JP5219340B2 - Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery - Google Patents

Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery Download PDF

Info

Publication number
JP5219340B2
JP5219340B2 JP2006062790A JP2006062790A JP5219340B2 JP 5219340 B2 JP5219340 B2 JP 5219340B2 JP 2006062790 A JP2006062790 A JP 2006062790A JP 2006062790 A JP2006062790 A JP 2006062790A JP 5219340 B2 JP5219340 B2 JP 5219340B2
Authority
JP
Japan
Prior art keywords
negative electrode
lithium secondary
secondary battery
current collector
binder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2006062790A
Other languages
Japanese (ja)
Other versions
JP2007242405A (en
Inventor
靖幸 樟本
厚史 福井
博之 南
昌治 板谷
真理子 鳥前
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sanyo Electric Co Ltd
Original Assignee
Sanyo Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sanyo Electric Co Ltd filed Critical Sanyo Electric Co Ltd
Priority to JP2006062790A priority Critical patent/JP5219340B2/en
Publication of JP2007242405A publication Critical patent/JP2007242405A/en
Application granted granted Critical
Publication of JP5219340B2 publication Critical patent/JP5219340B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Landscapes

  • Cell Electrode Carriers And Collectors (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Description

本発明は、リチウム二次電池及びこのリチウム二次電池の負極に使用するリチウム二次電池用負極に係り、特に、ケイ素及び／又はケイ素合金を含む負極活物質粒子とバインダーとを含む負極合剤層が負極集電体の表面に形成されたリチウム二次電池用負極を用いたリチウム二次電池において、このリチウム二次電池用負極を改善して、リチウム二次電池における初期充放電効率及び充放電サイクル特性を向上させた点に特徴を有するものである。   The present invention relates to a lithium secondary battery and a negative electrode for a lithium secondary battery used for a negative electrode of the lithium secondary battery, and in particular, a negative electrode mixture containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder. In a lithium secondary battery using a negative electrode for a lithium secondary battery in which a layer is formed on the surface of the negative electrode current collector, the negative electrode for the lithium secondary battery is improved to improve the initial charge and discharge efficiency and charge in the lithium secondary battery. It is characterized in that the discharge cycle characteristics are improved.

近年、高出力，高エネルギー密度の新型二次電池として、非水電解液を用い、リチウムイオンを正極と負極との間で移動させて充放電を行うようにしたリチウム二次電池が利用されるようになった。   In recent years, lithium secondary batteries that use non-aqueous electrolyte and charge and discharge by moving lithium ions between positive and negative electrodes have been used as new secondary batteries with high output and high energy density. It became so.

ここで、このようなリチウム二次電池においては、その負極の１つとして、負極活物質にリチウムと合金化する材料を用い、この負極活物質粒子とバインダーとを含む負極合剤層を負極集電体の表面に形成したものが使用されている。   Here, in such a lithium secondary battery, as one of the negative electrodes, a material that is alloyed with lithium is used as the negative electrode active material, and the negative electrode mixture layer including the negative electrode active material particles and the binder is used as the negative electrode collector. What is formed on the surface of the electric body is used.

しかし、このように負極活物質としてリチウムと合金化する材料を用いたリチウム二次電池を充放電させた場合、リチウムを吸蔵・放出する際に、この負極活物質粒子の体積が膨張・収縮し、これにより負極合剤層中におけるバインダーが破壊され、また負極活物質が集電体から剥離し、これにより負極における集電性が悪くなって電池容量が低下し、リチウム二次電池の充放電サイクル特性が低下するという問題があった。特に、リチウム二次電池の容量を高めるために、リチウムと合金化する材料として、リチウムを吸蔵・放出する能力が大きいケイ素及び／又はケイ素合金を使用した場合、この負極活物質粒子の体積の膨張・収縮が大きくなり、充放電サイクル特性が大きく低下するという問題があった。   However, when a lithium secondary battery using a material that is alloyed with lithium as the negative electrode active material is charged and discharged in this way, the volume of the negative electrode active material particles expands and contracts when lithium is absorbed and released. Thus, the binder in the negative electrode mixture layer is destroyed, and the negative electrode active material is peeled off from the current collector, which deteriorates the current collecting property in the negative electrode, lowers the battery capacity, and charges / discharges the lithium secondary battery. There was a problem that the cycle characteristics deteriorated. In particular, in order to increase the capacity of the lithium secondary battery, when silicon and / or silicon alloy having a large ability to occlude and release lithium is used as a material to be alloyed with lithium, the volume of the negative electrode active material particles is expanded. -There was a problem that shrinkage was increased and charge / discharge cycle characteristics were greatly deteriorated.

また、近年においては、リチウム二次電池用負極のバインダーとしてポリイミド等の高強度の高分子材料を用いることが提案されている（例えば、特許文献１，２参照。）。   In recent years, it has been proposed to use a high-strength polymer material such as polyimide as a binder for a negative electrode for a lithium secondary battery (see, for example, Patent Documents 1 and 2).

しかし、リチウム二次電池用負極のバインダーとしてポリイミド等の高強度の高分子材料を用いた場合、初期充放電効率が低下し、また充放電サイクル特性を充分に向上させることができないという問題があった。
特開平１１−１５８２７７号 国際公開ＷＯ２００４／００４０３１ Ａ１ However, when a high-strength polymer material such as polyimide is used as a binder for a negative electrode for a lithium secondary battery, there are problems that initial charge / discharge efficiency is lowered and charge / discharge cycle characteristics cannot be sufficiently improved. It was.
JP-A-11-158277 International Publication WO2004 / 004031 A1

本発明は、ケイ素及び／又はケイ素合金を含む負極活物質粒子とバインダーとを含む負極合剤層が負極集電体の表面に形成されたリチウム二次電池用負極を用いたリチウム二次電池における上記のような問題を解決することを課題とするものである。   The present invention relates to a lithium secondary battery using a negative electrode for a lithium secondary battery in which a negative electrode mixture layer containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder is formed on the surface of a negative electrode current collector. It is an object to solve the above problems.

すなわち、本発明は、上記のようなリチウム二次電池において、ケイ素及び／又はケイ素合金を含む負極活物質粒子を用いた負極合剤層と負極集電体との密着力を向上させて、充放電によって電池容量が低下するのを抑制し、リチウム二次電池における初期充放電効率及び充放電サイクル特性を向上させることを課題とするものである。   That is, the present invention provides a lithium secondary battery having improved adhesion between a negative electrode mixture layer using a negative electrode active material particle containing silicon and / or a silicon alloy and a negative electrode current collector. It is an object of the present invention to suppress a decrease in battery capacity due to discharge and to improve initial charge / discharge efficiency and charge / discharge cycle characteristics in a lithium secondary battery.

本発明におけるリチウム二次電池用負極においては、上記のような課題を解決するため、ケイ素及び／又はケイ素合金を含む負極活物質粒子とバインダーとを含む負極合剤層が、非酸化性雰囲気下において４００℃以上で熱処理されて負極集電体の表面に形成された、リチウム二次電池用負極において、上記のバインダーとして、ポリイミド又はポリアミック酸からなるバインダー前駆体が上記の熱処理により分解されたイミド化合物を含むようにした。
In the negative electrode for a lithium secondary battery in the present invention, in order to solve the above problems, the negative electrode mixture layer containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder is in a non-oxidizing atmosphere. In the negative electrode for a lithium secondary battery formed on the surface of the negative electrode current collector by heat treatment at 400 ° C. or higher in FIG. 2, the binder precursor made of polyimide or polyamic acid is decomposed by the heat treatment as the binder. A compound was included.

ここで、上記のバインダーとして、下記の化１に示すイミド化合物を含むようにすることが望ましい。   Here, it is desirable to include an imide compound represented by the following chemical formula 1 as the binder.

