JP3262566B2 - Negative electrode for non-aqueous electrolyte secondary battery - Google Patents
Negative electrode for non-aqueous electrolyte secondary batteryInfo
- Publication number
- JP3262566B2 JP3262566B2 JP19249591A JP19249591A JP3262566B2 JP 3262566 B2 JP3262566 B2 JP 3262566B2 JP 19249591 A JP19249591 A JP 19249591A JP 19249591 A JP19249591 A JP 19249591A JP 3262566 B2 JP3262566 B2 JP 3262566B2
- Authority
- JP
- Japan
- Prior art keywords
- carbon fiber
- aqueous electrolyte
- electrolyte secondary
- negative electrode
- secondary battery
- 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.)
- Expired - Fee Related
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
Description
【０００１】[0001]
【産業上の利用分野】本発明は、非水電解質二次電池用
負極に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode for a non-aqueous electrolyte secondary battery.
【０００２】[0002]
【従来の技術とその課題】非水電解質二次電池は、リチ
ウムやカルシウム等の卑な金属が使用できるために水溶
液系電解液二次電池と比較して高い放電電圧とエネルギ
ー密度が得られる。2. Description of the Related Art A non-aqueous electrolyte secondary battery can obtain a higher discharge voltage and higher energy density than an aqueous electrolyte secondary battery because a base metal such as lithium or calcium can be used.
【０００３】非水電解質二次電池は、有機電解液または
固体電解質を電解液に用いた電池であって、 MnO2 、Li
x Mn2 O4 (0≦x ≦1)、Lix Coy Mn2-y O4 (0≦x ≦1,
0 ≦y ≦1)、 a-V2 O5 、 TiS2 、Lix CoO2 (0≦x ≦
1)などの種々の活物質が正極に用いられている。近年、
従来のリチウムに代わって、負極に炭素材からなるイン
ターカレーション電極を用いたものが注目されている。[0003] non-aqueous electrolyte secondary battery is a battery using the organic electrolytic solution or a solid electrolyte in the electrolytic solution, MnO 2, Li
x Mn 2 O 4 (0 ≦ x ≦ 1), Li x Co y Mn 2-y O 4 (0 ≦ x ≦ 1,
0 ≤ y ≤ 1), aV 2 O 5 , TiS 2 , Li x CoO 2 (0 ≤ x ≤
Various active materials such as 1) are used for the positive electrode. recent years,
Attention has been paid to a negative electrode using an intercalation electrode made of a carbon material instead of lithium.
【０００４】炭素材には、天然黒鉛、人工黒鉛、ＰＡＮ
系炭素繊維、ピッチ系炭素繊維、レーヨン系炭素繊維、
気相成長炭素繊維、特定の高分子化合物の熱分解による
炭素体、熱分解ＣＶＤ法による炭素体、そして活性炭な
どがあり、これらはそれぞれインターカレーション電極
になり得るが、これらのうち実用上、非水電解質二次電
池の負極となり得るものは限られる。[0004] Carbon materials include natural graphite, artificial graphite, and PAN.
-Based carbon fiber, pitch-based carbon fiber, rayon-based carbon fiber,
There are vapor-grown carbon fibers, carbon bodies obtained by pyrolysis of specific polymer compounds, carbon bodies obtained by pyrolysis CVD, activated carbon, and the like. These can be intercalation electrodes. What can be a negative electrode of a nonaqueous electrolyte secondary battery is limited.
【０００５】例えば、天然黒鉛は不純物の混入があるの
で安定した性能を出すことは期待できない。また結晶化
の進んだ人工黒鉛は、Ｘ線回折法による（００２）面の
面間隔ｄ002 が短く、結晶面の広さＬa と厚さＬc が大
きいために、層間の深部へイオンがインターカレートす
ることが難しくなり、放電容量は理論値よりもかなり少
なくなる。[0005] For example, natural graphite cannot be expected to exhibit stable performance because it contains impurities. Further, in the artificial graphite which has been crystallized, ions are intercalated deep into the interlayer due to a short interplanar spacing d 002 of the (002) plane by X-ray diffraction and a large crystal plane width La and thickness Lc. And the discharge capacity is much lower than the theoretical value.
