JPH10275615A - Negative electrode for lithium ion secondary battery - Google Patents
Negative electrode for lithium ion secondary batteryInfo
- Publication number
- JPH10275615A JPH10275615A JP9079394A JP7939497A JPH10275615A JP H10275615 A JPH10275615 A JP H10275615A JP 9079394 A JP9079394 A JP 9079394A JP 7939497 A JP7939497 A JP 7939497A JP H10275615 A JPH10275615 A JP H10275615A
- Authority
- JP
- Japan
- Prior art keywords
- porous carbon
- negative electrode
- natural graphite
- carbon powder
- lithium ion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、リチウムイオンを
挿入脱離することのできる天然黒鉛を活物質とするリチ
ウムイオン二次電池用負極に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode for a lithium ion secondary battery using natural graphite as an active material into which lithium ions can be inserted and desorbed.
【０００２】[0002]
【従来の技術】リチウムイオン二次電池は、リチウムイ
オンを挿入脱離することのできる炭素材料からなる負極
と、リチウムイオンを挿入脱離することのできるリチウ
ム化合物からなる正極と、リチウムイオン導電性の非水
電解液を主要要素として構成された電池であるが、高電
圧・高エネルギー密度であることから、近年その需要が
拡大している。2. Description of the Related Art A lithium ion secondary battery comprises a negative electrode made of a carbon material into which lithium ions can be inserted and desorbed, a positive electrode made of a lithium compound into which lithium ions can be inserted and desorbed, and a lithium ion conductive material. These batteries are composed of a non-aqueous electrolyte as a main component, but their demand has been increasing in recent years because of their high voltage and high energy density.
【０００３】このようなリチウムイオン二次電池の負極
活物質としては、人造黒鉛や難黒鉛化炭素、或いは天然
黒鉛などの炭素材料が使用されている。このうち天然黒
鉛は、結晶性が高く結晶構造の規則性がよいので、人造
黒鉛や難黒鉛化炭素に比較し、電位の平坦性やハイレー
ト放電特性に優れる。しかし、天然黒鉛は、結晶性が高
い分、人造黒鉛や難黒鉛化炭素に比べ比表面積が小さい
ので、電解液の保持能力（保持量）が小さい。このた
め、ハイレート放電に際して電解液不足を起こし、イオ
ン導電の円滑が阻害される。よって、天然黒鉛を用いた
従来負極では、結果的に十分なハイレート放電特性が得
られていない。[0003] As a negative electrode active material of such a lithium ion secondary battery, a carbon material such as artificial graphite, non-graphitizable carbon, or natural graphite is used. Among them, natural graphite has high crystallinity and good regularity of the crystal structure, and therefore has excellent potential flatness and high-rate discharge characteristics as compared with artificial graphite and non-graphitizable carbon. However, natural graphite has a small specific surface area as compared with artificial graphite and non-graphitizable carbon because of its high crystallinity, and therefore has a low ability to retain an electrolytic solution (retention amount). For this reason, electrolyte shortage occurs at the time of high-rate discharge, and the smoothness of ionic conduction is hindered. Therefore, in the conventional negative electrode using natural graphite, sufficient high-rate discharge characteristics cannot be obtained as a result.
【０００４】また、天然黒鉛は、人造黒鉛や難黒鉛化炭
素に比べ、自己滑沢性や劈開性が強いので、集電体等に
対する結着力が弱くなる。このため、天然黒鉛を用いた
負極は、黒鉛が充放電の度に膨張収縮することもあっ
て、充放電サイクルの進行と共に活物質層と集電体との
密着性が劣化する。密着性の劣化は集電効率の低下や活
物質の脱落を招くので、天然黒鉛を用いた負極では、十
分なサイクル寿命が得られにくい。[0004] Natural graphite has a stronger self-lubricating property and cleavage property than artificial graphite or non-graphitizable carbon, and therefore has a weaker binding force to a current collector or the like. For this reason, in the negative electrode using natural graphite, the adhesion between the active material layer and the current collector deteriorates as the charge / discharge cycle progresses, because the graphite expands and contracts each time charge / discharge occurs. Deterioration of adhesion results in lowering of current collection efficiency and dropping of active material, and thus it is difficult to obtain sufficient cycle life with a negative electrode using natural graphite.
【０００５】このように天然黒鉛は、リチウムイオンの
挿入脱離の点では極めて優れた能力を有するが、自己滑
沢性や劈開性が強く、また電解液保持力が小さいという
短所を有しており、従来の技術では、この天然黒鉛の持
つ短所を十分に制御できていなかった。[0005] As described above, natural graphite has an extremely excellent ability in terms of insertion and desorption of lithium ions, but has the disadvantages of strong self-lubricating properties and cleaving properties and low electrolyte solution holding power. In addition, the conventional technology has not been able to sufficiently control the disadvantages of the natural graphite.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、上記に鑑
み、天然黒鉛の持つ上記短所を制御し、天然黒鉛の持つ
優れた能力を十分に引き出すことにより、高電圧・高エ
ネルギー密度でサイクル特性、ハイレート放電特性にも
優れたリチウムイオン二次電池用負極を提供することを
目的とする。SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to control the above-mentioned disadvantages of natural graphite and to fully exploit the superior capabilities of natural graphite to achieve high voltage, high energy density and cycle characteristics. It is another object of the present invention to provide a negative electrode for a lithium ion secondary battery having excellent high-rate discharge characteristics.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するため
に、本発明は次のように構成される。To achieve the above object, the present invention is configured as follows.
【０００８】請求項１記載の発明は、負極活物質として
の天然黒鉛と、添加剤としての多孔質炭素粉末と、結着
剤とを含み構成されたリチウムイオン二次電池用負極で
ある。The first aspect of the present invention is a negative electrode for a lithium ion secondary battery comprising natural graphite as a negative electrode active material, porous carbon powder as an additive, and a binder.
【０００９】この構成であると、天然黒鉛と共に添加さ
れた多孔質炭素粉末が、電解液を保持できるので、リチ
ウムイオンの挿入脱離に際し必要な電解液を反応サイト
に供給する。よって、天然黒鉛の持つハイレート放電能
力が、電解液不足によって制限されてしまうことがな
い。また、天然黒鉛の近傍にある多孔質炭素粉末が、結
着剤と共働して天然黒鉛を集電体に強力に結着するよう
に作用し、天然黒鉛の集電体に対する密着性を高める。
これにより、集電効率が向上すると共に、天然黒鉛負極
のサイクル特性が向上する。According to this structure, the porous carbon powder added together with the natural graphite can hold the electrolytic solution, so that the electrolytic solution necessary for insertion and desorption of lithium ions is supplied to the reaction site. Therefore, the high-rate discharge capability of natural graphite is not limited by lack of electrolyte. In addition, the porous carbon powder in the vicinity of the natural graphite acts in cooperation with the binder to strongly bind the natural graphite to the current collector, and enhances the adhesion of the natural graphite to the current collector. .
This improves the current collection efficiency and improves the cycle characteristics of the natural graphite negative electrode.
【００１０】請求項２記載の発明は、請求項１記載のリ
チウムイオン二次電池用負極において、前記多孔質炭素
粉末の比表面積が、３０ｍ2 ／ｇ以上であることを特徴
とする。A second aspect of the present invention is the negative electrode for a lithium ion secondary battery according to the first aspect, wherein the specific surface area of the porous carbon powder is 30 m 2 / g or more.