また、上記のようなリチウム二次電池用負極を製造するにあたっては、ケイ素及び／又はケイ素合金を含む負極活物質粒子とポリイミド又はポリアミック酸からなるバインダー前駆体とを含む負極合剤スラリーを負極集電体の表面に塗布した後、これを非酸化性雰囲気下において４００℃以上で熱処理し、上記のバインダー前駆体を分解させて、イミド化合物からなるバインダーを形成することができる。なお、上記のように非酸化性雰囲気下で熱処理するのは、負極合剤層におけるバインダーや負極集電体が酸化されないようにするためである。 Further, in manufacturing the negative electrode for a lithium secondary battery as described above, a negative electrode mixture slurry containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder precursor made of polyimide or polyamic acid is collected. After coating on the surface of the electric body, it can be heat-treated at 400 ° C. or higher in a non-oxidizing atmosphere to decompose the binder precursor to form a binder composed of an imide compound. The reason why the heat treatment is performed in the non-oxidizing atmosphere as described above is to prevent the binder and the negative electrode current collector in the negative electrode mixture layer from being oxidized.

また、バインダーとして、上記の化１に示すイミド化合物を形成するにあたっては、上記のバインダー前駆体として、下記の化２に示すポリイミドを用いるようにする。   In forming the imide compound shown in Chemical Formula 1 as the binder, the polyimide shown in Chemical Formula 2 below is used as the binder precursor.

ここで、本発明において使用する上記の負極集電体としては、その表面粗さＲａが０．１μｍ以上のものを用いることが好ましい。このように表面粗さＲａが０．１μｍ以上の負極集電体を用い、この負極集電体の上に負極合剤層を形成すると、負極合剤層におけるバインダーによるアンカー効果が大きく得られて、この負極集電体と負極合剤層との密着性が大きく向上する。   Here, as said negative electrode collector used in this invention, it is preferable to use that whose surface roughness Ra is 0.1 micrometer or more. Thus, when the negative electrode current collector having a surface roughness Ra of 0.1 μm or more is used and the negative electrode mixture layer is formed on the negative electrode current collector, the anchor effect by the binder in the negative electrode mixture layer is greatly obtained. The adhesion between the negative electrode current collector and the negative electrode mixture layer is greatly improved.

そして、上記のように表面粗さＲａが０．１μｍ以上になった負極集電体を得るにあたっては、この負極集電体の表面を粗面化処理させるようにする。   Then, when obtaining the negative electrode current collector having a surface roughness Ra of 0.1 μm or more as described above, the surface of the negative electrode current collector is roughened.

ここで、このように負極集電体の表面を粗面化処理する方法としては、例えば、めっき法、気相成長法、エッチング法、研磨法等を用いることができる。   Here, as a method for roughening the surface of the negative electrode current collector in this way, for example, a plating method, a vapor phase growth method, an etching method, a polishing method, or the like can be used.

そして、めっき法としては、電解めっき法や無電解めっき法を用いることができる。また、気相成長法としては、スパッタリング法、ＣＶＤ法、蒸着法等を用いることができる。また、エッチング法としては、物理的エッチング法や化学的エッチング法を用いることができる。また、研磨法としては、サンドペーパーによる研磨やブラスト法による研磨等を行うことができる。   As a plating method, an electrolytic plating method or an electroless plating method can be used. Further, as the vapor phase growth method, a sputtering method, a CVD method, an evaporation method, or the like can be used. As an etching method, a physical etching method or a chemical etching method can be used. In addition, as a polishing method, polishing by sandpaper, polishing by a blast method, or the like can be performed.

また、この負極集電体の材料としては、例えば、銅、ニッケル、鉄、チタン、コバルト等の金属又はこれらの合金を用いることができ、特に、銅元素を含む金属箔を用いることが好ましく、更に好ましくは、銅箔又は銅合金箔を用いるようにする。また、上記の銅元素を含む金属箔としては、銅以外の金属元素から成る金属箔の表面に銅元素を含む層を形成したものであってもよい。   Moreover, as a material of the negative electrode current collector, for example, a metal such as copper, nickel, iron, titanium, cobalt, or an alloy thereof can be used, and in particular, a metal foil containing a copper element is preferably used. More preferably, a copper foil or a copper alloy foil is used. Moreover, as said metal foil containing a copper element, the layer containing a copper element may be formed in the surface of the metal foil which consists of metal elements other than copper.

また、上記の負極集電体の厚みは特に限定されないが、通常、１０μｍ〜１００μｍの範囲のものが使用される。   In addition, the thickness of the negative electrode current collector is not particularly limited, but usually a thickness in the range of 10 μm to 100 μm is used.

また、上記の負極集電体の表面粗さＲａの上限も特に限定されるものではないが、負極集電体の厚みが１０μｍ〜１００μｍの範囲にあることが好ましいので、実質的には表面粗さＲａの上限は１０μｍ以下になる。   Further, the upper limit of the surface roughness Ra of the negative electrode current collector is not particularly limited, but the thickness of the negative electrode current collector is preferably in the range of 10 μm to 100 μm. The upper limit of Ra is 10 μm or less.

また、上記の負極集電体としては、その表面粗さＲａと局部山頂の平均間隔Ｓとが１００Ｒａ≧Ｓの関係を有することが好ましい。ここで、表面粗さＲａ及び局部山頂の平均間隔Ｓは、日本工業規格（ＪＩＳ Ｂ ０６０１−１９９４）に規定されるものであり、例えば、表面粗さ計により測定することができる。   Moreover, as said negative electrode collector, it is preferable that the surface roughness Ra and the average space | interval S of a local peak have the relationship of 100Ra> = S. Here, the surface roughness Ra and the average distance S between the local peaks are defined by Japanese Industrial Standards (JIS B 0601-1994), and can be measured by, for example, a surface roughness meter.

また、この本発明において用いる負極活物質粒子は、上記のようにケイ素及び／又はケイ素合金を含むものであればよく、ケイ素及び／又はケイ素合金以外に、リチウムと合金化する材料を含むものであってもよい。ここで、リチウムと合金化する材料としては、例えば、ゲルマニウム、錫、鉛、亜鉛、マグネシウム、ナトリウム、アルミニウム、ガリウム、インジウム及びこれらの合金等を用いることができる。但し、この負極における容量を高めるためには、負極活物質粒子として上記のケイ素及び／又はケイ素合金だけを用いることが好ましく、特に、ケイ素を用いることが好ましい。   In addition, the negative electrode active material particles used in the present invention only need to contain silicon and / or a silicon alloy as described above, and contain a material that is alloyed with lithium in addition to silicon and / or a silicon alloy. There may be. Here, as a material to be alloyed with lithium, for example, germanium, tin, lead, zinc, magnesium, sodium, aluminum, gallium, indium, and alloys thereof can be used. However, in order to increase the capacity of the negative electrode, it is preferable to use only the above silicon and / or silicon alloy as the negative electrode active material particles, and it is particularly preferable to use silicon.

ここで、上記のケイ素合金としては、ケイ素と他の１種以上の元素と固溶体、ケイ素と他の１種以上の元素との金属間化合物、ケイ素と他の１種以上の元素との共晶合金等を用いることができる。また、このような合金の作製方法としては、アーク溶解法、液体急冷法、メカニカルアロイング法、スパッタリング法、化学気相成長法、焼成法等を用いることができる。   Here, examples of the silicon alloy include a solid solution of silicon and one or more other elements, an intermetallic compound of silicon and one or more other elements, and a eutectic of silicon and one or more other elements. An alloy or the like can be used. As a method for producing such an alloy, an arc melting method, a liquid quenching method, a mechanical alloying method, a sputtering method, a chemical vapor deposition method, a firing method, or the like can be used.

