JPH09259928A - Manufacture of secondary lithium battery - Google Patents
Manufacture of secondary lithium batteryInfo
- Publication number
- JPH09259928A JPH09259928A JP8066684A JP6668496A JPH09259928A JP H09259928 A JPH09259928 A JP H09259928A JP 8066684 A JP8066684 A JP 8066684A JP 6668496 A JP6668496 A JP 6668496A JP H09259928 A JPH09259928 A JP H09259928A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- negative electrode
- charging
- battery
- lithium
- 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.)
- Pending
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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Secondary Cells (AREA)
- Carbon And Carbon Compounds (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、リチウム二次電池
の製造法の改良に関するものである。TECHNICAL FIELD The present invention relates to an improvement in a method for manufacturing a lithium secondary battery.
【０００２】[0002]
【従来の技術】近年、電子機器のポータルブル化、コー
ドレス化が急速に進んでおり、これらの駆動用電源とし
て小型、軽量で高エネルギー密度を有する二次電池への
要望が強まっている。そのため、高電圧、高エネルギー
密度を有する非水系二次電池、とりわけリチウム二次電
池に対する期待が大きくなっている。このような中で、
ＬｉＣｏＯ2を正極活物質に、リチウムをインターカレ
ート／デインターカレートする炭素材料を負極にそれぞ
れ用いたリチウム二次電池が既に開発、商品化されてい
る。ＬｉＣｏＯ2は、作動電位がリチウムの電位に対し
て約４Ｖと高く、したがって、ＬｉＣｏＯ2を活物質に
用いることにより、電池電圧を高くすることができる。
さらに、負極に炭素材料を用いてリチウムのインターカ
レーション反応を利用することにより、金属リチウムを
負極に使用した場合のデンドライト状リチウムの生成に
よる充放電効率の低下や安全面等の課題を解決すること
が可能となった。2. Description of the Related Art In recent years, electronic devices have been rapidly made portalable and cordless, and there has been an increasing demand for secondary batteries having a small size, a light weight and a high energy density as a power source for driving them. Therefore, expectations for non-aqueous secondary batteries having high voltage and high energy density, especially lithium secondary batteries, are increasing. In this way,
Lithium secondary batteries using LiCoO 2 as a positive electrode active material and a carbon material for intercalating / deintercalating lithium as a negative electrode have already been developed and commercialized. LiCoO 2 has a high operating potential of about 4 V with respect to the potential of lithium, and therefore by using LiCoO 2 as the active material, the battery voltage can be increased.
Further, by utilizing the intercalation reaction of lithium by using a carbon material for the negative electrode, problems such as reduction in charge / discharge efficiency due to generation of dendrite-like lithium and safety aspects when metallic lithium is used for the negative electrode are solved. It has become possible.
【０００３】しかしながら、ＬｉＣｏＯ2は、充電電位
が高いこともあり、充電状態におけるＬｉ1-XＣｏＯ2の
ｘの値は０．５程度と小さく、可逆容量は、正極比容量
に換算して１３５ｍＡｈ／ｇ程度が限界となる。一方、
負極に用いる炭素材料の比容量は、その種類によるもの
の、一般に２００〜２５０ｍＡｈ／ｇである。したがっ
て、小型電子機器の急速な高性能化、軽量化に対応した
より高容量、高エネルギー密度を有するリチウム二次電
池の開発にあたっては、正極、負極ともに高容量化させ
る必要があり、さらにそれらの最適な組み合わせで用い
る必要がある。However, since LiCoO 2 has a high charging potential, the value of x of Li 1 -X CoO 2 in the charged state is small, about 0.5, and the reversible capacity is 135 mAh in terms of the positive electrode specific capacity. The limit is about / g. on the other hand,
Although the specific capacity of the carbon material used for the negative electrode depends on its type, it is generally 200 to 250 mAh / g. Therefore, in developing a lithium secondary battery having higher capacity and higher energy density corresponding to rapid performance improvement and weight reduction of small electronic devices, it is necessary to increase the capacity of both the positive electrode and the negative electrode. It is necessary to use the optimal combination.
【０００４】正極活物質については、最近になって、Ｌ
ｉＣｏＯ2と同様の六方晶系の結晶構造を持つ層状化合
物であるＬｉＮｉＯ2を中心とするリチウム含有複合酸
化物が注目を集めている。例えば、米国特許第４，３０
２，５１８号に報告されているＬｉＮｉＯ2は、充電電
位がＬｉＣｏＯ2に比べて低く、同じ充電電位ではデイ
ンタカレートし得るリチウム量が多い。したがって２０
０ｍＡｈ／ｇ近くの正極比容量を持ち、比較的可逆性も
優れる。また、例えば、特開昭６３−２９９０５６号公
報には、ＬｉＮｉＯ2の改良としてＮｉの一部を他の元
素で置換した材料なども提案されている。Regarding the positive electrode active material, L
Lithium-containing composite oxides centering on LiNiO 2 , which is a layered compound having a hexagonal crystal structure similar to iCoO 2 , have been attracting attention. For example, US Pat. No. 4,30
The charging potential of LiNiO 2 reported in No. 2,518 is lower than that of LiCoO 2, and the amount of lithium that can be deintercalated at the same charging potential is large. Therefore 20
It has a positive electrode specific capacity close to 0 mAh / g and is relatively excellent in reversibility. Further, for example, JP-A-63-299056 proposes a material in which a part of Ni is replaced with another element as an improvement of LiNiO 2 .
【０００５】一方、負極に用いる炭素材料であるが、こ
れまで負極として使用可能な炭素材料は多種にわたって
いるが、大きくはコークスやガラス状炭素などの比較的
低温で熱処理を施した低結晶性炭素を用いる場合と、天
然黒鉛や人造黒鉛に代表される３０００℃近くの高温熱
履歴を有する高結晶性の黒鉛材料を用いる場合の２種に
大別される。On the other hand, regarding the carbon material used for the negative electrode, there have been various carbon materials usable as the negative electrode up to now, but largely, low crystalline carbon such as coke and glassy carbon which has been heat-treated at a relatively low temperature. And a case of using a highly crystalline graphite material having a high-temperature thermal history near 3000 ° C., which is represented by natural graphite and artificial graphite.
【０００６】ＬｉＮｉＯ2を活物質に用いた正極は、放
電容量がサイクル初期では１９０ｍＡｈ／ｇ程度の比容
量が得られるものの、サイクル数の増加に伴う容量劣化
が著しく、約５０サイクルで容量は初期の６５％程度に
まで低下する。Ｎｉの一部をＣｏで置換したＬｉＮｉ
1-XＣｏXＯ2を活物質に用いた正極は、放電容量の低下
を抑え、ＬｉＮｉＯ2に比べてサイクル特性を向上させ
ることできる。しかしながら、ＬｉＮｉ1-XＣｏXＯ2を
含むＬｉＮｉＯ2系の正極活物質は、ＬｉＣｏＯ2に比
べ、比容量が大きい反面、放電電位の傾斜が大きく、さ
らに平均電圧は約０．１Ｖ低い。したがって、負極に用
いる炭素材料としては、フラットかつ卑な電位を持つ材
料に制限される。かかる観点から、負極炭素材として
は、高結晶性の黒鉛質材料が有力な候補となり、その最
適化が重要となる。The positive electrode using LiNiO 2 as the active material has a specific capacity of about 190 mAh / g at the beginning of the cycle, but the capacity deteriorates significantly as the number of cycles increases. Of about 65%. LiNi in which a part of Ni is replaced by Co
The positive electrode using 1-X Co X O 2 as an active material can suppress a decrease in discharge capacity and can improve cycle characteristics as compared with LiNiO 2 . However, although the LiNiO 2 -based positive electrode active material containing LiNi 1 -X Co X O 2 has a larger specific capacity than LiCoO 2 , the discharge potential has a large slope and the average voltage is about 0.1 V lower. Therefore, the carbon material used for the negative electrode is limited to a material having a flat and base potential. From this point of view, as the negative electrode carbon material, a highly crystalline graphite material is a strong candidate, and its optimization is important.
