JP2004281414A - Electrode material for battery, and secondary battery - Google Patents

Electrode material for battery, and secondary battery Download PDF

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JP2004281414A
JP2004281414A JP2004149461A JP2004149461A JP2004281414A JP 2004281414 A JP2004281414 A JP 2004281414A JP 2004149461 A JP2004149461 A JP 2004149461A JP 2004149461 A JP2004149461 A JP 2004149461A JP 2004281414 A JP2004281414 A JP 2004281414A
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battery
electrode
electrode material
active material
powder
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Kunio Nishimura
邦夫 西村
Akitaka Sudo
彰孝 須藤
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Resonac Holdings Corp
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Showa Denko KK
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    • YGENERAL 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
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    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the swelling of an electrode activator like graphite powder and lowering of battery capacity of a secondary battery due to the repetition of charge and discharge. <P>SOLUTION: The electrode material is manufactured by mixing aggregates formed by intertwining dendritic vapor growth carbon fiber and electrode activator powder, and forming a complex body in a state that a part of the electrode activator powder is captured in a fine cavity of the aggregates. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この発明は、二次電池、特にリチウム二次電池、鉛二次電池などに好適な炭素繊維、特に気相成長炭素繊維(VGCF)を使用した電池用電極材(以下、電極材と略記することがある。)に関する。   The present invention relates to an electrode material for a battery using carbon fibers suitable for a secondary battery, particularly a lithium secondary battery, a lead secondary battery, and the like, in particular, a vapor growth carbon fiber (VGCF) (hereinafter abbreviated as an electrode material). There is.)

従来、この種の気相成長炭素繊維を用いた電極材として、特開平4−155776号公報に開示されたものがある。この先行発明の電極材は、コークスを高温熱処理して得られた黒鉛粉末と気相成長炭素繊維を混合したものであり、これをリチウムイオン二次電池の負極として使用するものである。   Conventionally, as an electrode material using this kind of vapor grown carbon fiber, there is one disclosed in Japanese Patent Application Laid-Open No. 4-155776. The electrode material of the prior invention is obtained by mixing graphite powder obtained by subjecting coke to high-temperature heat treatment and vapor-grown carbon fiber, and is used as a negative electrode of a lithium ion secondary battery.

また、特開平4−237971号公報に記載の電極材は、メソカーボンマイクロビースと気相成長炭素繊維を混合したもので、これをやはりリチウムイオン二次電池の負極として使用するものである。
これらの先行発明にあっては、二次電池の充放電を繰り返すことによって生じる電極活物質である黒鉛粉末等の膨張を防止でき、電極材の変形、破損を抑えることができ、これによって容量低下を防ぐことができるとされている。
The electrode material described in JP-A-4-237971 is a mixture of mesocarbon microbeads and vapor-grown carbon fiber, which is also used as a negative electrode of a lithium ion secondary battery.
In these prior arts, it is possible to prevent the expansion of the graphite powder, which is an electrode active material, which is caused by repeating charge and discharge of the secondary battery, and to suppress deformation and breakage of the electrode material, thereby reducing the capacity. It is said that can be prevented.

しかしながら、これらの従来の電極材にあっては、黒鉛粉末等と気相成長炭素繊維とが単に混合された状態にあるだけであるため、黒鉛粉末等の膨潤を気相成長炭素繊維で十分抑えることができず、容量低下を防止する効果は十分とは言えない不都合がある。
特開平4−155776号公報 特開平4−237971号公報
However, in these conventional electrode materials, the swelling of the graphite powder or the like is sufficiently suppressed by the vapor-grown carbon fiber because the graphite powder or the like and the vapor-grown carbon fiber are merely in a mixed state. Therefore, there is a disadvantage that the effect of preventing a decrease in capacity is not sufficient.
JP-A-4-155776 JP-A-4-237971

よって、本発明における課題は、充放電の繰り返しによる黒鉛粉末等の電極活物質の膨張、変形等をより完全に抑えることができ、電池容量の低下を高度に防止することができる電池用電極材を得ることにある。   Therefore, an object of the present invention is to provide a battery electrode material that can more completely suppress expansion, deformation, and the like of an electrode active material such as graphite powder due to repeated charge and discharge, and can highly prevent a reduction in battery capacity. Is to get