また、上記の負極活物質粒子の平均粒径は特に限定されないが、その粒径が大きくなるほど、負極活物質粒子と負極集電体との間の抵抗が低減される一方、充放電時における負極活物質粒子の体積変化による応力が負極集電体に直接作用して、負極合剤層が負極集電体から剥離しやすくなるため、負極活物質粒子の平均粒径が２０μｍ以下であることが好ましい。一方、負極活物質粒子の粒径が小さくなりすぎると、単位重量あたりの負極活物質粒子の表面積が増大して、非水電解液と接触する面積が増大し、不可逆反応が増加して容量低下を招くため、負極活物質粒子の平均粒径が１μｍ以上であることが好ましい。   Further, the average particle diameter of the negative electrode active material particles is not particularly limited, but as the particle diameter increases, the resistance between the negative electrode active material particles and the negative electrode current collector is reduced, while the negative electrode during charge and discharge is reduced. Since the stress due to the volume change of the active material particles directly acts on the negative electrode current collector, and the negative electrode mixture layer easily peels from the negative electrode current collector, the average particle size of the negative electrode active material particles may be 20 μm or less. preferable. On the other hand, when the particle size of the negative electrode active material particles becomes too small, the surface area of the negative electrode active material particles per unit weight increases, the area in contact with the non-aqueous electrolyte increases, the irreversible reaction increases, and the capacity decreases. Therefore, the average particle diameter of the negative electrode active material particles is preferably 1 μm or more.

また、この負極合剤層における導電性を高めて、負極における集電性を高めるため、この負極合剤層中に導電性粉末を添加させることができる。   Moreover, in order to improve the electroconductivity in this negative mix layer and to improve the current collection property in a negative electrode, electroconductive powder can be added in this negative mix layer.

ここで、上記の導電性粉末としては、上記の負極集電体と同様の材質のものを用いることが好ましく、具体的には、銅、ニッケル、鉄、チタン、コバルト等の金属や、これらの合金や、これらの混合物を用いることができる。なお、負極合剤層に添加させる導電性粉末の平均粒径は特に限定されるものではないが、一般に１００μｍ以下であることが好ましく、更に好ましくは５０μｍ以下、最も好ましくは１０μｍ以下のものを用いるようにする。   Here, as the conductive powder, it is preferable to use the same material as the negative electrode current collector, specifically, metals such as copper, nickel, iron, titanium, cobalt, An alloy or a mixture thereof can be used. The average particle size of the conductive powder added to the negative electrode mixture layer is not particularly limited, but generally it is preferably 100 μm or less, more preferably 50 μm or less, and most preferably 10 μm or less. Like that.

そして、前記のように熱処理して負極合剤層を負極集電体の表面に形成するにあたり、非酸化性雰囲気下で熱処理すると、負極合剤層におけるバインダーや負極集電体が酸化されるのが防止される。   When the heat treatment is performed as described above to form the negative electrode mixture layer on the surface of the negative electrode current collector, the binder and the negative electrode current collector in the negative electrode mixture layer are oxidized by heat treatment in a non-oxidizing atmosphere. Is prevented.

また、前記のように熱処理するにあたっては、熱処理する温度を前記のポリイミド又はポリアミック酸からなるバインダー前駆体の分解開始温度以上で行うようにする。このようにすると、ポリイミド又はポリアミック酸からなるバインダー前駆体が適切に分解されて、前記のイミド化合物からなるバインダーが形成されるようになると共に、バインダー前駆体が溶融等によりその粘度が低下して、バインダーが負極活物質粒子や負極集電体に接触する面積が増大し、負極合剤層と負極集電体との密着力が大きく向上されると共に、バインダー前駆体の分解によって負極合剤層中に空孔が生成され、これにより負極活物質粒子の膨張、収縮による応力が緩和されると共に、負極中への非水電解液の浸透性が良好になるため、電池における初期充放電効率が向上すると共に、充放電サイクルによる容量低下も抑制される。   In addition, when the heat treatment is performed as described above, the heat treatment temperature is set to be equal to or higher than the decomposition start temperature of the binder precursor made of the polyimide or polyamic acid. As a result, the binder precursor made of polyimide or polyamic acid is appropriately decomposed to form a binder made of the imide compound, and the viscosity of the binder precursor is lowered due to melting or the like. The area where the binder comes into contact with the negative electrode active material particles and the negative electrode current collector is increased, the adhesion between the negative electrode mixture layer and the negative electrode current collector is greatly improved, and the negative electrode mixture layer is decomposed by the decomposition of the binder precursor. As a result, pores are generated, thereby relieving stress due to expansion and contraction of the negative electrode active material particles and improving the permeability of the non-aqueous electrolyte into the negative electrode. While improving, the capacity | capacitance fall by a charging / discharging cycle is also suppressed.

また、本発明のリチウム二次電池においては、正極と負極と非水電解質とを備えたリチウム二次電池において、その負極に上記のリチウム二次電池用負極を用いるようにした。   In the lithium secondary battery of the present invention, in the lithium secondary battery including the positive electrode, the negative electrode, and the nonaqueous electrolyte, the above-described negative electrode for a lithium secondary battery is used as the negative electrode.

ここで、本発明のリチウム二次電池において使用する非水電解質は特に限定されず、一般に使用されているものを用いることかでき、例えば、非水系溶媒に溶質を溶解させた非水電解液や、ポリエチレンオキシド，ポリアクリロニトリル等のポリマー電解質に上記の非水電解液を含浸させたゲル状ポリマー電解質や、ＬｉＩ，Ｌｉ3Ｎ等の無機固体電解質を用いることができる。 Here, the nonaqueous electrolyte used in the lithium secondary battery of the present invention is not particularly limited, and any commonly used one can be used. For example, a nonaqueous electrolyte obtained by dissolving a solute in a nonaqueous solvent, Further, a gel polymer electrolyte obtained by impregnating the above-mentioned non-aqueous electrolyte into a polymer electrolyte such as polyethylene oxide or polyacrylonitrile, or an inorganic solid electrolyte such as LiI or Li 3 N can be used.

また、上記の非水系溶媒についても特に限定されず、一般に使用されているものを用いることかでき、例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート等の環状カーボネートと、ジメチルカーボネート、エチルメチルカーボネート、ジエチルカーボネート等の鎖状カーボネートとの混合溶媒や、環状カーボネートと１，２−ジメトキシエタン、１，２−ジエトキシエタン等のエーテル系溶媒との混合溶媒を使用することができる。   Further, the above non-aqueous solvent is not particularly limited, and those commonly used can be used. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl A mixed solvent of a chain carbonate such as carbonate or a mixed solvent of a cyclic carbonate and an ether solvent such as 1,2-dimethoxyethane or 1,2-diethoxyethane can be used.

また、上記の溶質についても特に限定されず、一般に使用されているものを用いることができ、例えば、ＬｉＰＦ6，ＬｉＢＦ4，ＬｉＣＦ3ＳＯ3，ＬｉＮ（ＣＦ3ＳＯ2）2，ＬｉＮ（Ｃ2Ｆ5ＳＯ2）2，ＬｉＮ（ＣＦ3ＳＯ2）（Ｃ4Ｆ9ＳＯ2），ＬｉＣ（ＣＦ3ＳＯ2）3，ＬｉＣ（Ｃ2Ｆ5ＳＯ2）3，ＬｉＡｓＦ6，ＬｉＣｌＯ4，Ｌｉ2Ｂ10Ｃｌ10，Ｌｉ2Ｂ12Ｃｌ12や、これらの混合物等を用いることができる。 Further, the solute is not particularly limited, and those commonly used can be used. For example, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2) 2, LiN (CF 3 SO 2) (C 4 F 9 SO 2), LiC (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3, LiAsF 6, LiClO 4, Li 2 B 10 Cl 10 , Li 2 B 12 Cl 12 , a mixture thereof, or the like can be used.

また、正極に使用する正極活物質についても特に限定されず、一般に使用されているものを用いることができ、例えば、ＬｉＣｏＯ2，ＬｉＮｉＯ2，ＬｉＭｎ2Ｏ4，ＬｉＭｎＯ2，ＬｉＣｏ0.5Ｎｉ0.5Ｏ2，ＬｉＮｉ0.7Ｃｏ0.2Ｍｎ0.1Ｏ2等のリチウム含有遷移金属酸化物や、ＭｎＯ2などのリチウムを含有していない金属酸化物等を用いることができる。 Further, there is no particular limitation on the positive electrode active material used in the positive electrode, in general there can be used those which are used, for example, LiCoO 2, LiNiO 2, LiMn 2 O 4, LiMnO 2, LiCo 0.5 Ni 0.5 O 2 , LiNi 0.7 Co 0.2 Mn 0.1 O 2 and other lithium-containing transition metal oxides, MnO 2 and other metal oxides not containing lithium, and the like can be used.

