JPH10188958A - Negative electrode for lithium secondary battery - Google Patents
Negative electrode for lithium secondary batteryInfo
- Publication number
- JPH10188958A JPH10188958A JP8355336A JP35533696A JPH10188958A JP H10188958 A JPH10188958 A JP H10188958A JP 8355336 A JP8355336 A JP 8355336A JP 35533696 A JP35533696 A JP 35533696A JP H10188958 A JPH10188958 A JP H10188958A
- Authority
- JP
- Japan
- Prior art keywords
- coke
- negative electrode
- secondary battery
- lithium
- lithium secondary
- 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
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 51
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 239000000571 coke Substances 0.000 claims abstract description 91
- 239000000758 substrate Substances 0.000 claims abstract description 38
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910052796 boron Inorganic materials 0.000 claims abstract description 33
- 238000010438 heat treatment Methods 0.000 abstract description 10
- 239000003245 coal Substances 0.000 abstract description 7
- 239000003208 petroleum Substances 0.000 abstract description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 33
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 32
- 229910001416 lithium ion Inorganic materials 0.000 description 32
- 229910002804 graphite Inorganic materials 0.000 description 19
- 239000010439 graphite Substances 0.000 description 19
- 229910052799 carbon Inorganic materials 0.000 description 13
- 210000004027 cell Anatomy 0.000 description 11
- 150000002641 lithium Chemical group 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 239000010410 layer Substances 0.000 description 7
- -1 polytetrafluoroethylene Polymers 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000010000 carbonizing Methods 0.000 description 2
- 239000003610 charcoal Substances 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- HMQFJYLWNWIYKQ-UHFFFAOYSA-N 1,4-diphenylbutadiyne Chemical group C1=CC=CC=C1C#CC#CC1=CC=CC=C1 HMQFJYLWNWIYKQ-UHFFFAOYSA-N 0.000 description 1
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229920000265 Polyparaphenylene Polymers 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
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
- Battery Electrode And Active Subsutance (AREA)
Abstract
(57)【要約】
【課題】 充放電容量の大きなリチウム二次電池を得る
ことができる，リチウム二次電池用負極を提供するこ
と。
【解決手段】 負極基体にリチウムを吸蔵させてなる。
上記負極基体はコークスとホウ素とよりなり，該ホウ素
の添加量が上記コークスと上記ホウ素との合計量に対し
て０．１〜５ｗｔ％である。上記コークスは，例えば石
油又は石炭の生コークスを５００〜９００℃にて加熱す
ることにより得られた熱処理コークス１よりなる。
(57) [Problem] To provide a negative electrode for a lithium secondary battery capable of obtaining a lithium secondary battery having a large charge / discharge capacity. SOLUTION: A negative electrode substrate is made to occlude lithium.
The negative electrode substrate is composed of coke and boron, and the added amount of the boron is 0.1 to 5% by weight based on the total amount of the coke and the boron. The coke is, for example, a heat-treated coke 1 obtained by heating raw coke of petroleum or coal at 500 to 900 ° C.
Description
【０００１】[0001]
【技術分野】本発明は，充放電容量に優れたリチウム二
次電池用負極に関する。TECHNICAL FIELD The present invention relates to a negative electrode for a lithium secondary battery having excellent charge / discharge capacity.
【０００２】[0002]
【従来技術】近年，携帯電話のような電子機器の小型
化，コードレス化が急速に進んでいる。また，環境問
題，エネルギー問題から，電気自動車の開発，普及が望
まれている。これらに伴い，高いエネルギー密度を有す
る二次電池が要求されている。2. Description of the Related Art In recent years, miniaturization and cordlessness of electronic devices such as mobile phones have been rapidly progressing. In addition, development and diffusion of electric vehicles are desired due to environmental problems and energy problems. Accordingly, a secondary battery having a high energy density is required.
【０００３】従来，二次電池としては，ニッケルカドミ
ウム電池，ニッケル水素電池，鉛蓄電池が知られてい
る。ところが，これらの電池は重量が重く，エネルギー
密度が低い。これらに対して，リチウム二次電池は重量
が軽く，エネルギー密度が高く，高性能な携帯電話用電
池，電気自動車用電池等として期待されている。Conventionally, nickel cadmium batteries, nickel-metal hydride batteries, and lead-acid batteries have been known as secondary batteries. However, these batteries are heavy and have low energy density. On the other hand, lithium secondary batteries are expected to be lightweight, high in energy density, high performance batteries for mobile phones, batteries for electric vehicles, and the like.
【０００４】ところが，リチウム二次電池において負極
にリチウム金属を用いた場合には，充放電時にリチウム
金属が負極表面においてデンドライト状，パウダー状な
どの活性状態で析出するため，これがセパレータを貫通
し，正極と短絡したり，電解液と反応する。これによ
り，リチウム二次電池の充放電効率が低下する。However, when lithium metal is used for the negative electrode in a lithium secondary battery, the lithium metal precipitates in an active state such as dendrite or powder on the surface of the negative electrode during charge / discharge, so that the lithium metal penetrates through the separator. Short circuit with positive electrode or react with electrolyte. As a result, the charge / discharge efficiency of the lithium secondary battery decreases.
