JP4546740B2 - Method for producing negative electrode for non-aqueous electrolyte secondary battery - Google Patents

Method for producing negative electrode for non-aqueous electrolyte secondary battery Download PDF

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JP4546740B2
JP4546740B2 JP2004002488A JP2004002488A JP4546740B2 JP 4546740 B2 JP4546740 B2 JP 4546740B2 JP 2004002488 A JP2004002488 A JP 2004002488A JP 2004002488 A JP2004002488 A JP 2004002488A JP 4546740 B2 JP4546740 B2 JP 4546740B2
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清隆 安田
暁宏 茂出木
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Mitsui Mining and Smelting Co Ltd
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Description

本発明は、リチウムイオン二次電池等の非水電解液二次電池用の負極の製造方法に関する。
The present invention relates to a method for producing a negative electrode for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

集電体上に、ケイ素を含む活物質の粒子、導電性金属粉末及びバインダーを含む混合層を形成し、該混合層を非酸化性雰囲気下に焼結することで活物質層を形成したリチウムイオン二次電池用負極が知られている（特許文献１参照）。また、集電体上にスズからなる活物質層を形成し、その上にめっき法やスパッタリング法によって銅からなる薄い被覆層を形成してなるリチウムイオン二次電池用負極も知られている（特許文献２参照）。   Lithium on which an active material layer is formed by forming a mixed layer containing active material particles containing silicon, a conductive metal powder and a binder on a current collector, and sintering the mixed layer in a non-oxidizing atmosphere An anode for an ion secondary battery is known (see Patent Document 1). There is also known a negative electrode for a lithium ion secondary battery in which an active material layer made of tin is formed on a current collector and a thin coating layer made of copper is formed thereon by a plating method or a sputtering method ( Patent Document 2).

特開２００２−２６０６３７号公報Japanese Patent Laid-Open No. 2002-260637 特開２００２−２８９１７８号公報JP 2002-289178 A

特許文献１記載の負極によれば高い充放電容量を得ることができるとされている。しかし、この負極では、活物質の粒子がリチウムを吸脱蔵することに起因する体積変化によって、活物質層が集電体から剥離しやすく、サイクル特性が十分とは言えない。この理由は、活物質層の形成時の焼結による熱によって集電体が軟質化するのに対して、活物質層はバインダーで固定化されていることから硬質であることに起因していると考えられる。またこの負極は、厚膜の集電体を備えていることから、単位重量当たり及び単位体積当たりのエネルギー密度を高めることが容易ではない。特許文献２記載の負極についても同様に、厚膜の集電体を備えていることから、単位重量当たり及び単位体積当たりのエネルギー密度を高めることが容易ではない。   According to the negative electrode described in Patent Document 1, a high charge / discharge capacity can be obtained. However, in this negative electrode, the active material layer easily peels from the current collector due to the volume change caused by the absorption and desorption of lithium by the active material particles, and the cycle characteristics are not sufficient. The reason for this is that the current collector is softened by heat due to sintering during the formation of the active material layer, whereas the active material layer is fixed with a binder and thus is hard. it is conceivable that. Moreover, since this negative electrode is provided with the thick film electrical power collector, it is not easy to raise the energy density per unit weight and per unit volume. Similarly, since the negative electrode described in Patent Document 2 includes a thick film current collector, it is not easy to increase the energy density per unit weight and per unit volume.

従って本発明は、前述した従来技術が有する種々の欠点を解消し得る非水電解液二次電池用負極の製造方法を提供することを目的とする。
Therefore, an object of this invention is to provide the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries which can eliminate the various fault which the prior art mentioned above has.

本発明は、キャリア箔の一面に、リチウム化合物の形成能の高い物質を含む活物質の粒子をバインダーで固定化して活物質層を形成し、The present invention forms an active material layer on one surface of a carrier foil by immobilizing active material particles containing a material capable of forming a lithium compound with a binder,
該活物質層を該キャリア箔ごと非酸化性雰囲気下に焼結処理に付し、The active material layer is subjected to a sintering treatment together with the carrier foil in a non-oxidizing atmosphere,
該活物質層の表面に、薄膜形成手段によってリチウム化合物の形成能の低い物質からなる導電性の被覆層を形成し、次いでOn the surface of the active material layer, a conductive coating layer made of a material having a low lithium compound forming ability is formed by a thin film forming means, and then
該活物質層を該被覆層と共に該キャリア箔から剥離することを特徴とする非水電解液二次電池用負極の製造方法を提供するものである。The present invention provides a method for producing a negative electrode for a nonaqueous electrolyte secondary battery, wherein the active material layer is peeled from the carrier foil together with the coating layer.

本発明の非水電解液二次電池用負極の製造方法によれば、被覆層が熱処理を受けていないので、該被覆層の硬質な状態が維持される。その結果、繰り返しの充放電に起因する活物質の粒子の剥落が防止され、サイクル特性が向上する。その上、集電用の厚膜導電体を有していないので単位重量当たり及び単位体積当たりのエネルギー密度を高めることができる。 According to the method for producing a negative electrode for a non-aqueous electrolyte secondary battery of the present invention, since the coating layer is not subjected to heat treatment, the hard state of the coating layer is maintained. As a result, exfoliation of active material particles due to repeated charge and discharge is prevented, and cycle characteristics are improved. In addition, since there is no thick film conductor for current collection, the energy density per unit weight and per unit volume can be increased.

以下本発明を、その好ましい実施形態に基づき図面を参照しながら説明する。図１には本発明の第１の実施形態の負極が模式的に示されている。図１に示す負極１は、リチウムイオン二次電池等の非水電解液二次電池に用いられるものであり、第１の面１ａ及び第２の面１ｂを有している。負極１は、活物質層２と、該活物質層２の一面に形成された被覆層３とを具備している。活物質層２の表面は、負極１における第１の面１ａをなしている。一方、被覆層３の表面は、負極１における第２の面１ｂをなしている。第１の面１ａは、負極１が電池に組み込まれたときに電解液と接する面である。一方、第２の面１ｂは、出力端子が引き出される面である。また図１から明らかなように、本実施形態の負極１は、従来の負極に用いられていた集電用の厚膜導電体（例えば金属箔やエキスパンドメタル）を有していない。   The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 schematically shows a negative electrode according to a first embodiment of the present invention. A negative electrode 1 shown in FIG. 1 is used for a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery, and has a first surface 1a and a second surface 1b. The negative electrode 1 includes an active material layer 2 and a coating layer 3 formed on one surface of the active material layer 2. The surface of the active material layer 2 forms the first surface 1 a of the negative electrode 1. On the other hand, the surface of the coating layer 3 forms the second surface 1 b of the negative electrode 1. The 1st surface 1a is a surface which contacts electrolyte solution when the negative electrode 1 is integrated in a battery. On the other hand, the second surface 1b is a surface from which the output terminal is drawn. As is clear from FIG. 1, the negative electrode 1 of the present embodiment does not have the current collecting thick film conductor (for example, metal foil or expanded metal) used in the conventional negative electrode.