本発明におけるリチウム二次電池用負極においては、前記のようにケイ素及び／又はケイ素合金を含む負極活物質粒子とバインダーとを含む負極合剤層を負極集電体の表面に熱処理して形成するにあたり、バインダーとして、ポリイミド又はポリアミック酸からなるバインダー前駆体が熱処理により分解されたイミド化合物を含むようにしたため、ケイ素及び／又はケイ素合金を含む負極活物質粒子を用いた負極合剤層と負極集電体との密着力が向上し、負極合剤層が負極集電体から剥離するのが充分に抑制されるようになった。   In the negative electrode for a lithium secondary battery according to the present invention, as described above, a negative electrode mixture layer containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder is formed on the surface of the negative electrode current collector by heat treatment. In this case, since the binder precursor made of polyimide or polyamic acid contains an imide compound decomposed by heat treatment as a binder, a negative electrode mixture layer and a negative electrode collector using negative electrode active material particles containing silicon and / or a silicon alloy are used. Adhesive strength with the electric current is improved, and the negative electrode mixture layer is sufficiently suppressed from peeling from the negative electrode current collector.

また、本発明におけるリチウム二次電池においては、上記のようなリチウム二次電池用負極を用いたため、このリチウム二次電池を充放電させた場合に、上記の負極合剤層が負極集電体から剥離するのが充分に防止され、リチウム二次電池におけるサイクル寿命が向上すると共に、バインダーとしてポリイミド等の高強度の高分子材料を用いた場合のように初期充放電効率が低下するということもなくなった。   In the lithium secondary battery according to the present invention, since the negative electrode for a lithium secondary battery as described above is used, when the lithium secondary battery is charged and discharged, the negative electrode mixture layer becomes a negative electrode current collector. Is sufficiently prevented from peeling off, and the cycle life of the lithium secondary battery is improved, and the initial charge / discharge efficiency is lowered as in the case of using a high-strength polymer material such as polyimide as a binder. lost.

以下、本発明に係るリチウム二次電池用負極及びその製造方法、またこのリチウム二次電池用負極を用いたリチウム二次電池について実施例を挙げて具体的に説明すると共に、この実施例に係るリチウム二次電池においてはサイクル寿命や初期充放電効率が向上することを、比較例を挙げて明らかにする。なお、本発明は下記の実施例に示したものに限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施できるものである。   Hereinafter, the negative electrode for a lithium secondary battery according to the present invention, a method for producing the same, and a lithium secondary battery using the negative electrode for a lithium secondary battery will be described in detail with reference to examples. It will be clarified by giving a comparative example that the cycle life and the initial charge and discharge efficiency are improved in the lithium secondary battery. In addition, this invention is not limited to what was shown to the following Example, In the range which does not change the summary, it can change suitably and can implement.

（実施例１）
実施例１においては、下記のようにして作製した負極と正極と非水電解液とを用いるようにした。 Example 1
In Example 1, a negative electrode, a positive electrode, and a nonaqueous electrolytic solution prepared as described below were used.

［負極の作製］
負極活物質粒子として平均粒径が３μｍのケイ素粉末（純度９９．９％）を９０重量部、バインダー前駆体として下記の化３に示すポリイミドを１０重量部の割合にし、これに溶媒のＮ−メチル−２−ピロリドンを加え、これらを混合させて負極合剤スラリーを調製した。なお、このバインダー前駆体の分解開始温度は約３７０℃であった。 [Production of negative electrode]
90 parts by weight of silicon powder (purity 99.9%) having an average particle diameter of 3 μm as negative electrode active material particles and 10 parts by weight of polyimide shown in the following chemical formula 3 as a binder precursor were added to the N— Methyl-2-pyrrolidone was added and mixed to prepare a negative electrode mixture slurry. The decomposition start temperature of this binder precursor was about 370 ° C.

また、負極集電体としては、片面が電解により粗面化されてその表面粗さＲａが１．０μｍで、厚みが３５μｍになったものを用いた。   As the negative electrode current collector, one having one surface roughened by electrolysis and having a surface roughness Ra of 1.0 μm and a thickness of 35 μm was used.

そして、この負極集電体の粗面化された片面に上記の負極合剤スラリーを塗布し、これを乾燥させて、２５ｍｍ×３０ｍｍの大きさに切り抜き、圧延ローラにより圧延させた後、これをアルゴン雰囲気下において、前記のバインダー前駆体の分解開始温度以上の４００℃で１０時間熱処理して、負極集電体の片面に負極合剤層が形成された負極を作製した。   And after apply | coating said negative electrode mixture slurry to the roughened single side | surface of this negative electrode collector, this was dried, cut out to the magnitude | size of 25 mm x 30 mm, and rolled with the rolling roller, this was made into In an argon atmosphere, heat treatment was performed at 400 ° C., which is equal to or higher than the decomposition start temperature of the binder precursor, for 10 hours to produce a negative electrode in which a negative electrode mixture layer was formed on one side of the negative electrode current collector.

ここで、上記のように熱処理した場合に、上記の化３に示すポリイミドからなるバインダー前駆体がどのように変化するかを調べるため、化３に示すバインダー前駆体を含むＮ−メチル−２−ピロリドン溶液を乾燥させ、アルゴン雰囲気下において４００℃で１０時間熱処理し、得られた生成物を赤外吸収分光（ＩＲ）、核磁気共鳴（ＮＭＲ）、ガスクロマトグラフィ（ＧＣ）、質量分析（ＭＳ）により分析した結果、熱処理後の生成物は前記の化１に示すイミド化合物であることがわかった。   Here, in order to investigate how the binder precursor composed of polyimide shown in Chemical Formula 3 changes when heat-treated as described above, N-methyl-2-containing a binder precursor shown in Chemical Formula 3 is used. The pyrrolidone solution was dried and heat-treated at 400 ° C. for 10 hours under an argon atmosphere. The obtained product was subjected to infrared absorption spectroscopy (IR), nuclear magnetic resonance (NMR), gas chromatography (GC), mass spectrometry (MS). As a result, it was found that the product after the heat treatment was the imide compound shown in Chemical Formula 1 above.

これは、前記の化３に示すバインダー前駆体において、炭化水素基（−Ｃ2Ｈ4−）の両側におけるエステル基（−ＣＯＯ−）が熱によって容易に分解するため、上記の熱処理により、このエステル基（−ＣＯＯ−）が分解した結果であると考えられる。 This is because the ester group (—COO—) on both sides of the hydrocarbon group (—C 2 H 4 —) is easily decomposed by heat in the binder precursor shown in Chemical Formula 3 above. This is considered to be a result of decomposition of the ester group (—COO—).

［正極の作製］
正極活物質を作製するにあたっては、Ｌｉ2Ｃｏ3とＣｏＣｏ3とを用い、Ｌｉ：Ｃｏの原子比が１：１になるように秤量して、これらを乳鉢で混合し、これを直径１７ｍｍの金型でプレスして加圧成形した後、これを空気中において、８００℃の温度で２４時間焼成してＬｉＣｏＯ2の焼成体を製造し、このＬｉＣｏＯ2の焼成体を乳鉢で粉砕して、平均粒径が２０μｍになったＬｉＣｏＯ2粉末を得た。 [Production of positive electrode]
In producing the positive electrode active material, Li 2 Co 3 and CoCo 3 were used and weighed so that the atomic ratio of Li: Co was 1: 1, and these were mixed in a mortar. after by press pressure molding in a mold, which in air, and calcined at a temperature of 800 ° C. 24 hours to produce a sintered body of LiCoO 2, a sintered body of this LiCoO 2 was pulverized in a mortar, LiCoO 2 powder having an average particle size of 20 μm was obtained.

