FIELD The present invention relates to a method for storing and storing lithium.
The present invention relates to a lithium nickel composite oxide for a positive electrode active material, which can constitute a lithium secondary battery utilizing a desorption phenomenon.
【０００２】[0002]
【従来の技術】リチウムの吸蔵・脱離現象を利用したリ
チウム二次電池は、高エネルギー密度であることから、
携帯電話、パソコン等の小型化に伴い、通信機器、情報
関連機器の分野で広く普及するに至っている。一方で、
環境問題、資源問題から、自動車の分野でも電気自動車
の開発が急がれており、この電気自動車用の電源として
も、リチウム二次電池が検討されている。2. Description of the Related Art Lithium secondary batteries utilizing the insertion and extraction of lithium have a high energy density.
With the miniaturization of mobile phones, personal computers, and the like, they have become widespread in the field of communication devices and information-related devices. On the other hand,
Due to environmental issues and resource issues, the development of electric vehicles is urgently required in the field of automobiles, and lithium secondary batteries are being studied as power sources for electric vehicles.
【０００３】このように広い分野での要望があるリチウ
ム二次電池であるが、その価格が高いことから、他の二
次電池にも増して長寿命であることが要求される。長寿
命であるための要件の一つとして、充電率を高く保持し
た状態でリチウム二次電池を保存した場合にも、容量が
減少しない、電池の内部抵抗が上昇しないといった、い
わゆる保存特性が良好であることが要求される。特に、
高温下では電池反応が活性化し容量の減少等も大きいこ
とから、例えば屋外放置される可能性のある電気自動車
用電源等の用途にリチウム二次電池を使用することを想
定した場合には、高温下での保存特性が良好であること
が重要な特性の一つとなる。[0003] Lithium secondary batteries are demanded in such a wide field, but due to their high price, they are required to have a longer life than other secondary batteries. One of the requirements for long life is that when a lithium secondary battery is stored while maintaining a high charge rate, the so-called storage characteristics such as the capacity does not decrease and the internal resistance of the battery does not increase are good. Is required. In particular,
At high temperatures, the battery reaction is activated and the capacity is greatly reduced.For example, if it is assumed that a lithium secondary battery is used for an electric vehicle power supply that may be left outdoors, a high temperature One of the important characteristics is that the storage characteristics below are good.
【０００４】現在では、Ｎｉ、Ｃｏを主構成元素とする
リチウム遷移金属複合酸化物を正極活物質に用いて構成
するリチウム二次電池の開発が進められているが、この
ようなリチウム二次電池は、充電率を高く保持した状態
で保存した場合に電池の容量の減少や内部抵抗の上昇が
大きく、保存特性、特に高温下での保存特性に問題があ
った。At present, development of a lithium secondary battery using a lithium-transition metal composite oxide containing Ni and Co as main constituent elements as a positive electrode active material is in progress. However, when the battery is stored in a state where the charge rate is maintained at a high level, the capacity of the battery is greatly reduced and the internal resistance is greatly increased, and there is a problem in the storage characteristics, particularly, the storage characteristics at high temperatures.
【０００５】保存特性の向上させる試みとして、例え
ば、特開平９−１７４４６号公報や特開平９−９２３２
９号公報には電解液の溶媒を特定の組成にすることが示
されている。また、特開平９−１９９１２６号公報では
負極活物質を改良することが示されている。しかし、上
記試みでは、Ｎｉ、Ｃｏを主構成元素とするリチウム遷
移金属複合酸化物を正極活物質に用いて構成するリチウ
ム二次電池の保存特性は充分なものとはいえない。[0005] As an attempt to improve the storage characteristics, for example, Japanese Patent Application Laid-Open Nos. 9-17446 and 9-9232 disclose the method.
No. 9 discloses that a solvent of an electrolytic solution has a specific composition. Japanese Patent Application Laid-Open No. 9-199126 discloses improvement of a negative electrode active material. However, in the above attempts, the storage characteristics of a lithium secondary battery formed using a lithium transition metal composite oxide containing Ni and Co as main constituent elements as a positive electrode active material cannot be said to be sufficient.
【０００６】[0006]
【発明が解決しようとする課題】本発明者が検討を重ね
た結果、上記リチウム二次電池の保存による容量の減
少、内部抵抗の上昇は、充電により正極電位が上昇し、
その状態が長期間保持されることで、正極活物質である
リチウム遷移金属複合酸化物と電解液とが反応し、電解
液が分解することが原因の一つであることがわかった。
また、正極では、充電によってリチウムがリチウム遷移
金属複合酸化物から脱離するため、その状態が長期間保
持されることにより、リチウム遷移金属複合酸化物の結
晶構造が崩壊することも原因の一つと考えられる。As a result of repeated studies by the present inventor, the decrease in capacity and the increase in internal resistance due to the storage of the above lithium secondary battery are caused by the fact that the positive electrode potential increases due to charging,
It has been found that one of the causes is that the lithium-transition metal composite oxide, which is a positive electrode active material, reacts with the electrolyte when the state is maintained for a long time, and the electrolyte is decomposed.
In addition, in the positive electrode, lithium is desorbed from the lithium-transition metal composite oxide by charging, and one of the causes is that the crystal structure of the lithium-transition metal composite oxide is collapsed by maintaining the state for a long time. Conceivable.
【０００７】本発明は、上記知見に基づいたものであ
り、正極活物質の結晶構造を安定化するとともに、正極
活物質と電解液との反応を抑制することで、充電状態で
長期間保存しても容量の減少および内部抵抗の上昇が少
ないリチウム二次電池を構成することのできる正極活物
質用リチウムニッケル複合酸化物を提供することを課題
とする。The present invention is based on the above findings and stabilizes the crystal structure of the positive electrode active material and suppresses the reaction between the positive electrode active material and the electrolyte so that the battery can be stored for a long time in a charged state. It is an object of the present invention to provide a lithium-nickel composite oxide for a positive electrode active material that can constitute a lithium secondary battery in which a decrease in capacity and a rise in internal resistance are small.
【０００８】[0008]
【課題を解決するための手段】本発明のリチウム二次電
池正極活物質用リチウムニッケル複合酸化物は、組成式
ＬｉＮｉ1-x-yＣｏxＡｌyＯ2（０．１≦ｘ≦０．２；
０．０５≦ｙ≦０．１）で表され、平均粒径が１μｍ以
上４μｍ以下の１次粒子が凝集して２次粒子を形成した
粒子構造をもつことを特徴とする。The lithium nickel composite oxide for a positive electrode active material of a lithium secondary battery according to the present invention has a composition formula of LiNi 1-xy Co x Al y O 2 (0.1 ≦ x ≦ 0.2;
0.05 ≦ y ≦ 0.1), and has a particle structure in which primary particles having an average particle diameter of 1 μm or more and 4 μm or less are aggregated to form secondary particles.
【０００９】つまり、本発明のリチウムニッケル複合酸
化物は、理論容量が大きくかつ比較的安価であるという
観点からＮｉを主構成要素とし、役割の異なる２種の元
素（Ｃｏ、Ａｌ）でＮｉサイトの一部を置換したものと
なっている。In other words, the lithium-nickel composite oxide of the present invention has Ni as its main constituent element from the viewpoint of a large theoretical capacity and is relatively inexpensive, and has a Ni site composed of two elements (Co and Al) having different roles. Has been partially replaced.
【００１０】Ｃｏは、主に、リチウムニッケル複合酸化
物の結晶構造を安定化する役割を果たす。リチウムニッ
ケル複合酸化物の結晶構造の安定化による保存特性の改
善効果を充分に発揮させるために、Ｃｏの置換割合、つ
まり組成式におけるｘの値は０．１≦ｘ≦０．２とす
る。さらに、Ｃｏは、元素置換による容量の減少を抑え
るとともに、Ｌｉ（Ｃｏ，Ｎｉ）Ｏ2は全固溶型であ
り、結晶性の低下を最小限にとどめるという利点を有す
る。[0010] Co mainly serves to stabilize the crystal structure of the lithium nickel composite oxide. In order to sufficiently exhibit the effect of improving storage characteristics by stabilizing the crystal structure of the lithium nickel composite oxide, the substitution ratio of Co, that is, the value of x in the composition formula, is set to 0.1 ≦ x ≦ 0.2. Further, Co has the advantage of suppressing a decrease in capacity due to elemental substitution, and Li (Co, Ni) O 2 being an all-solid solution type, which minimizes the decrease in crystallinity.
【００１１】Ａｌは、主に、酸素放出に伴う活物質の分
解反応を抑え、熱安定性を向上させるという役割を果た
す。リチウムニッケル複合酸化物の熱安定性の向上によ
る保存特性の改善効果を充分に発揮させるために、Ａｌ
の置換割合、つまり組成式におけるｙの値は、０．０５
≦ｙ≦０．１とする。さらに、Ａｌは、熱安定性を向上
させつつ、容量低下を最小限に抑えるという利点を有す
る。[0011] Al plays a role mainly in suppressing the decomposition reaction of the active material accompanying the release of oxygen and improving the thermal stability. In order to sufficiently exert the effect of improving the storage characteristics by improving the thermal stability of the lithium nickel composite oxide, Al
, That is, the value of y in the composition formula is 0.05
≦ y ≦ 0.1. Further, Al has the advantage of minimizing capacity loss while improving thermal stability.
【００１２】したがって、適正量のＣｏ、Ａｌで置換す
ることにより、本発明のリチウムニッケル複合酸化物
は、電池を充電状態で長期間保存した場合であっても、
結晶構造が崩壊することのない、安定したリチウムニッ
ケル複合酸化物となる。Therefore, by substituting appropriate amounts of Co and Al, the lithium-nickel composite oxide of the present invention can be used even when the battery is stored in a charged state for a long time.
A stable lithium-nickel composite oxide without crystal structure collapse is obtained.
