JP2001110418A - Positive electrode for lithium secondary battery and the lithium secondary battery - Google Patents
Positive electrode for lithium secondary battery and the lithium secondary batteryInfo
- Publication number
- JP2001110418A JP2001110418A JP29079799A JP29079799A JP2001110418A JP 2001110418 A JP2001110418 A JP 2001110418A JP 29079799 A JP29079799 A JP 29079799A JP 29079799 A JP29079799 A JP 29079799A JP 2001110418 A JP2001110418 A JP 2001110418A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- secondary battery
- lithium secondary
- lithium
- activated carbon
- 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
Landscapes
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Carbon And Carbon Compounds (AREA)
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・
離脱現象を利用したリチウム二次電池に関し、それを構
成するリチウム二次電池用正極に関する。TECHNICAL FIELD The present invention relates to a method for storing and storing lithium.
The present invention relates to a lithium secondary battery utilizing a detachment phenomenon, and to a positive electrode for a lithium secondary battery constituting the same.
【０００２】[0002]
【従来の技術】携帯電話、パソコン等の小型化に伴い、
エネルギー密度の高い二次電池が必要とされ、通信機
器、情報関連機器の分野では、リチウム二次電池が広く
普及するに至っている。また、資源問題、環境問題か
ら、自動車の分野でも電気自動車に対する要望が高ま
り，安価であってかつ容量が大きく、サイクル特性が良
好なリチウム二次電池の開発が急がれている。2. Description of the Related Art As mobile phones and personal computers become smaller,
Secondary batteries with high energy density are required, and lithium secondary batteries have come into widespread use in the fields of communication devices and information-related devices. In addition, demands for electric vehicles are increasing in the field of automobiles due to resource problems and environmental problems, and development of lithium secondary batteries that are inexpensive, have large capacities, and have good cycle characteristics is urgently required.
【０００３】現在、リチウム二次電池の正極活物質に
は、４Ｖ級の二次電池を構成できるものとして、層状岩
塩構造のＬｉＣｏＯ2が採用されるに至っている。Ｌｉ
ＣｏＯ2は、合成が容易でかつ取り扱いも比較的容易で
あることに加え、充放電サイクル特性において優れるこ
とから、ＬｉＣｏＯ2を正極活物質に使用する二次電池
が主流となっている。At present, as a positive electrode active material of a lithium secondary battery, LiCoO 2 having a layered rock salt structure has been adopted as a material capable of constituting a 4 V class secondary battery. Li
Since CoO 2 is easy to synthesize and relatively easy to handle and has excellent charge / discharge cycle characteristics, secondary batteries using LiCoO 2 as a positive electrode active material are mainly used.
【０００４】ところが、コバルトは資源量として少な
く、ＬｉＣｏＯ2を正極活物質に使用した二次電池で
は、自動車用電池をにらんだ将来の量産化、大型化に対
応しにくく、また価格的にも極めて高価なものにならざ
るを得ない。そこでコバルトに代えて、比較的資源とし
て豊富でありかつ安価なマンガンを構成元素として含
む、基本組成をＬｉＭｎ2Ｏ4としたスピネル構造のリチ
ウムマンガン複合酸化物を正極活物質に用いる試みがな
されている。[0004] However, cobalt is a scarce resource, and a secondary battery using LiCoO 2 as a positive electrode active material is difficult to cope with future mass production and size enlargement of automobile batteries, and also in terms of price. It must be very expensive. Therefore, instead of cobalt, attempts have been made to use a lithium manganese composite oxide having a spinel structure of LiMn 2 O 4 having a basic composition of LiMn 2 O 4 , which is relatively abundant and inexpensive as a constituent element, as a positive electrode active material. I have.
【０００５】[0005]
【発明が解決しようとする課題】本発明者は、スピネル
構造リチウムマンガン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についての試験の結果より、幅広
い充電状態（ＳＯＣ）領域において高い電位を示す充放
電挙動を呈するとの知見を得た。この知見によれば、ス
ピネル構造リチウムマンガン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においては、放電時には、
大きな電位差に起因して高い出力パワー密度（放電パワ
ー密度）が得られるが、その反面、充電時には、電位差
が小さいため入力パワー密度（充電パワー密度）が低く
なることが明らかになる。SUMMARY OF THE INVENTION The present inventor has found that a high potential in a wide state of charge (SOC) region can be obtained from a result of a test on a lithium secondary battery using a spinel structure lithium manganese composite oxide as a positive electrode active material. It was found that the battery exhibited the charge-discharge behavior shown. According to this finding, in a lithium secondary battery using a spinel-structured lithium manganese composite oxide as a positive electrode active material, during discharge,
Although a high output power density (discharge power density) can be obtained due to the large potential difference, it is clear that the input power density (charge power density) decreases during charging because the potential difference is small.
【０００６】リチウム二次電池を電気自動車用電源に用
いようとする場合、充電パワー密度が小さいことは、大
きな障害となる。電気自動車では減速時のエネルギーを
回生して電源となる電池に充電させるが、この回生エネ
ルギーは大きく、短時間に大電流が電池に供給される場
合、充電パワー密度が小さな電池では、効率よく充電で
きないことになる。したがって、スピネル構造リチウム
マンガン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、このままでは、電気自動車用電源等の大電
流入力用途に適さないものとなる。When a lithium secondary battery is used as a power source for an electric vehicle, a low charging power density is a major obstacle. Electric vehicles regenerate energy during deceleration and charge the battery as a power source.If the regenerative energy is large and a large current is supplied to the battery in a short period of time, a battery with a small charging power density can be charged efficiently. You can't. Therefore, a lithium secondary battery using the spinel-structured lithium manganese composite oxide as a positive electrode active material is not suitable for a large current input application such as a power supply for an electric vehicle.
【０００７】一方、電気自動車用等の回生エネルギー蓄
積デバイスとして、活性炭を電極材料とする電気二重層
キャパシタを用いることが検討されている。電気二重層
キャパシタは、容量は小さいものの、短時間に大電流が
入力された場合であっても、効率よく蓄電することがで
きるという利点を有している。したがって、上記リチウ
ム二次電池と上記キャパシタを組み合わせて、２つのデ
バイスでもって電気自動車用電源を構成することが、上
記リチウム二次電池の充電パワー密度が小さいという欠
点を補う有力な手段となる。On the other hand, as a regenerative energy storage device for electric vehicles and the like, use of an electric double layer capacitor using activated carbon as an electrode material has been studied. Although the electric double layer capacitor has a small capacity, it has an advantage that power can be efficiently stored even when a large current is input in a short time. Therefore, combining the lithium secondary battery and the capacitor to form a power source for an electric vehicle with two devices is an effective means for compensating for the disadvantage that the charging power density of the lithium secondary battery is low.
