JP6344740B2 - ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, ITS MANUFACTURING METHOD, AND LITHIUM ION SECONDARY BATTERY - Google Patents

ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, ITS MANUFACTURING METHOD, AND LITHIUM ION SECONDARY BATTERY Download PDF

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JP6344740B2
JP6344740B2 JP2014533007A JP2014533007A JP6344740B2 JP 6344740 B2 JP6344740 B2 JP 6344740B2 JP 2014533007 A JP2014533007 A JP 2014533007A JP 2014533007 A JP2014533007 A JP 2014533007A JP 6344740 B2 JP6344740 B2 JP 6344740B2
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川崎　卓
卓 川崎
崇人 今井
崇人 今井
裕輝 名古
裕輝 名古
峻 園田
峻 園田
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Denki Kagaku Kogyo KK
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
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    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
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    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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    • Y02E60/10—Energy storage using batteries

Description

本発明は、リチウムイオン二次電池用電極材、その製造方法及びリチウムイオン二次電池に関する。より詳しくは、リチウムイオン二次電池の高容量化技術に関する。   The present invention relates to an electrode material for a lithium ion secondary battery, a manufacturing method thereof, and a lithium ion secondary battery. More specifically, the present invention relates to a technology for increasing the capacity of a lithium ion secondary battery.

リチウムイオンの吸蔵及び放出が可能な材料により負極を形成したリチウムイオン二次電池は、金属リチウムにより負極を形成したリチウム電池に比べて、デンドライドの析出を抑制することができる。このため、リチウムイオン二次電池は、電池の短絡を防止して安全性を高めた上で、高容量でエネルギー密度が高い電池を提供できるという利点を有している。   A lithium ion secondary battery in which a negative electrode is formed of a material capable of occluding and releasing lithium ions can suppress the precipitation of dendride compared to a lithium battery in which a negative electrode is formed of metallic lithium. For this reason, the lithium ion secondary battery has an advantage that a battery having a high capacity and a high energy density can be provided while safety is improved by preventing a short circuit of the battery.

近年、このリチウムイオン二次電池は、さらなる高容量化が求められる一方で、パワー系用途の電池として、電池抵抗の低減による大電流充放電性能の向上が求められている。そこで、従来、電池反応物質であるリチウム金属酸化物正極材や炭素系負極材自体の高容量化、これら反応物質粒子の小粒径化、粒子比表面積や電池設計による電極面積の増加、さらにはセパレータの薄形化による液拡散抵抗の低減などの工夫がなされてきた。   In recent years, while this lithium ion secondary battery is required to have a higher capacity, as a battery for power applications, an improvement in large current charge / discharge performance by reducing battery resistance is required. Therefore, in the past, the capacity of lithium metal oxide positive electrode materials and carbon-based negative electrode materials themselves, which are battery reactants, increased the particle size of these reactant particles, increased the specific electrode surface area due to particle specific surface area and battery design, Ingenuity has been made such as reducing the liquid diffusion resistance by thinning the separator.

しかしながら、これらの工夫は、小粒径化や比表面積の増加によるバインダーの増加を招くため、結果として高容量化に逆行したり、正・負極材が集電体である金属箔から剥離・脱落して電池内部短絡を生じることがある。このような問題を解決するため、バインダー種類を変更し、箔との結着性を増加させる検討がなされているが、この方法は、電池容量は増大できるものの抵抗低減による大電流充放電特性の改善という点では不十分である。   However, these devices lead to an increase in binder due to a reduction in particle size and an increase in specific surface area. As a result, the capacity increases, and the positive and negative electrode materials are peeled off from the metal foil as a current collector. Battery internal short circuit may occur. In order to solve such a problem, studies have been made to change the binder type and increase the binding property with the foil, but this method can increase the battery capacity, but the large current charge / discharge characteristics by reducing the resistance. In terms of improvement, it is insufficient.

このため、従来のリチウムイオン二次電池は、ニッケル・カドミウム電池やニッケル水素電池などの二次電池と比較して大電流充放電特性が劣っており、これが大きな性能障壁となり、大電流充放電が必要とされる電動工具やハイブリッドカー用途への展開は困難であった。このリチウムイオン二次電池の大電流充放電化に関しては、例えばカーボン導電材を用いることにより電極抵抗の低減を図る技術が提案されている（例えば、特許文献１参照。）。   For this reason, conventional lithium ion secondary batteries have poor large current charge / discharge characteristics compared to secondary batteries such as nickel-cadmium batteries and nickel metal hydride batteries. It has been difficult to develop the required power tools and hybrid cars. With regard to the charging / discharging of the lithium ion secondary battery with a large current, for example, a technique for reducing electrode resistance by using a carbon conductive material has been proposed (for example, see Patent Document 1).

一方、近年、安全性とコスト重視の観点から、リチウムイオン二次電池用の正極材としてオリビン型リン酸鉄リチウム（ＬｉＦｅＰＯ４）が注目されつつあるが、この材料は、抵抗が大きいため、低抵抗化が大きな課題となっている（例えば、特許文献２参照。）。そこで、従来、オリビン型リン酸鉄リチウムが有する低抵抗化の課題を解決するため、オリビン型リン酸鉄リチウムと、導電材料である黒鉛を複合化させて電極材とする種々の検討がなされている（例えば、特許文献３，４参照。）。On the other hand, in recent years, olivine-type lithium iron phosphate (LiFePO 4 ) has been attracting attention as a positive electrode material for lithium ion secondary batteries from the viewpoint of safety and cost emphasis. Resistance is a major issue (see, for example, Patent Document 2). Therefore, in order to solve the problem of low resistance of olivine-type lithium iron phosphate, various studies have been made to combine olivine-type lithium iron phosphate and graphite, which is a conductive material, into electrode materials. (For example, see Patent Documents 3 and 4).

特開２００５−１９３９９号公報JP 2005-19399 A 特表２０００−５０９１９３号公報JP 2000-509193 A 特開２００２−７５３６４号公報JP 2002-75364 A 特開２０１１−１０８５２２号公報JP 2011-108522 A

しかしながら、特許文献１に記載のリチウムイオン二次電池は、大電流による充放電サイクルを繰り返すと正・負極材の膨張収縮により正・負極間粒子の導電パスが損なわれ、結果として早期に大電流が流せなくなってしまうという問題がある。一方、オリビン型リン酸鉄リチウムを用いた電極材については、黒鉛の複合化により電極材の性能は向上するが、オリビン型リン酸鉄リチウムは体積当たりの容量が他の活物質と比較して小さいため、高容量化には自ずと限界がある。   However, in the lithium ion secondary battery described in Patent Document 1, when the charge / discharge cycle with a large current is repeated, the conductive path of the positive / negative electrode particles is impaired due to the expansion / contraction of the positive / negative electrode material. There is a problem that will not be able to flow. On the other hand, regarding the electrode material using olivine type lithium iron phosphate, the performance of the electrode material is improved by combining graphite, but the capacity per volume of olivine type lithium iron phosphate is higher than that of other active materials. Since it is small, there is a limit to increasing the capacity.

そこで、本発明は、大電流充放電を寿命中長きに亘って維持することができ、かつ高容量のリチウムイオン二次電池を実現することが可能なリチウムイオン二次電池用電極材、その製造方法及びリチウムイオン二次電池を提供することを主目的とする。   Accordingly, the present invention provides an electrode material for a lithium ion secondary battery that can maintain a large current charge / discharge for a long period of time and can realize a high-capacity lithium ion secondary battery, and its production The main object is to provide a method and a lithium ion secondary battery.

