JPWO2013124950A1 - Lithium ion battery - Google Patents

Lithium ion battery Download PDF

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JPWO2013124950A1
JPWO2013124950A1 JP2014500765A JP2014500765A JPWO2013124950A1 JP WO2013124950 A1 JPWO2013124950 A1 JP WO2013124950A1 JP 2014500765 A JP2014500765 A JP 2014500765A JP 2014500765 A JP2014500765 A JP 2014500765A JP WO2013124950 A1 JPWO2013124950 A1 JP WO2013124950A1
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negative electrode
weight
lithium ion
ion battery
polycarboxylic acid
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JP5855737B2 (en
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明秀 田中
明秀 田中
西村　悦子
悦子 西村
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Hitachi Astemo Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
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    • H01M4/366—Composites as layered products
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

本発明は、エネルギー密度が高く、高温保存性、及びサイクル駆動時の耐久性に優れたリチウムイオン電池を提供することを課題とする。負極集電体；及び前記負極集電体上に配置された、負極活物質と水溶性多糖類と高分子ポリカルボン酸とを含む負極合剤層；を含むリチウムイオン電池用負極であって、前記負極合剤層が前記水溶性多糖類及び前記高分子ポリカルボン酸を合計で０．９〜１．７重量％含み、前記水溶性多糖類の重量に対する前記高分子ポリカルボン酸の重量の比が０．０２〜０．２５である前記リチウムイオン電池用負極により上記課題を解決することができる。An object of the present invention is to provide a lithium ion battery having high energy density, excellent high-temperature storage stability, and durability during cycle driving. A negative electrode current collector; and a negative electrode mixture layer disposed on the negative electrode current collector and including a negative electrode active material, a water-soluble polysaccharide, and a polymer polycarboxylic acid; The negative electrode mixture layer includes the water-soluble polysaccharide and the polymer polycarboxylic acid in a total amount of 0.9 to 1.7% by weight, and the ratio of the weight of the polymer polycarboxylic acid to the weight of the water-soluble polysaccharide. The above-mentioned problem can be solved by the negative electrode for a lithium ion battery having a value of 0.02 to 0.25.

Description

本発明は、リチウムイオン電池用負極、及び前記負極を含むリチウムイオン電池に関する。   The present invention relates to a negative electrode for a lithium ion battery, and a lithium ion battery including the negative electrode.

リチウムイオン電池は、高いエネルギー密度を有するため、例えば鉄道、自動車等の車両搭載用途、又は太陽光発電若しくは風力発電等で発電した電力を蓄え、電力系統に供給する用途等に用いられる電池として注目されている。例えば、リチウムイオン電池（以下、適宜「電池」と言う）を搭載する自動車としては、エンジンを搭載しないゼロエミッション電気自動車、エンジンと二次電池の両方を搭載したハイブリッド電気自動車、さらには系統電源から直接充電するプラグインハイブリッド電気自動車等がある。また、電力系統が遮断された非常時に電力を供給する定置式電力貯蔵システムとしての用途も期待されている。   Lithium-ion batteries have a high energy density, so they are attracting attention as batteries used for on-board applications such as railways and automobiles, or for applications that store electric power generated by solar power generation or wind power generation and supply it to an electric power system. Has been. For example, automobiles equipped with lithium-ion batteries (hereinafter referred to as “batteries” where appropriate) include zero-emission electric cars equipped with no engine, hybrid electric cars equipped with both an engine and a secondary battery, and system power supplies. There are plug-in hybrid electric vehicles that charge directly. In addition, it is expected to be used as a stationary power storage system that supplies power in an emergency when the power system is cut off.

このような多様な用途の中で、高出力特性及び高エネルギー密度を持つリチウムイオン電池が求められている。   Among such various uses, lithium ion batteries having high output characteristics and high energy density are required.

また、電池に対して優れた耐久性も要求されている。例えば、環境温度が高くなったり、充放電サイクルを繰り返したりしても、充電可能な電池容量（即ち電池容量）の減少率が低く、長期にわたって電池容量維持率が高いことが要求されている。また、路面からの輻射熱あるいは車内からの熱伝導のため、例えば６０℃以上の高温環境における保存特性及びサイクル寿命が重要な要求性能となっている。しかしながら、リチウムイオン電池は、高温環境下にて放置したり、充放電サイクルを行ったりすることで、電池容量が低下する。   Also, excellent durability is required for the battery. For example, even if the environmental temperature becomes high or the charge / discharge cycle is repeated, the reduction rate of the rechargeable battery capacity (that is, battery capacity) is low, and the battery capacity maintenance rate is required to be high over a long period of time. Further, because of radiant heat from the road surface or heat conduction from the inside of the vehicle, for example, storage characteristics and cycle life in a high temperature environment of 60 ° C. or higher are important required performances. However, the battery capacity of a lithium ion battery is reduced by being left in a high temperature environment or performing a charge / discharge cycle.

このような事情に鑑み、特許文献１は、ポリ（メタ）アクリル酸のリチウム塩とカルボキシメチルセルロースのナトリウム塩（以下、適宜「ＣＭＣ」という）とからなるリチウムイオン電池電極用バインダーを用いる技術を開示している。この技術を用いて、乾燥段階で容易に水分を除去し、かつ充放電サイクル特性に優れた電池を得ることを目的としている。   In view of such circumstances, Patent Document 1 discloses a technique using a binder for a lithium ion battery electrode comprising a lithium salt of poly (meth) acrylic acid and a sodium salt of carboxymethyl cellulose (hereinafter referred to as “CMC” as appropriate). doing. An object of the present invention is to obtain a battery that easily removes moisture in the drying stage and has excellent charge / discharge cycle characteristics.

また、特許文献２は、ポリアクリル酸塩及び水溶性高分子（ＣＭＣを含む）を含有し、前記ポリアクリル酸塩の添加量が負極合剤全重量に対して０．１重量％以上０．５重量％以下、前記水溶性高分子の添加量が負極合剤全重量に対して０．３重量％以上０．５重量％以下であることを特徴とする非水電解質二次電池を開示している。この技術を用いて、水溶性高分子（ＣＭＣ）の総量を減らし、高出力特性を有する電池を提供することを目的としている。   Patent Document 2 contains a polyacrylate and a water-soluble polymer (including CMC), and the addition amount of the polyacrylate is 0.1% by weight or more to the total weight of the negative electrode mixture. Disclosed is a non-aqueous electrolyte secondary battery, wherein the water-soluble polymer is added in an amount of 5% by weight or less and 0.3% by weight or more and 0.5% by weight or less based on the total weight of the negative electrode mixture. ing. An object of the present invention is to provide a battery having high output characteristics by reducing the total amount of water-soluble polymer (CMC) using this technique.

さらに、特許文献３は、負極用炭素の表面を水溶性高分子で被覆することを特徴とするリチウム二次電池を開示している。この技術を用いて、初期充放電時に負極表面で溶媒が分解して生じる不可逆容量を低減し、高エネルギー密度の電池を提供することを目的としている。   Further, Patent Document 3 discloses a lithium secondary battery characterized in that the surface of carbon for negative electrode is coated with a water-soluble polymer. An object of the present invention is to provide a battery having a high energy density by reducing the irreversible capacity generated by the decomposition of the solvent on the negative electrode surface during the initial charge / discharge.

また、特許文献４は、バインダーとしてポリアクリル酸を黒鉛負極に用いる技術を開示している。この技術を用いることで、プロピレンカーボネート（ＰＣ）電解液中でも作動可能な電池を提供することができる。   Patent Document 4 discloses a technique using polyacrylic acid as a binder for a graphite negative electrode. By using this technique, a battery that can operate even in a propylene carbonate (PC) electrolyte can be provided.

特開２００２−５０３６０号公報JP 2002-50360 A 特開２００２−３０４９８６号公報JP 2002-304986 A 特開平１１−１２０９９２号公報JP-A-11-129992 特開２００２−１３４１７１号公報JP 2002-134171 A

リチウムイオン電池では、初期充放電、高温環境下での放置、充放電サイクルにより電池容量が低下する。この電池容量の低下は、負極の結着力が小さい場合や、黒鉛表面で電解液が分解しやすい場合に顕著に起きる。   In a lithium ion battery, the battery capacity decreases due to initial charge / discharge, standing in a high temperature environment, and charge / discharge cycles. This decrease in battery capacity occurs remarkably when the binding force of the negative electrode is small or when the electrolyte solution is easily decomposed on the graphite surface.

本発明は上記の課題を解決するためのものであり、その目的は、エネルギー密度が高く、高温保存性、及びサイクル駆動時の耐久性に優れたリチウムイオン電池を提供することである。   The present invention is for solving the above-described problems, and an object thereof is to provide a lithium ion battery having high energy density, excellent high-temperature storage stability, and durability during cycle driving.

高分子ポリカルボン酸は、黒鉛等の負極活物質の表面を被覆し、電解液の分解を抑制することに優れていたが、特許文献４のように、黒鉛を高分子ポリカルボン酸のみで被覆すると硬い膜が形成される。黒鉛は充放電の際に膨張収縮するため、形成された膜が硬いと膨張収縮に追随できず、サイクル特性が低下してしまう。   The polymer polycarboxylic acid was excellent in covering the surface of the negative electrode active material such as graphite and suppressing the decomposition of the electrolytic solution. However, as in Patent Document 4, the graphite is coated only with the polymer polycarboxylic acid. Then, a hard film is formed. Since graphite expands and contracts during charge and discharge, if the formed film is hard, it cannot follow expansion and contraction, and cycle characteristics deteriorate.

この問題を解決するために、高分子ポリカルボン酸に加えて水溶性多糖類を使用したが、特許文献１及び２に示されているような量を用いても良好な結果を得ることはできなかった。本発明者らがこの原因を詳細に調査した結果、黒鉛上に被覆構造が十分形成されていないことを発見した。また、高分子ポリカルボン酸及び水溶性多糖類の使用量及び使用比率によって、黒鉛の被覆構造に大きな違いが生じることを発見した。   In order to solve this problem, water-soluble polysaccharides were used in addition to the high-molecular polycarboxylic acid, but good results could be obtained even if the amounts shown in Patent Documents 1 and 2 were used. There wasn't. As a result of detailed investigation of this cause by the present inventors, it has been found that a coating structure is not sufficiently formed on graphite. Moreover, it discovered that the coating | coated structure of a graphite produced a big difference with the usage-amount and usage-amount of high molecular polycarboxylic acid and water-soluble polysaccharide.