【０００８】ところが、２つのデバイスで電源を構成し
た場合、部品点数が増加するばかりでなく、電源自体の
重量および体積が増加し、電源としてのエネルギー密度
が減少することにつながり、例えば電気自動車に搭載し
た場合は、その自動車の走行効率を悪いものとしてしま
う。また、２つのデバイスを用いた場合、相互に関連す
る充放電のファクターに応じて電源を適切に制御するた
めには、高度な制御手段を必要とし、電源自体が複雑な
ものとなるという欠点がある。However, when a power supply is composed of two devices, not only the number of components increases, but also the weight and volume of the power supply itself increase, leading to a decrease in energy density as a power supply. If it is installed, the running efficiency of the car will be degraded. In addition, when two devices are used, advanced control means are required to appropriately control the power supply according to the charge / discharge factors related to each other, and the power supply itself becomes complicated. is there.
【０００９】本発明は、安価なスピネル構造リチウムマ
ンガン複合酸化物を正極活物質として用いたリチウム二
次電池において、充電パワー密度が小さいという上記欠
点を解決すべくなされたものであり、簡便な手段によ
り、安価であってかつ充電パワー密度の大きなリチウム
二次電池を構成することのできるリチウム二次電池用正
極を提供することを課題としている。The present invention has been made to solve the above-mentioned drawback of low charging power density in a lithium secondary battery using an inexpensive lithium manganese oxide having a spinel structure as a positive electrode active material. Accordingly, an object of the present invention is to provide a positive electrode for a lithium secondary battery that can be used to form a lithium secondary battery that is inexpensive and has a high charging power density.
【００１０】[0010]
【課題を解決するための手段】本発明のリチウム二次電
池用正極は、スピネル構造リチウムマンガン複合酸化物
と、活性炭とを、活物質として含むことを特徴とする。
つまり、本リチウム二次電池用正極は、従来のリチウム
二次電池の正極としての機能に、活性炭を電極材料とす
る電気二重層キャパシタとしての機能を付加した電極で
ある。The positive electrode for a lithium secondary battery according to the present invention is characterized by containing a spinel-structured lithium manganese composite oxide and activated carbon as active materials.
That is, the present positive electrode for a lithium secondary battery is an electrode obtained by adding a function as an electric double layer capacitor using activated carbon as an electrode material to the function as a positive electrode of a conventional lithium secondary battery.
【００１１】活性炭は、イオンの吸着性に優れ、比表面
積の大きな炭素材料である。電気二重層キャパシタにお
いては、直流電圧を印加することによって電解質が電離
したイオンが活性炭表面に吸着し、その表面に電気二重
層を形成することで充電される。したがって、容量とし
ては小さいものの、リチウムの吸蔵・離脱といった化学
的反応を伴わないことで、極めて急速な充電が可能とな
る。Activated carbon is a carbon material having a high specific surface area and excellent ion adsorption. In an electric double layer capacitor, the ionized ion of the electrolyte is adsorbed on the activated carbon surface by applying a DC voltage, and is charged by forming an electric double layer on the surface. Therefore, although the capacity is small, it is possible to perform extremely rapid charging without involving a chemical reaction such as insertion and extraction of lithium.
【００１２】本正極における充電時の活性炭の挙動は明
確なものとはなっていないが、大電流が入力された場
合、リチウムマンガン複合酸化物中からリチウムが離脱
するのと並行し、その表面に非水電解液中の電離した電
解質のアニオンが一時的に吸着しすると考えられる。そ
してその後は、電気化学的平衡状態に至るまで、リチウ
ムマンガン複合酸化物中からリチウムが離脱するものと
考えられる。あるいは、放電終了時にその表面に電解質
のカチオンつまりリチウムイオンが吸着した状態になっ
ており、充電時に優先してそのリチウムイオンが正極か
ら負極に向かうものと考えられる。つまり、いずれにし
ても活性炭は、本正極に入力する大電流をバッファ的に
吸収し、効率よい充電を担保する作用を示すと推測され
る。Although the behavior of the activated carbon in the positive electrode at the time of charging has not been clarified, when a large current is input, in parallel with the release of lithium from the lithium manganese composite oxide, the surface of It is considered that the anion of the ionized electrolyte in the non-aqueous electrolyte is temporarily adsorbed. Then, it is considered that lithium is released from the lithium-manganese composite oxide until the state of electrochemical equilibrium is reached. Alternatively, it is considered that cations of the electrolyte, that is, lithium ions are adsorbed on the surface at the end of discharge, and the lithium ions preferentially travel from the positive electrode to the negative electrode during charging. That is, in any case, the activated carbon is assumed to exhibit a function of absorbing a large current input to the present positive electrode as a buffer and ensuring efficient charging.
【００１３】本発明の正極では、この活性炭の作用によ
って、リチウムマンガン複合酸化物の充電パワー密度の
不足を補い、本正極を用いたリチウム二次電池は、充電
パワー密度が高く、急速な充電が可能となる。In the positive electrode of the present invention, the action of the activated carbon compensates for the shortage of the charging power density of the lithium manganese composite oxide, and the lithium secondary battery using the positive electrode has a high charging power density and is capable of rapid charging. It becomes possible.
【００１４】なお、リチウム二次電池用正極は、一般
に、活物質間の電子伝導性を確保するために、カーボン
ブラック等の炭素材料からなる導電材を混合して形成さ
れる。本正極において、「活性炭を活物質として」と
は、炭素材料である活性炭に上記導電材としての機能を
期待するのではなく、主として、表面にイオンを吸着さ
せるという上記バッファ的な機能を果たす中心的電極材
料として用いることを意味する。The positive electrode for a lithium secondary battery is generally formed by mixing a conductive material made of a carbon material such as carbon black in order to secure electron conductivity between active materials. In the present positive electrode, “using activated carbon as an active material” does not mean that activated carbon, which is a carbon material, is expected to function as the conductive material, but is mainly a center that performs the buffer-like function of adsorbing ions on the surface. To be used as an active electrode material.
【００１５】[0015]
【発明の実施の形態】以下に、本発明のリチウム二次電
池用正極の実施形態について説明し、次いで、その正極
を用いた本発明のリチウム二次電池の実施形態について
説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a positive electrode for a lithium secondary battery of the present invention will be described, and then, an embodiment of a lithium secondary battery of the present invention using the positive electrode will be described.
