JP3258868B2 - Positive electrode active material and lithium secondary battery using the same - Google Patents
Positive electrode active material and lithium secondary battery using the sameInfo
- Publication number
- JP3258868B2 JP3258868B2 JP21521295A JP21521295A JP3258868B2 JP 3258868 B2 JP3258868 B2 JP 3258868B2 JP 21521295 A JP21521295 A JP 21521295A JP 21521295 A JP21521295 A JP 21521295A JP 3258868 B2 JP3258868 B2 JP 3258868B2
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- JP
- Japan
- Prior art keywords
- positive electrode
- secondary battery
- lithium secondary
- active material
- 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.)
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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
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- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
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
に係わり、詳しくは電池容量の大きいリチウム二次電池
を得ることを目的とした、正極活物質の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery, and more particularly to an improvement in a positive electrode active material for obtaining a lithium secondary battery having a large battery capacity.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】近年、
リチウム二次電池が、水の分解電圧を考慮する必要がな
いために、正極活物質を適宜選定することにより高電圧
化が可能であるなどの理由から、次世代の二次電池とし
て注目されている。2. Description of the Related Art In recent years,
Because lithium secondary batteries do not need to consider the decomposition voltage of water, high voltage can be achieved by appropriately selecting the positive electrode active material. I have.
【０００３】而して、高電圧化のために、ＬｉＣｏ
Ｏ2 、ＬｉＮｉＯ2 等のリチウム・遷移金属複合酸化物
が正極活物質として主に使用されている。[0003] In order to increase the voltage, LiCo
Lithium / transition metal composite oxides such as O 2 and LiNiO 2 are mainly used as positive electrode active materials.
【０００４】しかしながら、リチウム・遷移金属複合酸
化物は重量及び体積当たりの実容量が総じて小さく、こ
のためこれを正極活物質として使用したリチウム二次電
池には、電池容量が小さいという問題がある。[0004] However, the lithium / transition metal composite oxide has a small actual capacity per weight and volume. Therefore, a lithium secondary battery using this as a positive electrode active material has a problem that the battery capacity is small.
【０００５】本発明は、この問題を解決するべくなされ
たものであって、その目的とするところは、高電圧、且
つ高容量のリチウム二次電池を得ることを可能にする新
規なリチウム二次電池用の正極活物質及びそれを使用し
たリチウム二次電池を提供するにある。The present invention has been made to solve this problem, and an object of the present invention is to provide a novel lithium secondary battery capable of obtaining a high-voltage, high-capacity lithium secondary battery. An object of the present invention is to provide a positive electrode active material for a battery and a lithium secondary battery using the same.
【０００６】[0006]
【課題を解決するための手段】上記目的を達成するため
の本発明に係るリチウム二次電池用の正極活物質は、Ｌ
ｉ2xＣａ1-x Ｓｉ2 （０．３＜ｘ≦０．４）及び／又は
Ｌｉ2yＣａ1-y Ｇｅ2（０．５＜ｙ≦０．６）からな
る。In order to achieve the above object, a positive electrode active material for a lithium secondary battery according to the present invention comprises L
It is composed of i 2x Ca 1-x Si 2 (0.3 <x ≦ 0.4) and / or Li 2y Ca 1-y Ge 2 (0.5 <y ≦ 0.6).
【０００７】また、本発明に係るリチウム二次電池（本
発明電池）は、上記のＬｉ2xＣａ1-x Ｓｉ2 （０．３＜
ｘ≦０．４）及び／又はＬｉ2yＣａ1-y Ｇｅ2 （０．５
＜ｙ≦０．６）からなる正極活物質を使用した電池であ
る。Further, the lithium secondary battery (battery of the present invention) according to the present invention includes the above-mentioned Li 2x Ca 1-x Si 2 (0.3 <
x ≦ 0.4) and / or Li 2y Ca 1-y Ge 2 (0.5
<Y ≦ 0.6) using a positive electrode active material.
【０００８】Ｌｉ2xＣａ1-x Ｓｉ2 （０．３＜ｘ≦０．
４）及びＬｉ2yＣａ1-y Ｇｅ2 （０．５＜ｙ≦０．６）
は、ＬｉＣｏＯ2 、ＬｉＮｉＯ2 等のリチウム・遷移金
属複合酸化物に比べて重量及び体積当たりの実容量がと
もに大きい。また、これらは、リチウム・遷移金属複合
酸化物とほぼ同程度の電位（ｖｓＬｉ／Ｌｉ+ ）を有す
る。したがって、これらを正極活物質として使用するこ
とにより、高電圧、且つ高容量のリチウム二次電池を得
ることが可能となる。Li 2x Ca 1-x Si 2 (0.3 <x ≦ 0.