【００１１】この構成であると、多孔質炭素粉末の作用
により、ハイレート放電特性及びサイクル特性が確実に
向上する。With this configuration, the high-rate discharge characteristics and cycle characteristics are reliably improved by the action of the porous carbon powder.
【００１２】請求項３記載の発明は、請求項１記載のリ
チウムイオン二次電池用負極において、前記多孔質炭素
粉末の比表面積が、１３０ｍ2 ／ｇ以上であることを特
徴とする。According to a third aspect of the present invention, in the negative electrode for a lithium ion secondary battery according to the first aspect, a specific surface area of the porous carbon powder is 130 m 2 / g or more.
【００１３】１３０ｍ2 ／ｇ以上の広い比表面積を有す
る多孔質炭素であると、結着剤が付着し易いので、多孔
質炭素が結着剤と共働して天然黒鉛を集電体に強力に結
着する。よって、天然黒鉛の集電体に対する密着性が一
層高まる。また、１３０ｍ2／ｇ以上の広い比表面積を
有する多孔質炭素であると、十分な量の電解液を保持で
きるので、ハイレート放電特性が一層向上する。When the porous carbon has a large specific surface area of 130 m 2 / g or more, the binder is easily attached to the porous carbon, and the porous carbon cooperates with the binder to make natural graphite strong for the current collector. Tied to Therefore, the adhesion of the natural graphite to the current collector is further improved. In addition, when the porous carbon has a large specific surface area of 130 m 2 / g or more, a sufficient amount of the electrolyte can be held, so that the high-rate discharge characteristics are further improved.
【００１４】請求項４記載の発明は、請求項１乃至３記
載のリチウムイオン二次電池用負極において、前記多孔
質炭素粉末の平均粒径が、２０μｍ以下であることを特
徴とする。According to a fourth aspect of the present invention, in the negative electrode for a lithium ion secondary battery according to any one of the first to third aspects, the porous carbon powder has an average particle diameter of 20 μm or less.
【００１５】平均粒径が２０μｍ以下の多孔質炭素粉末
であると、負極活物質である天然黒鉛との混合性が良好
となる。よって、多孔質炭素粉末が天然黒鉛の近傍にあ
って、効果的に結着補強作用や電解液供給作用を発揮す
るので、負極のハイレート放電特性やサイクル特性が確
実に向上する。When the porous carbon powder has an average particle diameter of 20 μm or less, the mixing property with natural graphite as a negative electrode active material becomes good. Therefore, since the porous carbon powder is in the vicinity of the natural graphite and effectively exerts the binding reinforcing effect and the electrolytic solution supplying effect, the high-rate discharge characteristics and cycle characteristics of the negative electrode are surely improved.
【００１６】請求項５記載の発明は、請求項１乃至３記
載の記載のリチウムイオン二次電池用負極において、前
記多孔質炭素粉末の平均粒径が、１０μｍ以下であるこ
とを特徴とする。According to a fifth aspect of the present invention, in the negative electrode for a lithium ion secondary battery according to any one of the first to third aspects, the porous carbon powder has an average particle diameter of 10 μm or less.
【００１７】平均粒径１０μｍ以下の微細な多孔質炭素
であると、単位重量当たりの粒子数が多いので、天然黒
鉛の近傍には必ず多孔質炭素粉末が存在することにな
る。よって、結着力のバラツキが少なくなり、活物質層
の剥離強度が確実に高まる。In the case of fine porous carbon having an average particle diameter of 10 μm or less, the number of particles per unit weight is large, so that porous carbon powder always exists near natural graphite. Therefore, the dispersion of the binding force is reduced, and the peel strength of the active material layer is reliably increased.
【００１８】請求項６記載の発明は、請求項１乃至５記
載のリチウムイオン二次電池用負極において、前記多孔
質炭素粉末が、前記天然黒鉛に対し０．０１重量％ない
し２重量％添加されていることを特徴とする。According to a sixth aspect of the present invention, in the negative electrode for a lithium ion secondary battery according to any one of the first to fifth aspects, the porous carbon powder is added in an amount of 0.01% by weight to 2% by weight based on the natural graphite. It is characterized by having.
【００１９】この構成であると、多孔質炭素粉末を添加
しない負極に比べ、確実にハイレート放電特性及びサイ
クル特性を高めることができる。With this configuration, high-rate discharge characteristics and cycle characteristics can be surely improved as compared with a negative electrode to which no porous carbon powder is added.
【００２０】請求項７記載の発明は、請求項１乃至５記
載のリチウムイオン二次電池用負極において、前記多孔
質炭素粉末が、前記天然黒鉛に対し０．０５重量％ない
し１．０重量％添加されていることを特徴とする。According to a seventh aspect of the present invention, in the negative electrode for a lithium ion secondary battery according to any one of the first to fifth aspects, the porous carbon powder is used in an amount of 0.05% by weight to 1.0% by weight based on the natural graphite. It is characterized by being added.
【００２１】この構成であると、一層効率的にハイレー
ト放電特性及びサイクル特性を高めることができる。With this configuration, high-rate discharge characteristics and cycle characteristics can be more efficiently improved.
【００２２】[0022]
【実施の形態】本発明リチウムイオン二次電池用負極
は、活物質としての天然黒鉛と、添加剤としての多孔質
炭素粉末と、天然黒鉛と多孔質炭素粉末とを含む活物質
層を集電体に結着する結着剤とで構成されている。この
リチウムイオン二次電池は、天然黒鉛粉末と多孔質炭素
粉末と結着剤とを混合してスラリー状となし、このスラ
リーを金属箔からなる集電体の両面に塗着する公知の方
法によって作製できる。DESCRIPTION OF THE PREFERRED EMBODIMENTS The negative electrode for a lithium ion secondary battery according to the present invention collects an active material layer containing natural graphite as an active material, porous carbon powder as an additive, and natural graphite and porous carbon powder. And a binder that binds to the body. This lithium ion secondary battery is prepared by mixing natural graphite powder, porous carbon powder, and a binder to form a slurry, and applying this slurry to both sides of a current collector made of a metal foil by a known method. Can be made.
【００２３】このような本発明リチウムイオン二次電池
用負極においては、格子面（００２）面における面間隔
ｄ002 が３．３５以上、３．３６Å未満の天然黒鉛が活
物質として使用される。この天然黒鉛の平均粒径として
は、１〜５０μｍが好ましく、より好ましくは５〜３０
μｍがよい。１μｍ未満であると、反応活性な端面が増
加するため、幅反応による電池性能の低下が生じる。そ
の一方、５０μｍを越えると、均一な活物質層を集電体
上に形成することが困難だからである。In such a negative electrode for a lithium ion secondary battery of the present invention, natural graphite having a spacing d 002 of 3.35 or more and less than 3.36 ° on a lattice (002) plane is used as an active material. The average particle size of the natural graphite is preferably 1 to 50 μm, more preferably 5 to 30 μm.
μm is good. When the thickness is less than 1 μm, the reaction active end face increases, so that the battery performance decreases due to the width reaction. On the other hand, if it exceeds 50 μm, it is difficult to form a uniform active material layer on the current collector.
【００２４】また、多孔質炭素粉末としては、多数の細
孔が形成された炭素粒子が使用される。多数の細孔は、
炭素粒子の比表面積を広げるのに寄与するものである。
したがって、粒子表面で開口していなければならない
が、貫通孔である必要はない。このような多孔質炭素粉
末として、例えばアセチレンブラック、カーボンブラッ
ク、ケッチエンブラックが使用でき、これらの多孔質炭
素粉末を天然黒鉛（活物質）と結着剤と共に配合した天
然黒鉛負極は、ハイレート放電特性やサイクル特性に優
れる。As the porous carbon powder, carbon particles having a large number of pores are used. Many pores are
This contributes to increasing the specific surface area of the carbon particles.