【００１３】また、一般に、リチウムニッケル複合酸化
物は、略単結晶に近い粒子である１次粒子が凝集して２
次粒子を形成する粒子構造を有している。そして、リチ
ウムニッケル複合酸化物を正極活物質として用いる場合
には、粉末状のリチウムニッケル複合酸化物に導電材お
よび結着剤を混合し、ペースト状の正極合材としたもの
を、集電体表面に塗布等することによって正極を形成す
る。したがって、活物質である粉末状のリチウムニッケ
ル複合酸化物は、粉末粒子を構成する１次粒子の粒子径
が小さいほど比表面積が大きくなる。つまり、１次粒子
の粒子径が小さいほど、リチウムニッケル複合酸化物に
おける電解液との反応に関与する表面積が大きくなるた
め、電解液の分解反応が進行しやすいと考えられる。In general, a lithium nickel composite oxide is formed by aggregating primary particles, which are particles substantially close to a single crystal, into two particles.
It has a particle structure that forms secondary particles. When a lithium nickel composite oxide is used as the positive electrode active material, a paste of the positive electrode mixture obtained by mixing a conductive material and a binder with the powdery lithium nickel composite oxide is used as a current collector. A positive electrode is formed by coating or the like on the surface. Therefore, the specific surface area of the powdery lithium nickel composite oxide as the active material increases as the particle diameter of the primary particles constituting the powder particles decreases. In other words, it is considered that the smaller the particle diameter of the primary particles, the larger the surface area of the lithium nickel composite oxide involved in the reaction with the electrolytic solution, so that the decomposition reaction of the electrolytic solution is likely to proceed.
【００１４】本発明のリチウムニッケル複合酸化物は、
二次粒子を構成する１次粒子が平均粒径で１μｍ以上４
μｍ以下という大きな粒子径を有しているため、電解液
との反応に関与する表面積が小さくなり、その結果、電
解液の分解反応を抑制できると考えられる。つまり、本
発明のリチウムニッケル複合酸化物は、Ｎｉサイトを適
正量のＣｏおよびＡｌにより置換し、かつ粒子構造にお
ける１次粒子の粒子径を大きくすることにより、安定な
結晶構造を有し、かつ電解液との反応も少ないリチウム
ニッケル複合酸化物となる。[0014] The lithium nickel composite oxide of the present invention comprises:
The primary particles constituting the secondary particles have an average particle size of 1 μm or more and 4
It is thought that since the particles have a large particle diameter of μm or less, the surface area involved in the reaction with the electrolytic solution is reduced, and as a result, the decomposition reaction of the electrolytic solution can be suppressed. That is, the lithium nickel composite oxide of the present invention has a stable crystal structure by replacing Ni sites with appropriate amounts of Co and Al and increasing the particle diameter of primary particles in the particle structure, and A lithium nickel composite oxide that has little reaction with the electrolyte is obtained.
【００１５】したがって、本発明のリチウムニッケル複
合酸化物を正極活物質として用いた場合には、電池を充
電状態で長期間保存した場合であっても、電池容量を維
持することができ、かつ電池の内部抵抗の上昇も抑制さ
れるため、安価であり、かつ保存特性に優れたリチウム
二次電池を得ることができる。Therefore, when the lithium nickel composite oxide of the present invention is used as a positive electrode active material, the battery capacity can be maintained even when the battery is stored in a charged state for a long time, and the battery capacity can be maintained. Since the increase in the internal resistance of the lithium secondary battery is also suppressed, a lithium secondary battery that is inexpensive and has excellent storage characteristics can be obtained.
【００１６】[0016]
【発明の実施の形態】以下に、本発明のリチウム二次電
池正極活物質用リチウムニッケル複合酸化物について、
組成および粒子構造と製造方法とを説明し、その後に、
本発明のリチウムニッケル複合酸化物の利用形態である
リチウム二次電池について説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a lithium nickel composite oxide for a positive electrode active material of a lithium secondary battery of the present invention will be described.
Explain the composition and particle structure and manufacturing method, and then
A lithium secondary battery, which is an application of the lithium nickel composite oxide of the present invention, will be described.
【００１７】〈リチウムニッケル複合酸化物の組成およ
び粒子構造〉本発明のリチウムニッケル複合酸化物は、
組成式ＬｉＮｉ1-x-yＣｏxＡｌyＯ2（０．１≦ｘ≦０．
２；０．０５≦ｙ≦０．１）で表され、その結晶構造は
層状岩塩構造となっている。なお、本発明のリチウムニ
ッケル複合酸化物は、上記組成式で表される化学量論組
成のものだけでなく、一部の元素が欠損または過剰とな
る非化学量論組成のものをも含むものである。<Composition and particle structure of lithium nickel composite oxide> The lithium nickel composite oxide of the present invention
Compositional formula LiNi 1-xy Co x Al y O 2 (0.1 ≦ x ≦ 0.
2; 0.05 ≦ y ≦ 0.1), and its crystal structure is a layered rock salt structure. In addition, the lithium nickel composite oxide of the present invention includes not only the stoichiometric composition represented by the above composition formula, but also a non-stoichiometric composition in which some elements are missing or excessive. .
【００１８】Ｃｏの置換割合、つまり組成式におけるｘ
の値は０．１≦ｘ≦０．２とする。ｘ＜０．１の場合
は、Ｃｏの置換量が少ないために、結晶構造の安定化が
充分ではなく、反対に、ｘ＞０．２の場合は、Ｃｏの置
換量が多いために、ＮｉとＣｏの固溶状態が何らかの変
化を生じ、リチウムニッケル複合酸化物の結晶性が低下
するからである。特に、高温下での保存特性を考慮する
場合には、ｘの値は０．１２≦ｘ≦０．１７とすること
が望ましい。The substitution ratio of Co, that is, x in the composition formula
Is 0.1 ≦ x ≦ 0.2. In the case of x <0.1, the stabilization of the crystal structure is not sufficient because the amount of substitution of Co is small. Conversely, in the case of x> 0.2, the amount of substitution of Co is large, so that Ni This is because some change occurs in the solid solution state of Co and Co, and the crystallinity of the lithium nickel composite oxide decreases. In particular, in consideration of storage characteristics at high temperatures, it is desirable that the value of x be 0.12 ≦ x ≦ 0.17.
【００１９】また、Ａｌの置換割合、つまり組成式にお
けるｙの値は、０．０５≦ｙ≦０．１とする。ｙ＜０．
０５の場合は、Ａｌの置換量が少ないために、結晶構造
における熱安定性が充分ではなく、反対に、ｙ＞０．１
の場合は、Ａｌの置換量が多いために、放電容量が低下
するからである。特に、高温下での保存特性を考慮する
場合には、ｙの値は０．０６≦ｙ≦０．０８とすること
が望ましい。The substitution ratio of Al, that is, the value of y in the composition formula, is set to 0.05 ≦ y ≦ 0.1. y <0.
In the case of No. 05, since the substitution amount of Al is small, the thermal stability in the crystal structure is not sufficient, and conversely, y> 0.1
This is because, in the case of (1), the discharge capacity is reduced due to a large amount of Al substitution. In particular, in consideration of storage characteristics at high temperatures, it is desirable that the value of y be 0.06 ≦ y ≦ 0.08.
【００２０】本発明のリチウムニッケル複合酸化物は、
平均粒径が１μｍ以上４μｍ以下の１次粒子が凝集して
２次粒子を形成した粒子構造を有する。１次粒子が平均
粒径で１μｍ未満であると、電解液との反応に関与する
表面積が増加するため、電解液の分解反応が促進され、
電池の内部抵抗が上昇し、容量減少の原因となるからで
ある。反対に、４μｍを越えると、それに伴い２次粒子
も大きくなるため、均一に活物質が塗工された正極の作
製が困難となり、また正極合材の塗膜表面が平滑になり
にくくなるため電極間のショートの原因ともなり得るか
らである。なお、活物質が均一に塗工された正極を作製
するという観点等から、２次粒子の平均粒径は、５μｍ
以上３０μｍ以下であることが望ましい。[0020] The lithium nickel composite oxide of the present invention comprises:
It has a particle structure in which primary particles having an average particle size of 1 μm or more and 4 μm or less are aggregated to form secondary particles. When the primary particles have an average particle size of less than 1 μm, the surface area involved in the reaction with the electrolytic solution increases, so that the decomposition reaction of the electrolytic solution is promoted,
This is because the internal resistance of the battery increases and causes a reduction in capacity. Conversely, if the thickness exceeds 4 μm, the secondary particles also increase in size, making it difficult to produce a positive electrode coated with the active material uniformly, and the coating surface of the positive electrode mixture becomes difficult to be smooth, so that the electrode becomes difficult. This is because it may cause a short circuit. The average particle size of the secondary particles is 5 μm from the viewpoint of producing a positive electrode coated with the active material uniformly.
It is desirable that the thickness be at least 30 μm.
【００２１】なお、１次粒子および２次粒子の平均粒径
の簡単な測定法として、例えば、リチウムニッケル複合
酸化物の走査型電子顕微鏡（ＳＥＭ）写真を利用する方
法がある。すなわち、リチウムニッケル複合酸化物のＳ
ＥＭ写真を撮影し、その写真におけるリチウムニッケル
複合酸化物の１次粒子等の最長径とみなされる径と最短
径とみなされる径を測定する。そして、それら２つの値
の平均値をその１次粒子等の粒子径とみなして、それら
の平均を１次粒子等の平均粒径として採用すればよい。As a simple method for measuring the average particle size of the primary particles and the secondary particles, for example, there is a method using a scanning electron microscope (SEM) photograph of a lithium nickel composite oxide. That is, the lithium nickel composite oxide S
An EM photograph is taken, and the diameter of the primary particles and the like of the lithium nickel composite oxide in the photograph, which is regarded as the longest diameter and the shortest diameter, are measured. Then, the average value of these two values may be regarded as the particle size of the primary particles and the like, and the average thereof may be adopted as the average particle size of the primary particles and the like.
【００２２】〈リチウムニッケル複合酸化物の製造方
法〉本発明のリチウムニッケル複合酸化物は、その製造
方法を特に限定するものではないが、以下の方法によれ
ば、より簡便に製造することができる。すなわち、リチ
ウム源、ニッケル源、コバルト源、アルミニウム源とな
る各化合物を混合して混合物を得る原料混合工程と、前
記混合物を酸素雰囲気中で焼成する焼成工程とを含んで
構成される方法である。各工程における条件を適宜調整
することにより、所望の１次粒子の平均粒径を有するリ
チウムニッケル複合酸化物を製造することができる。以
下、各工程について説明する。<Production method of lithium-nickel composite oxide> Although the production method of the lithium-nickel composite oxide of the present invention is not particularly limited, it can be more easily produced by the following method. . That is, the method includes a raw material mixing step of mixing the respective compounds serving as a lithium source, a nickel source, a cobalt source, and an aluminum source to obtain a mixture, and a firing step of firing the mixture in an oxygen atmosphere. . By appropriately adjusting the conditions in each step, a lithium-nickel composite oxide having a desired average primary particle size can be produced. Hereinafter, each step will be described.