4) and Li 2y Ca 1-y Ge 2 (0.5 <y ≦ 0.6)
Has a larger real capacity per weight and volume than lithium / transition metal composite oxides such as LiCoO 2 and LiNiO 2 . In addition, these have a potential (vsLi / Li + ) substantially equal to that of the lithium / transition metal composite oxide. Therefore, by using these as a positive electrode active material, a lithium secondary battery having a high voltage and a high capacity can be obtained.
【０００９】[0009]
【発明の実施の形態】Ｌｉ2xＣａ1-x Ｓｉ2 （０．３＜
ｘ≦０．４）としては、特にｘ＝０．４のＬｉ0.8 Ｃａ
0.6 Ｓｉ2 が実容量が最も大きいので好ましい。また、
Ｌｉ2yＣａ1-y Ｇｅ2 （０．５＜ｙ≦０．６）として
は、特にｙ＝０．６のＬｉ1.2 Ｃａ0.4Ｇｅ2 が実容量
が最も大きいので好ましい。Ｌｉ2xＣａ1-x Ｓｉ
2 （０．３＜ｘ≦０．４）とＬｉ2yＣａ1-y Ｇｅ
2 （０．５＜ｙ≦０．６）とは、いずれか一方のみを用
いてもよく、必要に応じて両者を併用してもよい。Ｌｉ
2xＣａ1-x Ｓｉ2 （０．３＜ｘ≦０．４）及びＬｉ2yＣ
ａ1-y Ｇｅ2 （０．５＜ｙ≦０．６）は、例えば次のよ
うにして作製することができる。DETAILED DESCRIPTION OF THE INVENTION Li 2x Ca 1-x Si 2 (0.3 <
x ≦ 0.4), in particular, Li 0.8 Ca with x = 0.4
0.6 Si 2 is preferable since the actual capacity is the largest. Also,
As Li 2y Ca 1-y Ge 2 (0.5 <y ≦ 0.6), Li 1.2 Ca 0.4 Ge 2 with y = 0.6 is particularly preferable since the actual capacity is the largest. Li 2x Ca 1-x Si
2 (0.3 <x ≦ 0.4) and Li 2y Ca 1-y Ge
2 (0.5 <y ≦ 0.6), either one of them may be used, or both may be used as needed. Li
2x Ca 1-x Si 2 (0.3 <x ≦ 0.4) and Li 2y C
a 1-y Ge 2 (0.5 <y ≦ 0.6) can be produced, for example, as follows.
【００１０】すなわち、先ず、過塩素酸アンモニウムの
アセトニトリル溶液を電解液とし、ＳＣＥ（Saturated
Calomel Electrode)電極を対極として、ＣａＳｉ2 又は
ＣａＧｅ2 を定電位電解酸化する。この第１の操作によ
り、ＣａＳｉ2 又はＣａＧｅ2 からＣａの一部（ｘモル
又はｙモル）が脱離してＣａ1-x Ｓｉ2 又はＣａ1-yＧ
ｅ2 が得られる。定電位電解酸化時のＣａＳｉ2 又はＣ
ａＧｅ2 に印加する電位が１Ｖ（ｖｓＳＣＥ電極電位）
を越えると電解液が分解するので、１Ｖが限度である。
次に、過塩素酸リチウムのプロピレンカーボネート溶液
を電解液とし、Ｌｉ極を対極として、Ｃａ1-x Ｓｉ2 又
はＣａ1-y Ｇｅ2 を定電位電解還元する。この第２の操
作により、原子価２価のＣａがｘモル又はｙモル脱離し
て生じた格子欠陥に原子価１価のＬｉが２ｘモル又は２
ｙモル挿入されて、Ｌｉ2xＣａ1-x Ｓｉ2 （０．３＜ｘ
≦０．４）又はＬｉ2yＣａ1-y Ｇｅ2 （０．５＜ｙ≦
０．６）が得られる。That is, first, an acetonitrile solution of ammonium perchlorate is used as an electrolyte, and SCE (Saturated
The Calomel Electrode) electrode as a counter electrode, a constant potential electrolysis oxidizing CaSi 2 or CAGE 2. By this first operation, part (x mole or y mole) of Ca is desorbed from CaSi 2 or CaGe 2 and Ca 1-x Si 2 or Ca 1-y G
e 2 is obtained. CaSi 2 or C during constant potential electrolytic oxidation
potential applied to the AGE 2 is 1V (vs SCE electrode potential)
If it exceeds 1, the electrolytic solution is decomposed, so that 1 V is the limit.