本発明に係るリチウムイオン二次電池用電極材は、活物質及び導電材を含有するリチウムイオン二次電池用電極材であって、前記活物質はリチウム含有複合酸化物、錫酸化物又はシリコン酸化物であり、前記導電材は、非晶質炭素、カーボンナノチューブ及びカーボンブラックであり、前記非晶質炭素により前記活物質の表面の一部又は全部が被覆されているものである。
前記非晶質炭素による前記活物質表面の被覆率は、例えば１０〜９５％とすることができる。
前記非晶質炭素は、有機物の熱分解物でもよい。
本発明のリチウムイオン二次電池用電極材を正極材に用いる場合、前記活物質としては、例えばＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉＯ２、Ｌｉ（ＭｎａＮｉｂＣｏｃ）Ｏ２（但し、ａ＋ｂ＋ｃ＝１ かつ ０＜ａ＜１、０＜ｂ＜１、０＜ｃ＜１）、Ｌｉ（ＡｌｄＮｉｅＣｏｆ）Ｏ２（但し、ｄ＋ｅ＋ｆ＝１ かつ ０＜ｄ＜１、０＜ｅ＜１、０＜ｆ＜１）、ｘＬｉ２ＭｎＯ３−（１−ｘ）ＬｉＭＯ２（但し、Ｍは、Ｍｎ、Ｎｉ及びＣｏの元素であり、かつ、０＜ｘ＜１）及びＬｉＮｉｇＭｎ（２−ｇ）Ｏ４（但し、０＜ｇ＜２）からなる群から選択される１種のリチウム含有複合酸化物を使用することができる。
本発明のリチウムイオン二次電池用電極材を負極材に用いる場合、前記活物質には、例えばＬｉ４Ｔｉ５Ｏ１２、金属錫を内包した錫酸化物又は金属シリコンを内包したシリコン酸化物を使用することができる。
又は、本発明のリチウムイオン二次電池用電極材を負極材に用いる場合、前記活物質には、金属錫を内包した錫酸化物又は金属シリコンを内包したシリコン酸化物と、黒鉛との混合物を用いてもよい。
An electrode material for a lithium ion secondary battery according to the present invention is an electrode material for a lithium ion secondary battery containing an active material and a conductive material, and the active material is a lithium-containing composite oxide, tin oxide, or silicon oxide The conductive material is amorphous carbon, carbon nanotubes, and carbon black, and a part or all of the surface of the active material is covered with the amorphous carbon.
The coverage of the active material surface with the amorphous carbon can be, for example, 10 to 95%.
The amorphous carbon may be an organic pyrolysis product.
When using a lithium-ion secondary battery electrode material of the present invention in the positive electrode material, as the active material, for example LiCoO 2, LiMn 2 O 4, LiNiO 2, Li (Mn a Ni b Co c) O 2 ( where, a + b + c = 1 and 0 <a <1,0 <b < 1,0 <c <1), Li (Al d Ni e Co f) O 2 ( where, d + e + f = 1 and 0 <d <1,0 <e <1, 0 <f <1), xLi 2 MnO 3 — (1-x) LiMO 2 (where M is an element of Mn, Ni and Co , and 0 <x <1) and LiNi g Mn (2-g) One lithium-containing composite oxide selected from the group consisting of O 4 (where 0 <g <2) can be used.
When the electrode material for a lithium ion secondary battery of the present invention is used as a negative electrode material, the active material includes, for example, Li 4 Ti 5 O 12 , tin oxide containing metal tin or silicon oxide containing metal silicon. Can be used.
Alternatively, when the electrode material for a lithium ion secondary battery of the present invention is used as a negative electrode material, the active material is a mixture of tin oxide containing metal tin or silicon oxide containing metal silicon and graphite. It may be used.

本発明に係るリチウムイオン二次電池用電極材の製造方法は、活物質と、熱分解により非晶質炭素を形成する有機物と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合する工程と、前記混合によって得た混合物を、乾燥した後、更に加熱して前記活物質の表面に前記有機物由来の非晶質炭素を形成する工程と、前記加熱後の混合物を解砕する工程と、を有する。
本発明に係る他のリチウムイオン二次電池用電極材の製造方法は、活物質と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合する工程と、前記混合によって得た混合物を、乾燥した後、更に加熱する工程と、前記加熱後の混合物を解砕する工程と、を有し、前記カーボンナノチューブ及びカーボンブラックのいずれか一方又は両方は非晶質炭素を含有する。A method for producing an electrode material for a lithium ion secondary battery according to the present invention includes a step of mixing an active material, an organic substance that forms amorphous carbon by thermal decomposition, a carbon nanotube, and carbon black in a solvent, After drying the mixture obtained by the mixing, the method further includes heating to form amorphous carbon derived from the organic matter on the surface of the active material, and crushing the mixture after heating. .
Another method for producing an electrode material for a lithium ion secondary battery according to the present invention includes a step of mixing an active material, a carbon nanotube, and carbon black in a solvent, and after drying the mixture obtained by the mixing. And a step of further heating and a step of crushing the mixture after the heating, and either one or both of the carbon nanotubes and carbon black contain amorphous carbon.

本発明に係るリチウムイオン二次電池は、前述したリチウムイオン二次電池用電極材を用いたものである。   The lithium ion secondary battery according to the present invention uses the above-described electrode material for a lithium ion secondary battery.

本発明によれば、大電流充放電を寿命中長きに亘って維持することができ、かつ高容量のリチウムイオン二次電池を実現することができる。   According to the present invention, high-current charge / discharge can be maintained for a long period of time, and a high-capacity lithium ion secondary battery can be realized.

以下、本発明を実施するための形態について、詳細に説明する。なお、本発明は、以下に説明する実施形態に限定されるものではない。   Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

（第１の実施形態）
先ず、本発明の第１の実施形態に係る電極材について説明する。本実施形態の電極材は、リチウムイオン二次電池に用いられるものであり、活物質としてリチウム含有複合酸化物、錫酸化物又はシリコン酸化物を含有すると共に、導電材として非晶質炭素、カーボンナノチューブ及びカーボンブラックを含有する。そして、本実施形態の電極材では、導電材である非晶質炭素により、活物質の表面の一部又は全部が被覆されている。(First embodiment)
First, the electrode material which concerns on the 1st Embodiment of this invention is demonstrated. The electrode material of the present embodiment is used for a lithium ion secondary battery, and contains lithium-containing composite oxide, tin oxide or silicon oxide as an active material, and amorphous carbon or carbon as a conductive material. Contains nanotubes and carbon black. In the electrode material of this embodiment, part or all of the surface of the active material is covered with amorphous carbon that is a conductive material.

これにより、本実施形態の電極材においては、非晶質炭素は活物質の表面を被覆することによって活物質と電気的に接続し、カーボンナノチューブは非晶質炭素及びカーボンブラックの双方と接触することによってこれらを電気的に接続する。更に、カーボンブラックは、電極全体に導電ネットワークを形成し、かつ集電体と電気的に接続する。   Thereby, in the electrode material of the present embodiment, the amorphous carbon is electrically connected to the active material by covering the surface of the active material, and the carbon nanotubes are in contact with both the amorphous carbon and the carbon black. To electrically connect them. Furthermore, carbon black forms a conductive network throughout the electrode and is electrically connected to the current collector.

［非晶質炭素］
導電材である非晶質炭素は、結晶性が低い（黒鉛化度が低い）炭素であり、結晶性が低いことによって活物質の表面を被覆することが可能になる。一方、結晶性が高い（黒鉛化度が高い）炭素は、黒鉛特有の層状構造を有し、その各層はファンデルワールス力により緩く結合しているため、層に垂直な方向に剥離が生じやすい。このため活物質の表面を被覆することには適さない。[Amorphous carbon]
Amorphous carbon, which is a conductive material, is carbon having low crystallinity (low graphitization degree), and the surface of the active material can be covered by low crystallinity. On the other hand, carbon with high crystallinity (high degree of graphitization) has a layered structure peculiar to graphite, and since each layer is loosely bonded by van der Waals force, peeling is likely to occur in a direction perpendicular to the layer. . For this reason, it is not suitable for coating the surface of the active material.

この非晶質炭素による活物質表面の被覆率は、活物質の全表面を１００％とするとき、１０〜９５％であることが好ましく、２０〜９５％であることがさらに好ましい。被覆率が１０％未満の場合、活物質と非晶質炭素との電気的な接続が不充分になる場合がある。なお、被覆率が大きいほど電気的な接続には有利であるため、非晶質炭素による被覆率は１００％でもよいが、充放電時におけるリチウムイオンの活物質への侵入や、活物質からの脱離が阻害される懸念から、非晶質炭素による被覆率は９５％以下とすることが好ましい。   The coverage of the active material surface with amorphous carbon is preferably 10 to 95%, more preferably 20 to 95%, when the entire surface of the active material is 100%. When the coverage is less than 10%, the electrical connection between the active material and the amorphous carbon may be insufficient. Note that the higher the coverage, the more advantageous for electrical connection, so the coverage by amorphous carbon may be 100%. However, penetration of lithium ions into the active material during charging and discharging, In view of the possibility of desorption being inhibited, the coverage with amorphous carbon is preferably 95% or less.

本実施形態の電極材で用いる非晶質炭素は、結晶性が低い（黒鉛化度が低い）こと以外には特に制限はないが、有機物の熱分解物により形成されていることが好ましい。これにより、非晶質炭素による活物質表面の被覆状態を良好にすることができる。熱分解により非晶質炭素を形成する有機物としては、例えばグルコース（Ｃ６Ｈ１２Ｏ６）、ショ糖（Ｃ１２Ｈ２２Ｏ１１）、デキストリン（（Ｃ６Ｈ１２Ｏ５）ｎ）、アスコルビン酸（Ｃ６Ｈ８Ｏ６）、カルボキシメチルセルロース（ＣＭＣ）、ポリビニルピロリドン（ＰＶＰ）、ポリアリルアミン塩酸塩（ＰＡＨ）、ポリアクリル酸塩（ＰＡＡ）、ポリビニルアルコール（ＰＶＡ）、シランカップリング剤及び石炭ピッチなどが挙げられる。The amorphous carbon used in the electrode material of the present embodiment is not particularly limited except that the crystallinity is low (the degree of graphitization is low), but it is preferably formed of a thermal decomposition product of organic matter. Thereby, the covering state of the active material surface by amorphous carbon can be made favorable. Examples of organic substances that form amorphous carbon by pyrolysis include glucose (C 6 H 12 O 6 ), sucrose (C 12 H 22 O 11 ), dextrin ((C 6 H 12 O 5 ) n ), and ascorbine. acid (C 6 H 8 O 6) , carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), poly (allylamine hydrochloride) (PAH), polyacrylate (PAA), polyvinyl alcohol (PVA), a silane coupling agent and coal Pitch and the like.