【０００６】ＰＡＮ系、ピッチ系、レーヨン系炭素繊維
で熱処理温度の高いものは高度に黒鉛化され、一部のピ
ッチ系を除いて結晶化の進んだ人工黒鉛と同様に、非水
電解質二次電池の負極としては使用できない。熱処理温
度の低いものは不純物質の残留や出発物質の骨格の影響
が残るために容量は減少し、円滑な充放電が阻害される
ので同様に使用できない。[0006] PAN-based, pitch-based and rayon-based carbon fibers having a high heat treatment temperature are highly graphitized, and except for some pitch-based carbon fibers, like non-aqueous electrolyte secondary graphite, as well as highly crystallized artificial graphite. It cannot be used as a negative electrode for batteries. If the heat treatment temperature is low, the capacity is reduced due to the residual impurities and the influence of the skeleton of the starting material, and smooth charge / discharge is hindered.
【０００７】熱分解による炭素体は多数の報告がされて
いるが、厚みの大きい極板を成型することが難しいので
高容量を持つ電極には向いていなかった。Although there have been many reports of pyrolytic carbon bodies, it has been unsuitable for electrodes having a high capacity because it is difficult to form a thick electrode plate.
【０００８】活性炭は表面上でのイオンの吸着、脱着に
より放電が起こるのでインターカレーション電極ではな
く、キャパシタとして使用され、二次電池用の電極とし
ては適さない。[0008] Activated carbon is used not as an intercalation electrode but as a capacitor, and is not suitable as an electrode for a secondary battery, because discharge occurs due to adsorption and desorption of ions on the surface.
【０００９】これらと比較して、気相成長炭素繊維はそ
の形状と内部構造により優れたインターカレーション電
極材料であるといえる。[0009] In comparison with these, it can be said that the vapor grown carbon fiber is an excellent intercalation electrode material due to its shape and internal structure.
【００１０】本発明でいう気相成長炭素繊維とは金属の
微粒子を触媒として、炭化水素が分解して繊維状に成長
したものであり、必要により不活性気流中で１０００〜
３０００℃で黒鉛化したものである。例えば特公昭６２
−４９３６３号等に記載されているものである。[0010] The vapor-grown carbon fiber referred to in the present invention is a fibrous structure obtained by decomposing hydrocarbons using fine metal particles as a catalyst.
It was graphitized at 3000 ° C. For example, Tokiko Sho 62
-49363 and the like.
【００１１】気相成長炭素繊維は、その結晶が軸方向に
成長しているので、イオンのインターカレーションは繊
維の両端面からおこるものと考えられる。通常、気相成
長炭素繊維は、そのままでは炭素繊維の長さ（Ｌ）と直
径（Ｄ）の比（Ｌ／Ｄ）が大きすぎるため、リチウムイ
オンやその他のイオンの層間深部へのインターカレーシ
ョンが物理的に難しくなる。また、端面が球状にて生成
するので金属イオンのインターカレーションする入口が
閉ざされる。Since the crystal of the vapor grown carbon fiber grows in the axial direction, it is considered that ion intercalation occurs from both end faces of the fiber. Normally, the vapor-grown carbon fiber has an excessively large ratio (L / D) of the length (L) to the diameter (D) of the carbon fiber as it is, so that lithium ions and other ions are intercalated into the deep part of the interlayer. Becomes physically difficult. In addition, since the end face is formed in a spherical shape, the inlet for intercalating metal ions is closed.