そこで、本発明者らが鋭意検討した結果、特定の量及び比率の高分子ポリカルボン酸及び水溶性多糖類を用いて負極活物質を被覆することにより、十分な被覆構造を形成することができ、その結果、高温保存性、及びサイクル駆動時の耐久性を向上できることを見出した。   Therefore, as a result of intensive studies by the present inventors, a sufficient coating structure can be formed by coating the negative electrode active material with a specific amount and ratio of a high molecular weight polycarboxylic acid and a water-soluble polysaccharide. As a result, it was found that high temperature storage stability and durability during cycle driving can be improved.

すなわち、本発明は以下の発明を包含する。   That is, the present invention includes the following inventions.

（１）負極集電体；及び
前記負極集電体上に配置された、負極活物質と水溶性多糖類と高分子ポリカルボン酸又はその誘導体とを含む負極合剤層；
を含むリチウムイオン電池用負極であって、
前記負極合剤層が前記水溶性多糖類と前記高分子ポリカルボン酸又はその誘導体とを合計で０．９〜１．７重量％含み、
前記水溶性多糖類の重量に対する前記高分子ポリカルボン酸又はその誘導体の重量の比が０．０２〜０．２５である、前記リチウムイオン電池用負極。(1) a negative electrode current collector; and a negative electrode mixture layer comprising a negative electrode active material, a water-soluble polysaccharide, and a polymer polycarboxylic acid or a derivative thereof disposed on the negative electrode current collector;
A negative electrode for a lithium ion battery comprising:
The negative electrode mixture layer includes the water-soluble polysaccharide and the polymer polycarboxylic acid or a derivative thereof in a total amount of 0.9 to 1.7% by weight,
The negative electrode for a lithium ion battery, wherein a ratio of the weight of the polymer polycarboxylic acid or its derivative to the weight of the water-soluble polysaccharide is 0.02 to 0.25.

（２）負極合剤層が更に非フッ素系有機重合体を含む、（１）に記載のリチウムイオン電池用負極。 (2) The negative electrode for a lithium ion battery according to (1), wherein the negative electrode mixture layer further contains a non-fluorine organic polymer.

（３）水溶性多糖類と高分子ポリカルボン酸又はその誘導体との合計の重量に対する非フッ素系有機重合体の重量の比が０．５５〜１．４５である、（２）に記載のリチウムイオン電池用負極。 (3) The lithium according to (2), wherein the ratio of the weight of the non-fluorinated organic polymer to the total weight of the water-soluble polysaccharide and the polymer polycarboxylic acid or derivative thereof is 0.55 to 1.45. Negative electrode for ion battery.

（４）高分子ポリカルボン酸又はその誘導体がポリアクリル酸、ポリメタクリル酸、又はそれらの塩若しくはエステルである、（１）〜（３）のいずれかに記載のリチウムイオン電池用負極。 (4) The negative electrode for a lithium ion battery according to any one of (1) to (3), wherein the polymer polycarboxylic acid or a derivative thereof is polyacrylic acid, polymethacrylic acid, or a salt or ester thereof.

（５）高分子ポリカルボン酸又はその誘導体がポリアクリル酸の塩である、（１）〜（４）のいずれかに記載のリチウムイオン電池用負極。 (5) The negative electrode for a lithium ion battery according to any one of (1) to (4), wherein the polymer polycarboxylic acid or a derivative thereof is a salt of polyacrylic acid.

（６）負極活物質が０．３３４５〜０．３３８ｎｍの層間距離（ｄ００２）を有する黒鉛である、（１）〜（５）のいずれかに記載のリチウムイオン電池用負極。(6) The negative electrode for a lithium ion battery according to any one of (1) to (5), wherein the negative electrode active material is graphite having an interlayer distance (d 002 ) of 0.3345 to 0.338 nm.

（７）負極合剤層が水溶性多糖類と高分子ポリカルボン酸又はその誘導体とを合計で１．０〜１．３重量％含み、水溶性多糖類の重量に対する高分子ポリカルボン酸又はその誘導体の重量の比が０．１〜０．１５である、（１）〜（６）のいずれかに記載のリチウムイオン電池用負極。 (7) The negative electrode mixture layer contains 1.0 to 1.3% by weight in total of the water-soluble polysaccharide and the polymer polycarboxylic acid or a derivative thereof, and the polymer polycarboxylic acid or its weight relative to the weight of the water-soluble polysaccharide The negative electrode for a lithium ion battery according to any one of (1) to (6), wherein the weight ratio of the derivative is 0.1 to 0.15.

（８）（１）〜（７）のいずれかに記載のリチウムイオン電池用負極を含むリチウムイオン電池。 (8) A lithium ion battery comprising the negative electrode for a lithium ion battery according to any one of (1) to (7).

本発明により、高温保存、及びサイクル駆動時の耐久性に優れたリチウムイオン電池用負極及びリチウムイオン電池を提供することができる。   According to the present invention, it is possible to provide a negative electrode for a lithium ion battery and a lithium ion battery excellent in high temperature storage and durability during cycle driving.

本発明の実施例で作製したリチウムイオン電池の断面図である。It is sectional drawing of the lithium ion battery produced in the Example of this invention.

以下、本発明を実施するための形態（以下、適宜「本実施形態」と言う）を詳細に説明するが、本実施形態は以下の内容に限定されるものではなく、その要旨を逸脱しない範囲内で任意に変更して実施することができる。   Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment” as appropriate) will be described in detail. However, the present embodiment is not limited to the following contents and does not depart from the gist of the present invention. It can carry out by changing arbitrarily within.

本発明は、負極活物質と水溶性多糖類と高分子ポリカルボン酸又はその誘導体（例えば、塩及びエステル）とを含む負極合剤層を含むリチウムイオン電池用負極に関する。   The present invention relates to a negative electrode for a lithium ion battery including a negative electrode mixture layer including a negative electrode active material, a water-soluble polysaccharide, and a polymer polycarboxylic acid or a derivative thereof (for example, a salt and an ester).

水溶性多糖類と高分子ポリカルボン酸の合計量は、負極合剤全重量に対して０．９重量％以上１．７重量％以下である。この数値範囲内であると、負極活物質の表面は水溶性多糖類及び高分子ポリカルボン酸によって十分に複合被覆される。なお、負極合剤全重量とは、乾燥後の負極合剤層に含まれる固形分の合計重量を意味し、スラリー調製時に使用される溶媒の重量を含むものではない。０．９重量％未満では、量が少ないため負極活物質表面をうまく被覆することができない。そのため、負極活物質が膨張収縮した際に被覆構造を維持することができず、高温保存特性やサイクル特性が低下する。一方、１．７重量％を超えると、水溶性多糖類と高分子ポリカルボン酸が凝集し、顕著に厚膜化してしまうため、高温保存特性やサイクル特性が低下する。水溶性多糖類と高分子ポリカルボン酸の添加量の合計は、０．９５重量％以上１．５重量％以下が好ましく、１．０重量％以上１．３重量％以下が特に好ましい。   The total amount of the water-soluble polysaccharide and the polymer polycarboxylic acid is 0.9% by weight or more and 1.7% by weight or less based on the total weight of the negative electrode mixture. Within this numerical range, the surface of the negative electrode active material is sufficiently composite-coated with the water-soluble polysaccharide and the polymer polycarboxylic acid. The total weight of the negative electrode mixture means the total weight of solids contained in the dried negative electrode mixture layer, and does not include the weight of the solvent used at the time of slurry preparation. If the amount is less than 0.9% by weight, the surface of the negative electrode active material cannot be satisfactorily covered because the amount is small. Therefore, the coating structure cannot be maintained when the negative electrode active material expands and contracts, and the high-temperature storage characteristics and cycle characteristics deteriorate. On the other hand, if it exceeds 1.7% by weight, the water-soluble polysaccharide and the high-molecular polycarboxylic acid aggregate and remarkably thicken, so that the high-temperature storage characteristics and cycle characteristics deteriorate. The total addition amount of the water-soluble polysaccharide and the polymer polycarboxylic acid is preferably 0.95% by weight or more and 1.5% by weight or less, and particularly preferably 1.0% by weight or more and 1.3% by weight or less.

水溶性多糖類の重量に対する高分子ポリカルボン酸の重量の比（高分子ポリカルボン酸／水溶性多糖類）は０．０２以上０．２５以下である。この数値範囲内であると、負極活物質の表面は水溶性多糖類及び高分子ポリカルボン酸によって十分に複合被覆される。高分子ポリカルボン酸／水溶性多糖類が０．２５を超えると、水溶性多糖類と高分子ポリカルボン酸が凝集したり、混練の際等に高分子ポリカルボン酸が析出してしまう。この理由は明確ではないが、水溶性多糖類と高分子ポリカルボン酸が相互作用することに起因すると考えられる。高分子ポリカルボン酸／水溶性多糖類は、０．０５以上０．２以下が好ましく、０．１以上０．１５以下が特に好ましい。   The ratio of the weight of the polymer polycarboxylic acid to the weight of the water-soluble polysaccharide (polymer polycarboxylic acid / water-soluble polysaccharide) is 0.02 or more and 0.25 or less. Within this numerical range, the surface of the negative electrode active material is sufficiently composite-coated with the water-soluble polysaccharide and the polymer polycarboxylic acid. When the polymer polycarboxylic acid / water-soluble polysaccharide exceeds 0.25, the water-soluble polysaccharide and the polymer polycarboxylic acid are aggregated, or the polymer polycarboxylic acid is precipitated during kneading. The reason for this is not clear, but is thought to be due to the interaction between the water-soluble polysaccharide and the high-molecular polycarboxylic acid. The polymer polycarboxylic acid / water-soluble polysaccharide is preferably from 0.05 to 0.2, particularly preferably from 0.1 to 0.15.