これらの有機物を用いて活物質表面に非晶質炭素を形成する場合は、例えば活物質と、カーボンナノチューブと、カーボンブラックと、有機物とを溶媒中で混合して得た混合物を、乾燥した後、加熱すればよい。   When amorphous carbon is formed on the active material surface using these organic materials, for example, after drying a mixture obtained by mixing an active material, carbon nanotubes, carbon black, and organic materials in a solvent. What is necessary is just to heat.

また、本発明者は、カーボンナノチューブとカーボンブラックのいずれか一方又は両方が非晶質炭素を含有する場合は、分解して非晶質炭素を形成する有機物を用いなくても、活物質表面を非晶質炭素で良好に被覆できることを見出した。その場合、活物質と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合して得た混合物を、乾燥後さらに加熱すればよい。ここでいう非晶質炭素を含有するカーボンナノチューブ又はカーボンブラックとは、例えば、チューブ本体の表面を被覆する無定形炭素層を有するカーボンナノチューブなどがある（特開２００４−２９９９８６号公報参照）。   Further, the present inventor, when one or both of the carbon nanotube and the carbon black contains amorphous carbon, the active material surface can be obtained without using an organic substance that decomposes to form amorphous carbon. It has been found that it can be satisfactorily coated with amorphous carbon. In that case, a mixture obtained by mixing an active material, carbon nanotubes, and carbon black in a solvent may be further heated after drying. Examples of the carbon nanotubes or carbon black containing amorphous carbon include carbon nanotubes having an amorphous carbon layer covering the surface of the tube body (see Japanese Patent Application Laid-Open No. 2004-299986).

［カーボンナノチューブ］
導電材であるカーボンナノチューブは、繊維径が５〜５０ｎｍであり、かつ、比表面積が５０〜４００ｍ２／ｇであるものが好ましい。本実施形態の電極材においてカーボンナノチューブは、活物質表面を被覆した非晶質炭素と結合することによって電気的に接続する。ここでいう「結合」は、共有結合やファンデルワールス力による結合も含む。[carbon nanotube]
The carbon nanotube which is a conductive material preferably has a fiber diameter of 5 to 50 nm and a specific surface area of 50 to 400 m 2 / g. In the electrode material of this embodiment, the carbon nanotubes are electrically connected by being bonded to the amorphous carbon covering the surface of the active material. “Coupling” here includes covalent bonding and bonding by van der Waals force.

カーボンナノチューブが非晶質炭素と結合する理由は、カーボンナノチューブは繊維状粒子であり、活物質表面を被覆した非晶質炭素層と線接触することが可能なためである。これに対して、カーボンブラックは、球状粒子であるため、非晶質炭素とは点接触しかすることができず、充分な結合は得られない。非晶質炭素とカーボンナノチューブとを結合させる方法は、特に限定されるものではないが、例えば前述した加熱により有機物を分解して活物質表面に非晶質炭素を形成する方法の場合、非晶質炭素を形成する工程において非晶質炭素とカーボンナノチューブの結合も同時に形成される。   The reason why carbon nanotubes are bonded to amorphous carbon is that carbon nanotubes are fibrous particles and can be in line contact with the amorphous carbon layer covering the active material surface. On the other hand, since carbon black is a spherical particle, it can only make point contact with amorphous carbon, and a sufficient bond cannot be obtained. The method for bonding the amorphous carbon and the carbon nanotube is not particularly limited. For example, in the case of the method of decomposing an organic substance by heating to form amorphous carbon on the active material surface, the amorphous carbon is amorphous. In the step of forming the carbonaceous material, a bond between the amorphous carbon and the carbon nanotube is formed at the same time.

また、本実施形態の電極材において、カーボンナノチューブは、カーボンブラックと結合することによって電気的に接続する。カーボンナノチューブとカーボンブラックとを結合させる方法は、特に限定されるものではないが、例えば、炭化水素を熱分解することによりカーボンブラックを製造する際に、カーボンナノチューブを導入し結合させる方法、アセチレンガスの熱分解中及び／又はアセチレンガスを熱分解させた状態で、カーボンナノチューブ形成用触媒を含む炭化水素を供給し、結合させる方法（特表２００９−５０３１８２号公報参照）、カーボンナノチューブとカーボンブラックを炭化水素やアルコールなどの炭素化原料液中に分散させ、炭素化原料液を液状又はガス化した状態で加熱などの操作により炭素化して相互に結合させる方法、カーボンナノチューブ及びカーボンブラックを、固体媒体を用いたメカノケミカル的手法によって結合させる方法などがある。   In the electrode material of this embodiment, the carbon nanotubes are electrically connected by being bonded to carbon black. The method for bonding carbon nanotubes and carbon black is not particularly limited. For example, when carbon black is produced by pyrolyzing hydrocarbons, carbon nanotubes are introduced and bonded, acetylene gas A method of supplying hydrocarbons containing a catalyst for forming carbon nanotubes and bonding them during pyrolysis of acetylene gas and / or in a state in which acetylene gas is thermally decomposed (see JP-T-2009-503182), carbon nanotubes and carbon black A method of dispersing carbonized raw material liquid such as hydrocarbon and alcohol in a liquid or gasified carbonized raw material liquid and gasifying them by an operation such as heating, and bonding carbon nanotubes and carbon black to a solid medium To bond by mechanochemical method And the like.

メカノケミカル的手法により、カーボンナノチューブとカーボンブラックとを結合させる方法としては、ビーズミル、振動ミル及びボールミルなどの媒体撹拌型混合機を用いる方法がある。その場合、例えば活物質と、分解して非晶質炭素を形成する有機物と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合する際、又は活物質と、いずれか一方又は両方が非晶質炭素を含有するカーボンナノチューブと、カーボンブラックとを溶媒中で混合する際に、メカノケミカル的手法を用いてカーボンナノチューブとカーボンブラックを結合させても良いし、混合後の加熱時に結合させてもよい。   As a method for bonding carbon nanotubes and carbon black by a mechanochemical method, there is a method using a medium stirring type mixer such as a bead mill, a vibration mill, or a ball mill. In that case, for example, when the active material, the organic substance that decomposes to form amorphous carbon, the carbon nanotube, and the carbon black are mixed in a solvent, or the active material, either or both are amorphous. When mixing carbon nanotubes containing carbon and carbon black in a solvent, the carbon nanotubes and carbon black may be bonded using a mechanochemical method, or may be bonded during heating after mixing. .

［カーボンブラック］
導電材であるカーボンブラックは、アセチレンブラック又はファーネスブラックであることが好ましく、電池性能に影響を及ぼす可能性がある不純物含有量が比較的少ないアセチレンブラックであることがさらに好ましい。また、カーボンブラックの比表面積は、カーボンナノチューブの比表面積よりも小さく、かつ、１０〜２００ｍ２／ｇであることが好ましい。更に、本実施形態の電極材に用いるカーボンブラックは、ＪＩＳ Ｋ １４６９で規定される灰分が１．０質量％以下であることが好ましい。[Carbon black]
The carbon black as the conductive material is preferably acetylene black or furnace black, and more preferably acetylene black having a relatively small content of impurities that may affect battery performance. Moreover, it is preferable that the specific surface area of carbon black is smaller than the specific surface area of a carbon nanotube, and is 10-200 m < 2 > / g. Furthermore, the carbon black used for the electrode material of the present embodiment preferably has an ash content defined by JIS K 1469 of 1.0% by mass or less.

本実施形態の電極材において、カーボンブラックは、前述したようにカーボンナノチューブと結合して電気的に接続するだけでなく、電極全体に導電ネットワークを形成し、かつ集電体と電気的に接続する。カーボンブラックが電極全体に導電ネットワークを形成できる理由は、カーボンブラックは、カーボンナノチューブとは異なり球状粒子であり、分散性が良好であるため、電極全体に広がって分布しやすいからである。また、カーボンブラックがカーボンナノチューブや集電体と電気的に接続できる理由は、球状の一次粒子が鎖状に連結した独特の高次構造を有しており、球状粒子であるにも関わらず導通がとりやすいためである。   In the electrode material of the present embodiment, the carbon black is not only coupled and electrically connected to the carbon nanotubes as described above, but also forms a conductive network throughout the electrode and is electrically connected to the current collector. . The reason why carbon black can form a conductive network over the entire electrode is that carbon black is a spherical particle unlike carbon nanotubes and has good dispersibility, so that it easily spreads and distributes throughout the electrode. Carbon black can be electrically connected to carbon nanotubes and current collectors because it has a unique higher-order structure in which spherical primary particles are linked in a chain, and it is conductive despite being spherical particles. It is because it is easy to take.

