WO2013161733A1 - Negative electrode active material for a lithium secondary battery and method for manufacturing same - Google Patents

Negative electrode active material for a lithium secondary battery and method for manufacturing same Download PDF

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Publication number
WO2013161733A1
WO2013161733A1 PCT/JP2013/061726 JP2013061726W WO2013161733A1 WO 2013161733 A1 WO2013161733 A1 WO 2013161733A1 JP 2013061726 W JP2013061726 W JP 2013061726W WO 2013161733 A1 WO2013161733 A1 WO 2013161733A1
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negative electrode
lithium secondary
etching
active material
electrode active
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PCT/JP2013/061726
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French (fr)
Japanese (ja)
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晃二 久幸
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昭和電工株式会社
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Priority to CN201380005560.XA priority Critical patent/CN104054197A/en
Publication of WO2013161733A1 publication Critical patent/WO2013161733A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/46—Alloys based on magnesium or aluminium
    • H01M4/463—Aluminium based
    • 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

Definitions

  • a negative electrode of such a lithium secondary battery conventionally, those formed from various carbon materials such as graphite and carbon having a low crystallinity have been widely used.
  • a negative electrode made of a carbon material has a low usable current density and an insufficient theoretical capacity.
  • graphite which is one of the carbon materials, has a theoretical capacity of only 372 mAh / g, and therefore a higher capacity is desired.
  • a negative electrode active material made of a material other than metal Li which is a substance having a discharge capacity larger than that of a general-purpose carbon material.
  • elements such as Sn, Si and Ag, nitrides, oxides and the like of these can occlude Li ions to form an alloy with Li ions, and the occlusion amount is much larger than various carbon materials. It is known to show a value.
  • a negative electrode active material is an alloy of two or more phases composed of a metal that easily stores and releases Li ions and a metal that does not store and release, and the metal that does not store and release does not store and release Li ions.
  • a negative electrode active material intended to suppress the expansion / contraction of the negative electrode during discharge and the cracking or pulverization of the negative electrode due to expansion / contraction has been proposed.
  • Patent Document 1 discloses a raw material melt consisting of a Li ion storage phase ⁇ and a phase ⁇ made of an intermetallic compound or a solid solution of an element constituting the Li ion storage phase ⁇ and another element and having a selected composition.
  • An anode active material having a structure rapidly quenched and solidified by an atomizing method, a roll quenching method, or the like is described.
  • Patent Document 2 discloses Ag, Al, Au, Ca, Cu, Fe, In, Mg, Pd, Pt, Y Zn, Ti, V, Cr, Mn, Co, Ni, Y, Zr, Nb, Mo, Hf, Ta, W and an A component that is at least one element selected from the group consisting of rare earth elements, and Ga, A negative electrode made of a composite powder formed by mixing a raw material consisting of a B component, which is at least one element selected from the group consisting of Ge, Sb, Si and Sn, and performing mechanical alloying treatment Substances have been described.
  • the object of the present invention is to solve the above-described problems, and to increase the amount of occlusion / release of Li ions, thus increasing the charge / discharge capacity and reducing the capacity decrease due to repeated charge / discharge.
  • An object of the present invention is to provide a negative electrode active material for a lithium secondary battery and a method for producing the same, which can achieve a longer cycle life.
  • the present invention comprises the following aspects in order to achieve the above object.
  • a negative electrode active material for a lithium secondary battery comprising the prepared powder.
  • the powder formed by cutting the etching foil contains particles having a plurality of holes that are open on the surface and have a hole diameter of 0.5 ⁇ m or more.
  • the particle size of all particles is 5 to 150 ⁇ m
  • the pore size of the particles having pores is 0.5 to 15 ⁇ m
  • the ratio of the pore size to the particle size (pore size / particle size) of the particles having pores is 0.
  • the etching foil has a thickness of 200 ⁇ m or less, the hole diameter of the etching holes in both porous layers is 0.5 to 15 ⁇ m, and the total opening area of all the etching holes in both porous layers is the surface area of both surfaces of the etching foil.
  • a lithium secondary battery comprising the negative electrode described in 10) above, a separator, and a positive electrode for a lithium secondary battery.
  • the reason is estimated as follows. That is, in the lithium secondary battery including the negative electrode formed from the negative electrode active materials 1) to 5) above, Li ions enter the pores of the particles during charging, and a compound containing Li ions is formed in the pores. In addition, a compound containing Li ions is formed in the gap formed between the particles of the powder of the negative electrode active material, and the expansion of the negative electrode active material during charging can be suppressed. Further, the shrinkage of the negative electrode active material when Li ions exit from the negative electrode active material during discharge is reduced. As a result, it is estimated that the volume change of the negative electrode active material during charging / discharging is reduced.
  • the lithium secondary battery including the negative electrode formed from the negative electrode active materials 1) to 5) described above is compared with the lithium secondary battery including the negative electrode formed from the negative electrode active material formed of various carbon materials.
  • a large amount of Li ions can be occluded / released, and the charge / discharge capacity is increased.
  • the volume change at the time of charging / discharging of the lithium secondary battery using the negative electrode formed from the negative electrode active material is further effectively reduced. be able to.
  • an etching foil having an Fe content of 0.05% by mass or less and made by etching both surfaces of a foil mainly composed of Al and having a porous layer on both surfaces is cut. Therefore, the negative electrode active material for a lithium secondary battery can be easily manufactured.
  • the negative electrode active materials 2) to 4) can be easily produced.
  • FIG. 1 shows particles constituting the negative electrode active material for a lithium secondary battery according to the present invention
  • FIG. 2 shows pores formed in the particles of the negative electrode active material for the lithium secondary battery of FIG. 3 shows an apparatus for cutting the etching foil to form a powder that becomes the negative electrode active material for the lithium secondary battery of FIG. 1
  • FIG. 4 is formed using the negative electrode active material for the lithium secondary battery of FIG. 1 shows an example of a lithium secondary battery having a negative electrode formed.
  • a negative electrode active material for a lithium secondary battery is a step of etching an both sides of a foil having an Fe content of 0.05% by mass or less and having Al as a main component to form an etching foil, and a step of cutting the etching foil Are formed in this order.