活物質層２は、リチウム化合物の形成能の高い物質を含む活物質の粒子４及び導電性粉末５を含んでいる。活物質粒子４及び導電性粉末５は、バインダー（図示せず）によって固定化されている。バインダーの結着力によって活物質粒子４どうし及び活物質粒子４と導電性粉末５との密着性が高まり、電子伝導性が良好になる。更に、活物質粒子４の微粉化が抑制され、また被覆層３からの剥離が抑制されて、良好な充放電サイクル特性を得ることができる。「リチウム化合物の形成能が高い」とは、リチウムと金属間化合物又は固溶体を形成しやすいことを意味する。   The active material layer 2 includes active material particles 4 and a conductive powder 5 containing a material having a high ability to form a lithium compound. The active material particles 4 and the conductive powder 5 are fixed by a binder (not shown). Due to the binding force of the binder, the adhesion between the active material particles 4 and between the active material particles 4 and the conductive powder 5 is increased, and the electron conductivity is improved. Furthermore, the pulverization of the active material particles 4 is suppressed, and the peeling from the coating layer 3 is suppressed, so that good charge / discharge cycle characteristics can be obtained. “Lithium compound forming ability is high” means that an intermetallic compound or a solid solution is easily formed with lithium.

活物質層２は、活物質粒子４、導電性粉末５及びバインダーを含む層を非酸化性雰囲気下に焼結して形成されたものであることが好ましい。焼結によって活物質粒子４どうし及び活物質粒子４と導電性粉末５との密着性が高まり、活物質粒子４の周囲に導電性粉末５による強固な導電性のネットワークが形成される。その結果、充放電によって活物質粒子４が微粉化しても電子伝導性が保たれ、良好な充放電サイクル特性を得ることができる。   The active material layer 2 is preferably formed by sintering a layer containing the active material particles 4, the conductive powder 5, and the binder in a non-oxidizing atmosphere. Sintering increases the adhesion between the active material particles 4 and between the active material particles 4 and the conductive powder 5, and a strong conductive network is formed around the active material particles 4 by the conductive powder 5. As a result, even if the active material particles 4 are pulverized by charge / discharge, the electron conductivity is maintained, and good charge / discharge cycle characteristics can be obtained.

活物質層２に含まれている活物質粒子４は、その最大粒径が５０μｍ以下、特に２０μｍ以下であることが好ましい。また粒子４の粒径をＤ50値で表すと０．１〜８μｍ、特に１〜５μｍであることが好ましい。最大粒径が５０μｍ超であると、粒子４の脱落が起こりやすくなり、負極１の寿命が短くなる場合がある。粒径の下限値に特に制限はなく小さいほど好ましい。粒子４の製造方法に鑑みると、下限値は０．０１μｍ程度である。粒子４の粒径は、レーザー回折散乱式粒度測定装置、電子顕微鏡観察（ＳＥＭ観察）によって測定される。 The active material particles 4 contained in the active material layer 2 preferably have a maximum particle size of 50 μm or less, particularly 20 μm or less. Moreover, when the particle size of the particle 4 is expressed by a D 50 value, it is preferably 0.1 to 8 μm, particularly preferably 1 to 5 μm. When the maximum particle size is more than 50 μm, the particles 4 are likely to fall off, and the life of the negative electrode 1 may be shortened. There is no particular limitation on the lower limit of the particle size, and the smaller the better. In view of the method for producing the particles 4, the lower limit is about 0.01 μm. The particle size of the particles 4 is measured by a laser diffraction / scattering particle size measuring apparatus and electron microscope observation (SEM observation).

活物質粒子４としては、例えばシリコン系材料やスズ系材料、アルミニウム系材料、ゲルマニウム系材料等の粒子が挙げられる。特に、活物質としてシリコン系材料やスズ系材料を用いることが好ましい。シリコン系材料又はスズ系材料の粒子としては、例えばイ）シリコン単体又はスズ単体の粒子、ロ）少なくともシリコン又はスズと炭素との混合粒子、ハ）シリコン又はスズと金属との混合粒子、ニ）シリコン又はスズと金属との化合物粒子、ホ）シリコン又はスズと金属との化合物粒子と、金属の粒子との混合粒子、ヘ）シリコン単体又はスズ単体の粒子の表面に金属が被覆されてなる粒子などが挙げられる。ロ）、ハ）、ニ）、ホ）及びヘ）の粒子を用いると、イ）のシリコン単体又はスズ単体の粒子を用いる場合に比べて、リチウムの吸脱蔵に起因するシリコン系材料又はスズ系材料の微粉化が一層抑制されるという利点がある。また半導体であり電子伝導性の乏しいシリコンに電子伝導性を付与できるという利点がある。   Examples of the active material particles 4 include particles of silicon material, tin material, aluminum material, germanium material, and the like. In particular, it is preferable to use a silicon-based material or a tin-based material as the active material. Examples of the silicon-based material or tin-based material particles include: a) particles of silicon or tin, b) particles of at least silicon or tin and carbon, c) particles of silicon or tin and metal, and d) Compound particles of silicon or tin and metal, e) Mixed particles of compound particles of silicon or tin and metal and metal particles, f) Particles in which metal is coated on the surface of silicon or tin particles Etc. B), c), d), e), and f) particles, silicon-based materials or tin resulting from the absorption and desorption of lithium, compared to the case of b) using silicon or tin particles There is an advantage that the pulverization of the system material is further suppressed. Further, there is an advantage that electron conductivity can be imparted to silicon which is a semiconductor and has poor electron conductivity.

活物質層２に含まれている導電性粉末５は、活物質層２に十分な電子伝導性を付与するために用いられる。導電性粉末５としては、金属粉末及び非金属粉末を用いることができる。金属粉末としては、リチウム化合物の形成能の低い金属の粉末を用いることが好ましい。そのような金属としては、例えば銅、ニッケル、鉄、チタン若しくはコバルト又はこれらの組み合せからなる合金や混合物が挙げられる。一方、非金属粉末としては、例えばアセチレンブラックやグラファイトなどの導電性炭素材料の粒子が挙げられる。導電性粉末５は、その粒径が４０μｍ以下、特に２０μｍ以下であることが、電子伝導性の十分な付与の点から好ましい。導電性粉末５の粒径の下限値に特に制限はなく小さいほど好ましい。導電性粉末５の製造方法に鑑みると、その下限値は０．０１μｍ程度となる。   The conductive powder 5 contained in the active material layer 2 is used for imparting sufficient electronic conductivity to the active material layer 2. As the conductive powder 5, a metal powder and a non-metal powder can be used. As the metal powder, it is preferable to use a metal powder having a low ability to form a lithium compound. Examples of such a metal include copper, nickel, iron, titanium, cobalt, and alloys and mixtures made of combinations thereof. On the other hand, examples of the non-metallic powder include particles of a conductive carbon material such as acetylene black and graphite. The conductive powder 5 preferably has a particle size of 40 μm or less, particularly 20 μm or less from the viewpoint of providing sufficient electron conductivity. There is no restriction | limiting in particular in the lower limit of the particle size of the electroconductive powder 5, It is so preferable that it is small. In view of the method for producing the conductive powder 5, the lower limit is about 0.01 μm.