［活物質］
本実施形態の電極材の活物質は、リチウム含有複合酸化物、錫酸化物又はシリコン酸化物である。例えば本実施形態の電極材を正極材として用いる場合は、ＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉＯ２、Ｌｉ（ＭｎａＮｉｂＣｏｃ）Ｏ２（但し、ａ＋ｂ＋ｃ＝１ かつ ０＜ａ＜１、０＜ｂ＜１、０＜ｃ＜１）、Ｌｉ（ＡｌｄＮｉｅＣｏｆ）Ｏ２（但し、ｄ＋ｅ＋ｆ＝１ かつ ０＜ｄ＜１、０＜ｅ＜１、０＜ｆ＜１）、ｘＬｉ２ＭｎＯ３−（１−ｘ）ＬｉＭＯ２（但し、Ｍは、Ｍｎ、Ｎｉ及びＣｏの元素であり、かつ、０＜ｘ＜１）及びＬｉＮｉｇＭｎ（２−ｇ）Ｏ４（但し、０＜ｇ＜２）などの酸化物系の正極活物質を用いることができる。
[Active material]
The active material of the electrode material of this embodiment is a lithium-containing composite oxide, tin oxide, or silicon oxide. For example, when the electrode material of the present embodiment is used as the positive electrode material, LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , Li (Mn a Ni b Co c ) O 2 (where a + b + c = 1 and 0 <a <1, 0 <b <1,0 <c < 1), Li (Al d Ni e Co f) O 2 ( where, d + e + f = 1 and 0 <d <1,0 <e < 1,0 <f <1), xLi 2 MnO 3 — (1-x) LiMO 2 (where M is an element of Mn, Ni and Co , and 0 <x <1) and LiNi g Mn (2-g) O 4 (where An oxide-based positive electrode active material such as 0 <g <2) can be used.

一方、本実施形態の電極材を負極材として用いる場合は、活物質には、Ｌｉ４Ｔｉ５Ｏ１２、金属錫を内包した錫酸化物及び金属シリコンを内包したシリコン酸化物などを用いることができる。また、負極活物質としては、金属スズを内包した錫酸化物又は金属シリコンを内包したシリコン酸化物に、黒鉛を混合したものを用いることもできる。On the other hand, when the electrode material of this embodiment is used as a negative electrode material, Li 4 Ti 5 O 12 , tin oxide containing metal tin, silicon oxide containing metal silicon, or the like may be used as the active material. it can. Further, as the negative electrode active material, a mixture of tin oxide containing metal tin or silicon oxide containing metal silicon and graphite may be used.

なお、ＬｉＦｅＰＯ４（オリビン型リン酸鉄リチウム）、ＬｉＭｎＰＯ４、ＬｉＭｎＸＦｅ（１−Ｘ）ＰＯ４などのリチウム含有リン酸塩は、本質的に、体積あたりの電池容量向上が困難であるため、本実施形態の電極材の活物質には適さない。Since lithium-containing phosphates such as LiFePO 4 (olivine-type lithium iron phosphate), LiMnPO 4 , and LiMnXFe (1-X) PO 4 are essentially difficult to improve battery capacity per volume, It is not suitable for the active material of the electrode material of the embodiment.

［製造方法］
本実施形態の電極材の製造方法は、特に限定されるものではないが、例えば活物質と、熱分解により非晶質炭素を形成する有機物と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合する工程と、混合によって得た混合物を、乾燥した後、更に加熱して活物質の表面に有機物由来の非晶質炭素を形成する工程と、加熱後の混合物を解砕する工程と、を行うことにより製造することができる。この方法で製造する場合、溶媒に溶解し、かつ加熱時に分解して非晶質炭素を形成しやすい有機物を使用することが好ましい。[Production method]
The method for producing the electrode material of the present embodiment is not particularly limited. For example, an active material, an organic material that forms amorphous carbon by thermal decomposition, carbon nanotubes, and carbon black are mixed in a solvent. And a step of drying the mixture obtained by mixing and further heating to form amorphous carbon derived from organic matter on the surface of the active material, and a step of crushing the mixture after heating. Can be manufactured. When manufacturing by this method, it is preferable to use an organic substance that dissolves in a solvent and easily decomposes upon heating to form amorphous carbon.

また、本実施形態の電極材は、カーボンナノチューブ及びカーボンブラックのいずれか一方又は両方に非晶質炭素を含有するものを用いて、活物質と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合する工程と、混合によって得た混合物を、乾燥した後、更に加熱する工程と、加熱後の混合物を解砕する工程と、を行うことによって製造することもできる。   In addition, the electrode material of the present embodiment is a material containing amorphous carbon in one or both of carbon nanotubes and carbon black, and an active material, carbon nanotubes, and carbon black are mixed in a solvent. It can also be produced by performing a step of performing, a step of further heating after drying the mixture obtained by mixing, and a step of crushing the mixture after heating.

前述した各製造方法における混合工程は、らいかい機、万能混合機、ヘンシェルミキサー若しくはリボンブレンダーなどの混合機、又はビーズミル、振動ミル若しくはボールミルなどの媒体撹拌型混合機を用いて行うことができる。また、混合工程で使用する溶媒は、水でもよいが、カーボンナノチューブやカーボンブラックの分散性を向上させるため、水とアルコールの混合溶媒やアルコールなどの非水溶媒が好ましい。   The mixing step in each of the above-described production methods can be performed using a mixer such as a rake machine, a universal mixer, a Henschel mixer, or a ribbon blender, or a medium stirring mixer such as a bead mill, a vibration mill, or a ball mill. The solvent used in the mixing step may be water, but in order to improve the dispersibility of carbon nanotubes and carbon black, a mixed solvent of water and alcohol or a nonaqueous solvent such as alcohol is preferable.

活物質が、金属錫を内包した錫酸化物又は金属シリコンを内包したシリコン酸化物、更にこれらに黒鉛を混合したものである場合は、混合工程の溶媒には、金属錫や金属シリコンの加水分解を防止したり、黒鉛の分散性を向上させるため、アルコールなどの非水溶媒を使用することが好ましい。   When the active material is tin oxide containing metal tin or silicon oxide containing metal silicon, and further mixed with graphite, the solvent used in the mixing step may be hydrolysis of metal tin or metal silicon. It is preferable to use a non-aqueous solvent such as alcohol in order to prevent the problem and improve the dispersibility of graphite.

また、混合工程後には、得られた混合物を乾燥することにより、溶媒を除去する。混合物の乾燥方法は、特に限定されるものではないが、熱分解により非晶質炭素を形成する有機物を用いる場合は、濾過を行うと、有機物が溶媒と共に濾液として除去されてしまわないように注意する必要がある。そこで、混合物の乾燥には、濾過以外に、凍結乾燥、減圧乾燥、真空乾燥又は振動流動乾燥などの方法を適用することもできる。   Moreover, after a mixing process, a solvent is removed by drying the obtained mixture. The method for drying the mixture is not particularly limited. However, when using an organic substance that forms amorphous carbon by thermal decomposition, be careful not to remove the organic substance as a filtrate together with the solvent when filtration is performed. There is a need to. Therefore, for the drying of the mixture, a method such as freeze drying, reduced pressure drying, vacuum drying or vibration fluidized drying can be applied in addition to filtration.

乾燥後、または乾燥に引き続き、混合物を加熱する。熱分解により非晶質炭素を形成する有機物を用いる場合は、加熱によって有機物から非晶質炭素が形成されると共に、この非晶質炭素が活物質の表面を被覆し、更に非晶質炭素とカーボンナノチューブの結合や、カーボンナノチューブとカーボンブラックの結合が形成される。また、非晶質炭素を含有するカーボンナノチューブや非晶質炭素を含有するカーボンブラックを用いる場合は、カーボンナノチューブ及び／又はカーボンブラックに含まれる非晶質炭素が活物質の表面を被覆すると共に、非晶質炭素とカーボンナノチューブの結合や、カーボンナノチューブとカーボンブラックの結合が形成される。   After drying or subsequent to drying, the mixture is heated. When an organic material that forms amorphous carbon by pyrolysis is used, amorphous carbon is formed from the organic material by heating, and the amorphous carbon covers the surface of the active material. Bonds of carbon nanotubes and bonds between carbon nanotubes and carbon black are formed. In addition, when using carbon nanotubes containing amorphous carbon or carbon black containing amorphous carbon, the amorphous carbon contained in the carbon nanotubes and / or carbon black covers the surface of the active material, A bond between amorphous carbon and carbon nanotubes, or a bond between carbon nanotubes and carbon black is formed.

混合物を加熱する際の温度や雰囲気などの条件は、使用する活物質によって異なる。雰囲気は、炭素系材料の酸化を防止するため、不活性雰囲気又は還元雰囲気が好ましい。また、活物質に、ＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉＯ２、Ｌｉ（ＭｎａＮｉｂＣｏｃ）Ｏ２（但し、ａ＋ｂ＋ｃ＝１ かつ ０＜ａ＜１、０＜ｂ＜１、０＜ｃ＜１）、Ｌｉ（ＡｌｄＮｉｅＣｏｆ）Ｏ２（但し、ｄ＋ｅ＋ｆ＝１ かつ ０＜ｄ＜１、０＜ｅ＜１、０＜ｆ＜１）、ｘＬｉ２ＭｎＯ３−（１−ｘ）ＬｉＭＯ２（但し、Ｍは、Ｍｎ、Ｎｉ及びＣｏの元素であり、かつ、０＜ｘ＜１）及びＬｉＮｉｇＭｎ（２−ｇ）Ｏ４（但し、０＜ｇ＜２）などの酸化物系の正極活物質を用いる場合は、活物質自体の還元分解を防ぐため、乾燥空気などの酸化雰囲気とすることが好ましい。更に、熱分解により非晶質炭素を形成する有機物を使用する場合は、これらの有機物が燃焼せずに分解するように、比較的低温の２００〜４００℃で加熱することが好ましい。
Conditions such as temperature and atmosphere when heating the mixture vary depending on the active material used. The atmosphere is preferably an inert atmosphere or a reducing atmosphere in order to prevent oxidation of the carbon-based material. In addition, LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , Li (Mna a Ni b Co c ) O 2 (where a + b + c = 1 and 0 <a <1, 0 <b <1, 0 <c <1), Li (Al d Ni e Co f) O 2 ( where, d + e + f = 1 and 0 <d <1,0 <e < 1,0 <f <1), xLi 2 MnO 3 - (1-x ) LiMO 2 (where M is an element of Mn, Ni and Co , and 0 <x <1) and oxidation of LiNi g Mn (2-g) O 4 (where 0 <g <2) When a physical positive electrode active material is used, an oxidizing atmosphere such as dry air is preferably used to prevent reductive decomposition of the active material itself. Furthermore, when using the organic substance which forms amorphous carbon by thermal decomposition, it is preferable to heat at 200-400 degreeC of comparatively low temperature so that these organic substances may decompose | disassemble without burning.