かかる課題を解決するため、
請求項1にかかる発明は、気相成長炭素繊維が絡み合って形成され、その繊維相互の接点の一部が固着され、大きさ5〜500μmの凝集体の微細空洞内に電極活物質粉末が包含された複合体からなる電池用電極材である。
請求項2にかかる発明は、電極活物質がリチウム含有複合酸化物である請求項1記載の電池用電極材である。
To solve this problem,
According to the first aspect of the present invention, the vapor-grown carbon fibers are entangled, a part of the contact points between the fibers is fixed, and the electrode active material powder is contained in the fine cavities of the aggregate having a size of 5 to 500 μm. An electrode material for a battery comprising the composite thus obtained.
The invention according to claim 2 is the battery electrode material according to claim 1, wherein the electrode active material is a lithium-containing composite oxide.

請求項3にかかる発明は、電極活物質が黒鉛である請求項1記載の電池用電極材である。
請求項4にかかる発明は、電極活物質が二酸化鉛または金属鉛である請求項1記載の電池用電極材である。
請求項5にかかる発明は、上記凝集体が気相成長樹枝状炭素繊維を圧縮し、加熱し、さらに解砕したものである請求項1記載の電池用電極材である。
請求項6にかかる発明は、上記複合体には同時に炭素粉末が包含されている請求項1記載の電池用電極材である。
The invention according to claim 3 is the battery electrode material according to claim 1, wherein the electrode active material is graphite.
The invention according to claim 4 is the battery electrode material according to claim 1, wherein the electrode active material is lead dioxide or metallic lead.
The invention according to claim 5 is the battery electrode material according to claim 1, wherein the aggregate is obtained by compressing, heating, and further crushing the vapor-grown dendritic carbon fiber.
The invention according to claim 6 is the electrode material for a battery according to claim 1, wherein the composite simultaneously contains carbon powder.

請求項7にかかる発明は、請求項1ないし6のいずれかに記載の電池用電極材を用いてなる二次電池である。
請求項8にかかる発明は、請求項1、2、3、5、および6のいずれかに記載の電池用電極材を用いてなるリチウム二次電池である。
請求項9にかかる発明は、請求項1ないし6のいずれかに記載の電池用電極材と結着剤を含む電極ペーストである。
請求項10にかかる発明は、請求項9記載の電極ペーストの成形体からなる電極である。
The invention according to claim 7 is a secondary battery using the battery electrode material according to any one of claims 1 to 6.
The invention according to claim 8 is a lithium secondary battery using the battery electrode material according to any one of claims 1, 2, 3, 5, and 6.
According to a ninth aspect of the present invention, there is provided an electrode paste comprising the battery electrode material according to any one of the first to sixth aspects and a binder.
According to a tenth aspect of the present invention, there is provided an electrode comprising a molded product of the electrode paste according to the ninth aspect.

本発明によれば、電極活物質が凝集体の微細空洞内に取り込まれるために、電極活物質の充放電による膨張が制限され、電極体自体の変形、破壊が防止できる。また、凝集体は、炭素繊維相互の接触が単なる機械的接触ではなく、炭素繊維が部分的に化学的に結合して繊維が絡みあっているので、凝集体の電気抵抗が低く、得られる電極材の内部抵抗も低くなる。
このため、本発明の電極材にあっては、電極活物質の粒子が凝集体の微細空洞内に取り込まれたり、粒子が炭素繊維に絡み付いたりして、粒子と炭素繊維との接触確率が増加して粒子と炭素繊維との電気的接触が多くなり、かつ凝集体自体の電気抵抗も低いので、内部抵抗が小さく、活物質の無駄がなく、有効に電解反応に関与するので、電池容量が増大する。
また、黒鉛粉末を活物質とした場合には、黒鉛粒子の充放電に起因する膨張が抑えられ、電極材の膨張、変形が防止されて充放電可能な回数が増し、長寿命となる。
According to the present invention, since the electrode active material is taken into the fine cavities of the aggregate, expansion due to charging and discharging of the electrode active material is limited, and deformation and destruction of the electrode body itself can be prevented. In addition, since the aggregates are not mere mechanical contacts, the carbon fibers are partially chemically bonded to each other, and the fibers are entangled. The internal resistance of the material also decreases.
For this reason, in the electrode material of the present invention, the particles of the electrode active material are taken into the fine cavities of the aggregate, or the particles are entangled with the carbon fibers, and the contact probability between the particles and the carbon fibers increases. As the electrical contact between the particles and the carbon fiber increases, and the electrical resistance of the aggregate itself is low, the internal resistance is low, the active material is not wasted, and it effectively participates in the electrolytic reaction. Increase.
When graphite powder is used as the active material, expansion due to charging and discharging of the graphite particles is suppressed, expansion and deformation of the electrode material are prevented, and the number of times that charging and discharging can be performed increases, resulting in a longer life.