【０００７】電池を組み立てた後の最初の充電条件が、
電池性能に影響を与えることが報告されている。特開平
４−１６７３４号公報には、負極の単位面積当たりの電
気量を０．５ｍＡｈ／ｃｍ2以上とし、負極に金属リチ
ウムを析出させない電気量で充電操作を行うことが提案
されている。The first charging condition after the battery is assembled is
It has been reported to affect battery performance. Japanese Unexamined Patent Publication (Kokai) No. 4-16734 proposes that the amount of electricity per unit area of the negative electrode is 0.5 mAh / cm 2 or more, and the charging operation is performed with an amount of electricity that does not deposit metallic lithium on the negative electrode.
【０００８】[0008]
【発明が解決しようとする課題】リチウム二次電池の高
容量化、高エネルギー密度化にあたって、正極活物質に
は現行のＬｉＣｏＯ2に代わる材料としてＬｉＮｉ1-XＣ
ｏXＯ2を、負極には高結晶性の黒鉛材料をそれぞれ用い
た電池が提案されている。例えば、特開平７−３２０７
２１号公報には、正極活物質にＬｉＮｉ1-XＣｏXＯ2を
用い、負極に炭素材料を用いたリチウム二次電池が提案
されている。また、特開平７−３２０７８５号公報に
は、正極活物質にＬｉＮｉ1-XＣｏXＯ2を用い、負極に
黒鉛材料を用いたリチウム二次電池が提案されている。In order to increase the capacity and energy density of a lithium secondary battery, LiNi 1-X C is used as a positive electrode active material as an alternative material to the current LiCoO 2.
Batteries using o X O 2 and a highly crystalline graphite material for the negative electrode have been proposed. For example, JP-A-7-3207
Japanese Patent Laid - Open No. 21 discloses a lithium secondary battery in which LiNi 1-X Co X O 2 is used as a positive electrode active material and a carbon material is used as a negative electrode. Further, JP-A-7-320785 proposes a lithium secondary battery in which LiNi 1-X Co X O 2 is used as a positive electrode active material and a graphite material is used as a negative electrode.
【０００９】Ｌｉ1-xＮｉ1-yＣｏyＯ2は、充電によりｘ
＝０．８程度までリチウムがデインターカレートする。
このときの正極比容量は、１９０ｍＡｈ／ｇ以上と、Ｌ
ｉＣｏＯ2と比べて大きな値を示す。その反面、ＬｉＣ
ｏＯ2等に比べ、最初の充電によって電極内でデインタ
ーカレートするリチウム量のバラツキが大きくなる傾向
がある。電極の表面積が大きくなるほど、また厚みが大
きくなるほど、電極内の充電状態にバラツキが生じるよ
うになり、ｘ値の異なる充電状態が同一電極内に存在す
ることになる。一度このような充電バラツキが生じる
と、その後に充放電やエージングを繰り返しても元には
戻らず、容量低下を引き起こすと共にサイクル特性に大
きな影響を与える。Li 1-x Ni 1-y Co y O 2 is x-charged by charging.
= Li deintercalates up to about 0.8.
At this time, the positive electrode specific capacity is 190 mAh / g or more, and L
It shows a larger value than that of iCoO 2 . On the other hand, LiC
The variation in the amount of lithium deintercalated in the electrode by the first charge tends to be larger than that of oO 2 or the like. The larger the surface area of the electrode and the larger the thickness thereof, the more the state of charge within the electrode varies, and the state of charge with different x values exists within the same electrode. Once such a charge variation occurs, it will not be restored even after repeated charging and discharging or aging, causing a capacity decrease and having a great influence on the cycle characteristics.
【００１０】また、例えば、特開平７ー３２０７８５号
公報に記載されたような、従来から知られている、ニッ
ケル塩、コバルト塩およびリチウム化合物を混合し、熱
処理を施すといった方法によりＬｉＮｉ1-xＣｏxＯ2を
合成すると、ある程度固溶はするものの一部未反応相が
残存したり、あるいはＬｉＣｏＯ2が生成されたりす
る。このような不純物質が存在すると、正極比容量の低
下を招くとともに、充放電時の相変化が大きいためにサ
イクル特性が大きく低下する。Further, for example, as described in Japanese Patent Laid-Open No. 7-320785, a conventionally known method of mixing a nickel salt, a cobalt salt and a lithium compound and subjecting the mixture to a heat treatment may be applied to LiNi 1-x. When Co x O 2 is synthesized, it forms a solid solution to some extent but some unreacted phase remains, or LiCoO 2 is produced. The presence of such an impurity causes a decrease in the specific capacity of the positive electrode, and a large phase change at the time of charging / discharging, which greatly deteriorates the cycle characteristics.
【００１１】本発明は、このような問題点を解決し、高
容量、高エネルギー密度を有し、かつサイクル特性など
電池諸特性に優れたリチウム二次電池の製造法を提供す
ることを目的とする。An object of the present invention is to solve the above problems and to provide a method for producing a lithium secondary battery having a high capacity, a high energy density and excellent battery characteristics such as cycle characteristics. To do.
【００１２】[0012]
【課題を解決するための手段】本発明のリチウム二次電
池の製造法では、正極活物質は、ニッケル塩とコバルト
塩との混合水溶液にアルカリ溶液を加えて共沈させて得
たニッケルとコバルトの複合水酸化物を合成し、この複
合水酸化物とリチウム化合物の混合物を熱処理して得ら
れる。また、負極黒鉛は、メソフェーズ小球体を黒鉛化
したもの、あるいは人造黒鉛粒子を核としてその表面に
低結晶性の炭素物質を一部被覆した改質人造黒鉛のいず
れかであって、それらの粉末Ｘ線回折法により測定した
００２面の面間隔（ｄ002）が３．３５オングストロー
ム〜３．３９オングストロームのものである。In the method for manufacturing a lithium secondary battery of the present invention, the positive electrode active material is nickel and cobalt obtained by adding an alkaline solution to a mixed aqueous solution of a nickel salt and a cobalt salt and coprecipitating the same. It is obtained by synthesizing the above composite hydroxide and heat treating a mixture of this composite hydroxide and a lithium compound. Further, the negative electrode graphite is either graphitized mesophase spherules or modified artificial graphite in which artificial graphite particles are used as nuclei to partially coat a low crystalline carbon substance on the surface thereof, and powders thereof are used. The interplanar spacing (d 002 ) of 002 planes measured by X-ray diffractometry is 3.35 Å to 3.39 Å.
