JP2006012576A - Electrode for nonaqueous electrolyte secondary battery and its manufacturing method - Google Patents

Electrode for nonaqueous electrolyte secondary battery and its manufacturing method Download PDF

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JP2006012576A
JP2006012576A JP2004187398A JP2004187398A JP2006012576A JP 2006012576 A JP2006012576 A JP 2006012576A JP 2004187398 A JP2004187398 A JP 2004187398A JP 2004187398 A JP2004187398 A JP 2004187398A JP 2006012576 A JP2006012576 A JP 2006012576A
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electrode
secondary battery
electrolyte secondary
negative electrode
nonaqueous electrolyte
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Satoru Miyawaki
悟 宮脇
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Shin Etsu Chemical Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for a nonaqueous electrolyte secondary battery obtaining a lithium ion secondary battery with high recyclability, and also to provide its manufacturing method. <P>SOLUTION: This electrode for the nonaqueous electrolyte secondary battery comprises a positive electrode or a negative electrode formed by applying an electrode mixture containing an active material, a binder, and, if necessary, a conductive agent on a current collector in a sheet, and fine convexo-concave is formed on the surface of the electrode. By using the electrode for the nonaqueous electrolyte secondary battery of this invention, the lithium ion secondary battery having high capacity and excellent recyclability can be obtained. By the manufacturing method of this invention, the electrode for the nonaqueous electrolyte secondary battery is easily manufactured, and industrial scale production is met. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、よりサイクル性の高いリチウムイオン二次電池が得られる非水電解質二次電池用電極及びその作製方法に関するものである。   The present invention relates to an electrode for a non-aqueous electrolyte secondary battery from which a lithium ion secondary battery with higher cycleability can be obtained, and a method for producing the same.

近年、携帯型の電子機器、通信機器等の著しい発展に伴い、経済性と機器の小型化、軽量化の観点から、高エネルギー密度の二次電池が強く要望されている。従来、この種の二次電池の高容量化策として、例えば、負極材料にＶ，Ｓｉ，Ｂ，Ｚｒ，Ｓｎなどの酸化物及びそれらの複合酸化物を用いる方法（特開平５−１７４８１８号、特開平６−６０８６７号公報：特許文献１，２他）、溶融急冷した金属酸化物を負極材として適用する方法（特開平１０−２９４１１２号公報：特許文献３）、負極材料に酸化珪素を用いる方法（特許第２９９７７４１号公報：特許文献４）、負極材料にＳｉ2Ｎ2Ｏ及びＧｅ2Ｎ2Ｏを用いる方法（特開平１１−１０２７０５号公報：特許文献５）等が知られている。また、負極材に導電性を付与する目的として、ＳｉＯを黒鉛とメカニカルアロイング後、炭化処理する方法（特開２０００−２４３３９６号公報：特許文献６）、Ｓｉ粒子表面に化学蒸着法により炭素層を被覆する方法（特開２０００−２１５８８７号公報：特許文献７）、酸化珪素粒子表面に化学蒸着法により炭素層を被覆する方法（特開２００２−４２８０６号公報：特許文献８）、更には、ポリイミド系バインダーを用いて成膜後焼結する負極の製造方法（特開２００４−２２４３３号公報：特許文献９）がある。 In recent years, with the remarkable development of portable electronic devices, communication devices, etc., secondary batteries with high energy density are strongly demanded from the viewpoints of economy and downsizing and weight reduction of devices. Conventionally, as a measure for increasing the capacity of this type of secondary battery, for example, a method of using an oxide such as V, Si, B, Zr, Sn, or a composite oxide thereof as a negative electrode material (Japanese Patent Laid-Open No. 5-174818, Japanese Patent Laid-Open No. 6-60867: Patent Documents 1 and 2), a method of applying a melted and quenched metal oxide as a negative electrode material (Japanese Patent Laid-Open No. 10-294112: Patent Document 3), and silicon oxide as a negative electrode material A method (Japanese Patent No. 2997441: Patent Document 4), a method using Si 2 N 2 O and Ge 2 N 2 O as a negative electrode material (Japanese Patent Laid-Open No. 11-102705: Patent Document 5), and the like are known. In addition, for the purpose of imparting conductivity to the negative electrode material, a method of carbonizing SiO with graphite and then carbonizing (Japanese Patent Laid-Open No. 2000-243396: Patent Document 6), a carbon layer formed on the Si particle surface by chemical vapor deposition (Japanese Patent Laid-Open No. 2000-215887: Patent Document 7), a method of coating the surface of silicon oxide particles with a carbon layer by chemical vapor deposition (Japanese Patent Laid-Open No. 2002-42806: Patent Document 8), There is a method for producing a negative electrode using a polyimide binder and sintering after film formation (Japanese Patent Laid-Open No. 2004-22433: Patent Document 9).

しかしながら、上記従来の方法では、充放電容量が上がり、エネルギー密度が高くなるものの、サイクル性が不十分であったり、充放電に伴う負極膜そのものの容積変化が大きく、また集電体からの剥離などの問題があり、市場の要求特性には未だ不十分であったりし、必ずしも満足でき得るものではなかった。このような背景より、サイクル性が高くかつエネルギー密度の高い電極の作製方法が望まれていた。   However, in the above conventional method, although the charge / discharge capacity is increased and the energy density is increased, the cycleability is insufficient, the volume change of the negative electrode film itself due to charge / discharge is large, and peeling from the current collector is performed. However, the required characteristics of the market are still insufficient and cannot always be satisfied. From such a background, a method for manufacturing an electrode having high cycleability and high energy density has been desired.

特に、特許第２９９７７４１号公報（特許文献４）では、酸化珪素をリチウムイオン二次電池負極材として用い、高容量の電極を得ているが、本発明者らがみる限りにおいては、未だ初回充放電時における不可逆容量が大きかったり、サイクル性が実用レベルに達していなかったりし、改良する余地がある。また、負極材に導電性を付与した技術についても、特開２０００−２４３３９６号公報（特許文献６）では、固体と固体の融着であるため、均一な炭素皮膜が形成されず、導電性が不十分であるといった問題があるし、特開２０００−２１５８８７号公報（特許文献７）の方法においては、均一な炭素皮膜の形成が可能となるものの、Ｓｉを負極材として用いているため、リチウムイオンの吸脱着時の膨張・収縮があまりにも大きすぎて、結果として実用に耐えられず、サイクル性が低下するためにこれを防止するべく充電量の制限を設けなくてはならず、特開２００２−４２８０６号公報（特許文献８）の方法においては、微細な珪素結晶の析出、炭素被覆の構造及び基材との融合が不十分であることより、サイクル性の向上は確認されるも、充放電のサイクル数を重ねると徐々に容量が低下し、一定回数後に急激に低下するという現象があり、二次電池用としてはまだ不十分であるといった問題があった。   In particular, in Japanese Patent No. 2997741 (Patent Document 4), silicon oxide is used as a negative electrode material for a lithium ion secondary battery to obtain a high-capacity electrode. There is room for improvement because the irreversible capacity at the time of discharge is large and the cycle performance has not reached the practical level. In addition, regarding the technique for imparting conductivity to the negative electrode material, in Japanese Patent Application Laid-Open No. 2000-243396 (Patent Document 6), since it is a solid-solid fusion, a uniform carbon film is not formed, and conductivity is improved. There is a problem that it is insufficient, and in the method of Japanese Patent Application Laid-Open No. 2000-215887 (Patent Document 7), although a uniform carbon film can be formed, since Si is used as a negative electrode material, lithium The expansion / contraction at the time of adsorption / desorption of ions is too large, and as a result, it cannot withstand practical use. In the method of 2002-42806 (patent document 8), the precipitation of fine silicon crystals, the structure of the carbon coating, and the fusion with the base material are insufficient, and thus the improvement in cycleability is confirmed. , Gradually decreased capacity Hover the number of cycles of charge and discharge, there is a phenomenon that decreases rapidly after a certain number of times, there is a problem as the secondary battery is still insufficient.