【００１６】〈リチウム二次電池用正極〉本発明のリチ
ウム二次電池用正極は、スピネル構造リチウムマンガン
複合酸化物と活性炭とを活物質として含み、一般のリチ
ウム二次電池用正極と同様に、その活物質と、その活物
質の電子伝導性を確保するための導電材と、その活物質
および導電材を結着する結着剤とから構成される。正極
活物質において、スピネル構造リチウムマンガン複合酸
化物は、主たる活物質材料となり、活性炭は、上述した
ように大電流充電時におけるバッファ的な役割を果たす
補助的な活物質材料となる。なお、正極活物質は、この
リチウムマンガン複合酸化物および活性炭の他に、リチ
ウムコバルト複合酸化物、リチウムニッケル複合酸化物
等の既に公知の活物質材料を補佐的に含むものであって
も構わない。<Positive Electrode for Lithium Secondary Battery> The positive electrode for a lithium secondary battery of the present invention contains a spinel-structured lithium manganese composite oxide and activated carbon as active materials. It comprises the active material, a conductive material for ensuring the electronic conductivity of the active material, and a binder for binding the active material and the conductive material. In the positive electrode active material, the spinel-structured lithium manganese composite oxide serves as a main active material, and the activated carbon serves as an auxiliary active material serving as a buffer during large-current charging as described above. Note that, in addition to the lithium manganese composite oxide and the activated carbon, the positive electrode active material may additionally include a known active material such as a lithium cobalt composite oxide and a lithium nickel composite oxide. .
【００１７】主たる活物質材料であるスピネル構造リチ
ウムマンガン複合酸化物は、主たる構成元素として安価
なマンガンを含有することで、４Ｖ級のリチウム二次電
池を極めて安価に構成できる活物質材料であることか
ら、本正極において採用した。スピネル構造リチウム複
合酸化物は、組成式ＬｉＭｎ2Ｏ4で表される化学量論組
成のものを用いることができる。また、正極活物質とし
ての特性を改善するために、結晶構造におけるＭｎサイ
ト、Ｌｉサイトを他の元素で置換したものをも用いるこ
とができる。The lithium manganese oxide having a spinel structure, which is a main active material, contains an inexpensive manganese as a main constituent element, so that a 4V-class lithium secondary battery can be formed at very low cost. From this, it was adopted in the present positive electrode. The stoichiometric composition represented by the composition formula LiMn 2 O 4 can be used as the spinel-structured lithium composite oxide. Further, in order to improve the characteristics as a positive electrode active material, a material in which a Mn site and a Li site in a crystal structure are replaced with another element can be used.
【００１８】種々の組成をもつスピネル構造リチウムマ
ンガン複合酸化物のなかでも、サイクル特性を良好なも
のとするために、組成式Ｌｉ1+xＭyＭｎ2-x-yＯ4-z（Ｍ
はＴｉ、Ｖ、Ｃｒ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎ、Ｃｕ、
Ｗ、Ｍｇ、Ａｌのうちの１種以上；０≦ｘ＜０．２；０
≦ｙ＜０．５；０≦ｚ＜０．２）で表されるものを用い
ることが望ましい。ｘ≧０．２の場合やｙ≧０．５の場
合には、固相法による製造が困難であり、不純物相が生
成して結晶性を低下させる可能性があるからであり、ま
た、ｚ≧０．２では、スピネル構造となり得ないおそれ
があることから上記組成範囲のものが望ましいとしてい
る。[0018] Among the spinel structure lithium manganese composite oxide having various compositions, in order to the cycle characteristics favorable, the composition formula Li 1 + x M y Mn 2 -xy O 4-z (M
Are Ti, V, Cr, Fe, Co, Ni, Zn, Cu,
At least one of W, Mg, and Al; 0 ≦ x <0.2; 0
≦ y <0.5; 0 ≦ z <0.2). If x ≧ 0.2 or y ≧ 0.5, it is difficult to manufacture by a solid phase method, and there is a possibility that an impurity phase is generated and crystallinity is reduced. If ≧ 0.2, there is a possibility that a spinel structure cannot be formed, so that a composition within the above-described range is desirable.
【００１９】スピネル構造リチウムマンガン複合酸化物
は、その製造方法を特に限定するものでなく、固相反応
法等の従来から公知の方法を用いて製造すればよい。例
えば、上記組成式Ｌｉ1+xＭyＭｎ2-x-yＯ4-zで表される
ものを製造する場合、Ｌｉ2ＣＯ3、Ｌｉ（ＯＨ）等のリ
チウム化合物と、ＭｎＯ2、Ｍｎ3Ｏ4等のマンガン化合
物と、Ａｌ2Ｏ3、ＡｌＮ等のアルミニウム化合物とを、
得ようとするリチウムマンガン複合酸化物の組成に応じ
た所定量にそれぞれ秤量した後、ボールミル等により混
合し、この混合物を、大気中あるいは酸素気流中で、６
００〜９５０℃の温度下、８〜２４時間焼成することに
よって合成できる。The method for producing the spinel-structured lithium manganese composite oxide is not particularly limited, and it may be produced by a conventionally known method such as a solid phase reaction method. For example, when manufacturing those represented by the above composition formula Li 1 + x M y Mn 2 -xy O 4-z, and Li 2 CO 3, lithium compounds such as Li (OH), MnO 2, Mn 3 O A manganese compound such as 4 and an aluminum compound such as Al 2 O 3 and AlN;
After each is weighed to a predetermined amount according to the composition of the lithium-manganese composite oxide to be obtained, the mixture is mixed by a ball mill or the like, and the mixture is mixed in air or in an oxygen stream.
It can be synthesized by firing at a temperature of 00 to 950 ° C. for 8 to 24 hours.
【００２０】補助的な活物質として用いる活性炭は、そ
の種類を特に限定するものではない。フェノール系、ヤ
シがら系、コークス系等、通常電気二重層キャパシタに
用いることのできるものであれば、用いることができ
る。活性炭では、その吸着力を示す目安として比表面積
を用いる。本発明の正極における活性炭は、ＢＥＴ比表
面積において、３００〜３０００ｍ2／ｇのものを用い
るのが望ましい。３００ｍ2／ｇ未満のものはイオンの
吸着量が少なすぎ、また、３０００ｍ2／ｇを超えるも
のは、活性炭中の細孔容積が増大し、正極における見か
けの密度が低下し、単位体積あたりのイオン吸着量が減
少し過ぎるからである。The type of activated carbon used as an auxiliary active material is not particularly limited. Any phenol type, coconut type, coke type, or the like that can be generally used for an electric double layer capacitor can be used. Activated carbon uses its specific surface area as a measure of its adsorptive power. The activated carbon in the positive electrode of the present invention preferably has a BET specific surface area of 300 to 3000 m 2 / g. If the amount is less than 300 m 2 / g, the amount of adsorbed ions is too small. If the amount exceeds 3000 m 2 / g, the pore volume in the activated carbon increases, the apparent density in the positive electrode decreases, and the volume per unit volume decreases. This is because the amount of ion adsorption is excessively reduced.