【００１２】これらを解決するために炭素繊維を切断す
る方法が考えられた。切断操作によってＬ／Ｄを減じる
ことができ、端面では中心に孔の開いた玉葱の横断面状
の構造が露出する。リチウムイオンやその他の金属イオ
ンは、中心孔や同心円状の結晶層間を移動して繊維中に
拡散でき、炭素繊維全体でインターカレーションが容易
になる効果があると考えられた。しかし、外形の小さい
炭素繊維の切断や特に、端面の切断は容易ではなく、実
際には端面の切断されていないものや炭素繊維の長さ
（Ｌ）の長いものが多数残っていた。このように切断に
よる方法は炭素繊維中へイオンが有効にインターカレー
トするための決定的な方法ではなく、この処理を行った
炭素繊維はインターカレーション電極として有効に使用
されてはいなかった。In order to solve these problems, a method of cutting carbon fibers has been considered. L / D can be reduced by the cutting operation, and a cross-sectional structure of an onion having a hole at the center is exposed at the end face. It is considered that lithium ions and other metal ions can diffuse in the fiber by moving between the central hole and the concentric crystal layer, and have an effect of facilitating intercalation in the entire carbon fiber. However, it is not easy to cut a carbon fiber having a small outer shape, and particularly, to cut an end face. In fact, many uncut end faces and long carbon fiber lengths (L) remain. Thus, the cutting method is not a definitive method for effectively intercalating ions into the carbon fiber, and the carbon fiber subjected to this treatment has not been effectively used as an intercalation electrode.
【００１３】[0013]
【課題を解決するための手段】本発明による非水電解質
二次電池用負極は、直径が０．１〜５．０μｍであり、
長さが０．５〜１０００μｍである気相成長炭素繊維で
あり、かつその気相成長炭素繊維表面に酸化処理を施
し、繊維表面面積の５〜６０％に平均孔径が０．０１〜
２．５μｍである孔を開け、その比表面積が１００ｍ2
／ｇ以下であることを特徴とするものである。A negative electrode for a non-aqueous electrolyte secondary battery according to the present invention has a diameter of 0.1 to 5.0 μm,
A vapor-grown carbon fiber having a length of 0.5 to 1000 μm, and the surface of the vapor-grown carbon fiber is subjected to an oxidation treatment, and the average pore size is 0.01 to 5 to 60% of the fiber surface area.
A hole having a diameter of 2.5 μm is formed and the specific surface area is 100 m 2.
/ G or less.
【００１４】[0014]
【作用】円筒状の気相成長炭素繊維の繊維表面面積の５
〜６０％に平均孔径が０．０１〜０．８μｍである孔を
結晶層の内部へ向かって開くように酸化処理を施すこと
は、両端面の切断されていない炭素繊維の両端面を切断
することと同様の効果を得る。The fiber surface area of the cylindrical vapor grown carbon fiber is 5
Performing the oxidation treatment so as to open pores having an average pore diameter of 0.01 to 0.8 μm to the inside of the crystal layer to ６０60% cuts both end faces of the carbon fiber whose both end faces are not cut. The same effect can be obtained.
【００１５】また、炭素繊維の長さ（Ｌ）の長いものは
孔を開けた部分よりイオンのインターカレートが可能で
あるので、繊維の長さを切断したと同様の効果を得るこ
とができる。In the case of a carbon fiber having a long length (L), ions can be intercalated from a portion where a hole is formed, so that the same effect as when the length of the fiber is cut can be obtained. .
【００１６】従って、酸化処理により気相成長炭素繊維
の側面に孔を開けることは、従来行ってきた切断工程の
不備や不足を補うことができる。Therefore, making holes in the side surfaces of the vapor-grown carbon fibers by the oxidation treatment can make up for the deficiencies and shortages of the cutting step conventionally performed.
【００１７】しかし、酸化処理が強すぎると結晶層が過
度に破壊され電極として用いることができず、また弱す
ぎると酸化処理の効果が認められない。However, if the oxidation treatment is too strong, the crystal layer will be excessively broken and cannot be used as an electrode. If the oxidation treatment is too weak, the effect of the oxidation treatment will not be recognized.