特開平５−１７４８１８号公報JP-A-5-174818 特開平６−６０８６７号公報JP-A-6-60867 特開平１０−２９４１１２号公報JP 10-294112 A 特許第２９９７７４１号公報Japanese Patent No. 2999741 特開平１１−１０２７０５号公報JP-A-11-102705 特開２０００−２４３３９６号公報JP 2000-243396 A 特開２０００−２１５８８７号公報JP 2000-215887 A 特開２００２−４２８０６号公報JP 2002-42806 A 特開２００４−２２４３３号公報Japanese Patent Laid-Open No. 2004-22433

本発明は、上記事情に鑑みなされたもので、よりサイクル性の高いリチウムイオン二次電池が得られる非水電解質二次電池用電極、及びその作製方法を提供することを目的とする。   This invention is made | formed in view of the said situation, and it aims at providing the electrode for nonaqueous electrolyte secondary batteries from which a lithium ion secondary battery with higher cycle property is obtained, and its manufacturing method.

本発明者は、上記目的を達成するため鋭意検討した結果、リチウムイオン二次電池に用いられる非水電解質二次電池用電極の表面に微細な凹凸を形成することにより、よりサイクル性の高いリチウムイオン二次電池が得られることを見出し、本発明をなすに至った。   As a result of intensive studies to achieve the above object, the present inventor has found that lithium having higher cycleability can be obtained by forming fine irregularities on the surface of a non-aqueous electrolyte secondary battery electrode used in a lithium ion secondary battery. The inventors have found that an ion secondary battery can be obtained, and have made the present invention.

従って、本発明は、
〔１〕集電体に活物質、結着剤及び必要により導電剤を含む電極合剤を塗布してシート状に形成した正極又は負極からなる非水電解質二次電池用電極において、該電極の表面に微細な凹凸を形成してなることを特徴とする非水電解質二次電池用電極、
〔２〕集電体に活物質、結着剤及び必要により導電剤を含む電極合剤を塗布してシート状の正極又は負極からなる非水電解質二次電池用電極を製造する方法において、集電体に電極合剤をシート状に塗布すると共に、このシート状電極合剤表面に微細な凹凸を形成することを特徴とする非水電解質二次電池用電極の作製方法
を提供する。 Therefore, the present invention
[1] An electrode for a nonaqueous electrolyte secondary battery comprising a positive electrode or a negative electrode formed into a sheet by applying an electrode mixture containing an active material, a binder and, if necessary, a conductive agent to a current collector. An electrode for a non-aqueous electrolyte secondary battery, characterized by forming fine irregularities on the surface;
[2] In a method for producing a nonaqueous electrolyte secondary battery electrode comprising a sheet-like positive electrode or negative electrode by applying an electrode mixture containing an active material, a binder, and optionally a conductive agent to a current collector, Provided is a method for producing an electrode for a non-aqueous electrolyte secondary battery, in which an electrode mixture is applied in a sheet form to an electric body, and fine irregularities are formed on the surface of the sheet electrode mixture.

この場合、電極は負極であって、その負極活物質がリチウムイオンを吸蔵、放出し得る材料、特に珪素、珪素と二酸化珪素の複合分散体、一般式ＳｉＯx（１．０≦ｘ＜１．６）で表される酸化珪素、もしくはこれらの混合物、又はこれらの表面処理物であることが好ましい。また、電極表面の算術平均粗さＲａは、０．５μｍ以上が望ましいが、電極表面に微細な凹凸を形成する手段としては、シート状電極合剤表面に粗化処理された金属箔を張り合わせてプレスすることにより、この金属箔の粗化面を転写する方法、或いは機械的粗化処理法が好適である。 In this case, the electrode is a negative electrode, and a material in which the negative electrode active material can occlude and release lithium ions, particularly silicon, a composite dispersion of silicon and silicon dioxide, a general formula SiO x (1.0 ≦ x <1. The silicon oxide represented by 6), a mixture thereof, or a surface treatment product thereof is preferable. The arithmetic average roughness Ra of the electrode surface is preferably 0.5 μm or more, but as a means for forming fine irregularities on the electrode surface, a roughened metal foil is laminated on the surface of the sheet electrode mixture. A method of transferring the roughened surface of the metal foil by pressing or a mechanical roughening method is preferable.

本発明の非水電解質二次電池用電極を用いることにより、高容量でかつサイクル性に優れたリチウムイオン二次電池を得ることができる。また、本発明の作製方法によれば、非水電解質二次電池用電極を簡便に製造することができ、工業的規模の生産にも十分耐え得るものである。   By using the electrode for a nonaqueous electrolyte secondary battery of the present invention, a lithium ion secondary battery having a high capacity and excellent cycleability can be obtained. Moreover, according to the production method of the present invention, the electrode for a non-aqueous electrolyte secondary battery can be easily produced and can sufficiently withstand industrial scale production.

本発明の非水電解質二次電池用電極は、集電体に活物質、結着剤及び必要により導電剤を含む電極合剤を塗布してシート状に形成した正極又は負極からなり、該電極（正極又は負極）表面に微細な凹凸を形成してなるものである。   The electrode for a non-aqueous electrolyte secondary battery of the present invention comprises a positive electrode or a negative electrode formed into a sheet shape by applying an electrode mixture containing an active material, a binder and, if necessary, a conductive agent to a current collector. (Positive electrode or negative electrode) The surface is formed with fine irregularities.

本発明における非水電解質二次電池用電極は、その表面に微細な凹凸を持たせることにより、活物質の膨張収縮による電極の崩壊を緩和してサイクル性を高めたものである。即ち、膨張収縮の緩和のため、電極の成形密度を落とした場合は、活物質への集電性が低下し、活物質本来の容量を取り出せないばかりではなく、集電性の低下からサイクル特性が著しく低下してしまう。そこで、活物質への集電性を損なうことなく膨張収縮による電極の崩壊を緩和するため、活物質の成形密度は大きくし、電極の表面に微細な凹凸を持たせることにより、活物質への集電性の低下を防ぎ、膨張収縮による電極の崩壊が緩和され、優れたサイクル特性を示すことが可能となるものである。   The electrode for a non-aqueous electrolyte secondary battery according to the present invention is provided with fine irregularities on its surface, thereby reducing the collapse of the electrode due to the expansion and contraction of the active material and improving the cycle performance. In other words, if the electrode molding density is lowered to reduce expansion and contraction, the current collection performance to the active material is reduced, and the original capacity of the active material cannot be taken out. Will drop significantly. Therefore, in order to alleviate the collapse of the electrode due to expansion and contraction without impairing the current collecting property to the active material, the molding density of the active material is increased, and the surface of the electrode is provided with fine irregularities so that It is possible to prevent a decrease in current collecting property, alleviate the collapse of the electrode due to expansion and contraction, and exhibit excellent cycle characteristics.