【０００５】そこで，充電したときリチウムイオンを層
間にインタカレーションし，デンドライト析出や電解液
との反応を抑制することができる黒鉛が，上記リチウム
二次電池用負極における負極基体として使用できる。ま
た，黒鉛は電気抵抗が小さく，充放電電圧が平坦であ
り，負極基体（負極活物質）として有望視されていた。
しかし，黒鉛は，高容量密度が要求されるリチウム二次
電池の負極としては容量が不足している。[0005] Therefore, graphite which can intercalate lithium ions between layers when charged and suppress dendrite deposition and reaction with an electrolyte can be used as a negative electrode substrate in the negative electrode for a lithium secondary battery. In addition, graphite has a small electric resistance and a flat charge / discharge voltage, and has been regarded as promising as a negative electrode substrate (a negative electrode active material).
However, graphite has insufficient capacity as a negative electrode of a lithium secondary battery that requires a high capacity density.
【０００６】そこで，特開平５−２９０８４３号では，
ホウ素を添加し，リチウムイオン吸蔵量を増加させた黒
鉛基体を開示している。しかし，この場合は容量の問題
を解決できるものの，黒鉛の特徴である高電圧の充電が
必要であることには変わりなく，ハイレート充電時に生
ずる電圧降下によって充電不足を起こす場合がある。Therefore, in Japanese Patent Application Laid-Open No. Hei 5-290843,
Disclosed is a graphite substrate to which boron is added to increase the lithium ion storage capacity. However, in this case, although the capacity problem can be solved, charging at a high voltage, which is a feature of graphite, is still required, and charging may be insufficient due to a voltage drop that occurs during high-rate charging.
【０００７】そこで，黒鉛に代わる負極基体として特開
平３−２４５４５８号で開示されるように，樹脂を炭素
化したものを負極として用いることもできる。しかし，
負極基体中の結晶子の配向性が悪いため，表面積が大き
く，密度が小さい。したがって，各炭素結晶子内部（層
間）および各炭素結晶子の末端間のキャビティにリチウ
ムイオンを吸蔵することはできるものの，充放電容量が
小さいという欠点がある。これを補うために特開平３−
２４５４５８号では，さらにホウ素を添加することによ
り，リチウムイオン吸蔵量を増加させている。しかし，
密度が小さいことには変わりなく，充放電容量の問題は
解決されていない。Thus, as disclosed in Japanese Patent Application Laid-Open No. 3-245458, as a negative electrode substrate instead of graphite, carbonized resin can be used as the negative electrode. However,
Since the orientation of crystallites in the negative electrode substrate is poor, the surface area is large and the density is small. Therefore, although lithium ions can be occluded in the interior (interlayer) of each carbon crystallite and in the cavity between the terminals of each carbon crystallite, there is a disadvantage that the charge / discharge capacity is small. To compensate for this, Japanese Patent Application Laid-Open
In 245458, the amount of lithium ions stored is increased by further adding boron. However,
The density is still low, and the problem of charge / discharge capacity has not been solved.
【０００８】一方，特開平１−２２１８５９号で開示さ
れるようにコークス自体を負極として用いることもでき
る。コークスはリチウムを吸蔵することができ，かつ低
コストである点が有利である。更に，コークスの密度
は，樹脂を炭素化したものに比べて大きく，容量も大き
い。なお，上記コークスとは，石油又は石炭を高温乾留
（１２００〜１４００℃）して得られる灰黒色の多孔質
固体である。On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 1-221859, coke itself can be used as the negative electrode. Advantageously, coke can store lithium and is low cost. Further, the density of coke is higher than that of carbonized resin, and the capacity is larger. The coke is a gray-black porous solid obtained by high-temperature carbonization (1200-1400 ° C.) of petroleum or coal.
【０００９】[0009]
【解決しようとする課題】しかしながら，上記コークス
よりなる負極には以下の問題点がある。即ち，上記コー
クスよりなる負極は導電性が悪いうえ，該コークスを構
成するコークス結晶子が大きいため，吸蔵可能なリチウ
ムイオンの量は理論容量よりも少ない。よって，上記コ
ークスを用いたリチウム二次電池においては，充放電容
量の大きいものが得られない。However, the negative electrode made of coke has the following problems. That is, since the negative electrode composed of the coke has poor conductivity and the coke crystallites constituting the coke are large, the amount of lithium ions that can be stored is smaller than the theoretical capacity. Therefore, a lithium secondary battery using the above coke cannot have a large charge / discharge capacity.
【００１０】なお，上記理論容量とは，上記負極基体を
炭素の極限構造である黒鉛によって作製したと仮定した
場合のものである。即ち，上記黒鉛の層状構造の各層間
へのリチウムイオンのインタカレーション（第一ステー
ジ）により，上記負極基体にリチウムイオンが吸蔵され
る。この場合，炭素原子６個に対しリチウム原子１個を
吸蔵することができ，負極基体１ｇあたりの充放電容量
は３７２ｍＡｈｇ-1であり，これが理論容量である。The above-mentioned theoretical capacity is based on the assumption that the above-mentioned negative electrode substrate is made of graphite, which is an extreme structure of carbon. That is, lithium ions are occluded in the negative electrode substrate by intercalation (first stage) of lithium ions between the layers of the graphite layer structure. In this case, one lithium atom can be stored for six carbon atoms, and the charge / discharge capacity per gram of the negative electrode substrate is 372 mAhg −1 , which is the theoretical capacity.
【００１１】本発明は，かかる問題点に鑑み，充放電容
量の大きなリチウム二次電池を得ることができる，リチ
ウム二次電池用負極を提供しようとするものである。The present invention has been made in view of the above problems, and an object of the present invention is to provide a negative electrode for a lithium secondary battery, which can obtain a lithium secondary battery having a large charge / discharge capacity.