【００１８】このため酸化処理による孔の占める割合は
気相成長炭素繊維の表面積の５〜６０％、好ましくは１
０〜３０％、さらに好ましくは１５〜２０％である。５
％未満の場合は酸化処理の効果が少なく、６０％より多
くなると酸化処理による結晶層の破壊が目立つようにな
るとともに、気相成長炭素繊維の酸化処理による損失分
が多くなるので実用上の使用が難しくなる。For this reason, the proportion of pores occupied by the oxidation treatment is 5 to 60%, preferably 1 to the surface area of the vapor grown carbon fiber.
It is 0 to 30%, more preferably 15 to 20%. 5
%, The effect of the oxidation treatment is small, and if it is more than 60%, the destruction of the crystal layer by the oxidation treatment becomes conspicuous, and the loss due to the oxidation treatment of the vapor-grown carbon fiber increases, so that it is practically used. Becomes difficult.
【００１９】孔の占める割合が表面積の５〜６０％のと
きにできる孔径は繊維径によって異なるが、０．０１〜
２．５μｍの範囲が好ましい。このとき、孔の占める割
合は走査型電子顕微鏡により１万〜５万倍で撮影された
写真より観察された孔をすべて面積測定することにより
行う。The pore diameter formed when the proportion of the pores is 5 to 60% of the surface area varies depending on the fiber diameter.
A range of 2.5 μm is preferred. At this time, the ratio of the holes occupied is determined by measuring the area of all the holes observed from a photograph taken at 10,000 to 50,000 times with a scanning electron microscope.
【００２０】このように酸化処理をした電極のエネルギ
ー密度（放電容量）は、酸化処理をしないものと比較し
て大きく向上する。The energy density (discharge capacity) of the electrode thus oxidized is greatly improved as compared with the electrode not oxidized.
【００２１】本発明でいう酸化処理方法としては、高温
水蒸気処理、高温塩類処理、高温空気酸化処理等が挙げ
られる。Examples of the oxidation treatment method in the present invention include high-temperature steam treatment, high-temperature salt treatment, and high-temperature air oxidation treatment.
【００２２】しかし、塩類を使用した場合は不純物とし
て、例えばZnCl2 等の塩が残り問題があり、また高温空
気酸化処理では酸化崩壊による繊維表面の欠落が多く好
ましくない。However, when salts are used, there is a problem that salts such as ZnCl 2 remain as impurities, and the high temperature air oxidation treatment is not preferable because the fiber surface is often lost due to oxidative collapse.
【００２３】高温水蒸気処理による酸化の場合、不純物
の混入がなく、酸化崩壊が少なく、本発明に最も適して
いる。In the case of oxidation by high-temperature steam treatment, there is no contamination of impurities and there is little oxidative degradation, and it is most suitable for the present invention.
【００２４】高温水蒸気処理は通常、気相成長炭素繊維
を８００〜１２００℃程度の水蒸気雰囲気（水分が１０
〜９０vol ％になる様に窒素等の不活性ガスで希釈され
たものが良い）に１〜３０分間滞在させることにより行
われる。この処理により、気相成長炭素繊維の表面積
（ＢＥＴ法による比表面積）は、処理前の１．５〜５．
０倍程度になる。例えば、処理前の比表面積が１２ｍ2
／ｇであったものが２５ｍ2 ／ｇ、あるいは１５ｍ2 ／
ｇであったものが４７ｍ2 ／ｇに増加した。In the high-temperature steam treatment, the vapor-grown carbon fiber is usually heated in a steam atmosphere of about 800 to 1200 ° C.
で 90 vol%, preferably diluted with an inert gas such as nitrogen) for 1 to 30 minutes. By this treatment, the surface area (specific surface area by the BET method) of the vapor-grown carbon fiber becomes 1.5 to 5.
It becomes about 0 times. For example, the specific surface area before treatment is 12 m 2
/ What had been a g is 25m 2 / g, or 15m 2 /
g increased to 47 m 2 / g.