上述の通り、活物質層２には活物質粒子４及び導電性粉末５が含まれている。しかし、導電性粉末５は必須のものではなく、活物質粒子４が十分な電子伝導性を有している場合には、導電性粉末５を配合しなくてもよい。一方、導電性粉末５を配合する場合には、活物質層２における活物質粒子４の割合は、活物質粒子４と導電性粉末５との和に対し、重量比で表して９９〜６０重量％、特に９５〜８５重量％であることが、十分な充放電容量を確保しつつ、良好なサイクル特性を得る観点から好ましい。また活物質粒子４の負極全体に占める割合は、８０〜２０重量％、特に７０〜５０重量％であることが、十分な充放電容量の確保の点、及び活物質粒子４の剥落防止の点から好ましい。導電性粉末５の負極全体に占める割合は、１０〜１重量％、特に５〜２重量％であることが、十分な電子伝導性の確保、及び充放電容量の確保の点から好ましい。   As described above, the active material layer 2 includes the active material particles 4 and the conductive powder 5. However, the conductive powder 5 is not essential, and when the active material particles 4 have sufficient electronic conductivity, the conductive powder 5 may not be blended. On the other hand, when the conductive powder 5 is blended, the ratio of the active material particles 4 in the active material layer 2 is 99 to 60 weights expressed as a weight ratio with respect to the sum of the active material particles 4 and the conductive powder 5. %, Particularly 95 to 85% by weight, is preferable from the viewpoint of obtaining good cycle characteristics while ensuring a sufficient charge / discharge capacity. The proportion of the active material particles 4 in the whole negative electrode is 80 to 20% by weight, particularly 70 to 50% by weight, in order to secure a sufficient charge / discharge capacity and to prevent the active material particles 4 from peeling off. To preferred. The ratio of the conductive powder 5 to the whole negative electrode is preferably 10 to 1% by weight, and particularly preferably 5 to 2% by weight, from the viewpoint of ensuring sufficient electron conductivity and charge / discharge capacity.

活物質粒子４及び導電性粉末５と共に活物質層２に含まれているバインダーとしては、焼結後も完全に分解せず残存し得るものが好適に用いられる。例えばポリイミドを用いることができる。ポリイミドは、例えばポリアミド酸を熱処理することによって得ることができる。この熱処理によりポリアミド酸が脱水縮合してポリイミドが生成する。ポリイミドはそのイミド化率が８０％以上であることが、活物質粒子４と被覆層３との密着性向上の点から好ましい。イミド化率とは、ポリイミド前駆体に対する生成したポリイミドのモル％である。イミド化率８０％以上のものは、例えば、ポリアミド酸のＮ−メチルピロリドン溶液を１００℃〜４００℃の温度で１時間以上熱処理することによって得ることができる。例えば、３５０℃で熱処理する場合、熱処理時間が約１時間でイミド化率が約８０％となり、約３時間でイミド化率は約１００％となる。前述した通り、バインダーは焼結後も完全に分解せず残存していることが好ましいので、バインダーとしてポリイミドを用いる場合には、ポリイミドが完全に分解しない６００℃以下の温度で焼結することが好ましい。   As the binder contained in the active material layer 2 together with the active material particles 4 and the conductive powder 5, those that can remain without being completely decomposed after sintering are preferably used. For example, polyimide can be used. Polyimide can be obtained by heat-treating polyamic acid, for example. By this heat treatment, the polyamic acid is dehydrated and condensed to produce polyimide. The polyimide preferably has an imidation rate of 80% or more from the viewpoint of improving the adhesion between the active material particles 4 and the coating layer 3. The imidation ratio is a mol% of the produced polyimide with respect to the polyimide precursor. Those having an imidization rate of 80% or more can be obtained, for example, by heat-treating a polyamic acid N-methylpyrrolidone solution at a temperature of 100 ° C. to 400 ° C. for 1 hour or more. For example, when heat treatment is performed at 350 ° C., the imidation rate is about 80% after about 1 hour of heat treatment, and the imidation rate is about 100% after about 3 hours. As described above, it is preferable that the binder remains without being completely decomposed even after sintering. Therefore, when polyimide is used as the binder, sintering may be performed at a temperature of 600 ° C. or less at which the polyimide is not completely decomposed. preferable.

またバインダーとして、フッ素原子を含むバインダーも好ましく用いることができる。特に、ポリフッ化ビニリデン及びポリテトラフルオロエチレンが好ましい。ポリフッ化ビニリデン又はポリテトラフルオロエチレンをバインダーとして用い、バインダーが完全に分解しないような温度で焼結のための熱処理を行なうことにより、さらに良好な充放電サイクル特性を得ることができる。   A binder containing a fluorine atom can also be preferably used as the binder. In particular, polyvinylidene fluoride and polytetrafluoroethylene are preferable. By using polyvinylidene fluoride or polytetrafluoroethylene as a binder and performing a heat treatment for sintering at a temperature at which the binder does not completely decompose, better charge / discharge cycle characteristics can be obtained.

活物質層２において、バインダーは、固体成分（ここでは、活物質粒子４及び導電性粉末５）の総量に対して５〜３０重量％、特に５〜１５重量％存在していることが、活物質粒子４間及び活物質粒子４と導電性粉末５との密着性を十分に確保する点及び、活物質層２と被覆層３との密着性を十分に確保する点から好ましい。   In the active material layer 2, the binder is present in an amount of 5 to 30% by weight, particularly 5 to 15% by weight, based on the total amount of solid components (here, the active material particles 4 and the conductive powder 5). This is preferable from the viewpoint of sufficiently securing the adhesion between the material particles 4 and between the active material particles 4 and the conductive powder 5 and the adhesion between the active material layer 2 and the coating layer 3.

活物質層２の厚みは本発明において臨界的でないが、充放電容量を高める観点からは厚いことが好ましい。しかし厚すぎると活物質粒子４の剥落が起こりやすくなる。これらを考慮すると、活物質層２の厚みは５〜１００μｍ、特に１０〜３０μｍであることが好ましい。   The thickness of the active material layer 2 is not critical in the present invention, but is preferably thick from the viewpoint of increasing the charge / discharge capacity. However, if it is too thick, the active material particles 4 are likely to peel off. Considering these, the thickness of the active material layer 2 is preferably 5 to 100 μm, particularly preferably 10 to 30 μm.