ここで、本発明の非水電解質二次電池用電極、特に負極を形成するリチウムイオン二次電池負極材について具体的に例示すると、負極材に使用される負極活物質としては、リチウムイオンを吸蔵、放出し得る材料を用いることができる。リチウムイオンを吸蔵、放出し得る材料としては、金属珪素（Ｓｉ）、金属珪素（Ｓｉ）と二酸化珪素（ＳｉＯ2）等の珪素系化合物との複合分散体、一般式ＳｉＯx（１．０≦ｘ＜１．６）で示される珪素低級酸化物（いわゆる酸化珪素）等の珪素系物質の他に、下記式
ＭＯa
（式中、ＭはＧｅ，Ｓｎ，Ｐｂ，Ｂｉ，Ｓｂ，Ｚｎ，Ｉｎ，Ｍｇから選ばれる少なくとも１種であり、ａ＝０．１〜４の正数である。）
で表される珪素を含まない金属酸化物、もしくは、下記式
ＬｉＭbＯc
（式中、ＭはＧｅ，Ｓｎ，Ｐｂ，Ｂｉ，Ｓｂ，Ｚｎ，Ｉｎ，Ｍｇ，Ｓｉから選ばれる少なくとも１種であり、ｂ＝０．１〜４の正数、ｃ＝０．１〜８の正数である。）
で表される（珪素を含んだものであってもよい）リチウム複合酸化物であり、具体的には、ＧｅＯ，ＧｅＯ2，ＳｎＯ，ＳｎＯ2，Ｓｎ2Ｏ3，Ｂｉ2Ｏ3，Ｂｉ2Ｏ5，Ｓｂ2Ｏ3，Ｓｂ2Ｏ4，Ｓｂ2Ｏ5，ＺｎＯ，Ｉｎ2Ｏ，ＩｎＯ，Ｉｎ2Ｏ3，ＭｇＯ，Ｌｉ2ＳｉＯ3，Ｌｉ4ＳｉＯ4，Ｌｉ2Ｓｉ3Ｏ7，Ｌｉ2Ｓｉ2Ｏ5，Ｌｉ8ＳｉＯ6，Ｌｉ6Ｓｉ2Ｏ7，Ｌｉ4Ｇｅ9Ｏ7，Ｌｉ4Ｇｅ9Ｏ2，Ｌｉ5Ｇｅ8Ｏ19，Ｌｉ4Ｇｅ5Ｏ12，Ｌｉ5Ｇｅ2Ｏ7，Ｌｉ4ＧｅＯ4，Ｌｉ2Ｇｅ7Ｏ15，Ｌｉ2ＧｅＯ3，Ｌｉ2Ｇｅ4Ｏ9，Ｌｉ2ＳｎＯ3，Ｌｉ8ＳｎＯ6，Ｌｉ2ＰｂＯ3，Ｌｉ7ＳｂＯ5，ＬｉＳｂＯ3，Ｌｉ3ＳｂＯ4，Ｌｉ3ＢｉＯ5，Ｌｉ6ＢｉＯ6，ＬｉＢｉＯ2，Ｌｉ4Ｂｉ6Ｏ11，Ｌｉ6ＺｎＯ4，Ｌｉ4ＺｎＯ3，Ｌｉ2ＺｎＯ2，ＬｉＩｎＯ2，Ｌｉ3ＩｎＯ3、又はこれらの非量論的化合物等が挙げられるが、特に理論充放電容量の大きな珪素系物質を用いた場合に本発明がより効果的である。 Here, the electrode for the non-aqueous electrolyte secondary battery of the present invention, particularly the lithium ion secondary battery negative electrode material forming the negative electrode, will be specifically exemplified. As the negative electrode active material used for the negative electrode material, lithium ions are occluded. Any material that can be released can be used. Examples of materials that can occlude and release lithium ions include metal silicon (Si), a composite dispersion of metal silicon (Si) and a silicon compound such as silicon dioxide (SiO 2 ), and a general formula SiO x (1.0 ≦ 1.0 In addition to silicon-based materials such as silicon lower oxide (so-called silicon oxide) represented by x <1.6), the following formula MO a
(In the formula, M is at least one selected from Ge, Sn, Pb, Bi, Sb, Zn, In, and Mg, and a is a positive number of 0.1 to 4.)
Or a metal oxide containing no silicon represented by the following formula: LiM b O c
(In the formula, M is at least one selected from Ge, Sn, Pb, Bi, Sb, Zn, In, Mg, Si, b = 0.1-4 positive number, c = 0.1-8) Is a positive number.)
Lithium composite oxide (which may contain silicon), specifically, GeO, GeO 2 , SnO, SnO 2 , Sn 2 O 3 , Bi 2 O 3 , Bi 2 O 5 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , ZnO, In 2 O, InO, In 2 O 3 , MgO, Li 2 SiO 3 , Li 4 SiO 4 , Li 2 Si 3 O 7 , Li 2 Si 2 O 5 , Li 8 SiO 6 , Li 6 Si 2 O 7 , Li 4 Ge 9 O 7 , Li 4 Ge 9 O 2 , Li 5 Ge 8 O 19 , Li 4 Ge 5 O 12 , Li 5 Ge 2 O 7 , Li 4 GeO 4 , Li 2 Ge 7 O 15 , Li 2 GeO 3 , Li 2 Ge 4 O 9 , Li 2 SnO 3 , Li 8 SnO 6 , Li 2 PbO 3 , Li 7 SbO 5 , LiSbO 3 , Li 3 SbO 4, Li 3 BiO 5, Li 6 BiO 6, LiBiO 2, Li 4 Bi 6 O 11, Li 6 Zn Examples include O 4 , Li 4 ZnO 3 , Li 2 ZnO 2 , LiInO 2 , Li 3 InO 3 , or non-stoichiometric compounds thereof, but particularly when a silicon-based material having a large theoretical charge / discharge capacity is used. The present invention is more effective.