以下、本発明を詳しく説明する。
本発明で使用される凝集体は、繊維径が0.01〜5μmの気相法炭素繊維が凝集し、その繊維相互の接点の一部がタール、ピッチなどの炭素物質の炭化物によって化学的に結合して固着された大きさが5〜500μmのフロック状または糸鞠状の構造体であり、その内部には種々の大きさの微細空洞が形成されているものである。
このような凝集体は、繊維径0.05〜5μmの気相成長炭素繊維を圧縮成形し、嵩密度0.02g/cm以上の成形体とし、これを600℃、好ましくは800℃以上で加熱し、さらに機械的に解砕する方法や、該気相成長炭素繊維を0.1kg/cm以上で圧縮しながら600℃以上好ましくは800℃以上で加熱し、さらに解砕する方法などによって製造できる(特願平7−308406号、平成7年11月1日出願、参照)。
Hereinafter, the present invention will be described in detail.
In the aggregate used in the present invention, vapor-grown carbon fiber having a fiber diameter of 0.01 to 5 μm is agglomerated, and a part of the contact point between the fibers is chemically formed by carbonization of a carbon substance such as tar and pitch. It is a floc-like or thread-ball-like structure having a size of 5 to 500 µm which is bonded and fixed, and has fine cavities of various sizes formed therein.
Such an agglomerate is compression molded from vapor-grown carbon fiber having a fiber diameter of 0.05 to 5 μm to form a molded body having a bulk density of 0.02 g / cm 3 or more. A method of heating and further mechanically pulverizing, or a method of heating the vapor grown carbon fiber at 600 ° C. or more, preferably 800 ° C. or more while compressing it at 0.1 kg / cm 2 or more, and further pulverizing. It can be manufactured (see Japanese Patent Application No. 7-308406, filed on November 1, 1995).

また、上記凝集体に使われる気相成長炭素繊維としては、特に限定されず、分岐を有しない単繊維でも、また分岐を有する繊維でもよく、これらを混合したものでもよい。また、生成したままの熱処理されていない粗製の繊維が好ましい。粗製の炭素繊維には、約5〜20重量%のタール、ピッチ等が吸着されており、これが圧縮成形時の繊維間を結合するバインダーとして機能し、さらに熱処理すると容易に炭化して繊維同士を接着する炭化物となる。
もし、熱処理後の気相成長炭素繊維を使用するのであれば、ピッチ等を添加して成形することが望ましい。
The vapor-grown carbon fiber used in the aggregate is not particularly limited, and may be a single fiber having no branch, a fiber having a branch, or a mixture thereof. Further, a crude fiber that has not been heat-treated as produced is preferable. Approximately 5 to 20% by weight of tar, pitch and the like are adsorbed on the crude carbon fiber, which functions as a binder for binding the fibers during compression molding. It becomes carbide to adhere.
If the vapor-grown carbon fiber after the heat treatment is used, it is preferable to add pitch and the like to form.

また、本発明で用いられる電極活物質としては、本発明の電極材をリチウムイオン二次電池の負極とする場合には、黒鉛粉末が用いられる。ここでの黒鉛粉末としては、リチウムイオンをインターカレーションできる層状結晶構造を有するものが用いられ、002面の面間隔(d002)が0.34mm以下のものが好ましい。黒鉛粉末の粒径は平均粒径1〜30μm、好ましくは2〜10μmである。   When the electrode material of the present invention is used as a negative electrode of a lithium ion secondary battery, graphite powder is used as the electrode active material used in the present invention. As the graphite powder, one having a layered crystal structure capable of intercalating lithium ions is used, and one having a 002 plane spacing (d002) of 0.34 mm or less is preferable. The average particle size of the graphite powder is 1 to 30 μm, preferably 2 to 10 μm.