【００２１】上記リチウムマンガン複合酸化物と上記活
性炭とを活物質として用いる場合、両者とも粉状体とし
て混合する。本発明の正極は、上述したように、その目
的がリチウムマンガン複合酸化物のパワー密度の不足を
活性炭によって補助するということにあることから、両
者の混合する割合、つまり活物質中における両者の混合
比について、望ましい範囲が存在する。この望ましい範
囲は、スピネル構造リチウムマンガン複合酸化物と活性
炭との合計を１００ｗｔ％とした場合に、活性炭を５ｗ
ｔ％以上１５ｗｔ％以下とする範囲である。活性炭が５
ｗｔ％未満の場合は、正極の充電パワー密度の向上効果
があまり期待できす、また、１５ｗｔ％を超える場合に
は、正極容量低下が懸念され、また、通常量の結着剤に
よっては充分な結着力が得られずシート電極化が困難と
なるからである。When the lithium manganese composite oxide and the activated carbon are used as active materials, both are mixed as a powder. As described above, since the purpose of the positive electrode of the present invention is to assist the lack of power density of the lithium manganese composite oxide with activated carbon, the mixing ratio of the two, that is, the mixing of both in the active material, There is a desirable range for the ratio. This desirable range is as follows: when the total of the spinel structure lithium manganese composite oxide and the activated carbon is 100 wt%, the activated carbon is 5 watts.
The range is from t% to 15 wt%. 5 activated carbon
When the content is less than 15 wt%, the effect of improving the charging power density of the positive electrode can be expected to be very small. When the content exceeds 15 wt%, there is a concern that the capacity of the positive electrode may be reduced. This is because a binding force cannot be obtained and it is difficult to form a sheet electrode.
【００２２】本発明の正極は、正極活物質を除きその構
成は通常のリチウム二次電池用正極の構成に従えばよ
く、上記活物質と、その活物質の電子伝導性を確保する
ための導電材と、その活物質および導電材を結着する結
着剤とから構成される。また、その製造方法も通常のリ
チウム二次電池用正極の製造方法に従えばよく、その製
造方法を特に限定するものではない。The structure of the positive electrode of the present invention may be the same as that of a normal positive electrode for a lithium secondary battery, except for the positive electrode active material. The positive electrode and the conductive material for ensuring the electronic conductivity of the active material may be used. It is composed of a material and a binder for binding the active material and the conductive material. In addition, the manufacturing method may be in accordance with a normal manufacturing method of a positive electrode for a lithium secondary battery, and the manufacturing method is not particularly limited.
【００２３】正極を構成する導電材には、アセチレンブ
ラック、ファーネスブラック等のカーボンブラックを用
いることができる。結着剤には、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
脂等を用いることができる。なお、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。As the conductive material constituting the positive electrode, carbon black such as acetylene black and furnace black can be used. As the binder, a fluorinated resin such as polytetrafluoroethylene, polyvinylidene fluoride, or fluororubber, or a thermoplastic resin such as polypropylene or polyethylene can be used. As a solvent for dispersing the active material, the conductive material, and the binder, N-methyl-2
-Organic solvents such as pyrrolidone can be used.
【００２４】本発明のリチウム二次電池用正極を製造す
る場合、上記活物質に上記導電材および結着剤を混合
し、適量の上記溶剤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、必要に応じて電極密度を高めるべく圧縮して
形成し、シート状のものとすることができる。シート状
の正極は、作製しようとするリチウム二次電池の、大き
さ、形状等に応じ、適正な寸法に裁断することができ
る。また、正極から外部への集電のために、集電用リー
ド等を正極に付設するものであってもよい。When the positive electrode for a lithium secondary battery of the present invention is produced, the above-mentioned active material is mixed with the above-mentioned conductive material and binder, and an appropriate amount of the above-mentioned solvent is added to obtain a paste-like positive electrode mixture. It can be coated and dried on the surface of a current collector made of a metal foil such as aluminum, and if necessary, compressed to increase the electrode density to form a sheet. The sheet-shaped positive electrode can be cut into appropriate dimensions according to the size, shape, and the like of the lithium secondary battery to be manufactured. In addition, a current collecting lead or the like may be attached to the positive electrode for current collection from the positive electrode to the outside.
【００２５】〈リチウム二次電池〉上記本発明の正極を
用いたリチウム二次電池は、その正極の他に、対向する
負極、正極負極間に挟装するセパレータ、非水電解液等
を主な構成要素として構成される。その一実施形態を説
明する。<Lithium Secondary Battery> A lithium secondary battery using the above-described positive electrode of the present invention mainly comprises, in addition to the positive electrode, an opposing negative electrode, a separator sandwiched between the positive and negative electrodes, a non-aqueous electrolyte, and the like. It is configured as a component. One embodiment will be described.
【００２６】負極は、負極活物質に金属リチウム、リチ
ウム合金、リチウムを吸蔵・離脱可能な炭素材料等を用
いて構成することができる。ただし、金属リチウム等を
負極に用いる場合、繰り返される充放電により負極表面
へのデンドライトの析出の可能性があり、二次電池の安
全性が懸念される。したがって、リチウム二次電池の安
全性を考慮する場合、負極活物質には、リチウムの吸蔵
・離脱可能な炭素材料を用いるのが望ましい。The negative electrode can be constituted by using metal lithium, a lithium alloy, a carbon material capable of inserting and extracting lithium, and the like as the negative electrode active material. However, when metallic lithium or the like is used for the negative electrode, dendrite may be deposited on the surface of the negative electrode due to repeated charging and discharging, and there is a concern about the safety of the secondary battery. Therefore, when considering the safety of the lithium secondary battery, it is desirable to use a carbon material capable of inserting and extracting lithium as the negative electrode active material.