Next, Ca 1-x Si 2 or Ca 1-y Ge 2 is subjected to constant potential electrolytic reduction using a propylene carbonate solution of lithium perchlorate as an electrolyte and a Li electrode as a counter electrode. As a result of this second operation, 2 x mol or 2 x
y 2 mol of Li 2x Ca 1-x Si 2 (0.3 <x
≦ 0.4) or Li 2y Ca 1-y Ge 2 (0.5 <y ≦
0.6) is obtained.
【００１１】ｘ及びｙが、それぞれ０．３より大及び
０．５より大に規制されるのは、ｘが０．３以下のＬｉ
2xＣａ1-x Ｓｉ2 及びｙが０．５以下のＬｉ2yＣａ1-y
Ｇｅ2では、従来のリチウム・遷移金属複合酸化物に比
べて実容量が同程度か、若しくは小さくなるからであ
る。また、ｘ及びｙが、それぞれ０．４以下及び０．６
以下に規制されるのは、ｘが０．４より大のＬｉ2xＣａ
1-x Ｓｉ2 及びｙが０．６より大のＬｉ2yＣａ1-y Ｇｅ
2 が実際には得られないからである。これらは、理論上
は上記第１の操作に於ける定電位電解酸化時の電圧を高
くすれば得られる筈であるが、そのようにすると電解液
が分解してしまうため、実際上は得られないのである。The reason that x and y are regulated to be larger than 0.3 and larger than 0.5, respectively, is that x is 0.3 or less.
2x Ca 1-x Si 2 and Li 2y Ca 1-y with y of 0.5 or less
This is because the actual capacity of Ge 2 is equal to or smaller than that of the conventional lithium / transition metal composite oxide. Also, x and y are 0.4 or less and 0.6, respectively.
Regulated below are those for Li 2x Ca with x greater than 0.4.
Li 2y Ca 1-y Ge with 1-x Si 2 and y greater than 0.6
2 is not actually obtained. These should be obtained theoretically by increasing the voltage during the constant potential electrolytic oxidation in the first operation. However, in such a case, the electrolytic solution is decomposed, and therefore, it is actually obtained. There is no.
【００１２】本発明に係る正極活物質は、ＬｉＣｏ
Ｏ2 、ＬｉＮｉＯ2 等の従来のリチウム・遷移金属複合
酸化物に比べて重量及び体積当たりの理論容量（ｍＡｈ
／ｇ）は小さい。しかし、本発明に係る正極活物質は、
上記第２の操作によりＣａ1-x Ｓｉ2 又はＣａ1-y Ｇｅ
2 にリチウムを電気化学的に挿入して作製したものであ
るので、挿入されたリチウムの１００％が充放電に与か
る。すなわち、理論容量と実容量が一致する。これに対
して、原材料の混合物を焼成することにより作製される
リチウム・遷移金属複合酸化物は、含有せるリチウムの
一部が充放電に与かるだけである。このため、本発明に
係る正極活物質は、従来のリチウム・遷移金属複合酸化
物に比べて重量及び体積当たりの実容量（ｍＡｈ／ｇ）
が大きいのである。参考までに、Ｌｉ0.8 Ｃａ0.6 Ｓｉ
2 、Ｌｉ1.2 Ｃａ0.4 Ｇｅ2 、ＬｉＣｏＯ2 及びＬｉＮ
ｉＯ2 の重量当たりの理論容量（ｍＡｈ／ｇ）及び重量
当たりの実容量（ｍＡｈ／ｇ）を表１に示す。実容量は
２００ｍＡで４．２Ｖ（ｖｓＬｉ／Ｌｉ+ ）まで充電し
た後、２．８Ｖ（ｖｓＬｉ／Ｌｉ+ ）まで放電したとき
の値である。The cathode active material according to the present invention is LiCo
Theoretical capacity per unit weight and volume (mAh) compared to conventional lithium / transition metal composite oxides such as O 2 and LiNiO 2
/ G) is small. However, the positive electrode active material according to the present invention,
By the above second operation, Ca 1-x Si 2 or Ca 1-y Ge
Since lithium is electrochemically inserted into 2 , 100% of the inserted lithium is charged and discharged. That is, the theoretical capacity and the actual capacity match. On the other hand, in the lithium-transition metal composite oxide produced by baking the mixture of the raw materials, only a part of the contained lithium affects charging and discharging. For this reason, the positive electrode active material according to the present invention has a real capacity per weight and volume (mAh / g) that is higher than that of the conventional lithium / transition metal composite oxide.
Is big. For reference, Li 0.8 Ca 0.6 Si
2 , Li 1.2 Ca 0.4 Ge 2 , LiCoO 2 and LiN
Table 1 shows the theoretical capacity per unit weight (mAh / g) and the actual capacity per unit weight (mAh / g) of iO 2 . The actual capacity is a value obtained when the battery is charged to 4.2 V (vsLi / Li + ) at 200 mA and then discharged to 2.8 V (vsLi / Li + ).