上記凝集体と黒鉛粉末との混合比は、凝集体が混合物の全量の3〜20重量%となるようにされる。3重量%未満では、凝集体を使用した効果が得られず、20重量%を越えると黒鉛粉末の量が減少し、電池容量が低下する。
黒鉛粉末と凝集体とは、十分に混合することが重要であり、混合後の状態において黒鉛粒子が凝集体の炭素繊維に絡み付いた状態、凝集体の内部の空洞に黒鉛粒子が取り込まれた状態あるいはこれがさらに絡み合った状態となっていることが必要である。
このための混合には、混合物に十分な剪断力を作用させうるヘンシェルミキサーやスパルタンリューザなどが用いられる。
The mixing ratio between the aggregate and the graphite powder is such that the aggregate is 3 to 20% by weight of the total amount of the mixture. If the amount is less than 3% by weight, the effect of using the aggregates cannot be obtained. If the amount exceeds 20% by weight, the amount of graphite powder decreases, and the battery capacity decreases.
It is important that the graphite powder and the agglomerate are sufficiently mixed, and the graphite particles are entangled with the carbon fibers of the agglomerate after mixing, and the graphite particles are entrapped in the cavities inside the agglomerate Alternatively, it is necessary that this is further intertwined.
For the mixing for this purpose, a Henschel mixer or a Spartan Luzer that can exert a sufficient shearing force on the mixture is used.

この例での電極材を用いた合剤の具体的構造としては、凝集体と黒鉛粉末とを混合し、これに必要に応じて導電性付与剤としてのカーボンブラック等を添加し、これに結着剤としてのフッ素樹脂などを加えてよく混合してペースト状となし、このものを集電体となる銅箔、ステンレス鋼ネットなどの金属材に塗布、乾燥したシート状のものや集電体となる金属材上に塗布、成形したブロック状のものなどがある。   As a specific structure of the mixture using the electrode material in this example, an aggregate and graphite powder are mixed, and if necessary, carbon black or the like as a conductivity-imparting agent is added thereto. Add a fluororesin as a binder and mix well to form a paste, apply this to a metal material such as a copper foil or stainless steel net as a current collector, and dry it in a sheet or current collector Block-shaped ones applied and formed on a metal material to be used.

この例の電極活物質として黒鉛粉末を用いる電極材では、負極に限らず、正極に用いることもできる。この場合には、負極には金属リチウムが用いられる。   The electrode material using graphite powder as the electrode active material in this example can be used not only for the negative electrode but also for the positive electrode. In this case, metallic lithium is used for the negative electrode.

また、リチウムイオン二次電池の正極とする場合には、電極活物質として、LiCoO、LiMnOあるいはこれらのCo、Mnの一部をCo、Mn、Fe、Ni等で置換したリチウム複合酸化物の粉末が用いられる。
これらのリチウム複合酸化物は、Li、Co、Mn、Fe、Niなどの炭酸塩や酸化物を混合し、焼成することによって得られ、焼成物を粉砕して粉末とする。
When the positive electrode of a lithium ion secondary battery is used, LiCoO 2 , LiMnO 2, or a lithium composite oxide obtained by substituting a part of these Co and Mn with Co, Mn, Fe, Ni or the like as an electrode active material Powder is used.
These lithium composite oxides are obtained by mixing carbonates and oxides such as Li, Co, Mn, Fe, and Ni and firing the mixture, and pulverize the fired product into powder.

リチウム複合酸化物粉末を活物質とした場合には、導電性付与剤として、カーボンブラック、黒鉛粉末が添加され、これに上記凝集体を加えて混合することにより、電極材となる。
ここでの混合も先の例と同様でリチウム酸化物粉末と凝集体を十分に剪断力を作用させて混合することが必要となる。
凝集体の混合割合は、リチウム複合酸化物と凝集体との混合物全量の5〜20重量%とされ、5重量%未満では凝集体添加効果が発現せず、20重量%を越えると活物質が減少し、電池容量が低下する。
この例での電極材を用いた合剤の具体的な構造は、先の例と同様である。
When a lithium composite oxide powder is used as an active material, carbon black and graphite powder are added as a conductivity-imparting agent, and the above-mentioned aggregate is added thereto and mixed to form an electrode material.
The mixing here is also the same as in the previous example, and it is necessary to mix the lithium oxide powder and the aggregate by applying sufficient shearing force.
The mixing ratio of the aggregates is 5 to 20% by weight of the total amount of the mixture of the lithium composite oxide and the aggregates. If the amount is less than 5% by weight, the effect of adding the aggregates is not exhibited. And the battery capacity decreases.
The specific structure of the mixture using the electrode material in this example is the same as in the previous example.