水溶性多糖類及び高分子ポリカルボン酸の量及び比率は、いずれも上記の範囲内である必要がある。いずれか一方が上記範囲外となると、負極活物質表面がうまく被覆されず、負極活物質が膨張収縮した際に被覆構造を維持することができない。これにより、高温保存特性やサイクル特性が低下する。   The amounts and ratios of the water-soluble polysaccharide and the high-molecular polycarboxylic acid need to be within the above ranges. If either one is out of the above range, the surface of the negative electrode active material is not well coated, and the coating structure cannot be maintained when the negative electrode active material expands and contracts. Thereby, a high temperature storage characteristic and cycling characteristics fall.

本発明における水溶性多糖類としては、メチルセルロース、エチルセルロース、アセチルセルロース、ヒドロキシエチルセルロース、カルボキシメチルセルロース、でんぷん、カラギナン、プルラン、グアーガム、ザンサンガム(キサンタンガム)、ヒドロキシプロピルセルロース、ヒドロキシプロピルメチルセルロース等が挙げられる。これらのうち、一部を塩にしてもよい。この中では、特にカルボキシメチルセルロースのナトリウム塩が好ましい。これらの化合物は単独で使用してもよいし、２種以上を組み合わせて使用してもよい。   Examples of the water-soluble polysaccharide in the present invention include methylcellulose, ethylcellulose, acetylcellulose, hydroxyethylcellulose, carboxymethylcellulose, starch, carrageenan, pullulan, guar gum, xanthan gum (xanthan gum), hydroxypropylcellulose, hydroxypropylmethylcellulose and the like. Some of these may be salted. Among these, a sodium salt of carboxymethyl cellulose is particularly preferable. These compounds may be used alone or in combination of two or more.

本発明における高分子ポリカルボン酸は、カルボキシル基を有するモノマーを重合することにより得られる高分子である。高分子ポリカルボン酸及びその誘導体としては、ポリアクリル酸、ポリアクリル酸塩、ポリアクリル酸エステル、ポリメタクリル酸、ポリメタクリル酸塩、ポリメタクリル酸エステル等を挙げることができる。これらの高分子は、繰り返し単位中に極性の強いカルボキシル基又はその誘導体を持ち、強い結着力を有する。特に限定はされないが、ポリアクリル酸、ポリメタクリル酸、及びそれらのナトリウム塩、カリウム塩、アンモニウム塩、メチルエステル、エチルエステル、ブチルエステル等が挙げられる。これらは単独で用いてもよいし、２種以上を混合あるいは共重合させて用いてもよい。また、塩やエステルでは、全てのカルボキシル基が中和あるいはエステル化されていてもよいし、カルボキシル基が部分的に残存していてもよい。この中では、ポリアクリル酸塩が好ましく、特にナトリウム塩が好ましい。   The polymer polycarboxylic acid in the present invention is a polymer obtained by polymerizing a monomer having a carboxyl group. Examples of the polymer polycarboxylic acid and derivatives thereof include polyacrylic acid, polyacrylate, polyacrylate, polymethacrylic acid, polymethacrylate, and polymethacrylate. These polymers have a strong polar carboxyl group or a derivative thereof in the repeating unit and have a strong binding force. Although it does not specifically limit, polyacrylic acid, polymethacrylic acid, and those sodium salt, potassium salt, ammonium salt, methyl ester, ethyl ester, butyl ester, etc. are mentioned. These may be used alone or in combination of two or more. Moreover, in a salt or ester, all the carboxyl groups may be neutralized or esterified, or the carboxyl groups may partially remain. In this, a polyacrylate is preferable and especially a sodium salt is preferable.

高分子ポリカルボン酸の重量平均分子量は１０００〜１００万が好ましい。更に好ましくは１０万〜１００万である。なお、前記分子量は、液体クロマトグラフィーにより測定した重量平均分子量の値とする。   The weight average molecular weight of the polymeric polycarboxylic acid is preferably 1,000 to 1,000,000. More preferably, it is 100,000-1 million. The molecular weight is a weight average molecular weight value measured by liquid chromatography.

本発明の負極は、負極活物質、水溶性多糖類、高分子ポリカルボン酸、及び集電体を含む。高レート充放電が必要な場合には、導電剤を添加することもある。本発明で使用可能な負極活物質としては、黒鉛、非黒鉛炭素等を選択することができる。   The negative electrode of the present invention includes a negative electrode active material, a water-soluble polysaccharide, a polymer polycarboxylic acid, and a current collector. When high rate charge / discharge is required, a conductive agent may be added. As the negative electrode active material that can be used in the present invention, graphite, non-graphite carbon, or the like can be selected.

負極活物質は黒鉛を含むことが好ましい。黒鉛は、黒鉛層間距離（ｄ００２）が０．３３４５ｎｍ以上０．３３８ｎｍ以下であることが好ましい。このような黒鉛は水溶性多糖類及び高分子ポリカルボン酸に対する濡れ性が良く、水溶性多糖類と高分子ポリカルボン酸の複合被覆がつきやすく、リチウムイオン電池の高温保存特性及びサイクル特性の向上をより大きなものにすることができる。The negative electrode active material preferably contains graphite. The graphite preferably has a graphite interlayer distance (d 002 ) of 0.3345 nm or more and 0.338 nm or less. Such graphite has good wettability to water-soluble polysaccharides and high-molecular polycarboxylic acids, and can easily be combined with water-soluble polysaccharides and high-molecular polycarboxylic acids, improving the high-temperature storage characteristics and cycle characteristics of lithium-ion batteries. Can be made larger.

負極活物質としての黒鉛は、リチウムイオンを化学的に吸蔵・放出可能な天然黒鉛、人造黒鉛、メソフェ−ズ炭素、膨張黒鉛、炭素繊維、気相成長法炭素繊維、ピッチ系炭素質材料、ニードルコークス、石油コークス、及びポリアクリロニトリル系炭素繊維等を原料として製造される。なお、上記の黒鉛層間距離（ｄ００２）は、ＸＲＤ（Ｘ線粉末回折法）（X-Ray Diffraction Method）等を用いて測定することができる。Graphite as the negative electrode active material is natural graphite, artificial graphite, mesophase carbon, expanded graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle capable of chemically occluding and releasing lithium ions. Manufactured from coke, petroleum coke, polyacrylonitrile-based carbon fiber and the like. The graphite interlayer distance (d 002 ) can be measured by using XRD (X-Ray Diffraction Method) or the like.

負極活物質として、リチウムと合金を形成する材料又は金属間化合物を形成する材料を使用してもよい。例えば、アルミニウム、シリコン、スズ等の金属及びこれらの合金、リチウム含有の遷移金属窒化物Ｌｉ（３−ｘ）ＭｘＮ、ケイ素の低級酸化物ＬｉｘＳｉＯｙ（０≦ｘ、０＜ｙ＜２）、及びスズの低級酸化物ＬｉｘＳｎＯｙ（０≦ｘ、０＜ｙ＜２）が挙げられる。上記の材料以外の材料を負極活物質として使用することもできる。As the negative electrode active material, a material that forms an alloy with lithium or a material that forms an intermetallic compound may be used. For example, metals such as aluminum, silicon and tin and alloys thereof, lithium-containing transition metal nitrides Li (3-x) M x N, lower oxides of silicon Li x SiO y (0 ≦ x, 0 <y < 2), and a lower oxide of tin, Li x SnO y (0 ≦ x, 0 <y <2). Materials other than the above materials can also be used as the negative electrode active material.

負極活物質の粒径は、負極活物質及びバインダから形成される合剤層の厚さ以下にすることが望ましい。負極活物質の粉末中に合剤層厚さ以上のサイズを有する粗粒がある場合、予めふるい分級や風流分級等により粗粒を除去し、合剤層の厚さ以下の粒子を使用することが好ましい。   The particle size of the negative electrode active material is desirably set to be equal to or smaller than the thickness of the mixture layer formed of the negative electrode active material and the binder. If there are coarse particles in the negative electrode active material powder having a size larger than the thickness of the mixture layer, remove the coarse particles in advance by sieving, airflow classification, etc., and use particles less than the thickness of the mixture layer Is preferred.

具体的な粒径としては、レーザ回折／散乱式粒度分布測定装置により求めた平均粒径が、３μｍ以上３０μｍ以下であることが好ましく、さらに３μｍ以上２５μｍ以下、特に５μｍ以上２０μｍ以下であることが好ましい。平均粒径が３０μｍを超える場合、電極に凹凸ができやすくなるため、電池特性が低下する場合がある。また、３μｍ未満である場合、黒鉛がつぶれ難くなるため、密度を上げにくくなる傾向がある。なお、粒度分布は界面活性剤を含んだ精製水に試料を分散させ、レーザ回折／散乱式粒度分布測定装置で測定することができ、平均粒径は累積５０％粒径（５０％Ｄ）として算出される。   The specific particle size is preferably 3 μm or more and 30 μm or less, more preferably 3 μm or more and 25 μm or less, and particularly preferably 5 μm or more and 20 μm or less. preferable. When the average particle size exceeds 30 μm, the electrode is likely to be uneven, and the battery characteristics may be deteriorated. On the other hand, when the thickness is less than 3 μm, graphite is not easily crushed, so that the density tends to be difficult to increase. The particle size distribution can be measured by dispersing a sample in purified water containing a surfactant and measuring with a laser diffraction / scattering type particle size distribution measuring device, and the average particle size is 50% cumulative (50% D). Calculated.

また、本発明における負極活物質の黒鉛は、７７Ｋ窒素吸着測定より得られる吸着等温線からＢＥＴ（Brunauer-Emmet-Teller）法を用いて求めた比表面積が、０．１ｍ２／ｇ以上１０ｍ２／ｇ以下であることが好ましい。０．１ｍ２／ｇ未満の場合は、活物質とリチウムイオンとの反応面積が減少するため、充放電特性が悪化する場合がある。また、１０ｍ２／ｇを超える場合は、電解質との反応が起こりやすくなるため、不可逆容量が増大してしまい、寿命特性が悪化する恐れがある。Further, the graphite of the negative electrode active material in the present invention has a specific surface area determined using the BET (Brunauer-Emmet-Teller) method from an adsorption isotherm obtained from the 77K nitrogen adsorption measurements, 0.1 m 2 / g or more 10 m 2 / G or less is preferable. If it is less than 0.1 m 2 / g, the reaction area between the active material and lithium ions decreases, and the charge / discharge characteristics may deteriorate. On the other hand, if it exceeds 10 m 2 / g, the reaction with the electrolyte is likely to occur, so that the irreversible capacity increases and the life characteristics may be deteriorated.