【００２３】（１）原料混合工程 本原料混合工程は、リチウム源となるリチウム化合物
と、ニッケル源となるニッケル化合物と、コバルト源と
なるコバルト化合物と、アルミニウム源となるアルミニ
ウム化合物とを混合して混合物を得る工程である。(1) Raw Material Mixing Step In the raw material mixing step, a lithium compound serving as a lithium source, a nickel compound serving as a nickel source, a cobalt compound serving as a cobalt source, and an aluminum compound serving as an aluminum source are mixed. This is a step of obtaining a mixture.
【００２４】リチウム源となるリチウム化合物として
は、酸化リチウム、水酸化リチウム、炭酸リチウム、硝
酸リチウム等を用いることができる。特に、比較的低融
点であることから水酸化リチウム、硝酸リチウムを用い
ることが望ましい。As the lithium compound serving as a lithium source, lithium oxide, lithium hydroxide, lithium carbonate, lithium nitrate and the like can be used. In particular, it is desirable to use lithium hydroxide and lithium nitrate because of their relatively low melting points.
【００２５】コバルト源となる化合物としては、水酸化
コバルト、炭酸コバルト、硝酸コバルト等を用いること
ができる。ニッケル源となるニッケル化合物としては、
水酸化ニッケル、炭酸ニッケル、硝酸ニッケル等を用い
ることができる。アルミニウム源となるアルミニウム化
合物としては、酸化アルミニウム、水酸化アルミニウ
ム、硝酸アルミニウム等を用いることができる。特に、
反応性が高いという理由から、水酸化コバルト、水酸化
ニッケルを、また、焼成時にガスが発生しないという理
由から、水酸化アルミニウム、酸化アルミニウムを用い
ることが望ましい。As a compound serving as a cobalt source, cobalt hydroxide, cobalt carbonate, cobalt nitrate and the like can be used. Nickel compounds serving as nickel sources include:
Nickel hydroxide, nickel carbonate, nickel nitrate and the like can be used. As an aluminum compound serving as an aluminum source, aluminum oxide, aluminum hydroxide, aluminum nitrate, or the like can be used. In particular,
It is desirable to use cobalt hydroxide and nickel hydroxide for the reason of high reactivity, and to use aluminum hydroxide and aluminum oxide for the reason that no gas is generated during firing.
【００２６】なお、コバルトはニッケルと全固溶体を形
成するため、ニッケルにコバルトが固溶したニッケル・
コバルト複合化合物を用いることが望ましい。特に、上
記水酸化コバルト、水酸化ニッケルを用いる場合には、
ニッケル・コバルト複合化合物を簡単に合成する方法と
して、例えば、水酸化ニッケルおよび水酸化コバルトを
水に溶解した水溶液を強アルカリ水溶液に滴下して、ニ
ッケル・コバルト水酸化物（以下、水酸化物という。）
を共沈させて合成する方法を用いることができる。この
方法によれば、リチウムニッケル複合酸化物の核となる
粒子の粒子径をコントロールすることができるため、所
望の１次粒子の粒子径に応じたリチウムニッケル複合酸
化物を容易に得ることができる。特に、１次粒子の平均
粒径が１μｍ以上４μｍ以下のリチウムニッケル複合酸
化物を製造するためには、水酸化物の１次粒子の平均粒
径を１μｍ〜４μｍの範囲となるように合成すればよ
い。また、水酸化ニッケル等を水に溶解した水溶液は、
反応性および収率を共に満足させるという観点から、そ
の濃度は０．５〜２Ｍとなるように調整することが望ま
しい。It should be noted that cobalt forms a solid solution with nickel.
It is desirable to use a cobalt composite compound. In particular, when using the above cobalt hydroxide and nickel hydroxide,
As a method for easily synthesizing a nickel-cobalt composite compound, for example, an aqueous solution obtained by dissolving nickel hydroxide and cobalt hydroxide in water is dropped into a strong alkali aqueous solution, and nickel-cobalt hydroxide (hereinafter, referred to as hydroxide) is used. .)
Can be used to coprecipitate and synthesize. According to this method, it is possible to control the particle diameter of particles serving as nuclei of the lithium-nickel composite oxide, so that it is possible to easily obtain a lithium-nickel composite oxide corresponding to the particle diameter of desired primary particles. . In particular, in order to produce a lithium-nickel composite oxide having an average primary particle size of 1 μm or more and 4 μm or less, it is necessary to synthesize the hydroxide such that the average primary particle size of the hydroxide is in the range of 1 μm to 4 μm. I just need. Also, an aqueous solution in which nickel hydroxide or the like is dissolved in water,
From the viewpoint of satisfying both the reactivity and the yield, the concentration is desirably adjusted to be 0.5 to 2M.
【００２７】強アルカリ水溶液としては、水酸化ナトリ
ウム水溶液、水酸化カリウム水溶液、アンモニア水等を
用いることができる。中でも、経済性を考慮すれば、水
酸化ナトリウム水溶液を用いることが望ましい。水酸化
ナトリウム水溶液を用いる場合には、１〜５Ｍ程度の濃
度のものを使用することが望ましい。As the strong alkaline aqueous solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, aqueous ammonia or the like can be used. Among them, it is preferable to use an aqueous solution of sodium hydroxide in consideration of economy. When using an aqueous sodium hydroxide solution, it is desirable to use a solution having a concentration of about 1 to 5M.
【００２８】上記反応を均一に行うために、水酸化ニッ
ケル等を水に溶解させた水溶液を強アルカリ水溶液に滴
下する際には攪拌して行うことが望ましい。攪拌速度、
強アルカリ水溶液のｐＨ値、反応温度等の条件は、合成
される水酸化物粒子の粒子径等に影響することから、所
望の粒子を得るために適宜設定すればよい。例えば、強
アルカリ水溶液のｐＨ値は、反応中略一定となるように
調整することが望ましく、その値は、１１〜１２とする
ことが望ましい。また、反応温度は、適度な反応速度を
得るため、２０〜４０℃とすることが望ましい。なお、
上記水酸化物は沈殿物として得られるため、これを濾
別、洗浄等して、他の化合物との混合に用いればよい。In order to carry out the above reaction uniformly, it is desirable to stir the aqueous solution obtained by dissolving nickel hydroxide or the like in water when dropping the solution into a strong alkaline aqueous solution. Stirring speed,
Conditions such as the pH value and the reaction temperature of the strong alkaline aqueous solution affect the particle size and the like of the hydroxide particles to be synthesized, and may be appropriately set to obtain desired particles. For example, the pH value of the strong alkaline aqueous solution is desirably adjusted so as to be substantially constant during the reaction, and the value is desirably 11 to 12. Further, the reaction temperature is desirably 20 to 40 ° C. in order to obtain an appropriate reaction rate. In addition,
Since the hydroxide is obtained as a precipitate, it may be filtered, washed, and used for mixing with another compound.
【００２９】上記各原料の混合は、通常の粉体の混合に
用いられている方法で行えばよい。具体的には、例え
ば、ボールミル、ミキサー、乳鉢等を用いて混合するこ
とができる。原料の混合割合は、製造しようとするリチ
ウムニッケル複合酸化物の組成に応じた割合とすればよ
い。The mixing of each of the above-mentioned raw materials may be carried out by a method used for mixing ordinary powders. Specifically, for example, mixing can be performed using a ball mill, a mixer, a mortar or the like. The mixing ratio of the raw materials may be a ratio according to the composition of the lithium nickel composite oxide to be produced.
【００３０】（２）焼成工程 本焼成工程は、原料混合工程で得られた混合物を酸素雰
囲気中で焼成してリチウムニッケル複合酸化物を得る工
程である。焼成温度は、７５０℃以上９５０℃以下とす
ることが望ましい。焼成温度が７５０℃未満であると、
反応が充分に進行せず、結晶性が低くなるからである。
反対に、９５０℃を超えると、リチウムがガス化し、反
応への寄与率が低くなるからである。なお、焼成時間は
焼成が完了するのに充分な時間であればよく、通常、１
２時間程度行えばよい。(2) Firing Step The firing step is a step of firing the mixture obtained in the raw material mixing step in an oxygen atmosphere to obtain a lithium nickel composite oxide. The firing temperature is desirably 750 ° C or more and 950 ° C or less. When the firing temperature is lower than 750 ° C,
This is because the reaction does not proceed sufficiently and the crystallinity becomes low.
Conversely, if the temperature exceeds 950 ° C., lithium gasifies and the contribution to the reaction decreases. The sintering time may be a time sufficient for completing the sintering.
It may be performed for about two hours.
【００３１】〈リチウム二次電池〉本発明のリチウムニ
ッケル複合酸化物を正極活物質として使用して、リチウ
ム二次電池を構成することができる。以下、そのリチウ
ム二次電池の主要構成について説明する。一般にリチウ
ム二次電池は、リチウムイオンを吸蔵・放出する正極お
よび負極と、この正極と負極との間に挟装されるセパレ
ータと、正極と負極の間をリチウムイオンを移動させる
非水電解液とから構成される。本実施形態の二次電池も
この構成に従うため、以下の説明は、これらの構成要素
のそれぞれについて行うこととする。<Lithium Secondary Battery> A lithium secondary battery can be constructed using the lithium nickel composite oxide of the present invention as a positive electrode active material. Hereinafter, the main configuration of the lithium secondary battery will be described. Generally, a lithium secondary battery includes a positive electrode and a negative electrode that occlude and release lithium ions, a separator that is interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte that moves lithium ions between the positive electrode and the negative electrode. Consists of Since the secondary battery of the present embodiment also follows this configuration, the following description will be made for each of these components.