また、本発明の電極材は、密閉形の鉛二次電池(鉛蓄電池)の電極材として使用できる。
この場合の正極用電極材を用いた合剤の具体的構造は、例えば活物質としての二酸化鉛粉末と上記凝集体とを混合し、これに硫酸水溶液を加えてペースト状とし、このペーストを鉛合金などからなる格子状の集電体に塗布、充填し、乾燥したものなどがある。
Further, the electrode material of the present invention can be used as an electrode material for a sealed lead secondary battery (lead storage battery).
In this case, the specific structure of the mixture using the positive electrode material is, for example, a mixture of lead dioxide powder as an active material and the above-mentioned aggregate, and a sulfuric acid aqueous solution is added thereto to form a paste. A grid-like current collector made of an alloy or the like is applied, filled, and dried.

また、負極用電極材を用いた合剤の具体的構造としては、例えば活物質としての金属鉛粉末と上記凝集体とを混合し、これに硫酸水溶液を添加してペーストとし、このペーストを鉛又は鉛合金からなる格子状の集電体に塗布、充填し、乾燥したものなどが挙げられる。   As a specific structure of the mixture using the electrode material for the negative electrode, for example, a metal lead powder as an active material and the above aggregate are mixed, and an aqueous sulfuric acid solution is added thereto to form a paste. Alternatively, a material obtained by applying, filling, and drying a grid-like current collector made of a lead alloy may be used.

このような構造の電極材にあっては、電極活物質の粒子が凝集体の微細空洞内に取り込まれ、あるいは粒子が凝集体の炭素繊維に絡み付くので、個々の粒子と炭素繊維との接触確率が増加し、電気的接触点が大幅に増大する。このため、電流が極めて流れ易くなり、内部抵抗が低下し、かつ活物質が無駄なく有効に電解反応に関与し、電池容量も増大する。   In the electrode material having such a structure, since the particles of the electrode active material are taken into the fine cavities of the aggregate or the particles are entangled with the carbon fibers of the aggregate, the contact probability between the individual particles and the carbon fibers is increased. And the number of electrical contacts increases significantly. For this reason, the current becomes extremely easy to flow, the internal resistance is reduced, the active material is effectively involved in the electrolytic reaction without waste, and the battery capacity is increased.

さらに、電極活物質が黒鉛粉末の場合には、上記作用効果に加えて、黒鉛粒子の大部分が凝集体内の微細空洞に取り込まれるため、充放電による黒鉛粒子の膨張が抑えられる。このため、電極材自体が膨潤し、変形することがなく、充放電の繰り返しによる電池容量の低下が防止され、長寿命となる。   Further, when the electrode active material is graphite powder, in addition to the above-described effects, most of the graphite particles are taken into the fine voids in the aggregate, so that the expansion of the graphite particles due to charge and discharge is suppressed. For this reason, the electrode material itself does not swell and is not deformed, and a decrease in battery capacity due to repetition of charge and discharge is prevented, resulting in a long life.

本発明の電極材を用いて二次電池を構成するには、リチウムイオン二次電池の場合では、例えば上述した正極用のシート状電極合剤と負極用のシート状電極合剤との間にポリプロピレン不織布などからなるシート状のセパレータを挟み込み、この積層物を渦巻状に巻回する。このもののそれぞれの合剤の集電体にリード線を取り付けて、缶体に収容し、過塩素酸リチウムなどのリチウム塩を溶解したエチレンカーボネート、プロピレンカーボネートなどの電解液を注入するなどの方法で行われる。
勿論、これ以外の種々の形態を取りうることは説明するまでもない。
To configure a secondary battery using the electrode material of the present invention, in the case of a lithium ion secondary battery, for example, between the above-mentioned sheet electrode mixture for the positive electrode and the sheet electrode mixture for the negative electrode A sheet-like separator made of polypropylene nonwoven fabric or the like is sandwiched, and the laminate is spirally wound. Attach a lead wire to the current collector of each mixture of this thing, house it in a can, and inject an electrolyte such as ethylene carbonate or propylene carbonate in which a lithium salt such as lithium perchlorate is dissolved. Done.
Of course, it is needless to say that various other forms can be taken.