  • foil means that the thickness is 0.006 to 0.2 mm as defined in JIS.
  • Powder means an aggregate of particles having a maximum dimension of 1 mm or less, as defined in JIS Z2500.
  • the powder constituting the negative electrode active material for a lithium secondary battery includes particles having various shapes. As shown in FIG. 1, a plurality of pores (2) that are open on the surface and have a pore diameter of 0.5 ⁇ m or more. It is preferable that particles (1) having) are contained. This is because if the pore diameter is less than 0.5 ⁇ m, Li ions cannot penetrate into the inside of the pores (2), and the occlusion amount of Li ions may be reduced.
  • the upper limit of the pore diameter of the pores (2) of the particles (1) is preferably 15 ⁇ m. In order to make the hole diameter of the hole (2) exceed 15 ⁇ m, it is necessary to make the particle diameter of the particle (1) larger than 150 ⁇ m.
  • the total opening area of all the pores (2) to the surface of the particles (1) in each particle (1) having the pores (2) is 10% or more of the surface area of each particle (1) having the pores (2). It is preferable that When the total area of the openings of all the pores (2) to the surface of the particles (1) is less than 10% of the surface area of each particle (1) having the pores (2), they enter the pores (2). This is because the amount of occlusion of Li ions may be reduced. In particles having a plurality of holes (2), at least some of the holes (2A) may be through-holes.
  • the particle diameter of all the particles (1) is preferably 5 to 150 ⁇ m.
  • the particle diameter exceeds 150 ⁇ m when mixed with a conductive additive and a binder in producing a negative electrode, it does not form an appropriate paste, and coating on the current collector may be difficult.
  • the particles (1) having the pores (2) if the particle size of the particles (1) is less than 5 ⁇ m, the pores (2) having a pore size of 0.5 ⁇ m or more cannot be formed.
  • the ratio of pore diameter to particle diameter is preferably less than 0.1.
  • the powder which comprises the negative electrode active material for lithium secondary batteries may contain the particle
  • the charge / discharge was limited to the etching foil used to form the negative electrode active material, which had an Fe content of 0.05% by mass or less and was etched on both sides of the foil containing Al as a main component. This is because sometimes it is possible to prevent a short circuit when Li is preferentially deposited on Fe, and to increase the amount of occlusion / release of Li ions to the negative electrode made of the formed negative electrode active material.
  • the purity of the foil whose Fe content is 0.05% by mass or less and whose main component is Al is preferably 90% by mass or more. In this case, the initial charge / discharge capacity of the lithium secondary battery using the negative electrode formed of the negative electrode active material can be increased, and a decrease in capacity due to repeated charge / discharge can be reduced.
  • the etching foil used to form the negative electrode active material is etched on both sides, a porous layer is formed on both sides, but the etching foil is formed on the porous layer of the etching foil.
  • the hole diameter of the etching holes is preferably 0.5 to 15 ⁇ m, and more preferably 0.5 to 5 ⁇ m.
  • the term “hole diameter” means that the area of the etching hole is equal to this area.
  • a plurality of etching holes may be bonded.
  • the area of each bonded etching hole is equivalent to a circle represented by the diameter of a circle equal to this area.
  • the diameter is referred to as the hole diameter.
  • the depth of the etching hole of etching foil is not specifically limited, It is preferable that at least one part etching hole of all the etching holes is a through-hole which penetrated etching foil. Moreover, it is preferable that the sum total of the opening area to the etching foil surface of all the etching holes is 10% or more of the surface area of both surfaces of the etching foil on both surfaces of the etching foil.
  • Conditions such as the hole diameter of the etching hole of the etching foil and the ratio of the total opening area of all the etching holes to the surface area of the etching foil depend on the condition of the Li ions into the pores of the powder particles formed by cutting the etching foil. It is determined from the viewpoint of absorbing the occlusion amount, the expansion of the negative electrode during charging of the lithium secondary battery including the negative electrode made of the negative electrode active material, and the contraction of the negative electrode during discharge.
  • an etching foil for example, a material satisfying the above-mentioned conditions can be used from those commercially available as an electrode foil for an aluminum electrolytic capacitor.
  • an etching foil for an aluminum electrolytic capacitor is formed with an anodized film corresponding to the operating voltage, but the hole diameter is determined so that the hole is not crushed by this anodized film.
  • the etching foil for use does not satisfy the conditions such as the hole diameter of the etching foil forming the negative electrode active material of the present invention having different purposes of use and the opening area of the etching hole.
  • the same conditions as the etching foil for forming the powder that is the negative electrode active material of the present invention, that is, the thickness, the hole diameter of the etching hole, and the etching foil surface of all the etching holes There are those having a ratio of the total opening area to the surface area of the etching foil.
  • the etching foil used to form the negative electrode active material is, for example, an Al foil having a purity of 90% by mass or more, preferably an Al foil having a purity of 99.9% by mass or more, and an Fe content of 0.05% by mass. 2% or less of hydrochloric acid on both surfaces of an Al foil in which 70% or more, preferably 90% or more, and desirably 95% or more of the crystal grains having (100) faces out of all the crystal grains are present.
  • the foil surface is dissolved during etching, and it becomes difficult to form a desired etching hole.
  • the higher the purity of the Al foil used the better.
  • the ratio of the crystal grains having the (100) face is low in the total crystal grains of the Al foil used to produce the etching foil, the foil surface dissolves during etching and desired etching holes are formed. Therefore, as described above, it is desirable that the ratio of the crystal grains having the (100) plane is higher among all the crystal grains of the Al foil.
  • the etching is not limited to direct current etching, and may be alternating current etching or chemical etching, or at least two of these three types of etching are appropriately performed. You may carry out combining in order.
  • etching foil used for forming the negative electrode active material it is preferable to use an unformed foil whose surface is not subjected to a chemical conversion treatment.
  • a method of cutting finely with a blade is preferable, and the method of tearing or knocking may cause the opening to the particle surface of the formed powder to be crushed Therefore, it is not preferable.