【００２５】尚、一般に言われる活性炭あるいは活性炭
素繊維は約１０００ｍ2 ／ｇと極めて大きい比表面積で
ある。これらは数〜十数オングストロームの微細な小孔
より成るものである。本発明の酸化処理気相成長炭素繊
維は、結晶表面より結晶子へイオンが出入することを目
的とするので、比表面積は１００ｍ2 ／ｇ以下で十分で
ある。Activated carbon or activated carbon fibers generally referred to have an extremely large specific surface area of about 1000 m 2 / g. These are composed of fine pores of several to several tens angstroms. Since the oxidation-treated vapor-grown carbon fiber of the present invention aims to allow ions to enter and exit the crystallite from the crystal surface, the specific surface area of 100 m 2 / g or less is sufficient.
【００２６】なお、本発明で示すＬ／Ｄは、走査型電子
顕微鏡観察により、ランダムに選ばれた１００本以上の
繊維のＬ／Ｄ値の平均値とした。The L / D shown in the present invention was an average value of L / D values of 100 or more fibers selected at random by observation with a scanning electron microscope.
【００２７】本発明で用いられる気相成長炭素繊維には
Ｘ線回折法による（００２）面の結晶層間距離ｄ002 が
３．３５〜３．７０オングストローム、同じく結晶層の
厚みＬｃが１５オングストローム以上のものが用いられ
る。しかしながら、ｄ002 が３．４２〜３．７０オング
ストローム、Ｌｃが１５〜３００オングストロームのも
のは電池の放電容量が大きくなる点で好ましい。またｄ
002 が３．３５〜３．４２オングストローム、Ｌｃが３
００オングストローム以上のものは電池の放電容量は小
さいものの、放電電圧が一定で安定している特徴があ
る。The vapor-grown carbon fiber used in the present invention has a crystal interlayer distance d 002 of (002) plane of 3.35 to 3.70 angstroms by X-ray diffraction, and a thickness Lc of the crystal layer of 15 angstroms or more. Is used. However, those having d 002 of 3.42 to 3.70 angstroms and Lc of 15 to 300 angstroms are preferable in that the discharge capacity of the battery is increased. Also d
002 is 3.35 to 3.42 angstroms, Lc is 3.
Those having a thickness of 00 Å or more have a characteristic that the discharge voltage is constant and stable although the discharge capacity of the battery is small.
【００２８】[0028]
【実施例】図１に示すようなボタン形非水電解液電池を
つぎのような手順で試作した。EXAMPLE A button-type non-aqueous electrolyte battery as shown in FIG. 1 was prototyped by the following procedure.
【００２９】繊維径が平均０．８μｍ、長さが平均４０
μｍ、Ｘ線回折法による（００２）面の結晶層間距離ｄ
002 が３．５２オングストローム、同じく結晶層の厚み
Ｌｃが４０オングストロームの気相成長炭素繊維（日機
装株式会社製グラファイトウイスカー：商品名グラスカ
ー）を様々な程度に酸化処理し、それらにポリテトラフ
ルオロエチレン（ＰＴＦＥ）を５ｗｔ％添加したものを
０．１２ｇ採集し、３２５ｍｅｓｈのＳＵＳ３１６金網
に包み込んで半径１０ｍｍで厚さが２ｍｍの円板状に加
圧成形し、減圧下で２００℃で６時間乾燥して炭素電極
（１）を得た。The average fiber diameter is 0.8 μm and the average length is 40.
μm, distance d between crystal layers of (002) plane by X-ray diffraction method
Vapor-grown carbon fibers (Graphite whisker manufactured by Nikkiso Co., Ltd .: trade name: glass car) having 3.52 Å of 002 and the thickness Lc of the crystal layer of 40 Å are oxidized to various degrees, and polytetrafluoroethylene 0.12 g of (PTFE) added at 5 wt% was collected, wrapped in a 325 mesh SUS316 wire mesh, pressed into a disk having a radius of 10 mm and a thickness of 2 mm, and dried at 200 ° C. under reduced pressure for 6 hours. Thus, a carbon electrode (1) was obtained.