【００３２】正極は、上述したように、リチウムイオン
を吸蔵・放出できる正極活物質に導電材および結着剤を
混合し、必要に応じ適当な溶媒を加えて、ペースト状の
正極合材としたものを、アルミニウム等の金属箔製の集
電体表面に塗布、乾燥し、その後プレスによって活物質
密度を高めることによって形成することができる。As described above, the positive electrode was prepared by mixing a conductive material and a binder with a positive electrode active material capable of occluding and releasing lithium ions, and adding an appropriate solvent if necessary, to form a paste-like positive electrode mixture. The active material can be formed by applying the material on the surface of a current collector made of a metal foil such as aluminum, drying the material, and then increasing the active material density by pressing.
【００３３】本実施形態においては、上記本発明のリチ
ウムニッケル複合酸化物を正極活物質とする。なお、リ
チウムニッケル複合酸化物うち１種類のものを正極活物
質として用いることも、また、２種類以上のものを混合
して用いることもできる。In this embodiment, the lithium nickel composite oxide of the present invention is used as a positive electrode active material. Note that one of the lithium-nickel composite oxides can be used as the positive electrode active material, or two or more can be used as a mixture.
【００３４】正極に用いる導電材は、正極活物質層の電
気伝導性を確保するためのものであり、カーボンブラッ
ク、アセチレンブラック、黒鉛等の炭素物質の１種また
は２種以上を混合したものを用いることができる。結着
剤は、活物質粒子を繋ぎ止める役割を果たすもので、ポ
リテトラフルオロエチレン、ポリフッ化ビニリデン、フ
ッ素ゴム等の含フッ素樹脂、ポリプロピレン、ポリエチ
レン等の熱可塑性樹脂を用いることができる。これら活
物質、導電材、結着剤を分散させる溶剤としては、Ｎ−
メチル−２−ピロリドン等の有機溶剤を用いることがで
きる。The conductive material used for the positive electrode is for ensuring the electrical conductivity of the positive electrode active material layer, and may be a mixture of one or more carbon materials such as carbon black, acetylene black, and graphite. Can be used. The binder plays a role of binding the active material particles, and a fluororesin such as polytetrafluoroethylene, polyvinylidene fluoride, or fluororubber, or a thermoplastic resin such as polypropylene or polyethylene can be used. As a solvent for dispersing these active material, conductive material and binder, N-
An organic solvent such as methyl-2-pyrrolidone can be used.
【００３５】負極は、負極活物質である金属リチウム
を、一般の電池のそれと同様に、シート状にして、ある
いはシート状にしたものをニッケル、ステンレス等の集
電体網に圧着して形成することができる。負極活物質に
は金属リチウムに代え、リチウム合金、またはリチウム
化合物をも用いることができる。The negative electrode is formed by sheeting metallic lithium, which is the negative electrode active material, in the same manner as that of a general battery, or by pressing the sheet-like material onto a current collector network of nickel, stainless steel, or the like. be able to. As the negative electrode active material, a lithium alloy or a lithium compound can be used instead of metal lithium.
【００３６】また負極のもう一つの形態として、負極活
物質にリチウムイオンを吸蔵・脱離できる炭素物質を用
いて負極を構成させることもできる。使用できる炭素物
質としては、天然黒鉛、球状あるいは繊維状の人造黒
鉛、コークス等の易黒鉛化性炭素、フェノール樹脂焼成
体等の難黒鉛化性炭素等を挙げることができ、これらの
１種を単独であるいは２種以上を混合して用いることが
できる。この場合は、負極活物質に結着剤を混合し、適
当な溶媒を加えてペースト状にした負極合材を、銅等の
金属箔集電体の表面に塗布乾燥して形成することができ
る。As another form of the negative electrode, the negative electrode can be constituted by using a carbon material capable of inserting and extracting lithium ions as the negative electrode active material. Examples of the carbon material that can be used include natural graphite, spherical or fibrous artificial graphite, easily graphitizable carbon such as coke, and non-graphitizable carbon such as a phenol resin fired body. They can be used alone or in combination of two or more. In this case, the negative electrode active material can be formed by mixing a binder with the negative electrode active material, adding a suitable solvent to form a paste, and applying and drying the negative electrode mixture on the surface of a metal foil current collector such as copper. .
【００３７】炭素物質を負極活物質とした場合、正極同
様、負極結着剤としてはポリフッ化ビニリデン等の含フ
ッ素樹脂等を、溶剤としてはＮ−メチル−２−ピロリド
ン等の有機溶剤を用いることができる。When the carbon material is used as the negative electrode active material, a fluorine-containing resin such as polyvinylidene fluoride or the like is used as the negative electrode binder and an organic solvent such as N-methyl-2-pyrrolidone is used as the solvent, similarly to the positive electrode. Can be.
【００３８】正極と負極の間に挟装されるセパレータ
は、正極と負極とを隔離しつつ電解液を保持してイオン
を通過させるものであり、ポリエチレン、ポリプロピレ
ン等の薄い微多孔膜を用いることができる。The separator sandwiched between the positive electrode and the negative electrode separates the positive electrode from the negative electrode, holds the electrolytic solution and allows ions to pass therethrough, and uses a thin microporous membrane such as polyethylene or polypropylene. Can be.
【００３９】非水電解液は、有機溶媒に電解質を溶解さ
せたもので、有機溶媒としては、非プロトン性有機溶
媒、例えばエチレンカーボネート、プロピレンカーボネ
ート、ジメチルカーボネート、ジエチルカーボネート、
γブチロラクトン、アセトニトリル、ジメトキシエタ
ン、テトラヒドロフラン、ジオキソラン、塩化メチレン
等の１種またはこれらの２種以上の混合液を用いること
ができる。また、溶解させる電解質としては、溶解させ
ることによりリチウムイオンを生じるＬｉＩ、ＬｉＣｌ
Ｏ4、ＬｉＡｓＦ6、ＬｉＢＦ4、ＬｉＰＦ6等を用いるこ
とができる。The non-aqueous electrolyte is obtained by dissolving an electrolyte in an organic solvent. Examples of the organic solvent include aprotic organic solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and the like.
One kind of γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran, dioxolane, methylene chloride and the like, or a mixture of two or more kinds thereof can be used. As the electrolyte to be dissolved, LiI, LiCl which generates lithium ions when dissolved are used.
O 4 , LiAsF 6 , LiBF 4 , LiPF 6 and the like can be used.
【００４０】なお、上記セパレータおよび非水電解液と
いう構成に代えて、ポリエチレンオキシド等の高分子量
ポリマーとＬｉＣｌＯ4やＬｉＮ（ＣＦ3ＳＯ2）2等のリ
チウム塩を使用した高分子固体電解質を用いることもで
き、また、上記非水電解液をポリアクリロニトリル等の
固体高分子マトリクスにトラップさせたゲル電解質を用
いることもできる。In place of the above-described structure of the separator and the non-aqueous electrolyte, a polymer solid electrolyte using a high molecular weight polymer such as polyethylene oxide and a lithium salt such as LiClO 4 or LiN (CF 3 SO 2 ) 2 is used. It is also possible to use a gel electrolyte in which the above non-aqueous electrolyte is trapped in a solid polymer matrix such as polyacrylonitrile.
【００４１】以上のものから構成されるリチウム二次電
池であるが、その形状はコイン型、積層型、円筒型等の
種々のものとすることができる。いずれの形状を採る場
合であっても、正極および負極にセパレータを挟装させ
電極体とし、正極および負極から外部に通ずる正極端子
および負極端子までの間をそれぞれ導通させるようにし
て、この電極体を非水電解液とともに電池ケースに密閉
して電池を完成させることができる。The lithium secondary battery constituted as described above can be formed in various shapes such as a coin type, a stacked type and a cylindrical type. In any case, the separator is sandwiched between the positive electrode and the negative electrode to form an electrode body, and conduction is provided between the positive electrode and the negative electrode to the positive electrode terminal and the negative electrode terminal that communicate with the outside. Can be sealed in a battery case together with the non-aqueous electrolyte to complete the battery.
【００４２】〈他の実施形態の許容〉これまでに説明し
た本発明のリチウムニッケル複合酸化物、リチウム二次
電池の実施形態は例示にすぎず、本発明のリチウムニッ
ケル複合酸化物、また本発明のリチウムニッケル複合酸
化物を正極活物質に用いたリチウム二次電池は、上記実
施形態を始めとして、当業者の知識に基づいて種々の変
更、改良を施した形態で実施することができる。<Allowance of Other Embodiments> The embodiments of the lithium-nickel composite oxide and the lithium secondary battery of the present invention described above are merely examples, and the lithium-nickel composite oxide of the present invention and the present invention The lithium secondary battery using the lithium-nickel composite oxide as the positive electrode active material can be implemented with various modifications and improvements based on the knowledge of those skilled in the art, including the above embodiment.
【００４３】[0043]
【実施例】上記実施形態に基づいて、１次粒子の平均粒
径、組成におけるＣｏ、Ａｌの置換割合が異なるリチウ
ムニッケル複合酸化物を種々製造した。そして、それら
のリチウムニッケル複合酸化物を正極活物質として用い
たリチウム二次電池を作製し、高温保存試験を行うこと
により電池の保存特性を評価した。以下、説明する。EXAMPLES Based on the above embodiment, various lithium nickel composite oxides having different average particle diameters of primary particles and substitution ratios of Co and Al in the composition were produced. Then, lithium secondary batteries using these lithium-nickel composite oxides as positive electrode active materials were produced, and storage characteristics of the batteries were evaluated by performing a high-temperature storage test. This will be described below.