被覆層３は導電性を有しており、本実施形態の負極１における集電機能を担っている。被覆層３はリチウム化合物の形成能の低い物質の薄層から構成されている。ここでいう薄層とは、従来の負極に用いられてきた集電用の厚膜導電体（集電体）の厚みよりも十分に薄い層であることをいう。このような薄層からなる被覆層３は、公知のあらゆる薄膜形成手段によって形成される。「リチウム化合物の形成能が低い」とは、リチウムと金属間化合物若しくは固溶体を形成しないか、又は形成したとしてもリチウムが微量であるか若しくは非常に不安定であることを意味する。具体的には銅、ニッケル、鉄、コバルト又はこれらの金属の合金などが挙げられる。これらの金属のうち銅及びニッケル或いはそれらの合金を用いることが特に好適である。負極１の強度を高める観点からはニッケルを用いることが好ましい。   The coating layer 3 has conductivity and has a current collecting function in the negative electrode 1 of the present embodiment. The covering layer 3 is composed of a thin layer of a material having a low lithium compound forming ability. The term “thin layer” as used herein refers to a layer that is sufficiently thinner than the thickness of a thick film conductor (current collector) for current collection that has been used in conventional negative electrodes. The coating layer 3 made of such a thin layer is formed by any known thin film forming means. “Lithium compound forming ability is low” means that lithium does not form an intermetallic compound or solid solution, or even if formed, lithium is in a very small amount or very unstable. Specific examples include copper, nickel, iron, cobalt, and alloys of these metals. Of these metals, it is particularly preferable to use copper and nickel or an alloy thereof. From the viewpoint of increasing the strength of the negative electrode 1, nickel is preferably used.

被覆層３は、活物質層２の表面に直接形成されている。活物質層２は活物質粒子４を含む集合体であるから、その表面は粗い状態になっている。そのような粗い状態になっている活物質層２の表面に被覆層３は直接形成されているので、活物質層２と被覆層３との接触面積は大きくなり、両者の密着性は高いものとなる。その結果、充放電を繰り返しても活物質層２と被覆層３との剥離が起こりづらくなる。   The coating layer 3 is formed directly on the surface of the active material layer 2. Since the active material layer 2 is an aggregate including the active material particles 4, the surface thereof is rough. Since the coating layer 3 is directly formed on the surface of the active material layer 2 in such a rough state, the contact area between the active material layer 2 and the coating layer 3 is large, and the adhesion between the two is high. It becomes. As a result, even if charging / discharging is repeated, peeling between the active material layer 2 and the coating layer 3 is difficult to occur.

後述する負極１の好適な製造方法から明らかなように、負極１における被覆層３は、加熱処理を受けていないので、硬質な状態が保たれている。その結果、活物質層２中の活物質粒子４が充放電によって膨張収縮しても、被覆層３が変形しづらくなり、活物質層２が被覆層３から剥離しづらくなる。従って、本実施形態の負極１は、先に述べた活物質粒子４の微粉化が抑制されることと相まって、サイクル特性が良好なものとなる。   As is apparent from a preferable method for manufacturing the negative electrode 1 described later, the coating layer 3 in the negative electrode 1 has not been subjected to a heat treatment, and thus a hard state is maintained. As a result, even if the active material particles 4 in the active material layer 2 expand and contract due to charge and discharge, the coating layer 3 is difficult to deform and the active material layer 2 is difficult to peel from the coating layer 3. Therefore, the negative electrode 1 of the present embodiment has good cycle characteristics in combination with the suppression of pulverization of the active material particles 4 described above.

先に述べた通り、負極１における被覆層３は薄層のものである。更に負極１は、従来の負極が有していた集電用の厚膜導電体を有していない。その結果、負極１は単位重量当たり及び単位体積当たりのエネルギー密度が、従来の負極に比較して極めて高いものとなる。負極１のエネルギー密度を高める観点から、被覆層３の厚みは１〜１０μｍ、特に２〜７μｍであることが好ましい。   As described above, the coating layer 3 in the negative electrode 1 is a thin layer. Further, the negative electrode 1 does not have the current collecting thick film conductor that the conventional negative electrode has. As a result, the negative electrode 1 has an extremely high energy density per unit weight and per unit volume compared to the conventional negative electrode. From the viewpoint of increasing the energy density of the negative electrode 1, the thickness of the coating layer 3 is preferably 1 to 10 μm, and particularly preferably 2 to 7 μm.

本実施形態の負極１は好適には図２（ａ）ないし（ｄ）に示す方法によって製造される。先ず図２（ａ）に示すように、キャリア箔１１を用意する。キャリア箔１１の材質に特に制限はない。キャリア箔１１は導電性であることが好ましい。この場合、導電性を有していれば、キャリア箔１１は金属製でなくてもよい。しかし金属製のキャリア箔１１を用いることで、負極の製造後にキャリア箔１１を溶解・製箔してリサイクルできるという利点がある。リサイクルの容易性を考慮すると、キャリア箔１１の材質は、表面層４の材質と同じであることが好ましい。キャリア箔１１は、負極を製造するための支持体として用いられるものであることから、製造工程においてヨレ等が生じないような強度を有していることが好ましい。従ってキャリア箔１１は、その厚みが１０〜５０μｍ程度であることが好ましい。   The negative electrode 1 of the present embodiment is preferably manufactured by the method shown in FIGS. First, as shown in FIG. 2A, a carrier foil 11 is prepared. There are no particular restrictions on the material of the carrier foil 11. The carrier foil 11 is preferably conductive. In this case, the carrier foil 11 may not be made of metal as long as it has conductivity. However, the use of the metal carrier foil 11 has an advantage that the carrier foil 11 can be melted, made into a foil and recycled after the production of the negative electrode. Considering the ease of recycling, the material of the carrier foil 11 is preferably the same as the material of the surface layer 4. Since the carrier foil 11 is used as a support for manufacturing the negative electrode, it is preferable that the carrier foil 11 has a strength that prevents the twist and the like from occurring in the manufacturing process. Therefore, the carrier foil 11 preferably has a thickness of about 10 to 50 μm.