【００２７】用いることができる炭素材料には、天然黒
鉛、球状あるいは繊維状の人造黒鉛、難黒鉛化性炭素、
および、フェノール樹脂等の有機化合物焼成体、コーク
ス等の易黒鉛化性炭素等の粉状体を挙げることができ
る。負極活物質となる炭素材料にはそれぞれの利点があ
り、作製しようとするリチウム二次電池の特性に応じて
選択すればよい。また炭素材料は１種のものを単独で用
いることもでき、２種以上を混合して用いることもでき
る。The carbon materials that can be used include natural graphite, spherical or fibrous artificial graphite, non-graphitizable carbon,
Further, there may be mentioned a fired body of an organic compound such as a phenol resin, and a powdered body of easily graphitizable carbon such as coke. The carbon material used as the negative electrode active material has respective advantages, and may be selected according to the characteristics of the lithium secondary battery to be manufactured. One type of carbon material can be used alone, or two or more types can be used in combination.
【００２８】負極活物質に炭素材料を用いる場合、負極
は、活物質に結着剤を混合し、必要に応じて適当な溶剤
を加えて、ペースト状の負極合材としたものを、正極同
様、銅等の金属箔製の集電体表面に塗布、乾燥し、その
後必要に応じプレス等にて負極合材の密度を高めること
によって形成する。結着剤としては、正極同様、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 a carbon material is used as the negative electrode active material, the negative electrode is prepared by mixing a binder with the active material and adding an appropriate solvent as necessary to obtain a paste-like negative electrode mixture, similar to the positive electrode. It is formed by coating and drying the surface of a current collector made of a metal foil such as copper, and then, if necessary, increasing the density of the negative electrode mixture by pressing or the like. As the binder, as in the positive electrode, a fluorine-containing resin such as polyvinylidene fluoride or the like is used.
Organic solvents such as -methyl-2-pyrrolidone can be used.
【００２９】なお、炭素材料を負極活物質として用いる
場合、負極を、リチウムを吸蔵・離脱可能な炭素材料
と、活性炭とを、活物質として含むように構成すること
ができる。前述した正極の場合と同様、活性炭の吸着力
を利用して、負極側のパワー密度をも向上させることが
可能となる。用いることのできる活性炭は、前記の活性
炭と同様のものとすることができる。また、正極の場合
と同様、その補助的機能およびシート電極としての成形
性に鑑み、活性炭の混合割合は、リチウムを吸蔵・離脱
可能な主たる炭素材料と活性炭との合計を１００ｗｔ％
とした場合に、活性炭を１５ｗｔ％以下とすることが望
ましい。When a carbon material is used as the negative electrode active material, the negative electrode can be configured to include a carbon material capable of inserting and extracting lithium and activated carbon as the active material. As in the case of the positive electrode described above, the power density on the negative electrode side can be improved by utilizing the adsorption power of the activated carbon. The activated carbon that can be used can be the same as the above-mentioned activated carbon. As in the case of the positive electrode, in view of its auxiliary function and formability as a sheet electrode, the mixing ratio of activated carbon is 100 wt% of the total of the main carbon material capable of inserting and extracting lithium and the activated carbon.
In this case, the content of activated carbon is desirably 15 wt% or less.
【００３０】正極と負極の間に挟装されるセパレータ
は、正極と負極とを分離し電解液を保持するものであ
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。また非水電解液は、有機溶媒に電
解質であるリチウム塩を溶解させたもので、有機溶媒
は、高誘電率でありかつ低粘性であることが望ましく、
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、エ
チルメチルカーボネート、γ−ブチロラクトン、アセト
ニトリル、１，２−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種以上の混合溶媒を用いることができる。また、
溶解させる電解質としては、ＬｉＩ、ＬｉＣｌＯ4、Ｌ
ｉＡｓＦ6、ＬｉＢＦ4、ＬｉＰＦ6、ＬｉＮ（ＣＦ3ＳＯ
2）2等のリチウム塩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 and the negative electrode and holds the electrolyte, and a thin microporous film of polyethylene, polypropylene or the like can be used. The non-aqueous electrolyte is obtained by dissolving a lithium salt as an electrolyte in an organic solvent, and the organic solvent preferably has a high dielectric constant and a low viscosity,
For example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, acetonitrile, 1,2-dimethoxyethane, tetrahydrofuran, dioxolan, methylene chloride, or a mixed solvent of two or more of these. Can be used. Also,
As the electrolyte to be dissolved, LiI, LiClO 4 , L
iAsF 6 , LiBF 4 , LiPF 6 , LiN (CF 3 SO
2 ) Lithium salts such as 2 can be used.
【００３１】以上のものを主構成要素として構成される
リチウム二次電池であるが、その形状は円筒型、積層
型、コイン型、カード型等、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、そして正極集
電体および負極集電体から外部に通ずる正極端子および
負極端子までの間を集電用リード等を用いて接続し、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リ
チウム電池を完成することができる。The above-described lithium secondary battery is constituted as a main component. The shape of the lithium secondary battery can be various types such as a cylindrical type, a stacked type, a coin type, and a card type. Regardless of the shape used, a separator is sandwiched between the positive electrode and the negative electrode to form an electrode body, and current is collected from the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal that lead to the outside. The electrodes are connected using a lead or the like, and the electrode body is sealed in a battery case together with the non-aqueous electrolyte to complete a lithium battery.
【００３２】なおこれまでに説明した実施形態は例示に
過ぎず、本発明のリチウム二次電池用正極およびそれを
用いた本発明の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。The embodiments described so far are merely examples, and the positive electrode for a lithium secondary battery of the present invention and the lithium secondary battery of the present invention using the same can be obtained by those skilled in the art including the above-described embodiment. Various modifications and improvements can be made based on knowledge.
【００３３】[0033]
【実施例】上記実施形態の基づいて、実際にスピネル構
造リチウムマンガン複合酸化物と活性炭との混合物を正
極活物質とした正極を製造し、この正極を用いてリチウ
ム二次電池を作製した。そして、正極活物質に活性炭を
添加したことによるリチウム二次電池のパワー密度の改
善効果を確認した。以下に、実施例として示す。EXAMPLES Based on the above embodiment, a positive electrode was actually manufactured using a mixture of a spinel-structured lithium manganese composite oxide and activated carbon as a positive electrode active material, and a lithium secondary battery was manufactured using this positive electrode. Then, the effect of improving the power density of the lithium secondary battery by adding activated carbon to the positive electrode active material was confirmed. The following is an example.