一方、負極活物質であるＬｉ４Ｔｉ５Ｏ１２を用いる場合は、Ｌｉ４Ｔｉ５Ｏ１２は分解しにくいため、少し高めの３００〜５００℃で加熱することが好ましい。また、活物質に、金属錫を内包した錫酸化物又はこれに黒鉛を混合したものを用いる場合は、不活性雰囲気又は還元雰囲気中でも活物質は分解しないため、アルゴンや窒素などの不活性ガスが使用可能であるが、金属錫の融点は２３２℃と低温であるため、２３２℃よりも低い温度で加熱することが好ましい。On the other hand, in the case of using the Li 4 Ti 5 O 12 as the negative electrode active material, since the Li 4 Ti 5 O 12 is hardly decomposed, it is preferable to heat at 300 to 500 ° C. slightly higher. In addition, in the case where a tin oxide containing metal tin or a mixture thereof with graphite is used as the active material, since the active material is not decomposed even in an inert atmosphere or a reducing atmosphere, an inert gas such as argon or nitrogen is present. Although it can be used, since the melting point of metallic tin is as low as 232 ° C., it is preferable to heat at a temperature lower than 232 ° C.

活物質が、金属シリコンを内包したシリコン酸化物又はこれに黒鉛を混合したものの場合も、不活性雰囲気又は還元雰囲気中でも活物質は分解せず、しかもシリコンの融点は１４１０℃と高温であるため、１４００℃付近までの広い温度範囲で加熱が可能であり、更にアルゴンや窒素などの不活性ガスが使用可能である。加熱後の混合物は、解砕により凝集を解かれ、本実施形態の電極材が得られる。   Even when the active material is silicon oxide containing metal silicon or a mixture of graphite with this, the active material is not decomposed even in an inert atmosphere or a reducing atmosphere, and the melting point of silicon is as high as 1410 ° C. Heating is possible over a wide temperature range up to around 1400 ° C., and an inert gas such as argon or nitrogen can be used. The mixture after heating is deagglomerated by crushing, and the electrode material of this embodiment is obtained.

本実施形態の電極材は、電極内の電子伝導ネットワークが向上し、しかも活物質、導電剤及び金属箔の集電体間における電子の授受が円滑に行われるため、従来の各電極材料を単純に混合して製造した電極材に比べて、電極抵抗が低減され、大電流充放電が可能になる。また、本実施形態の電極材は、活物質、導電剤及び金属箔の集電体間の電気的な接続が最適化されており、少量の導電剤で導通をとることができるため、特に少量使用の場合に従来の電極材との性能差が顕著になる。また少量使用が可能な分、電池容量の向上に寄与するところが大きい。   The electrode material of the present embodiment improves the electron conduction network in the electrode and facilitates the transfer of electrons between the active material, the conductive agent and the current collector of the metal foil. Compared with the electrode material manufactured by mixing the electrode, the electrode resistance is reduced, and large current charging / discharging becomes possible. In addition, the electrode material of the present embodiment has an optimized electrical connection among the active material, the conductive agent, and the current collector of the metal foil, and can conduct electricity with a small amount of the conductive agent. When used, the performance difference from the conventional electrode material becomes significant. In addition, the amount that can be used in a small amount greatly contributes to the improvement of battery capacity.

これにより、本実施形態の電極材を使用することにより、電極材中の活物質の割合を高めて、リチウムイオン二次電池を高容量化することが可能になる。   Thereby, by using the electrode material of this embodiment, it becomes possible to increase the ratio of the active material in the electrode material and to increase the capacity of the lithium ion secondary battery.

（第２の実施形態）
次に、本発明の第２の実施形態に係るリチウムイオン二次電池について説明する。本実施形態のリチウムイオン二次電池は、前述した正極材及び／又は負極材に、前述した第１の実施形態の電極材を用いたものである。(Second Embodiment)
Next, a lithium ion secondary battery according to a second embodiment of the present invention will be described. The lithium ion secondary battery of the present embodiment uses the electrode material of the first embodiment described above for the positive electrode material and / or the negative electrode material described above.

一般的なリチウムイオン二次電池は、負極と正極とからなる電極がセパレータを介して積層又は捲回されることにより形成される電極群と、この電極群が浸漬される電解液とで構成されている。電極はリチウムイオン二次電池用電極材を有機バインダー等を介して金属箔の集電体に塗工することにより形成される。   A typical lithium ion secondary battery is composed of an electrode group formed by laminating or winding an electrode composed of a negative electrode and a positive electrode via a separator, and an electrolyte solution in which the electrode group is immersed. ing. The electrode is formed by applying an electrode material for a lithium ion secondary battery to a current collector of a metal foil through an organic binder or the like.

前述した第１の実施形態の電極材を用いて、リチウムイオン二次電池の電極を形成する場合、電極材を溶媒やバインダーと混練して、電極合剤（スラリー）を形成する。例えば正極を形成する場合は、溶媒としてＮ−メチルピロリドン（ＮＭＰ）を使用し、バインダーとしてポリフッ化ビニリデン（ＰＶＤＦ）を使用することができる。また、負極を形成する場合は、溶媒として水を使用し、バインダーとしてカルボキシメチルセルロース（ＣＭＣ）及びスチレンブタジエンゴム（ＳＢＲ）が用いられることが多い。   When forming the electrode of a lithium ion secondary battery using the electrode material of the first embodiment described above, the electrode material is kneaded with a solvent or a binder to form an electrode mixture (slurry). For example, when forming a positive electrode, N-methylpyrrolidone (NMP) can be used as a solvent, and polyvinylidene fluoride (PVDF) can be used as a binder. When forming the negative electrode, water is often used as a solvent, and carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) are often used as binders.

そして、電極合剤を、金属箔の集電体に塗工した後、加圧成形することにより電極を作製することができる。活物質が、ＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉＯ２、Ｌｉ（ＭｎａＮｉｂＣｏｃ）Ｏ２（但し、ａ＋ｂ＋ｃ＝１ かつ ０＜ａ＜１、０＜ｂ＜１、０＜ｃ＜１）、Ｌｉ（ＡｌｄＮｉｅＣｏｆ）Ｏ２（但し、ｄ＋ｅ＋ｆ＝１ かつ ０＜ｄ＜１、０＜ｅ＜１、０＜ｆ＜１）、ｘＬｉ２ＭｎＯ３−（１−ｘ）ＬｉＭＯ２（但し、Ｍは、Ｍｎ、Ｎｉ及びＣｏの元素であり、かつ、０＜ｘ＜１）及びＬｉＮｉｇＭｎ（２−ｇ）Ｏ４（但し、０＜ｇ＜２）などの酸化物系の正極活物質、又は負極活物質であるＬｉ４Ｔｉ５Ｏ１２である場合は、集電体はアルミニウム箔が用いられる。また、活物質が、金属錫を内包した錫酸化物又は金属シリコンを内包したシリコン酸化物又はこれらに黒鉛を混合したものである場合は、銅箔が用いられる。
And after coating an electrode mixture on the collector of metal foil, an electrode can be produced by press-molding. Active material, LiCoO 2, LiMn 2 O 4 , LiNiO 2, Li (Mn a Ni b Co c) O 2 ( where, a + b + c = 1 and 0 <a <1,0 <b < 1,0 <c <1 ), Li (Al d Ni e Co f) O 2 ( where, d + e + f = 1 and 0 <d <1,0 <e < 1,0 <f <1), xLi 2 MnO 3 - (1-x) LiMO 2 (where M is an element of Mn, Ni and Co , and 0 <x <1) and an oxide system such as LiNi g Mn (2-g) O 4 (where 0 <g <2) In the case of Li 4 Ti 5 O 12 which is a positive electrode active material or a negative electrode active material, an aluminum foil is used as the current collector. Further, when the active material is tin oxide containing metal tin, silicon oxide containing metal silicon, or a mixture of these with graphite, copper foil is used.

リチウムイオン二次電池に使用される他の材料としては、セパレータや電解液などが挙げられる。セパレータは、正極及び負極を電気的に絶縁して電解液を保持するものであり、ポリエチレンやポリプロピレンなどの合成樹脂製のものやセルロース製不織布を使用することができる。電解液の保持性を向上させるために、セパレータは、多孔性フィルム状のものを用いることが好ましい。   Other materials used for the lithium ion secondary battery include a separator and an electrolytic solution. A separator electrically insulates a positive electrode and a negative electrode, and hold | maintains electrolyte solution, The thing made from synthetic resins, such as polyethylene and a polypropylene, and the nonwoven fabric made from a cellulose can be used. In order to improve the retention of the electrolytic solution, the separator is preferably a porous film.