【００１３】[0013]
【表１】 [Table 1]
【００１４】本発明電池の負極材料としては、電気化学
的にリチウムイオンを吸蔵及び放出することが可能な黒
鉛、コークス等の炭素材料及び充電時にリチウムが析出
し放電時にリチウムが溶解するところの金属リチウムが
例示される。樹枝状の電析リチウムの成長に起因する内
部短絡の虞れがない点で、炭素材料が好ましく、高容量
化の点で、炭素材料の中でも黒鉛が特に好ましい。As the negative electrode material of the battery of the present invention, a carbon material such as graphite and coke capable of occluding and releasing lithium ions electrochemically and a metal in which lithium precipitates during charging and dissolves during discharging. Lithium is exemplified. A carbon material is preferred in that there is no risk of internal short-circuiting due to the growth of dendritic lithium, and graphite is particularly preferred among carbon materials in terms of increasing capacity.
【００１５】リチウムを負極活物質とする本発明電池で
は、リチウムが水と極めて反応し易い物質であるため、
アルカリ電解液は使用し得ず、水を含まない非水電解液
が使用される。非水電解液としては、例えばエチレンカ
ーボネート、ビニレンカーボネート、プロピレンカーボ
ネート等の高誘電率溶媒に、又は、これらの高誘電率溶
媒とジエチルカーボネート、ジメチルカーボネート、
１，２−ジメトキシエタン、１，２−ジエトキシエタ
ン、エトキシメトキシエタン等の低沸点溶媒との混合溶
媒に、ＬｉＰＦ6 、ＬｉＢＦ4 等の溶質（電解質）を溶
かした溶液を使用することができる。なお、このような
液体電解質の外、液漏れの無いポジションフリーの電池
を得るために、固体電解質又はゲル状電解質（擬似固体
電解質）を使用することもできる。In the battery of the present invention in which lithium is used as a negative electrode active material, since lithium is a material which is very easily reacted with water,
An alkaline electrolyte cannot be used, and a non-aqueous electrolyte containing no water is used. As the non-aqueous electrolyte, for example, ethylene carbonate, vinylene carbonate, a high dielectric constant solvent such as propylene carbonate, or these high dielectric constant solvents and diethyl carbonate, dimethyl carbonate,
A solution in which a solute (electrolyte) such as LiPF 6 or LiBF 4 is dissolved in a mixed solvent with a low boiling point solvent such as 1,2-dimethoxyethane, 1,2-diethoxyethane, and ethoxymethoxyethane can be used. . In addition to such a liquid electrolyte, a solid electrolyte or a gel electrolyte (pseudo solid electrolyte) can also be used to obtain a position-free battery with no liquid leakage.
【００１６】[0016]
【実施例】以下、本発明を実施例に基づいてさらに詳細
に説明するが、本発明は下記実施例に何ら限定されるも
のではなく、その要旨を変更しない範囲において適宜変
更して実施することが可能なものである。EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention may be practiced by appropriately changing the gist of the invention. Is possible.
【００１７】（実施例１） 〔正極の作製〕酸化カルシウム（ＣａＯ）と珪素（Ｓ
ｉ）とをモル比３：５で混合し、炭酸ガス雰囲気下にて
１０００°Ｃで２時間焼成して、ＣａＳｉ2 を得た。こ
のＣａＳｉ2 を、過塩素酸アンモニウムの１Ｍ（モル／
リットル）アセトニトリル溶液を電解液とし、ＳＣＥ
（Saturated Calomel Electrode)電極を対極として、１
Ｖ（ｖｓＳＣＥ電極電位）で２時間定電位電解酸化して
４０％のＣａを脱離させて、Ｃａ0.6 Ｓｉ2 を得た。次
に、このＣａ0.6 Ｓｉ2 を、過塩素酸リチウムの１Ｍプ
ロピレンカーボネート溶液を電解液とし、Ｌｉ極を対極
として、４．２Ｖ（ｖｓＬｉ／Ｌｉ+ ）で２時間定電位
電解還元してＬｉを挿入し、Ｌｉ0.8 Ｃａ0.6Ｓｉ
2 （比重：２．８）を得た。(Example 1) [Preparation of positive electrode] Calcium oxide (CaO) and silicon (S
i) was mixed at a molar ratio of 3: 5, and calcined at 1000 ° C. for 2 hours in a carbon dioxide atmosphere to obtain CaSi 2 . The CaSi 2 was converted to 1 M (mol / mol) of ammonium perchlorate.