【００３０】７０ｗｔ％のＬｉＣｏＯ2 （平均粒径１．
３μｍ）、２０ｗｔ％のアセチレンブラックおよび１０
ｗｔ％のポリテトラフルオロエチレン（ＰＴＦＥ）を混
合して正極合剤とし、この正極合剤を０．４ｇ採集して
３２５ｍｅｓｈのステンレス製金網に包み込んで径が１
２ｍｍで厚さが２ｍｍの正極板ペレット（２）を得た。
葉脈状の無孔部と、孔が３次元的に配列した有孔部と
を有する平均厚さが２３μｍのポリエチレン製微孔膜を
直径１４ｍｍに打ち抜いた微孔性セパレーター（３）と
ポリプロピレンの不織布を直径１２ｍｍに打ち抜いた平
均厚さが２００μｍの不織布セパレーター（４）を使用
した。70% by weight of LiCoO 2 (average particle size: 1.
3 μm), 20 wt% of acetylene black and 10
wt% polytetrafluoroethylene (PTFE) was mixed to form a positive electrode mixture, 0.4 g of this positive electrode mixture was collected, wrapped in a 325 mesh stainless steel wire mesh, and the diameter was 1
A positive electrode plate pellet (2) having a thickness of 2 mm and a thickness of 2 mm was obtained.
A microporous separator (3) punched out to a diameter of 14 mm from a polyethylene microporous membrane having an average thickness of 23 μm and having non-porous portions in the form of veins and perforated portions in which holes are three-dimensionally arranged, and a nonwoven fabric of polypropylene Was punched out to a diameter of 12 mm, and a nonwoven fabric separator (4) having an average thickness of 200 μm was used.
【００３１】これらに有機電解液を含浸した。ここでは
電解質として１．５モルの過塩素酸リチウムを用いた。
他の好適な電解質として６フッ化リン酸リチウム、６フ
ッ化ヒ酸リチウム、４フッ化ホウ酸リチウムまたはトリ
フロロメタスルフォン酸リチウムのそれぞれ単体もしく
は混合物、または過塩素酸リチウムとの混合物を使用し
ても良い。また、本実施例では溶媒にアセトニトリルと
エチレンカーボネートを体積比で３：１に混合したもの
を用いた。他の好適な溶媒としてはプロピレンカーボネ
ート、２メチルテトラヒドロフラン、テトラヒドロフラ
ン、ジオキソラン、２メチルジオキソラン、４メチルジ
オキソラン、γブチロラクトンまたはジメトキシエタン
の単体もしくは混合物、またはエチレンカーボネートお
よびアセトニトリルとの混合物等がある。These were impregnated with an organic electrolyte. Here, 1.5 mol of lithium perchlorate was used as the electrolyte.
Other suitable electrolytes are lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate or lithium trifluorometasulfonate, each alone or as a mixture, or a mixture with lithium perchlorate. May be. In this example, a mixture of acetonitrile and ethylene carbonate at a volume ratio of 3: 1 was used as a solvent. Other suitable solvents include propylene carbonate, 2 methyl tetrahydrofuran, tetrahydrofuran, dioxolane, 2 methyl dioxolane, 4 methyl dioxolane, gamma butyrolactone or a mixture of dimethoxyethane, or a mixture with ethylene carbonate and acetonitrile.