また、前述した電極群が浸漬される電解液としては、リチウム塩を含む非水電解液又はイオン伝導ポリマーなどを用いることが好ましい。リチウム塩を含む非水電解液における非水電解質の非水溶媒としては、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ジエチルカーボネート（ＤＥＣ）、ジメチルカーボネート（ＤＭＣ）、メチルエチルカーボネート（ＭＥＣ）などが挙げられる。また、非水溶媒に溶解できるリチウム塩としては、六フッ化リン酸リチウム（ＬｉＰＦ６）、ホウ四フッ化リチウム（ＬｉＢＦ４）、トリフルオロメタンスルホン酸リチウム（ＬｉＳＯ３ＣＦ４）などが挙げられる。In addition, as the electrolytic solution in which the electrode group described above is immersed, it is preferable to use a nonaqueous electrolytic solution containing lithium salt or an ion conductive polymer. Examples of the nonaqueous solvent for the nonaqueous electrolyte in the nonaqueous electrolyte containing a lithium salt include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). Is mentioned. Examples of lithium salts that can be dissolved in a non-aqueous solvent include lithium hexafluorophosphate (LiPF 6 ), lithium borotetrafluoride (LiBF 4 ), and lithium trifluoromethanesulfonate (LiSO 3 CF 4 ).

本実施形態のリチウムイオン二次電池は、前述した第１の実施形態の電極材を用いているため、大電流充放電を寿命中長きに亘って維持することができ、かつ高容量である。   Since the lithium ion secondary battery according to the present embodiment uses the electrode material according to the first embodiment described above, large current charge / discharge can be maintained over a long period of time, and the capacity is high.

以下、本発明の実施例及び比較例を挙げて、本発明の効果について具体的に説明する。本実施例においては、以下に示す方法で電極材を作製し、その性能を評価した。   Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention. In this example, an electrode material was produced by the method shown below, and its performance was evaluated.

＜実施例１〜８＞
混合機を用いて、下記表１に示す活物質、有機物、カーボンナノチューブ及びカーボンブラックなどを、溶媒中で混合した。その後、乾燥、加熱、解砕することによって実施例１〜８の電極材を得た。下記表２に各工程における条件を示す。<Examples 1-8>
Using a mixer, active materials, organic substances, carbon nanotubes, carbon black and the like shown in Table 1 below were mixed in a solvent. Then, the electrode material of Examples 1-8 was obtained by drying, heating, and crushing. Table 2 below shows the conditions in each step.

＜実施例９＞
硝酸マンガン（Ｍｎ（ＮＯ３）２・６Ｈ２Ｏ）、硝酸ニッケル（Ｎｉ（ＮＯ３）２・６Ｈ２Ｏ）及び硝酸コバルト（Ｃｏ（ＮＯ３）２・６Ｈ２Ｏ）を、蒸留水に、モル比で、Ｍｎ：Ｎｉ：Ｃｏ＝４：１：１の割合になるよう添加し、溶解させた。その後、窒素雰囲気中で炭酸リチウム（Ｌｉ２ＣＯ３）を、モル比で、Ｌｉ２ＣＯ３：（Ｍｎ＋Ｎｉ＋Ｃｏ）＝１．７５：１の割合になるように添加して充分に撹拌後、濾過、洗浄、乾燥して粉末を得た。<Example 9>
Manganese nitrate (Mn (NO 3 ) 2 .6H 2 O), nickel nitrate (Ni (NO 3 ) 2 .6H 2 O) and cobalt nitrate (Co (NO 3 ) 2 .6H 2 O) are added to distilled water. It was added and dissolved in a molar ratio of Mn: Ni: Co = 4: 1: 1. Thereafter, lithium carbonate (Li 2 CO 3 ) was added in a nitrogen atmosphere at a molar ratio of Li 2 CO 3 : (Mn + Ni + Co) = 1.75: 1, and after sufficient stirring, filtered, The powder was obtained by washing and drying.

これを、大気中、５００℃で４時間焼成した後、９００℃で１０時間焼成して、黒色粉末を得た。得られた粉末について、元素分析及びＸ線回折測定を行ったところ、０．５Ｌｉ２ＭｎＯ３−０．５ＬｉＭｎ１／３Ｎｉ１／３Ｃｏ１／３Ｏ２の組成を有する化合物であった。This was baked at 500 ° C. for 4 hours in the air, and then baked at 900 ° C. for 10 hours to obtain a black powder. When the obtained powder was subjected to elemental analysis and X-ray diffraction measurement, it was a compound having a composition of 0.5Li 2 MnO 3 —0.5LiMn 1/3 Ni 1/3 Co 1/3 O 2 .

次いで、特開２００４−２９９９８６号公報の実施例１に記載の方法によって、表面が無定形炭素層で被覆されたカーボンナノチューブを得た。これと、前述した黒色粉末及びカーボンブラックを、溶媒中で混合機を用いて混合した。その後、乾燥、加熱、解砕することによって、実施例９の電極材を得た。使用した各材料を下記表１に示す。また、下記表２に各工程における条件を示す。   Subsequently, the carbon nanotube by which the surface was coat | covered with the amorphous carbon layer was obtained by the method as described in Example 1 of Unexamined-Japanese-Patent No. 2004-299986. This was mixed with the black powder and carbon black described above in a solvent using a mixer. Then, the electrode material of Example 9 was obtained by drying, heating, and crushing. The materials used are shown in Table 1 below. Table 2 below shows the conditions in each step.

＜実施例１０＞
塩化ニッケル（ＮｉＣｌ２・６Ｈ２Ｏ）及び塩化マンガン（ＭｎＣｌ２・４Ｈ２Ｏ）を、モル比で、Ｎｉ：Ｍｎ＝１：３になるように混合した後、シュウ酸アンモニウム（（ＮＨ４）２Ｃ２Ｏ４・Ｈ２Ｏ）を、モル比で、（Ｎｉ＋Ｍｎ）：Ｃ２Ｏ４＝５：６になるように加えて混合した。混合物を、１１０℃で２時間乾燥した後、大気中、４００℃で４時間焼成した。<Example 10>
After mixing nickel chloride (NiCl 2 · 6H 2 O) and manganese chloride (MnCl 2 · 4H 2 O) in a molar ratio of Ni: Mn = 1: 3, ammonium oxalate ((NH 4 ) 2 C 2 O 4 .H 2 O) was added and mixed so that the molar ratio was (Ni + Mn): C 2 O 4 = 5: 6. The mixture was dried at 110 ° C. for 2 hours and then calcined in the atmosphere at 400 ° C. for 4 hours.

その後、炭酸リチウム（Ｌｉ２ＣＯ３）を、モル比で、Ｌｉ：（Ｎｉ＋Ｍｎ）＝１：２になるように加えて混合し、更に、大気中、７００℃で４８時間焼成して黒色粉末を得た。得られた粉末について、元素分析及びＸ線回折測定を行ったところ、ＬｉＮｉ０．５Ｍｎ１．５Ｏ４の組成を有する化合物であった。Thereafter, lithium carbonate (Li 2 CO 3 ) is added and mixed so that the molar ratio is Li: (Ni + Mn) = 1: 2, and further calcined at 700 ° C. for 48 hours in the air to obtain a black powder. Obtained. The obtained powder was subjected to elemental analysis and X-ray diffraction measurement. As a result, it was a compound having a composition of LiNi 0.5 Mn 1.5 O 4 .

次いで、特開２００４−２９９９８６号公報の実施例１に記載の方法によって表面が無定形炭素層で被覆されたカーボンナノチューブを得た。これと、前述した黒色粉末及びカーボンブラックを、溶媒中で混合機を用いて混合した。その後、乾燥、加熱、解砕することによって、実施例１０の電極材を得た。使用した各材料を下記表１に、各工程における条件を下記表２にそれぞれ示す。   Subsequently, the carbon nanotube by which the surface was coat | covered with the amorphous carbon layer was obtained by the method as described in Example 1 of Unexamined-Japanese-Patent No. 2004-299986. This was mixed with the black powder and carbon black described above in a solvent using a mixer. Then, the electrode material of Example 10 was obtained by drying, heating, and crushing. The materials used are shown in Table 1 below, and the conditions in each step are shown in Table 2 below.

Figure 0006344740
Figure 0006344740

Figure 0006344740
Figure 0006344740

前述した方法で製造した実施例１〜１０の電極材について、走査型電子顕微鏡（日本電子株式会社製 ＪＳＭ−７４００Ｆ）を用いて反射電子組成像を撮影し、活物質に対する非晶質炭素の被覆率を測定した。また、透過型電子顕微鏡（日本電子株式会社製 ＪＥＭ−２０１０）を用いて、実施例１〜１０の電極材の透過電子線（ＴＥＭ）像を撮影し、非晶質炭素とカーボンナノチューブとの結合の有無及びカーボンナノチューブとカーボンブラックの結合の有無を確認した。その結果を、下記表３に示す。   About the electrode material of Examples 1-10 manufactured by the method mentioned above, a reflection electron composition image was image | photographed using the scanning electron microscope (JEOL Co., Ltd. JSM-7400F), and the coating of the amorphous carbon with respect to an active material The rate was measured. Moreover, the transmission electron beam (TEM) image of the electrode material of Examples 1-10 was image | photographed using the transmission electron microscope (JEOL Co., Ltd. JEM-2010), and the coupling | bonding of an amorphous carbon and a carbon nanotube The presence / absence of carbon nanotubes and carbon black / carbon black were confirmed. The results are shown in Table 3 below.