負極の作製方法は、特に限定されるものではないが、例えば、負極活物質、水溶性多糖類、及び高分子ポリカルボン酸を、溶媒中にいれ、ボールミル、プラネタリーミキサー等の一般的な混錬分散方法を用いてよく混練分散して、負極合剤スラリーを作製する。続いて、この負極合剤スラリーを塗布機を用いて銅等の金属箔からなる集電体上に塗布し、例えば１００℃前後の適当な温度にて真空乾燥し、プレス機を用いて圧縮成形した後に所望の大きさに切断又は打ち抜いて、目的の負極を作製することができる。   The method for producing the negative electrode is not particularly limited. For example, a negative electrode active material, a water-soluble polysaccharide, and a polymer polycarboxylic acid are placed in a solvent, and a general mixture such as a ball mill or a planetary mixer is used. A negative electrode mixture slurry is prepared by thoroughly kneading and dispersing using a smelting and dispersing method. Subsequently, this negative electrode mixture slurry is applied onto a current collector made of a metal foil such as copper using an applicator, vacuum dried at an appropriate temperature of, for example, about 100 ° C., and compression molded using a press. Then, the desired negative electrode can be produced by cutting or punching into a desired size.

負極合剤スラリーを調製する際の溶媒としては、特に限定されないが、例えば、純水、Ｎ−メチル−２−ピロリドン（ＮＭＰ）、エチレングリコール、トルエン、キシレン等が挙げられる。この中では、純水が特に好ましい。   Although it does not specifically limit as a solvent at the time of preparing a negative mix slurry, For example, a pure water, N-methyl-2-pyrrolidone (NMP), ethylene glycol, toluene, xylene etc. are mentioned. Among these, pure water is particularly preferable.

さらに、結着剤としてアクリロニトリル−ブタジエンゴム（ＮＢＲ）やスチレン−ブタジエンゴム（ＳＢＲ）等の非フッ素系有機重合体を負極合剤に添加してもよい。高分子ポリカルボン酸及び水溶性多糖類の合計重量に対する非フッ素系有機重合体の重量の比は（非フッ素系有機重合体／高分子ポリカルボン酸＋水溶性多糖類）は、０．５５以上１．４５以下であることが好ましい。０．７以上１．４以下がより好ましく、０．８以上１．２以下が特に好ましい。０．５５未満では、結着力が確保できないためにサイクル劣化が低下する場合がある。また１．４５を超えると、被覆構造の成長を阻害し、高温保存特性やサイクル特性が低下する場合がある。   Further, a non-fluorinated organic polymer such as acrylonitrile-butadiene rubber (NBR) or styrene-butadiene rubber (SBR) may be added to the negative electrode mixture as a binder. The ratio of the weight of the non-fluorine organic polymer to the total weight of the polymer polycarboxylic acid and the water-soluble polysaccharide is (non-fluorine organic polymer / polymer polycarboxylic acid + water-soluble polysaccharide) is 0.55 or more. It is preferable that it is 1.45 or less. 0.7 to 1.4 is more preferable, and 0.8 to 1.2 is particularly preferable. If it is less than 0.55, since the binding force cannot be ensured, cycle deterioration may be reduced. On the other hand, if it exceeds 1.45, the growth of the coating structure may be inhibited, and the high-temperature storage characteristics and cycle characteristics may be deteriorated.

負極の集電体には、厚さが１０〜１００μｍの銅箔、厚さが１０〜１００μｍで孔径０．１〜１０ｍｍの銅製穿孔箔、エキスパンドメタル、又は発泡金属板等が用いられる。銅の他に、ステンレス、チタン、又はニッケル等の材質も適用可能である。本発明では、材質、形状、製造方法等に制限されることなく、任意の集電体を使用することができる。   For the current collector of the negative electrode, a copper foil having a thickness of 10 to 100 μm, a copper perforated foil having a thickness of 10 to 100 μm and a pore diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, or the like is used. In addition to copper, materials such as stainless steel, titanium, or nickel are also applicable. In the present invention, any current collector can be used without being limited by the material, shape, manufacturing method and the like.

負極活物質、バインダ、及び有機溶媒を混合した負極スラリーを、ドクターブレード法、ディッピング法、又はスプレー法等によって集電体へ付着させた後、有機溶媒を乾燥させ、ロールプレスによって加圧成形することにより、負極を作製することができる。また、塗布から乾燥までを複数回行うことにより、多層合剤層を集電体に形成させることも可能である。   A negative electrode slurry in which a negative electrode active material, a binder, and an organic solvent are mixed is attached to a current collector by a doctor blade method, a dipping method, a spray method, or the like, and then the organic solvent is dried and pressure-molded by a roll press. Thereby, a negative electrode can be produced. Moreover, it is also possible to form a multilayer mixture layer on a current collector by carrying out a plurality of times from application to drying.

次に、本発明の負極を適用可能な電池について説明する。以下、本実施形態に係る負極を適用可能な電池（以下、適宜「本実施形態に係る電池」と言う）を、図１を参照しながら具体例を挙げて説明する。ただし、図１に示す電池の構成は、本実施形態に係る負極を適用可能なリチウムイオン電池の内部構造のあくまでも一例である。   Next, a battery to which the negative electrode of the present invention can be applied will be described. Hereinafter, a battery to which the negative electrode according to this embodiment can be applied (hereinafter, referred to as “battery according to this embodiment” as appropriate) will be described with reference to FIG. However, the configuration of the battery shown in FIG. 1 is merely an example of the internal structure of the lithium ion battery to which the negative electrode according to this embodiment can be applied.

図１は、本実施形態に係る電池の内部構造を模式的に表す図である。図１に示す本実施形態に係る電池は、正極１０、セパレータ１１、負極１２、電池容器（電池缶）１３、正極集電タブ１４、負極集電タブ１５、内蓋１６、内圧開放弁１７、ガスケット１８、正温度係数（Ｐｏｓｉｔｉｖｅ ｔｅｍｐｅｒａｔｕｒｅ ｃｏｅｆｆｉｃｉｅｎｔ；ＰＴＣ）抵抗素子１９、及び電池蓋２０、軸心から構成される。電池蓋２０は、内蓋１６、内圧開放弁１７、ガスケット１８、及びＰＴＣ抵抗素子１９からなる一体化部品である。また、軸心には、正極１０、セパレータ１１及び負極１２が捲回されている。   FIG. 1 is a diagram schematically illustrating the internal structure of the battery according to the present embodiment. A battery according to this embodiment shown in FIG. 1 includes a positive electrode 10, a separator 11, a negative electrode 12, a battery container (battery can) 13, a positive electrode current collecting tab 14, a negative electrode current collecting tab 15, an inner lid 16, an internal pressure release valve 17, A gasket 18, a positive temperature coefficient (PTC) resistance element 19, a battery lid 20, and an axial center are included. The battery lid 20 is an integrated part composed of the inner lid 16, the internal pressure release valve 17, the gasket 18, and the PTC resistance element 19. Moreover, the positive electrode 10, the separator 11, and the negative electrode 12 are wound by the shaft center.

正極１０は、正極活物質、導電剤、バインダ、及び集電体から構成される。正極活物質を例示すると、ＬｉＣｏＯ２、ＬｉＮｉＯ２、及びＬｉＭｎ２Ｏ４が代表例である。他に、ＬｉＭｎＯ３、ＬｉＭｎ２Ｏ３、ＬｉＭｎＯ２、Ｌｉ４Ｍｎ５Ｏ１２、ＬｉＭｎ２−ｘＭｘＯ２（ただし、Ｍ＝Ｃｏ、Ｎｉ、Ｆｅ、Ｃｒ、Ｚｎ、Ｔｉからなる群から選ばれる少なくとも１種、ｘ＝０．０１〜０．２）、Ｌｉ２Ｍｎ３ＭＯ８（ただし、Ｍ＝Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎからなる群から選ばれる少なくとも１種）、Ｌｉ１−ｘＡｘＭｎ２Ｏ４（ただし、Ａ＝Ｍｇ、Ｂ、Ａｌ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｒ、Ｚｎ、Ｃａからなる群から選ばれる少なくとも１種、ｘ＝０．０１〜０．１）、ＬｉＮｉ１−ｘＭｘＯ２（ただし、Ｍ＝Ｃｏ、Ｆｅ、Ｇａからなる群から選ばれる少なくとも１種、ｘ＝０．０１〜０．２）、ＬｉＦｅＯ２、Ｆｅ２（ＳＯ４）３、ＬｉＣｏ１−ｘＭｘＯ２（ただし、Ｍ＝Ｎｉ、Ｆｅ、Ｍｎからなる群から選ばれる少なくとも１種、ｘ＝０．０１〜０．２）、ＬｉＮｉ１−ｘＭｘＯ２（ただし、Ｍ＝Ｍｎ、Ｆｅ、Ｃｏ、Ａｌ、Ｇａ、Ｃａ、Ｍｇからなる群から選ばれる少なくとも１種、ｘ＝０．０１〜０．２）、Ｆｅ（ＭｏＯ４）３、ＦｅＦ３、ＬｉＦｅＰＯ４、及びＬｉＭｎＰＯ４等を列挙することができる。The positive electrode 10 includes a positive electrode active material, a conductive agent, a binder, and a current collector. Illustrative examples of the positive electrode active material include LiCoO 2 , LiNiO 2 , and LiMn 2 O 4 . In addition, LiMnO 3 , LiMn 2 O 3 , LiMnO 2 , Li 4 Mn 5 O 12 , LiMn 2−x M x O 2 (where M = Co, Ni, Fe, Cr, Zn, Ti are selected. Li 2 Mn 3 MO 8 (provided that M = at least one selected from the group consisting of Fe, Co, Ni, Cu, Zn), Li 1 − x A x Mn 2 O 4 (provided that, A = Mg, B, Al , Fe, Co, Ni, Cr, Zn, at least one selected from the group consisting of Ca, x = 0.01~0.1), LiNi 1-x M x O 2 ( however, M = Co, Fe, at least one selected from the group consisting of Ga, x = 0.01~0.2), LiFeO 2, Fe 2 (SO 4) 3, LiCo 1-x M x O 2 ( where M = Ni, Fe, at least one selected from the group consisting of Mn, x = 0.01~0.2), LiNi 1-x M x O 2 ( however, M = Mn, Fe, Co , Al, Ga , At least one selected from the group consisting of Ca, Mg, x = 0.01 to 0.2), Fe (MoO 4 ) 3 , FeF 3 , LiFePO 4 , LiMnPO 4 , and the like.