  • a method of finely cutting using a blade there is a method of using an apparatus including a movable blade and a fixed blade, rotating the movable blade at a high speed, and cutting with the fixed blade.
  • a screen having a large number of sieves is arranged below the movable blade and the fixed blade, and by adjusting the size of the sieve appropriately, among the particles of the powder formed by cutting the etching foil,
  • the size of the particles that have passed through the sieve can be 5 to 150 ⁇ m.
  • FIG. 3 schematically shows a specific example of an apparatus for cutting an etching foil.
  • the housing (21) of the cutting device (20) is provided with a cutting chamber (22) and a powder recovery chamber (23) located below the cutting chamber (22).
  • the housing (21) is provided with an etching foil inlet (24) facing the cutting chamber (22) and a powder recovery port (25) facing the powder recovery chamber (23). It can be freely opened and closed by means of lids (26) and (27) which are detachably attached to.
  • a screen (32) having a plurality of sieves is arranged between the cutting chamber (22) and the powder recovery chamber (23) in the housing (21) of the cutting device (20).
  • the opening of the screen (32) is adjusted so that only particles having a particle size of 150 ⁇ m or less can pass through.
  • the negative electrode (12) is obtained by adhering a mixture (16) containing a negative electrode active material, a conductive additive and a binder on a current collector (15).
  • a current collector for example, a rolled copper foil or a copper foil such as an electrolytic copper foil is used.
  • a conductive auxiliary agent ketjen black or acetylene black is used, but it is not limited to this.
  • the binder polyvinylidene fluoride is used, but is not limited thereto.

Abstract

This negative electrode material for a lithium secondary battery is formed from a powder formed by carrying out in order a step for creating an etched foil by etching both surfaces of a foil that has a Fe content of 0.05% by mass or less and Al as a main component and a step for cutting that etched foil. This powder includes particles (1) that have holes (2) that are opened in the surface of the particles and have a hole diameter of 0.5 µm or greater. The total of the opening surface area for all of the holes (2) in the surface of a particle (1) in the particles (1) having the holes (2) is 10% or greater of the surface area of the particle having the holes (2). With the use of this negative electrode material (1) for a lithium secondary battery, increased life for cycle life of the lithium secondary battery can be achieved.

Description

リチウム二次電池用負極活物質およびその製造方法Negative electrode active material for lithium secondary battery and method for producing the same
　この発明はリチウム二次電池用負極活物質およびその製造方法に関し、さらに詳しくは、Ｌｉイオンを多量にかつ可逆的に吸蔵・放出することのできる非水電解質二次電池用負極活物質およびその製造方法に関する。ここで、非水電解質二次電池は、電解質を有機溶媒に溶解した非水電解質を用いた二次電池と、高分子電解質やゲル電解質などの非水電解質を用いた二次電池とを包含する。 The present invention relates to a negative electrode active material for a lithium secondary battery and a method for producing the same, and more specifically, a negative electrode active material for a non-aqueous electrolyte secondary battery capable of reversibly occluding and releasing Li ions in large quantities and the production thereof. Regarding the method. Here, the nonaqueous electrolyte secondary battery includes a secondary battery using a nonaqueous electrolyte obtained by dissolving an electrolyte in an organic solvent, and a secondary battery using a nonaqueous electrolyte such as a polymer electrolyte or a gel electrolyte. .
　リチウムイオン電池、リチウムポリマー電池などのリチウム二次電池は、高いエネルギー密度を有するものであり、移動体通信機器や携帯用電子機器などの主電源として利用されるにとどまらず、大型の電力貯蔵用電源や車載用電源としても注目されている。 Lithium secondary batteries such as lithium ion batteries and lithium polymer batteries have a high energy density and are not only used as main power sources for mobile communication devices and portable electronic devices, but also for large-scale power storage. It is also attracting attention as a power source and an on-vehicle power source.
　このようなリチウム二次電池の負極としては、従来、黒鉛、結晶化度の低い炭素等の各種炭素材料から形成されたものが広く用いられていた。しかしながら、炭素材料からなる負極は、使用可能な電流密度が低く、理論容量も不十分である。たとえば炭素材料のひとつである黒鉛は、理論容量が３７２ｍＡｈ／ｇに過ぎないため、より一層の高容量化が望まれている。 As a negative electrode of such a lithium secondary battery, conventionally, those formed from various carbon materials such as graphite and carbon having a low crystallinity have been widely used. However, a negative electrode made of a carbon material has a low usable current density and an insufficient theoretical capacity. For example, graphite, which is one of the carbon materials, has a theoretical capacity of only 372 mAh / g, and therefore a higher capacity is desired.
　一方、金属Ｌｉから形成された負極をリチウム二次電池に用いた場合には、高い理論容量が得られることが知られているが、充電時に、金属Ｌｉが負極にデンドライト状に析出し、充放電を繰り返すことによって成長を続け、正極側に達して内部短絡が起こるというという大きな欠点がある。その上、析出したデンドライト状金属Ｌｉは、比表面積が大きいために反応活性度が高く、その表面で電子伝導性のない溶媒の分解生成物からなる界面被膜が形成され、これによって電池の内部抵抗が高くなって充放電効率が低下する。このような理由により、金属Ｌｉから形成された負極を用いるリチウム二次電池は信頼性が低く、サイクル寿命が短いという欠点があり、広く実用化される段階には達していない。 On the other hand, when a negative electrode formed from metallic Li is used for a lithium secondary battery, it is known that a high theoretical capacity can be obtained. However, during charging, metallic Li precipitates on the negative electrode in a dendrite-like manner, and is charged. There is a major drawback in that the growth continues by repeating the discharge and reaches the positive electrode side to cause an internal short circuit. In addition, the deposited dendritic metal Li has a high specific activity, and thus has a high reaction activity, and an interfacial film made of a decomposition product of a solvent having no electron conductivity is formed on the surface, thereby forming an internal resistance of the battery. As a result, the charge / discharge efficiency decreases. For these reasons, lithium secondary batteries using a negative electrode formed from metal Li have the disadvantages of low reliability and short cycle life, and have not yet reached the stage of wide practical use.