【００１２】[0012]
【課題の解決手段】請求項１の発明は，負極基体にリチ
ウムを吸蔵させてなるリチウム二次電池用負極であっ
て，上記負極基体はコークスとホウ素とよりなり，該ホ
ウ素の添加量は，上記コークスと上記ホウ素との合計量
（１００ｗｔ％）に対して０．１〜５ｗｔ％であること
を特徴とするリチウム二次電池用負極にある。According to the first aspect of the present invention, there is provided a negative electrode for a lithium secondary battery in which lithium is occluded in a negative electrode substrate, wherein the negative electrode substrate comprises coke and boron. The negative electrode for a lithium secondary battery is characterized in that the amount is 0.1 to 5 wt% with respect to the total amount (100 wt%) of the coke and the boron.
【００１３】上記ホウ素の添加量が０．１ｗｔ％未満の
場合には，コークスのみの場合の特性と殆ど変わらず，
したがって充放電容量の大きいものが得られない。一
方，上記添加量が５ｗｔ％より大きい場合には，導電性
が低下して，分極が大きくなり，充分に充放電ができな
くなるおそれがある。When the amount of boron is less than 0.1 wt%, the characteristics are almost the same as those of coke alone.
Therefore, a battery having a large charge / discharge capacity cannot be obtained. On the other hand, if the addition amount is more than 5 wt%, the conductivity may be reduced, the polarization may be increased, and sufficient charge / discharge may not be performed.
【００１４】次に，本発明の作用につき，以下に説明す
る。まず，コークスへのリチウムの吸蔵は，図１に示す
ようにコークス結晶子の層間および該末端間のキャビテ
ィにリチウムイオンが吸蔵されるものである。コークス
へのホウ素添加による，リチウムイオン吸蔵量向上の効
果は，次の理由によるものと推定される。即ち，ホウ素
を添加することは，抵抗の高いコークスへの一種のドー
ピングである。ホウ素は炭素に比べて最外殻の電子が一
個少なく，電子を吸引し易いため，負の電荷を帯び易
い。このため，ホウ素の周辺のリチウムイオンは，炭素
の周辺に比べてより安定に存在することができる。Next, the operation of the present invention will be described below. First, as for the occlusion of lithium in coke, as shown in FIG. 1, lithium ions are occluded in the cavities between the layers of the coke crystallites and between the terminals. The effect of increasing the amount of lithium ions absorbed by adding boron to coke is presumed to be due to the following reasons. That is, adding boron is a kind of doping to coke having high resistance. Boron has one less outermost electron than carbon and is easy to attract electrons, so it tends to be negatively charged. Therefore, lithium ions around boron can be more stably present than around carbon.
【００１５】つまり，ホウ素の添加によって，このよう
なドナーサイトがコークス内に多数形成される。このサ
イトが，リチウムイオンの吸着サイトとなり，リチウム
イオンの吸蔵量が増加すると考えられる。一方，黒鉛に
対するホウ素の添加効果について検討すると，この場合
には，黒鉛が良導体であることから，このような吸着サ
イトの形成がコークスの場合より少なく，リチウムイオ
ン吸蔵量を増加させる効果がコークスの場合より小さい
（図３参照）。That is, by the addition of boron, many such donor sites are formed in the coke. This site becomes a lithium ion adsorption site, and it is considered that the amount of lithium ion absorbed increases. On the other hand, when examining the effect of adding boron to graphite, in this case, since graphite is a good conductor, the formation of such adsorption sites is smaller than in the case of coke, and the effect of increasing the amount of lithium ions absorbed by coke is Smaller than the case (see FIG. 3).
【００１６】以上により，本発明によれば，充放電容量
の大きなリチウム二次電池を得ることができる，リチウ
ム二次電池用負極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 negative electrode for a lithium secondary battery capable of obtaining a lithium secondary battery having a large charge / discharge capacity.
【００１７】また，本発明にかかるリチウム二次電池用
負極は，上述のリチウムを吸蔵させるための負極基体以
外に，例えば集電体，結着剤等を併用する場合がある。
例えば，上述の負極基体に黒鉛を添加すると，黒鉛は負
極基体における電気伝導のネットワークとして働き，そ
の集電効果により，負極基体内のコークスの充放電容量
を増加させることができる。また，黒鉛自身もリチウム
イオンを吸蔵することができ，負極基体として働くこと
ができるため，コークスのみにホウ素を添加した場合と
比較して，更に充放電容量を高めることができる。The negative electrode for a lithium secondary battery according to the present invention may use, for example, a current collector or a binder in addition to the above-described negative electrode substrate for absorbing lithium.
For example, when graphite is added to the above-mentioned negative electrode substrate, the graphite functions as an electric conduction network in the negative electrode substrate, and the charge-discharge effect of the coke in the negative electrode substrate can be increased by the current collecting effect. In addition, graphite itself can also store lithium ions and function as a negative electrode substrate, so that the charge / discharge capacity can be further increased as compared with the case where boron is added only to coke.