正極活物質の粒径は、正極活物質、導電剤、及びバインダから形成される合剤層の厚さ以下になるように通常は規定される。正極活物質の粉末中に合剤層厚さ以上のサイズを有する粗粒がある場合、予めふるい分級や風流分級等により粗粒を除去し、合剤層厚さ以下の粒子を作製することが好ましい。   The particle size of the positive electrode active material is usually defined so as to be equal to or less than the thickness of the mixture layer formed from the positive electrode active material, the conductive agent, and the binder. When there are coarse particles having a size equal to or greater than the thickness of the mixture layer in the positive electrode active material powder, the coarse particles can be removed in advance by sieving classification or wind classification to produce particles having a thickness of the mixture layer thickness or less. preferable.

また、正極活物質は、一般に酸化物系であるために電気抵抗が高いので、電気伝導性を補うための炭素粉末などの導電剤を利用する。正極活物質及び導電剤はともに通常は粉末であるので、粉末にバインダを混合して、粉末同士を結合させると同時に集電体へ接着させることができる。   In addition, since the positive electrode active material is generally oxide-based and has high electrical resistance, a conductive agent such as carbon powder is used to supplement electrical conductivity. Since both the positive electrode active material and the conductive agent are usually powders, a binder can be mixed with the powders, and the powders can be bonded together and simultaneously bonded to the current collector.

正極１０の集電体には、厚さが１０〜１００μｍのアルミニウム箔、厚さが１０〜１００μｍで孔径が０．１〜１０ｍｍのアルミニウム製穿孔箔、エキスパンドメタル、又は発泡金属板等が用いられる。アルミニウムの他に、ステンレスやチタン等の材質も適用可能である。本発明では、材質、形状、製造方法等に制限されることなく、任意の集電体を使用することができる。   For the current collector of the positive electrode 10, an aluminum foil having a thickness of 10 to 100 μm, an aluminum perforated foil having a thickness of 10 to 100 μm and a pore diameter of 0.1 to 10 mm, an expanded metal, or a metal foam plate is used. . In addition to aluminum, materials such as stainless steel and titanium are also applicable. In the present invention, any current collector can be used without being limited by the material, shape, manufacturing method and the like.

正極活物質、導電剤、バインダ、及び有機溶媒を混合した正極スラリーを、ドクターブレード法、ディッピング法、又はスプレー法等によって集電体へ付着させた後、有機溶媒を乾燥させ、ロールプレスによって加圧成形することにより、正極１０を作製することができる。また、塗布から乾燥までを複数回行うことにより、複数の合剤層を集電体に積層化させることも可能である。   A positive electrode slurry in which a positive electrode active material, a conductive agent, a binder, and an organic solvent are mixed is attached to a current collector by a doctor blade method, a dipping method, or a spray method, and then the organic solvent is dried and applied by a roll press. The positive electrode 10 can be produced by pressure forming. In addition, a plurality of mixture layers can be laminated on the current collector by performing a plurality of times from application to drying.

負極１２としては、上記で説明した負極を使用する。   As the negative electrode 12, the negative electrode described above is used.

以上の方法で作製した正極１０及び負極１２の間にセパレータ１１を挿入し、正極１０及び負極１２の短絡を防止する。セパレータ１１には、ポリエチレン、ポリプロピレン等からなるポリオレフィン系高分子シート、又はポリオレフィン系高分子と４フッ化ポリエチレンを代表とするフッ素系高分子シートを溶着させた２層構造等を使用することが可能である。電池温度が高くなったときにセパレータ１１が収縮しないように、セパレータ１１の表面にセラミックス及びバインダの混合物を薄層状に形成してもよい。これらのセパレータ１１は、電池の充放電時にリチウムイオンを透過させる必要があるため、一般に細孔径が０．０１〜１０μｍ、気孔率が２０〜９０％であればリチウムイオン電池に使用可能である。   The separator 11 is inserted between the positive electrode 10 and the negative electrode 12 produced by the above method to prevent a short circuit between the positive electrode 10 and the negative electrode 12. The separator 11 can be a polyolefin polymer sheet made of polyethylene, polypropylene, or the like, or a two-layer structure in which a polyolefin polymer and a fluorine polymer sheet typified by tetrafluoropolyethylene are welded. It is. A mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator 11 so that the separator 11 does not shrink when the battery temperature increases. Since these separators 11 need to permeate lithium ions during charging / discharging of the battery, they can generally be used for lithium ion batteries if the pore diameter is 0.01 to 10 μm and the porosity is 20 to 90%.

このようなセパレータ１１を正極１０及び負極１２の間に挿入し、軸心に捲回した電極群を作製する。軸心は、正極１０、セパレータ１１及び負極１２を担持できるものであれば、公知の任意のものを用いることができる。電極群は、図１に示した円筒形状の他に、短冊状電極を積層したもの、又は正極１０と負極１２を扁平状等の任意の形状に捲回したもの等、種々の形状にすることができる。電池容器１３の形状は、電極群の形状に合わせ、円筒形、偏平長円形状、扁平楕円形状、角形等の形状を選択してもよい。   Such a separator 11 is inserted between the positive electrode 10 and the negative electrode 12 to produce an electrode group wound around an axis. As the axis, any known one can be used as long as it can carry the positive electrode 10, the separator 11, and the negative electrode 12. In addition to the cylindrical shape shown in FIG. 1, the electrode group has various shapes such as a laminate of strip electrodes, or a positive electrode 10 and a negative electrode 12 wound in an arbitrary shape such as a flat shape. Can do. The shape of the battery case 13 may be selected from shapes such as a cylindrical shape, a flat oval shape, a flat oval shape, and a square shape according to the shape of the electrode group.

電池容器１３の材質は、アルミニウム、ステンレス鋼、ニッケルメッキ鋼等、非水電解質に対し耐食性のある材料から選択される。また、電池容器１３を正極１０又は負極１２に電気的に接続する場合は、非水電解質と接触している部分において、電池容器１３の腐食やリチウムイオンとの合金化による材料の変質が起こらないように、電池容器１３の材料の選定を行う。   The material of the battery container 13 is selected from materials that are corrosion resistant to non-aqueous electrolytes, such as aluminum, stainless steel, and nickel-plated steel. Further, when the battery container 13 is electrically connected to the positive electrode 10 or the negative electrode 12, the material is not deteriorated due to corrosion of the battery container 13 or alloying with lithium ions in the portion in contact with the nonaqueous electrolyte. Thus, the material of the battery container 13 is selected.

電池容器１３に電極群を収納し、電池容器１３の内壁に負極集電タブ１５を接続し、電池蓋２０の底面に正極集電タブ１４を接続する。電解液は、電池の密閉の前に電池容器内部に注入する。電解液の注入方法は、電池蓋２０を解放した状態にて電極群に直接添加する方法、又は電池蓋２０に設置した注入口から添加する方法がある。   The electrode group is housed in the battery container 13, the negative electrode current collecting tab 15 is connected to the inner wall of the battery container 13, and the positive electrode current collecting tab 14 is connected to the bottom surface of the battery lid 20. The electrolyte is injected into the battery container before the battery is sealed. As a method for injecting the electrolyte, there are a method of adding directly to the electrode group in a state where the battery cover 20 is released, or a method of adding from an injection port installed in the battery cover 20.

その後、電池蓋２０を電池容器１３に密着させ、電池全体を密閉する。電解液の注入口がある場合は、それも密封する。電池を密閉する方法には、溶接、かしめ等公知の技術がある。   Thereafter, the battery lid 20 is brought into close contact with the battery container 13 to seal the entire battery. If there is an electrolyte inlet, seal it as well. As a method for sealing the battery, there are known techniques such as welding and caulking.

本発明で使用可能な電解液の代表例として、エチレンカーボネートにジメチルカーボネート、ジエチルカーボネート、又はエチルメチルカーボネート等を混合した溶媒に、電解質として六フッ化リン酸リチウム（ＬｉＰＦ６）、又はホウフッ化リチウム（ＬｉＢＦ４）を溶解させた溶液がある。本発明は、溶媒や電解質の種類、溶媒の混合比に制限されることなく、他の電解液も利用可能である。As a typical example of the electrolytic solution that can be used in the present invention, lithium hexafluorophosphate (LiPF 6 ) or lithium borofluoride as an electrolyte in a solvent obtained by mixing dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate with ethylene carbonate There is a solution in which (LiBF 4 ) is dissolved. The present invention is not limited to the type of solvent and electrolyte, and the mixing ratio of solvents, and other electrolytes can be used.

なお、電解液に使用可能な非水溶媒の例としては、プロピレンカーボネート、エチレンカーボネート、ブチレンカーボネート、ビニレンカーボネート、γ−ブチロラクトン、ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネート、１，２−ジメトキシエタン、２−メチルテトラヒドロフラン、ジメチルスルホキシド、１，３−ジオキソラン、ホルムアミド、ジメチルホルムアミド、プロピオン酸メチル、プロピオン酸エチル、リン酸トリエステル、トリメトキシメタン、ジオキソラン、ジエチルエーテル、スルホラン、３−メチル−２−オキサゾリジノン、テトラヒドロフラン、１、２−ジエトキシエタン、クロルエチレンカーボネート、又はクロルプロピレンカーボネート等を挙げることができる。本発明の電池に内蔵される正極１０又は負極１２上で分解しなければ、これ以外の溶媒を用いてもよい。   Examples of non-aqueous solvents that can be used for the electrolyte include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2 -Methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, ethyl propionate, phosphate triester, trimethoxymethane, dioxolane, diethyl ether, sulfolane, 3-methyl-2-oxazolidinone, Tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, chloropropylene carbonate, and the like can be given. Other solvents may be used as long as they do not decompose on the positive electrode 10 or the negative electrode 12 incorporated in the battery of the present invention.