Figure 0006344740
Figure 0006344740

上記表３に示すように、実施例１〜１０の電極材は、非晶質炭素被覆率が１０％以上であった。また、実施例１〜１０の電極材は、いずれも、非晶質炭素とカーボンナノチューブの結合、カーボンナノチューブとカーボンブラックの結合、及びカーボンブラックによる導電ネットワークの形成が確認された。   As shown in Table 3 above, the electrode materials of Examples 1 to 10 had an amorphous carbon coverage of 10% or more. Moreover, as for the electrode material of Examples 1-10, formation of the conductive network by the coupling | bonding of an amorphous carbon and a carbon nanotube, the coupling | bonding of a carbon nanotube and carbon black, and carbon black was confirmed.

＜実施例１１〜２０＞
次に、実施例１〜１０の電極材を使用して電極（正極・負極）を形成し、実施例１１〜２０のリチウムイオン二次電池を作製した。具体的には、実施例１〜１０の電極材と、バインダーとしてポリフッ化ビニリデン（株式会社クレハ製 ＫＦポリマー溶液）を、質量比で、９５：５の割合で配合した。これに分散溶媒としてＮ−メチルピロリドン（シグマアルドリッチ社製 品番３２８６３４）を添加し、混練機（プライミクス社製 ハイビスミックス及びホモディスパー）を用いて混練して電極合剤（スラリー）を作製した。<Examples 11 to 20>
Next, electrodes (positive electrode / negative electrode) were formed using the electrode materials of Examples 1 to 10, and lithium ion secondary batteries of Examples 11 to 20 were produced. Specifically, the electrode materials of Examples 1 to 10 and polyvinylidene fluoride (Kureha Co., Ltd. KF polymer solution) as a binder were blended at a mass ratio of 95: 5. N-methylpyrrolidone (product number 328634 manufactured by Sigma-Aldrich) was added thereto as a dispersion solvent, and kneaded using a kneader (Hibismix and homodisper manufactured by Primix) to prepare an electrode mixture (slurry).

この電極合剤（スラリー）を、厚さ２０μｍのアルミニウム箔又は銅箔に塗布、乾燥し、その後、プレス、４０ｍｍ角に裁断して、リチウム二次電池用電極を得た。これらを電気的に隔離するセパレータには、５０ｍｍ角のオレフィン繊維製不織布を用いた。電解液にはＥＣ（Ａｌｄｒｉｃｈ社製 エチレンカーボネート）と、ＭＥＣ（Ａｌｄｒｉｃｈ社製 メチルエチルカーボネート）とを、体積比で、３０：７０の割合で混合した溶液中に、六フッ化リン酸リチウム（ステラケミファ社製 ＬｉＰＦ６）を１ｍｏｌ／Ｌ 溶解したものを用いた。This electrode mixture (slurry) was applied to an aluminum foil or copper foil having a thickness of 20 μm, dried, and then cut into a 40 mm square by pressing to obtain an electrode for a lithium secondary battery. A 50 mm square olefin fiber nonwoven fabric was used as a separator for electrically isolating these. As the electrolyte, lithium hexafluorophosphate (stellar) was added to a solution in which EC (ethylene carbonate manufactured by Aldrich) and MEC (methyl ethyl carbonate manufactured by Aldrich) were mixed at a volume ratio of 30:70. A solution obtained by dissolving 1 mol / L of LiPF 6 manufactured by Chemifa Corporation was used.

一部の正極用電極材に対しては、負極活物質に黒鉛（大阪ガス株式会社製 人造黒鉛 ＭＣＭＢ６−２８）を用い、導電材としてアセチレンブラック（電気化学工業株式会社製 ＨＳ−１００）及びバインダーとしてポリフッ化ビニリデンを、質量比で、９５：１：４の割合で混合した。その後、前述した電極材と同様にスラリーを作製し、厚さ２０μｍの銅箔に塗布、乾燥した後、プレス、４０ｍｍ角に裁断した負極電極を用いた。正極と負極に端子を接続した後、全体をアルミラミネート製パッケージに封入して７０ｍｍ角ラミネート型電池とした。   For some positive electrode materials, graphite (artificial graphite MCMB6-28 manufactured by Osaka Gas Co., Ltd.) is used as the negative electrode active material, and acetylene black (HS-100 manufactured by Denki Kagaku Kogyo Co., Ltd.) and a binder are used as the conductive material. Polyvinylidene fluoride was mixed at a mass ratio of 95: 1: 4. Thereafter, a slurry was prepared in the same manner as the electrode material described above, applied to a copper foil having a thickness of 20 μm, dried, then pressed, and a negative electrode cut into a 40 mm square was used. After connecting the terminals to the positive electrode and the negative electrode, the whole was enclosed in an aluminum laminate package to make a 70 mm square laminate type battery.

なお、アルミニウム箔又は銅箔に塗布、乾燥し、その後、プレスした電極の一部は電池に用いずに電極表面を走査型電子顕微鏡を用いて観察し、得られた走査電子線（ＳＥＭ）像によって、カーボンブラックが電極全体に導電ネットワークを形成していることを確認した。これら結果は上記表３に示す。実施例１〜１０いずれの電極表面においてもカーボンブラックによる導電ネットワークの形成が確認されたため、集電体である金属箔と接している電極裏面にも同様の導電ネットワークが形成されて集電体と電気的に接続しているものと推定された。
In addition, the scanning electron beam (SEM) image obtained by observing the surface of the electrode with a scanning electron microscope without using a part of the pressed electrode applied to an aluminum foil or copper foil and then using the battery for a battery. Thus, it was confirmed that carbon black formed a conductive network throughout the electrode. These results are shown in Table 3 above. Since formation of the conductive network by carbon black was confirmed on any electrode surface of Examples 1 to 10, a similar conductive network was formed on the back surface of the electrode in contact with the metal foil as the current collector, and the current collector and Presumed to be electrically connected.

＜比較例１〜１０＞
前述した実施例１〜１０と同じ活物質、カーボンナノチューブ及びカーボンブラックを使用し、下記表４に示す比較例１〜１０の電極材を作製した。比較例１〜１０の電極材は、そのままバインダであるポリフッ化ビニリデン（株式会社クレハ製 ＫＦポリマー溶液）に、質量比で、バインダー：残部＝５：９５の割合となるように配合し、これに分散溶媒としてＮ−メチルピロリドンを添加し、混練機を用いて混練して電極合剤（スラリー）を作製した。<Comparative Examples 1-10>
Using the same active material, carbon nanotube, and carbon black as in Examples 1 to 10 described above, electrode materials of Comparative Examples 1 to 10 shown in Table 4 below were produced. The electrode materials of Comparative Examples 1 to 10 are blended into the polyvinylidene fluoride (Kureha Co., Ltd. KF polymer solution) as a binder as it is in a mass ratio such that the ratio of binder: remaining part = 5: 95. N-methylpyrrolidone was added as a dispersion solvent and kneaded using a kneader to prepare an electrode mixture (slurry).

但し、比較例１〜８においては、分解して非晶質炭素を形成する有機物を添加せず、代わりに実施例１〜８において使用した有機物が分解した際に生成する炭素量と同量のカーボンブラックを、実施例１〜８のカーボンブラック量に対して増量して添加した。比較例１〜１０の電極材における活物質、カーボンナノチューブ及びカーボンブラックの種類及び配合量を下記表４にまとめて示す。   However, in Comparative Examples 1-8, the organic substance which decomposes | disassembles and forms amorphous carbon is not added, but the amount of carbon produced | generated when the organic substance used in Examples 1-8 decomposes instead is decomposed | disassembled. Carbon black was added in an increased amount relative to the amount of carbon black in Examples 1-8. The types and blending amounts of the active material, carbon nanotube, and carbon black in the electrode materials of Comparative Examples 1 to 10 are summarized in Table 4 below.

Figure 0006344740
Figure 0006344740

＜実施例２１〜２２＞
実施例１におけるショ糖の量を３ｇから０．３ｇに変更した以外は実施例１と同様にして実施例２１の電極材を作製した。具体的には、導電剤、熱分解により非晶質炭素を形成する有機物、カーボンナノチューブ及びカーボンブラックを、溶媒中で混合機を用いて混合した後、乾燥、加熱、解砕することによって実施例２１の電極材を得た。
< Examples 21 to 22 >
The electrode material of Example 21 was produced in the same manner as in Example 1 except that the amount of sucrose in Example 1 was changed from 3 g to 0.3 g. Specifically, a conductive agent, organic substances by pyrolysis to form amorphous carbon, carbon nanotubes and carbon black, were mixed using a mixer in a solvent, exemplary drying, heating, by crushing Example 21 electrode materials were obtained.