【００３２】上記の電池構成物を耐食性ステンレス鋼板
製の正極缶（５）および負極缶（６）、およびポリプロ
ピレン製の絶縁ガスケット（７）からなる電池ケースに
収納して直径が１５．４ｍｍで厚さが４．８ｍｍの非水
電解質二次電池を試作した。これらの電池を２ｍＡの充
電電流で４．０Ｖまで充電し、また２ｍＡの放電電流で
２．８Ｖまで放電した。その結果、表面積に対する酸化
処理面積の比率が増加するに従って放電容量は増加し、
１５〜２０％のときにそれは最大を示した。そして、そ
の後は徐々に低下し、６０％を越えると酸化処理の効果
はなくなり、逆に結晶構造が崩れてしまい未酸化処理品
よりも放電容量は低下した。これらの代表例を次の表１
に示す。The above battery component was housed in a battery case comprising a positive electrode can (5) and a negative electrode can (6) made of a corrosion-resistant stainless steel plate and an insulating gasket (7) made of polypropylene, and had a diameter of 15.4 mm and a thickness of 15.4 mm. A non-aqueous electrolyte secondary battery having a length of 4.8 mm was prototyped. These batteries were charged to 4.0 V with a charging current of 2 mA and discharged to 2.8 V with a discharging current of 2 mA. As a result, the discharge capacity increases as the ratio of the oxidized area to the surface area increases,
It showed a maximum at 15-20%. After that, it gradually decreased, and when it exceeded 60%, the effect of the oxidation treatment was lost, and conversely, the crystal structure was broken and the discharge capacity was lower than that of the unoxidized product. These typical examples are shown in Table 1 below.
Shown in
【００３３】[0033]
【表１】 （Ａ）は酸化処理により表面積の１５％に孔を開けたも
のである。（Ｂ）は（Ａ）の酸化処理を施していないも
の。（Ｃ）は表面積の５％に孔を開けたもので、（Ｄ）
は表面積の６０％まで孔を開けたものである。[Table 1] (A) is a hole in which 15% of the surface area is formed by an oxidation treatment. (B) does not undergo the oxidation treatment of (A). (C) shows a hole in 5% of the surface area, and (D)
Is the one in which pores are formed up to 60% of the surface area.
【００３４】これらの電池のうち、代表例として（Ａ）
と（Ｂ）の放電容量とサイクル数を図２に示す。Of these batteries, a typical example is (A)
FIG. 2 shows the discharge capacity and the number of cycles for (B) and (B).
【００３５】図２から明らかなように本発明による酸化
処理を施した（Ａ）は、酸化処理を施していない（Ｂ）
と比較して放電容量が約２５％増加した。また、サイク
ル特性も安定している。表面積に占める孔の割合が５％
以上になると本特許の酸化処理の効果が表れ始め、１５
〜２０％で最大の効果が得られる。その効果は孔の割合
の増加と共に徐々に減少し、６０％より大きくなると実
用上の効果は認められなくなる。As is clear from FIG. 2, the oxidized (A) according to the present invention is not oxidized (B).
, The discharge capacity increased by about 25%. Also, the cycle characteristics are stable. Percentage of pores in surface area is 5%
Then, the effect of the oxidation treatment of the present invention starts to appear,
The maximum effect is obtained at 20%. The effect gradually decreases with an increase in the percentage of holes, and when it exceeds 60%, no practical effect is recognized.
【００３６】図３には代表として（Ａ）、（Ｂ）の走査
型電子顕微鏡写真を示す。明らかに炭素繊維の断面に酸
化処理によるの孔が存在するのがわかる。FIG. 3 shows scanning electron micrographs of (A) and (B) as representatives. It can be clearly seen that pores formed by the oxidation treatment exist in the cross section of the carbon fiber.
【００３７】なお、気相成長炭素繊維を負極に用いたボ
タン型有機電解質二次電池における炭素繊維の側面に酸
化処理を施すことの効果は、円筒形、角形またはペーパ
ー形電池においても同様に得られる。また、電解質にポ
リエチレンオキサイドなどの固体電解質を用いた場合に
も同様である。The effect of oxidizing the side surfaces of carbon fibers in a button-type organic electrolyte secondary battery using a vapor-grown carbon fiber as a negative electrode is similarly obtained in a cylindrical, square or paper battery. Can be The same applies when a solid electrolyte such as polyethylene oxide is used as the electrolyte.