　このような背景から、汎用の炭素材料よりも放電容量の大きい物質であって、金属Ｌｉ以外の材料からなる負極活物質が望まれている。例えば、Ｓｎ、Ｓｉ、Ａｇなどの元素や、これらの窒化物、酸化物等は、Ｌｉイオンを吸蔵してＬｉイオンと合金を形成することができ、その吸蔵量は各種炭素材料よりはるかに大きい値を示すことが知られている。 From such a background, a negative electrode active material made of a material other than metal Li, which is a substance having a discharge capacity larger than that of a general-purpose carbon material, is desired. For example, elements such as Sn, Si and Ag, nitrides, oxides and the like of these can occlude Li ions to form an alloy with Li ions, and the occlusion amount is much larger than various carbon materials. It is known to show a value.
　しかしながら、Ｓｎ、Ｓｉ、Ａｇなどの元素や、これらの窒化物、酸化物等から形成された負極をリチウム二次電池に用いる場合には、充放電のサイクルを繰り返すうちに、Ｌｉイオンの吸蔵・放出に伴って負極に大きな膨張・収縮が発生し、この膨張・収縮に起因して負極の割れや微粉化が発生する。したがって、Ｓｎ、Ｓｉ、Ａｇなどの元素や、これらの窒化物、酸化物等上記物質から形成された負極を用いるリチウム二次電池はサイクル寿命が低下することになって実用電池として用いることはできない。 However, when a negative electrode formed from an element such as Sn, Si, or Ag, or a nitride or oxide thereof is used for a lithium secondary battery, the Li-ion occlusion / Along with the release, the negative electrode is greatly expanded / contracted, and the negative electrode is cracked or pulverized due to the expansion / contraction. Therefore, a lithium secondary battery using a negative electrode formed from the above-described substances such as Sn, Si, Ag, etc., and their nitrides and oxides cannot be used as a practical battery because its cycle life is reduced. .
　その対策として、Ｌｉイオンを吸蔵・放出しやすい金属と、吸蔵・放出を行なわない金属とからなる２相以上の合金を負極活物質とし、吸蔵・放出を行なわない金属によって、Ｌｉイオンを吸蔵・放出する際の負極の膨張・収縮、および膨張・収縮に起因する負極の割れや微粉化を抑制することを意図した負極活物質が提案されている。 As a countermeasure, a negative electrode active material is an alloy of two or more phases composed of a metal that easily stores and releases Li ions and a metal that does not store and release, and the metal that does not store and release does not store and release Li ions. A negative electrode active material intended to suppress the expansion / contraction of the negative electrode during discharge and the cracking or pulverization of the negative electrode due to expansion / contraction has been proposed.
　たとえば特許文献１には、Ｌｉイオン吸蔵相α 、およびＬｉイオン吸蔵相αを構成する元素と他の元素との金属間化合物または固溶体からなる相βよりなり、かつ組成を選択した原料の溶湯を、アトマイズ法、ロール急冷法等により急冷凝固させた組織を有する負極活物質が記載され、特許文献２には、Ａｇ、Ａｌ、Ａｕ、Ｃａ、Ｃｕ、Ｆｅ、Ｉｎ、Ｍｇ、Ｐｄ、Ｐｔ、Ｙ、Ｚｎ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｃｏ、Ｎｉ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｈｆ、Ｔａ、Ｗおよび希土類元素からなる群から選ばれた少なくとも一種の元素であるＡ成分、ならびにＧａ、Ｇｅ、Ｓｂ、Ｓｉ及びＳｎからなる群から選ばれた少なくとも一種の元素であるＢ成分からなる原料物質を混合し、メカニカルアロイング処理を行って形成された複合粉末からなる負極活物質が記載されている。 For example, Patent Document 1 discloses a raw material melt consisting of a Li ion storage phase α and a phase β made of an intermetallic compound or a solid solution of an element constituting the Li ion storage phase α and another element and having a selected composition. , An anode active material having a structure rapidly quenched and solidified by an atomizing method, a roll quenching method, or the like is described. Patent Document 2 discloses Ag, Al, Au, Ca, Cu, Fe, In, Mg, Pd, Pt, Y Zn, Ti, V, Cr, Mn, Co, Ni, Y, Zr, Nb, Mo, Hf, Ta, W and an A component that is at least one element selected from the group consisting of rare earth elements, and Ga, A negative electrode made of a composite powder formed by mixing a raw material consisting of a B component, which is at least one element selected from the group consisting of Ge, Sb, Si and Sn, and performing mechanical alloying treatment Substances have been described.
　しかしながら、特許文献１および２記載の負極活物質から形成された負極においては、大きな初期放電容量が得られるものの、充放電を繰り返すうちに生じる負極の膨張・収縮、および膨張・収縮に起因する負極の割れや微粉化を効果的に抑制することはできず、サイクル寿命の長寿命化を達成するには至っていない。 However, in the negative electrode formed from the negative electrode active material described in Patent Documents 1 and 2, a large initial discharge capacity is obtained, but the negative electrode is caused by expansion / contraction of the negative electrode and the expansion / contraction caused by repeated charge / discharge. Cracking and pulverization cannot be effectively suppressed, and the cycle life has not been extended.
特開２００１－２９７７５７号公報JP 2001-297757 A 特開２００５－７８９９９号公報JP 2005-78999 A
　この発明の目的は、上記問題を解決し、Ｌｉイオンを吸蔵・放出する量が多く、したがって充電・放電容量が大きくなるとともに、充電・放電を繰り返すことによる容量低下が少なく、リチウム二次電池のサイクル寿命の長寿命化を達成することができるリチウム二次電池用負極活物質およびその製造方法を提供することにある。 The object of the present invention is to solve the above-described problems, and to increase the amount of occlusion / release of Li ions, thus increasing the charge / discharge capacity and reducing the capacity decrease due to repeated charge / discharge. An object of the present invention is to provide a negative electrode active material for a lithium secondary battery and a method for producing the same, which can achieve a longer cycle life.
　本発明は、上記目的を達成するために以下の態様からなる。 The present invention comprises the following aspects in order to achieve the above object.