また、電解質の例としては、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、ＬｉＡｓＦ６、ＬｉＳｂＦ６、又はリチウムトリフルオロメタンスルホンイミドで代表されるリチウムのイミド塩等、多種類のリチウム塩がある。これらの塩を、上記の溶媒に溶解してできた非水電解液を電池用電解液として使用することができる。本実施形態に係る電池が有する正極１０及び負極１２上で分解しなければ、これ以外の電解質を用いてもよい。In addition, examples of the electrolyte, LiPF 6, LiBF 4, LiClO 4, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, or imide salts such as lithium represented by lithium trifluoromethane sulfonimide, multi There are different types of lithium salts. A nonaqueous electrolytic solution obtained by dissolving these salts in the above-mentioned solvent can be used as a battery electrolytic solution. An electrolyte other than this may be used as long as it does not decompose on the positive electrode 10 and the negative electrode 12 included in the battery according to the present embodiment.

固体高分子電解質（ポリマー電解質）を用いる場合には、ポリエチレンオキシド、ポリアクリロニトリル、ポリフッ化ビニリデン、ポリメタクリル酸メチル、ポリヘキサフルオロプロピレン、ポリエチレンオキサイド等のイオン伝導性ポリマーを電解質に用いることができる。これらの固体高分子電解質を用いた場合、セパレータ１１を省略することができる利点がある。   When a solid polymer electrolyte (polymer electrolyte) is used, an ion conductive polymer such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, and polyethylene oxide can be used for the electrolyte. When these solid polymer electrolytes are used, there is an advantage that the separator 11 can be omitted.

さらに、イオン性液体を用いることができる。例えば、１−エチル−３−メチルイミダゾリウムテトラフルオロボレート（ＥＭＩ−ＢＦ４）、リチウム塩ＬｉＮ（ＳＯ２ＣＦ３）２（ＬｉＴＦＳＩ）とトリグライムとテトラグライムとの混合錯体、環状四級アンモニウム系陽イオン（例えば、Ｎ−メチル−Ｎ−プロピルピロリジニウム）、及びイミド系陰イオン（例えば、ビス（フルオロスルホニル）イミド）から、正極１０及び負極１２にて分解しない組み合わせを選択して、本実施形態に係る電池に用いることができる。Furthermore, an ionic liquid can be used. For example, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF 4 ), a lithium salt LiN (SO 2 CF 3 ) 2 (LiTFSI), a mixed complex of triglyme and tetraglyme, a cyclic quaternary ammonium-based positive ion This combination is selected by selecting a combination that does not decompose at the positive electrode 10 and the negative electrode 12 from an ion (for example, N-methyl-N-propylpyrrolidinium) and an imide anion (for example, bis (fluorosulfonyl) imide). It can use for the battery which concerns on a form.

本発明のリチウムイオン電池は、例えば、上述のような負極と正極とをセパレータを介して対向して配置し、電解質を注入することによって製造することができる。本発明のリチウムイオン電池の構造は特に限定されないが、通常、正極及び負極とそれらを隔てるセパレータとを捲回して捲回式電極群にするか、又は正極、負極及びセパレータを積層させて積層型の電極群とすることができる。   The lithium ion battery of the present invention can be manufactured by, for example, disposing the negative electrode and the positive electrode as described above with a separator interposed therebetween and injecting an electrolyte. The structure of the lithium ion battery of the present invention is not particularly limited. Usually, the positive electrode and the negative electrode and the separator separating them are wound into a wound electrode group, or the positive electrode, the negative electrode and the separator are stacked to form a stacked type. Electrode group.

以上説明した電池を用いることにより、高温保存特性、サイクル特性に優れた電池を提供することが可能である。   By using the battery described above, it is possible to provide a battery having excellent high-temperature storage characteristics and cycle characteristics.

以下、実施例及び比較例を示して本発明をさらに詳細に説明する。なお、以下の実施例は一例であり、これらに限定されるものではない。   Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the following Examples are examples and are not limited to these.

（実施例１）
以下の手順に従って負極活物質を合成した。まずオートクレーブを用いて、石炭系コールタールを４００℃で熱処理し、生コークスを得た。この生コークスを粉砕した後、２８００℃にて不活性雰囲気中でカ焼を行い、黒鉛層間距離（ｄ００２）が０．３３５０ｎｍの黒鉛を得た。この黒鉛を分級機付きの衝撃破砕機を用いて粉砕し、３００メッシュの篩にて粗粉を除去して黒鉛粒子とした。その際の平均粒径は１７．２μｍであり、比表面積は１．６ｍ２／ｇであった。Example 1
A negative electrode active material was synthesized according to the following procedure. First, coal-based coal tar was heat-treated at 400 ° C. using an autoclave to obtain raw coke. The raw coke was pulverized and calcined at 2800 ° C. in an inert atmosphere to obtain graphite having a graphite interlayer distance (d 002 ) of 0.3350 nm. This graphite was pulverized using an impact crusher equipped with a classifier, and coarse particles were removed with a 300 mesh sieve to obtain graphite particles. At that time, the average particle diameter was 17.2 μm and the specific surface area was 1.6 m 2 / g.

続いて、以下の手順に従って正極活物質を合成した。原料として酸化ニッケル、酸化マンガン、及び酸化コバルトを使用し、原子比でＮｉ：Ｍｎ：Ｃｏ比が１：１：１となるように秤量し、湿式粉砕機で粉砕混合した。次に、結着剤としてポリビニルアルコール（ＰＶＡ）を加えた粉砕混合粉を噴霧乾燥機で造粒した。得られた造粒粉末を高純度アルミナ容器に入れ、ＰＶＡを蒸発させるため６００℃で１２時間の仮焼成を行い、空冷後解砕した。さらに、解砕粉にＬｉ：遷移金属（Ｎｉ、Ｍｎ、Ｃｏ）の原子比が１：１となるよう水酸化リチウム一水和物を添加し、充分混合した。この混合粉末を高純度アルミナ容器に入れて９００℃で６時間の本焼成を行った。得られた正極活物質をボールミルで解砕分級した。この正極活物質の平均粒径は６μｍであった。   Subsequently, a positive electrode active material was synthesized according to the following procedure. Nickel oxide, manganese oxide, and cobalt oxide were used as raw materials, weighed so that the Ni: Mn: Co ratio was 1: 1: 1 by atomic ratio, and pulverized and mixed with a wet pulverizer. Next, the pulverized mixed powder to which polyvinyl alcohol (PVA) was added as a binder was granulated with a spray dryer. The obtained granulated powder was put in a high-purity alumina container, pre-baked at 600 ° C. for 12 hours to evaporate PVA, crushed after air cooling. Further, lithium hydroxide monohydrate was added to the pulverized powder so that the atomic ratio of Li: transition metal (Ni, Mn, Co) was 1: 1 and mixed well. This mixed powder was put into a high-purity alumina container and subjected to main firing at 900 ° C. for 6 hours. The obtained positive electrode active material was pulverized and classified with a ball mill. The average particle diameter of this positive electrode active material was 6 μm.

本実施例において、黒鉛の（００２）面の面間隔ｄ００２は、リガク社製Ｘ線回折装置ＲＵ２００Ｂを用いて測定した。Ｘ線源には、ＣｕＫα線（λ＝０．１５４１８ｎｍ）を用い、回折角度はＳｉを用いて補正を行った。測定により得たピークをプロファイルフィッティングすることにより、ブラッグの式を用いて算出することができる。In this embodiment, the surface spacing d 002 of (002) plane of graphite was measured using an X-ray diffraction apparatus RU200B manufactured by Rigaku Corporation. CuKα rays (λ = 0.15418 nm) were used as the X-ray source, and the diffraction angle was corrected using Si. By performing profile fitting on the peak obtained by measurement, it can be calculated using the Bragg equation.

実施例における材料の粒径（５０％Ｄ）は、堀場製作所社製レーザ回折／散乱式粒度分布測定装置ＬＡ−９２０を用いて調べた。光源としては、Ｈｅ−Ｎｅレーザ１ｍＷを用い、黒鉛粒子の分散媒はイオン交換水に界面活性剤を２滴いれたものとした。予め５分以上超音波処理を行い、さらに測定中も超音波処理を行って、凝集を防ぎつつ測定を行った。測定結果の累積５０％粒径（５０％Ｄ）を平均粒径とした。   The particle size (50% D) of the material in the examples was examined using a laser diffraction / scattering particle size distribution measuring apparatus LA-920 manufactured by Horiba, Ltd. A He—Ne laser 1 mW was used as a light source, and a dispersion medium of graphite particles was obtained by adding two drops of a surfactant to ion exchange water. The ultrasonic treatment was performed for 5 minutes or more in advance, and the ultrasonic treatment was also performed during the measurement, and the measurement was performed while preventing aggregation. The cumulative 50% particle size (50% D) of the measurement results was taken as the average particle size.

実施例におけるリチウムイオン電池の負極活物質である黒鉛の比表面積は、黒鉛を１２０℃で３時間真空乾燥した後、日本ベル社製ＢＥＬＳＯＲＰ−ｍｉｎｉを用い、７７Ｋでの窒素吸着を用いて平衡時間３００秒で測定した吸着等温線をＢＥＴ法で解析して求めた。   The specific surface area of graphite, which is the negative electrode active material of the lithium ion battery in the examples, was equilibrated using nitrogen adsorption at 77K using BELSORP-mini manufactured by Nippon Bell Co., Ltd. after vacuum drying of graphite at 120 ° C. for 3 hours. The adsorption isotherm measured at 300 seconds was obtained by analyzing by the BET method.