そして、このＬｉＣｏＯ2粉末からなる正極活物質粒子９０重量部に対して、導電剤の人造黒鉛粉末５重量部と、バインダーのポリフッ化ビニリデンを５重量部含む５重量％のＮ−メチル−２−ピロリドン溶液を混合させて、正極合剤スラリーを調製した。 And, 5 parts by weight of N-methyl-2-containing 5 parts by weight of artificial graphite powder as a conductive agent and 5 parts by weight of polyvinylidene fluoride as a binder with respect to 90 parts by weight of the positive electrode active material particles made of LiCoO 2 powder. A pyrrolidone solution was mixed to prepare a positive electrode mixture slurry.

次いで、この正極合剤スラリーをアルミニウム箔からなる正極集電体の片面に塗布し、これを乾燥させて圧延した後、２０ｍｍ×２０ｍｍの大きさに切り抜いて、正極集電体の片面に正極合剤層が形成された正極を作製した。   Next, this positive electrode mixture slurry is applied to one side of a positive electrode current collector made of aluminum foil, dried and rolled, and then cut into a size of 20 mm × 20 mm, and the positive electrode current collector is cut into one side of the positive electrode current collector. A positive electrode on which an agent layer was formed was produced.

［非水電解液の作製］
非水電解液を作製するにあたっては、エチレンカーボネートとジエチレンカーボネートとを３：７の体積比で混合させた混合溶媒に、ＬｉＰＦ6を１モル／リットルの濃度になるように溶解させた後、これに二酸化炭素ガスを吹き込み、二酸化炭素ガスを０．４重量％溶解させて、非水電解液を作製した。 [Preparation of non-aqueous electrolyte]
In preparing the non-aqueous electrolyte, after dissolving LiPF 6 to a concentration of 1 mol / liter in a mixed solvent in which ethylene carbonate and diethylene carbonate are mixed at a volume ratio of 3: 7, Carbon dioxide gas was blown into the solution, and 0.4% by weight of carbon dioxide gas was dissolved to prepare a non-aqueous electrolyte.

そして、リチウム二次電池を作製するにあたっては、図１及び図２（Ａ），（Ｂ）に示すように、上記のように正極合剤層１１ａが形成された正極１１の正極集電体１１ｂに正極集電タブ１１ｃを取り付けると共に、負極合剤層１２ａが形成された負極１２の負極集電体１２ｂに負極集電タブ１２ｃを取り付け、上記の正極１１と負極１２との間に多孔質ポリエチレンからなるセパレータ１３を挟み込み、これをアルミニウムラミネートフィルムで構成された外装体１４内に挿入させると共に、この外装体１５内に上記の非水電解液を加え、その後、上記の正極集電タブ１１ｃと負極集電タブ１２ｃとを外部に取り出すようにして、上記の外装体１４の開口部を封口させた。   And in producing a lithium secondary battery, as shown in FIG.1 and FIG.2 (A), (B), the positive electrode collector 11b of the positive electrode 11 in which the positive mix layer 11a was formed as mentioned above. The negative electrode current collector tab 12c is attached to the negative electrode current collector 12b of the negative electrode 12 on which the negative electrode mixture layer 12a is formed, and the porous polyethylene is interposed between the positive electrode 11 and the negative electrode 12. The separator 13 is sandwiched and inserted into an outer package 14 made of an aluminum laminate film, and the non-aqueous electrolyte is added to the outer package 15, and then the positive electrode current collector tab 11c and The opening of the outer package 14 was sealed so that the negative electrode current collecting tab 12c was taken out.

（実施例２）
実施例２においては、上記の実施例１における負極の作製において、負極活物質粒子として平均粒径が６μｍのケイ素粉末（純度９９．９％）を用いるようにし、それ以外は、上記の実施例１の場合と同様にして負極を作製すると共に、リチウム二次電池を作製した。 (Example 2)
In Example 2, in the production of the negative electrode in Example 1 above, silicon powder having an average particle size of 6 μm (purity 99.9%) was used as the negative electrode active material particles, and otherwise, the above Example While producing the negative electrode similarly to the case of 1, the lithium secondary battery was produced.

（実施例３）
実施例３においては、上記の実施例１における負極の作製において、負極活物質粒子として平均粒径が６μｍのケイ素粉末（純度９９．９％）を用いるようにし、それ以外は、上記の実施例１の場合と同様にして負極を作製すると共に、リチウム二次電池を作製した。 (Example 3)
In Example 3, in the production of the negative electrode in Example 1 above, silicon powder (purity 99.9%) having an average particle diameter of 6 μm was used as the negative electrode active material particles, and otherwise, the above Example While producing the negative electrode similarly to the case of 1, the lithium secondary battery was produced.

（比較例１）
比較例１においては、上記の実施例１における負極の作製において、アルゴン雰囲気下において熱処理する温度を、前記のバインダー前駆体の分解開始温度より低い３００℃にし、それ以外は、上記の実施例１の場合と同様にして負極を作製すると共に、リチウム二次電池を作製した。 (Comparative Example 1)
In Comparative Example 1, in the production of the negative electrode in Example 1 above, the temperature for heat treatment in an argon atmosphere was set to 300 ° C., which was lower than the decomposition start temperature of the binder precursor. A negative electrode was produced in the same manner as in, and a lithium secondary battery was produced.

（比較例２）
比較例２においては、上記の実施例１における負極の作製において、負極合剤スラリーを調製するにあたり、バインダー前駆体として分解開始温度が約５５０℃である下記の化４に示すポリイミドを用いると共に、アルゴン雰囲気下において熱処理する温度を、前記のバインダー前駆体の分解開始温度より低い３５０℃にし、それ以外は、上記の実施例１と同様にして負極を作製すると共に、リチウム二次電池を作製した。 (Comparative Example 2)
In Comparative Example 2, in preparing the negative electrode in Example 1 above, in preparing the negative electrode mixture slurry, a polyimide shown in the following chemical formula 4 having a decomposition start temperature of about 550 ° C. was used as a binder precursor, The temperature for heat treatment in an argon atmosphere was set to 350 ° C., which was lower than the decomposition start temperature of the binder precursor, and the negative electrode was produced in the same manner as in Example 1 above, and a lithium secondary battery was produced. .

（比較例３）
比較例３においては、上記の実施例１における負極の作製において、負極合剤スラリーを調製するにあたり、バインダー前駆体として上記の比較例２と同じ分解開始温度が約５５０℃である化４に示すポリイミドを用いると共に、アルゴン雰囲気下において熱処理する温度を、上記のバインダー前駆体の分解開始温度より低い４００℃にし、それ以外は、上記の実施例１の場合と同様にして負極を作製すると共に、リチウム二次電池を作製した。 (Comparative Example 3)
In Comparative Example 3, the preparation of the negative electrode mixture slurry in the production of the negative electrode in Example 1 described above is shown in Chemical Formula 4 in which the same decomposition start temperature as in Comparative Example 2 is about 550 ° C. as a binder precursor. While using polyimide, the temperature of the heat treatment in an argon atmosphere is set to 400 ° C., which is lower than the decomposition start temperature of the binder precursor, and other than that, in the same manner as in Example 1 above, a negative electrode is produced. A lithium secondary battery was produced.

（比較例４）
比較例４においては、上記の実施例１における負極の作製において、負極合剤スラリーを調製するにあたり、バインダー前駆体として上記の比較例２と同じ分解開始温度が約５５０℃である化４に示すポリイミドを用いると共に、アルゴン雰囲気下において熱処理する温度を、上記のバインダー前駆体の分解開始温度より低い４５０℃にし、それ以外は、上記の実施例１の場合と同様にして負極を作製すると共に、リチウム二次電池を作製した。 (Comparative Example 4)
In Comparative Example 4, the preparation of the negative electrode mixture slurry in Example 1 described above is shown in Chemical Formula 4 in which the same decomposition start temperature as in Comparative Example 2 above is about 550 ° C. as a binder precursor. While using polyimide, the temperature of the heat treatment under an argon atmosphere is set to 450 ° C., which is lower than the decomposition start temperature of the binder precursor, and other than that, in the same manner as in Example 1 above, a negative electrode is produced. A lithium secondary battery was produced.