　1)Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングしてエッチング箔をつくる工程、および当該エッチング箔を切断する工程をこの順序で行うことにより形成された粉末からなるリチウム二次電池用負極活物質。 1) Formed by performing in this order the steps of etching the both sides of a foil containing Fe as a main component with an Fe content of 0.05% by mass or less and cutting the etching foil. A negative electrode active material for a lithium secondary battery comprising the prepared powder.
　2)Ａｌを主成分とする箔のＡｌ純度が９０質量％以上である上記1)記載のリチウム二次電池用負極活物質。 2) The negative electrode active material for lithium secondary batteries according to 1) above, wherein the Al purity of the foil mainly composed of Al is 90% by mass or more.
　3)エッチング箔を切断して形成された粉末中に、表面に開口しかつ孔径が０．５μｍ以上である複数の孔を有する粒子が含まれており、孔を有する粒子におけるすべての孔の粒子表面への開口面積の合計が、当該孔を有する各粒子の表面積の１０％以上である上記1)または2)記載のリチウム二次電池用負極活物質。 3) The powder formed by cutting the etching foil contains particles having a plurality of holes that are open on the surface and have a hole diameter of 0.5 μm or more. The negative electrode active material for a lithium secondary battery according to the above 1) or 2), wherein the total opening area to the surface is 10% or more of the surface area of each particle having the pores.
　4)すべての粒子の粒径が５～１５０μｍであり、孔を有する粒子の孔径が０．５～１５μｍであり、孔を有する粒子における粒径に対する孔径の比（孔径／粒径）が０．１未満である上記3)記載のリチウム二次電池用負極活物質。 4) The particle size of all particles is 5 to 150 μm, the pore size of the particles having pores is 0.5 to 15 μm, and the ratio of the pore size to the particle size (pore size / particle size) of the particles having pores is 0. The negative electrode active material for lithium secondary batteries according to 3) above, which is less than 1.
　5)エッチング箔に形成されたすべてのエッチング孔のうち少なくとも一部のエッチング孔が貫通孔である上記1)～4)のうちのいずれかに記載のリチウム二次電池用負極活物質。 5) The negative electrode active material for a lithium secondary battery according to any one of 1) to 4) above, wherein at least some of the etching holes formed in the etching foil are through holes.
　6)Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングすることによりつくられかつ両面に多孔質層を有するエッチング箔を、切断して粉末とすることを特徴とするリチウム二次電池用負極活物質の製造方法。 6) Cutting an etching foil having a Fe content of 0.05% by mass or less and etching both surfaces of a foil containing Al as a main component and having a porous layer on both surfaces into a powder. A method for producing a negative electrode active material for a lithium secondary battery.
　7)Ａｌを主成分とする箔のＡｌ純度が９０質量％以上である上記6)記載のリチウム二次電池用負極活物質の製造方法。 7) The method for producing a negative electrode active material for a lithium secondary battery according to 6) above, wherein the Al purity of the foil mainly composed of Al is 90% by mass or more.
　8)エッチング箔として、厚みが２００μｍ以下、両多孔質層におけるエッチング孔の孔径が０．５～１５μｍ、両多孔質層におけるすべてのエッチング孔の開口面積の合計が、それぞれエッチング箔の両面の表面積の１０％以上であり、すべてのエッチング孔のうちの少なくとも一部のエッチング孔が貫通孔となっているものを用いる上記6)または7)記載のリチウム二次電池用負極活物質の製造方法。 8) The etching foil has a thickness of 200 μm or less, the hole diameter of the etching holes in both porous layers is 0.5 to 15 μm, and the total opening area of all the etching holes in both porous layers is the surface area of both surfaces of the etching foil. The method for producing a negative electrode active material for a lithium secondary battery as described in 6) or 7) above, wherein at least some of the etching holes are through-holes.
　9)エッチング箔として、厚みが５０～１５０μｍであるものを用いる上記8)記載のリチウム二次電池用負極活物質の製造方法。 9) The method for producing a negative electrode active material for a lithium secondary battery according to 8) above, wherein an etching foil having a thickness of 50 to 150 μm is used.
　10)集電体上に、上記1)～5)のうちのいずれかに記載された負極活物質、導電助剤および結着剤を含む混合物質が付着されているリチウム二次電池用負極。 10) A negative electrode for a lithium secondary battery in which a mixed material containing a negative electrode active material, a conductive additive and a binder described in any one of 1) to 5) above is attached on a current collector.
　11)上記10)記載の負極と、セパレータと、リチウム二次電池用正極とを備えているリチウム二次電池。 11) A lithium secondary battery comprising the negative electrode described in 10) above, a separator, and a positive electrode for a lithium secondary battery.
　上記1)～5)のリチウム二次電池用負極活物質によれば、Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングしてエッチング箔をつくる工程、および当該エッチング箔を切断する工程をこの順序で行うことにより形成された粉末からなるので、エッチング箔を切断して形成された粉末中に、表面に開口した複数の孔を有する粒子が含まれる。したがって、充電・放電の際の負極活物質の体積変化が小さくなって、充電・放電の際の負極活物質の体積変化が大きくなることに起因する負極活物質の割れや微粉化、ならびに負極活物質の導電助剤および結着剤からの剥離を効果的に抑制することができるとともに、充電・放電を繰り返すことによる容量低下が少なくなってリチウム二次電池のサイクル寿命の長寿命化を図ることが可能になると考えられる。その理由は、次に述べるとおりであると推定される。すなわち、上記1)～5)の負極活物質から形成された負極を備えたリチウム二次電池においては、充電時にＬｉイオンが粒子の孔中に入り込んで孔内でＬｉイオンを含む化合物が形成されるとともに、負極活物質の粉末の粒子間に生じた隙間内に入り込んで隙間内でＬｉイオンを含む化合物が形成されることになり、充電時の負極活物質の膨張を抑制することができる。また、放電時にＬｉイオンが負極活物質から出る際の負極活物質の収縮も小さくなる。その結果、充電・放電の際の負極活物質の体積変化が小さくなると推定される。 According to the negative electrode active material for lithium secondary batteries of 1) to 5) above, a process for producing an etching foil by etching both surfaces of a foil having an Fe content of 0.05% by mass or less and containing Al as a main component And the powder formed by cutting the etching foil in this order, the powder formed by cutting the etching foil includes particles having a plurality of holes opened on the surface. . Accordingly, the volume change of the negative electrode active material during charging / discharging is reduced, and the volume change of the negative electrode active material during charging / discharging is increased. Separation of substances from conductive aids and binders can be effectively suppressed, and capacity reduction due to repeated charging and discharging is reduced, and the cycle life of lithium secondary batteries is extended. Will be possible. The reason is estimated as follows. That is, in the lithium secondary battery including the negative electrode formed from the negative electrode active materials 1) to 5) above, Li ions enter the pores of the particles during charging, and a compound containing Li ions is formed in the pores. In addition, a compound containing Li ions is formed in the gap formed between the particles of the powder of the negative electrode active material, and the expansion of the negative electrode active material during charging can be suppressed. Further, the shrinkage of the negative electrode active material when Li ions exit from the negative electrode active material during discharge is reduced. As a result, it is estimated that the volume change of the negative electrode active material during charging / discharging is reduced.