この場合、Ｓｉ、ＳｉＯ2及び一般式ＳｉＯx（１．０≦ｘ＜１．６）で表される酸化珪素の物性については特に限定されるものではないが、平均粒子径は０．０１〜５０μｍ、特に０．１〜１０μｍが好ましい。なお、Ｓｉ（金属珪素）は、例えば平均粒子径１〜５００ｎｍ、好ましくは２〜２００ｎｍ程度の微結晶が結晶性又は非晶質のＳｉＯ2（二酸化珪素）等の珪素系化合物中に分散した構造の平均粒子径０．０１〜５０μｍ、特に０．１〜１０μｍ程度の複合分散体の形態であってもよい。平均粒子径が０．０１μｍより小さいと表面酸化の影響で純度が低下し、リチウムイオン二次電池負極材として用いた場合、充放電容量が低下したり、嵩密度が低下し、単位体積当りの充放電容量が低下する場合がある。５０μｍより大きいと、例えば後述する化学蒸着処理における黒鉛析出量が減少し、結果としてリチウムイオン二次電池負極材として用いた場合にサイクル性能が低下するおそれがある。 In this case, the physical properties of silicon oxide represented by Si, SiO 2 and general formula SiO x (1.0 ≦ x <1.6) are not particularly limited, but the average particle diameter is 0.01 to 50 micrometers, especially 0.1-10 micrometers are preferable. Si (metal silicon) has a structure in which, for example, fine crystals having an average particle diameter of 1 to 500 nm, preferably about 2 to 200 nm are dispersed in a silicon-based compound such as crystalline or amorphous SiO 2 (silicon dioxide). The average particle size may be in the form of a composite dispersion having an average particle diameter of 0.01 to 50 μm, particularly about 0.1 to 10 μm. If the average particle size is smaller than 0.01 μm, the purity decreases due to the effect of surface oxidation, and when used as a negative electrode material for a lithium ion secondary battery, the charge / discharge capacity decreases or the bulk density decreases. The charge / discharge capacity may be reduced. When it is larger than 50 μm, for example, the amount of graphite deposited in the chemical vapor deposition process described later decreases, and as a result, when used as a negative electrode material for a lithium ion secondary battery, cycle performance may be deteriorated.

なお、平均粒子径は、レーザー光回折法による粒度分布測定における累積重量平均値（Ｄ50）又はメジアン径で表すことができる。 The average particle diameter can be represented by the cumulative weight average value (D 50) or median diameter in particle size distribution measurement by laser diffraction method.

また、本発明においては、上記リチウムイオンを吸蔵、放出し得る材料を有機珪素系表面処理剤で処理して負極活物質材料とすることもできる。   In the present invention, the material capable of inserting and extracting lithium ions may be treated with an organosilicon surface treatment agent to form a negative electrode active material.

ここで、リチウムイオンを吸蔵、放出し得る材料を処理する有機珪素系表面処理剤の種類は特に限定されるものではないが、一般的にシランカップリング剤、その（部分）加水分解縮合物、シリル化剤、シリコーンレジンから選ばれる１種又は２種以上が用いられる。なお、（部分）加水分解縮合物とは、シランカップリング剤の部分加水分解縮合物でも全部を加水分解縮合したシランカップリング剤の加水分解縮合物でもよいことを意味する。   Here, the type of the organosilicon surface treatment agent for treating a material capable of inserting and extracting lithium ions is not particularly limited, but is generally a silane coupling agent, its (partial) hydrolysis condensate, One or more selected from silylating agents and silicone resins are used. In addition, the (partial) hydrolysis condensate means that it may be a partial hydrolysis condensate of a silane coupling agent or a hydrolysis condensate of a silane coupling agent obtained by hydrolytic condensation.

更に、本発明においては、負極活物質として、上記リチウムイオンを吸蔵、放出し得る材料を含む負極活物質材料の表面を導電性皮膜で被覆したものを用いることができる。この導電性皮膜は、構成された電池において、分解や変質を起こさない導電材料であればよく、具体的にはＡｌ，Ｔｉ，Ｆｅ，Ｎｉ，Ｃｕ，Ｚｎ，Ａｇ，Ｓｎ等の金属膜や炭素皮膜が挙げられる。これらの中でも炭素皮膜が被覆処理のし易さ、導電率の高さからより好適に用いられる。   Furthermore, in the present invention, a negative electrode active material in which the surface of a negative electrode active material containing a material capable of occluding and releasing lithium ions is coated with a conductive film can be used. The conductive film may be any conductive material that does not cause decomposition or alteration in the constructed battery. Specifically, the conductive film is a metal film such as Al, Ti, Fe, Ni, Cu, Zn, Ag, Sn, or carbon. A film is mentioned. Among these, a carbon film is more preferably used from the viewpoint of easy coating treatment and high electrical conductivity.

この場合、導電性皮膜を形成する方法は特に限定されず、めっき法、メカニカルアロイング法、化学蒸着法等が挙げられるが、導電性皮膜の均一形成に優れる点で化学蒸着法がより好適に用いられる。   In this case, the method for forming the conductive film is not particularly limited, and examples thereof include a plating method, a mechanical alloying method, and a chemical vapor deposition method, but the chemical vapor deposition method is more preferable in terms of excellent uniform formation of the conductive film. Used.

また、導電性被覆処理を施す母材（即ち、被覆処理前の負極活物質材料）は、リチウムイオンを吸蔵、放出し得る材料を含む負極活物質材料単独でもよいが、更に導電性を高めるために導電材料（例えば黒鉛粉末）と、リチウムイオンを吸蔵、放出し得る材料を含む負極活物質材料との混合物を用いることもできる。なお、上記混合物を用いる場合、導電材料の混合割合としては、混合物全量の１〜６０質量％、特に１０〜５０質量％、とりわけ２０〜５０質量％とすることが好ましい。   Further, the base material to be subjected to the conductive coating treatment (that is, the negative electrode active material prior to the coating treatment) may be a negative electrode active material alone containing a material capable of occluding and releasing lithium ions. Alternatively, a mixture of a conductive material (for example, graphite powder) and a negative electrode active material containing a material capable of inserting and extracting lithium ions can be used. In addition, when using the said mixture, it is preferable to set it as 1-60 mass% of a mixture whole quantity, especially 10-50 mass%, especially 20-50 mass% as a mixture ratio of an electrically-conductive material.

上記母材に導電性皮膜を形成する方法としては、上記母材（リチウムイオンを吸蔵、放出し得る材料を含む負極活物質材料単独或いはこれと前記導電材料との混合物）の表面を少なくとも有機物ガス又は蒸気を含む雰囲気下、５００〜１４００℃、より好ましくは７００〜１３００℃の温度域で熱処理することにより導電性皮膜を形成する方法が好適に採用される。熱処理温度が５００℃より低いと、例えば導電性炭素皮膜が形成されない場合があったり、長時間の熱処理が必要となったりし、効率的ではない。逆に１４００℃より高いと、化学蒸着処理時に粒子同士が融着、凝集を起こす可能性があり、凝集面で導電性皮膜が形成されず、リチウムイオン二次電池負極材として用いた場合、サイクル性能が低下するおそれがある。特に珪素を母材として用いた場合には、珪素の融点に近い温度となるため、珪素が溶融し、粒子表面に導電性皮膜を被覆処理することが困難となるおそれがある。   As a method of forming a conductive film on the base material, the surface of the base material (a negative electrode active material material alone or a mixture of the above and the conductive material containing a material capable of inserting and extracting lithium ions) is at least an organic gas. Alternatively, a method of forming a conductive film by heat treatment in a temperature range of 500 to 1400 ° C., more preferably 700 to 1300 ° C. in an atmosphere containing steam is suitably employed. When the heat treatment temperature is lower than 500 ° C., for example, a conductive carbon film may not be formed or a long-time heat treatment may be required, which is not efficient. On the other hand, when the temperature is higher than 1400 ° C., particles may be fused and aggregated during chemical vapor deposition, and a conductive film is not formed on the agglomerated surface, and when used as a negative electrode material for a lithium ion secondary battery, Performance may be reduced. In particular, when silicon is used as a base material, the temperature is close to the melting point of silicon, so that silicon melts and it may be difficult to coat the surface of the particles with a conductive film.