Therefore, it must be open at the particle surface, but need not be a through hole. As such a porous carbon powder, for example, acetylene black, carbon black, and ketchen black can be used. A natural graphite negative electrode in which these porous carbon powders are blended with a natural graphite (active material) and a binder is used for a high-rate discharge. Excellent in characteristics and cycle characteristics.
【００２５】その理由は、細孔を多数有する多孔質炭素
粉末が電解液を保持し、この電解液を必要に応じ天然黒
鉛に供給するように作用する。したがって、天然黒鉛の
層間へのリチウムイオンの挿入脱離が円滑になり、ハイ
レート放電に際してもリチウムイオンが速やかに移動で
きる。よって、負極のハイレート放電特性が向上する。
また、細孔を多数有し比表面積の大きい多孔質炭素粉末
は、結着剤による結着効果が大きいので、天然黒鉛の近
傍にあって天然黒鉛を結着した状態で集電体に結着す
る。よって、天然黒鉛、多孔質炭素粉末、及び結着剤を
有してなる活物質層と負極集電体との密着性・結合性が
向上し、この結果として負極の集電効率やサイクル特性
が向上する。The reason is that the porous carbon powder having a large number of pores holds the electrolytic solution and acts to supply the electrolytic solution to natural graphite as required. Therefore, insertion and desorption of lithium ions between the layers of natural graphite are smooth, and lithium ions can move quickly even during high-rate discharge. Therefore, the high-rate discharge characteristics of the negative electrode are improved.
In addition, porous carbon powder having many pores and a large specific surface area has a large binding effect by a binder, and thus is bound to a current collector in a state where natural graphite is bound in the vicinity of natural graphite. I do. Therefore, the adhesion / bonding property between the active material layer including the natural graphite, the porous carbon powder, and the binder and the negative electrode current collector is improved, and as a result, the current collection efficiency and cycle characteristics of the negative electrode are improved. improves.
【００２６】多孔質炭素粉末は、天然黒鉛負極中にあっ
て上述のような作用効果を奏するものである。よって、
本発明で使用する多孔質炭素粉末としては、好ましくは
平均粒径が２０μｍ以下のものを用い、より好ましくは
１０μｍ以下のものを用いる。平均粒径が２０μｍを超
えるものでは、負極活物質層中における多孔質炭素粒子
の密度が過少になるので、天然黒鉛に対する電解液供給
効果及び結着補強効果が低下するからである。他方、平
均粒径が１０μｍ以下であると、負極活物質層中におけ
る多孔質炭素粒子の密度が大きくなり、天然黒鉛の近傍
に多孔質炭素粒子が存在することになるので、電解液供
給効果及び結着補強効果が一層高まるからである。The porous carbon powder is present in the natural graphite negative electrode and has the above-described effects. Therefore,
As the porous carbon powder used in the present invention, those having an average particle diameter of 20 μm or less are preferably used, and those having an average particle diameter of 10 μm or less are more preferably used. If the average particle size exceeds 20 μm, the density of the porous carbon particles in the negative electrode active material layer becomes too low, so that the effect of supplying the electrolytic solution to the natural graphite and the effect of reinforcing the binding are reduced. On the other hand, when the average particle size is 10 μm or less, the density of the porous carbon particles in the negative electrode active material layer increases, and the porous carbon particles are present in the vicinity of natural graphite. This is because the binding reinforcing effect is further enhanced.
【００２７】また、本発明で使用する多孔質炭素粉末と
しては、好ましくは比表面積が３０ｍ2 ／ｇ以上、より
好ましくは１３０ｍ2 ／ｇ以上のものを用いる。比表面
積が３０ｍ2 ／ｇ以上の多孔質炭素粉末であると、ハイ
レート放電特性、サイクル特性を確実に向上させること
ができ、比表面積が１３０ｍ2 ／ｇ以上のものである
と、上記特性を一層顕著に向上させることができるから
である。The porous carbon powder used in the present invention preferably has a specific surface area of 30 m 2 / g or more, more preferably 130 m 2 / g or more. The porous carbon powder having a specific surface area of 30 m 2 / g or more can surely improve high-rate discharge characteristics and cycle characteristics. If the specific surface area is 130 m 2 / g or more, the above characteristics can be further improved. This is because it can be significantly improved.
【００２８】上記結着剤は、活物質と多孔質炭素粉末を
集電体に結着する役割を担うものであり、この目的に適
う限り本発明においては種々の公知の結着剤が使用でき
る。例えば分子内にフッ素を含むフッ素系高分子化合物
や、熱可塑性樹脂、ゴム弾性を有する高分子化合物、合
成粘着剤、更には粘着性を有する多糖類などが使用で
き、これらの結着剤は単独で使用してもよく、２種類以
上を組み合わせて使用してもよい。The binder serves to bind the active material and the porous carbon powder to the current collector, and various known binders can be used in the present invention as long as the binder is suitable for this purpose. . For example, a fluorine-based polymer compound containing fluorine in the molecule, a thermoplastic resin, a polymer compound having rubber elasticity, a synthetic pressure-sensitive adhesive, and further a polysaccharide having tackiness can be used, and these binders are used alone. Or two or more of them may be used in combination.
【００２９】具体的には 上記分子内にフッ素を含むフ
ッ素系高分子化合物としては、例えばポリテトラフルオ
ロエチレン、ポリクロロトリフルオロエチレン、ポリフ
ッ化ビニリデン、フッ化ビニリデン−ヘキサフルオロプ
ロピレン共重合体、ポリフッ化ビニル等が例示できる。
また、熱可塑性樹脂、ゴム弾性を有する高分子化合物、
合成粘着剤としては、アクリル樹脂、ウレタン樹脂、エ
チレン−プロピレン−ジエンーモノマー（ＥＰＤＭ）、
スルホン化ＥＰＤＭ、ポリエチレン、ポリプロピレン、
スチレンプロピレンゴム、ポリブタジエン、ポリエチレ
ンオキシド、ポリビニルアルコール、ポリビニルクロリ
ド、ポリビニルピロリドンが例示できる。更に、粘着性
を有する多糖類としては、澱粉、カルボキシメチルセル
ロース、再生セルロース、ジアセチルセルロースなどが
例示できる。Specifically, the above-mentioned fluorine-containing polymer compound containing fluorine in the molecule includes, for example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and polyfluoroethylene. Vinyl chloride and the like can be exemplified.
Further, a thermoplastic resin, a polymer compound having rubber elasticity,
Acrylic resin, urethane resin, ethylene-propylene-diene-monomer (EPDM),
Sulfonated EPDM, polyethylene, polypropylene,
Examples include styrene propylene rubber, polybutadiene, polyethylene oxide, polyvinyl alcohol, polyvinyl chloride, and polyvinylpyrrolidone. Further, examples of the polysaccharide having tackiness include starch, carboxymethyl cellulose, regenerated cellulose, diacetyl cellulose and the like.
【００３０】なお、多糖類のようにリチウムと反応する
官能基を有する結着剤を用いる場合には、これと共に例
えばイソシアネート基を有する化合物などを添加するな
どして、結着剤が有する反応性官能基を失活させること
が望ましい。When a binder having a functional group which reacts with lithium, such as a polysaccharide, is used, a compound having an isocyanate group may be added together with the binder to form a reactive agent of the binder. It is desirable to deactivate the functional groups.