Liter) using acetonitrile solution as electrolyte, SCE
(Saturated Calomel Electrode)
V (vs SCE electrode potential) was subjected to constant potential electrolytic oxidation for 2 hours to desorb 40% of Ca to obtain Ca 0.6 Si 2 . Next, this Ca 0.6 Si 2 was subjected to a constant potential electrolytic reduction at 4.2 V (vs Li / Li + ) for 2 hours at 4.2 V (vs Li / Li + ) using a 1 M propylene carbonate solution of lithium perchlorate as an electrolyte and a Li electrode as a counter electrode. Insert Li 0.8 Ca 0.6 Si
2 (specific gravity: 2.8) was obtained.
【００１８】このＬｉ0.8 Ｃａ0.6 Ｓｉ2 （粉末）と、
導電剤としてのアセチレンブラックと、結着剤としての
ポリフッ化ビニリデンとを、重量比９０：６：４で混合
し、これにＮＭＰ（Ｎ−メチル−２−ピロリドン）を加
えて混練してスラリーを調製し、このスラリーを集電体
としてのアルミニウム箔の両面に塗布し、６０°Ｃで２
時間真空乾燥して、正極を作製した。The Li 0.8 Ca 0.6 Si 2 (powder),
Acetylene black as a conductive agent and polyvinylidene fluoride as a binder were mixed at a weight ratio of 90: 6: 4, NMP (N-methyl-2-pyrrolidone) was added thereto, and the mixture was kneaded to form a slurry. This slurry was applied to both sides of an aluminum foil as a current collector,
After vacuum drying for a time, a positive electrode was prepared.
【００１９】〔負極の作製〕平均粒径１２μｍの黒鉛粉
末（関西熱化学社製、商品コード「ＮＧ１２」）４９５
重量部と、結着剤としてのポリイミド５重量部をＮＭＰ
１２５０重量部に溶かした結着剤溶液１２５５重量部と
を混練してスラリーを調製し、このスラリーを集電体と
しての銅箔の両面に塗布し、６０°Ｃで２時間真空乾燥
して、負極を作製した。[Preparation of Negative Electrode] 495 graphite powder having an average particle diameter of 12 μm (manufactured by Kansai Thermochemical Co., Ltd., product code “NG12”) 495
Parts by weight and 5 parts by weight of polyimide as a binder
A slurry was prepared by kneading 1255 parts by weight of a binder solution dissolved in 1250 parts by weight, and this slurry was applied to both surfaces of a copper foil as a current collector, and vacuum-dried at 60 ° C. for 2 hours. A negative electrode was manufactured.
【００２０】〔非水電解液の調製〕エチレンカーボネー
トとジエチルカーボネートとの体積比１：１の混合溶媒
に、ヘキサフルオロ燐酸リチウム（ＬｉＰＦ6 ）を１モ
ル／リットル溶かして非水電解液を調製した。[Preparation of Nonaqueous Electrolyte] A nonaqueous electrolyte was prepared by dissolving 1 mol / liter of lithium hexafluorophosphate (LiPF 6 ) in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1. .
【００２１】〔電池の組立〕以上の正極、負極、非水電
解液、及び、セパレータとしてのポリエチレン製の微多
孔膜などを用いて、ＡＡサイズのリチウム二次電池（本
発明電池）Ａ１を組み立てた。なお、この電池は、正極
の容量を負極の容量に比べて小さくして、電池容量が正
極の容量に支配されるようにした電池である。[Assembly of Battery] An AA size lithium secondary battery (battery of the present invention) A1 is assembled using the above-described positive electrode, negative electrode, non-aqueous electrolyte, polyethylene microporous membrane as a separator, and the like. Was. In this battery, the capacity of the positive electrode is smaller than the capacity of the negative electrode, so that the battery capacity is controlled by the capacity of the positive electrode.
【００２２】図１は、組み立てたリチウム二次電池を模
式的に示す断面図であり、図示のリチウム二次電池Ａ１
は、正極１、負極２、これら両電極１，２を互いに離間
するセパレータ３、正極リード４、負極リード５、正極
蓋６、負極缶７などからなる。FIG. 1 is a cross-sectional view schematically showing the assembled lithium secondary battery.
Comprises a positive electrode 1, a negative electrode 2, a separator 3 for separating the electrodes 1 and 2 from each other, a positive electrode lead 4, a negative electrode lead 5, a positive electrode cover 6, a negative electrode can 7, and the like.