【００３８】[0038]
【発明の効果】本発明により、エネルギー密度の高い
（放電容量が大きい）気相成長炭素繊維を得ることがで
き、非水電解質二次電池のエネルギー密度を向上させる
ことができる。According to the present invention, a vapor grown carbon fiber having a high energy density (having a large discharge capacity) can be obtained, and the energy density of a non-aqueous electrolyte secondary battery can be improved.
【図１】本発明の非水電解質電池の一例であるボタン型
電池の内部構造を示した図。FIG. 1 is a diagram showing an internal structure of a button-type battery which is an example of a non-aqueous electrolyte battery of the present invention.
【図２】気相成長炭素繊維の酸化処理の有無が非水電解
質電池の放電容量およびサイクル特性におよぼす影響を
示した図。FIG. 2 is a diagram showing the influence of the presence or absence of oxidation treatment on vapor-grown carbon fibers on the discharge capacity and cycle characteristics of a nonaqueous electrolyte battery.
【図３】本発明の酸化処理を施す前後の気相成長炭素繊
維の形状を表した図（走査型電子顕微鏡写真）。FIG. 3 is a view (scanning electron micrograph) showing the shape of a vapor-grown carbon fiber before and after performing the oxidation treatment of the present invention.
１ 炭素電極 ２ 正極板ペレット ３ 微孔性セパレーター ４ 不織布セパレーター ５ 正極缶 ６ 負極缶 ７ 絶縁ガスケット Reference Signs List 1 carbon electrode 2 positive electrode plate pellet 3 microporous separator 4 nonwoven fabric separator 5 positive electrode can 6 negative electrode can 7 insulating gasket
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭63−121248（ＪＰ，Ａ) 特開 昭63−58763（ＪＰ，Ａ) 特開 平１−275415（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01M 4/02 - 4/04 H01M 4/58 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-121248 (JP, A) JP-A-63-58763 (JP, A) JP-A-1-275415 (JP, A) (58) Investigation Field (Int.Cl. 7 , DB name) H01M 4/02-4/04 H01M 4/58
Claims (1)
０．５〜１０００μｍである気相成長炭素繊維を用いた
非水電解質二次電池用負極であって、該気相成長炭素繊
維の表面は酸化処理により繊維表面面積の５〜６０％に
平均孔径が０．０１〜２．５μｍである孔が開孔されて
おり、比表面積は１００ｍ2 ／ｇ以下であることを特徴
とする非水電解質二次電池用負極。1. A negative electrode for a non-aqueous electrolyte secondary battery using a vapor-grown carbon fiber having a diameter of 0.1 to 5.0 μm and a length of 0.5 to 1000 μm. On the surface of the grown carbon fiber, pores having an average pore diameter of 0.01 to 2.5 μm are opened in 5 to 60% of the fiber surface area by oxidation treatment, and the specific surface area is 100 m 2 / g or less. Characteristic negative electrode for non-aqueous electrolyte secondary batteries.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19249591A JP3262566B2 (en) | 1991-07-05 | 1991-07-05 | Negative electrode for non-aqueous electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19249591A JP3262566B2 (en) | 1991-07-05 | 1991-07-05 | Negative electrode for non-aqueous electrolyte secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0757724A JPH0757724A (en) | 1995-03-03 |
| JP3262566B2 true JP3262566B2 (en) | 2002-03-04 |
Family
ID=16292259
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19249591A Expired - Fee Related JP3262566B2 (en) | 1991-07-05 | 1991-07-05 | Negative electrode for non-aqueous electrolyte secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3262566B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08315820A (en) * | 1995-05-11 | 1996-11-29 | Petoca:Kk | Carbon fiber for secondary battery negative electrode material and manufacture thereof |
-
1991
- 1991-07-05 JP JP19249591A patent/JP3262566B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0757724A (en) | 1995-03-03 |
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