【００３１】負極性能の評価の部 多孔質炭素粉末の活物質に対する添加量を変え、また比
表面積の異なる多孔質炭素粉末を用いて種々の炭素負極
を作製した。そして、これらの負極を用いて試験用のリ
チウムイオン二次電池（公称容量１２５０ｍＡＨ）を作
製し、その性能を比較する手法により、本発明構成の意
義を明らかにした。 Evaluation of Negative Electrode Performance The amount of the porous carbon powder added to the active material was changed, and various carbon negative electrodes were produced using porous carbon powders having different specific surface areas . Then, a lithium ion secondary battery for testing (nominal capacity of 1250 mAH) was manufactured using these negative electrodes, and the significance of the configuration of the present invention was clarified by a method of comparing the performance.
【００３２】図８は、下記の各試験で使用したリチウム
イオン二次電池の全体構造を説明するための断面模式図
である。図８中、１はＬｉＣｏＯ2 から成る正極であ
り、２は天然黒鉛と多孔質炭素粉末を主体とする負極で
ある。更に、３は正負電極を離間するセパレータ、４は
正極リード、５は負極リード、６は正極外部端子、７は
電池缶、８は封口板、９は絶縁パッキングである。FIG. 8 is a schematic cross-sectional view for explaining the overall structure of the lithium ion secondary battery used in each of the tests described below. In FIG. 8, 1 is a positive electrode made of LiCoO 2 , and 2 is a negative electrode mainly composed of natural graphite and porous carbon powder. Further, 3 is a separator for separating the positive and negative electrodes, 4 is a positive electrode lead, 5 is a negative electrode lead, 6 is a positive electrode external terminal, 7 is a battery can, 8 is a sealing plate, and 9 is an insulating packing.
【００３３】正極１及び負極２は、セパレータ３を介し
て渦巻き状に巻き取られた状態で、電池缶７内に収容さ
れ、電池缶７内には電解液が注液されている。正極１は
正極リード４を介して正極外部端子６に接続され、負極
２は負極リード５を介して負極外部端子を兼ねる電池缶
７に接続されている。The positive electrode 1 and the negative electrode 2 are housed in a battery can 7 in a state of being spirally wound via a separator 3, and an electrolyte is injected into the battery can 7. The positive electrode 1 is connected to a positive electrode external terminal 6 via a positive electrode lead 4, and the negative electrode 2 is connected to a battery can 7 also serving as a negative electrode external terminal via a negative electrode lead 5.
【００３４】本発明にかかる負極２は、次のようにして
作製された。The negative electrode 2 according to the present invention was produced as follows.
【００３５】(1) 多孔質炭素の比表面積を変化させた負
極 格子面（００２）面における面間隔ｄ002 が３．３５以
上、３．３６Å未満の天然黒鉛粉末（平均粒子径約１０
μｍ）を負極活物質とし、この天然黒鉛粉末１００重量
部に対し、多孔質炭素粉末としてのケッチエンブラック
（比表面積；１５ｍ2 ／ｇ、３０ｍ2 ／ｇ、７０ｍ2 ／
ｇ、１３０ｍ2 ／ｇ、６００ｍ2 ／ｇ、１０００ｍ2 ／
ｇ；平均粒子径２μｍ）１．０重量部を加え、更に前記
天然黒鉛粉末９５重量部に対しＮ−メチル−２−ピロリ
ドンに溶解したポリフッ化ビニリデン（結着剤）をポリ
フッ化ビニリデンとして５重量部加え混合して、活物質
スラリーとなした。この活物質スラリーを銅箔からなる
負極集電体（電極芯体）に塗布し、しかる後２００℃で
熱処理して５又は６通りの負極を作製した。(1) Negative Electrode with Specific Surface Area of Porous Carbon A natural graphite powder having an interplanar spacing d 002 of 3.35 or more and less than 3.36 ° on the (002) plane (average particle diameter of about 10
The [mu] m) as a negative electrode active material, relative to the natural graphite powder 100 parts by weight, Ketjenblack as porous carbon powder (specific surface area; 15m 2 / g, 30m 2 / g, 70m 2 /
g, 130m 2 / g, 600m 2 / g, 1000m 2 /
g; average particle diameter of 2 μm), and 1.0 part by weight of polyvinylidene fluoride (a binder) dissolved in N-methyl-2-pyrrolidone as 95% by weight of the natural graphite powder as 5 parts by weight of polyvinylidene fluoride. The mixture was added and mixed to form an active material slurry. This active material slurry was applied to a negative electrode current collector (electrode core) made of copper foil, and then heat-treated at 200 ° C. to prepare five or six types of negative electrodes.
【００３６】なお、上記多孔質炭素粉末の比表面積は、
ＢＥＴ法で測定した値である。The specific surface area of the porous carbon powder is as follows:
This is a value measured by the BET method.
【００３７】(2) 多孔質炭素の平均粒径を変化させた負
極 多孔質炭素粉末の比表面積を１０００ｍ2 ／ｇ（共
通）、天然黒鉛に対する添加量を１．０重量％（共通）
とし、平均粒子径のみを１μｍ、２μｍ、１０μｍ、１
５μｍ、２０μｍ、２５μｍ、３０μｍにそれぞれ変化
させたこと以外は、上記と同様にして７通りの負極を作
製した。(2) Negative electrode in which the average particle size of porous carbon was changed The specific surface area of the porous carbon powder was 1000 m 2 / g (common), and the amount added to natural graphite was 1.0% by weight (common).
And only the average particle size is 1 μm, 2 μm, 10 μm, 1
Seven kinds of negative electrodes were produced in the same manner as above except that the thickness was changed to 5 μm, 20 μm, 25 μm, and 30 μm, respectively.
【００３８】(3) 多孔質炭素の添加量を変化させた負極 天然黒鉛粉末１００重量部に対し、比表面積が１０００
ｍ2 ／ｇ（共通）のケッチエンブラック（平均粒子径約
２μｍ）を 0.01 重量部、0.05重量部、 0.1重量部、1.
0 重量部、 2.0重量部、又は2.2 重量部を加えたこと以
外は、上記と同様にして５又は６通りの負極を作製し
た。(3) Negative Electrode with Added Porous Carbon The specific surface area is 1000 per 100 parts by weight of natural graphite powder.
0.01 parts by weight, 0.05 parts by weight, 0.1 parts by weight of ketchen black (average particle diameter of about 2 μm) of m 2 / g (common)
Five or six negative electrodes were prepared in the same manner as described above except that 0 parts by weight, 2.0 parts by weight, or 2.2 parts by weight was added.
【００３９】正極１は次のようにして作製した。８００
℃で熱処理したリチウム含有二酸化コバルトＬｉＣｏＯ
2 を正極材料とし、この正極材料ＬｉＣｏＯ2 と、導電
剤としてのカーボン粉末と、結着剤としてのフッ素樹脂
粉末とを、８５：１０：５の重量比で混合し、この混合
物をアルミニウム箔からなる正極集電体（電極芯体）に
塗布した後、これを１５０℃で熱処理して正極となし
た。The positive electrode 1 was manufactured as follows. 800
Lithium-containing cobalt dioxide LiCoO heat-treated at 40 ° C
2 as a positive electrode material, this positive electrode material LiCoO 2 , a carbon powder as a conductive agent, and a fluororesin powder as a binder were mixed in a weight ratio of 85: 10: 5, and this mixture was mixed with aluminum foil. After coating on the positive electrode current collector (electrode core), the resultant was heat-treated at 150 ° C. to form a positive electrode.