本発明における有機物ガスを発生する原料として用いられる有機物としては、特に非酸性雰囲気下において、上記熱処理温度で熱分解して炭素（黒鉛）を生成し得るものが好適に選択され、例えば、メタン、エタン、エチレン、アセチレン、プロパン、ブタン、ブテン、ペンタン、イソブタン、ヘキサン等の炭化水素の単独もしくは混合物、ベンゼン、トルエン、キシレン、スチレン、エチルベンゼン、ジフェニルメタン、ナフタレン、フェノール、クレゾール、ニトロベンゼン、クロルベンゼン、インデン、クマロン、ピリジン、アントラセン、フェナントレン等の１環乃至３環の芳香族炭化水素もしくはこれらの混合物が挙げられる。また、タール蒸留工程で得られるガス軽油、クレオソート油、アントラセン油、ナフサ分解タール油も単独もしくは混合物として用いることができる。   As an organic substance used as a raw material for generating an organic gas in the present invention, a substance that can be pyrolyzed at the above heat treatment temperature to generate carbon (graphite), particularly in a non-acidic atmosphere, is preferably selected. A single or mixture of hydrocarbons such as ethane, ethylene, acetylene, propane, butane, butene, pentane, isobutane, hexane, benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, naphthalene, phenol, cresol, nitrobenzene, chlorobenzene, indene , Monocyclic to tricyclic aromatic hydrocarbons such as coumarone, pyridine, anthracene and phenanthrene, or a mixture thereof. Further, gas light oil, creosote oil, anthracene oil, and naphtha cracked tar oil obtained in the tar distillation step can be used alone or as a mixture.

これら負極活物質材料と有機物ガスとの熱処理は特に限定されず、非酸化性雰囲気において、加熱機構を有する反応装置を用いればよく、連続法、回分法での処理が可能で、具体的には流動層反応炉、回転炉、竪型移動層反応炉、トンネル炉、バッチ炉等をその目的に応じ適宜選択することができる。   The heat treatment of the negative electrode active material and the organic gas is not particularly limited, and a reactor having a heating mechanism may be used in a non-oxidizing atmosphere, and can be processed by a continuous method or a batch method. A fluidized bed reaction furnace, a rotary furnace, a vertical moving bed reaction furnace, a tunnel furnace, a batch furnace, or the like can be appropriately selected according to the purpose.

本発明の導電性皮膜量は、被覆処理後の母材（即ち、前記したリチウムイオンを吸蔵、放出し得る材料を含む負極活物質材料単独を被覆したもの或いはこれと前記導電材料との混合物からなる負極活物質材料全体を被覆したもの）の５〜７０質量％、特に１０〜５０質量％が好ましい。導電性皮膜量が５質量％未満では、導電性向上に著しい効果は見られず、リチウムイオン二次電池負極材として用いた場合にサイクル性が十分でない場合があり、逆に７０質量％を超えると、炭素の割合が多くなりすぎ、リチウムイオン二次電池負極材として用いた場合に負極容量が低下するおそれがある。   The amount of the conductive film of the present invention is determined from the base material after the coating process (that is, a material coated with the negative electrode active material alone containing a material capable of occluding and releasing lithium ions, or a mixture of this and the conductive material). 5 to 70% by mass, particularly 10 to 50% by mass of the whole of the negative electrode active material material to be coated). When the amount of the conductive film is less than 5% by mass, no significant effect is seen in improving the conductivity, and when used as a negative electrode material for a lithium ion secondary battery, the cycle performance may not be sufficient, and conversely, it exceeds 70% by mass. And the ratio of carbon becomes too large, and when used as a negative electrode material for a lithium ion secondary battery, the negative electrode capacity may decrease.

また、リチウムイオン二次電池負極材を用いて負極を作製する場合、上記被覆処理後の導電性負極活物質に、更に黒鉛等の導電剤を添加することができる。この場合においても導電剤の種類は特に限定されず、構成された電池において、分解や変質を起こさない電子伝導性の材料であればよく、具体的にはＡｌ，Ｔｉ，Ｆｅ，Ｎｉ，Ｃｕ，Ｚｎ，Ａｇ，Ｓｎ，Ｓｉ等の金属粉末や金属繊維、又は天然黒鉛、人造黒鉛、各種のコークス粉末、メソフェーズ炭素、気相成長炭素繊維、ピッチ系炭素繊維、ＰＡＮ系炭素繊維、各種の樹脂焼成体等の黒鉛などを用いることができる。
上記導電剤を添加する場合、導電剤の添加量としては、被覆処理後の混合物全体に対して１〜６０質量％、特に１０〜５０質量％、とりわけ２０〜５０質量％とすることが好ましい。添加量が少なすぎると膨張・収縮に耐えられず、サイクル性が低下する場合があり、多すぎると充放電容量が小さくなる場合がある。 Moreover, when producing a negative electrode using a lithium ion secondary battery negative electrode material, a conductive agent such as graphite can be further added to the conductive negative electrode active material after the coating treatment. Also in this case, the kind of the conductive agent is not particularly limited, and any electronic conductive material that does not cause decomposition or alteration in the constituted battery may be used. Specifically, Al, Ti, Fe, Ni, Cu, Metal powder and metal fiber such as Zn, Ag, Sn, Si, or natural graphite, artificial graphite, various coke powders, mesophase carbon, vapor-grown carbon fiber, pitch-based carbon fiber, PAN-based carbon fiber, various resin firing Graphite such as a body can be used.
When adding the said electrically conductive agent, it is preferable to set it as 1-60 mass% with respect to the whole mixture after a coating process, especially 10-50 mass%, especially 20-50 mass% as addition amount of a conductive agent. If the amount added is too small, it may not be able to withstand expansion and contraction, and the cycle performance may be lowered. If it is too much, the charge / discharge capacity may be reduced.

また、上記リチウムイオン二次電池負極材を用いて負極を作製する場合、上記負極活物質と共に配合する結着剤としては、有機高分子結着剤を用いることが好ましく、該有機高分子結着剤としては、ポリエチレン、ポリプロピレン、ポリエチレンテレフタレート、芳香族ポリアミド、芳香族ポリイミド、セルロース、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、テトラフルオロエチレンを含む共重合フッ素ポリマーなどの高分子材料、スチレン・ブタジエンゴム、イソプレンゴム、ブタジエンゴム、エチレン・プロピレンゴム等のゴム状高分子材料、エチレン・酢酸ビニル共重合体、プロピレン・α−オレフィン共重合体等の軟質高分子材料、ポリエチレンオキサイド、ポリプロピレンオキサイド、ポリエピクロロヒドリン、ポリファゼン、ポリフッ化ビニリデン、ポリアクリロニトリル等の有機高分子材料にリチウム塩又はリチウムを主体とするアルカリ金属塩を複合化した系等のイオン導電性高分子材料を例示することができる。   Further, when a negative electrode is produced using the negative electrode material of the lithium ion secondary battery, an organic polymer binder is preferably used as the binder to be blended with the negative electrode active material, and the organic polymer binder is used. As the agent, polymer materials such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, aromatic polyimide, cellulose, polyvinylidene fluoride, polytetrafluoroethylene, copolymer fluoropolymer containing tetrafluoroethylene, styrene / butadiene rubber, Rubber polymer materials such as isoprene rubber, butadiene rubber, ethylene / propylene rubber, soft polymer materials such as ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, polyethylene oxide, polypropylene oxide, polyepichloro Hydrin, poly Azen can be exemplified ionic conductive polymer material systems such complexed alkali metal salt composed mainly of polyvinylidene fluoride, an organic polymer material such as polyacrylonitrile lithium salt or lithium.