次に、上記のようにして作製した実施例１〜３及び比較例１〜４の各リチウム二次電池を、１．４ｍＡの定電流で１時間充電させた後、１４ｍＡの定電流で電池電圧が４．２Ｖになるまで充電させ、さらに４．２Ｖの定電圧で電流値が０．７ｍＡになるまで充電させた後、１４ｍＡの定電流で電池電圧が２．７５Ｖになるまで放電させて、１サイクル目の充放電を行った。   Next, the lithium secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 4 manufactured as described above were charged at a constant current of 1.4 mA for 1 hour, and then the battery voltage at a constant current of 14 mA. Is charged to 4.2 V, and further charged to a current value of 0.7 mA at a constant voltage of 4.2 V, and then discharged to a battery voltage of 2.75 V at a constant current of 14 mA. The first cycle charge / discharge was performed.

そして、この１サイクル目の充電容量Ｑａと１サイクル目の放電容量Ｑ1とから下記の式により、実施例１〜３及び比較例１〜４の各リチウム二次電池の初期充放電効率を求め、その結果を下記の表１に示した。   Then, the initial charge and discharge efficiency of each of the lithium secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 4 is obtained from the charge capacity Qa of the first cycle and the discharge capacity Q1 of the first cycle by the following formula. The results are shown in Table 1 below.

初期充放電効率（％）＝（Ｑ1／Ｑａ）×１００   Initial charge / discharge efficiency (%) = (Q1 / Qa) x 100

また、上記のようにして１サイクル目の充放電を行った実施例１〜３及び比較例１〜４の各リチウム二次電池について、２サイクル目以降は、１４ｍＡの定電流で電池電圧が４．２Ｖになるまで充電させ、さらに４．２Ｖの定電圧で電流値が０．７ｍＡになるまで充電させた後、１４ｍＡの定電流で電池電圧が２．７５Ｖになるまで放電させ、このような充放電を繰り返して行い、２００サイクル目の放電容量Ｑ200を求め、１サイクル目の放電容量Ｑ1に対する２００サイクル後の容量維持率を下記の式により求め、その結果を下記の表１に示した。   Moreover, about each lithium secondary battery of Examples 1-3 and Comparative Examples 1-4 which performed charging / discharging of the 1st cycle as mentioned above, the battery voltage is 4 mA with a constant current of 14 mA after the 2nd cycle. Charge until .2V, and further charge at a constant voltage of 4.2V until the current value becomes 0.7mA, then discharge at a constant current of 14mA until the battery voltage reaches 2.75V. Charging / discharging was repeated to determine the discharge capacity Q200 at the 200th cycle, the capacity retention rate after 200 cycles with respect to the discharge capacity Q1 at the first cycle was determined by the following formula, and the results are shown in Table 1 below.

容量維持率（％）＝（Ｑ200／Ｑ1）×１００   Capacity maintenance rate (%) = (Q200 / Q1) x 100

この結果、前記の化３に示すポリイミドからなるバインダー前駆体が熱処理により分解されて、バインダーとしてイミド化合物が含まれる負極を用いた実施例１〜３の各リチウム二次電池は、前記の化３及び化４に示すポリイミドからなるバインダー前駆体が熱処理により分解されていない負極を用いた比較例１〜４の各リチウム二次電池に比べて、初期充放電効率が向上すると共に２００サイクル後の容量維持率も向上していた。   As a result, each of the lithium secondary batteries of Examples 1 to 3 using the negative electrode containing the imide compound as the binder was decomposed by heat treatment, and the lithium secondary battery of Examples 1 to 3 described above was converted to the chemical formula 3 described above. The initial charge / discharge efficiency is improved and the capacity after 200 cycles as compared with each of the lithium secondary batteries of Comparative Examples 1 to 4 using a negative electrode in which the binder precursor composed of polyimide shown in Chemical Formula 4 is not decomposed by heat treatment. The maintenance rate also improved.

また、実施例１〜３のリチウム二次電池においては、負極活物質粒子として平均粒径が３μｍ、６μｍ、１１μｍになった何れのケイ素粉末を用いた場合においても、上記のように初期充放電効率及び２００サイクル後の容量維持率が向上しており、特に、負極活物質粒子として平均粒径が６μｍになったケイ素粉末を用いた実施例２のリチウム二次電池においては、２００サイクル後の容量維持率が高い値を示し、充放電サイクル特性が大きく向上していた。   In the lithium secondary batteries of Examples 1 to 3, the initial charge / discharge was performed as described above when any silicon powder having an average particle size of 3 μm, 6 μm, or 11 μm was used as the negative electrode active material particles. In the lithium secondary battery of Example 2 using silicon powder having an average particle size of 6 μm as the negative electrode active material particles, the efficiency and capacity retention rate after 200 cycles were improved. The capacity retention ratio was high, and the charge / discharge cycle characteristics were greatly improved.

（実施例４）
実施例４においては、上記の実施例１における負極の作製において、負極集電体として、１８μｍの圧延コルソン合金箔の両面に銅を電析させて粗面化処理したものであって、両面の表面粗さＲａが０．１５μｍになったものを用いるようにした。 Example 4
In Example 4, in the production of the negative electrode in Example 1 described above, as a negative electrode current collector, copper was electrodeposited on both surfaces of a 18 μm rolled Corson alloy foil, and both surfaces were roughened. A surface roughness Ra of 0.15 μm was used.

そして、このように粗面化された負極集電体の両面に、上記の実施例１と同じ負極合剤スラリーを塗布し、これを乾燥させて、２５ｍｍ×３０ｍｍの大きさに切り抜き、圧延ローラにより圧延させた後、これをアルゴン雰囲気下において、前記のバインダー前駆体の分解開始温度以上の４００℃で１０時間熱処理して、負極集電体の両面に負極合剤層が形成された負極を作製した。   Then, the same negative electrode mixture slurry as in Example 1 was applied to both surfaces of the thus roughened negative electrode current collector, and this was dried, cut into a size of 25 mm × 30 mm, and a rolling roller Then, this was heat-treated for 10 hours at 400 ° C. above the decomposition start temperature of the binder precursor in an argon atmosphere to form a negative electrode in which a negative electrode mixture layer was formed on both sides of the negative electrode current collector. Produced.

また、リチウム二次電池を作製するにあたっては、上記の負極の両面に多孔質ポリエチレンからなるセパレータを介して上記の実施例１と同じ正極を配置させるようにし、それ以外は、上記の実施例１の場合と同様にして、リチウム二次電池を作製した。   Moreover, in producing a lithium secondary battery, the same positive electrode as that of the above-described Example 1 is disposed on both sides of the above-described negative electrode via separators made of porous polyethylene, and otherwise, the above Example 1 is used. A lithium secondary battery was produced in the same manner as in.

次に、上記のようにして作製した実施例４のリチウム二次電池を、２．８ｍＡの定電流で１時間充電させた後、２８ｍＡの定電流で電池電圧が４．２Ｖになるまで充電させ、さらに４．２Ｖの定電圧で電流値が１．４ｍＡになるまで充電させた後、２８ｍＡの定電流で電池電圧が２．７５Ｖになるまで放電させて、１サイクル目の充放電を行った。   Next, the lithium secondary battery of Example 4 manufactured as described above was charged with a constant current of 2.8 mA for 1 hour, and then charged with a constant current of 28 mA until the battery voltage reached 4.2V. Further, after charging at a constant voltage of 4.2 V until the current value became 1.4 mA, the battery was discharged at a constant current of 28 mA until the battery voltage reached 2.75 V, and the first cycle charge / discharge was performed. .

そして、この１サイクル目の充電容量Ｑａと１サイクル目の放電容量Ｑ1とから、上記の実施例１の場合と同様にして、実施例４のリチウム二次電池の初期充放電効率を求め、その結果を下記の表２に示した。   Then, from the charge capacity Qa of the first cycle and the discharge capacity Q1 of the first cycle, the initial charge / discharge efficiency of the lithium secondary battery of Example 4 is obtained in the same manner as in Example 1 above. The results are shown in Table 2 below.