【００１８】次に，上記コークスは，石油又は石炭の生
コークスを５００〜９００℃にて加熱することにより得
られた熱処理コークスよりなることが好ましい。上記生
コークスとしては，例えば，石油系重質油を５００℃前
後の温度において一定時間乾留（空気を絶って加熱）す
ることにより，熱分解重合反応が進行し，ガス，液状留
分と共に得られた石油生コークスを用いることができ
る。また，上記生コークスとしては，石炭を５００℃前
後の温度において乾留したものを用いることができる。Next, the coke is preferably made of a heat-treated coke obtained by heating raw coke of petroleum or coal at 500 to 900 ° C. As the raw coke, for example, the pyrolysis polymerization reaction proceeds by dry-distilling petroleum heavy oil at a temperature of about 500 ° C. for a certain time (without air), and is obtained together with gas and liquid fractions. Oily raw coke can be used. Further, as the raw coke, coal obtained by carbonizing coal at a temperature of about 500 ° C. can be used.
【００１９】上記熱処理温度が５００℃未満である場合
には，熱処理コークスの導電率が小さくなり，電極のＩ
Ｒドロップにより開路電圧に比べ閉路電圧（端子電圧）
が低下するという現象が生じ，その結果リチウム二次電
池における充放電が不十分となるおそれがある。なお，
上記ＩＲドロップとは，炭素電極中を電流が流れる場合
に生じる電圧降下のことを言う。When the heat treatment temperature is lower than 500 ° C., the conductivity of the heat-treated coke decreases, and the I
Closed voltage (terminal voltage) compared to open circuit voltage due to R drop
Occurs, and as a result, charging and discharging of the lithium secondary battery may be insufficient. In addition,
The IR drop refers to a voltage drop generated when a current flows through the carbon electrode.
【００２０】また，上記熱処理温度が９００℃を越えた
場合には，上記熱処理コークス中の水素原子と炭素原子
との原子比Ｈ／Ｃが０．１よりも小さくなり，充電時に
各炭素結晶子の末端間のキャビティ（図１参照）におい
て生成するリチウムクラスターの量が少なくなるおそれ
がある。When the heat treatment temperature exceeds 900 ° C., the atomic ratio H / C between hydrogen atoms and carbon atoms in the heat treated coke becomes smaller than 0.1, and each carbon crystallite is charged during charging. There is a possibility that the amount of lithium clusters generated in the cavity (see FIG. 1) between the ends of the metal may be reduced.
【００２１】更に，好ましい熱処理の温度の下限は６０
０℃，更に好ましい温度の上限は８００℃である。ま
た，熱処理の好ましい時間は特に限定されない。その中
でも，３０分間〜３時間の範囲内が，充放電容量が非常
に大きなものが得られるため，特に好ましい。Further, the lower limit of the preferable heat treatment temperature is 60.
The upper limit of the temperature is 0 ° C., more preferably 800 ° C. Further, the preferable time of the heat treatment is not particularly limited. Among them, a range of 30 minutes to 3 hours is particularly preferable because a very large charge / discharge capacity can be obtained.
【００２２】また，上記加熱は不活性雰囲気中で行うこ
とが好ましい。これにより，生コークスの酸化を防止す
ることができ，後述の図１に示すごとく，コークス結晶
子よりなる熱処理コークスを得ることができる。なお，
上記不活性雰囲気としては，例えば，真空雰囲気，希ガ
ス，Ｎ2 等よりなる雰囲気等を挙げることができる。The heating is preferably performed in an inert atmosphere. Thereby, oxidation of the raw coke can be prevented, and as shown in FIG. 1 described later, a heat-treated coke composed of coke crystallites can be obtained. In addition,
Examples of the inert atmosphere include a vacuum atmosphere, an atmosphere composed of a rare gas, N 2, and the like.
【００２３】上記熱処理コークスは，後述の図１に示す
ごときコークス結晶子よりなる。上記コークス結晶子
は，原料となった生コークスにおけるコークス結晶子と
比較して大きくなるが，通常のコークス（１２００〜１
４００℃で製造）に比べ，コークス結晶子の末端が増加
した状態となり，該末端間に多数のキャビティが形成さ
れた状態になる。The heat-treated coke is composed of coke crystallites as shown in FIG. The above coke crystallites are larger than the coke crystallites in raw coke used as a raw material.
(Manufactured at 400 ° C.), the end of the coke crystallites is in an increased state, and many cavities are formed between the ends.
【００２４】なお，上記コークス結晶子とは，主として
炭化水素よりなり，六員環網状平面構造を有するという
もので，その一部は結晶状の黒鉛と同様の層状構造を有
している。また，上記コークス結晶子の末端は炭素に対
し，水素が結合した状態となっている。The above-mentioned coke crystallites are mainly composed of hydrocarbons and have a six-membered ring network planar structure, and a part of them has the same layer structure as crystalline graphite. The end of the coke crystallite is in a state where hydrogen is bonded to carbon.
【００２５】そして，上記コークス結晶子において，リ
チウムイオンは，上記結晶状の黒鉛と同様の層状構造に
おける層間に対して，リチウムイオンの状態のまま吸蔵
される。また，上記コークス結晶子の末端間に形成され
たキャビティに対しても，リチウムイオンはリチウムク
ラスターを形成しつつ吸蔵される。このため，より多く
のリチウムイオン及びリチウムクラスターを吸蔵するこ
とができる。In the coke crystallite, lithium ions are occluded in the state of lithium ions between layers in the same layered structure as the crystalline graphite. Further, lithium ions are absorbed into the cavities formed between the ends of the coke crystallites while forming lithium clusters. Therefore, more lithium ions and lithium clusters can be stored.