キャリア箔１１は例えば電解や圧延で製造することができる。圧延で製造することで、表面粗さの低いキャリア箔１１を得ることができる。表面粗さの低いキャリア箔１１を用いることによって、後述する剥離層１１ａを形成しなくてもよくなるというメリットがある。一方キャリア箔１１を電解によって製造することで、キャリア箔１１の製造から負極の製造までをインラインで行うことができる。インラインで行うことは、負極の安定製造及び製造コストの低減の点から有利である。電解によってキャリア箔１１を製造する場合には、回転ドラムを陰極として用い、銅やニッケルなどの金属イオンを含む電解浴中で電解を行いドラム周面に金属を析出させる。析出した金属をドラム周面から剥離することでキャリア箔１１が得られる。   The carrier foil 11 can be manufactured by, for example, electrolysis or rolling. By manufacturing by rolling, carrier foil 11 with low surface roughness can be obtained. By using the carrier foil 11 having a low surface roughness, there is an advantage that it is not necessary to form a release layer 11a described later. On the other hand, by producing the carrier foil 11 by electrolysis, the production from the carrier foil 11 to the production of the negative electrode can be performed in-line. Performing in-line is advantageous in terms of stable production of the negative electrode and reduction in production cost. When the carrier foil 11 is manufactured by electrolysis, the rotating drum is used as a cathode, and electrolysis is performed in an electrolytic bath containing metal ions such as copper and nickel to deposit metal on the drum peripheral surface. The carrier foil 11 is obtained by peeling the deposited metal from the drum peripheral surface.

キャリア箔１１の表面粗さが低い場合には、キャリア箔１１の表面上に直接活物質層２を形成することができる。また図２（ａ）に示すように、キャリア箔１１の一面に剥離層１１ａを形成し、その上に活物質層２を形成してもよい。剥離層１１ａを形成することで、剥離を一層首尾良く行うことができる。また、キャリア箔１１に防錆効果を付与できるという利点もある。剥離層１１ａを形成するか否かにかかわらずキャリア箔１１の表面粗さＲａ（ＪＩＳ Ｂ ０６０１−１９９４）は０．０１〜３μｍ、特に０．０１〜１μｍ、とりわけ０．０１〜０．１８μｍであることが好ましい。この程度の低表面粗さであれば、剥離を首尾良く行うことができ、また剥離層１１ａを形成する場合には、厚みのムラのない剥離層１１ａを形成することができる。尤も、剥離層１１ａを形成する場合には、該剥離層１１ａによってキャリア箔１１の表面粗さが減殺されるので、キャリア箔１１ａの表面粗さＲａは前記の範囲よりも大きくても差し支えないこともある。   When the surface roughness of the carrier foil 11 is low, the active material layer 2 can be formed directly on the surface of the carrier foil 11. Moreover, as shown to Fig.2 (a), the peeling layer 11a may be formed in one surface of the carrier foil 11, and the active material layer 2 may be formed on it. By forming the peeling layer 11a, peeling can be performed more successfully. Further, there is an advantage that the carrier foil 11 can be given a rust prevention effect. Regardless of whether or not the release layer 11a is formed, the surface roughness Ra (JIS B 0601-1994) of the carrier foil 11 is 0.01 to 3 μm, particularly 0.01 to 1 μm, especially 0.01 to 0.18 μm. Preferably there is. With such a low surface roughness, the peeling can be carried out successfully, and when the peeling layer 11a is formed, the peeling layer 11a with no uneven thickness can be formed. However, when the release layer 11a is formed, the surface roughness Ra of the carrier foil 11 is reduced by the release layer 11a. Therefore, the surface roughness Ra of the carrier foil 11a may be larger than the above range. There is also.

剥離層１１ａは、例えばクロムめっき、ニッケルめっき、鉛めっき、クロメート処理等によって形成される。また、特開平１１−３１７５７４号公報の段落〔００３７〕〜〔００３８〕に記載の窒素含有化合物や硫黄含有化合物、特開２００１−１４００９０号公報の段落〔００２０〕〜〔００２３〕に記載の窒素含有化合物や硫黄含有化合物と銅微細粒との混合物などによって形成されてもよい。これらのうち、剥離性が良好な点から、クロムめっき、ニッケルめっき、鉛めっき又はクロメート処理によって剥離層１１ａが形成されることが好ましい。この理由は、これらの処理等によって剥離層１１ａの表面に酸化物あるいは酸塩の層が形成され、この層は、キャリア箔１１と活物質層２との密着性を低下させ剥離性を向上させる機能を有するからである。剥離層１１ａの厚みは０．０５〜３μｍであることが、首尾良く剥離を行い得る点から好ましい。剥離層１１ａが形成された後の該剥離層１１ａの表面粗さＲａは、キャリア箔１１上に活物質層２を直接形成する場合と同様に、０．０１〜３μｍ、特に０．０１〜１μｍ、とりわけ０．０１〜０．１８μｍであることが好ましい。   The release layer 11a is formed by, for example, chromium plating, nickel plating, lead plating, chromate treatment, or the like. Further, nitrogen-containing compounds and sulfur-containing compounds described in paragraphs [0037] to [0038] of JP-A-11-317574, and nitrogen-containing compounds described in paragraphs [0020] to [0023] of JP-A-2001-140090 are disclosed. You may form with the mixture of a compound, a sulfur containing compound, and copper fine grain. Among these, it is preferable that the peeling layer 11a is formed by chromium plating, nickel plating, lead plating, or chromate treatment from the viewpoint of good peelability. This is because an oxide or acid salt layer is formed on the surface of the release layer 11a by these treatments, and this layer reduces the adhesion between the carrier foil 11 and the active material layer 2 and improves the release property. It is because it has a function. The thickness of the release layer 11a is preferably 0.05 to 3 μm from the viewpoint that the release can be performed successfully. The surface roughness Ra of the release layer 11a after the release layer 11a is formed is 0.01 to 3 μm, particularly 0.01 to 1 μm, as in the case where the active material layer 2 is directly formed on the carrier foil 11. In particular, it is preferably 0.01 to 0.18 μm.

電解によって製造されるキャリア箔１１は、その製造方法に起因してその一方の面が平滑な光沢面となっており、他方の面が凹凸のあるマット面となっている。つまり各面の表面粗さが互いに異なっている。光沢面は、電解におけるドラム周面に対向していた面であり、マット面は析出面である。本製造方法においてキャリア箔１１に剥離層１１ａを形成する場合、光沢面及びマット面のどちらに剥離層１１ａを形成していてもよい。剥離性が良好であることを考慮すると、表面粗さの低い光沢面上に剥離層１１ａを形成することが好ましい。マット面上に剥離層１１ａを形成する場合には、例えば特開平９−１４３７８５号公報に記載の電解液添加剤を用いて電解を行って製造された箔を用いたり、剥離層１１ａの形成に先立ちマット面をエッチングすればよい。或いは圧延によってマット面の表面粗さを低下させてもよい。   The carrier foil 11 manufactured by electrolysis has a smooth glossy surface on one side due to the manufacturing method, and a matte surface with unevenness on the other side. That is, the surface roughness of each surface is different from each other. The glossy surface is a surface facing the drum peripheral surface in electrolysis, and the matte surface is a precipitation surface. When the release layer 11a is formed on the carrier foil 11 in this manufacturing method, the release layer 11a may be formed on either the glossy surface or the matte surface. Considering that the peelability is good, it is preferable to form the release layer 11a on a glossy surface having a low surface roughness. When the release layer 11a is formed on the mat surface, for example, a foil manufactured by electrolysis using an electrolytic solution additive described in JP-A-9-143785 is used, or the release layer 11a is formed. The mat surface may be etched in advance. Or you may reduce the surface roughness of a mat surface by rolling.