これらの有機高分子結着剤と上記導電性負極活物質との混合割合は、導電性負極活物質１００質量部に対して有機高分子結着剤が０．１〜３０質量部であることが好ましく、０．５〜２０質量部であることがより好ましく、１〜１５質量部であることが更に好ましい。結着剤が０．１質量部未満であると負極活物質を保持するための結着力が十分ではなく、サイクル性が低下する場合があり、３０質量部より多いとバインダーが負極活物質全般を被覆し電極の抵抗が増大するため高いレートでの充放電が困難になる場合がある。   The mixing ratio of the organic polymer binder and the conductive negative electrode active material is such that the organic polymer binder is 0.1 to 30 parts by mass with respect to 100 parts by mass of the conductive negative electrode active material. Preferably, it is 0.5-20 mass parts, More preferably, it is 1-15 mass parts. If the binder is less than 0.1 part by mass, the binding force for holding the negative electrode active material may not be sufficient, and the cycle performance may be reduced. Since the resistance of the coated electrode increases, charging / discharging at a high rate may be difficult.

また、これらの有機高分子結着剤の他に、粘度調整剤としてカルボキシメチルセルロース、ポリアクリル酸ソーダ、その他のアクリル系ポリマー等を添加してもよい。   In addition to these organic polymer binders, carboxymethyl cellulose, polysodium acrylate, other acrylic polymers, and the like may be added as viscosity modifiers.

本発明において、リチウムイオン二次電池負極材は、例えば以下のようにしてリチウムイオン二次電池用負極成形体とすることができる。例えば、上記負極活物質と、有機高分子結着剤と、必要により導電剤と、その他の添加剤とに、Ｎ−メチルピロリドン、ジメチルホルムアミド、ジメチルスルホキシド等の溶剤を混練してペースト状の合剤にし、該合剤をシート状に集電体に塗布する。この場合、集電体としては、負極の電位において、化学的及び電気化学的に安定な、銅、ニッケル、ステンレス鋼等の金属箔又はそれら集電体表面を粗面化した金属箔等を使用することができる。なお、合剤をシート状に成形する成形方法は特に限定されず、公知の方法を用いることができる。この合剤表面を下記粗化処理方法によって粗化処理することにより、電極表面に微細な凹凸を形成したリチウムイオン二次電池負極材を得ることができる。   In the present invention, the negative electrode material for a lithium ion secondary battery can be formed into a negative electrode molded body for a lithium ion secondary battery, for example, as follows. For example, the negative electrode active material, the organic polymer binder, if necessary, the conductive agent, and other additives are kneaded with a solvent such as N-methylpyrrolidone, dimethylformamide, dimethylsulfoxide, and the like. The mixture is applied to the current collector in sheet form. In this case, as the current collector, a metal foil such as copper, nickel, stainless steel, or the like whose surface is roughened is used which is chemically and electrochemically stable at the potential of the negative electrode. can do. In addition, the shaping | molding method which shape | molds a mixture into a sheet form is not specifically limited, A well-known method can be used. By roughening the surface of the mixture by the following roughening method, a lithium ion secondary battery negative electrode material having fine irregularities formed on the electrode surface can be obtained.

ここで、電極の表面に微細な凹凸を持たせる方法としては、各種の方法を用いることができる。例えば、電極作製時に粗化処理を施した金属箔を電極合剤塗布面に張り合わせてロールプレスすることにより、粗化処理金属箔の粗化面を転写し、電極の表面に微細な凹凸を持たせる方法や、ショットブラスト等の機械的粗化処理により電極の合剤表面に微細な凹凸を持たせる方法、粗化処理銅箔に活物質をスパッタリングすることにより電極の合剤表面に微細な凹凸を持たせる方法等が挙げられる。これらの中でも、粗化処理を施した金属箔を電極合剤塗布面に張り合わせてロールプレスすることにより、粗化処理金属箔の粗化面を転写し、電極の表面に微細な凹凸を持たせる方法、機械的粗化処理により電極の合剤表面に微細な凹凸を持たせる方法が好ましい。   Here, various methods can be used as a method for giving fine irregularities on the surface of the electrode. For example, the roughened surface of the roughened metal foil is transferred by laminating the metal foil that has been roughened during electrode preparation to the electrode mixture coated surface and roll-pressed, so that the surface of the electrode has fine irregularities. A method of making the surface of the electrode mixture have fine irregularities by means of a mechanical roughening treatment such as shot blasting, and the surface of the electrode mixture having fine irregularities by sputtering an active material on the roughened copper foil. And a method of providing Among these, the roughened surface of the roughened metal foil is transferred and the surface of the electrode is given fine irregularities by laminating the roughened metal foil to the electrode mixture coating surface and roll pressing. The method and the method of giving a fine unevenness | corrugation to the mixture surface of an electrode by a mechanical roughening process are preferable.

このようにして得られる電極表面は、ＪＩＳ Ｂ ０６０１に規定する表面の算術平均粗さＲａが０．５μｍ以上、特に０．５〜１０μｍ、とりわけ０．５〜５μｍであることが好ましい。電極表面の算術平均粗さＲａが０．５μｍ未満であるとサイクル性能が低下する場合があり、算術平均粗さＲａが１０μｍより大きい場合にもサイクル性能が低下する場合がある。   The surface of the electrode thus obtained preferably has an arithmetic average roughness Ra of 0.5 μm or more, particularly 0.5 to 10 μm, particularly 0.5 to 5 μm, as defined in JIS B 0601. If the arithmetic average roughness Ra of the electrode surface is less than 0.5 μm, the cycle performance may be reduced, and if the arithmetic average roughness Ra is greater than 10 μm, the cycle performance may also be reduced.