【００２６】また，上記熱処理コークスにおいては，従
来使用されていた通常のコークス等よりも更にコークス
結晶子が小さくなり，その数が増大しているため，上記
キャビティの数，容積は，これらのものよりも増大して
いる。従って，更により多くのリチウムクラスターを吸
蔵することができる。なお，上記リチウムクラスターと
は，リチウムイオン間の相互作用により該イオンが集合
し，ひとつの塊となった状態を示している。In the above-mentioned heat-treated coke, the coke crystallites are smaller and the number of coke crystallites is larger than that of conventionally used coke and the like. More than that. Therefore, even more lithium clusters can be stored. The above-mentioned lithium cluster indicates a state in which lithium ions are aggregated by an interaction between lithium ions to form one lump.
【００２７】次に，上記熱処理コークス中の水素原子と
炭素原子との原子比Ｈ／Ｃの値は，０．１以上であるこ
とが好ましい。上記原子比Ｈ／Ｃの値の増大は，コーク
ス結晶子の末端の増加に対応しており，コークス結晶子
の末端が増大することは，該末端間に形成されたキャビ
ティが増大することを表している。Next, the value of the atomic ratio H / C of hydrogen atoms to carbon atoms in the heat-treated coke is preferably 0.1 or more. The increase in the value of the atomic ratio H / C corresponds to the increase in the terminal of the coke crystallite, and the increase in the terminal of the coke crystallite indicates that the cavity formed between the terminals increases. ing.
【００２８】以上により，リチウムクラスターが生成す
ることができるキャビティの数及び容積が増大するた
め，負極基体においてより多くのリチウムイオンが吸蔵
可能となる。このため，充放電容量の大きなリチウム二
次電池を得ることができる。上記原子比Ｈ／Ｃの値が
０．１未満である場合には，キャビティの数も容積も少
なく，充放電容量の小さなリチウム二次電池しか得られ
なくなるおそれがある。As described above, since the number and volume of cavities in which lithium clusters can be generated increase, more lithium ions can be stored in the negative electrode substrate. Therefore, a lithium secondary battery having a large charge / discharge capacity can be obtained. If the value of the atomic ratio H / C is less than 0.1, the number of cavities and the volume are small, and only a lithium secondary battery with a small charge / discharge capacity may be obtained.
【００２９】なお，上記原子比Ｈ／Ｃの上限は０．３で
あることが好ましい。原子比Ｈ／Ｃの値が，上記上限を
越えた場合には，熱処理コークスの抵抗が増大し，導電
率が１０-7Ｓｃｍ-1未満となり，ＩＲドロップにより充
分に充放電ができなくなるおそれがある。The upper limit of the atomic ratio H / C is preferably 0.3. When the value of the atomic ratio H / C exceeds the above upper limit, the resistance of the heat-treated coke increases, the conductivity becomes less than 10 −7 Scm −1, and there is a possibility that the charge and discharge cannot be sufficiently performed due to the IR drop. is there.
【００３０】次に，上記熱処理コークスは導電率が１０
-7Ｓｃｍ-1以上であることが好ましい。上記導電率が１
０-7Ｓｃｍ-1未満である場合には，キャビティの数も容
積も少なく，充放電容量の小さなリチウム二次電池しか
得られなくなるおそれがある。なお，上記導電率の上限
は１０-2Ｓｃｍ-1であることが好ましい。上記導電率が
上記上限を越えた場合には，Ｈ／Ｃが０．１以下となり
キャビティの数も容積も減少するおそれがある。Next, the above-mentioned heat-treated coke has a conductivity of 10%.
It is preferably at least -7 Scm -1 . The conductivity is 1
If it is less than 0 -7 Scm -1 , the number of cavities and the volume are small, and only a lithium secondary battery with a small charge / discharge capacity may be obtained. The upper limit of the conductivity is preferably 10 −2 Scm −1 . If the conductivity exceeds the upper limit, the H / C becomes 0.1 or less, and the number of cavities and the volume may decrease.
【００３１】[0031]
実施形態例１ 本発明の実施形態例にかかるリチウム二次電池用負極及
びその製造方法につき，図１，図２を用いて説明する。
本例のリチウム二次電池用負極は，負極基体にリチウム
を含有させてなるリチウム二次電池用負極であって，上
記負極基体はコークスとホウ素とよりなり，該ホウ素の
添加量が上記コークスと上記ホウ素との合計量に対して
０．１〜５ｗｔ％の範囲内にある。そして，上記コーク
スは，石油又は石炭の生コークスを５００〜９００℃に
て加熱することにより得られた熱処理コークスよりな
る。Embodiment 1 A negative electrode for a lithium secondary battery and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS.
The negative electrode for a lithium secondary battery of this example is a negative electrode for a lithium secondary battery in which lithium is contained in a negative electrode substrate, wherein the negative electrode substrate is composed of coke and boron. It is in the range of 0.1 to 5 wt% with respect to the total amount of boron. The coke is a heat-treated coke obtained by heating raw coke of petroleum or coal at 500 to 900 ° C.
【００３２】また，上記リチウム二次電池用負極は，例
えば以下に示すごとく製造する。すなわち，実施形態例
２において詳述するように，石油又は石炭の生コークス
にホウ素を０．１〜５ｗｔ％添加したものを５００〜９
００℃にて加熱し，熱処理コークスとなし，負極基体を
得る。次に，この負極基体にリチウムイオンを吸蔵さ
せ，リチウム二次電池用負極となす。なお，詳細は実施
形態例２において説明する。The negative electrode for a lithium secondary battery is manufactured, for example, as follows. That is, as described in detail in the second embodiment, raw coke of petroleum or coal added with 0.1 to 5 wt% of boron is added to 500 to 9 wt%.