【００４４】〈Ｃｏ、Ａｌの置換割合と電池の容量およ
び内部抵抗増加率との関係〉 （ａ）製造したリチウムニッケル複合酸化物 正極活物質として用いるリチウムニッケル複合酸化物に
おいて、Ｃｏ、Ａｌの置換割合と電池の容量および内部
抵抗増加率との関係を調べるために、Ｃｏ、Ａｌの置換
割合の異なる種々のリチウムニッケル複合酸化物を製造
した。具体的には、Ａｌの置換割合を５モル％とし（以
下、Ａｌ、Ｃｏの置換割合において％はモル％を意味す
る）、Ｃｏの置換割合を１５、２０、３０、および４０
％としたもの、Ａｌの置換割合を１０％とし、Ｃｏの置
換割合を１５、２０、および３０％としたものの計７種
のリチウムニッケル複合酸化物を製造した。なお、リチ
ウムニッケル複合酸化物の１次粒子の平均粒径は１μｍ
とした。<Relationship Between Co and Al Substitution Ratio and Capacity and Internal Resistance Increase Rate of Battery> (a) Lithium Nickel Composite Oxide Manufactured In the lithium nickel composite oxide used as the positive electrode active material, substitution of Co and Al was performed. Various lithium nickel composite oxides having different substitution ratios of Co and Al were manufactured in order to examine the relationship between the ratio and the capacity of the battery and the increase rate of the internal resistance. Specifically, the substitution ratio of Al is set to 5 mol% (hereinafter, “%” means mol% in the substitution ratio of Al and Co), and the substitution ratios of Co are 15, 20, 30, and 40.
%, The substitution ratio of Al was 10%, and the substitution ratio of Co was 15, 20, and 30%, thereby producing a total of seven types of lithium nickel composite oxides. The average particle size of the primary particles of the lithium nickel composite oxide is 1 μm
And
【００４５】リチウム源としてＬｉＯＨ・Ｈ2Ｏを、ニ
ッケル、コバルト、アルミニウム源としてＮｉ（ＯＨ）
2、Ｃｏ（ＯＨ）2、Ａｌ（ＯＨ）3をそれぞれ製造しよ
うとするリチウムニッケル複合酸化物の組成となるよう
に混合した。なお、予め、２ＭのＮｉ（ＯＨ）2および
Ｃｏ（ＯＨ）2の各水溶液を混合し、この水溶液を水酸
化ナトリウム水溶液に滴下し、水酸化物粒子を析出合成
しておいた。反応温度は３０℃、反応中のｐＨ値は、１
１〜１２であった。析出した水酸化物粒子を濾別、洗浄
した後、ＬｉＯＨ・Ｈ2Ｏ、Ａｌ（ＯＨ）3と混合した。
なお、水酸化物の１次粒子の平均粒径は、２μｍとし
た。そして、上記混合物を、酸素気流中、８５０℃で１
２時間焼成してリチウムニッケル複合酸化物を得た。LiOH.H 2 O as a lithium source, nickel and cobalt, and Ni (OH) as an aluminum source
2 , Co (OH) 2 , and Al (OH) 3 were mixed so as to have the composition of the lithium nickel composite oxide to be produced. In addition, each aqueous solution of 2M Ni (OH) 2 and Co (OH) 2 was previously mixed, and this aqueous solution was dropped into an aqueous sodium hydroxide solution to precipitate and synthesize hydroxide particles. The reaction temperature was 30 ° C and the pH value during the reaction was 1
1-12. The precipitated hydroxide particles were separated by filtration, washed, and then mixed with LiOH · H 2 O and Al (OH) 3 .
The average primary particle size of the hydroxide was 2 μm. Then, the mixture is heated at 850 ° C. for 1 hour in an oxygen stream.
By firing for 2 hours, a lithium nickel composite oxide was obtained.
【００４６】Ａｌの置換割合が５％であってＣｏの置換
割合が小さいものから順に、＃０１、０２、０３、０４
と、また、Ａｌの置換割合が１０％であってＣｏの置換
割合が小さいものから順に、＃０５、０６、０７と番号
付けした。なお、＃０１、＃０２、＃０５、および＃０
６のリチウムニッケル複合酸化物が本発明のリチウムニ
ッケル複合酸化物に相当するものである。# 01, 02, 03, 04 in order from the one where the substitution ratio of Al is 5% and the substitution ratio of Co is small.
And # 05, 06, and 07 in order from the one with the Al substitution ratio of 10% and the Co substitution ratio being small. Note that # 01, # 02, # 05, and # 0
The lithium-nickel composite oxide of No. 6 corresponds to the lithium-nickel composite oxide of the present invention.
【００４７】（ｂ）リチウム二次電池 上記７種のリチウムニッケル複合酸化物をそれぞれ正極
活物質に用いてリチウム二次電池を作製した。正極は、
まず、正極活物質となるそれぞれのリチウムニッケル複
合酸化物８５重量部に、導電材としてのカーボンブラッ
クを１０重量部、結着剤としてのポリフッ化ビニリデン
を５重量部混合し、溶剤として適量のＮ−メチル−２−
ピロリドンを添加して、ペースト状の正極合材を調製
し、次いで、このペースト状の正極合材を厚さ２０μｍ
のアルミニウム箔集電体の両面に塗布し、乾燥させ、そ
の後ロールプレスにて圧縮し、正極合材の厚さが片面当
たり４０μｍのシート状のものを作製した。このシート
状の正極は５４ｍｍ×４５０ｍｍの大きさに裁断して用
いた。(B) Lithium secondary battery A lithium secondary battery was manufactured using each of the above seven lithium nickel composite oxides as a positive electrode active material. The positive electrode is
First, 10 parts by weight of carbon black as a conductive material and 5 parts by weight of polyvinylidene fluoride as a binder were mixed with 85 parts by weight of each lithium nickel composite oxide serving as a positive electrode active material, and an appropriate amount of N was used as a solvent. -Methyl-2-
Pyrrolidone was added to prepare a paste-like positive electrode mixture, and then this paste-like positive electrode mixture was 20 μm thick.
Was coated on both sides of an aluminum foil current collector, dried, and then compressed by a roll press to produce a sheet-shaped positive electrode mixture having a thickness of 40 μm per side. This sheet-shaped positive electrode was cut into a size of 54 mm × 450 mm for use.
【００４８】対向させる負極は、黒鉛化メソカーボンマ
イクロビーズ（黒鉛化ＭＣＭＢ）を活物質として用い
た。まず、負極活物質となる黒鉛化ＭＣＭＢの９５重量
部に、結着剤としてのポリフッ化ビニリデンを５重量部
混合し、溶剤として適量のＮ−メチル−２−ピロリドン
を添加し、ペースト状の負極合材を調製し、次いで、こ
のペースト状の負極合材を厚さ１０μｍの銅箔集電体の
両面に塗布し、乾燥させ、その後ロールプレスにて圧縮
し、負極合材の厚さが片面当たり３０μｍのシート状の
ものを作製した。このシート状の負極は５６ｍｍ×５０
０ｍｍの大きさに裁断して用いた。As a negative electrode to be opposed, graphitized mesocarbon microbeads (graphitized MCMB) were used as an active material. First, 95 parts by weight of graphitized MCMB as a negative electrode active material, 5 parts by weight of polyvinylidene fluoride as a binder were mixed, and an appropriate amount of N-methyl-2-pyrrolidone was added as a solvent, and a paste-like negative electrode was added. A mixture was prepared, and then this paste-like negative electrode mixture was applied to both sides of a copper foil current collector having a thickness of 10 μm, dried, and then compressed by a roll press. A sheet having a thickness of 30 μm was prepared. This sheet-shaped negative electrode is 56 mm x 50
It was cut into a size of 0 mm and used.
【００４９】上記それぞれ正極および負極を、それらの
間に厚さ２５μｍ、幅５８ｍｍのポリエチレン製セパレ
ータを挟んで捲回し、ロール状の電極体を形成した。そ
して、その電極体を１８６５０型円筒形電池ケース（外
径１８ｍｍφ、長さ６５ｍｍ）に挿設し、非水電解液を
注入し、その電池ケースを密閉して円筒型リチウム二次
電池を作製した。なお、非水電解液は、エチレンカーボ
ネートとジエチルカーボネートとを体積比で１：１に混
合した混合溶媒に、ＬｉＰＦ6を１Ｍの濃度で溶解した
ものを用いた。The positive electrode and the negative electrode were wound with a polyethylene separator having a thickness of 25 μm and a width of 58 mm interposed therebetween to form a roll-shaped electrode body. Then, the electrode body was inserted into a 18650-type cylindrical battery case (outside diameter 18 mmφ, length 65 mm), a non-aqueous electrolyte was injected, and the battery case was sealed to produce a cylindrical lithium secondary battery. . As the non-aqueous electrolyte, a solution obtained by dissolving LiPF 6 at a concentration of 1 M in a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used.
【００５０】なお、上記＃０１〜＃０７のリチウムニッ
ケル複合酸化物を正極活物質に用いたリチウム二次電池
をそれぞれ＃０１〜＃０７のリチウム二次電池とした。The lithium secondary batteries using the lithium nickel composite oxides # 01 to # 07 as the positive electrode active material were referred to as lithium secondary batteries # 01 to # 07, respectively.
【００５１】（ｃ）リチウム二次電池の保存特性の評価 上記＃０１〜＃０７のそれぞれのリチウム二次電池につ
いて保存特性を評価した。まず、コンディショニングと
して、温度２０℃下にて、電流密度０．２ｍＡ／ｃｍ2
の定電流で４．１Ｖまで充電した後、電流密度０．２ｍ
Ａ／ｃｍ2の定電流で３．０Ｖまで放電を行った。コン
ディショニングの後、初期容量を測定するために、温度
２０℃下にて、３サイクルの充放電を行った。その充放
電条件は、電流密度０．１ｍＡ／ｃｍ2の定電流で充電
上限電圧４．１Ｖまで充電を行い、さらに４．１Ｖの定
電圧で２時間充電を続け、その後、電流密度０．１ｍＡ
／ｃｍ2の定電流で放電下限電圧３．０Ｖまで放電を行
う充放電を１サイクルとするものである。この充放電の
３サイクル目の放電容量を、２０℃における初期容量と
した。(C) Evaluation of storage characteristics of lithium secondary battery The storage characteristics of each of the lithium secondary batteries # 01 to # 07 were evaluated. First, as conditioning, at a temperature of 20 ° C., a current density of 0.2 mA / cm 2
After charging to 4.1 V at a constant current of 0.2 m, the current density was 0.2 m
Discharge was performed to 3.0 V at a constant current of A / cm 2 . After the conditioning, three cycles of charge and discharge were performed at a temperature of 20 ° C. to measure the initial capacity. The charging and discharging conditions are as follows: charging is performed at a constant current of a current density of 0.1 mA / cm 2 up to a charging upper limit voltage of 4.1 V, and charging is further continued at a constant voltage of 4.1 V for 2 hours.