【００１３】[0013]
【発明の実施の形態】本発明のリチウム二次電池の製造
法は、ニッケル塩とコバルト塩の混合水溶液にアルカリ
溶液を加える共沈法によって合成したＮｉ1-xＣｏx（Ｏ
Ｈ）2およびリチウム化合物の混合物を熱処理して、Ｌ
ｉＮｉ1-xＣｏxＯ2（但し、０．１０≦ｘ≦０．３０と
する）で表されるリチウム含有複合酸化物を合成する工
程と、リチウム含有複合酸化物を活物質とする正極と、
黒鉛化されたメソフェーズ小球体、または表面に低結晶
性の炭素質層を一部被覆した人造黒鉛粒子を負極に用い
た電池を組み立てる工程と、電池を、負極の正極と対向
する部分の表面電流密度を０．５ｍＡ／ｃｍ2以下と
し、充電電気量を正極比容量１００ｍＡｈ／ｇ以上、２
１０ｍＡｈ／ｇ以下として充電する工程を含むものであ
る。BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing a lithium secondary battery according to the present invention is Ni 1-x Co x (O) synthesized by a coprecipitation method in which an alkaline solution is added to a mixed aqueous solution of a nickel salt and a cobalt salt.
H) 2 and a lithium compound are heat treated to produce L
a step of synthesizing a lithium-containing composite oxide represented by iNi 1-x Co x O 2 (provided that 0.10 ≦ x ≦ 0.30), and a positive electrode using the lithium-containing composite oxide as an active material ,
The process of assembling a battery that uses graphitized mesophase spheres or artificial graphite particles partially coated with a low-crystalline carbonaceous layer on the surface of the negative electrode, and the surface current of the part of the battery facing the positive electrode The density is 0.5 mA / cm 2 or less, and the charge electricity quantity is positive electrode specific capacity 100 mAh / g or more, 2
It includes a step of charging at 10 mAh / g or less.
【００１４】さらに、負極表面電流密度が、０．３ｍＡ
／ｃｍ2以下であることが好ましい。また、前記黒鉛の
結晶面００２面の面間隔が３．３５オングストローム〜
３．３９オングストロームであることが好ましい。Further, the surface current density of the negative electrode is 0.3 mA.
/ Cm 2 or less is preferable. Further, the crystal plane 002 of the graphite has a surface spacing of 3.35 angstroms or more.
It is preferably 3.39 angstroms.
【００１５】高容量、且つ良好なサイクル特性を有する
非水電解液二次電池を得るためには、正極活物質の合成
法が重要である。つまり、特性の優れた正極活物質を得
るためには、ＮｉとＣｏが完全に固溶した複合酸化物で
あることが要求される。すなわち、粉末Ｘ線回折法によ
って得られる情報として、六方晶に帰属される単一層の
ピークのみが検出され、且つ充電状態においても単一層
のみのピークが見られる必要がある。本発明による正極
活物質の合成法では、あらかじめニッケル塩とコバルト
塩との混合水溶液にアルカリ溶液を加えてニッケルとコ
バルトの水酸化物を共沈させる（以下、共沈法と呼
ぶ）。これにより得られた複合水酸化物にリチウム化合
物を混合し、この混合物を熱処理してリチウム含有複合
酸化物ＬｉＮｉ1-xＣｏxＯ2を得る。この合成法による
と、完全な固溶体が得られる。このリチウム含有複合酸
を正極活物質に用いた場合、充放電時の相変化を伴わな
いために優れたサイクル特性が得られる。ここで、Ｃｏ
の固溶量は、０．１０≦ｘ≦０．３０であることが要求
される。ｘが０．１０未満では、Ｃｏを固溶した効果が
充分に得られず、サイクル特性を満足できない。一方、
ｘが０．３０を超えた場合は、容量低下を招き、好まし
くない。In order to obtain a non-aqueous electrolyte secondary battery having high capacity and good cycle characteristics, a method for synthesizing a positive electrode active material is important. That is, in order to obtain a positive electrode active material having excellent characteristics, a composite oxide in which Ni and Co are completely dissolved is required. That is, as the information obtained by the powder X-ray diffraction method, it is necessary that only the peak of a single layer belonging to the hexagonal crystal is detected and that the peak of only the single layer is seen even in the charged state. In the method for synthesizing the positive electrode active material according to the present invention, an alkaline solution is previously added to a mixed aqueous solution of a nickel salt and a cobalt salt to coprecipitate nickel and cobalt hydroxides (hereinafter referred to as a coprecipitation method). A lithium compound is mixed with the composite hydroxide thus obtained, and the mixture is heat-treated to obtain a lithium-containing composite oxide LiNi 1-x Co x O 2 . According to this synthetic method, a complete solid solution is obtained. When this lithium-containing composite acid is used as the positive electrode active material, excellent cycle characteristics can be obtained because there is no phase change during charge / discharge. Where Co
The solid solution amount of is required to be 0.10 ≦ x ≦ 0.30. If x is less than 0.10, the effect of solid solution of Co cannot be sufficiently obtained, and the cycle characteristics cannot be satisfied. on the other hand,
When x exceeds 0.30, the capacity is lowered, which is not preferable.
【００１６】また、高容量の電池を得るためには、高結
晶性の黒鉛負極の選択が重要であるが、天然黒鉛や人造
黒鉛などをこのような負極に用いた場合、その大きな異
方性と配向性のために黒鉛のｃ軸が電極面と垂直方向に
配置されるため、リチウムのインターカレート／デイン
ターカレートを阻害する形となり、特に高率充放電時の
容量特性に影響を及ぼす。Further, in order to obtain a high capacity battery, it is important to select a highly crystalline graphite negative electrode, but when natural graphite or artificial graphite is used for such a negative electrode, its large anisotropy is caused. Since the graphite c-axis is arranged in the direction perpendicular to the electrode surface due to the orientation, the intercalation / deintercalation of lithium is hindered, and the capacity characteristics at high rate charge / discharge are affected. Exert.
【００１７】ピッチの炭素化過程で得られるメソフェー
ズ小球体を黒鉛化したもの（以下、メソフェーズ黒鉛と
呼ぶ）を負極に用いた場合、容量の低下を抑制すること
ができる。このメソフェーズ黒鉛は、粒子そのものは異
方性であり、易黒鉛化性であるが、球状形態であること
もあって粉末全体としては等方性であり、電極にした場
合においても比較的ランダムな配向をとる。そのため
に、高率充放電時においても高容量を得ることが可能と
なる。また、人造黒鉛粒子を核として、その表面に低結
晶性の炭素質相を一部被覆した改質人造黒鉛を負極に用
いた場合も、メソフェーズ黒鉛と同様な効果が得られ
る。通常、被覆する炭素質相の割合は、５％〜１５％程
度が好ましく、それ以上の被覆量は、電池容量の低下に
つながるので好ましくない。When a graphitized mesophase small sphere obtained in the carbonization process of pitch (hereinafter referred to as mesophase graphite) is used for the negative electrode, a decrease in capacity can be suppressed. The particles of this mesophase graphite have anisotropy and are easily graphitizable, but since they have a spherical shape, they are isotropic as a whole powder, and even when they are used as electrodes, they are relatively random. Take orientation. Therefore, it is possible to obtain a high capacity even during high-rate charging / discharging. In addition, when the artificial graphite having the artificial graphite particles as the nucleus and the surface thereof partially covered with the low crystalline carbonaceous phase is used for the negative electrode, the same effect as that of the mesophase graphite can be obtained. Usually, the ratio of the carbonaceous phase to be coated is preferably about 5% to 15%, and a coating amount of more than 5% is not preferable because it leads to a decrease in battery capacity.