Heat at 00 ° C. to form heat-treated coke to obtain a negative electrode substrate. Next, lithium ions are occluded in the negative electrode substrate to form a negative electrode for a lithium secondary battery. Details will be described in a second embodiment.
【００３３】本例にかかる作用効果につき以下に説明す
る。本例にかかる負極基体は，コークスとホウ素とより
なり，両者に対するホウ素の添加量は上記範囲にある。
これにより，負極基体の導電率は，コークスのみにより
構成された場合と比較して高くなる。The operation and effect of this embodiment will be described below. The negative electrode substrate according to this example is composed of coke and boron, and the amount of boron added to both is in the above range.
As a result, the conductivity of the negative electrode substrate is higher than that of the case where only the coke is used.
【００３４】また，本例にかかるコークスは熱処理コー
クスよりなる。図１に示すごとく，上記熱処理コークス
１は，生コークスを構成するコークス結晶子が，熱によ
りその一部が分解，生成した，より大きなコークス結晶
子１０より構成されている。上記リチウム二次電池用負
極においてリチウムイオンは，以下に示すごとく上記熱
処理コークス１に対し吸蔵される。The coke according to the present embodiment is made of heat-treated coke. As shown in FIG. 1, the heat-treated coke 1 is composed of larger coke crystallites 10 in which coke crystallites constituting raw coke are partially decomposed and generated by heat. In the negative electrode for a lithium secondary battery, lithium ions are occluded in the heat-treated coke 1 as described below.
【００３５】つまり，上記コークス結晶子１０はその一
部に黒鉛と同様の層状構造を有し，該層状構造における
層間１３にはリチウムイオン２がそのままインターカレ
ーションされる。そして，上記コークス結晶子１０の末
端１２と他のコークス結晶子１０の末端１２との間には
キャビティ１１が形成され，該キャビティ１１には，上
記リチウムイオン２より生成したリチウムクラスター２
０が吸蔵される。That is, the coke crystallite 10 partially has a layered structure similar to graphite, and lithium ions 2 are directly intercalated between the layers 13 in the layered structure. Then, a cavity 11 is formed between the terminal 12 of the coke crystallite 10 and the terminal 12 of another coke crystallite 10, and the lithium cluster 2 formed from the lithium ions 2 is formed in the cavity 11.
0 is stored.
【００３６】そして，上記ホウ素は，上記のごとく，負
の電荷を帯び易いため，ホウ素の添加によってドナーサ
イトがコークス内に多数形成される。そして，このドナ
ーサイトがリチウムイオンの吸着サイトとなり，リチウ
ムイオンの吸蔵量が増大すると考えられる。このため，
より多くのリチウムイオンを吸蔵することができ，よっ
て，より高い充放電容量を有するリチウム二次電池用負
極を得ることができる。[0036] As described above, boron is easily charged with a negative charge as described above, so that a large number of donor sites are formed in coke by the addition of boron. Then, it is considered that this donor site becomes an adsorption site for lithium ions, and the amount of occluded lithium ions increases. For this reason,
A larger amount of lithium ions can be stored, and thus a negative electrode for a lithium secondary battery having a higher charge / discharge capacity can be obtained.
【００３７】実施形態例２ 次に，本発明にかかるリチウム二次電池用負極の性能に
つき，図２，図３を用いて説明する。まず，試料である
負極基体の製造方法について説明する。石油系重質油を
５００℃において熱分解反応させ，生コークスとした。
その後，上記生コークスを平均粒径１２μｍに粉砕し，
粒子状の生コークスを得た。Second Embodiment Next, the performance of the negative electrode for a lithium secondary battery according to the present invention will be described with reference to FIGS. First, a method for manufacturing a negative electrode substrate as a sample will be described. The heavy petroleum oil was subjected to a thermal decomposition reaction at 500 ° C. to obtain raw coke.
Then, the raw coke was pulverized to an average particle size of 12 μm,
A particulate raw coke was obtained.
【００３８】上記粒子状の生コークスにホウ酸を，ホウ
素含有量で０〜５ｗｔ％になるように添加し，次にこれ
らをアルミナボートに乗せ，電気炉中において，アルゴ
ン流量１リットル／ｍｉｎ，昇温速度２０℃／ｍｉｎ，
到達温度９００℃，保持時間１時間にて，熱処理し，熱
処理コークスを得た。上記熱処理コークスを冷却した
後，乳鉢で粉砕して負極基体とした。Boric acid is added to the above particulate raw coke so as to have a boron content of 0 to 5% by weight, and then these are put on an alumina boat, and in an electric furnace, an argon flow rate of 1 liter / min. Heating rate 20 ° C / min,
Heat treatment was performed at an ultimate temperature of 900 ° C. and a holding time of 1 hour to obtain a heat-treated coke. After cooling the heat-treated coke, it was pulverized in a mortar to obtain a negative electrode substrate.