得られた実施例２１の電極材の活物質に対する非晶質炭素の被覆率を、走査型電子顕微鏡を用いて得た反射電子組成像によって測定したところ、５％であった。また、透過型電子顕微鏡（日本電子株式会社製 ＪＥＭ−２０１０）を用いて得た透過電子線（ＴＥＭ）像によって、非晶質炭素とカーボンナノチューブとの結合の有無及びカーボンナノチューブとカーボンブラックの結合の有無を確認したところ、カーボンナノチューブとカーボンブラックの結合は認められたものの非晶質炭素とカーボンナノチューブの結合は認められなかった。
The coverage of the amorphous carbon with respect to the active material of the obtained electrode material of Example 21 was measured by a reflection electron composition image obtained using a scanning electron microscope and found to be 5%. In addition, the transmission electron beam (TEM) image obtained using a transmission electron microscope (JEM-2010, manufactured by JEOL Ltd.) indicates the presence or absence of bonding between amorphous carbon and carbon nanotubes and the bonding between carbon nanotubes and carbon black. When the presence or absence of this was confirmed, the bond between the carbon nanotube and the carbon black was recognized, but the bond between the amorphous carbon and the carbon nanotube was not recognized.

次に、実施例２１の電極材を、実施例１０と同様にバインダーとしてのポリフッ化ビニリデンを配合し、分散溶媒としてＮ−メチルピロリドンを添加し、混練機を用いて混練して電極合剤（スラリー）を作製した。さらにこれを電極に用いて、実施例２２のラミネート型電池を作製した。
Next, the electrode material of Example 21 was blended with polyvinylidene fluoride as a binder in the same manner as in Example 10, N-methylpyrrolidone was added as a dispersion solvent, and the mixture was kneaded using a kneader to prepare an electrode mixture ( Slurry). Further, using this as an electrode, a laminate type battery of Example 22 was produced.

＜比較例１３〜２２＞
比較例１〜１０で作製した電極合剤を電極に用いた以外は、それぞれ実施例１１〜２０と全く同様にして比較例１３〜２２のラミネート型電池を作製した。<Comparative Examples 13-22>
Laminated batteries of Comparative Examples 13 to 22 were produced in exactly the same manner as Examples 11 to 20 except that the electrode mixture produced in Comparative Examples 1 to 10 was used for the electrodes.

［放電性能評価］
次に、前述した方法で作製した実施例１１〜２０、２２及び比較例１３〜２２のリチウムイオン二次電池（ラミネート型電池）について放電性能試験を行った。具体的には、各電池を初回充電後、充放電効率が１００％近傍になることを確認し、０．７ｍＡ／ｃｍ２の電流密度にて定電流放電を２．７Ｖ（実施例１２、１５、１７及び比較例１４、１７、１９は１．２Ｖ、実施例２０及び比較例２２は３．０Ｖ）まで行った際の放電容量を測定した。この容量（ｍＡｈ）を１時間で充放電可能な電流値を「１Ｃ」とした。
[Discharge performance evaluation]
Then, discharge was performed performance tests for Example manufactured by the method described above 11 to 20, 22 and Comparative Examples 13 to 22 of the lithium ion secondary battery (a laminated cell). Specifically, after each battery was charged for the first time, it was confirmed that the charge / discharge efficiency was close to 100%, and constant current discharge was performed at 2.7 V at a current density of 0.7 mA / cm 2 (Examples 12 and 15 , 17 and Comparative Examples 14, 17, and 19 were measured at 1.2 V, and Example 20 and Comparative Example 22 were measured at 3.0 V). The current value at which this capacity (mAh) can be charged and discharged in 1 hour was defined as “1C”.

初回充放電後、充電は４．３Ｖ（実施例１２、１５、１７及び比較例１４、１７、１９は２．８Ｖ、実施例１９及び比較例２１は４．８Ｖ、実施例２０及び比較例２２は５．０Ｖ）（０．２Ｃ定電流、０．０５Ｃ電流時終了）、放電はサイクル毎に、０．２Ｃ、０．３３Ｃ、０．５Ｃ、１Ｃ、３Ｃ、５Ｃ、１０Ｃ（定電流、２．７Ｖ時終了、実施例１２、１５、１７及び比較例１４、１７、１９は１．２Ｖ時終了、実施例２０及び比較例２２は３．０Ｖ時終了）と徐々に電流値を増加させて、休止はそれぞれの間に１０分間行って充放電を行い、初回（０．２Ｃ）の充放電容量に対する充放電容量の比（％）をレート特性とした。さらに、ＳＯＣ（充電深度）５０％時におけるＩ−Ｖ特性より、電池の直流抵抗（ＤＣＲ）を算出した。充電時における直流抵抗を「充電ＤＣＲ」、放電時を「放電ＤＣＲ」とした。これらの結果を、下記表５にまとめて示す。   After the first charge / discharge, the charge was 4.3 V (Examples 12, 15, 17 and Comparative Examples 14, 17, 19 were 2.8 V, Example 19 and Comparative Example 21 were 4.8 V, Example 20 and Comparative Example 22) Is 5.0V) (finished at 0.2C constant current, 0.05C current), and discharge is 0.2C, 0.33C, 0.5C, 1C, 3C, 5C, 10C (constant current, 2C) for each cycle. 7V end, Examples 12, 15, 17 and Comparative Examples 14, 17 and 19 end at 1.2V, Example 20 and Comparative Example 22 end at 3.0V) and gradually increase the current value. In addition, charging and discharging were performed for 10 minutes between each period, and the ratio (%) of the charging / discharging capacity to the initial (0.2 C) charging / discharging capacity was defined as a rate characteristic. Further, the direct current resistance (DCR) of the battery was calculated from the IV characteristics at an SOC (depth of charge) of 50%. The direct current resistance during charging was defined as “charging DCR”, and the discharging resistance was defined as “discharge DCR”. These results are summarized in Table 5 below.

Figure 0006344740
Figure 0006344740

上記表５に示すように、実施例１〜１０の電極材を使用した実施例１１〜２０のリチウムイオン二次電池は、比較例１２〜２２のリチウム二次電池に比べて、セル容量が大きく、また、充電及び放電における直流抵抗も低く、放電性能も優れていた。この結果から、本発明によれば、大電流充放電を寿命中長きに亘って維持することができ、かつ高容量のリチウムイオン二次電池を実現可能であることが確認された。   As shown in Table 5 above, the lithium ion secondary batteries of Examples 11 to 20 using the electrode materials of Examples 1 to 10 have a larger cell capacity than the lithium secondary batteries of Comparative Examples 12 to 22. Moreover, the direct current resistance in charging and discharging was low, and the discharging performance was excellent. From this result, according to the present invention, it was confirmed that large current charge / discharge can be maintained for a long period of time and a high capacity lithium ion secondary battery can be realized.

Claims (5)

活物質及び導電材を含有するリチウムイオン二次電池用電極材であって、
前記活物質はリチウム含有複合酸化物、錫酸化物又はシリコン酸化物であり、
前記導電材は、非晶質炭素、カーボンナノチューブ及びカーボンブラックであり、
前記非晶質炭素により前記活物質の表面が、１０〜９５％の被覆率で被覆されており、
活物質と、カーボンナノチューブと、カーボンブラックとを溶媒中で混合する工程と、
前記混合によって得た混合物を、乾燥した後、更に加熱する工程と、
前記加熱後の混合物を解砕する工程と、
を有する製造方法で製造され、
前記カーボンナノチューブ及びカーボンブラックのいずれか一方又は両方は非晶質炭素を含有する、
リチウムイオン二次電池用電極材。 An electrode material for a lithium ion secondary battery containing an active material and a conductive material,
The active material is a lithium-containing composite oxide, tin oxide or silicon oxide,
The conductive material is amorphous carbon, carbon nanotube and carbon black,
The surface of the active material is coated with the amorphous carbon at a coverage of 10 to 95%,
Mixing an active material, carbon nanotubes, and carbon black in a solvent;
A step of further heating after drying the mixture obtained by the mixing;
Crushing the mixture after heating;
Produced by a production method having
Either or both of the carbon nanotubes and carbon black contain amorphous carbon.
Electrode material for lithium ion secondary batteries. 前記非晶質炭素は有機物の熱分解物である請求項１に記載のリチウムイオン二次電池用電極材。 The electrode material for a lithium ion secondary battery according to claim 1 , wherein the amorphous carbon is an organic pyrolysis product. 前記活物質は、Ｌｉ４Ｔｉ５Ｏ１２、金属錫を内包した錫酸化物又は金属シリコンを内包したシリコン酸化物であり、
負極材に用いられる請求項１又は２に記載のリチウムイオン二次電池用電極材。 The active material is Li 4 Ti 5 O 12 , tin oxide containing metal tin or silicon oxide containing metal silicon,
The electrode material for lithium ion secondary batteries according to claim 1 or 2 , which is used for a negative electrode material. 前記活物質は、金属錫を内包した錫酸化物又は金属シリコンを内包したシリコン酸化物と、黒鉛との混合物であり、
負極材に用いられる請求項１〜３のいずれか１項に記載のリチウムイオン二次電池用電極材。 The active material is a mixture of tin oxide encapsulating metal tin or silicon oxide encapsulating metal silicon and graphite,
The electrode material for lithium ion secondary batteries according to any one of claims 1 to 3 , which is used for a negative electrode material. 請求項１〜４のいずれか１項に記載の電極材を用いたリチウムイオン二次電池。 The lithium ion secondary battery using the electrode material of any one of Claims 1-4 .
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