このようにして得られたリチウムイオン二次電池負極材（非水電解質二次電池負極材）を用いることにより、リチウムイオン二次電池を製造することができる。
この場合、得られたリチウムイオン二次電池は、上記負極材を用いる点に特徴を有し、その他の正極、電解質、セパレーターなどの材料及び電池形状などは限定されない。例えば、正極活物質としては、ＬｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＭｎ2Ｏ4、Ｖ2Ｏ6、ＭｎＯ2、ＴｉＳ2、ＭｏＳ2などの遷移金属の酸化物及びカルコゲン化合物などが用いられる。電解質としては、例えば、過塩素酸リチウムなどのリチウム塩を含む非水溶液が用いられ、非水溶媒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、ジメトキシエタン、γ−ブチロラクトン、２−メチルテトラヒドロフランなどの単体又は２種類以上を組み合わせて用いられる。また、それ以外の種々の非水系電解質や固体電解質も使用できる。 By using the thus obtained lithium ion secondary battery negative electrode material (non-aqueous electrolyte secondary battery negative electrode material), a lithium ion secondary battery can be produced.
In this case, the obtained lithium ion secondary battery is characterized in that the negative electrode material is used, and other materials such as positive electrode, electrolyte, separator, and battery shape are not limited. For example, as the positive electrode active material, oxides of transition metals such as LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , V 2 O 6 , MnO 2 , TiS 2 , and MoS 2 , chalcogen compounds, and the like are used. As the electrolyte, for example, a non-aqueous solution containing a lithium salt such as lithium perchlorate is used, and as the non-aqueous solvent, propylene carbonate, ethylene carbonate, dimethoxyethane, γ-butyrolactone, 2-methyltetrahydrofuran or the like alone or in two types The above is used in combination. Various other non-aqueous electrolytes and solid electrolytes can also be used.

なお、以上は主としてリチウムイオン二次電池負極材について説明したが、上述した電極合剤表面の微細凹凸形成については、他の非水電解質二次電池の負極及び正極に対しても同様に適用でき、これによって上述した所期の効果を与えることができる。   Although the above has mainly described the negative electrode material for lithium ion secondary batteries, the above-described fine unevenness formation on the surface of the electrode mixture can be similarly applied to the negative electrode and positive electrode of other nonaqueous electrolyte secondary batteries. Thus, the desired effect described above can be provided.

以下、実施例及び比較例を示し、本発明を具体的に説明するが、本発明は下記の実施例に制限されるものではない。なお、下記の例において％は質量％を示し、表面の算術平均粗さＲａはＪＩＳ Ｂ ０６０１に記載の方法により測定した値を示し、平均粒子径は、レーザー光回折法による粒度分布測定における累積重量平均値（Ｄ50）又はメジアン径として測定した値を示す。 EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following examples,% indicates mass%, the arithmetic average roughness Ra of the surface indicates a value measured by the method described in JIS B 0601, and the average particle diameter is a cumulative value in the particle size distribution measurement by the laser light diffraction method. shows the weight average value to a value measured as (D 50) or median diameter.

［実施例１］
ブロック状又はフレーク状の酸化珪素（ＳｉＯxにおいてｘ＝１．０５）を、ヘキサンを分散媒としてボールミル及びビーズミルで粉砕し、得られた懸濁物をろ過し、窒素雰囲気下で脱溶剤後、平均粒子径が約８μｍの粉末を得た。次に、この酸化珪素粉末をロータリーキルンを用いて、Ａｒ／ＣＨ4ガス雰囲気中、１１００℃で１時間化学蒸着処理を行った。こうして得られた導電性珪素複合体をらいかい器で解砕し、蒸着炭素量３０％の導電性珪素複合体粉末を得た。 [Example 1]
Block-like or flaky silicon oxide (x = 1.05 in SiO x ) was pulverized with a ball mill and a bead mill using hexane as a dispersion medium, the obtained suspension was filtered, and after removing the solvent under a nitrogen atmosphere, A powder having an average particle size of about 8 μm was obtained. Next, this silicon oxide powder was subjected to chemical vapor deposition at 1100 ° C. for 1 hour in an Ar / CH 4 gas atmosphere using a rotary kiln. The conductive silicon composite obtained in this way was crushed with a cradle to obtain a conductive silicon composite powder having a vapor deposition carbon amount of 30%.

○電池評価
次に、以下の方法で得られた導電性珪素複合体粉末を負極活物質として用いて電池評価を行った。 Battery Evaluation Next, battery evaluation was performed using the conductive silicon composite powder obtained by the following method as a negative electrode active material.

まず、得られた導電性珪素複合体粉末にポリフッ化ビニリデンを１０％加え、更にＮ−メチルピロリドンを適量加え、スラリーとし、このスラリーを厚さ２０μｍの銅箔に塗布し、１２０℃で１時間乾燥後、ローラープレスにより電極を加圧成形した。このとき、加圧成形する活物質塗布面側に粗化処理された銅箔（表面の算術平均粗さＲａ６．５μｍ）を粗化処理面を活物質塗布面側に張り合わせてプレスし、電極表面を粗化処理し（表面の算術平均粗さＲａ４．０μｍ）、最終的には２０ｍｍφに打ち抜き、負極とした。   First, 10% of polyvinylidene fluoride is added to the obtained conductive silicon composite powder, and an appropriate amount of N-methylpyrrolidone is added to form a slurry. This slurry is applied to a copper foil having a thickness of 20 μm, and then at 120 ° C. for 1 hour. After drying, the electrode was pressure-formed by a roller press. At this time, a copper foil (arithmetic surface roughness Ra 6.5 μm) roughened on the active material coated surface side to be pressed is pressed with the roughened surface bonded to the active material coated surface side, and pressed. Was roughened (arithmetic surface roughness Ra 4.0 μm), and finally punched out to 20 mmφ to obtain a negative electrode.

ここで、得られた負極の充放電特性を評価するために、対極にリチウム箔を使用し、非水電解質として六フッ化リンリチウムをエチレンカーボネートと１，２−ジメトキシエタンの１／１（体積比）混合液に１モル／Ｌの濃度で溶解させた非水電解質溶液を用い、セパレーターに厚さ３０μｍのポリエチレン製微多孔質フィルムを用いた評価用リチウムイオン二次電池を作製した。   Here, in order to evaluate the charge / discharge characteristics of the obtained negative electrode, a lithium foil was used as a counter electrode, and lithium hexafluorophosphate was used as a non-aqueous electrolyte with 1/1 (volume) of ethylene carbonate and 1,2-dimethoxyethane. Ratio) A lithium ion secondary battery for evaluation using a non-aqueous electrolyte solution dissolved in a mixed solution at a concentration of 1 mol / L and a microporous polyethylene film having a thickness of 30 μm as a separator was prepared.

作製したリチウムイオン二次電池は、一晩室温で放置した後、二次電池充放電試験装置（（株）ナガノ製）を用い、テストセルの電圧が０Ｖに達するまで１ｍＡの定電流で充電を行い、０Ｖに達してからは、セル電圧を０Ｖに保つように電流を減少させて充電を行った。そして、電流値が２０μＡを下回った時点で充電を終了し、充電容量を求めた。また、放電は１ｍＡの定電流で行い、セル電圧が１．８Ｖを上回った時点で放電を終了し、放電容量を求めた。
以上の充放電試験を繰り返し、５０サイクル目に放電容量を測定し、５０サイクル後のサイクル保持率を求めた。これらの結果を表１に記す。 The prepared lithium ion secondary battery is left overnight at room temperature, and then charged with a constant current of 1 mA until the voltage of the test cell reaches 0 V using a secondary battery charge / discharge test device (manufactured by Nagano Co., Ltd.). After reaching 0V, charging was performed by decreasing the current so as to keep the cell voltage at 0V. Then, charging was terminated when the current value fell below 20 μA, and the charge capacity was determined. The discharge was performed at a constant current of 1 mA, and when the cell voltage exceeded 1.8 V, the discharge was terminated and the discharge capacity was determined.
The above charge / discharge test was repeated, the discharge capacity was measured at the 50th cycle, and the cycle retention after 50 cycles was determined. These results are shown in Table 1.