【００１８】最初の充電が、０．５ｍＡ／ｃｍ2以下と
いった非常に小さな負極表面電流密度で、その充電電気
量が正極比容量１００ｍＡｈ／ｇ以上、２１０ｍＡｈ／
ｇ以下の充電操作を１回以上行うことにより、上述のよ
うな充電バラツキはほとんど生じない。そして、以後、
高率充放電を行っても、充電バラツキが生じるようなこ
とはない。これは、１回目の充電と２回目以降の充電で
はリチウムがデインターカレートした際の正極の結晶構
造が微妙に変化することに起因している。The first charge was a very small negative electrode surface current density of 0.5 mA / cm 2 or less, and the amount of charge was 100 mAh / g or more and 210 mAh / g of positive electrode specific capacity.
By performing the charging operation of g or less once or more, the above-mentioned charging variation hardly occurs. And after that,
Even if the high-rate charging / discharging is performed, the charging variation does not occur. This is due to a slight change in the crystal structure of the positive electrode when lithium is deintercalated between the first charge and the second and subsequent charges.
【００１９】負極についても、特に高結晶性の黒鉛を用
いる場合、正極と全く同様な挙動が見られ、最初の充電
条件によって電極内の充電バラツキの状態が変化するた
めに低電流密度での充電が重要である。やはり１回目の
充電と２回目以降の充電では、リチウムがインターカレ
ートされた黒鉛層間化合物の状態が異なることによるも
のである。また、更に好ましい表面電流密度は、０．３
ｍＡ／ｃｍ2以下である。充電電気量としては、正極比
容量１００ｍＡｈ／ｇ以上は必要であり、それ未満では
効果が充分に得られない。一方、２１０ｍＡｈ／ｇを超
えると負極表面に金属リチウムが析出するなどの弊害が
見られるので好ましくない。Regarding the negative electrode as well, particularly when highly crystalline graphite is used, the same behavior as that of the positive electrode is observed, and the state of charge variation in the electrode changes depending on the initial charging condition, so charging at low current density is performed. is important. This is because the state of the graphite intercalation compound in which lithium is intercalated is different between the first charge and the second and subsequent charges. A more preferable surface current density is 0.3
It is mA / cm 2 or less. As the charge electricity quantity, a positive electrode specific capacity of 100 mAh / g or more is necessary, and if it is less than that, the effect cannot be sufficiently obtained. On the other hand, if it exceeds 210 mAh / g, adverse effects such as deposition of metallic lithium on the surface of the negative electrode are observed, which is not preferable.
【００２０】[0020]
【実施例】以下、本発明の実施例を詳しく述べる。 《実施例１》図１に示す円筒形リチウム二次電池を、以
下のようにして作製した。正極板および負極板をセパレ
ータを挟んで重ね合わせ、渦巻状に捲回した極板群４
が、耐有機電解液性のステンレス鋼板を加工した電池ケ
ース１の内部に収納されている。そして正極板から引き
出された正極リード５は、封口板２に接続されており、
負極板から引き出された負極リード６は、電池ケース１
の底部に接続されている。極板群４の上下部には、それ
ぞれ絶縁リング７が設けられている。電池ケース１の開
口部には、安全弁を備えた封口板２が、絶縁パッキング
３をはさんで嵌合されており、電池ケース１と封口板２
は電気的に絶縁されている。EXAMPLES Examples of the present invention will be described in detail below. Example 1 The cylindrical lithium secondary battery shown in FIG. 1 was produced as follows. Electrode plate group 4 in which a positive electrode plate and a negative electrode plate are superposed with a separator sandwiched therebetween and spirally wound.
Is housed inside the battery case 1 which is made of a stainless steel plate having organic electrolyte resistance. The positive electrode lead 5 drawn out from the positive electrode plate is connected to the sealing plate 2,
The negative electrode lead 6 pulled out from the negative electrode plate is the battery case 1
Attached to the bottom of. Insulating rings 7 are provided on the upper and lower portions of the electrode plate group 4, respectively. A sealing plate 2 equipped with a safety valve is fitted in the opening of the battery case 1 with an insulating packing 3 sandwiched between the battery case 1 and the sealing plate 2.
Are electrically insulated.
【００２１】以下、正、負極板の製造法等について詳し
く説明する。まず、Ｎｉ／Ｃｏ複合酸化物の合成法を説
明する。市販の硫酸ニッケルを水に溶解させ、飽和状態
の硫酸ニッケル水溶液を調製する。これに硫酸コバルト
を、ＮｉとＣｏのモル比が８０：２０になるように加
え、更に水を加えて硫酸コバルトを溶解させ、硫酸ニッ
ケルおよび硫酸コバルトの飽和水溶液を調製する。次い
で、攪拌しながらこの水溶液に水酸化ナトリウム水溶液
をゆっくりと加えていくと、ＮｉとＣｏの水酸化物の沈
殿（共沈）が同時に始まる。十分に水酸化ナトリウム溶
液を加えて沈殿が終了した後、ろ過して沈殿物を回収
し、水洗する。ｐＨを確認しながら水洗を繰り返し、残
存アルカリがほぼ消失した後、１００℃の熱風空気中で
乾燥する。The method of manufacturing the positive and negative electrode plates will be described in detail below. First, a method for synthesizing the Ni / Co composite oxide will be described. A commercially available nickel sulfate is dissolved in water to prepare a saturated nickel sulfate aqueous solution. Cobalt sulfate is added to this so that the molar ratio of Ni and Co is 80:20, and water is further added to dissolve the cobalt sulfate to prepare a saturated aqueous solution of nickel sulfate and cobalt sulfate. Then, when sodium hydroxide aqueous solution is slowly added to this aqueous solution with stirring, precipitation (coprecipitation) of hydroxides of Ni and Co simultaneously starts. After the sodium hydroxide solution is sufficiently added to complete the precipitation, the precipitate is collected by filtration and washed with water. Washing with water is repeated while confirming the pH, and after almost all the residual alkali has disappeared, the product is dried in hot air at 100 ° C.