【００２３】正極１及び負極２は、セパレータ３を間に
介して渦巻き状に巻き取られ、負極缶（電池缶）７内に
収納されており、正極１は正極リード４を介して正極蓋
６に、また負極２は負極リード５を介して負極缶７に接
続され、電池Ａ１の内部に生じた化学エネルギーを両端
子から電気エネルギーとして外部へ取り出し得るように
なっている。なお、セパレータ３には、封口前に非水電
解液が注入されている。The positive electrode 1 and the negative electrode 2 are spirally wound with a separator 3 interposed therebetween and housed in a negative electrode can (battery can) 7. In addition, the negative electrode 2 is connected to a negative electrode can 7 via a negative electrode lead 5 so that chemical energy generated inside the battery A1 can be taken out from both terminals as electric energy. The separator 3 is filled with a non-aqueous electrolyte before sealing.
【００２４】（実施例２）酸化カルシウム（ＣａＯ）と
ゲルマニウム（Ｇｅ）とをモル比３：５で混合し、炭酸
ガス雰囲気下にて１０００°Ｃで２時間焼成して、Ｃａ
Ｇｅ2 を得た。このＣａＧｅ2 を、過塩素酸アンモニウ
ムの１Ｍアセトニトリル溶液を電解液とし、ＳＣＥ（Sa
turated Calomel Electrode)電極を対極として、１Ｖ
（ｖｓＳＣＥ電極電位）で２時間定電位電解酸化して６
０％のＣａを脱離させて、Ｃａ0.4 Ｇｅ2 を得た。次
に、このＣａ0.4 Ｇｅ2 を、過塩素酸リチウムの１Ｍプ
ロピレンカーボネート溶液を電解液とし、Ｌｉ極を対極
として、４．２Ｖ（ｖｓＬｉ／Ｌｉ+ ）で２時間定電位
電解還元してＬｉを挿入し、Ｌｉ1.2 Ｃａ0.4 Ｇｅ
2 （比重：２．９）を得た。Example 2 Calcium oxide (CaO) and germanium (Ge) were mixed at a molar ratio of 3: 5, and calcined at 1000 ° C. for 2 hours in a carbon dioxide atmosphere to obtain a mixture of Ca and Ca.
Ge 2 was obtained. This CaGe 2 was converted to SCE (Sa) by using a 1 M solution of ammonium perchlorate in acetonitrile as an electrolyte.
turated Calomel Electrode) 1V with electrode as counter electrode
(Vs SCE electrode potential) at constant potential electrolytic oxidation for 2 hours
0% of Ca was desorbed to obtain Ca 0.4 Ge 2 . Next, this Ca 0.4 Ge 2 was subjected to constant potential electrolytic reduction at 4.2 V (vs Li / Li + ) for 2 hours at 4.2 V (vs Li / Li + ) using a 1 M propylene carbonate solution of lithium perchlorate as an electrolyte and a Li electrode as a counter electrode. Insert Li 1.2 Ca 0.4 Ge
2 (specific gravity: 2.9) was obtained.
【００２５】このＬｉ0.8 Ｃａ0.6 Ｓｉ2 （粉末）と、
導電剤としてのアセチレンブラックと、結着剤としての
ポリフッ化ビニリデンとを、重量比９０：６：４で混合
し、これにＮＭＰ（Ｎ−メチル−２−ピロリドン）を加
えて混練してスラリーを調製し、このスラリーを集電体
としてのアルミニウム箔の両面に塗布し、６０°Ｃで２
時間真空乾燥して、正極を作製した。この正極を使用し
たこと以外は実施例１と同様にして、ＡＡサイズのリチ
ウム二次電池（本発明電池）Ａ２を組み立てた。This Li 0.8 Ca 0.6 Si 2 (powder),
Acetylene black as a conductive agent and polyvinylidene fluoride as a binder were mixed at a weight ratio of 90: 6: 4, NMP (N-methyl-2-pyrrolidone) was added thereto, and the mixture was kneaded to form a slurry. This slurry was applied to both sides of an aluminum foil as a current collector,
After vacuum drying for a time, a positive electrode was prepared. An AA-size lithium secondary battery (battery of the present invention) A2 was assembled in the same manner as in Example 1 except that this positive electrode was used.