次に図２（ｂ）に示すように剥離層１１ａ上に、活物質粒子４、導電性粉末５及びバインダーを含む導電性スラリーを塗布して活物質層２を形成する。なお剥離層１１ａを形成しない場合にはキャリア箔１１の表面に直接活物質層２を形成する。スラリーは、前述の各成分を希釈溶媒に分散させて得られたものである。希釈溶媒としてはＮ−メチルピロリドン、シクロヘキサンなどが用いられる。形成された活物質層２は、キャリア箔１１ごと焼結処理に付される。焼結は非酸化性雰囲気下、例えば、窒素雰囲気下又はアルゴンなどの不活性ガス雰囲気下で行われる。水素雰囲気などの還元性雰囲気下で焼結を行ってもよい。焼結する際の熱処理の温度は、キャリア箔１１、活物質粒子４及び導電性粉末５の融点以下の温度であることが好ましい。例えば、キャリア箔１１及び導電性粉末５として銅を用いた場合には、融点である１０８３℃以下であることが好ましく、更に好ましくは２００〜５００℃であり、一層好ましくは３００〜４５０℃である。また、熱処理の温度をかかる範囲内にすることによって、焼結後に有効量のバインダーが残存するようになる。焼結する方法として、放電プラズマ焼結法やホットプレス法を用いることもできる。   Next, as shown in FIG. 2B, the active material layer 2 is formed by applying a conductive slurry containing the active material particles 4, the conductive powder 5, and the binder on the release layer 11 a. If the release layer 11a is not formed, the active material layer 2 is formed directly on the surface of the carrier foil 11. The slurry is obtained by dispersing the above-described components in a diluent solvent. As a diluting solvent, N-methylpyrrolidone, cyclohexane or the like is used. The formed active material layer 2 is subjected to a sintering process together with the carrier foil 11. Sintering is performed in a non-oxidizing atmosphere, for example, in a nitrogen atmosphere or an inert gas atmosphere such as argon. Sintering may be performed in a reducing atmosphere such as a hydrogen atmosphere. The temperature of the heat treatment at the time of sintering is preferably a temperature not higher than the melting points of the carrier foil 11, the active material particles 4 and the conductive powder 5. For example, when copper is used as the carrier foil 11 and the conductive powder 5, the melting point is preferably 1083 ° C. or less, more preferably 200 to 500 ° C., and further preferably 300 to 450 ° C. . Further, by setting the temperature of the heat treatment within such a range, an effective amount of binder remains after sintering. As a method of sintering, a discharge plasma sintering method or a hot press method can also be used.

焼結処理に付す前の活物質層２を、キャリア箔１１と共に圧延してもよい。圧延によって活物質層２における粒子の充填密度を高めることができ、粒子間の密着性を高めることができるので、良好な充放電サイクル特性を得ることができる。   The active material layer 2 before being subjected to the sintering treatment may be rolled together with the carrier foil 11. Since the packing density of the particles in the active material layer 2 can be increased by rolling and the adhesion between the particles can be increased, good charge / discharge cycle characteristics can be obtained.

活物質層２を焼結処理に付した後、図２（ｃ）に示すように、該活物質層２の表面に、被覆層３を形成する。被覆層３の形成には薄膜形成手段が用いられる。薄膜形成手段としては、電解めっき、無電解めっき、スパッタリング法、物理気相蒸着法、化学気相蒸着法又はダイレクトメタレーション法等を好適に用いることができる。なおダイレクトメタレーション法とは、例えば特開２００１−７３１５９号公報に記載されているように、ポリイミド樹脂のバインダーで固定化されている活物質層２の表面をアルカリ水溶液で処理して、ポリイミド樹脂のイミド環を開環してカルボキシル基を生成する工程、（２）カルボキシル基を中和する工程、（３）カルボキシル基を、銅又はパラジウム溶液で処理することにより、カルボキシル基の銅又はパラジウム塩を生成する工程、及び（４）銅又はパラジウム塩を還元して、ポリイミド樹脂表面に銅又はパラジウム金属の皮膜を形成する工程によって薄膜を形成する方法である。   After subjecting the active material layer 2 to the sintering treatment, a coating layer 3 is formed on the surface of the active material layer 2 as shown in FIG. A thin film forming means is used for forming the coating layer 3. As the thin film forming means, electrolytic plating, electroless plating, sputtering, physical vapor deposition, chemical vapor deposition, direct metalation, or the like can be suitably used. The direct metalation method is, for example, as described in JP-A-2001-73159, wherein the surface of the active material layer 2 fixed with a polyimide resin binder is treated with an alkaline aqueous solution to obtain a polyimide resin. A step of generating a carboxyl group by opening the imide ring, (2) a step of neutralizing the carboxyl group, (3) a copper or palladium salt of the carboxyl group by treating the carboxyl group with a copper or palladium solution And (4) reducing the copper or palladium salt to form a thin film by forming a copper or palladium metal film on the polyimide resin surface.

どのような薄膜形成手段を用いるかは、被覆層３の構成材料等に応じて決定すればよい。特に好ましい薄膜形成手段は電解めっきである。電解めっきを行う場合には、活物質層２が形成されたキャリア箔１１を、リチウム化合物の形成能の低い金属材料を含むめっき浴中に浸漬して電解めっきを行う。電解めっきの条件としては、例えばリチウム化合物の形成能の低い金属材料として銅を用いる場合、硫酸銅系溶液を用いるときには、銅の濃度を３０〜１００ｇ／ｌ、硫酸の濃度を５０〜２００ｇ／ｌ、塩素の濃度を３０ｐｐｍ以下とし、液温を３０〜８０℃、電流密度を１〜１００Ａ／ｄｍ2とすればよい。ピロ燐酸銅系溶液を用いる場合には、銅の濃度２〜５０ｇ／ｌ、ピロ燐酸カリウムの濃度１００〜７００ｇ／ｌとし、液温を３０〜６０℃、ｐＨを８〜１２、電流密度を１〜１０Ａ／ｄｍ2とすればよい。 What thin film forming means is used may be determined according to the constituent material of the coating layer 3 and the like. A particularly preferable thin film forming means is electrolytic plating. When performing electrolytic plating, the electrolytic plating is performed by immersing the carrier foil 11 on which the active material layer 2 is formed in a plating bath containing a metal material having a low lithium compound forming ability. As conditions for electrolytic plating, for example, when copper is used as a metal material having a low ability to form a lithium compound, when using a copper sulfate solution, the concentration of copper is 30 to 100 g / l, and the concentration of sulfuric acid is 50 to 200 g / l. The chlorine concentration may be 30 ppm or less, the liquid temperature may be 30 to 80 ° C., and the current density may be 1 to 100 A / dm 2 . When using a copper pyrophosphate solution, the concentration of copper is 2 to 50 g / l, the concentration of potassium pyrophosphate is 100 to 700 g / l, the liquid temperature is 30 to 60 ° C., the pH is 8 to 12, and the current density is 1. ~10A / dm 2 and may be set.