【００２２】このようにして得られたＮｉ／Ｃｏ複合水
酸化物は、粉末Ｘ線回折の結果、単一相であり、また元
素分析の結果、ほぼ目的の比率でＮｉとＣｏを含んだＮ
ｉ0. 80Ｃｏ0.20（ＯＨ）2であることが確認された。な
お、本実施例では、原材料にＮｉ源として硫酸ニッケル
を、Ｃｏ源として硫酸コバルトをそれぞれ用いたが、Ｎ
ｉ源として硝酸ニッケル、Ｃｏ源として硝酸コバルトな
ど、水に溶解する塩であればいずれの塩も使用可能であ
る。また、アルカリ源として水酸化ナトリウムを用いた
が、水酸化カリウム、水酸化リチウムなど他のアルカリ
溶液であってもよい。The Ni / Co composite hydroxide thus obtained was in a single phase as a result of powder X-ray diffraction, and as a result of elemental analysis, N / Ni containing Ni and Co in almost the target ratios.
It was confirmed i 0. a 80 Co 0.20 (OH) 2. In this example, nickel sulfate was used as the Ni source and cobalt sulfate was used as the Co source in the raw material.
Any salt can be used as long as it is a salt soluble in water, such as nickel nitrate as the i source and cobalt nitrate as the Co source. Although sodium hydroxide was used as the alkali source, other alkali solutions such as potassium hydroxide and lithium hydroxide may be used.
【００２３】次いで、Ｌｉ化合物との混合、熱処理の工
程について説明する。水酸化リチウムと上記のようにし
て得られたＮｉ／Ｃｏ複合水酸化物を、ＮｉとＣｏの原
子数の和とＬｉの原子数が等量になるようにボールミル
で十分に混合した。この混合物を、アルミナ製のるつぼ
に入れ、乾燥空気中において７５０℃で１０時間熱処理
した。自然冷却後、粉砕、分級を行い平均粒径約１０μ
ｍの正極活物質粉末を得た。このようにして得られた正
極活物質は、粉末法によるＸ線構造解析の結果、ＬｉＮ
ｉ0.80Ｃｏ0.20Ｏ2の単一相を有するものであった。Next, the steps of mixing with a Li compound and heat treatment will be described. Lithium hydroxide and the Ni / Co composite hydroxide obtained as described above were thoroughly mixed in a ball mill so that the sum of the numbers of Ni and Co atoms and the number of Li atoms were equal. The mixture was placed in an alumina crucible and heat-treated in dry air at 750 ° C. for 10 hours. After natural cooling, pulverization and classification are performed and average particle size is about 10μ
m positive electrode active material powder was obtained. The positive electrode active material thus obtained was analyzed by an X-ray structural analysis by a powder method,
It had a single phase of i 0.80 Co 0.20 O 2 .
【００２４】続いて、正極板の作製方法について説明す
る。得られた正極活物質１００重量部に対してアセチレ
ンブラック１重量部を加え、さらにこの混合物に、Ｎ−
メチル−２−ピロリドン（ＮＭＰ）に結着剤としてのポ
リフッ化ビニリデン（以下ＰＶＤＦとする）を溶解した
溶液を加えて、混練してペースト状にした。なお、加え
たＰＶＤＦの量は、正極活物質１００重量部に対して４
重量部となるように調整した。次いで、このペーストを
アルミニウム箔の両面に塗布し、乾燥後、圧延して厚さ
０．１４ｍｍ、幅３７ｍｍ、長さ３８０ｍｍの正極板を
得た。なお、正極板の作製に当たっては混練以降一連の
工程は乾燥空気中で行った。Next, a method for manufacturing the positive electrode plate will be described. 1 part by weight of acetylene black was added to 100 parts by weight of the obtained positive electrode active material, and N-
A solution in which polyvinylidene fluoride (hereinafter referred to as PVDF) as a binder was dissolved in methyl-2-pyrrolidone (NMP) was added and kneaded to form a paste. The amount of PVDF added was 4 with respect to 100 parts by weight of the positive electrode active material.
It was adjusted so that it would be part by weight. Next, this paste was applied on both sides of an aluminum foil, dried, and then rolled to obtain a positive electrode plate having a thickness of 0.14 mm, a width of 37 mm, and a length of 380 mm. In the production of the positive electrode plate, a series of steps after kneading were performed in dry air.
【００２５】負極には、平均粒径６．０μｍのメソフェ
ーズ小球体を２８００℃で熱処理し、黒鉛化したメソフ
ェーズ黒鉛（ｄ002＝３．３６５オングストローム）を
使用した。このメソフェーズ黒鉛１００重量部に、結着
剤としてのスチレン／ブタジエンゴム３重量部を混合
し、さらにカルボキシメチルセルロース水溶液を加えて
混練し、ペースト状にした。そしてこのペーストを銅箔
の両面に塗布し、乾燥後、圧延して厚み０．２０ｍｍ、
幅３９ｍｍ、長さ４２０ｍｍの負極板を得た。As the negative electrode, mesophase graphite (d 002 = 3.365 angstrom) was used which was obtained by graphitizing mesophase spherules having an average particle size of 6.0 μm at 2800 ° C. 100 parts by weight of this mesophase graphite was mixed with 3 parts by weight of styrene / butadiene rubber as a binder, and an aqueous carboxymethyl cellulose solution was further added and kneaded to form a paste. Then, this paste is applied to both sides of the copper foil, dried and rolled to a thickness of 0.20 mm,
A negative electrode plate having a width of 39 mm and a length of 420 mm was obtained.
【００２６】正極にはアルミニウム製のリード、負極に
はニッケル製のリードをそれぞれ取り付け、この正極お
よび負極を、厚さ０．０２５ｍｍ、長さ１０００ｍｍ、
幅４５ｍｍのポリエチレン製のセパレータを介して渦巻
状に捲回し、直径１７．０ｍｍ、高さ５０ｍｍの電池ケ
ース１に収納した。電解液にはエチレンカーボネート
（ＥＣ）とエチルメチルカーボネート（ＥＭＣ）とを体
積比２０：８０で混合した溶媒に電解質として１モル／
リットルのＬｉＰＦ6を溶解したものを注液した。電池
ケース１の開口部に封口板２を嵌合して電池を密封し、
リチウム二次電池を得た。An aluminum lead is attached to the positive electrode and a nickel lead is attached to the negative electrode. The positive electrode and the negative electrode have a thickness of 0.025 mm and a length of 1000 mm, respectively.
It was wound in a spiral shape through a polyethylene separator having a width of 45 mm and housed in a battery case 1 having a diameter of 17.0 mm and a height of 50 mm. The electrolyte solution was prepared by mixing ethylene carbonate (EC) and ethylmethyl carbonate (EMC) at a volume ratio of 20:80 in a solvent of 1 mol / electrolyte.
What melt | dissolved LiPF6 of 1 liter was injected. The sealing plate 2 is fitted into the opening of the battery case 1 to seal the battery,
A lithium secondary battery was obtained.
【００２７】上記のようにして得たリチウム二次電池に
ついて、表１に示す充電条件で定電流充電を行った後、
放電電流２７０ｍＡで２．５Ｖまで定電流放電を行った
（それぞれ電池Ａ〜Ｈに相当）。The lithium secondary battery obtained as described above was subjected to constant current charging under the charging conditions shown in Table 1,
A constant current discharge was performed up to 2.5 V with a discharge current of 270 mA (corresponding to batteries A to H, respectively).