【００３４】〈作製したリチウム二次電池〉正極は、組
成式Ｌｉ1.05Ｍｎ0.19Ａｌ0.05Ｏ4（試作品）で表され
るスピネル構造リチウムマンガン複合酸化物と、活性炭
（キャパシタ用市販品；ＢＥＴ比表面積６００ｍ2／
ｇ）とを、重量比で７０：３０〜１００：０の範囲で混
合した数種のものを活物質として用いた。まず、それぞ
れの活物質８５重量部に、導電材としてのカーボンブラ
ック１０重量部と結着剤としてのポリフッ化ビニリデン
５重量部とを混合し、適量のＮ−メチル−２−ピロリド
ンを添加し、ペースト状の正極合材を得た。次いで、こ
のペースト状の正極合材を、厚さ２０μｍのＡｌ箔製集
電体の両面に塗布し、乾燥後、プレスして、数種のシー
ト状の正極を完成させた。なお、シート状の正極の大き
さは５４ｍｍ×４５０ｍｍで、正極合材のプレス後の厚
さは片面あたり４０μｍとした。<Prepared Lithium Secondary Battery> The positive electrode was composed of a lithium manganese composite oxide having a spinel structure represented by a composition formula Li 1.05 Mn 0.19 Al 0.05 O 4 (prototype) and activated carbon (commercially available product for capacitors; BET ratio Surface area 600m 2 /
g) was used as an active material by mixing several kinds in a weight ratio of 70:30 to 100: 0. First, to 85 parts by weight of each active material, 10 parts by weight of carbon black as a conductive material and 5 parts by weight of polyvinylidene fluoride as a binder were mixed, and an appropriate amount of N-methyl-2-pyrrolidone was added, A paste-like positive electrode mixture was obtained. Next, this paste-like positive electrode mixture was applied to both surfaces of a 20-μm-thick Al foil current collector, dried, and pressed to complete several types of sheet-like positive electrodes. The size of the sheet-shaped positive electrode was 54 mm × 450 mm, and the thickness of the positive electrode mixture after pressing was 40 μm per side.
【００３５】負極は、人造黒鉛（市販品）と正極の製造
で用いたのと同じ活性炭とを重量比で７０：３０〜１０
０：０の範囲で混合した数種のものを活物質として用い
た。まず、それぞれの活物質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、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
合材を得た。次いで、このペースト状の負極合材を、厚
さ１０μｍのＣｕ箔製集電体の両面に塗布し、乾燥後、
プレスして、数種のシート状の負極を完成させた。な
お、シート状の負極の大きさは５６ｍｍ×５００ｍｍ
で、負極合材のプレス後の厚さは片面あたり５０μｍと
した。The negative electrode was prepared by mixing artificial graphite (commercially available) with the same activated carbon used in the production of the positive electrode in a weight ratio of 70:30 to 10:30.
Several kinds mixed in the range of 0: 0 were used as active materials. First, 95 parts by weight of each active material was mixed with 5 parts by weight of polyvinylidene fluoride as a binder, and an appropriate amount of N was added.
-Methyl-2-pyrrolidone was added to obtain a paste-like negative electrode mixture. Next, this paste-like negative electrode mixture was applied to both sides of a Cu foil current collector having a thickness of 10 μm, and after drying,
By pressing, several types of sheet-shaped negative electrodes were completed. The size of the sheet-shaped negative electrode was 56 mm × 500 mm.
The thickness of the negative electrode mixture after pressing was 50 μm per side.
【００３６】上記それぞれの正極および負極を、その間
にポリエチレン製セパレータ（厚さ２５μｍ；市販品）
を挟装して捲回し、ロール状の電極体を形成させた。こ
の電極体を、１８６５０型円筒電池ケースに挿設し、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電解質としてＬｉＰＦ 6
を１Ｍの濃度で溶解した非水電解液を注入後、その電池
ケースを密閉してリチウム二次電池を完成させた。The above positive electrode and negative electrode were placed between them.
Polyethylene separator (thickness 25 μm; commercially available)
Was wound while being sandwiched to form a roll-shaped electrode body. This
Of the electrode body of the 18650 type cylindrical battery case,
Volume ratio of ethylene carbonate and diethyl carbonate
LiPF as an electrolyte in a mixed solvent 1: 1 mixed with 6
After injecting a non-aqueous electrolyte in which
The case was sealed to complete the lithium secondary battery.
【００３７】リチウム二次電池は、正極と負極との組み
合わせにより７種類のものを作製し、下記表１に示すよ
うに、それぞれ電池Ｎｏ．１〜Ｎｏ．７のリチウム二次
電池とした。なお、この中で電池Ｎｏ．１の二次電池
は、正極活物質として活性炭を含んでおらず、本発明の
リチウム二次電池用正極によっては構成されたものとは
なっていない。また、正極、負極とも、活性炭の添加割
合が１５ｗｔ％を超える活物質を用いようとしたもの
は、結着力不足となり、良好なシート電極とはならなか
ったため、これらの電極を用いたリチウム二次電池の製
作を断念した。As shown in Table 1 below, seven types of lithium secondary batteries were prepared by combining a positive electrode and a negative electrode. 1 to No. No. 7 lithium secondary battery. Note that, among them, the battery No. The secondary battery of No. 1 does not contain activated carbon as a positive electrode active material, and is not constituted by the positive electrode for a lithium secondary battery of the present invention. In addition, when the positive electrode and the negative electrode use an active material in which the addition ratio of activated carbon exceeds 15 wt%, the binding force is insufficient, and the sheet does not become a good sheet electrode. Abandoned battery production.
【００３８】〈充放電試験〉上記Ｎｏ．１〜Ｎｏ．７の
二次電池を、室温で１週間放置するエージング処理を行
った。そしてその後、それぞれの二次電池に対して、２
０℃におけるパワー特性、サイクル特性を評価するため
の充放電試験を行った。<Charging / discharging test> 1 to No. The secondary battery of No. 7 was subjected to an aging treatment in which it was left at room temperature for one week. And then, for each secondary battery, 2
A charge / discharge test for evaluating power characteristics and cycle characteristics at 0 ° C. was performed.