【００３９】次に，上記試料に対して，結着剤（ポリテ
トラフルオロエチレン粒子）を，９６：４の重量比で混
合し，乳鉢で混練後，圧縮成形機を用いて集電体（ＳＵ
Ｓメッシュ）上にプレス成形し，板状のリチウム二次電
池用負極を製作した。そして，該リチウム二次電池用負
極を炭素電極として用いたテストセルの製作につき説明
する。このテストセルにおいて，充放電容量を測定，評
価する。上記テストセル３０は，図２に示すごとく，セ
パレータ３を中心に，該セパレータ３を挟むように一対
の電解液４が配置され，更にその周囲に本発明にかかる
負極基体を用いた炭素電極６と，これに対向する対極５
及び集電体７とが配置されたものである。また，両側の
集電体７は充放電装置８に接続されている。Next, a binder (polytetrafluoroethylene particles) was mixed with the above sample in a weight ratio of 96: 4, kneaded in a mortar, and then mixed with a current collector (SU) using a compression molding machine.
(S mesh) to produce a plate-shaped negative electrode for a lithium secondary battery. The production of a test cell using the negative electrode for a lithium secondary battery as a carbon electrode will be described. In this test cell, the charge / discharge capacity is measured and evaluated. As shown in FIG. 2, the test cell 30 includes a pair of electrolytes 4 arranged around the separator 3 so as to sandwich the separator 3 and a carbon electrode 6 using the negative electrode substrate according to the present invention around the pair. And the counter electrode 5 facing this
And the current collector 7. The current collectors 7 on both sides are connected to a charging / discharging device 8.
【００４０】上記テストセル３０にかかる対極５は，直
径１５ｍｍ，厚さ０．８ｍｍのタブレット状のリチウム
金属よりなる。上記炭素電極６は，上記負極基体である
試料の９６ｗｔ％に対し，結着剤のポリテトラフルオロ
エチレン（ＰＴＦＥ）を４ｗｔ％混合した混合物２０ｍ
ｇを，集電体７となるＳＵＳ３０４メッシュと共に直径
１５ｍｍに成形したタブレットである。The counter electrode 5 of the test cell 30 is made of a tablet-shaped lithium metal having a diameter of 15 mm and a thickness of 0.8 mm. The carbon electrode 6 is composed of a 20 m mixture of 4 wt% of polytetrafluoroethylene (PTFE) as a binder with respect to 96 wt% of the sample serving as the negative electrode substrate.
g was formed into a tablet having a diameter of 15 mm together with a SUS304 mesh serving as the current collector 7.
【００４１】また，上記炭素電極６と対極５との間に設
けたセパレータ３は，多孔質ポリエチレンよりなり，そ
の大きさは直径２０ｍｍ，厚さ７５μｍとした。また，
上記テストセル３０に用いた電解液４はエチレンカーボ
ネートとジエチルカーボネート（ＥＣ／ＤＥＣ）との混
合溶液（容量比にして１対１）に，ＬｉＰＦ6 を１ｍｏ
ｌ／リットルの割合で溶解したものを使用した。The separator 3 provided between the carbon electrode 6 and the counter electrode 5 was made of porous polyethylene and had a diameter of 20 mm and a thickness of 75 μm. Also,
The electrolytic solution 4 used in the test cell 30 is a mixed solution of ethylene carbonate and diethyl carbonate (EC / DEC) (1: 1 in volume ratio) and 1 mol of LiPF 6 .
What was dissolved at a rate of 1 / liter was used.
【００４２】上記テストセル３０における充放電の試験
により，該テストセル３０の充放電容量を測定した。ま
ず，上記テストセル３０を充電するに当たっては，０．
５ｍＡ／ｃｍ2 の定電流下で０Ｖまで充電した。放電
は，１ｍＡ／ｃｍ2 で行い，テストセル３０の電池電圧
が１．５Ｖを越えた時点で終了とした。The charge / discharge capacity of the test cell 30 was measured by the charge / discharge test in the test cell 30 described above. First, when charging the test cell 30, the test cell 30 is charged with 0.1.
The battery was charged to 0 V under a constant current of 5 mA / cm 2 . The discharge was performed at 1 mA / cm 2 , and the test was terminated when the battery voltage of the test cell 30 exceeded 1.5 V.
【００４３】なお，以上の試験において，充電により炭
素電極６の電位が約１．５Ｖから０Ｖに変化するまで流
れた電気量から充電容量を，一方放電により電極電位が
０Ｖから１．５Ｖに変化するまで流れた電気量から放電
容量を求めた。一方，比較のために，黒鉛を３０ｗｔ％
添加したコークス，ポリパラフェニレン（樹脂炭１）お
よびジフェニルジアセチレン重合体（樹脂炭２）を炭素
化したもの，および黒鉛を，それぞれ負極基体としたリ
チウム二次電池についても，同様に測定した。In the above test, the charge capacity was calculated from the amount of electricity that flowed until the potential of the carbon electrode 6 changed from about 1.5 V to 0 V by charging, while the electrode potential changed from 0 V to 1.5 V by discharging. The discharge capacity was determined from the amount of electricity flowing until the discharge. On the other hand, for comparison, 30 wt% of graphite was used.
The same measurement was performed for a lithium secondary battery in which the added coke, polyparaphenylene (resin charcoal 1) and diphenyldiacetylene polymer (resin charcoal 2) were carbonized, and graphite was used as a negative electrode substrate.
【００４４】以上の結果を図３に示した。図３は，横軸
にホウ素添加量（ｗｔ％）を，縦軸に放電容量（ｍＡｈ
／ｇ）をとって，上記各負極基体を用いた場合について
示したものである。図３より知られるごとく，本発明に
かかるホウ素０．１〜５ｗｔ％の範囲内にある負極基体
は，コークスのみのものに比べ，より多くのリチウムイ
オン及びこれよりなるリチウムクラスターを吸蔵できる
ことが分かった。また，コークスのみよりなる負極基体
を用いた電極は吸蔵可能なリチウムイオンの量が，本発
明にかかる試料より劣っていることが分かった。The above results are shown in FIG. In FIG. 3, the horizontal axis represents the amount of boron added (wt%), and the vertical axis represents the discharge capacity (mAh).