【００２８】[0028]
【表１】 [Table 1]
【００２９】その後、これらの電池に対して２０℃の環
境下で充放電サイクル試験を行った。充電は、すべて
４．２Ｖの定電流定電圧充電方式をとり、４．２Ｖに到
達するまでは６３０ｍＡの定電流充電を行い、４．２Ｖ
に到達後は定電圧充電に変換し、トータル２時間で充電
が終了するように設定した。放電は、すべて９００ｍＡ
の定電流放電を行い、放電終止電圧を２．５Ｖとした。
それぞれ１０サイクル目の放電容量を初期容量とし、充
電後の容量が初期容量の半分以下に劣化した時点（サイ
クル数）をサイクル寿命とした。それらの結果を図２に
示す。After that, a charge / discharge cycle test was performed on these batteries in an environment of 20 ° C. All the charging was done by the constant current constant voltage charging method of 4.2V, and the constant current charging of 630mA was performed until 4.2V was reached, and then 4.2V.
After reaching, the charging was converted to constant voltage charging, and the charging was set to be completed in 2 hours. All discharge is 900mA
Was discharged at a constant current, and the final voltage of discharge was set to 2.5V.
The discharge capacity at the 10th cycle was defined as the initial capacity, and the time (the number of cycles) at which the capacity after charging deteriorated to less than half the initial capacity was defined as the cycle life. The results are shown in FIG.
【００３０】図２より、初期容量には大差は無いが、最
初の充電を０．５ｍＡ／ｃｍ2を超える電流密度で行っ
た電池Ｇおよび電池Ｈは、他の電池に比べ、若干、容量
が小さくなった。また、サイクル特性では、他の電池に
比べると、明らかに劣る。また、電池Ａを除くと、電流
密度の低いものほどサイクル特性はよく、特に、電流密
度を０．３ｍＡ／ｃｍ2以下とした電池Ｂ〜Ｄは、優れ
たサイクル特性を示す。これは、最初の充電を０．５ｍ
Ａ／ｃｍ2を超える高い電流密度で行った場合、正、負
極電極内の活物質の状態にバラツキが生じ、これにより
その後の容量およびサイクル特性が低下したものと考え
られる。電池Ａのサイクル特性が悪い原因は、最初の充
電電気量が７５ｍＡｈ／ｇと小さく、電極内に均一な充
電状態を形成するには不十分であったことに起因すると
思われる。一方、電池Ａと同じ電流密度で、充電電気容
量を１００ｍＡｈ／ｇ以上として充電を行った電池Ｂ〜
Ｆは、いずれも容量およびサイクル特性の双方とも優れ
た性能を示す。以上の結果から、電池を組み立てた後の
最初の充電は、充電電流密度を０．５ｍＡ／ｃｍ2以
下、好ましくはサイクル特性の観点から０．３ｍＡ／ｃ
ｍ2以下とし、その充電電気量を、１００ｍＡｈ／ｇ以
上とした場合、優れた電池性能が得られる。From FIG. 2, although the initial capacities are not so different, the capacities of the batteries G and H, which were initially charged at a current density exceeding 0.5 mA / cm 2 , were slightly higher than those of the other batteries. It got smaller. Also, the cycle characteristics are clearly inferior to other batteries. Further, except for the battery A, the lower the current density is, the better the cycle characteristics are, and the batteries B to D having the current density of 0.3 mA / cm 2 or less show excellent cycle characteristics. This is the first charge 0.5m
When a high current density exceeding A / cm 2 is performed, it is considered that the state of the active material in the positive electrode and the negative electrode varies, which causes the subsequent capacity and cycle characteristics to deteriorate. It is considered that the reason why the cycle characteristic of the battery A is poor is that the initial charge electricity amount was as small as 75 mAh / g, which was insufficient for forming a uniform charge state in the electrode. On the other hand, with the same current density as the battery A, the battery B charged with the charging electric capacity of 100 mAh / g or more
F shows excellent performance in both capacity and cycle characteristics. From the above results, the first charging after assembling the battery has a charging current density of 0.5 mA / cm 2 or less, preferably 0.3 mA / c from the viewpoint of cycle characteristics.
Excellent battery performance can be obtained when the charging amount is 100 mAh / g or more and m 2 or less.
【００３１】なお、本実施例では、表１の充放電の条件
を１サイクルだけ行ったが、２サイクル以上行った後、
充放電サイクル試験を開始した場合も、ほぼ同様な効果
が得られた。また、充放電サイクル試験の前に、電池を
２０℃〜６０℃の環境下で一定期間放置（エージング）
をおこなうことも可能である。In this embodiment, the charging and discharging conditions shown in Table 1 were carried out for only one cycle, but after carrying out two or more cycles,
Similar effects were obtained when the charge / discharge cycle test was started. Before the charge / discharge cycle test, the battery is left for a certain period of time (aging) in an environment of 20 ° C to 60 ° C.
It is also possible to do.
【００３２】《実施例２》次に、共沈法において、Ｎｉ
／Ｃｏのモル比を変化させ、Ｃｏの固溶比率ｘの値が０
〜０．５０までの複合水酸化物を合成し、これらに所定
量の水酸化リチウムを混合し、７５０℃、１０時間の熱
処理を行い、種々の組成のリチウム含有複合酸化物を得
た。ｘ＝０とはＣｏを全く固溶させていないものであ
る。いずれの組成においても、粉末Ｘ線回折法による構
造解析の結果、単一相の複合酸化物が生成していること
が確認された。これらの複合酸化物を活物質として、そ
れぞれ実施例１と同様に正極板を作製した。負極には、
平均粒径１５μｍの人造黒鉛粉末（ｄ002＝３．３５８
オングストローム）１００重量部にピッチ１０重量部を
混練して、被覆し、これを１０００℃で炭素化した後、
粉砕したものを用いた。この黒鉛粉末を用いて、実施例
１と同様の負極板を作製した。これら正、負極を組み合
わせ、他の条件は実施例１と同様のリチウム二次電池を
組み立てた。Example 2 Next, in the coprecipitation method, Ni
The value of the solid solution ratio x of Co is 0 by changing the molar ratio of / Co.
A composite hydroxide of up to 0.50 was synthesized, and a predetermined amount of lithium hydroxide was mixed with these, and heat treatment was performed at 750 ° C. for 10 hours to obtain lithium-containing composite oxides of various compositions. x = 0 means that Co is not dissolved at all. As a result of structural analysis by a powder X-ray diffraction method, it was confirmed that a single-phase composite oxide was formed in any composition. A positive electrode plate was produced in the same manner as in Example 1 using these composite oxides as active materials. For the negative electrode,
Artificial graphite powder having an average particle size of 15 μm (d 002 = 3.358)
100 parts by weight of (Angstrom) and 10 parts by weight of pitch are kneaded, coated, and carbonized at 1000 ° C.,
The crushed one was used. Using this graphite powder, a negative electrode plate similar to that in Example 1 was produced. The positive and negative electrodes were combined, and a lithium secondary battery was assembled under the same conditions as in Example 1 except for the above.