以下、具体例を示す。
(実施例1)
本実施例では、図1に示す構造のコイン型リチウムイオン電池を作成した。図中符号1は電池ケース、2は封口板であり、これらは、耐電解液性のステンレス鋼板からなるものである。電池ケース1内には、ステンレス鋼ネットからなる正極集電体3がスポット溶接によって取り付けられている。この正極集電体3には正極電極材4が設けられて、正極となっている。
この正極電極材4は、黒鉛粉末95重量部と上記凝集体5重量部とを混合し、この混合物8重量部に対してフッ素樹脂結着剤2重量部を加え、ヘンシェルミキサーによって混合した合剤0.2gを正極集電体3上に充填、成形したものである。
Hereinafter, specific examples will be described.
(Example 1)
In this example, a coin-type lithium ion battery having the structure shown in FIG. 1 was produced. In the figure, reference numeral 1 denotes a battery case, 2 denotes a sealing plate, and these are made of an electrolytic solution-resistant stainless steel plate. A positive electrode current collector 3 made of a stainless steel net is mounted in the battery case 1 by spot welding. The positive electrode current collector 3 is provided with a positive electrode material 4 to serve as a positive electrode.
The positive electrode material 4 was obtained by mixing 95 parts by weight of graphite powder and 5 parts by weight of the above-mentioned aggregate, adding 2 parts by weight of a fluororesin binder to 8 parts by weight of the mixture, and mixing the mixture with a Henschel mixer. 0.2 g was filled and molded on the positive electrode current collector 3.

上記黒鉛粉末には、温度3000℃で加熱処理した人造黒鉛電極(d002=0.338nm)を粉砕して平均粒径5μmとしたものを用いた。
上記凝集体には、分枝状の気相成長炭素繊維を圧縮成形し、嵩密度0.06g/cmとした成形体を1300℃で熱処理し、さらに2800℃で5分間加熱し黒鉛化したものを解砕して大きさが100〜300μmのフロック状のもの(d002=0.339nm)を用いた。
As the graphite powder, an artificial graphite electrode (d002 = 0.338 nm) heat-treated at a temperature of 3000 ° C. was pulverized to have an average particle size of 5 μm.
The above-mentioned aggregate was subjected to compression-molding of a branched vapor-grown carbon fiber, heat-treating a compact having a bulk density of 0.06 g / cm 2 at 1300 ° C., and further heating at 2800 ° C. for 5 minutes to graphitize. The material was crushed and used as a floc having a size of 100 to 300 μm (d002 = 0.339 nm).

正極電極体4上には微孔性のポリプロピレン製セパレータ5が設けられ、このセパレータ5上には円板状の金属リチウムの負極6が設けられ、この負極6は封口板2に接合されている。符号7は、ポリプロピレン製のパッキングである。
電解液には、エチレンカーボネートとジエチルカーボネートとの等容積混合溶媒にLiPFを1モル/リットルの濃度となるように溶解した溶液を用いた。
このコイン型電池の寸法は、直径20mm、厚さ16mmであった。
A microporous polypropylene separator 5 is provided on the positive electrode 4, and a disc-shaped negative electrode 6 of metallic lithium is provided on the separator 5, and the negative electrode 6 is joined to the sealing plate 2. . Reference numeral 7 is a packing made of polypropylene.
As the electrolytic solution, a solution obtained by dissolving LiPF 6 at a concentration of 1 mol / L in a mixed solvent of equal volumes of ethylene carbonate and diethyl carbonate was used.
The dimensions of the coin-type battery were 20 mm in diameter and 16 mm in thickness.

(比較例1)
実施例1において、人造黒鉛電極粉砕粉末8重量部に対してフッ素樹脂結着剤2重量部を加え、ヘンシェルミキサーで混合した合剤0.2gを正極集電体3上に充填、成形した以外は同様にしてコイン型電池を作成した。
(Comparative Example 1)
In Example 1, except that 2 parts by weight of a fluororesin binder was added to 8 parts by weight of the pulverized artificial graphite electrode powder, and 0.2 g of a mixture mixed with a Henschel mixer was filled on the positive electrode current collector 3 and molded. Produced a coin-type battery in the same manner.