【００４０】電解液としては、エチレンカーボネート
と、１，２−ジメトキシエタンとを体積比１：１で混合
し、これにヘキサフルオロリン酸リチウムＬｉＰＦ6 を
１MOL/L の割合で溶解してなる非水電解液を用いた。As the electrolytic solution, ethylene carbonate and 1,2-dimethoxyethane were mixed at a volume ratio of 1: 1 and lithium hexafluorophosphate LiPF 6 was dissolved at a ratio of 1 MOL / L. A water electrolyte was used.
【００４１】セパレータ３としては、厚さ３０μｍのリ
チウムイオン透過性のポリプロピレン製の微多孔膜（ヘ
キストセラニーズ社製セルカード）を用いた。As the separator 3, a 30 μm-thick lithium-ion permeable polypropylene microporous membrane (Cell Card manufactured by Hoechst Celanese Corporation) was used.
【００４２】他方、上記天然黒鉛に代えて、格子面（０
０２）面における面間隔ｄ002 が３．３６Å以上、３．
３９Å以下の人造黒鉛を負極活物質として用い、上記と
同様な方法で比較例負極及び比較例電池を作製した。On the other hand, a lattice plane (0
02) The plane distance d 002 in the plane is 3.36 ° or more;
A negative electrode for comparative example and a battery for comparative example were produced in the same manner as described above, using artificial graphite of 39 ° or less as the negative electrode active material.
【００４３】上記で作製した各種負極について、剥離強
度試験、ハイレート放電特性試験、、サイクル特性試験
を行った。試験方法は次の通りである。A peel strength test, a high rate discharge characteristic test, and a cycle characteristic test were performed on the various negative electrodes prepared above. The test method is as follows.
【００４４】（剥離強度試験法）負極表面（活物質層）
に粘着テープを張り付け、そのテープの端をバネ秤に取
付けて引っ張り、粘着テープが負極表面から剥がれると
きの引張荷重を測定した。なお、粘着テープは、活物質
層に極めて強力に粘着するので、負極表面からの粘着テ
ープの剥がれは、集電体から活物質層の剥がれを意味す
る。(Peeling strength test method) Negative electrode surface (active material layer)
Then, an end of the tape was attached to a spring balance and pulled, and the tensile load when the adhesive tape was peeled off from the negative electrode surface was measured. Note that the pressure-sensitive adhesive tape extremely strongly adheres to the active material layer, and thus peeling of the pressure-sensitive adhesive tape from the negative electrode surface means peeling of the active material layer from the current collector.
【００４５】（ハイレート放電特性試験法）１．２５Ａ
（１Ｃ）の電流値で４．１Ｖまで充電（２０ｍＡカット
オフ充電）した後、０．２５Ａ（０．２Ｃ）の電流値で
電池電圧が２．７５Ｖとなるまで放電したときの放電容
量Ｃ1 と、２．５Ａ（２Ｃ）の電流値で電池電圧が２．
７５Ｖとなるまで放電したときの放電容量Ｃ2 を測定し
た。そして、Ｃ1 に対するＣ 2 の比を求め、この値を
（Ｃ2 ／Ｃ1 ）をハイレート放電特性値とした。(High Rate Discharge Characteristics Test Method) 1.25A
Charges up to 4.1V with (1C) current value (20mA cut)
Off charge) and then with a current value of 0.25A (0.2C)
Discharge capacity when discharged until battery voltage reaches 2.75V
Quantity C1And a battery voltage of 2.A at a current value of 2.5A (2C).
Discharge capacity C when discharged to 75VTwoMeasure
Was. And C1C for TwoAnd find this value
(CTwo/ C1) Is the high-rate discharge characteristic value.
【００４６】（サイクル特性試験法）サイクル特性試験
は、電池電圧４．１Ｖに達するまで１．２５Ａで充電
し、更に電池電圧４．１Ｖを保持したままで充電電流値
を徐々に２０ｍＡまで減じる方法で充電した後、電池電
圧が２．７５Ｖに達するまで１．２５Ａの電流値で放電
するサイクルを、２５℃で５００回繰り返すという条件
で行った。この充放電サイクルにおける初回放電容量に
対する５００サイクル後の放電容量の比率をサイクル特
性値とした。(Cycle Characteristics Test Method) In the cycle characteristics test, the battery is charged at 1.25 A until the battery voltage reaches 4.1 V, and the charging current value is gradually reduced to 20 mA while maintaining the battery voltage at 4.1 V. , And a cycle of discharging at a current value of 1.25 A until the battery voltage reaches 2.75 V was repeated 500 times at 25 ° C. The ratio of the discharge capacity after 500 cycles to the initial discharge capacity in this charge / discharge cycle was taken as the cycle characteristic value.
【００４７】試験結果を図１〜７にそれぞれ示す。以
下、図に基づいて順次説明する。The test results are shown in FIGS. Hereinafter, description will be made sequentially with reference to the drawings.
【００４８】（多孔質炭素の比表面積と集電体密着性と
の関係）図１に、天然黒鉛に対する多孔質炭素粉末の添
加量を１．０重量％（固定）とし、比表面積の異なる多
孔質炭素粉末を用いて作製した負極における剥離強度の
試験結果を示す。また図１には、多孔質炭素粉末を添加
しないで作製した天然黒鉛負極における剥離強度のレベ
ルを破線で示す。(Relationship between Specific Surface Area of Porous Carbon and Adhesion to Current Collector) FIG. 1 shows that the amount of porous carbon powder added to natural graphite was 1.0% by weight (fixed), 4 shows test results of peel strength of a negative electrode manufactured using porous carbon powder. FIG. 1 shows the level of the peel strength of the natural graphite negative electrode produced without adding the porous carbon powder by a broken line.
【００４９】図１から明らかなように、比表面積が３０
ｍ2 ／ｇ以上の多孔質炭素粉末を用いた場合において、
多孔質炭素無添加の天然黒鉛負極よりも高い剥離強度が
得られ、比表面積が１３０ｍ2 ／ｇ以上において顕著に
高い剥離強度が得られた。但し、比表面積が１０００ｍ
2 ／ｇを越えると剥離強度の増大傾向が鈍化した。この
結果から、天然黒鉛負極においては、結着剤と共に多孔
質炭素粉末を添加すると、集電体に対する結着性・密着
性が弱いという天然黒鉛の短所を改善でき、特に比表面
積が１３０ｍ2 ／ｇ以上、より好ましくは１０００ｍ2
／ｇの多孔質炭素粉末を用いると、顕著に集電体に対す
る結着性・密着性を改善できることが判る。As is apparent from FIG. 1, the specific surface area is 30
When a porous carbon powder of m 2 / g or more is used,
Peel strength higher than that of the natural graphite negative electrode without the addition of porous carbon was obtained, and remarkably high peel strength was obtained when the specific surface area was 130 m 2 / g or more. However, the specific surface area is 1000m
If it exceeds 2 / g, the tendency of the peel strength to increase slowed down. From these results, it can be seen that, in the case of a natural graphite negative electrode, when porous carbon powder is added together with a binder, the disadvantages of natural graphite, such as poor binding and adhesion to the current collector, can be improved, and in particular, the specific surface area is 130 m 2 / g or more, more preferably 1000 m 2
/ G of the porous carbon powder, it can be seen that the binding and adhesion to the current collector can be remarkably improved.