【００３９】パワー特性評価のための充放電試験は、そ
れぞれの二次電池を２０℃の恒温槽内に保持し、それぞ
れ約３０％、５０％、８０％のＳＯＣ（充電状態）に充
放電させて、放電パワー密度（出力パワー密度）および
充電パワー密度（入力パワー密度）を求めるものとし
た。なお、ＳＯＣとは、可逆的に充放電可能な範囲にお
ける満充電状態を１００％と空放電状態を０％として規
定される充電状態をいい、より具体的には、充電終止電
圧４．２Ｖまで定電流定電圧充電した状態をＳＯＣ＝１
００％とし、放電終止電圧３．０Ｖまで定電流放電した
状態をＳＯＣ＝０％としている。In a charge / discharge test for evaluating power characteristics, each secondary battery was held in a thermostat at 20 ° C. and charged and discharged to SOCs (charged states) of about 30%, 50%, and 80%, respectively. Then, the discharge power density (output power density) and the charge power density (input power density) were determined. The SOC refers to a state of charge defined as 100% for a fully charged state and 0% for an idle state in a reversibly chargeable / dischargeable range, and more specifically, up to a charge end voltage of 4.2V. SOC = 1 when charging at constant current and constant voltage
SOC is set to 0%, and a state where constant current discharge is performed to a discharge end voltage of 3.0 V is set to SOC = 0%.
【００４０】放電パワー密度は、上記それぞれのＳＯＣ
において、電流を変化させて放電を行ったときの１０秒
後の電池電圧ＶDを測定し、ＶDが３．０Ｖになるであろ
う電流値ＡDを外挿することによって求め、次式により
算出したものである。（放電パワー密度＝ＡD×３．０
／電極体重量） また、充電パワー密度は、上記それぞ
れのＳＯＣにおいて、電流を変化させて充電を行ったと
きの１０秒後の電池電圧ＶCを測定し、ＶCが４．２Ｖに
なるであろう電流値ＡCを外挿することによって求め、
次式により算出したものである。（充電パワー密度＝Ａ
C×４．２／電極体重量） したがって、放電パワー密度が高い電池ほど、１０秒程
度を上限とした高電流密度の放電特性に優れ、充電パワ
ー密度が高い電池ほど、１０秒程度を上限とした高電流
密度の充電特性に優れたリチウム二次電池であるとする
ことができる。これを電気自動車用電源に搭載した場合
に当て嵌めてみると、放電パワー密度が高い電池ほど、
電気自動車の加速性能が良好になり、充電パワー密度が
高いほど、減速時の回生効率が良好になる。The discharge power density is determined by the above SOC
In the above, the battery voltage V D after 10 seconds from when the discharge was performed while changing the current was measured, and the current value A D at which V D would be 3.0 V was obtained by extrapolation, and the following equation was obtained. It is calculated by: (Discharge power density = A D × 3.0
/ Electrode weight amount) The charging power density, in the above each SOC, measure the battery voltage V C after 10 seconds when performing charging by changing the current, the V C becomes 4.2V the current value a C which will allo determined by extrapolating,
It is calculated by the following equation. (Charging power density = A
C × 4.2 / electrode weight amount) Therefore, as the discharge power density is high battery, excellent for about 10 seconds to discharge characteristics of high current density was made the upper limit, as the charging power density high battery, and up to about 10 seconds Thus, it can be said that the lithium secondary battery is excellent in charge characteristics with high current density. If this is applied to a power supply for an electric vehicle, the higher the discharge power density of the battery,
The better the acceleration performance of the electric vehicle and the higher the charging power density, the better the regeneration efficiency during deceleration.
【００４１】サイクル特性を評価するための充放電試験
は、２０℃の恒温槽内にそれぞれの二次電池を保持し、
電流密度１ｍＡ／ｃｍ2の定電流で充電終止電圧４．２
Ｖまで充電後４．２Ｖにおいて２時間の充電を行う定電
流定電圧充電行い、その後、電流密度１ｍＡ／ｃｍ2の
定電流で放電終止電圧３．０Ｖまで放電を行う定電流放
電を行う充放電サイクルを１サイクルとし、この充放電
サイクルを１００サイクルまで繰り返すものとした。In a charge / discharge test for evaluating cycle characteristics, each secondary battery was held in a thermostat at 20 ° C.
End-of-charge voltage of 4.2 at constant current of 1 mA / cm 2 current density
After charging to V, constant-current constant-voltage charging is performed at 4.2 V for 2 hours, and then constant-current discharging is performed at a constant current of 1 mA / cm 2 to a discharge end voltage of 3.0 V. The cycle was defined as one cycle, and this charge / discharge cycle was repeated up to 100 cycles.
【００４２】そして、１サイクル目の放電容量を初期放
電容量とし、初期放電容量に対する１００サイクル目の
放電容量の百分率を求め容量維持率とし、この容量維持
率によってサイクル特性を評価するものとした。The discharge capacity at the first cycle was defined as the initial discharge capacity, the percentage of the discharge capacity at the 100th cycle with respect to the initial discharge capacity was determined and defined as the capacity retention rate, and the cycle characteristics were evaluated based on the capacity retention rate.
【００４３】〈評価〉上記充放電試験の結果として、下
記表１に、Ｎｏ．１〜Ｎｏ．７の各二次電池の正極活物
質および負極活物質の構成、正極活物質単位重量あたり
の初期放電容量、容量維持率について示し、図１に各二
次電池の放電パワー密度を、図２に各二次電池の充電パ
ワー密度を、それぞれ示す。<Evaluation> As a result of the above charge / discharge test, No. 1 to No. 7 shows the configuration of the positive electrode active material and the negative electrode active material of each secondary battery, the initial discharge capacity per unit weight of the positive electrode active material, and the capacity retention ratio. FIG. 1 shows the discharge power density of each secondary battery. The charging power density of each secondary battery is shown.
【００４４】[0044]
【表１】 [Table 1]
【００４５】図１から明らかなように、いずれのＳＯＣ
においても、放電パワー密度は、各二次電池においてそ
の値に大きな差異はない。これにより、スピネル構造リ
チウムマンガン複合酸化物を正極活物質に用いた場合の
特徴である高い放電パワー密度は、正負極に活物質とし
て活性炭を添加した場合であっても損なわれることがな
いことが確認できる。As is apparent from FIG.
Also in the above, there is no large difference in the discharge power density between the respective secondary batteries. As a result, the high discharge power density, which is a feature when the spinel structure lithium manganese composite oxide is used as the positive electrode active material, is not impaired even when activated carbon is added as the active material to the positive and negative electrodes. You can check.