次に、図２（ｄ）に示すように、剥離層１１ａの部分において負極１をキャリア箔１１から剥離分離する。なお、図２（ｄ）では剥離層１１ａがキャリア箔１１側に残るように描かれているが、実際は剥離層１１ａはその厚さや剥離処理剤の種類によってキャリア箔１１側に残る場合もあれば、負極１側に残る場合もある。或いはこれら双方に残る場合もある。何れの場合であっても、剥離層１１ａはその厚みが極めて薄いので、得られる負極１の性能に何ら影響はない。   Next, as shown in FIG. 2D, the negative electrode 1 is peeled and separated from the carrier foil 11 in the peeling layer 11a. In FIG. 2D, the release layer 11a is depicted so as to remain on the carrier foil 11 side, but in reality, the release layer 11a may remain on the carrier foil 11 side depending on the thickness and the type of the release treatment agent. In some cases, it may remain on the negative electrode 1 side. Or it may remain in both of them. In any case, since the thickness of the release layer 11a is extremely thin, the performance of the obtained negative electrode 1 is not affected at all.

このようにして得られた負極１には、その第２の面１ｂ（図１参照）に出力端子が取り付けられる。次いで負極１は、公知の正極、セパレータ、非水系電解液と共に用いられて非水電解液二次電池となされる。この場合、先に述べた通り、負極１における第１の面１ａ（図１参照）が電解液に接するように用いられる。非水電解液二次電池における正極は、正極活物質並びに必要により導電剤及び結着剤を適当な溶媒に懸濁し、正極合剤を作製し、これを集電体に塗布、乾燥した後、ロール圧延、プレスし、さらに裁断、打ち抜きすることにより得られる。正極活物質としては、リチウムニッケル複合酸化物、リチウムマンガン複合酸化物、リチウムコバルト複合酸化物等の従来公知の正極活物質が用いられる。セパレーターとしては、合成樹脂製不織布、ポリエチレン又はポリプロピレン多孔質フイルム等が好ましく用いられる。非水電解液は、リチウム二次電池の場合、支持電解質であるリチウム塩を有機溶媒に溶解した溶液からなる。リチウム塩としては、例えば、ＬｉＣ１Ｏ4、ＬｉＡ１Ｃｌ4、ＬｉＰＦ6、ＬｉＡｓＦ6、ＬｉＳｂＦ6、ＬｉＳＣＮ、ＬｉＣ１、ＬｉＢｒ、ＬｉＩ、ＬｉＣＦ3ＳＯ3、ＬｉＣ4Ｆ9ＳＯ3等が例示される。 An output terminal is attached to the second surface 1b (see FIG. 1) of the negative electrode 1 thus obtained. Next, the negative electrode 1 is used together with a known positive electrode, separator, and nonaqueous electrolyte solution to form a nonaqueous electrolyte secondary battery. In this case, as described above, the first surface 1a (see FIG. 1) of the negative electrode 1 is used in contact with the electrolytic solution. The positive electrode in the non-aqueous electrolyte secondary battery is prepared by suspending a positive electrode active material and, if necessary, a conductive agent and a binder in a suitable solvent, preparing a positive electrode mixture, applying this to a current collector, and drying. It is obtained by roll rolling, pressing, and further cutting and punching. As the positive electrode active material, conventionally known positive electrode active materials such as lithium nickel composite oxide, lithium manganese composite oxide, and lithium cobalt composite oxide are used. As the separator, a synthetic resin nonwoven fabric, polyethylene, polypropylene porous film, or the like is preferably used. In the case of a lithium secondary battery, the nonaqueous electrolytic solution is a solution in which a lithium salt that is a supporting electrolyte is dissolved in an organic solvent. The lithium salt, for example, LiC1O 4, LiA1Cl 4, LiPF 6, LiAsF 6, LiSbF 6, LiSCN, LiC1, LiBr, LiI, etc. LiCF 3 SO 3, LiC 4 F 9 SO 3 are exemplified.

次に本発明の別の実施形態を図３に示す。図３に示す実施形態に関し、特に説明しない点については、図１に示す実施形態に関する説明が適宜適用される。また図３において図１と同じ部材には同じ符号を付してある。   Next, another embodiment of the present invention is shown in FIG. Regarding the embodiment shown in FIG. 3, the explanation regarding the embodiment shown in FIG. In FIG. 3, the same members as those in FIG.

図３に示す負極１０は、図１に示す負極１を二つ重ね合わせて構成されている。混同を避けるため、図３に示す実施形態に関する説明においては、図１に示す負極１を負極前駆体と呼ぶことにする。負極１０は、各負極前駆体における被覆層３どうしが当接するように両負極前駆体が貼り合わされて構成されている。その結果、負極１０は、２つの活物質層２，３を有している。そして、２つの活物質層２，３間には、各負極前駆体における被覆層３どうしが当接して形成された中間層６が位置している。２つの活物質層２，３の表面１ｃ，１ｃは、負極１０における外面をなしている。表面１ｃ，１ｃは、負極前駆体における第１の面１ａ（図１参照）に対応している。本発明においては、二つの負極前駆体を重ね合わせて負極１０を構成するだけでよい。つまり本発明で言う貼り合わせは、二つの負極前駆体を何らかの手段によって接合することのみならず、両者を単に重ね合わせることも包含するものである。両者の貼り合わせを強固にしたい場合には、導電性ペースト等の導電性接着材料を用いて両者を貼り合わせればよい。   A negative electrode 10 shown in FIG. 3 is formed by stacking two negative electrodes 1 shown in FIG. In order to avoid confusion, in the description of the embodiment shown in FIG. 3, the negative electrode 1 shown in FIG. 1 is referred to as a negative electrode precursor. The negative electrode 10 is configured by bonding both negative electrode precursors so that the coating layers 3 of the negative electrode precursors are in contact with each other. As a result, the negative electrode 10 has two active material layers 2 and 3. Between the two active material layers 2 and 3, an intermediate layer 6 formed by contacting the covering layers 3 in each negative electrode precursor is located. The surfaces 1 c and 1 c of the two active material layers 2 and 3 form the outer surface of the negative electrode 10. The surfaces 1c and 1c correspond to the first surface 1a (see FIG. 1) of the negative electrode precursor. In the present invention, it is only necessary to form the negative electrode 10 by superimposing two negative electrode precursors. In other words, the bonding referred to in the present invention includes not only joining the two negative electrode precursors by any means but also simply superimposing them. In order to strengthen the bonding between the two, the two may be bonded using a conductive adhesive material such as a conductive paste.