【００５０】（多孔質炭素の平均粒径と集電体密着性と
の関係）図２に多孔質炭素粉末の添加量と剥離強度の関
係を示すと共に、多孔質炭素粉末を添加しないで作製し
た天然黒鉛負極における剥離強度のレベルを破線で示
す。図２から、平均粒径２０μｍ以下の多孔質炭素を用
いた場合において、多孔質炭素無添加の負極（破線）よ
りも高い剥離強度が得られた。更に平均粒径１０μｍ以
下の多孔質炭素を用いた場合において、顕著に優れた剥
離強度が得られた。(Relationship Between Average Particle Size of Porous Carbon and Current Collector Adhesion) FIG. 2 shows the relationship between the amount of the porous carbon powder added and the peel strength, and was prepared without adding the porous carbon powder. The level of the peel strength of the natural graphite negative electrode is indicated by a broken line. FIG. 2 shows that when the porous carbon having an average particle size of 20 μm or less was used, a higher peel strength was obtained than the negative electrode (dashed line) without the addition of the porous carbon. Furthermore, when porous carbon having an average particle size of 10 μm or less was used, remarkably excellent peel strength was obtained.
【００５１】この結果から、多孔質炭素の平均粒径とし
ては、好ましくは２０μｍ以下とし、より好ましくは１
０μｍ以下とするのがよい。他方、下限については特に
規定されないが、粉砕効率や粉砕の作業性を考慮する
と、０．１μｍ以上が好ましい。From these results, it is preferable that the average particle size of the porous carbon be 20 μm or less, and more preferably 1 μm or less.
The thickness is preferably 0 μm or less. On the other hand, the lower limit is not particularly defined, but is preferably 0.1 μm or more in consideration of the pulverization efficiency and the workability of pulverization.
【００５２】（多孔質炭素の比表面積と電池特性との関
係）次に、リチウムイオン二次電池における図３、図４
の結果について説明する。図３、図４は、上記図１の試
験で使用した天然黒鉛負極を用いて構成したリチウムイ
オン二次電池のハイレート放電特性、サイクル特性を示
すものである。図３、４中、○−○は天然黒鉛を用いた
場合であり、□−□は人造黒鉛を用いた場合における結
果である。(Relationship Between Specific Surface Area of Porous Carbon and Battery Characteristics) Next, FIGS.
The result will be described. FIGS. 3 and 4 show high-rate discharge characteristics and cycle characteristics of a lithium ion secondary battery constituted by using the natural graphite negative electrode used in the test of FIG. In FIGS. 3 and 4, ○-○ shows the results when natural graphite was used, and −- □ shows the results when artificial graphite was used.
【００５３】図１、３〜４の比較において、図３、４の
グラフパターンと上記図１のグラフパターンが極めて類
似しており、比表面積が３０ｍ2 ／ｇであれば、多孔質
炭素粉末無添加の場合よりも、優れたハイレート放電特
性やサイクル特性が得られ、比表面積１３０ｍ2 ／ｇ以
上において、顕著にハイレート放電特性やサイクル特性
が改善されていた。In comparison of FIGS. 1 and 3 to 4, the graph patterns of FIGS. 3 and 4 are very similar to the graph pattern of FIG. 1, and if the specific surface area is 30 m 2 / g, no porous carbon powder is used. Excellent high-rate discharge characteristics and cycle characteristics were obtained as compared with the case of addition, and the high-rate discharge characteristics and cycle characteristics were remarkably improved at a specific surface area of 130 m 2 / g or more.
【００５４】一方、○−○と□−□の比較において、人
造黒鉛を使用した負極では、添加する多孔質炭素粉末の
比表面積を大きくしても、ハイレート放電特性やサイク
ル特性が更に向上することがなかった。On the other hand, in the comparison between ○-○ and □-□, in the negative electrode using artificial graphite, even if the specific surface area of the porous carbon powder to be added was increased, the high-rate discharge characteristics and cycle characteristics were further improved. There was no.
【００５５】上述の結果は、２方向から考察することが
できる。すなわち、多孔質炭素粉末の比表面積とハイレ
ート放電特性の関係は次のように考察できる。比表面積
の大きい多孔質炭素粉末は、比表面積の小さいものに比
べ電解液に対する保水力が大きい。したがって、比表面
積の大きい多孔質炭素粉末を添加すると、多孔質炭素粉
末がリチウムイオンの離脱に際し必要な電解液を供給で
きる。ここで、天然黒鉛は、人造黒鉛に比べ保水力が小
さく、電解液不足がハイレート放電の円滑を阻害するた
めに高いハイレート放電性能が発揮できないが、多孔質
炭素粉末を添加すると、この炭素粉末が電解液を供給す
るように作用するので、ハイレート放電特性が顕著に向
上する。これに対し、自らが電解液を保持し得る人造黒
鉛では、電解液不足がハイレート放電特性を規制する要
因になっていない。したがって、比表面積（保水力）の
大きい多孔質炭素粉末を添加したとしても、殆どハイレ
ート放電特性が向上しない。The above results can be considered from two directions. That is, the relationship between the specific surface area of the porous carbon powder and the high-rate discharge characteristics can be considered as follows. A porous carbon powder having a large specific surface area has a greater water retention capacity for an electrolytic solution than a powder having a small specific surface area. Therefore, when a porous carbon powder having a large specific surface area is added, the porous carbon powder can supply an electrolytic solution necessary for detachment of lithium ions. Here, natural graphite has a lower water retention capacity than artificial graphite, and a shortage of an electrolyte impedes smooth high-rate discharge, so that high-rate discharge performance cannot be exhibited. Since it acts to supply the electrolytic solution, the high-rate discharge characteristics are significantly improved. On the other hand, in the artificial graphite which can hold the electrolytic solution by itself, the lack of the electrolytic solution does not become a factor that restricts the high-rate discharge characteristics. Therefore, even if a porous carbon powder having a large specific surface area (water retention capacity) is added, the high-rate discharge characteristics hardly improve.
【００５６】他方、多孔質炭素粉末の比表面積とサイク
ル特性の関係については、上記と異なり次のように考え
られる。多孔質炭素粉末の比表面積が大きくなると、電
解液に対する保水力が増加すると共に、結着剤がより強
力に付着できるようにもなる。よって、結着剤が付着し
た多孔質炭素粉末が天然黒鉛粉末を抱き込んだ形で集電
体に強力に結着するので、サイクルによって集電体と活
物質層との密着性・結着性が劣化しにくい。この結果と
して、天然黒鉛負極のサイクル特性が向上する。これに
対し、人造黒鉛は天然黒鉛に比べ滑沢性や劈開性が少な
いので、天然黒鉛における場合のような効果が得られな
い。On the other hand, the relationship between the specific surface area of the porous carbon powder and the cycle characteristics is different from the above and can be considered as follows. When the specific surface area of the porous carbon powder is increased, the water retention capacity for the electrolytic solution is increased, and the binder can be more strongly attached. Therefore, the porous carbon powder to which the binder is attached strongly binds to the current collector in the form of embracing the natural graphite powder, so that the adhesion and binding properties between the current collector and the active material layer depend on the cycle. Is hardly deteriorated. As a result, the cycle characteristics of the natural graphite negative electrode are improved. On the other hand, artificial graphite has less lubricity and cleavage properties as compared with natural graphite, so that the effect as in the case of natural graphite cannot be obtained.