次に、以下のようにしてリチウムイオン電池を作製した。図１は、本実施例のリチウムイオン電池の断面図を示す図である。図１において、１０は正極、１１はセパレータ、１２は負極、１３は電池缶、１４は正極タブ、１５は負極タブ、１６は内蓋、１７は内圧開放弁、１８はガスケット、１９はＰＴＣ素子、２０は電池蓋を表している。   Next, a lithium ion battery was produced as follows. FIG. 1 is a cross-sectional view of the lithium ion battery of this example. In FIG. 1, 10 is a positive electrode, 11 is a separator, 12 is a negative electrode, 13 is a battery can, 14 is a positive electrode tab, 15 is a negative electrode tab, 16 is an inner lid, 17 is an internal pressure release valve, 18 is a gasket, and 19 is a PTC element. , 20 represents a battery lid.

まず、正極を作製した。正極活物質８６．０重量部に、導電材として粉末状炭素とアセチレンブラックをそれぞれ６．０重量部と２．０重量部加え、予め結着剤として６．０重量部のＰＶＤＦをＮＭＰに溶解した溶液を加えて、さらにプラネタリ−ミキサーで混合し正極合剤スラリーを調製した。このスラリーを、厚さ２０μｍのアルミニウム箔からなる集電体の両面に塗布機で均一かつ均等に塗布した。塗布後、ロールプレス機により圧縮成形し、正極とした。   First, a positive electrode was produced. Add 6.0 parts by weight and 2.0 parts by weight of powdered carbon and acetylene black as conductive materials to 86.0 parts by weight of the positive electrode active material, respectively, and pre-dissolve 6.0 parts by weight of PVDF in NMP as a binder. The prepared solution was added and further mixed with a planetary mixer to prepare a positive electrode mixture slurry. This slurry was uniformly and evenly applied to both surfaces of a current collector made of an aluminum foil having a thickness of 20 μm by a coating machine. After the application, compression molding was performed with a roll press to obtain a positive electrode.

次に、負極を作製した。負極活物質としての前記黒鉛９７．９重量部に、ポリアクリル酸（重量平均分子量５０万）３％水溶液の固形分０．１重量部相当量と、ＣＭＣの１％水溶液の固形分１．０重量部相当量と、ＳＢＲの４０％水溶液の固形分１重量部相当量を加え、さらにプラネタリ−ミキサーで混合し負極合剤スラリーを調製した。このスラリーを、厚さ１０μｍの圧延銅箔からなる集電体の両面に塗布機で均一かつ均等に塗布した。塗布後、ロールプレス機で圧縮成形し、負極とした。   Next, a negative electrode was produced. 97.9 parts by weight of graphite as a negative electrode active material, 0.1 part by weight of solid content of 3% aqueous solution of polyacrylic acid (weight average molecular weight 500,000), and 1.0% solid content of 1% aqueous solution of CMC An equivalent amount by weight and an equivalent amount of 1 part by weight of a solid content of a 40% aqueous solution of SBR were added and further mixed by a planetary mixer to prepare a negative electrode mixture slurry. This slurry was uniformly and evenly applied to both surfaces of a current collector made of a rolled copper foil having a thickness of 10 μm by a coating machine. After the application, it was compression molded with a roll press to obtain a negative electrode.

そして、正極と負極を所望の大きさに裁断し、合剤層の未塗布部にそれぞれ集電タブを超音波溶接した。集電タブとして、正極にはアルミニウムのリード片、負極にはニッケルのリード片をそれぞれ用いた。その後、多孔性のポリエチレンフィルムからなる厚み３０μｍのセパレータを正極及び負極で挟みながら捲回した。この捲回体を電池缶に挿入し、負極タブを電池缶の缶底に抵抗溶接により接続し、正極タブには正極蓋を超音波溶接により接続した。次に、体積比エチレンカーボネート（ＥＣ）：ジメチルカーボネート（ＤＭＣ）：ジエチルカーボネート（ＤＥＣ）＝１：１：１の混合溶媒に、１ｍｏｌ／ｌのＬｉＰＦ６を溶解させた電解質を注液し、その後、正極蓋を電池缶にかしめて密封し、目的のリチウムイオン電池を得た。And the positive electrode and the negative electrode were cut | judged to the desired magnitude | size, and the current collection tab was ultrasonically welded to the uncoated part of the mixture layer, respectively. As the current collecting tab, an aluminum lead piece was used for the positive electrode and a nickel lead piece was used for the negative electrode. Thereafter, a separator having a thickness of 30 μm made of a porous polyethylene film was wound while being sandwiched between the positive electrode and the negative electrode. The wound body was inserted into the battery can, the negative electrode tab was connected to the bottom of the battery can by resistance welding, and the positive electrode lid was connected to the positive electrode tab by ultrasonic welding. Next, an electrolyte in which 1 mol / l LiPF 6 was dissolved in a mixed solvent of volume ratio ethylene carbonate (EC): dimethyl carbonate (DMC): diethyl carbonate (DEC) = 1: 1: 1 was injected, and then The positive electrode lid was caulked and sealed in a battery can to obtain the target lithium ion battery.

作製した電池を常温（２５℃）前後で０．３ＣＡ相当の電流で４．２０Ｖまで充電し、その後４．２０Ｖで電流が０．０３Ｃになるまで定電圧充電を行った。３０分休止後に０．３ＣＡ相当の定電流で３．０Ｖまで定電流放電を行った。これを４サイクル行って初期化し、４サイクル目の電池容量を測定し、測定された電池容量を初期電池容量とした。初期電池容量は１．１５Ａｈであった。   The manufactured battery was charged to 4.20 V at a current equivalent to 0.3 CA at around normal temperature (25 ° C.), and then constant voltage charging was performed until the current reached 0.03 C at 4.20 V. After a 30-minute pause, constant current discharge was performed up to 3.0 V with a constant current corresponding to 0.3 CA. This was initialized by performing 4 cycles, and the battery capacity at the 4th cycle was measured, and the measured battery capacity was defined as the initial battery capacity. The initial battery capacity was 1.15 Ah.

次に、２５℃で、５００回の充放電サイクルを行った。各サイクルにおいては、１Ｃ相当の電流で４．２０Ｖまで充電し、その後４．２０Ｖで電流が０．０３Ｃになるまで定電圧充電を行った。放電は、１Ｃ相当の電流で２．７Ｖまで放電した。充放電の間には休止を３０分行った。電池容量の測定は上記の通り行った。   Next, 500 charge / discharge cycles were performed at 25 ° C. In each cycle, the battery was charged to 4.20 V with a current corresponding to 1 C, and then constant voltage charging was performed until the current became 0.03 C at 4.20 V. Discharge was discharged to 2.7 V with a current corresponding to 1 C. During charging and discharging, a pause was performed for 30 minutes. The battery capacity was measured as described above.

以上の得られた結果を用いて、下記式に従って、サイクル容量維持率を算出した。その結果を表１に示す。   The cycle capacity retention rate was calculated according to the following formula using the obtained results. The results are shown in Table 1.

サイクル容量維持率（％）＝（５００サイクル後の電池容量）／（初期電池容量）
また、５０℃で、保存試験を行った。０．３ＣＡ相当の電流で４．２０Ｖまで充電し、その後４．２０Ｖで電流が０．０３Ｃになるまで定電圧充電を行った。３０分休止後、５０℃の恒温槽にて３ヶ月間保管した。保管後、恒温槽より取り出して、２５℃前後で３時間放置後容量を測定した。電池容量の測定は上記の通り行った。Cycle capacity retention rate (%) = (battery capacity after 500 cycles) / (initial battery capacity)
Moreover, the storage test was done at 50 degreeC. The battery was charged to 4.20 V with a current corresponding to 0.3 CA, and then constant voltage charging was performed until the current became 0.03 C at 4.20 V. After a 30-minute rest, it was stored in a 50 ° C. constant temperature bath for 3 months. After storage, the sample was taken out from the thermostat and allowed to stand at around 25 ° C. for 3 hours, and then the capacity was measured. The battery capacity was measured as described above.

以上の得られた結果を用いて、下記式に従って、保存容量維持率を算出した。その結果を表１に示す。   The storage capacity retention rate was calculated according to the following formula using the results obtained above. The results are shown in Table 1.

保存容量維持率（％）＝（３ケ月保管後の電池容量）／（初期電池容量）
（実施例２）
黒鉛の混合量を９７．９５重量部に、ポリアクリル酸の混合量を０．０５重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。Storage capacity retention rate (%) = (Battery capacity after 3 months storage) / (Initial battery capacity)
(Example 2)
The cycle capacity retention ratio and storage capacity retention ratio were calculated in the same manner as in Example 1 except that the graphite mixing amount was changed to 97.95 parts by weight and the polyacrylic acid mixing amount was changed to 0.05 parts by weight. did. The results are shown in Table 1.

（実施例３）
黒鉛の混合量を９７．８重量部に、ポリアクリル酸の混合量を０．２重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Example 3)
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the amount of graphite was changed to 97.8 parts by weight and the amount of polyacrylic acid was changed to 0.2 parts by weight. did. The results are shown in Table 1.

（実施例４）
黒鉛の混合量を９８．１重量部に、ＣＭＣの混合量を０．８重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。Example 4
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the graphite mixing amount was changed to 98.1 parts by weight and the CMC mixing amount was changed to 0.8 parts by weight. The results are shown in Table 1.

（実施例５）
黒鉛の混合量を９７．４重量部に、ポリアクリル酸の混合量を０．２重量部に、ＣＭＣの混合量を１．４重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Example 5)
Except that the mixing amount of graphite was changed to 97.4 parts by weight, the mixing amount of polyacrylic acid was changed to 0.2 parts by weight, and the mixing amount of CMC was changed to 1.4 parts by weight, the same as in Example 1. The cycle capacity maintenance rate and the storage capacity maintenance rate were calculated. The results are shown in Table 1.