また、上記のようにして１サイクル目の充放電を行った実施例４のリチウム二次電池について、２サイクル目以降は、２８ｍＡの定電流で電池電圧が４．２Ｖになるまで充電させ、さらに４．２Ｖの定電圧で電流値が１．４ｍＡになるまで充電させた後、２８ｍＡの定電流で電池電圧が２．７５Ｖになるまで放電させ、このような充放電を繰り返して行い、２００サイクル目の放電容量Ｑ200を求め、上記の実施例１の場合と同様にして、１サイクル目の放電容量Ｑ1に対する２００サイクル後の容量維持率を求め、その結果を下記の表２に示した。   In addition, the lithium secondary battery of Example 4 that was charged and discharged in the first cycle as described above was charged until the battery voltage reached 4.2 V at a constant current of 28 mA after the second cycle. After charging at a constant voltage of 4.2 V until the current value reaches 1.4 mA, the battery is discharged at a constant current of 28 mA until the battery voltage reaches 2.75 V, and such charge / discharge is repeated for 200 cycles. The discharge capacity Q200 of the eye was determined, and the capacity retention rate after 200 cycles with respect to the discharge capacity Q1 of the first cycle was determined in the same manner as in Example 1, and the results are shown in Table 2 below.

この結果、表面粗さＲａが０．１５μｍになった負極集電体の両面に、前記の化３に示すポリイミドからなるバインダー前駆体を含む負極合剤スラリーを塗布し、熱処理により前記のバインダー前駆体を分解させて、バインダーとしてイミド化合物が含まれる負極合剤層が形成された負極を用いた実施例４のリチウム二次電池も、表面粗さＲａが１．０μｍになった負極集電体の片面に上記の負極合剤層を形成した実施例１〜３の各リチウム二次電池と同様に、前記の化３及び化４に示すポリイミドからなるバインダー前駆体が熱処理により分解されていない負極を用いた比較例１〜４の各リチウム二次電池に比べて、初期充放電効率が向上すると共に２００サイクル後の容量維持率も向上していた。   As a result, a negative electrode mixture slurry containing a binder precursor made of polyimide shown in Chemical Formula 3 was applied to both surfaces of the negative electrode current collector having a surface roughness Ra of 0.15 μm, and the binder precursor was subjected to heat treatment. The lithium secondary battery of Example 4 using the negative electrode in which the negative electrode mixture layer containing the imide compound as a binder was formed was also used as the negative electrode current collector having a surface roughness Ra of 1.0 μm. Similarly to each of the lithium secondary batteries of Examples 1 to 3 in which the negative electrode mixture layer is formed on one surface of the negative electrode, the negative electrode in which the binder precursor composed of polyimide shown in Chemical Formula 3 and Chemical Formula 4 is not decomposed by heat treatment Compared to each of the lithium secondary batteries of Comparative Examples 1 to 4 using the battery, the initial charge / discharge efficiency was improved and the capacity retention rate after 200 cycles was also improved.

この発明の実施例及び比較例に係るリチウム二次電池の概略斜視図である。It is a schematic perspective view of the lithium secondary battery which concerns on the Example and comparative example of this invention. この発明の実施例１〜３及び比較例１〜４において作製したリチウム二次電池の内部を示した部分断面説明図である。It is the fragmentary sectional view showing the inside of the lithium secondary battery produced in Examples 1-3 of this invention and Comparative Examples 1-4.

符号の説明Explanation of symbols

１１ 正極
１１ａ 正極合剤層
１１ｂ 正極集電体
１１ｃ 正極集電タブ
１２ 負極
１２ａ 負極活物質層
１２ｂ 負極集電体
１２ｃ 負極集電タブ
１３ セパレータ
１４ 外装体 DESCRIPTION OF SYMBOLS 11 Positive electrode 11a Positive electrode mixture layer 11b Positive electrode collector 11c Positive electrode current collection tab 12 Negative electrode 12a Negative electrode active material layer 12b Negative electrode current collector 12c Negative electrode current collection tab 13 Separator 14 Exterior body

Claims (8)

ケイ素及び／又はケイ素合金を含む負極活物質粒子とバインダーとを含む負極合剤層が、非酸化性雰囲気下において４００℃以上で熱処理されて負極集電体の表面に形成された、リチウム二次電池用負極において、上記のバインダーとして、下記の化１に示すイミド化合物を含むことを特徴とするリチウム二次電池用負極。
A lithium secondary layer in which a negative electrode mixture layer containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder is heat-treated at 400 ° C. or higher in a non-oxidizing atmosphere and formed on the surface of the negative electrode current collector. A negative electrode for a lithium secondary battery, wherein the negative electrode for a battery includes an imide compound represented by the following chemical formula 1 as the binder.
請求項１に記載したリチウム二次電池用負極において、上記の負極集電体の表面粗さＲａが０．１μｍ以上であることを特徴とするリチウム二次電池用負極。 2. The negative electrode for a lithium secondary battery according to claim 1, wherein the negative electrode current collector has a surface roughness Ra of 0.1 μm or more. 請求項１又は請求項２に記載したリチウム二次電池用負極において、上記の負極集電体が、銅又は銅合金の箔、表面に銅又は銅合金の層が形成された金属箔から選択される１種であることを特徴とするリチウム二次電池用負極。 3. The negative electrode for a lithium secondary battery according to claim 1 or 2 , wherein the negative electrode current collector is selected from a copper or copper alloy foil and a metal foil having a copper or copper alloy layer formed on the surface. A negative electrode for a lithium secondary battery. 請求項３に記載したリチウム二次電池用負極において、上記の負極集電体が、電解銅箔、電解銅合金箔、表面に電解銅が設けられた金属箔及び表面に電解銅合金が設けられた金属箔から選択される１種であることを特徴とするリチウム二次電池用負極。 4. The negative electrode for a lithium secondary battery according to claim 3 , wherein the negative electrode current collector comprises an electrolytic copper foil, an electrolytic copper alloy foil, a metal foil provided with electrolytic copper on the surface, and an electrolytic copper alloy provided on the surface. A negative electrode for a lithium secondary battery, wherein the negative electrode is one selected from metal foils. 請求項１〜請求項４の何れか１項に記載したリチウム二次電池用負極において、上記の
負極活物質粒子の平均粒径が１μｍ〜２０μｍの範囲であることを特徴とするリチウム二次電池用負極。 In claim 1 or negative electrode for a lithium secondary battery according to one of claims 4, a lithium secondary battery wherein an average particle diameter of the negative electrode active material particles described above is in the range of 1μm~20μm Negative electrode. 請求項１〜請求項５の何れか１項に記載したリチウム二次電池用負極において、上記の負極活物質粒子がケイ素であることを特徴とするリチウム二次電池用負極。 The negative electrode for a lithium secondary battery according to any one of claims 1 to 5 , wherein the negative electrode active material particles are silicon. ケイ素及び／又はケイ素合金を含む負極活物質粒子と 下記の化２に示すポリイミドからなるバインダー前駆体とを含む負極合剤スラリーを負極集電体の表面に塗布した後、これを非酸化性雰囲気下において４００℃以上で熱処理し、上記のバインダー前駆体を分解させて、イミド化合物からなるバインダーを形成することを特徴とするリチウム二次電池用負極の製造方法。
A negative electrode mixture slurry containing negative electrode active material particles containing silicon and / or a silicon alloy and a binder precursor composed of polyimide shown in Chemical Formula 2 below is applied to the surface of the negative electrode current collector, and then applied to a non-oxidizing atmosphere. A method for producing a negative electrode for a lithium secondary battery, comprising: heat-treating at 400 ° C. or higher below to decompose the binder precursor to form a binder composed of an imide compound.
正極と負極と非水電解質とを備えたリチウム二次電池において、上記の負極に請求項１〜５の何れか１項に記載したリチウム二次電池用負極を用いたことを特徴とするリチウム二次電池。 A lithium secondary battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, wherein the negative electrode for a lithium secondary battery according to any one of claims 1 to 5 is used as the negative electrode. Next battery.
JP2006062790A 2006-03-08 2006-03-08 Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery Expired - Fee Related JP5219340B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2006062790A JP5219340B2 (en) 2006-03-08 2006-03-08 Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2006062790A JP5219340B2 (en) 2006-03-08 2006-03-08 Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery

Publications (2)

Publication Number Publication Date
JP2007242405A JP2007242405A (en) 2007-09-20
JP5219340B2 true JP5219340B2 (en) 2013-06-26

Family

ID=38587734

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2006062790A Expired - Fee Related JP5219340B2 (en) 2006-03-08 2006-03-08 Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery

Country Status (1)

Country Link
JP (1) JP5219340B2 (en)

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100848788B1 (en) * 2006-07-24 2008-07-30 주식회사 엘지화학 Electrode Assembly Having Electrode Tabs of the Same Size in Joint Portion thereof and Electrochemical Cell Containing the Same
JP5315665B2 (en) * 2007-10-31 2013-10-16 ソニー株式会社 Negative electrode for lithium ion secondary battery and lithium ion secondary battery
JP5361232B2 (en) * 2008-03-28 2013-12-04 三洋電機株式会社 Lithium secondary battery and manufacturing method thereof
JP4998358B2 (en) * 2008-04-08 2012-08-15 ソニー株式会社 Negative electrode for lithium ion secondary battery and lithium ion secondary battery
WO2009128319A1 (en) 2008-04-18 2009-10-22 株式会社豊田自動織機 Negative electrode for lithium ion secondary battery, and method for production thereof
WO2010100945A1 (en) 2009-03-06 2010-09-10 株式会社アイ．エス．テイ Binder composition for electrodes and electrode mix slurry
JPWO2010110205A1 (en) * 2009-03-24 2012-09-27 古河電気工業株式会社 Lithium ion secondary battery, battery electrode, electrolytic copper foil for battery electrode
JP5334021B2 (en) * 2009-03-31 2013-11-06 信越化学工業株式会社 LITHIUM SECONDARY BATTERY, METHOD FOR PRODUCING THE LITHIUM SECONDARY BATTERY, AND LITHIUM SECONDARY BATTERY negative electrode binder precursor solution used therein
JP2011048921A (en) * 2009-08-25 2011-03-10 Sanyo Electric Co Ltd Lithium secondary battery, and method of manufacturing the same
JP5583447B2 (en) 2010-03-26 2014-09-03 三洋電機株式会社 Lithium secondary battery and manufacturing method thereof
CN103053048A (en) * 2010-08-02 2013-04-17 日产自动车株式会社 Negative electrode for lithium-ion secondary battery, and manufacturing method for same
JPWO2012049889A1 (en) * 2010-10-14 2014-02-24 日本電気株式会社 Secondary battery and electrolyte for secondary battery used therefor
JP5450478B2 (en) 2011-02-28 2014-03-26 株式会社日立製作所 Non-aqueous secondary battery negative electrode and non-aqueous secondary battery
JP5761740B2 (en) * 2011-03-25 2015-08-12 国立研究開発法人産業技術総合研究所 Electrode and electrode forming method
JP5559757B2 (en) * 2011-09-07 2014-07-23 三井化学株式会社 Binder resin composition for lithium secondary battery, electrode paste using the same, and lithium ion secondary battery
US9160004B2 (en) * 2011-09-22 2015-10-13 Nec Corporation Lithium ion secondary battery
JP5590576B2 (en) * 2011-10-14 2014-09-17 独立行政法人産業技術総合研究所 Method for manufacturing electrode for power storage device, and power storage device
KR101706402B1 (en) * 2012-04-03 2017-02-14 삼성에스디아이 주식회사 Water soluble binder composition, and Electrode for a rechargeable battery employing the same
KR101637983B1 (en) * 2014-01-28 2016-07-12 주식회사 엘지화학 Surface coated cathode active material, preparation method thereof, and lithium secondary battery comprising the same
CN104409695B (en) * 2014-11-27 2016-08-17 江西先材纳米纤维科技有限公司 Flame deposited is heat-treated the method for modifying of silicon electrode
US11569508B2 (en) 2015-02-05 2023-01-31 Pi R&D Co., Ltd. Binder resin for lithium secondary battery electrode, electrode for lithium secondary battery, and lithium secondary battery
JP7197104B2 (en) 2015-11-30 2022-12-27 日本電気株式会社 lithium ion secondary battery
EP3386022B1 (en) 2015-11-30 2023-10-25 Nec Corporation Lithium ion secondary battery
KR102109087B1 (en) * 2016-03-31 2020-05-11 주식회사 엘지화학 Cathode with improved safety and lithium secondary battery comprising the same
JP2019164964A (en) * 2018-03-20 2019-09-26 Tdk株式会社 Negative electrode for lithium ion secondary battery and lithium ion secondary battery
CN110128653A (en) * 2019-05-28 2019-08-16 汕头市鲁汕化工原料有限公司 A kind of high-performance polyimide preparation method and its application in electrode of lithium cell
CN114843439A (en) * 2022-06-21 2022-08-02 合肥国轩高科动力能源有限公司 Composite magnesium-lithium alloy negative plate and preparation method and application thereof

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11158277A (en) * 1997-12-01 1999-06-15 Kanegafuchi Chem Ind Co Ltd Binder resin for battery electrode and its production
JP2000021412A (en) * 1998-07-06 2000-01-21 Hitachi Ltd Nonaqueous electrolyte secondary battery and manufacture thereof
JP2002008664A (en) * 2000-06-16 2002-01-11 Mitsubishi Heavy Ind Ltd Negative electrode for secondary battery and secondary battery using it
JP4033720B2 (en) * 2002-06-19 2008-01-16 三洋電機株式会社 Negative electrode for lithium secondary battery and lithium secondary battery

Also Published As

Publication number Publication date
JP2007242405A (en) 2007-09-20

Similar Documents

Publication Publication Date Title
JP5219340B2 (en) Negative electrode for lithium secondary battery, method for producing the same, and lithium secondary battery
JP4027255B2 (en) Negative electrode for lithium secondary battery and method for producing the same
JP5219339B2 (en) Lithium secondary battery
JP4212392B2 (en) Negative electrode for lithium secondary battery and lithium secondary battery
EP1635417B1 (en) Lithium secondary battery and method for producing same
JP4225727B2 (en) Negative electrode for lithium secondary battery and lithium secondary battery
JP4033720B2 (en) Negative electrode for lithium secondary battery and lithium secondary battery
US8343657B2 (en) Negative electrode for lithium secondary battery, method of manufacturing the electrode, and lithium secondary battery
KR101209338B1 (en) Lithium Secondary Battery
JP4497904B2 (en) Lithium secondary battery and manufacturing method thereof
JP4953583B2 (en) Lithium secondary battery
JP2007149604A (en) Negative electrode for lithium secondary battery and lithium secondary battery
JP2009099523A (en) Lithium secondary battery
JP3895932B2 (en) Negative electrode for lithium secondary battery and method for producing the same
JP4270894B2 (en) Negative electrode for lithium secondary battery and lithium secondary battery
JP4744076B2 (en) Lithium secondary battery and manufacturing method thereof
JP2007200686A (en) Negative electrode for lithium secondary battery and lithium secondary battery
JP4958405B2 (en) Nonaqueous electrolyte secondary battery
JP5268223B2 (en) Negative electrode for lithium secondary battery and lithium secondary battery
JP2008235083A (en) Negative electrode for lithium secondary battery, and lithium secondary cell
JP4436624B2 (en) Lithium secondary battery
JP2006092928A (en) Negative electrode for lithium secondary battery and lithium secondary battery
JP2006278123A (en) Nonaqueous electrolyte secondary battery
JP2007066726A (en) Lithium secondary battery, and manufacturing method of cathode for lithium secondary battery

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20090227

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20120120

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20120124

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20120309

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20121002

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20121109

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20130205

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20130305

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20160315

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20160315

Year of fee payment: 3

LAPS Cancellation because of no payment of annual fees