　また、エッチング箔のＦｅ含有量が０．０５質量％以下であるから、充放電時にＬｉがＦｅに優先的に析出した際の短絡を防ぐことができる。 Moreover, since the Fe content of the etching foil is 0.05% by mass or less, it is possible to prevent a short circuit when Li preferentially precipitates on Fe during charge and discharge.
　しかも、上記1)～5)の負極活物質から形成された負極を備えたリチウム二次電池においては、各種炭素材料からなる負極活物質から形成された負極を備えたリチウム二次電池に比べて、Ｌｉイオンを多量に吸蔵・放出することが可能になって充電・放電容量が大きくなる。 In addition, the lithium secondary battery including the negative electrode formed from the negative electrode active materials 1) to 5) described above is compared with the lithium secondary battery including the negative electrode formed from the negative electrode active material formed of various carbon materials. In addition, a large amount of Li ions can be occluded / released, and the charge / discharge capacity is increased.
　上記2)～5)のリチウム二次電池用負極活物質によれば、当該負極活物質から形成された負極を用いたリチウム二次電池の充電・放電時の体積変化を一層効果的に小さくすることができる。 According to the negative electrode active material for lithium secondary batteries of 2) to 5) above, the volume change at the time of charging / discharging of the lithium secondary battery using the negative electrode formed from the negative electrode active material is further effectively reduced. be able to.
　上記6)の方法によれば、Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングすることによりつくられかつ両面に多孔質層を有するエッチング箔を切断するだけであるので、リチウム二次電池用負極活物質を容易に製造することができる。 According to the above method 6), an etching foil having an Fe content of 0.05% by mass or less and made by etching both surfaces of a foil mainly composed of Al and having a porous layer on both surfaces is cut. Therefore, the negative electrode active material for a lithium secondary battery can be easily manufactured.
　上記7)～9)の方法によれば、上記2)～4)の負極活物質を容易に製造することができる。 According to the methods 7) to 9), the negative electrode active materials 2) to 4) can be easily produced.
　上記10)の負極および上記11)のリチウム二次電池によれば、上記1)～5)の負極活物質で述べたような顕著な効果を奏する。 According to the negative electrode of 10) and the lithium secondary battery of 11), there are remarkable effects as described in the negative electrode active materials of 1) to 5).
この発明によるリチウム二次電池用負極活物質の粒子を示す拡大斜視図である。It is an expansion perspective view which shows the particle | grains of the negative electrode active material for lithium secondary batteries by this invention. 図１のリチウム二次電池用負極活物質の粒子の孔径を説明する図である。It is a figure explaining the hole diameter of the particle | grains of the negative electrode active material for lithium secondary batteries of FIG. エッチング箔を切断してリチウム二次電池用負極活物質となる粉末を形成する装置を示す概略垂直断面図である。It is a general | schematic vertical sectional view which shows the apparatus which cut | disconnects etching foil and forms the powder used as the negative electrode active material for lithium secondary batteries. 図１のリチウム二次電池用負極活物質を用いて形成された負極を有するリチウム二次電池を示す一部切り欠き正面図である。It is a partially cutaway front view which shows the lithium secondary battery which has a negative electrode formed using the negative electrode active material for lithium secondary batteries of FIG.
(1)：粒子
(2)：孔
(10)：リチウム二次電池
(12)：負極
(13)：正極
(14)：セパレータ (1): Particle
(2): Hole
(10): Lithium secondary battery
(12): Negative electrode
(13): Positive electrode
(14): Separator
　以下、この発明の実施形態を、図面を参照して説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　図１はこの発明によるリチウム二次電池用負極活物質を構成する粒子を示し、図２は図１のリチウム二次電池用負極活物質の粒子に形成された孔を示す。また、図３はエッチング箔を切断して図１のリチウム二次電池用負極活物質となる粉末を形成する装置を示し、図４は図１のリチウム二次電池用負極活物質を用いて形成された負極を有するリチウム二次電池の一例を示す。 FIG. 1 shows particles constituting the negative electrode active material for a lithium secondary battery according to the present invention, and FIG. 2 shows pores formed in the particles of the negative electrode active material for the lithium secondary battery of FIG. 3 shows an apparatus for cutting the etching foil to form a powder that becomes the negative electrode active material for the lithium secondary battery of FIG. 1, and FIG. 4 is formed using the negative electrode active material for the lithium secondary battery of FIG. 1 shows an example of a lithium secondary battery having a negative electrode formed.
　リチウム二次電池用負極活物質は、Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングしてエッチング箔をつくる工程、および当該エッチング箔を切断する工程をこの順序で行うことにより形成された粉末からなる。ここで、「箔」とは、ＪＩＳで規定されているように、厚さが０．００６～０．２ｍｍのものを意味するものとする。また、「粉末」とは、JIS Ｚ２５００で規定されているように、最大寸法１ｍｍ以下の粒子の集合体を意味するものとする。 A negative electrode active material for a lithium secondary battery is a step of etching an both sides of a foil having an Fe content of 0.05% by mass or less and having Al as a main component to form an etching foil, and a step of cutting the etching foil Are formed in this order. Here, “foil” means that the thickness is 0.006 to 0.2 mm as defined in JIS. “Powder” means an aggregate of particles having a maximum dimension of 1 mm or less, as defined in JIS Z2500.