The charge / discharge in which discharge is performed at a constant current of / cm 2 to a discharge lower limit voltage of 3.0 V is defined as one cycle. The discharge capacity at the third cycle of this charge / discharge was defined as the initial capacity at 20 ° C.
【００５２】次いで、初期の内部抵抗を算出するため
に、入出力パワー測定を行い、入出力時の内部抵抗を算
出した。入出力パワー測定は以下の条件で行った。ま
ず、各リチウム二次電池の初期容量の５０％まで充電し
た状態（ＳＯＣ５０％）で、１Ａの電流で１０秒間放電
させ、１０秒目の電圧を測定した。再びＳＯＣ５０％の
状態に充電した後、３Ａの電流で１０秒間放電させ、１
０秒目の電圧を測定した。さらに、ＳＯＣ５０％の状態
に充電した後、５Ａの電流で１０秒間放電させ、１０秒
目の電圧を測定した。そして、電圧の電流依存性を求
め、電流−電圧直線の勾配を出力時の内部抵抗とした。
また、同様の手順で充電を行い、各１０秒目の電圧を測
定して、電流−電圧直線の勾配から入力時の内部抵抗を
求めた。求めた入出力時の内部抵抗の平均値を初期内部
抵抗とした。Next, in order to calculate the initial internal resistance, the input / output power was measured, and the internal resistance at the time of input / output was calculated. The input / output power measurement was performed under the following conditions. First, in a state where each lithium secondary battery was charged to 50% of the initial capacity (SOC 50%), the battery was discharged at a current of 1 A for 10 seconds, and the voltage at the 10th second was measured. After being charged again to the state of SOC 50%, the battery was discharged at a current of 3 A for 10 seconds, and
The voltage at 0 seconds was measured. Further, after the battery was charged to the state of 50% SOC, the battery was discharged at a current of 5 A for 10 seconds, and the voltage at the 10th second was measured. Then, the current dependence of the voltage was determined, and the gradient of the current-voltage straight line was defined as the internal resistance at the time of output.
In addition, charging was performed in the same manner, the voltage at each 10 seconds was measured, and the internal resistance at the time of input was obtained from the gradient of the current-voltage straight line. The average value of the obtained internal resistance at the time of input and output was defined as the initial internal resistance.
【００５３】次に、保存試験を行った。保存試験は、電
流密度０．２ｍＡ／ｃｍ2の定電流で電圧が４．１Ｖに
到達するまで充電を行った後、さらに４．１Ｖの定電圧
で充電を続け、合計７時間の充電を行うことにより、各
二次電池をＳＯＣ１００％の状態とした後、６０℃の恒
温槽に１ヶ月間保存することとした。保存後に、上記と
同様にして入出力時の内部抵抗を求め、その平均値を保
存後内部抵抗とした。そして、保存試験の前後における
内部抵抗の値から、式［｛（保存後内部抵抗／初期内部
抵抗）−１｝×１００］を用いて内部抵抗増加率を計算
した。Next, a storage test was performed. In the storage test, after charging was performed at a constant current of 0.2 mA / cm 2 until the voltage reached 4.1 V, charging was further continued at a constant voltage of 4.1 V, and charging was performed for a total of 7 hours. As a result, each of the secondary batteries was kept in a constant temperature bath at 60 ° C. for one month after the state of the SOC was set to 100%. After storage, the internal resistance during input / output was determined in the same manner as above, and the average value was taken as the internal resistance after storage. Then, from the values of the internal resistance before and after the storage test, the internal resistance increase rate was calculated using the formula [{(internal resistance after storage / initial internal resistance) −1} × 100].
【００５４】＃０１〜＃０７の二次電池について、初期
容量と内部抵抗増加率との関係を図１に示す。図１か
ら、１次粒子の平均粒径が同じ場合に、Ｃｏの置換割合
が大きいリチウムニッケル複合酸化物を用いた二次電池
ほど初期容量は小さくなることがわかる。さらに、Ａｌ
の置換割合が大きいリチウムニッケル複合酸化物を用い
た二次電池ほど内部抵抗の増加は小さくなることがわか
る。したがって、実用的な二次電池の容量として１４０
ｍＡｈ／ｇ以上が必要となることを考慮すると、Ｃｏの
置換割合が１０〜２０％、かつＡｌの置換割合が５〜１
０％である本発明のリチウムニッケル複合酸化物を用い
た二次電池（＃０１、＃０２、＃０５、および＃０６）
は、容量が大きく、かつ内部抵抗の増加が小さいことが
確認できた。FIG. 1 shows the relationship between the initial capacity and the rate of increase in the internal resistance of the secondary batteries # 01 to # 07. From FIG. 1, it can be seen that, when the average particle size of the primary particles is the same, the initial capacity becomes smaller as the secondary battery using the lithium-nickel composite oxide having a higher Co substitution ratio becomes smaller. Furthermore, Al
It can be seen that a secondary battery using a lithium-nickel composite oxide having a larger percentage of substitution has a smaller increase in internal resistance. Therefore, a practical secondary battery capacity of 140
Considering that mAh / g or more is required, the substitution ratio of Co is 10 to 20% and the substitution ratio of Al is 5 to 1%.
Secondary battery using lithium nickel composite oxide of 0% of the present invention (# 01, # 02, # 05, and # 06)
Was confirmed to have a large capacity and a small increase in internal resistance.
【００５５】〈Ｃｏ、Ａｌの置換割合および１次粒子の
粒子径と容量残存率との関係〉 （ａ）製造したリチウムニッケル複合酸化物 （１）第１シリーズのリチウムニッケル複合酸化物 組成式ＬｉＮｉ0.85Ｃｏ0.1Ａｌ0.05Ｏ2で表される規則
配列層状岩塩構造のリチウムニッケル複合酸化物であっ
て、その１次粒子の平均粒径が、０．２μｍ、１μｍ、
４μｍ、５μｍと異なる４種のものを製造した。<Relationship between Co and Al substitution ratios and particle diameters of primary particles and residual capacity ratio> (a) Lithium nickel composite oxide produced (1) Lithium nickel composite oxide of the first series Composition formula LiNi A lithium-nickel composite oxide having an ordered layered rock salt structure represented by 0.85 Co 0.1 Al 0.05 O 2 , wherein the primary particles have an average particle size of 0.2 μm, 1 μm,
Four types different from 4 μm and 5 μm were produced.
【００５６】上記＃０１〜＃０７のリチウムニッケル複
合酸化物の製造において、原料となる各化合物の混合割
合を、Ｌｉ、Ｎｉ、Ｃｏ、Ａｌがモル比で１：０．８
５：０．１：０．０５とした以外は、＃０１〜＃０７の
リチウムニッケル複合酸化物と同様に製造した。なお、
水酸化物の１次粒子の平均粒径は、製造しようとするリ
チウムニッケル複合酸化物の１次粒子の粒子径を考慮し
て適宜調製した。In the production of the lithium-nickel composite oxides of # 01 to # 07, the mixing ratio of each compound as a raw material is such that Li, Ni, Co, and Al are mixed in a molar ratio of 1: 0.8.
Except that the ratio was 5: 0.1: 0.05, it was produced in the same manner as the lithium-nickel composite oxides of # 01 to # 07. In addition,
The average particle size of the primary particles of the hydroxide was appropriately adjusted in consideration of the particle size of the primary particles of the lithium nickel composite oxide to be produced.
【００５７】本リチウムニッケル複合酸化物を第１シリ
ーズのリチウムニッケル複合酸化物とし、１次粒子の平
均粒径が０．２μｍ、１μｍ、４μｍ、５μｍの順に＃
１１、＃１２、＃１３、＃１４と番号付けした。This lithium nickel composite oxide is referred to as a first series lithium nickel composite oxide, and the primary particles have an average particle size of 0.2 μm, 1 μm, 4 μm, and 5 μm in this order.
11, # 12, # 13, and # 14.
【００５８】（２）第２シリーズのリチウムニッケル複
合酸化物 組成式ＬｉＮｉ0.7Ｃｏ0.2Ａｌ0.1Ｏ2で表される規則配
列層状岩塩構造のリチウムニッケル複合酸化物であっ
て、第１シリーズと同様、その１次粒子の平均粒径が異
なるものを４種製造した。＃０１〜＃０７のリチウムニ
ッケル複合酸化物の製造において、原料となる各化合物
の混合割合を、Ｌｉ、Ｎｉ、Ｃｏ、Ａｌがモル比で１：
０．７：０．２：０．１と変更した以外は、＃０１〜＃
０７のリチウムニッケル複合酸化物と同様に製造した。(2) Lithium-nickel composite oxide of the second series This is a lithium-nickel composite oxide having an ordered layered rock salt structure represented by the composition formula LiNi 0.7 Co 0.2 Al 0.1 O 2 , similar to the first series. Four types of primary particles having different average particle sizes were produced. In the production of the lithium-nickel composite oxides of # 01 to # 07, the mixing ratio of each compound as a raw material was such that Li, Ni, Co, and Al were mixed at a molar ratio of 1:
# 01 to #, except for changing to 0.7: 0.2: 0.1
07 lithium nickel composite oxide.
【００５９】本リチウムニッケル複合酸化物を第２シリ
ーズのリチウムニッケル複合酸化物とし、１次粒子の平
均粒径が０．２μｍ、１μｍ、４μｍ、５μｍの順に＃
２１、＃２２、＃２３、＃２４と番号付けした。This lithium nickel composite oxide is referred to as a second series of lithium nickel composite oxide, and the average particle size of the primary particles is 0.2 μm, 1 μm, 4 μm, and 5 μm in this order.
21, # 22, # 23, and # 24.