（実施例６）
黒鉛の混合量を９７．３重量部に、ポリアクリル酸の混合量を０．３重量部に、ＣＭＣの混合量を１．４重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Example 6)
Except that the mixing amount of graphite was changed to 97.3 parts by weight, the mixing amount of polyacrylic acid was changed to 0.3 parts by weight, and the mixing amount of CMC was changed to 1.4 parts by weight, the same as in Example 1. The cycle capacity maintenance rate and the storage capacity maintenance rate were calculated. The results are shown in Table 1.

（比較例１）
黒鉛の混合量を９８．０重量部に、ポリアクリル酸の混合量を０重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 1)
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the amount of graphite was changed to 98.0 parts by weight and the amount of polyacrylic acid was changed to 0 parts by weight. The results are shown in Table 1.

（比較例２）
黒鉛の混合量を９７．９９重量部に、ポリアクリル酸の混合量を０．０１重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 2)
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the amount of graphite was changed to 97.9 parts by weight and the amount of polyacrylic acid was changed to 0.01 parts by weight. did. The results are shown in Table 1.

（比較例３）
黒鉛の混合量を９７．５重量部に、ポリアクリル酸の混合量を０．５重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 3)
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the graphite mixing amount was changed to 97.5 parts by weight and the polyacrylic acid mixing amount was changed to 0.5 parts by weight. did. The results are shown in Table 1.

（比較例４）
黒鉛の混合量を９７．０重量部に、ポリアクリル酸の混合量を１．０重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 4)
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the amount of graphite was changed to 97.0 parts by weight and the amount of polyacrylic acid was changed to 1.0 parts by weight. did. The results are shown in Table 1.

（比較例５）
黒鉛の混合量を９７．２重量部に、ポリアクリル酸の混合量を０．４重量部に、ＣＭＣの混合量を１．４重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 5)
Except that the mixing amount of graphite was changed to 97.2 parts by weight, the mixing amount of polyacrylic acid was changed to 0.4 parts by weight, and the mixing amount of CMC was changed to 1.4 parts by weight, the same as in Example 1. The cycle capacity maintenance rate and the storage capacity maintenance rate were calculated. The results are shown in Table 1.

（比較例６）
黒鉛の混合量を９８．４重量部に、ポリアクリル酸の混合量を０．１重量部に、ＣＭＣの混合量を０．５重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 6)
Except for changing the mixing amount of graphite to 98.4 parts by weight, the mixing amount of polyacrylic acid to 0.1 parts by weight, and the mixing amount of CMC to 0.5 parts by weight, the same as in Example 1. The cycle capacity maintenance rate and the storage capacity maintenance rate were calculated. The results are shown in Table 1.

（比較例７）
黒鉛の混合量を９８．３重量部に、ポリアクリル酸の混合量を０．２重量部に、ＣＭＣの混合量を０．５重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 7)
The same procedure as in Example 1 except that the amount of graphite was changed to 98.3 parts by weight, the amount of polyacrylic acid was changed to 0.2 parts by weight, and the amount of CMC was changed to 0.5 parts by weight. The cycle capacity maintenance rate and the storage capacity maintenance rate were calculated. The results are shown in Table 1.

（比較例８）
ポリアクリル酸の混合量を０．５重量部に、ＣＭＣの混合量を０．５重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。(Comparative Example 8)
The cycle capacity retention ratio and the storage capacity retention ratio were calculated in the same manner as in Example 1 except that the polyacrylic acid mixing amount was changed to 0.5 parts by weight and the CMC mixing amount was changed to 0.5 parts by weight. did. The results are shown in Table 1.

（比較例９）
ポリアクリル酸の混合量を１．０重量部に、ＣＭＣの混合量を０重量部に変更した事以外は、実施例１と同様にして、サイクル容量維持率及び保存容量維持率を算出した。その結果を表１に示す。

Figure 2013124950
(Comparative Example 9)
The cycle capacity retention rate and the storage capacity retention rate were calculated in the same manner as in Example 1 except that the polyacrylic acid mixing amount was changed to 1.0 part by weight and the CMC mixing amount was changed to 0 part by weight. The results are shown in Table 1.

Figure 2013124950

表１に示すように、ＣＭＣに対するポリアクリル酸の重量比が０．０２〜０．２５の範囲内であり、且つポリアクリル酸及びＣＭＣの合計量が０．９〜１．７重量％の範囲内であると、サイクル容量維持率（サイクル特性）及び保存容量維持率（高温保存特性）が向上した。   As shown in Table 1, the weight ratio of polyacrylic acid to CMC is in the range of 0.02 to 0.25, and the total amount of polyacrylic acid and CMC is in the range of 0.9 to 1.7% by weight. Within the range, the cycle capacity retention ratio (cycle characteristics) and the storage capacity retention ratio (high temperature storage characteristics) were improved.

（実施例７）
ポリアクリル酸をポリアクリル酸のナトリウム塩に変更して負極を作製したこと以外は実施例１と同様に行った。

Figure 2013124950
(Example 7)
The same procedure as in Example 1 was conducted except that the negative electrode was produced by changing polyacrylic acid to a sodium salt of polyacrylic acid.

Figure 2013124950

表２に示すように、ポリアクリル酸に代えてポリアクリル酸ナトリウム塩を使用することにより、サイクル容量維持率及び保存容量維持率が共に向上した。   As shown in Table 2, both the cycle capacity retention rate and the storage capacity retention rate were improved by using polyacrylic acid sodium salt instead of polyacrylic acid.

以上のように、本発明のリチウムイオン電池は、従来技術と比較して、高温保存特性、及びサイクル特性に優れている。   As described above, the lithium ion battery of the present invention is superior in high-temperature storage characteristics and cycle characteristics as compared with the prior art.

本明細書で引用した全ての刊行物、特許及び特許出願をそのまま参考として本明細書に取り入れるものとする。   All publications, patents and patent applications cited herein are incorporated herein by reference in their entirety.

１０ 正極
１１ セパレータ
１２ 負極
１３ 電池缶
１４ 正極タブ
１５ 負極タブ
１６ 内蓋
１７ 内圧開放弁
１８ ガスケット
１９ ＰＴＣ素子
２０ 電池蓋DESCRIPTION OF SYMBOLS 10 Positive electrode 11 Separator 12 Negative electrode 13 Battery can 14 Positive electrode tab 15 Negative electrode tab 16 Inner cover 17 Internal pressure release valve 18 Gasket 19 PTC element 20 Battery cover

Claims (8)

負極集電体；及び
前記負極集電体上に配置された、負極活物質と水溶性多糖類と高分子ポリカルボン酸又はその誘導体とを含む負極合剤層；
を含むリチウムイオン電池用負極であって、
前記負極合剤層が前記水溶性多糖類と前記高分子ポリカルボン酸又はその誘導体とを合計で０．９〜１．７重量％含み、
前記水溶性多糖類の重量に対する前記高分子ポリカルボン酸又はその誘導体の重量の比が０．０２〜０．２５である、前記リチウムイオン電池用負極。A negative electrode current collector; and a negative electrode mixture layer comprising a negative electrode active material, a water-soluble polysaccharide, and a polymer polycarboxylic acid or a derivative thereof disposed on the negative electrode current collector;
A negative electrode for a lithium ion battery comprising:
The negative electrode mixture layer includes the water-soluble polysaccharide and the polymer polycarboxylic acid or a derivative thereof in a total amount of 0.9 to 1.7% by weight,
The negative electrode for a lithium ion battery, wherein a ratio of the weight of the polymer polycarboxylic acid or its derivative to the weight of the water-soluble polysaccharide is 0.02 to 0.25. 負極合剤層が更に非フッ素系有機重合体を含む、請求項１に記載のリチウムイオン電池用負極。   The negative electrode for a lithium ion battery according to claim 1, wherein the negative electrode mixture layer further contains a non-fluorine organic polymer. 水溶性多糖類と高分子ポリカルボン酸又はその誘導体との合計の重量に対する非フッ素系有機重合体の重量の比が０．５５〜１．４５である、請求項２に記載のリチウムイオン電池用負極。   3. The lithium ion battery according to claim 2, wherein the ratio of the weight of the non-fluorinated organic polymer to the total weight of the water-soluble polysaccharide and the high molecular weight polycarboxylic acid or derivative thereof is 0.55 to 1.45. Negative electrode. 高分子ポリカルボン酸又はその誘導体がポリアクリル酸、ポリメタクリル酸、又はそれらの塩若しくはエステルである、請求項１〜３のいずれかに記載のリチウムイオン電池用負極。   The negative electrode for a lithium ion battery according to any one of claims 1 to 3, wherein the polymer polycarboxylic acid or a derivative thereof is polyacrylic acid, polymethacrylic acid, or a salt or ester thereof. 高分子ポリカルボン酸又はその誘導体がポリアクリル酸の塩である、請求項１〜４のいずれかに記載のリチウムイオン電池用負極。   The negative electrode for a lithium ion battery according to any one of claims 1 to 4, wherein the polymer polycarboxylic acid or a derivative thereof is a salt of polyacrylic acid. 負極活物質が０．３３４５〜０．３３８ｎｍの層間距離（ｄ００２）を有する黒鉛である、請求項１〜５のいずれかに記載のリチウムイオン電池用負極。The negative electrode for a lithium ion battery according to claim 1, wherein the negative electrode active material is graphite having an interlayer distance (d 002 ) of 0.3345 to 0.338 nm. 負極合剤層が水溶性多糖類と高分子ポリカルボン酸又はその誘導体とを合計で１．０〜１．３重量％含み、水溶性多糖類の重量に対する高分子ポリカルボン酸又はその誘導体の重量の比が０．１〜０．１５である、請求項１〜６のいずれかに記載のリチウムイオン電池用負極。   The negative electrode mixture layer contains 1.0 to 1.3% by weight of the water-soluble polysaccharide and the polymer polycarboxylic acid or a derivative thereof in total, and the weight of the polymer polycarboxylic acid or the derivative thereof with respect to the weight of the water-soluble polysaccharide The negative electrode for a lithium ion battery according to claim 1, wherein the ratio is from 0.1 to 0.15. 請求項１〜７のいずれかに記載のリチウムイオン電池用負極を含むリチウムイオン電池。   The lithium ion battery containing the negative electrode for lithium ion batteries in any one of Claims 1-7.
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