【００４６】これに対し、図２から明らかなように、い
ずれのＳＯＣにおいても、充電パワー密度は、正極活物
質として活性炭を添加した正極を用いた二次電池と、添
加していない正極を用いた二次電池とでは大きな差異が
見られた。活性炭を添加した場合は、添加していない場
合と比較して、充電パワー密度が高く、スピネル構造リ
チウムマンガン複合酸化物を正極活物質に用いた場合の
欠点である低い充電パワー密度が、正極活物質として活
性炭を添加することにより改善されることが確認でき
る。On the other hand, as is apparent from FIG. 2, the charging power density of each of the SOCs is determined by using a secondary battery using a positive electrode to which activated carbon is added as a positive electrode active material and a positive electrode not adding an active carbon. There was a great difference from the secondary battery that was used. When activated carbon was added, the charging power density was higher than when it was not added, and the low charging power density, which is a drawback when the spinel-structured lithium manganese composite oxide was used as the positive electrode active material, was higher than that when activated carbon was not added. It can be confirmed that the improvement is achieved by adding activated carbon as a substance.
【００４７】また、同じ正極を用いた二次電池であって
も、負極活物質に活性炭を添加した負極を用いた二次電
池は、活性炭を添加していない負極を用いた二次電池と
比較して、充電パワー密度が若干高く、負極活物質とし
て活性炭を添加する効果が認められた。Further, even with a secondary battery using the same positive electrode, a secondary battery using a negative electrode in which activated carbon is added to the negative electrode active material is compared with a secondary battery using a negative electrode in which no activated carbon is added. As a result, the charging power density was slightly higher, and the effect of adding activated carbon as the negative electrode active material was recognized.
【００４８】なお、正極活物質としての活性炭の添加割
合が１０ｗｔ％の場合と１５ｗｔ％の場合とでは、充電
パワー密度の大きな差異がない。これは、今回の試験に
おけるパワー密度の評価が１０秒間程度の短時間による
場合の評価であるためと考えられ、充電時間を延長して
行えばその差が認められるものと考える。また、今回作
製した二次電池に活物質として添加した活性炭は、比表
面積が６００ｍ2／ｇと比較的小さいものであり、シー
ト電極を形成できるものである限り、比表面積の大きい
活性炭を使用することによって、より大きな充電パワー
密度の改善効果が期待できるものと考える。There is no significant difference in the charging power density between the case where the addition ratio of the activated carbon as the positive electrode active material is 10 wt% and the case where the addition ratio is 15 wt%. This is considered to be because the evaluation of the power density in this test was performed in a short time of about 10 seconds, and it is considered that the difference is recognized if the charging time is extended. The activated carbon added as an active material to the secondary battery produced this time has a relatively small specific surface area of 600 m 2 / g. As long as a sheet electrode can be formed, activated carbon having a large specific surface area is used. Thus, it is expected that a greater effect of improving the charging power density can be expected.
【００４９】上記表１に示すように、初期放電容量およ
びサイクル特性については、Ｎｏ．１〜Ｎｏ．７のいず
れの二次電池もその値に顕著な差異はなく、容量および
サイクル特性が、活物質として活性炭を添加することに
よって損なわれることがないことが確認できる。As shown in Table 1 above, the initial discharge capacity and cycle characteristics 1 to No. In any of the secondary batteries of No. 7, there is no significant difference in the values, and it can be confirmed that the capacity and the cycle characteristics are not impaired by adding activated carbon as an active material.
【００５０】[0050]
【発明の効果】本発明のリチウム二次電池用正極は、ス
ピネル構造リチウムマンガン複合酸化物と活性炭とを活
物質として含むように構成するものである。このような
構成とすることで、本発明のリチウム二次電池用正極
は、安価であり、かつ、充電パワー密度に優れたリチウ
ム二次電池を構成することができる正極となる。The positive electrode for a lithium secondary battery according to the present invention is constituted so as to contain a spinel structure lithium manganese composite oxide and activated carbon as active materials. With such a configuration, the positive electrode for a lithium secondary battery of the present invention is a positive electrode that is inexpensive and can form a lithium secondary battery having excellent charging power density.
【図１】 実施例における各リチウム二次電池の放電パ
ワー密度を示す。FIG. 1 shows the discharge power density of each lithium secondary battery in an example.
【図２】 実施例における各リチウム二次電池の充電パ
ワー密度を示す。FIG. 2 shows a charging power density of each lithium secondary battery in an example.
───────────────────────────────────────────────────── 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） 5H003 AA02 AA08 BB05 BB15 BC01 BC06 BD04 5H014 AA02 AA06 EE08 EE10 HH01 5H029 AJ03 AJ14 AK03 AL06 AM03 AM04 AM05 AM07 DJ08 DJ16 DJ17 HJ01 HJ13 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yoshio Ukyo F-term in Toyota Central R & D Laboratories Co., Ltd. 41 No. 41, Chukumi Yokomichi, Nagakute-cho, Aichi Prefecture 5H003 AA02 AA08 BB05 BB15 BC01 BC06 BD04 5H014 AA02 AA06 EE08 EE10 HH01 5H029 AJ03 AJ14 AK03 AL06 AM03 AM04 AM05 AM07 DJ08 DJ16 DJ17 HJ01 HJ13
Claims (3)
物と、活性炭とを、活物質として含むリチウム二次電池
用正極。1. A positive electrode for a lithium secondary battery, comprising a lithium manganese composite oxide having a spinel structure and activated carbon as active materials.
酸化物と前記活性炭との合計を１００ｗｔ％とした場合
に、該活性炭を５ｗｔ％以上１５ｗｔ％以下の割合で含
む請求項１に記載のリチウム二次電池用正極。2. The lithium secondary battery according to claim 1, wherein the active carbon is contained at a ratio of 5 wt% or more and 15 wt% or less, when the total of the spinel-structured lithium manganese composite oxide and the activated carbon is 100 wt%. For positive electrode.
物と、活性炭とを、活物質として含む正極と、 リチウムを吸蔵・離脱可能な炭素材料と、活性炭とを活
物質として含む負極とを備えてなるリチウム二次電池。3. A lithium battery comprising: a positive electrode containing a spinel-structured lithium manganese composite oxide; activated carbon as an active material; a carbon material capable of storing and releasing lithium; and a negative electrode containing activated carbon as an active material. Rechargeable battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29079799A JP2001110418A (en) | 1999-10-13 | 1999-10-13 | Positive electrode for lithium secondary battery and the lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29079799A JP2001110418A (en) | 1999-10-13 | 1999-10-13 | Positive electrode for lithium secondary battery and the lithium secondary battery |
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| Publication Number | Publication Date |
|---|---|
| JP2001110418A true JP2001110418A (en) | 2001-04-20 |
Family
ID=17760631
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29079799A Pending JP2001110418A (en) | 1999-10-13 | 1999-10-13 | Positive electrode for lithium secondary battery and the lithium secondary battery |
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| Country | Link |
|---|---|
| JP (1) | JP2001110418A (en) |
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