図３から明らかなように本実施形態の負極１０は、活物質層２，３が負極１０の各面１ｃ，１ｃに露出しているので、負極１０の各面１ｃ，１ｃを電解液に接するように用いることができる。更に本実施形態の負極１０は、図１に示す負極１と同様に集電用の厚膜導電体を有していない。これらの理由によって本実施形態の負極１０は、負極全体に占める活物質の割合が相対的に高くなり、単位重量当たり及び単位体積当たりのエネルギー密度を高めることができる。   As is clear from FIG. 3, in the negative electrode 10 of this embodiment, the active material layers 2 and 3 are exposed on the surfaces 1c and 1c of the negative electrode 10, so that the surfaces 1c and 1c of the negative electrode 10 are in contact with the electrolytic solution. Can be used. Further, the negative electrode 10 of the present embodiment does not have a thick film conductor for collecting current, like the negative electrode 1 shown in FIG. For these reasons, in the negative electrode 10 of the present embodiment, the ratio of the active material in the entire negative electrode is relatively high, and the energy density per unit weight and per unit volume can be increased.

エネルギー密度を高める観点から中間層６の厚みも小さいことが好ましい。具体的には、中間層６の厚みは、負極前駆体１０における被覆層３の厚みの２倍前後となっており、１〜１５μｍ、特に３〜１０μｍであることが好ましい。同様の理由により、負極１０全体の厚みは１０〜５０μｍ、特に１５〜３０μｍであることが好ましい。   From the viewpoint of increasing the energy density, the thickness of the intermediate layer 6 is also preferably small. Specifically, the thickness of the intermediate layer 6 is about twice the thickness of the coating layer 3 in the negative electrode precursor 10, and is preferably 1 to 15 μm, particularly preferably 3 to 10 μm. For the same reason, the thickness of the entire negative electrode 10 is preferably 10 to 50 μm, particularly preferably 15 to 30 μm.

本発明は前記実施形態に制限されない。例えば図１に示す実施形態においては、活物質層２の一面にのみ被覆層３が形成されたいたが、これに代えて活物質層の両面に被覆層を形成してもよい。この場合には、両被覆層に非水電解液が流通し得る程度の微細空隙を多数設け、電解液が活物質層へ到達するようにする。被覆層に微細空隙を形成するには、例えば微細空隙が形成されるようなめっき条件下に被覆層を電解めっきによって形成すればよい。或いは所定の薄膜形成手段を用いて被覆層を形成した後に負極１を圧延加工して、被覆層に多数の亀裂を形成させて微細空隙を形成すればよい。   The present invention is not limited to the embodiment. For example, in the embodiment shown in FIG. 1, the coating layer 3 is formed only on one surface of the active material layer 2, but instead, a coating layer may be formed on both surfaces of the active material layer. In this case, both coating layers are provided with a number of fine voids that allow the non-aqueous electrolyte to circulate so that the electrolyte reaches the active material layer. In order to form fine voids in the coating layer, for example, the coating layer may be formed by electrolytic plating under plating conditions that form fine voids. Alternatively, after forming the coating layer using a predetermined thin film forming means, the negative electrode 1 may be rolled to form a large number of cracks in the coating layer to form fine voids.

本発明の負極の一実施形態の断面構造を示す模式図である。It is a schematic diagram which shows the cross-section of one Embodiment of the negative electrode of this invention. 図１に示す負極の製造方法を模式的に示す工程図である。It is process drawing which shows typically the manufacturing method of the negative electrode shown in FIG. 本発明の負極の別の実施形態の断面構造を示す模式図である。It is a schematic diagram which shows the cross-section of another embodiment of the negative electrode of this invention.

符号の説明Explanation of symbols

１ 負極
２ 活物質層
３ 被覆層
４ 活物質粒子
５ 導電性粉末
６ 中間層
１０ 負極
１１ キャリア箔
DESCRIPTION OF SYMBOLS 1 Negative electrode 2 Active material layer 3 Coating layer 4 Active material particle 5 Conductive powder 6 Intermediate | middle layer 10 Negative electrode 11 Carrier foil

Claims (6)

キャリア箔の一面に、リチウム化合物の形成能の高い物質を含む活物質の粒子をバインダーで固定化して活物質層を形成し、An active material layer is formed on one surface of the carrier foil by immobilizing active material particles containing a material capable of forming a lithium compound with a binder.
該活物質層を該キャリア箔ごと非酸化性雰囲気下に焼結処理に付し、The active material layer is subjected to a sintering treatment together with the carrier foil in a non-oxidizing atmosphere,
該活物質層の表面に、薄膜形成手段によってリチウム化合物の形成能の低い物質からなる導電性の被覆層を形成し、次いでOn the surface of the active material layer, a conductive coating layer made of a material having a low lithium compound forming ability is formed by a thin film forming means, and then
該活物質層を該被覆層と共に該キャリア箔から剥離することを特徴とする非水電解液二次電池用負極の製造方法。A method for producing a negative electrode for a non-aqueous electrolyte secondary battery, wherein the active material layer is peeled from the carrier foil together with the coating layer. 焼結後にバインダーが残存するように焼結処理に付す請求項１記載の製造方法。The manufacturing method according to claim 1, wherein the sintering treatment is performed so that the binder remains after the sintering. 焼結処理に付す前の活物質層をキャリア箔と共に圧延する請求項１又は２記載の製造方法。The manufacturing method of Claim 1 or 2 which rolls the active material layer before attaching | subjecting a sintering process with carrier foil. 薄膜形成手段が電解めっき、無電解めっき、スパッタリング法、物理気相蒸着法、化学気相蒸着法又はダイレクトメタレーション法である請求項１ないし３のいずれかに記載の製造方法。The manufacturing method according to any one of claims 1 to 3, wherein the thin film forming means is electrolytic plating, electroless plating, sputtering, physical vapor deposition, chemical vapor deposition, or direct metallation. キャリア箔として圧延で製造されたものを用いる請求項１ないし４のいずれかに記載の製造方法。The manufacturing method in any one of Claim 1 thru | or 4 using what was manufactured by rolling as carrier foil. キャリア箔として電解で製造されたものを用い、その光沢面上に活物質層を形成する請求項１ないし４のいずれかに記載の製造方法。The production method according to any one of claims 1 to 4, wherein an active material layer is formed on the glossy surface of the carrier foil produced by electrolysis.
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JPH10270086A (en) * 1997-03-26 1998-10-09 Seiko Instr Inc Nonaqueous electrolyte secondary battery
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