【００２６】（比較例）水酸化リチウム（ＬｉＯＨ）と
水酸化コバルト（Ｃｏ（ＯＨ）2 ）とを乳鉢中にてモル
比１：１で混合し、乾燥空気雰囲気下にて７５０°Ｃで
２０時間焼成して、ＬｉＣｏＯ2 （比重：３．０）を得
た。このＬｉＣｏＯ2 （粉末）と、導電剤としてのアセ
チレンブラックと、結着剤としてのポリフッ化ビニリデ
ンとを、重量比９０：６：４で混合し、これにＮＭＰ
（Ｎ−メチル−２−ピロリドン）を加えて混練してスラ
リーを調製し、このスラリーを集電体としてのアルミニ
ウム箔の両面に塗布し、６０°Ｃで２時間真空乾燥し
て、正極を作製した。この正極を使用したこと以外は実
施例１と同様にして、ＡＡサイズのリチウム二次電池
（比較電池）Ｂを組み立てた。Comparative Example Lithium hydroxide (LiOH) and cobalt hydroxide (Co (OH) 2 ) were mixed in a mortar at a molar ratio of 1: 1 and dried at 750 ° C. in a dry air atmosphere. After calcination for an hour, LiCoO 2 (specific gravity: 3.0) was obtained. This LiCoO 2 (powder), acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a weight ratio of 90: 6: 4, and NMP was added thereto.
(N-methyl-2-pyrrolidone) was added and kneaded to prepare a slurry, and this slurry was applied to both sides of an aluminum foil as a current collector, and vacuum-dried at 60 ° C. for 2 hours to produce a positive electrode. did. An AA-size lithium secondary battery (comparative battery) B was assembled in the same manner as in Example 1 except that this positive electrode was used.
【００２７】なお、上記の実施例１，２及び比較例で
は、正極活物質の重量を互いに等しくして正極を作製し
た。In Examples 1 and 2 and Comparative Example, positive electrodes were manufactured with the same weight of the positive electrode active material.
【００２８】〔各電池の放電特性〕各電池の放電特性
を、２００ｍＡで４．２Ｖまで充電した後、２００ｍＡ
で２．８Ｖまで放電して調べた。結果を図２に示す。図
２は、各電池の放電特性を、縦軸に電池電圧（Ｖ）を、
横軸に放電容量（ｍＡｈ）を、それぞれとって示したグ
ラフである。[Discharge characteristics of each battery] The discharge characteristics of each battery were measured at 200 mA to 4.2 V and then charged at 200 mA.
And discharged to 2.8V. The results are shown in FIG. FIG. 2 shows the discharge characteristics of each battery, the vertical axis shows the battery voltage (V),
It is a graph which showed the discharge capacity (mAh) on the horizontal axis.
【００２９】図２に示すように、本発明電池Ａ１，Ａ２
は、比較電池Ｂに比べて、格段大きな放電容量を有して
いる。また、放電電圧に関しても、本発明電池Ａ１，Ａ
２は、比較電池Ｂに比べて、若干高い。このことから、
本発明に係るＬｉ2xＣａ1-xＳｉ2 （０．３＜ｘ≦０．
４）及び／又はＬｉ2yＣａ1-y Ｇｅ2 （０．５＜ｙ≦
０．６）からなる正極活物質を使用することにより、高
電圧、且つ高容量のリチウム二次電池が得られることが
分かる。As shown in FIG. 2, the batteries A1 and A2 of the present invention
Has a significantly larger discharge capacity than the comparative battery B. Also, regarding the discharge voltage, the batteries A1, A
2 is slightly higher than the comparative battery B. From this,
Li 2x Ca 1-x Si 2 (0.3 <x ≦ 0.
4) and / or Li 2y Ca 1-y Ge 2 (0.5 <y ≦
It can be seen that the use of the positive electrode active material composed of 0.6) enables a high-voltage, high-capacity lithium secondary battery to be obtained.
【００３０】上記実施例１及び２では、Ｌｉ2xＣａ1-x
Ｓｉ2 （０．３＜ｘ≦０．４）及びＬｉ2yＣａ1-y Ｇｅ
2 （０．５＜ｙ≦０．６）の中で最も容量の大きいＬｉ
0.8Ｃａ0.6 Ｓｉ2 又はＬｉ1.2 Ｃａ0.4 Ｇｅ2 を正極
活物質として使用したが、他の正極活物質〔Ｌｉ2xＣａ
1-x Ｓｉ2 （０．３＜ｘ＜０．４）及びＬｉ2yＣａ1-y
Ｇｅ2 （０．５＜ｙ＜０．６）〕を用いた場合にも、従
来のリチウム・遷移金属複合酸化物を正極活物質に使用
したリチウム二次電池に比べて高容量の電池を得ること
ができることを確認している。In Examples 1 and 2, Li 2x Ca 1-x
Si 2 (0.3 <x ≦ 0.4) and Li 2y Ca 1-y Ge
2 Li with the largest capacity among (0.5 <y ≦ 0.6)
Although 0.8 Ca 0.6 Si 2 or Li 1.2 Ca 0.4 Ge 2 was used as the positive electrode active material, other positive electrode active materials [Li 2x Ca 2
1-x Si 2 (0.3 <x <0.4) and Li 2y Ca 1-y
Even when Ge 2 (0.5 <y <0.6)] is used, a battery having a higher capacity can be obtained as compared with a lithium secondary battery using a conventional lithium / transition metal composite oxide as a positive electrode active material. Make sure you can.