【００６０】（３）第３シリーズのリチウムニッケル複
合酸化物 組成式ＬｉＮｉ0.83Ｃｏ0.15Ａｌ0.02Ｏ2で表される規
則配列層状岩塩構造のリチウムニッケル複合酸化物であ
って、その１次粒子の平均粒径が異なるものを４種製造
した。＃０１〜＃０７のリチウムニッケル複合酸化物の
製造において、原料となる各化合物の混合割合を、Ｌ
ｉ、Ｎｉ、Ｃｏ、Ａｌがモル比で１：０．８３：０．１
５：０．０２と変更した以外は、＃０１〜＃０７のリチ
ウムニッケル複合酸化物と同様に製造した。(3) Lithium-nickel composite oxide of the third series This is a lithium-nickel composite oxide having an ordered layered rock salt structure represented by a composition formula: LiNi 0.83 Co 0.15 Al 0.02 O 2 , wherein the average of primary particles is Four types having different particle sizes were produced. In the production of the lithium nickel composite oxides of # 01 to # 07, the mixing ratio of each compound as a raw material is represented by L
i, Ni, Co, Al in molar ratio of 1: 0.83: 0.1
Except having changed to 5: 0.02, it manufactured similarly to the lithium nickel composite oxide of # 01- # 07.
【００６１】本リチウムニッケル複合酸化物を第３シリ
ーズのリチウムニッケル複合酸化物とし、１次粒子の平
均粒径が０．２μｍ、１μｍ、４μｍ、５μｍの順に＃
３１、＃３２、＃３３、＃３４と番号付けした。The lithium-nickel composite oxide is referred to as a third series of lithium-nickel composite oxides. The primary particles have an average particle size of 0.2 μm, 1 μm, 4 μm, and 5 μm in this order.
31, # 32, # 33, and # 34.
【００６２】（４）第４シリーズのリチウムニッケル複
合酸化物 組成式ＬｉＮｉ0.65Ｃｏ0.15Ａｌ0.2Ｏ2で表される規則
配列層状岩塩構造のリチウムニッケル複合酸化物であっ
て、その１次粒子の平均粒径が異なるものを４種製造し
た。＃０１〜＃０７のリチウムニッケル複合酸化物の製
造において、原料となる各化合物の混合割合を、Ｌｉ、
Ｎｉ、Ｃｏ、Ａｌがモル比で１：０．６５：０．１５：
０．２と変更した以外は、＃０１〜＃０７のリチウムニ
ッケル複合酸化物と同様に製造した。(4) Lithium-nickel composite oxide of the fourth series This is a lithium-nickel composite oxide having an ordered layered rock-salt structure represented by the composition formula LiNi 0.65 Co 0.15 Al 0.2 O 2 , wherein the average of primary particles thereof is Four types having different particle sizes were produced. In the production of the lithium nickel composite oxides of # 01 to # 07, the mixing ratio of each compound as a raw material was changed to Li,
Ni, Co, Al in molar ratio of 1: 0.65: 0.15:
Except having changed to 0.2, it manufactured similarly to the lithium nickel composite oxide of # 01- # 07.
【００６３】本リチウムニッケル複合酸化物を第４シリ
ーズのリチウムニッケル複合酸化物とし、１次粒子の平
均粒径が０．２μｍ、１μｍ、４μｍ、５μｍの順に＃
４１、＃４２、＃４３、＃４４と番号付けした。The lithium-nickel composite oxide is referred to as a fourth series of lithium-nickel composite oxides. The average primary particle diameter is 0.2 μm, 1 μm, 4 μm, and 5 μm in this order.
41, # 42, # 43, and # 44.
【００６４】（５）第５シリーズのリチウムニッケル複
合酸化物 組成式ＬｉＮｉ0.9Ｃｏ0.05Ａｌ0.05Ｏ2で表される規則
配列層状岩塩構造のリチウムニッケル複合酸化物であっ
て、その１次粒子の平均粒径が異なるものを４種製造し
た。＃０１〜＃０７のリチウムニッケル複合酸化物の製
造において、原料となる各化合物の混合割合を、Ｌｉ、
Ｎｉ、Ｃｏ、Ａｌがモル比で１：０．９：０．０５：
０．０５と変更した以外は、＃０１〜＃０７のリチウム
ニッケル複合酸化物と同様に製造した。(5) Fifth series lithium-nickel composite oxide This is a lithium-nickel composite oxide having an ordered layered rock salt structure represented by a composition formula: LiNi 0.9 Co 0.05 Al 0.05 O 2 , wherein the average of primary particles is Four types having different particle sizes were produced. In the production of the lithium nickel composite oxides of # 01 to # 07, the mixing ratio of each compound as a raw material was changed to Li,
Ni, Co, Al in molar ratio of 1: 0.9: 0.05:
Except having changed to 0.05, it manufactured similarly to the lithium nickel composite oxide of # 01- # 07.
【００６５】本リチウムニッケル複合酸化物を第５シリ
ーズのリチウムニッケル複合酸化物とし、１次粒子の平
均粒径が０．２μｍ、１μｍ、４μｍ、５μｍの順に＃
５１、＃５２、＃５３、＃５４と番号付けした。This lithium nickel composite oxide is referred to as a fifth series lithium nickel composite oxide, and the average primary particle size is 0.2 μm, 1 μm, 4 μm, and 5 μm in this order.
51, # 52, # 53, and # 54.
【００６６】（６）第６シリーズのリチウムニッケル複
合酸化物 組成式ＬｉＮｉ0.7Ｃｏ0.25Ａｌ0.05Ｏ2で表される規則
配列層状岩塩構造のリチウムニッケル複合酸化物であっ
て、その１次粒子の平均粒径が異なるものを４種製造し
た。＃０１〜＃０７のリチウムニッケル複合酸化物の製
造において、原料となる各化合物の混合割合を、Ｌｉ、
Ｎｉ、Ｃｏ、Ａｌがモル比で１：０．７：０．２５：
０．０５と変更した以外は、＃０１〜＃０７のリチウム
ニッケル複合酸化物と同様に製造した。(6) Lithium-nickel composite oxide of the sixth series This is a lithium-nickel composite oxide having an ordered layered rock salt structure represented by a composition formula: LiNi 0.7 Co 0.25 Al 0.05 O 2 , wherein the average of primary particles is Four types having different particle sizes were produced. In the production of the lithium nickel composite oxides of # 01 to # 07, the mixing ratio of each compound as a raw material was changed to Li,
Ni, Co, Al in molar ratio of 1: 0.7: 0.25:
Except having changed to 0.05, it manufactured similarly to the lithium nickel composite oxide of # 01- # 07.
【００６７】本リチウムニッケル複合酸化物を第６シリ
ーズのリチウムニッケル複合酸化物とし、１次粒子の平
均粒径が０．２μｍ、１μｍ、４μｍ、５μｍの順に＃
６１、＃６２、＃６３、＃６４と番号付けした。This lithium nickel composite oxide is referred to as a sixth series of lithium nickel composite oxide, and the primary particles have an average particle size of 0.2 μm, 1 μm, 4 μm, and 5 μm in this order.
61, # 62, # 63, and # 64.
【００６８】上記第１〜６シリーズの各リチウムニッケ
ル複合酸化物について、その組成および１次粒子の平均
粒径を表１にまとめて示す。なお、＃１２、＃１３、＃
２２、および＃２３のリチウムニッケル複合酸化物が本
発明のリチウムニッケル複合酸化物に相当するものであ
る。Table 1 shows the compositions and the average primary particle diameters of the lithium nickel composite oxides of the first to sixth series. Note that # 12, # 13, #
The lithium nickel composite oxides Nos. 22 and # 23 correspond to the lithium nickel composite oxide of the present invention.
【００６９】[0069]
【表１】 [Table 1]
【００７０】（ｂ）リチウム二次電池 第１〜６シリーズのリチウムニッケル複合酸化物をそれ
ぞれ正極活物質に用いて、上記＃０１〜＃０７のリチウ
ム二次電池を作製したのと同様に、２４種類のリチウム
二次電池を作製した。なお、第１シリーズのリチウムニ
ッケル複合酸化物（＃１１〜＃１４）を正極活物質に用
いたリチウム二次電池を第１シリーズのリチウム二次電
池とし、第２シリーズのリチウムニッケル複合酸化物
（＃２１〜＃２４）を正極活物質に用いたリチウム二次
電池を第２シリーズのリチウム二次電池とし、第３シリ
ーズのリチウムニッケル複合酸化物（＃３１〜＃３４）
を正極活物質に用いたリチウム二次電池を第３シリーズ
のリチウム二次電池とし、第４シリーズのリチウムニッ
ケル複合酸化物（＃４１〜＃４４）を正極活物質に用い
たリチウム二次電池を第４シリーズのリチウム二次電池
とし、第５シリーズのリチウムニッケル複合酸化物（＃
５１〜＃５４）を正極活物質に用いたリチウム二次電池
を第５シリーズのリチウム二次電池とし、第６シリーズ
のリチウムニッケル複合酸化物（＃６１〜＃６４）を正
極活物質に用いたリチウム二次電池を第６シリーズのリ
チウム二次電池とした。(B) Lithium Secondary Battery The lithium secondary batteries of the first to sixth series were used as the positive electrode active materials, respectively. Various kinds of lithium secondary batteries were produced. A lithium secondary battery using the first series lithium-nickel composite oxide (# 11 to # 14) as a positive electrode active material is referred to as a first series lithium secondary battery, and a second series lithium-nickel composite oxide ( A lithium secondary battery using # 21 to # 24) as a positive electrode active material is referred to as a second series lithium secondary battery, and a third series lithium nickel composite oxide (# 31 to # 34)
A lithium secondary battery using as a positive electrode active material is a third series of lithium secondary batteries, and a fourth series lithium secondary battery using a lithium nickel composite oxide (# 41 to # 44) as a positive electrode active material is used. The fourth series of lithium secondary batteries is the same as the fifth series of lithium nickel composite oxide (#
Lithium secondary batteries using 51 to # 54) as positive electrode active materials were used as fifth series lithium secondary batteries, and sixth series lithium nickel composite oxides (# 61 to # 64) were used as positive electrode active materials. The lithium secondary battery was designated as a sixth series lithium secondary battery.