　リチウム二次電池用負極活物質を構成する粉末には、様々な形状の粒子が含まれるが、図１に示すように、表面に開口しかつ孔径が０．５μｍ以上である複数の孔(2)を有する粒子(1)が含まれていることが好ましい。孔径が０．５μｍ未満であると、Ｌｉイオンが孔(2)の内部まで侵入できず、Ｌｉイオンの吸蔵量が少なくなるおそれがあるからである。粒子(1)の孔(2)の孔径の上限は、１５μｍであることが好ましい。孔(2)の孔径を１５μｍを超えたものにするためには、粒子(1)の粒径を１５０μｍよりも大きくする必要があり、この場合、負極をつくるにあたって導電助剤および結着剤と混合した際に、適度なペースト状にならず、集電体へのコーティングが困難になるおそれがあるからである。孔(2)を有する各粒子(1)におけるすべての孔(2)の粒子(1)表面への開口面積の合計は、当該孔(2)を有する各粒子(1)の表面積の１０％以上であることが好ましい。すべての孔(2)の粒子(1)表面への開口面積の合計が、当該孔(2)を有する各粒子(1)の表面積の１０％未満であると、孔(2)内に侵入するＬｉイオンの吸蔵量が少なくなるおそれがあるからである。複数の孔(2)を有する粒子において、少なくとも一部の孔(2A)が貫通孔となっている場合がある。 The powder constituting the negative electrode active material for a lithium secondary battery includes particles having various shapes. As shown in FIG. 1, a plurality of pores (2) that are open on the surface and have a pore diameter of 0.5 μm or more. It is preferable that particles (1) having) are contained. This is because if the pore diameter is less than 0.5 μm, Li ions cannot penetrate into the inside of the pores (2), and the occlusion amount of Li ions may be reduced. The upper limit of the pore diameter of the pores (2) of the particles (1) is preferably 15 μm. In order to make the hole diameter of the hole (2) exceed 15 μm, it is necessary to make the particle diameter of the particle (1) larger than 150 μm. In this case, the conductive auxiliary agent and the binder This is because, when mixed, the paste does not become an appropriate paste and it may be difficult to coat the current collector. The total opening area of all the pores (2) to the surface of the particles (1) in each particle (1) having the pores (2) is 10% or more of the surface area of each particle (1) having the pores (2). It is preferable that When the total area of the openings of all the pores (2) to the surface of the particles (1) is less than 10% of the surface area of each particle (1) having the pores (2), they enter the pores (2). This is because the amount of occlusion of Li ions may be reduced. In particles having a plurality of holes (2), at least some of the holes (2A) may be through-holes.
　また、すべての粒子(1)の粒径は５～１５０μｍであることが好ましい。粒径が１５０μｍを超えると、負極をつくるにあたって導電助剤および結着剤と混合した際に、適度なペースト状にならず、集電体上へのコーティングが困難になるおそれがある。また、孔(2)を有する粒子(1)の場合、粒子(1)の粒径が５μｍ未満であると孔径が０．５μｍ以上の孔(2)を形成することができない。孔(2)を有する粒子(1)の場合、粒径に対する孔径の比（孔径／粒径）は０．１未満であることが好ましい。 Further, the particle diameter of all the particles (1) is preferably 5 to 150 μm. When the particle diameter exceeds 150 μm, when mixed with a conductive additive and a binder in producing a negative electrode, it does not form an appropriate paste, and coating on the current collector may be difficult. In the case of the particles (1) having the pores (2), if the particle size of the particles (1) is less than 5 μm, the pores (2) having a pore size of 0.5 μm or more cannot be formed. In the case of particles (1) having pores (2), the ratio of pore diameter to particle diameter (pore diameter / particle diameter) is preferably less than 0.1.
　ここで、孔(2)の粒子(1)表面への開口は円形でないことが多いので、「孔径」という語は、図２(a)に示すように、孔(2)の面積を、この面積と等しい円(C)の直径(D)で表した円相当径を意味するものとする。また、粒子によっては、複数の孔(2)が結合している場合もあるが、この場合は、図２(b)および(c)に示すように、結合した各孔(2)の面積を、この面積と等しい円(C)の直径(D)で表した円相当径を孔径というものとする。 Here, since the opening of the hole (2) to the particle (1) surface is often not circular, the term “hole diameter” means the area of the hole (2) as shown in FIG. It shall mean the equivalent circle diameter represented by the diameter (D) of a circle (C) equal to the area. In addition, depending on the particle, a plurality of holes (2) may be bonded. In this case, as shown in FIGS. 2 (b) and (c), the area of each bonded hole (2) is reduced. The equivalent circle diameter represented by the diameter (D) of the circle (C) equal to this area is referred to as the hole diameter.
　なお、リチウム二次電池用負極活物質を構成する粉末には、孔を持たない粒子が含まれていることもある。 In addition, the powder which comprises the negative electrode active material for lithium secondary batteries may contain the particle | grains which do not have a hole.
　負極活物質を形成するのに用いられるエッチング箔を、Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面にエッチングを施したものに限定したのは、充放電時にＬｉがＦｅに優先的に析出した際の短絡を防ぐことができるとともに、形成された負極活物質からなる負極へのＬｉイオンの吸蔵・放出量を多くするためである。特に、Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の純度は、９０質量％以上であることが好ましい。この場合、負極活物質で形成された負極を用いたリチウム二次電池の初期充放電容量を大きくすることができるとともに、充放電を繰り返すことによる容量低下を少なくすることができる。 The charge / discharge was limited to the etching foil used to form the negative electrode active material, which had an Fe content of 0.05% by mass or less and was etched on both sides of the foil containing Al as a main component. This is because sometimes it is possible to prevent a short circuit when Li is preferentially deposited on Fe, and to increase the amount of occlusion / release of Li ions to the negative electrode made of the formed negative electrode active material. In particular, the purity of the foil whose Fe content is 0.05% by mass or less and whose main component is Al is preferably 90% by mass or more. In this case, the initial charge / discharge capacity of the lithium secondary battery using the negative electrode formed of the negative electrode active material can be increased, and a decrease in capacity due to repeated charge / discharge can be reduced.