【００３１】[0031]
【発明の効果】本発明に係る正極活物質は、重量及び体
積当たりの実容量が従来のリチウム・遷移金属複合酸化
物に比べて大きく、また電位も高い。このため、本発明
に係る正極活物質を使用することにより、高電圧、且つ
高容量のリチウム二次電池を得ることが可能になる。The positive electrode active material according to the present invention has a higher real capacity per weight and volume than a conventional lithium / transition metal composite oxide and a higher potential. Therefore, by using the positive electrode active material according to the present invention, a high-voltage, high-capacity lithium secondary battery can be obtained.
【図１】実施例で組み立てたＡＡサイズのリチウム二次
電池の断面図である。FIG. 1 is a cross-sectional view of an AA size lithium secondary battery assembled in an example.
【図２】本発明電池及び比較電池の放電特性を示したグ
ラフである。FIG. 2 is a graph showing discharge characteristics of a battery of the present invention and a comparative battery.
Ａ１ リチウム二次電池（本発明電池） １ 正極 ２ 負極 ３ セパレータ A1 Lithium secondary battery (battery of the present invention) 1 Positive electrode 2 Negative electrode 3 Separator
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平８−321305（ＪＰ，Ａ) 特開 平６−163080（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01M 4/36 - 4/62 H01M 4/02 - 4/04 H01M 10/40 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-321305 (JP, A) JP-A-6-163080 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H01M 4/36-4/62 H01M 4/02-4/04 H01M 10/40
Claims (5)
４）及び／又はＬｉ2yＣａ1-y Ｇｅ2 （０．５＜ｙ≦
０．６）からなるリチウム二次電池用の正極活物質。(1) Li 2x Ca 1-x Si 2 (0.3 <x ≦ 0.
4) and / or Li 2y Ca 1-y Ge 2 (0.5 <y ≦
0.6). A positive electrode active material for a lithium secondary battery comprising:
1.2 Ｃａ0.4 Ｇｅ2 からなるリチウム二次電池用の正極
活物質。Wherein Li 0.8 Ca 0.6 Si 2 and / or Li
A cathode active material for a lithium secondary battery comprising 1.2 Ca 0.4 Ge 2 .
４）及び／又はＬｉ2yＣａ1-y Ｇｅ2 （０．５＜ｙ≦
０．６）からなる正極活物質が使用されているリチウム
二次電池。3. Li 2x Ca 1-x Si 2 (0.3 <x ≦ 0.
4) and / or Li 2y Ca 1-y Ge 2 (0.5 <y ≦
A lithium secondary battery using the positive electrode active material according to 0.6).
1.2 Ｃａ0.4 Ｇｅ2 からなる正極活物質が使用されてい
るリチウム二次電池。4. Li 0.8 Ca 0.6 Si 2 and / or Li 0.8 Ca 0.6 Si 2
A lithium secondary battery using a positive electrode active material composed of 1.2 Ca 0.4 Ge 2 .
出することが可能な炭素材料が負極のリチウムイオン吸
蔵材として使用されている請求項３又は４記載のリチウ
ム二次電池。5. The lithium secondary battery according to claim 3, wherein a carbon material capable of electrochemically storing and releasing lithium ions is used as the lithium ion storage material of the negative electrode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21521295A JP3258868B2 (en) | 1995-07-31 | 1995-07-31 | Positive electrode active material and lithium secondary battery using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21521295A JP3258868B2 (en) | 1995-07-31 | 1995-07-31 | Positive electrode active material and lithium secondary battery using the same |
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| Publication Number | Publication Date |
|---|---|
| JPH0945329A JPH0945329A (en) | 1997-02-14 |
| JP3258868B2 true JP3258868B2 (en) | 2002-02-18 |
Family
ID=16668560
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21521295A Expired - Fee Related JP3258868B2 (en) | 1995-07-31 | 1995-07-31 | Positive electrode active material and lithium secondary battery using the same |
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| Country | Link |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9475968B2 (en) | 2009-04-03 | 2016-10-25 | Ashland Licensing And Intellectual Property, Llc | Ultraviolet radiation curable pressure sensitive acrylic adhesive |
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1995
- 1995-07-31 JP JP21521295A patent/JP3258868B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9475968B2 (en) | 2009-04-03 | 2016-10-25 | Ashland Licensing And Intellectual Property, Llc | Ultraviolet radiation curable pressure sensitive acrylic adhesive |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0945329A (en) | 1997-02-14 |
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