/ G), and shows the case where each of the above-described negative electrode substrates is used. As can be seen from FIG. 3, the negative electrode substrate according to the present invention having a boron content in the range of 0.1 to 5 wt% can store more lithium ions and lithium clusters composed of the same than the coke alone. Was. In addition, it was found that the electrode using the negative electrode substrate consisting of only coke was inferior in the amount of lithium ions that could be stored as compared with the sample according to the present invention.
【００４５】更に，コークスのみよりなる負極基体を用
いた電極，またホウ素の量が５ｗｔ％を越えた負極基体
よりなる電極，また樹脂を炭素化した電極，及び黒鉛に
ホウ素を添加した電極は，充放電容量が低く，本発明に
かかる試料より劣っていることが分かった。Further, an electrode using a negative electrode substrate composed of only coke, an electrode composed of a negative electrode substrate having an amount of boron exceeding 5 wt%, an electrode obtained by carbonizing a resin, and an electrode obtained by adding boron to graphite are: It was found that the charge / discharge capacity was low and inferior to the sample according to the present invention.
【００４６】また，コークスに黒鉛を添加して集電効果
を高めた電極では，ホウ素無添加の場合の放電容量，ホ
ウ素を添加した場合の放電容量が共に大きくなることが
分かった。以上により，本発明にかかる負極基体よりな
る負極を有するリチウム二次電池は，より大きな充放電
容量を有することが分かった。It was also found that in the electrode in which the current collecting effect was enhanced by adding graphite to coke, the discharge capacity when boron was not added and the discharge capacity when boron was added were both increased. From the above, it was found that the lithium secondary battery having the negative electrode composed of the negative electrode substrate according to the present invention had a larger charge / discharge capacity.
【００４７】[0047]
【発明の効果】上記のごとく，本発明によれば，充放電
容量の大きなリチウム二次電池を得ることができる，リ
チウム二次電池用負極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 negative electrode for a lithium secondary battery capable of obtaining a lithium secondary battery having a large charge / discharge capacity.
【図１】実施形態例１にかかる，負極基体中の熱処理コ
ークスにリチウムイオン及びリチウムクラスターが吸蔵
された状態の説明図。FIG. 1 is an explanatory view of a state where lithium ions and lithium clusters are occluded in heat-treated coke in a negative electrode substrate according to Embodiment 1.
【図２】実施形態例２にかかる，テストセルの断面説明
図。FIG. 2 is an explanatory cross-sectional view of a test cell according to a second embodiment.
【図３】実施形態例２にかかる，ホウ素添加量と放電容
量との関係を示す線図。FIG. 3 is a diagram showing a relationship between a boron addition amount and a discharge capacity according to a second embodiment.
１．．．熱処理コークス， １０．．．コークス結晶子， ２．．．リチウムイオン， 1. . . 9. heat-treated coke, . . 1. coke crystallite; . . lithium ion,
Claims (1)
チウム二次電池用負極であって，上記負極基体はコーク
スとホウ素とよりなり，該ホウ素の添加量は，上記コー
クスと上記ホウ素との合計量（１００ｗｔ％）に対して
０．１〜５ｗｔ％であることを特徴とするリチウム二次
電池用負極。1. A negative electrode for a lithium secondary battery in which lithium is occluded in a negative electrode substrate, wherein the negative electrode substrate comprises coke and boron, and the added amount of boron is a sum of the coke and the boron. A negative electrode for a lithium secondary battery, wherein the amount is 0.1 to 5% by weight based on the amount (100% by weight).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8355336A JPH10188958A (en) | 1996-12-21 | 1996-12-21 | Negative electrode for lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8355336A JPH10188958A (en) | 1996-12-21 | 1996-12-21 | Negative electrode for lithium secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10188958A true JPH10188958A (en) | 1998-07-21 |
Family
ID=18443351
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8355336A Pending JPH10188958A (en) | 1996-12-21 | 1996-12-21 | Negative electrode for lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10188958A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001357885A (en) * | 2000-06-13 | 2001-12-26 | Toyota Central Res & Dev Lab Inc | Lithium secondary battery |
| WO2016157508A1 (en) * | 2015-03-27 | 2016-10-06 | Nec Corporation | Boron-doped activated carbon material |
| US10714752B2 (en) | 2016-01-13 | 2020-07-14 | Nec Corporation | Hierarchical oxygen containing carbon anode for lithium ion batteries with high capacity and fast charging capability |
-
1996
- 1996-12-21 JP JP8355336A patent/JPH10188958A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001357885A (en) * | 2000-06-13 | 2001-12-26 | Toyota Central Res & Dev Lab Inc | Lithium secondary battery |
| JP4547587B2 (en) * | 2000-06-13 | 2010-09-22 | 株式会社豊田中央研究所 | Lithium secondary battery |
| WO2016157508A1 (en) * | 2015-03-27 | 2016-10-06 | Nec Corporation | Boron-doped activated carbon material |
| US10714752B2 (en) | 2016-01-13 | 2020-07-14 | Nec Corporation | Hierarchical oxygen containing carbon anode for lithium ion batteries with high capacity and fast charging capability |
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