(比較例2)
実施例1において、人造黒鉛電極粉砕粉末95重量部と、特公昭62−49363号公報に示された方法で合成された平均繊維径0.2μm、平均繊維長さ30μmの気相成長炭素繊維をアルゴン中で2800℃で5分間加熱して部分的に黒鉛化した炭素繊維5重量部とを混合し、この混合物8重量部に対してフッ素樹脂結着剤2重量部を加え、ヘンシェルミキサーで混合した合剤0.2gを正極集電体3上に充填、成形した以外は同様にしてコイン型電池を作成した。
(Comparative Example 2)
In Example 1, 95 parts by weight of the pulverized artificial graphite electrode powder and a vapor-grown carbon fiber having an average fiber diameter of 0.2 μm and an average fiber length of 30 μm synthesized by the method disclosed in JP-B-62-49363 were used. Heating at 2800 ° C. for 5 minutes in argon, 5 parts by weight of partially graphitized carbon fibers were mixed, and 8 parts by weight of this mixture was added with 2 parts by weight of a fluororesin binder, and mixed with a Henschel mixer. A coin-type battery was prepared in the same manner except that 0.2 g of the mixture thus prepared was filled and molded on the positive electrode current collector 3.

これら3種のコイン型電池について、100mHz時の内部抵抗値、正極黒鉛粉末の重量エネルギー密度、充放電回数を測定した。
充放電条件は、電流密度0.3mA/cm、充電終止電圧3.0V、放電終止電圧0Vで、定電流充放電を行った。
結果を表1、表2、表3に示す。
The internal resistance at 100 mHz, the weight energy density of the positive graphite powder, and the number of times of charging and discharging were measured for these three types of coin batteries.
The charge and discharge conditions were a constant current charge and discharge at a current density of 0.3 mA / cm 2 , a charge end voltage of 3.0 V, and a discharge end voltage of 0 V.
The results are shown in Tables 1, 2 and 3.

Figure 2004281414
Figure 2004281414

Figure 2004281414
Figure 2004281414

Figure 2004281414
Figure 2004281414

(実施例2)
実施例1で使用した正極を負極とし、集電体のステンレス鋼ネットを封口板にスポット溶接した。
正極として、LiCoO 80重量部と実施例1での凝集体10重量部とフッ素樹脂結着剤100重量部とをヘンシェルミキサーで混合した合剤0.4gをチタン製ネットの正極集電体とともにケース内に充填、成形したものを用いた以外は実施例1と同様にしてボタン電池を作成した。
(Example 2)
The positive electrode used in Example 1 was used as a negative electrode, and a stainless steel net as a current collector was spot-welded to a sealing plate.
As the positive electrode, 0.4 g of a mixture obtained by mixing 80 parts by weight of LiCoO 2 , 10 parts by weight of the aggregate in Example 1, and 100 parts by weight of the fluororesin binder with a Henschel mixer together with a positive electrode current collector of a titanium net A button battery was prepared in the same manner as in Example 1 except that a battery filled and molded in a case was used.

このボタン電池について、充放電電流密度2.0mA/cm、充電終止電圧4.0V、放電終止電圧2.7Vの条件下で定電流充放電試験を行った。
その結果、重量エネルギー密度は140mAh/gであり、500サイクルの充放電後において初期エネルギー密度の94%を維持していた。
This button battery was subjected to a constant current charge / discharge test under the conditions of a charge / discharge current density of 2.0 mA / cm 2 , a charge end voltage of 4.0 V, and a discharge end voltage of 2.7 V.
As a result, the weight energy density was 140 mAh / g, and maintained 94% of the initial energy density after 500 cycles of charge and discharge.