【００７１】（ｃ）リチウム二次電池の保存特性の評価 上記第１〜６シリーズの各リチウム二次電池について保
存特性を評価すべく、上記＃０１〜＃０７の二次電池の
保存特性の評価で行ったのと同様に、コンディショニン
グ、初期容量の測定、および保存試験を行った。そし
て、保存試験後の各電池を温度２０℃下にてそれぞれ放
電した時の容量を測定して残存容量とし、式［残存容量
／初期容量×１００］から容量残存率を求めた。(C) Evaluation of storage characteristics of lithium secondary batteries In order to evaluate the storage characteristics of each of the first to sixth series lithium secondary batteries, evaluation of storage characteristics of secondary batteries # 01 to # 07 was performed. Conditioning, measurement of the initial capacity, and storage test were performed in the same manner as in the above. Then, the capacity when each battery after the storage test was discharged at a temperature of 20 ° C. was measured to determine the remaining capacity, and the capacity remaining rate was determined from the formula [remaining capacity / initial capacity × 100].
【００７２】第１〜６シリーズの各二次電池について、
正極活物質であるリチウムニッケル複合酸化物の１次粒
子の平均粒径と容量残存率との関係を図２に示す。図２
から明らかなように、本発明のリチウムニッケル複合酸
化物を用いた＃１２、＃１３、＃２２、および＃２３の
二次電池は、容量残存率が約９０％と高い値となった。
一方、１次粒子の平均粒径が１μｍ以上４μｍ以下のリ
チウムニッケル複合酸化物を正極活物質に用いた二次電
池であっても、そのリチウムニッケル複合酸化物の組成
が本発明のリチウムニッケル複合酸化物の組成と異なる
ものを用いた二次電池は、容量残存率が約５０〜７０％
と低下している。For each of the secondary batteries of the first to sixth series,
FIG. 2 shows the relationship between the average particle size of the primary particles of the lithium nickel composite oxide as the positive electrode active material and the residual capacity ratio. FIG.
As is clear from the above, the secondary batteries # 12, # 13, # 22, and # 23 using the lithium nickel composite oxide of the present invention had a high remaining capacity of about 90%.
On the other hand, even in a secondary battery using a lithium nickel composite oxide having an average primary particle diameter of 1 μm or more and 4 μm or less as a positive electrode active material, the composition of the lithium nickel composite oxide is A secondary battery using a material different from the oxide composition has a remaining capacity ratio of about 50 to 70%.
And has declined.
【００７３】本発明のリチウムニッケル複合酸化物の組
成と異なる組成として、例えば、Ｃｏの置換割合が１０
％未満であるリチウムニッケル複合酸化物を用いた場合
には（図中▼印）、Ｃｏの置換量が少ないために、結晶
構造が充分に安定化されていないと考えられる。反対
に、Ｃｏの置換割合が２０％を超えるリチウムニッケル
複合酸化物を用いた場合には（図中■印）、Ｃｏの置換
量が多いために、リチウムニッケル複合酸化物の結晶性
が低下したと考えられる。また、Ａｌの置換割合が５％
未満のリチウムニッケル複合酸化物を用いた場合には
（図中◆印）、Ａｌの置換量が少ないために、結晶構造
の熱安定性が充分ではないと考えられる。反対に、Ａｌ
の置換割合が１０％を超えるリチウムニッケル複合酸化
物を用いた場合には（図中▲印）、Ａｌの置換量が多い
ために、格子歪みが大きく、容量残存率が低下したもの
と考えられる。As a composition different from the composition of the lithium nickel composite oxide of the present invention, for example, the substitution ratio of Co is 10
%, It is considered that the crystal structure is not sufficiently stabilized because the amount of substitution of Co is small. Conversely, when a lithium-nickel composite oxide having a Co substitution ratio of more than 20% was used (indicated by ■ in the figure), the crystallinity of the lithium-nickel composite oxide was reduced due to a large amount of Co substitution. it is conceivable that. The replacement ratio of Al is 5%.
When a lithium-nickel composite oxide of less than (（in the figure) is used, it is considered that the thermal stability of the crystal structure is not sufficient because the amount of Al substitution is small. Conversely, Al
It is considered that when a lithium-nickel composite oxide having a substitution ratio of more than 10% was used (indicated by ▲ in the figure), since the substitution amount of Al was large, the lattice distortion was large and the residual capacity ratio was lowered. .
【００７４】さらに、１次粒子の平均粒径が０．２μｍ
のリチウムニッケル複合酸化物を用いた場合には、その
組成で差はあるものの、容量残存率は約４０〜６５％と
低い値となっている。これは、リチウムニッケル複合酸
化物の比表面積が大きいため、電解液との反応が促進さ
れたためと考えられる。また、５μｍのリチウムニッケ
ル複合酸化物を用いた場合も、その組成で差はあるもの
の、容量残存率は約３５〜５５％と低い値となってい
る。これは、１次粒子が大きくなりすぎると、それに伴
い２次粒子も大きくなるため、正極においてリチウムニ
ッケル複合酸化物が均一に存在していないためと考えら
れる。Further, the average primary particle size is 0.2 μm.
When the lithium nickel composite oxide is used, the residual capacity is a low value of about 40 to 65%, although there is a difference in the composition. This is presumably because the lithium nickel composite oxide has a large specific surface area, so that the reaction with the electrolytic solution was promoted. Also, when a lithium nickel composite oxide of 5 μm is used, the capacity remaining ratio is a low value of about 35 to 55%, although there is a difference in the composition. This is presumably because, when the primary particles become too large, the secondary particles also become large, so that the lithium nickel composite oxide is not uniformly present in the positive electrode.
【００７５】したがって、本発明のリチウムニッケル複
合酸化物は、充電率の高い状態で長期間保存した場合で
あっても、容量残存率の高い、すなわち大きな容量が維
持できる二次電池を構成し得ることが確認できた。Therefore, the lithium-nickel composite oxide of the present invention can constitute a secondary battery having a high capacity remaining rate, that is, a large capacity can be maintained even when stored for a long time at a high charge rate. That was confirmed.
【００７６】以上より、本発明のリチウムニッケル複合
酸化物を正極活物質として用いたリチウム二次電池は、
充電率の高い状態で長期間保存しても、容量の減少が少
なく、かつ内部抵抗の上昇の小さいリチウム二次電池で
あることが確認できた。As described above, a lithium secondary battery using the lithium nickel composite oxide of the present invention as a positive electrode active material is:
It was confirmed that the lithium secondary battery had a small decrease in capacity and a small increase in internal resistance even when stored for a long time at a high charge rate.
【００７７】[0077]
【発明の効果】本発明のリチウムニッケル複合酸化物
は、その結晶構造が安定化されており、電解液との反応
も抑制されるため、これを正極活物質として二次電池を
構成した場合には、充電状態で長期間保存しても容量の
減少が小さく、かつ内部抵抗の上昇が少ない、保存特性
に優れたリチウム二次電池となる。The crystal structure of the lithium-nickel composite oxide of the present invention is stabilized, and the reaction with the electrolytic solution is also suppressed. Is a lithium secondary battery having excellent storage characteristics, with a small decrease in capacity and a small increase in internal resistance even when stored for a long time in a charged state.
【図１】 ＃０１〜＃０７の二次電池について、初期容
量と内部抵抗増加率との関係を示す。FIG. 1 shows the relationship between the initial capacity and the rate of increase in internal resistance for secondary batteries # 01 to # 07.
【図２】 第１〜６シリーズの各二次電池について、正
極活物質であるリチウムニッケル複合酸化物の１次粒子
の平均粒径と容量残存率との関係を示す。FIG. 2 shows the relationship between the average particle size of primary particles of lithium nickel composite oxide as a positive electrode active material and the residual capacity ratio for each of the first to sixth series secondary batteries.
フロントページの続き (72)発明者 右京 良雄 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 Ｆターム(参考） 4G048 AA04 AC06 AD04 5H029 AJ04 AK03 AL06 AL07 AL08 AL12 AM02 AM03 AM04 AM05 AM07 DJ16 HJ02 HJ05 5H050 AA09 BA16 BA17 CA08 FA17 HA02 HA05 Continuation of the front page (72) Inventor Yoshio Ukyo 41-41, Chuchu-ji, Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-term in Toyota Central R & D Laboratories Co., Ltd. 4G048 AA04 AC06 AD04 5H029 AJ04 AK03 AL06 AL07 AL08 AL12 AM02 AM03 AM04 AM05 AM07 DJ16 HJ02 HJ05 5H050 AA09 BA16 BA17 CA08 FA17 HA02 HA05
Claims (2)
2（０．１≦ｘ≦０．２；０．０５≦ｙ≦０．１）で表
され、平均粒径で１μｍ以上４μｍ以下の１次粒子が凝
集して２次粒子を形成した粒子構造をもつリチウム二次
電池正極活物質用リチウムニッケル複合酸化物。1. Composition formula LiNi 1-xy Co x Al y O
2 (0.1 ≦ x ≦ 0.2; 0.05 ≦ y ≦ 0.1), a particle structure in which primary particles having an average particle diameter of 1 μm or more and 4 μm or less are aggregated to form secondary particles. Lithium-nickel composite oxide for lithium secondary battery positive electrode active material with
０μｍ以下である請求項１に記載のリチウム二次電池正
極活物質用リチウムニッケル複合酸化物。2. The secondary particles have an average particle size of not less than 5 μm and not more than 3 μm.
The lithium-nickel composite oxide for a lithium secondary battery positive electrode active material according to claim 1, having a thickness of 0 µm or less.
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| JPH11219706A (en) * | 1998-01-30 | 1999-08-10 | Dowa Mining Co Ltd | Positive electrode active material for lithium ion secondary battery, manufacture thereof and lithium ion secondary battery |
| JP2000030693A (en) * | 1998-07-10 | 2000-01-28 | Sumitomo Metal Mining Co Ltd | Positive electrode active material for nonaqueous electrolyte secondary battery and its manufacture |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008037749A (en) * | 1996-08-12 | 2008-02-21 | Toda Kogyo Corp | Lithium nickel cobalt composite oxide, its manufacturing method and cathode active material for secondary battery |
| JP2012518871A (en) * | 2009-02-20 | 2012-08-16 | ユミコア ソシエテ アノニム | Non-homogeneous positive electrode material that combines high safety and high output in a Li battery |
| WO2020175360A1 (en) | 2019-02-28 | 2020-09-03 | パナソニックＩｐマネジメント株式会社 | Non-aqueous electrolyte rechargeable battery |
| WO2022250146A1 (en) * | 2021-05-28 | 2022-12-01 | ソニーグループ株式会社 | Information processing device and information processing method |
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