［実施例２］
実施例１で作製した蒸着炭素量３０％の導電性珪素複合体粉末を用いて電池評価を行い、ポリフッ化ビニリデンを１０％加え、更にＮ−メチルピロリドンを適量加えてスラリーとし、このスラリーを厚さ２０μｍの銅箔に塗布し、１２０℃で１時間乾燥後、ローラープレスにより電極を加圧成形した。このとき、加圧成形する活物質塗布面側に粗化処理された銅箔（表面の算術平均粗さＲａ９．０μｍ）を粗化処理面を活物質塗布面側に張り合わせてプレスし、電極表面を粗化処理し（表面の算術平均粗さＲａ５．０μｍ）、最終的には２０ｍｍφに打ち抜き、負極とした他は、実施例１と同様に充放電試験を行った。その結果を表１に記す。 [Example 2]
The battery was evaluated using the conductive silicon composite powder having a vapor deposition carbon amount of 30% produced in Example 1, 10% of polyvinylidene fluoride was added, and an appropriate amount of N-methylpyrrolidone was added to form a slurry. The film was applied to a copper foil having a thickness of 20 μm, dried at 120 ° C. for 1 hour, and then the electrode was pressure-formed by a roller press. At this time, a copper foil (arithmetic surface roughness Ra 9.0 μm) roughened on the active material coated surface side to be pressure-molded is pressed with the roughened surface bonded to the active material coated surface side, and pressed. Was subjected to a roughening treatment (arithmetic surface roughness Ra of 5.0 μm), finally punched out to 20 mmφ, and a charge / discharge test was conducted in the same manner as in Example 1 except that the negative electrode was used. The results are shown in Table 1.

［比較例１］
実施例１で作製した蒸着炭素量３０％の導電性珪素複合体粉末を用いて電池評価を行い、ポリフッ化ビニリデンを１０％加え、更にＮ−メチルピロリドンを適量加えてスラリーとし、このスラリーを厚さ２０μｍの銅箔に塗布し、１２０℃で１時間乾燥後、ローラープレスにより電極を加圧成形した。このとき、加圧成形する活物質塗布面側に圧延銅箔（表面の算術平均粗さＲａ０．３μｍ）を張り合わせてプレスし、電極表面を処理し（表面の算術平均粗さＲａ０．３μｍ）、最終的には２０ｍｍφに打ち抜き、負極とした他は、実施例１と同様に充放電試験を行った。その結果を表１に記す。 [Comparative Example 1]
The battery was evaluated using the conductive silicon composite powder having a vapor deposition carbon amount of 30% produced in Example 1, 10% of polyvinylidene fluoride was added, and an appropriate amount of N-methylpyrrolidone was added to form a slurry. The film was applied to a copper foil having a thickness of 20 μm, dried at 120 ° C. for 1 hour, and then the electrode was pressure-formed by a roller press. At this time, the rolled copper foil (surface arithmetic average roughness Ra 0.3 μm) is pressed on the active material coated surface side to be pressed and pressed to treat the electrode surface (surface arithmetic average roughness Ra 0.3 μm), A charge / discharge test was conducted in the same manner as in Example 1 except that the electrode was finally punched out to 20 mmφ and used as a negative electrode. The results are shown in Table 1.

Figure 2006012576
Figure 2006012576

Claims (8)

集電体に活物質、結着剤及び必要により導電剤を含む電極合剤を塗布してシート状に形成した正極又は負極からなる非水電解質二次電池用電極において、該電極の表面に微細な凹凸を形成してなることを特徴とする非水電解質二次電池用電極。   In a non-aqueous electrolyte secondary battery electrode comprising a positive electrode or a negative electrode formed into a sheet by applying an electrode mixture containing an active material, a binder and, if necessary, a conductive agent to a current collector, the surface of the electrode is fine An electrode for a non-aqueous electrolyte secondary battery, characterized by forming irregularities. 非水電解質二次電池用電極の負極であって、その負極活物質が、リチウムイオンを吸蔵、放出し得る材料であることを特徴とする請求項１記載の非水電解質二次電池用電極。   The electrode for a nonaqueous electrolyte secondary battery according to claim 1, wherein the electrode is a negative electrode for a nonaqueous electrolyte secondary battery, and the negative electrode active material is a material capable of occluding and releasing lithium ions. リチウムイオンを吸蔵、放出し得る材料が、珪素、珪素と二酸化珪素の複合分散体、一般式ＳｉＯx（１．０≦ｘ＜１．６）で表される酸化珪素、もしくはこれらの混合物、又はこれらの表面処理物であることを特徴とする請求項２記載の非水電解質二次電池用電極。 The material capable of inserting and extracting lithium ions is silicon, a composite dispersion of silicon and silicon dioxide, silicon oxide represented by the general formula SiO x (1.0 ≦ x <1.6), or a mixture thereof, or The non-aqueous electrolyte secondary battery electrode according to claim 2, which is a surface-treated product. 電極表面の算術平均粗さＲａが、０．５μｍ以上であることを特徴とする請求項１，２又は３記載の非水電解質二次電池用電極。   The electrode for a nonaqueous electrolyte secondary battery according to claim 1, 2 or 3, wherein the arithmetic mean roughness Ra of the electrode surface is 0.5 µm or more. 集電体に活物質、結着剤及び必要により導電剤を含む電極合剤を塗布してシート状の正極又は負極からなる非水電解質二次電池用電極を製造する方法において、集電体に電極合剤をシート状に塗布すると共に、このシート状電極合剤表面に微細な凹凸を形成することを特徴とする非水電解質二次電池用電極の作製方法。   In a method for producing a non-aqueous electrolyte secondary battery electrode comprising a sheet-like positive electrode or negative electrode by applying an electrode mixture containing an active material, a binder and, if necessary, a conductive agent to a current collector, A method for producing an electrode for a non-aqueous electrolyte secondary battery, wherein the electrode mixture is applied in a sheet shape, and fine irregularities are formed on the surface of the sheet electrode mixture. 電極表面の算術平均粗さＲａを０．５μｍ以上とすることを特徴とする請求項５記載の非水電解質二次電池用電極の作製方法。   6. The method for producing an electrode for a nonaqueous electrolyte secondary battery according to claim 5, wherein the arithmetic average roughness Ra of the electrode surface is 0.5 [mu] m or more. シート状電極合剤表面に粗化処理された金属箔を張り合わせてプレスすることにより電極表面に微細な凹凸を形成することを特徴とする請求項５又は６記載の非水電解質二次電池用電極の作製方法。   The electrode for a nonaqueous electrolyte secondary battery according to claim 5 or 6, wherein fine irregularities are formed on the electrode surface by laminating and pressing a roughened metal foil on the surface of the sheet electrode mixture. Manufacturing method. 機械的粗化処理によりシート状電極合剤表面に微細な凹凸を形成することを特徴とする請求項５又は６記載の非水電解質二次電池用電極の作製方法。
7. The method for producing an electrode for a nonaqueous electrolyte secondary battery according to claim 5 or 6, wherein fine irregularities are formed on the surface of the sheet-like electrode mixture by mechanical roughening treatment.
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