【００５７】（多孔質炭素の添加量と集電体密着性との
関係）図５に、比表面積１０００ｍ2 ／ｇの多孔質炭素
粉末（固定）を用い、その添加量を変化させた場合にお
ける剥離強度の試験結果を示す。また、前記図１の場合
と同様、図５中に破線で多孔質炭素粉末を添加しない負
極における剥離強度のレベルを示す。(Relationship Between Addition Amount of Porous Carbon and Adhesion to Current Collector) FIG. 5 shows a case where porous carbon powder (fixed) having a specific surface area of 1000 m 2 / g was used and the addition amount was changed. The test results of the peel strength are shown. Also, as in the case of FIG. 1, the broken line in FIG. 5 shows the peel strength level of the negative electrode to which the porous carbon powder was not added.
【００５８】図５において、多孔質炭素粉末の添加量が
０．０５重量％を越えると、剥離強度の改善が認められ
るようになり、０．１重量％以上で顕著に剥離強度が改
善された。但し、１重量％を越えると次第に改善程度が
鈍化し、２重量％を越えて増量しても効果が少ないこと
が確認できた。In FIG. 5, when the added amount of the porous carbon powder exceeds 0.05% by weight, the peel strength is improved, and when it is 0.1% by weight or more, the peel strength is remarkably improved. . However, it was confirmed that when the content exceeded 1% by weight, the degree of improvement gradually decreased, and even when the content exceeded 2% by weight, the effect was small.
【００５９】（多孔質炭素の添加量と電池特性との関
係）図６、７の結果に基づいて多孔質炭素の添加量とハ
イレート放電特性及びサイクル特性の関係について説明
する。図６から、０．０５重量％以上の添加量におい
て、多孔質炭素無添加の天然黒鉛負極よりも良好なハイ
レート放電特性が得られたが、０．０５重量％を越える
と改善効果の伸びが鈍化した。(Relationship Between Addition Amount of Porous Carbon and Battery Characteristics) The relationship between the addition amount of porous carbon, high-rate discharge characteristics and cycle characteristics will be described based on the results of FIGS. From FIG. 6, it was found that, at an addition amount of 0.05% by weight or more, a high-rate discharge characteristic better than that of the natural graphite negative electrode without the addition of porous carbon was obtained. Slowed down.
【００６０】他方、図７から、０．０１重量％以上、
２．０重量％以下の添加量範囲において、多孔質炭素無
添加の天然黒鉛負極よりも良好なサイクル特性が得られ
た。また、サイクル特性は、０．１〜１．０重量％の範
囲の添加量で極大となり、１．０重量％を越えて添加量
を増やした場合、逆にサイクル特性が低下した。On the other hand, from FIG.
In the addition amount range of 2.0% by weight or less, better cycle characteristics were obtained than the natural graphite negative electrode to which no porous carbon was added. In addition, the cycle characteristics were maximized at an addition amount in the range of 0.1 to 1.0% by weight, and when the addition amount was increased beyond 1.0% by weight, the cycle characteristics deteriorated conversely.
【００６１】以上の結果から、多孔質炭素の比表面積と
しては、３０ｍ2 / ｇ以上とし、好ましくは１３０ｍ2
/ ｇ、より好ましくは６００ｍ2 / ｇとする。また、多
孔質炭素の平均粒径としては、２０μｍ以下、より好ま
しくは１０μｍ以下とする。更に、多孔質炭素の添加量
としては、好ましくは０．０１重量％ないし２重量％と
し、より好ましくは０．０５重量％ないし１．０重量％
とする。From the above results, the specific surface area of the porous carbon, and 30 m 2 / g or more, preferably 130m 2
/ g, more preferably 600 m 2 / g. The average particle size of the porous carbon is 20 μm or less, more preferably 10 μm or less. Further, the addition amount of the porous carbon is preferably 0.01% by weight to 2% by weight, more preferably 0.05% by weight to 1.0% by weight.
And
【００６２】[0062]
【発明の効果】前述の如く、天然黒鉛はリチウムイオン
が挿入脱離するのに好都合な層間構造を有するが、その
一方で自己滑沢性や劈開性が強く、また電解液保持力が
小さいという負の特性をも有している。この負の特性が
ハイレート放電特性やサイクル特性を低下させる原因と
なっている。よって、従来の天然黒鉛負極では、天然黒
鉛の持つ優れたイオン挿入脱離性を十分に活用できてい
なかった。As described above, natural graphite has an interlayer structure that is convenient for lithium ions to be inserted and desorbed, but on the other hand, has a strong self-lubricating property and a high cleavage property, and has a low electrolyte retention power. It also has negative properties. This negative characteristic causes high-rate discharge characteristics and cycle characteristics to deteriorate. Therefore, in the conventional natural graphite negative electrode, the excellent ion insertion / desorption property of natural graphite could not be fully utilized.
【００６３】本発明によると、多孔質炭素粉末が、天然
黒鉛の上記負の特性に起因する不都合を解消する。よっ
て、本発明によると、天然黒鉛の持つ活物質としての優
れた能力を十分に引き出し得たリチウムイオン二次電池
用負極とでき、この負極を用いることにより、高電圧・
高エネルギー密度でハイレート放電特性およびサイクル
特性にも優れたリチウムイオン電池を提供できる。According to the present invention, the porous carbon powder eliminates the disadvantages caused by the above-mentioned negative properties of natural graphite. Therefore, according to the present invention, it is possible to obtain a negative electrode for a lithium ion secondary battery that can sufficiently draw out the excellent ability of natural graphite as an active material.
A lithium ion battery having high energy density and excellent high-rate discharge characteristics and cycle characteristics can be provided.
【図１】多孔質炭素の比表面積と負極剥離強度との関係
を示すグラフである。FIG. 1 is a graph showing the relationship between the specific surface area of porous carbon and the negative electrode peel strength.
【図２】多孔質炭素の平均粒径と負極剥離強度との関係
を示すグラフである。FIG. 2 is a graph showing the relationship between the average particle size of porous carbon and the negative electrode peel strength.
【図３】多孔質炭素の比表面積とハイレート放電特性と
の関係を示すグラフである。FIG. 3 is a graph showing the relationship between the specific surface area of porous carbon and high-rate discharge characteristics.
【図４】多孔質炭素の比表面積とサイクル特性との関係
を示すグラフである。FIG. 4 is a graph showing the relationship between the specific surface area of porous carbon and cycle characteristics.
【図５】多孔質炭素の添加量と負極剥離強度との関係を
示すグラフである。FIG. 5 is a graph showing the relationship between the amount of porous carbon added and the negative electrode peel strength.
【図６】多孔質炭素の添加量とハイレート放電特性との
関係を示すグラフである。FIG. 6 is a graph showing the relationship between the amount of porous carbon added and high-rate discharge characteristics.
【図７】多孔質炭素の添加量とサイクル特性との関係を
示すグラフである。FIG. 7 is a graph showing the relationship between the amount of porous carbon added and cycle characteristics.
【図８】本発明の実施の形態を説明するためのリチウム
イオン二次電池の断面模式図である。FIG. 8 is a schematic cross-sectional view of a lithium ion secondary battery for describing an embodiment of the present invention.
Claims (7)
としての多孔質炭素粉末と、結着剤とを含み構成された
リチウムイオン二次電池用負極。1. A negative electrode for a lithium ion secondary battery comprising natural graphite as a negative electrode active material, porous carbon powder as an additive, and a binder.
ｍ2 ／ｇ以上であることを特徴とする請求項１記載のリ
チウムイオン二次電池用負極。2. The specific surface area of the porous carbon powder is 30.
Claim 1 negative electrode for a lithium ion secondary battery, wherein a is m 2 / g or more.