【００３３】[0033]
【表２】 [Table 2]
【００３４】これらＩ〜Ｏの電池を、７５ｍＡ（０．２
７ｍＡ／ｃｍ2）の定電流で４．２Ｖまで充電し、２７
０ｍＡの定電流で２．５Ｖまで放電した。この充放電を
２サイクル行い、３サイクル目の充電状態で終了し、そ
の後、実施例１と同じ充放電条件でサイクル試験を開始
した。These I to O batteries were operated at 75 mA (0.2
Charged to 4.2V with a constant current of 7 mA / cm 2 ), 27
It was discharged to 2.5 V with a constant current of 0 mA. This charging / discharging was performed for 2 cycles and ended in the charged state of the 3rd cycle, and then the cycle test was started under the same charging / discharging conditions as in Example 1.
【００３５】《比較例１》共沈法ではなく、従来の製造
法を用いて、ＬｉＮｉ0.80Ｃｏ0.20Ｏ2の組成を有する
正極活物質を合成した。まず、水酸化ニッケル、水酸化
コバルトおよび水酸化リチウムを、Ｎｉ：Ｃｏ：Ｌｉの
原子数の比が０．８０：０．２０：１．０となるように
秤量し、ボールミルで充分に混合した。そして、この混
合物をアルミナ製のるつぼに入れ、乾燥空気中において
７５０℃で１０時間、熱処理した。自然冷却後、粉砕、
分級を行い、平均粒径約１０μｍの正極活物質粉末を得
た。粉末Ｘ線回折の結果、一部未反応相と思われるピー
クと、ＬｉＣｏＯ2と考えられるピークの存在が確認さ
れた。この活物質を用いて実施例２と同様のリチウム二
次電池を作製した。これを電池Ｐとする。この電池Ｐに
ついて実施例２と同じ充放電を行い、同様のサイクル試
験を行った。Comparative Example 1 A positive electrode active material having a composition of LiNi 0.80 Co 0.20 O 2 was synthesized by using a conventional manufacturing method instead of the coprecipitation method. First, nickel hydroxide, cobalt hydroxide, and lithium hydroxide were weighed so that the atomic ratio of Ni: Co: Li was 0.80: 0.20: 1.0, and mixed sufficiently with a ball mill. . Then, this mixture was placed in a crucible made of alumina and heat-treated in dry air at 750 ° C. for 10 hours. After natural cooling, crush,
Classification was performed to obtain a positive electrode active material powder having an average particle size of about 10 μm. As a result of powder X-ray diffraction, the existence of a peak that is considered to be a partially unreacted phase and a peak that is considered to be LiCoO 2 was confirmed. A lithium secondary battery similar to that of Example 2 was produced using this active material. This is referred to as a battery P. The same charge and discharge as in Example 2 was performed on this battery P, and the same cycle test was performed.
【００３６】《比較例２》負極の黒鉛材料に実施例２で
用いた人造黒鉛粉末を改質処理することなく、そのまま
使用し、実施例２と同様のリチウム二次電池を作製し
た。これを電池Ｑとする。そして実施例２と同じ充放電
を行い、さらに４５℃で３日間のエージングを行った
後、同様のサイクル試験を行った。Comparative Example 2 The artificial graphite powder used in Example 2 was used as it was without modification for the graphite material of the negative electrode, and a lithium secondary battery similar to that of Example 2 was produced. This is referred to as battery Q. The same charge and discharge as in Example 2 was performed, and after aging at 45 ° C. for 3 days, the same cycle test was performed.
【００３７】実施例２（電池Ｉ〜Ｏ）及び比較例１、２
の電池（電池Ｐ及び電池Ｑ）の初期容量およびサイクル
寿命の結果を図３に示す。Ｃｏの固溶量に関しては、ｘ
が０．１０〜０．３０の電池Ｋ〜Ｍが良好な特性を示し
ており、ｘが０．０５以下の電池Ｉおよび電池Ｊでは、
初期容量は大きいものの、サイクル特性が悪い。逆にｘ
が０．４０以上の電池Ｎおよび電池Ｏでは、サイクル特
性は良好であるが、初期容量が低下する傾向にある。従
って、最適なＣｏの固溶量ｘは、０．１０〜０．３０の
範囲であることがわかる。Example 2 (Batteries I to O) and Comparative Examples 1 and 2
FIG. 3 shows the results of the initial capacity and cycle life of the batteries (Battery P and Battery Q). Regarding the solid solution amount of Co, x
The batteries K to M of 0.10 to 0.30 show good characteristics, and the batteries I and J of x of 0.05 or less are
The initial capacity is large, but the cycle characteristics are poor. Conversely x
In batteries N and O having a value of 0.40 or more, the cycle characteristics are good, but the initial capacity tends to decrease. Therefore, it can be seen that the optimum amount of solid solution x of Co is in the range of 0.10 to 0.30.
【００３８】また、正極活物質を従来法によって合成し
た電池Ｐは、初期容量が小さく、サイクル特性も悪い。
これは、完全にＣｏが固溶した単一相の複合酸化物が生
成していないために容量が低下したものと考えられ、ま
た充放電時の相変化により生じた結晶構造のわずかな歪
のためにサイクルによる可逆性が劣るものと思われる。
従って、高容量でサイクル特性に優れたリチウム二次電
池を得るためには、共沈法によって合成された正極活物
質を用いることが好ましい。Further, the battery P in which the positive electrode active material is synthesized by the conventional method has a small initial capacity and poor cycle characteristics.
It is considered that this is because the capacity was decreased because the single-phase composite oxide in which Co was completely dissolved was not generated, and the slight distortion of the crystal structure caused by the phase change at the time of charge / discharge was observed. Therefore, it seems that reversibility due to cycling is poor.
Therefore, in order to obtain a lithium secondary battery having a high capacity and excellent cycle characteristics, it is preferable to use the positive electrode active material synthesized by the coprecipitation method.
【００３９】次に、負極に人造黒鉛をそのまま使用した
電池Ｑであるが、サイクル特性は良好であるものの、初
期容量が極めて小さい。これは、人造黒鉛は鱗片状の形
状を有することに起因すると考えられる。すなわち、黒
鉛がｃ軸を電極表面と垂直方向に向けて配置され、リチ
ウムのインターカレート／デインタカレートの進行が阻
害されるような電極構造となってしまうためと考えられ
る。このような高率の充放電においては、負極の分極が
大きくなってしまい、結果として容量低下につながる。
このことから、負極としては、黒鉛粒子が比較的ランダ
ムな配向をとるような材料が好ましく、実施例１あるい
は実施例２で使用したメソフェーズ黒鉛や改質人造黒鉛
が最適である。Next, there is a battery Q in which artificial graphite is used as it is for the negative electrode, and although the cycle characteristics are good, the initial capacity is extremely small. It is considered that this is because artificial graphite has a scaly shape. That is, it is considered that the graphite has an electrode structure in which the c-axis is oriented in the direction perpendicular to the electrode surface and the progress of lithium intercalation / deintercalation is hindered. At such a high rate of charge and discharge, the polarization of the negative electrode becomes large, resulting in a decrease in capacity.
From this, a material in which graphite particles have a relatively random orientation is preferable for the negative electrode, and the mesophase graphite or modified artificial graphite used in Example 1 or 2 is most suitable.