(比較例3)
実施例2において、正極として、LiCoO 8重量部とアセチレンブラック1重量部とフッ素樹脂結着剤1重量部とをヘンシェルミキサーで混合した合剤0.4gを用いた以外は同様にして、ボタン電池を作成した。
このものについて、実施例2と同様の試験条件で充放電試験を行ったところ、重量エネルギー密度は120mAh/gであり、500サイクルの充放電後において初期エネルギー密度の70%を維持していた。
(Comparative Example 3)
A button was prepared in the same manner as in Example 2 except that as a positive electrode, 0.4 g of a mixture obtained by mixing 8 parts by weight of LiCoO 2, 1 part by weight of acetylene black, and 1 part by weight of a fluororesin binder with a Henschel mixer was used. Battery was created.
This was subjected to a charge / discharge test under the same test conditions as in Example 2. As a result, the weight energy density was 120 mAh / g, and 70% of the initial energy density was maintained after 500 cycles of charge / discharge.

(比較例4)
実施例2において、正極としてLiCoO 8重量部と、比較例2で使用した気相炭素繊維1重量部とフッ素樹脂結着剤1重量部をヘンシェルミキサーで混合した合剤0.4gを用いた以外は同様にしてボタン電池を作成した。
このものについて、実施例2と同様の試験条件で充放電試験を行ったところ、重量エネルギー密度は130mAh/gであり、500サイクルの充放電後において初期エネルギー密度の78%を維持していた。
(Comparative Example 4)
In Example 2, 0.4 g of a mixture obtained by mixing 8 parts by weight of LiCoO 2 as a positive electrode, 1 part by weight of gas-phase carbon fibers used in Comparative Example 2 and 1 part by weight of a fluororesin binder with a Henschel mixer was used. Except for the above, a button battery was prepared in the same manner.
This was subjected to a charge / discharge test under the same test conditions as in Example 2. As a result, the weight energy density was 130 mAh / g, and 78% of the initial energy density was maintained after 500 cycles of charge / discharge.

本発明の実施例におけるボタン電池の例を示す概略断面図である。It is an outline sectional view showing an example of a button battery in an example of the present invention.

Claims (10)

気相成長炭素繊維が絡み合って形成され、その繊維相互の接点の一部が固着され、大きさ5〜500μmの凝集体の微細空洞内に電極活物質粉末が包含された複合体からなる電池用電極材。   A battery comprising a composite in which vapor-grown carbon fibers are entangled, a part of the contact points between the fibers is fixed, and an electrode active material powder is contained in a fine cavity of an aggregate having a size of 5 to 500 μm. Electrode material. 電極活物質がリチウム含有複合酸化物である請求項1記載の電池用電極材。   The battery electrode material according to claim 1, wherein the electrode active material is a lithium-containing composite oxide. 電極活物質が黒鉛である請求項1記載の電池用電極材。   The battery electrode material according to claim 1, wherein the electrode active material is graphite. 電極活物質が二酸化鉛または金属鉛である請求項1記載の電池用電極材。   The battery electrode material according to claim 1, wherein the electrode active material is lead dioxide or metallic lead. 上記凝集体が気相成長樹枝状炭素繊維を圧縮し、加熱し、さらに解砕したものである請求項1記載の電池用電極材。   2. The electrode material for a battery according to claim 1, wherein the aggregate is obtained by compressing, heating and further crushing the vapor-grown dendritic carbon fiber. 上記複合体には同時に炭素粉末が包含されている請求項1記載の電池用電極材。   2. The electrode material for a battery according to claim 1, wherein the composite contains carbon powder at the same time. 請求項1ないし6のいずれかに記載の電池用電極材を用いてなる二次電池。   A secondary battery using the battery electrode material according to claim 1. 請求項1、2、3、5、および6のいずれかに記載の電池用電極材を用いてなるリチウム二次電池。   A lithium secondary battery using the battery electrode material according to any one of claims 1, 2, 3, 5, and 6. 請求項1ないし6のいずれかに記載の電池用電極材と結着剤を含む電極ペースト。   An electrode paste comprising the battery electrode material according to claim 1 and a binder. 請求項9記載の電極ペーストの成形体からなる電極。
An electrode comprising a molded product of the electrode paste according to claim 9.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007145015A1 (en) * 2006-06-16 2007-12-21 Sharp Kabushiki Kaisha Positive electrode, process for producing the same, and lithium secondary battery utilizing the positive electrode

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007145015A1 (en) * 2006-06-16 2007-12-21 Sharp Kabushiki Kaisha Positive electrode, process for producing the same, and lithium secondary battery utilizing the positive electrode

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