０ｍ2 ／ｇ以上であることを特徴とする請求項１記載の
リチウムイオン二次電池用負極。3. The porous carbon powder has a specific surface area of 13
Claim 1 negative electrode for a lithium ion secondary battery, wherein a is 0 m 2 / g or more.
μｍ以下であることを特徴とする請求項１乃至３記載の
リチウムイオン二次電池用負極。4. The porous carbon powder having an average particle size of 20
4. The negative electrode for a lithium ion secondary battery according to claim 1, wherein the thickness is not more than μm.
μｍ以下であることを特徴とする請求項１乃至３記載の
リチウムイオン二次電池用負極。5. The porous carbon powder having an average particle size of 10
4. The negative electrode for a lithium ion secondary battery according to claim 1, wherein the thickness is not more than μm.
対し０．０１重量％ないし２重量％添加されていること
を特徴とする請求項１乃至５記載のリチウムイオン二次
電池用負極。6. The negative electrode for a lithium ion secondary battery according to claim 1, wherein the porous carbon powder is added in an amount of 0.01% by weight to 2% by weight based on the natural graphite.
対し０．０５重量％ないし１．０重量％添加されている
ことを特徴とする請求項１乃至５記載のリチウムイオン
二次電池用負極。7. The lithium ion secondary battery according to claim 1, wherein the porous carbon powder is added in an amount of 0.05% by weight to 1.0% by weight based on the natural graphite. Negative electrode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9079394A JPH10275615A (en) | 1997-03-31 | 1997-03-31 | Negative electrode for lithium ion secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9079394A JPH10275615A (en) | 1997-03-31 | 1997-03-31 | Negative electrode for lithium ion secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10275615A true JPH10275615A (en) | 1998-10-13 |
Family
ID=13688651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9079394A Pending JPH10275615A (en) | 1997-03-31 | 1997-03-31 | Negative electrode for lithium ion secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10275615A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100481229B1 (en) * | 2002-07-04 | 2005-04-07 | 마이크로파우더 주식회사 | Method of fabricating electrode of Lithium secondary battery and Lithium secondary battery with the electrode |
| JP2007095457A (en) * | 2005-09-28 | 2007-04-12 | Hitachi Vehicle Energy Ltd | Nonaqueous electrolytic solution, and lithium secondary battery using its nonaqueous electrolytic solution |
| US7361431B2 (en) * | 2001-12-19 | 2008-04-22 | Samsung Sdi Co., Ltd. | Cathode electrode including a porous conductive material coated and/or filled with sulfur and/or a sulfur-containing organic compound and lithium battery containing the same |
| CN113497222A (en) * | 2020-04-01 | 2021-10-12 | 深圳格林德能源集团有限公司 | Lithium ion battery anode slurry and anode piece |
| CN114551797A (en) * | 2021-07-08 | 2022-05-27 | 万向一二三股份公司 | High-surface-density silicon-carbon negative pole piece |
| WO2022119217A1 (en) * | 2020-12-04 | 2022-06-09 | 주식회사 엘지에너지솔루션 | Electrode for secondadry battery, secondary battery comprising same, and electrode manufacturing method |
| CN114628648A (en) * | 2021-07-08 | 2022-06-14 | 万向一二三股份公司 | High-performance silicon-carbon negative electrode piece and preparation method thereof |
-
1997
- 1997-03-31 JP JP9079394A patent/JPH10275615A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7361431B2 (en) * | 2001-12-19 | 2008-04-22 | Samsung Sdi Co., Ltd. | Cathode electrode including a porous conductive material coated and/or filled with sulfur and/or a sulfur-containing organic compound and lithium battery containing the same |
| KR100481229B1 (en) * | 2002-07-04 | 2005-04-07 | 마이크로파우더 주식회사 | Method of fabricating electrode of Lithium secondary battery and Lithium secondary battery with the electrode |
| JP2007095457A (en) * | 2005-09-28 | 2007-04-12 | Hitachi Vehicle Energy Ltd | Nonaqueous electrolytic solution, and lithium secondary battery using its nonaqueous electrolytic solution |
| CN113497222A (en) * | 2020-04-01 | 2021-10-12 | 深圳格林德能源集团有限公司 | Lithium ion battery anode slurry and anode piece |
| WO2022119217A1 (en) * | 2020-12-04 | 2022-06-09 | 주식회사 엘지에너지솔루션 | Electrode for secondadry battery, secondary battery comprising same, and electrode manufacturing method |
| CN114551797A (en) * | 2021-07-08 | 2022-05-27 | 万向一二三股份公司 | High-surface-density silicon-carbon negative pole piece |
| CN114628648A (en) * | 2021-07-08 | 2022-06-14 | 万向一二三股份公司 | High-performance silicon-carbon negative electrode piece and preparation method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101966774B1 (en) | Negative electrode for secondary battery, preparation method thereof and secondary battery comprising the same | |
| JP5219387B2 (en) | Nonaqueous electrolyte secondary battery | |
| KR101325555B1 (en) | Lithium Secondary Battery Comprising Spherical Graphite as Anode Active Material | |
| JP2006339093A (en) | Wound type nonaqueous electrolyte secondary battery and its negative electrode | |
| JP2007179864A (en) | Negative electrode for nonaqueous secondary battery, its manufacturing method, and nonaqueous secondary battery | |
| JP2011192539A (en) | Electrode for nonaqueous electrolyte secondary battery and method for manufacturing the same, and nonaqueous electrolyte secondary battery | |
| JP7378605B2 (en) | Negative active materials, electrochemical devices and electronic devices | |
| JP3867030B2 (en) | Negative electrode for lithium secondary battery, positive electrode and lithium secondary battery | |
| US20230231100A1 (en) | Electrochemical devices, electronic devices | |
| KR20190047195A (en) | Negative electrode active material for lithium secondary battery and lithium secondary battery comprising the same | |
| CN112005418A (en) | Electrolyte and electrochemical device | |
| KR102335314B1 (en) | Negative electrode for lithium secondary battery, and lithium secondary battery comprising the same | |
| WO2022089280A1 (en) | Electrochemical device and electronic device comprising same | |
| CN115579505A (en) | Secondary battery and power consumption device | |
| JPH1173943A (en) | Nonaqueous electrolyte secondary battery | |
| KR20150016018A (en) | Composite electrode comprising different electrode active material and electrode assembly | |
| JPH10275615A (en) | Negative electrode for lithium ion secondary battery | |
| WO2024055730A1 (en) | Positive electrode sheet, battery cell and battery | |
| JPH11111300A (en) | Negative electrode for nonaqueous secondary battery | |
| JP2005025991A (en) | Nonaqueous electrolyte secondary battery | |
| KR20170135425A (en) | Electrode for lithium secondary battery and lithium secondary battery comprising the same | |
| CN116454545A (en) | Secondary battery and electric equipment | |
| JP3582823B2 (en) | Positive electrode for non-aqueous secondary battery and non-aqueous secondary battery | |
| JPH09289022A (en) | Nonaqueous electrolyte secondary battery | |
| JP6874860B2 (en) | Electrodes containing silicone balls and lithium-ion batteries containing them |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071020 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 8 Free format text: PAYMENT UNTIL: 20081020 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 9 Free format text: PAYMENT UNTIL: 20091020 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091020 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 10 Free format text: PAYMENT UNTIL: 20101020 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101020 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 11 Free format text: PAYMENT UNTIL: 20111020 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111020 Year of fee payment: 11 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121020 Year of fee payment: 12 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131020 Year of fee payment: 13 |
|
| LAPS | Cancellation because of no payment of annual fees |