【００４０】なお、上記実施例では、電解液の溶媒とし
てＥＣとＥＭＣの混合溶媒を使用したが、他にプロピレ
ンカーボネート、ジエチルカーボネート、ジメチルカー
ボネートなどのカーボネート類、１，２−ジメトキシエ
タン、２−メチルテトラヒドロフランなどのエーテル
類、プロピオン酸メチル、酢酸エチルなどの脂肪族カル
ボン酸エステルなど、従来より公知の溶媒が、単独ある
いは混合溶媒として使用できる。また、電解質として
は、ＬｉＢＦ4、ＬｉＣｌＯ4、ＬｉＣＦ3ＳＯ3など、従
来より公知のものがいずれも使用可能である。上記実施
例および比較例では円筒形電池を使用したが、長尺のシ
ート状の正極および負極をセパレータを挟んで対向させ
て捲回した極板群を用いるものであれば、例えば楕円体
状に捲回して角形の電池ケースに収納した角形電池であ
っても同様な効果が得られる。Although a mixed solvent of EC and EMC was used as the solvent of the electrolytic solution in the above-mentioned examples, other carbonates such as propylene carbonate, diethyl carbonate and dimethyl carbonate, 1,2-dimethoxyethane, 2- Conventionally known solvents such as ethers such as methyltetrahydrofuran and aliphatic carboxylic acid esters such as methyl propionate and ethyl acetate can be used alone or as a mixed solvent. In addition, as the electrolyte, any of conventionally known ones such as LiBF 4 , LiClO 4 , and LiCF 3 SO 3 can be used. Although a cylindrical battery was used in the above-mentioned Examples and Comparative Examples, if a long sheet-shaped positive electrode and negative electrode were used with a group of electrode plates wound facing each other with a separator interposed therebetween, for example, in the form of an ellipsoid. Similar effects can be obtained even with a prismatic battery that is wound and housed in a prismatic battery case.
【００４１】[0041]
【発明の効果】以上のように、本発明によると、高容
量、高エネルギー密度を有し、サイクル特性など電池諸
特性に優れたリチウム二次電池の製造法を提供すること
ができる。As described above, according to the present invention, it is possible to provide a method for producing a lithium secondary battery having a high capacity and a high energy density and excellent in various battery characteristics such as cycle characteristics.
【図１】本発明の一実施例の円筒形リチウム二次電池の
一部を切り欠いた縦断面図である。FIG. 1 is a vertical cross-sectional view in which a cylindrical lithium secondary battery according to an embodiment of the present invention is partially cut away.
【図２】同充電条件に対する初期容量及びサイクル寿命
を示す特性図である。FIG. 2 is a characteristic diagram showing initial capacity and cycle life under the same charging conditions.
【図３】正極活物質（ＬｉＮｉ1-xＣｏxＯ2）中のＣｏ
量に対するリチウム二次電池の初期容量及びサイクル寿
命を示す特性図である。FIG. 3 shows Co in a positive electrode active material (LiNi 1-x Co x O 2 ).
It is a characteristic view which shows the initial capacity and cycle life of a lithium secondary battery with respect to the amount.
１ 電池ケース ２ 封口板 ３ 絶縁パッキング ４ 極板群 ５ 正極リード ６ 負極リード ７ 絶縁リング DESCRIPTION OF SYMBOLS 1 Battery case 2 Sealing plate 3 Insulation packing 4 Electrode group 5 Positive electrode lead 6 Negative electrode lead 7 Insulation ring
フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０１Ｍ 10/44 Ｈ０１Ｍ 10/44 Ａ Continuation of the front page (51) Int.Cl. 6 Identification number Office reference number FI Technical display location H01M 10/44 H01M 10/44 A
Claims (3)
アルカリ溶液を加える共沈法によって合成したＮｉ1-x
Ｃｏx（ＯＨ）2およびリチウム化合物の混合物を熱処理
して、ＬｉＮｉ1-xＣｏxＯ2（但し、０．１０≦ｘ≦
０．３０とする）で表されるリチウム含有複合酸化物を
合成する工程と、前記リチウム含有複合酸化物を活物質
とする正極と、黒鉛化されたメソフェーズ小球体、また
は表面に低結晶性の炭素質層を一部被覆した人造黒鉛粒
子を負極に用いて電池を組み立てる工程と、前記電池
を、前記負極の前記正極と対向する部分の表面電流密度
を０．５ｍＡ／ｃｍ2以下とし、充電電気量を正極比容
量１００ｍＡｈ／ｇ以上、２１０ｍＡｈ／ｇ以下として
充電する工程を含むリチウム二次電池の製造法。1. Ni 1-x synthesized by a coprecipitation method in which an alkaline solution is added to a mixed aqueous solution of a nickel salt and a cobalt salt.
A mixture of Co x (OH) 2 and a lithium compound is heat treated to obtain LiNi 1-x Co x O 2 (where 0.10 ≦ x ≦
0.30)), a positive electrode using the lithium-containing composite oxide as an active material, a graphitized mesophase sphere, or a surface having low crystallinity. A step of assembling a battery using artificial graphite particles partially covered with a carbonaceous layer as a negative electrode, and charging the battery with a surface current density of a portion of the negative electrode facing the positive electrode of 0.5 mA / cm 2 or less. A method for producing a lithium secondary battery, which comprises a step of charging with an electric quantity of positive electrode having a specific capacity of 100 mAh / g or more and 210 mAh / g or less.
ｃｍ2以下である請求項１記載のリチウム二次電池の製
造法。2. The negative electrode surface current density is 0.3 mA /
The method for producing a lithium secondary battery according to claim 1, wherein the method is cm 2 or less.
３．３５オングストローム〜３．３９オングストローム
である請求項１記載のリチウム二次電池の製造法。3. The method for producing a lithium secondary battery according to claim 1, wherein the crystal plane 002 of the graphite has an interplanar spacing of 3.35 Å to 3.39 Å.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8066684A JPH09259928A (en) | 1996-03-22 | 1996-03-22 | Manufacture of secondary lithium battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8066684A JPH09259928A (en) | 1996-03-22 | 1996-03-22 | Manufacture of secondary lithium battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09259928A true JPH09259928A (en) | 1997-10-03 |
Family
ID=13323014
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8066684A Pending JPH09259928A (en) | 1996-03-22 | 1996-03-22 | Manufacture of secondary lithium battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09259928A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005505117A (en) * | 2001-09-28 | 2005-02-17 | レン，シャオピン | Lithium ion secondary battery or battery, and its protection circuit, electronic device, and charging device |
| JP2007087963A (en) * | 2006-11-28 | 2007-04-05 | Hitachi Maxell Ltd | Nonaqueous secondary battery |
| JP2009281916A (en) * | 2008-05-23 | 2009-12-03 | Mitsubishi Electric Corp | Method for testing battery and electrode |
-
1996
- 1996-03-22 JP JP8066684A patent/JPH09259928A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005505117A (en) * | 2001-09-28 | 2005-02-17 | レン，シャオピン | Lithium ion secondary battery or battery, and its protection circuit, electronic device, and charging device |
| JP2007087963A (en) * | 2006-11-28 | 2007-04-05 | Hitachi Maxell Ltd | Nonaqueous secondary battery |
| JP2009281916A (en) * | 2008-05-23 | 2009-12-03 | Mitsubishi Electric Corp | Method for testing battery and electrode |
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