　また、負極活物質を形成するのに用いられるエッチング箔は、両面にエッチングが施されているので、両面に多孔質層が形成されることになるが、エッチング箔の多孔質層に形成されているエッチング孔の孔径は０．５～１５μｍであることが好ましく、０．５～５μｍであることが望ましい。ここで、エッチング箔表面へのエッチング孔の開口は円形でないことが多いので、上述した粒子(1)の場合と同様に、「孔径」という語は、エッチング孔の面積を、この面積と等しい円の直径で表した円相当径を意味するものとする。また、エッチング箔の多孔質層においては、複数のエッチング孔が結合している場合もあるが、この場合は、結合した各エッチング孔の面積を、この面積と等しい円の直径で表した円相当径を孔径というものとする。また、エッチング箔のエッチング孔の深さは、特に限定されるものではなく、すべてのエッチング孔のうちの少なくとも一部のエッチング孔はエッチング箔を貫通した貫通孔であることが好ましい。また、エッチング箔の両面において、すべてのエッチング孔のエッチング箔表面への開口面積の合計が、エッチング箔の両面の表面積の１０％以上であることが好ましい。エッチング箔がこれらの条件を満たしている場合に、これを切断して形成された粉末の粒子が、上述した条件を満たすことになる。さらに、エッチング箔の厚みは２００μｍ以下であることが好ましい。エッチング箔の厚みが２００μｍを超えると、切断が困難になる。エッチング箔の厚みは５０～１５０μｍであることがさらに好ましい。この場合、上述した粒径の粒子(1)の生産効率が優れたものになる。 In addition, since the etching foil used to form the negative electrode active material is etched on both sides, a porous layer is formed on both sides, but the etching foil is formed on the porous layer of the etching foil. The hole diameter of the etching holes is preferably 0.5 to 15 μm, and more preferably 0.5 to 5 μm. Here, since the opening of the etching hole to the etching foil surface is often not circular, as in the case of the particle (1) described above, the term “hole diameter” means that the area of the etching hole is equal to this area. The equivalent circle diameter represented by the diameter of. In the porous layer of the etching foil, a plurality of etching holes may be bonded. In this case, the area of each bonded etching hole is equivalent to a circle represented by the diameter of a circle equal to this area. The diameter is referred to as the hole diameter. Moreover, the depth of the etching hole of etching foil is not specifically limited, It is preferable that at least one part etching hole of all the etching holes is a through-hole which penetrated etching foil. Moreover, it is preferable that the sum total of the opening area to the etching foil surface of all the etching holes is 10% or more of the surface area of both surfaces of the etching foil on both surfaces of the etching foil. When the etching foil satisfies these conditions, the powder particles formed by cutting the etching foil satisfy the above-described conditions. Furthermore, the thickness of the etching foil is preferably 200 μm or less. When the thickness of the etching foil exceeds 200 μm, cutting becomes difficult. The thickness of the etching foil is more preferably 50 to 150 μm. In this case, the production efficiency of the particles (1) having the above-mentioned particle diameter is excellent.
　エッチング箔のエッチング孔の孔径や、すべてのエッチング孔の開口面積の合計のエッチング箔の表面積に対する比率などの条件は、エッチング箔を切断して形成された粉末の粒子の孔内へのＬｉイオンの吸蔵量や、当該負極活物質からなる負極を備えたリチウム二次電池の充電時の負極の膨張や、放電時の負極の収縮を吸収するという観点から定められたものである。 Conditions such as the hole diameter of the etching hole of the etching foil and the ratio of the total opening area of all the etching holes to the surface area of the etching foil depend on the condition of the Li ions into the pores of the powder particles formed by cutting the etching foil. It is determined from the viewpoint of absorbing the occlusion amount, the expansion of the negative electrode during charging of the lithium secondary battery including the negative electrode made of the negative electrode active material, and the contraction of the negative electrode during discharge.
　このようなエッチング箔としては、たとえばアルミニウム電解コンデンサ用電極箔として市販されているもののうちから、上述した条件を満たすものを用いることができる。すなわち、アルミニウム電解コンデンサ用のエッチング箔には、使用電圧に応じた陽極酸化皮膜が形成されるが、この陽極酸化皮膜によって孔が潰れないように孔径が定められているので、すべてのアルミニウム電解コンデンサ用エッチング箔が、使用目的が異なっている本発明の負極活物質を形成するエッチング箔の孔の孔径や、エッチング孔の開口面積などの条件を満たしているわけではない。しかしながら、アルミニウム電解コンデンサ用のエッチング箔の中には、本発明の負極活物質である粉末を形成するエッチング箔と同様の条件、すなわち厚み、エッチング孔の孔径、すべてのエッチング孔のエッチング箔表面への開口面積の合計のエッチング箔の表面積に対する比率を有するものが存在する。 As such an etching foil, for example, a material satisfying the above-mentioned conditions can be used from those commercially available as an electrode foil for an aluminum electrolytic capacitor. In other words, an etching foil for an aluminum electrolytic capacitor is formed with an anodized film corresponding to the operating voltage, but the hole diameter is determined so that the hole is not crushed by this anodized film. The etching foil for use does not satisfy the conditions such as the hole diameter of the etching foil forming the negative electrode active material of the present invention having different purposes of use and the opening area of the etching hole. However, in the etching foil for aluminum electrolytic capacitors, the same conditions as the etching foil for forming the powder that is the negative electrode active material of the present invention, that is, the thickness, the hole diameter of the etching hole, and the etching foil surface of all the etching holes There are those having a ratio of the total opening area to the surface area of the etching foil.
　また、負極活物質を形成するのに用いられるエッチング箔は、たとえば純度９０質量％以上のＡｌ箔、好ましくは純度９９．９質量％以上のＡｌ箔であり、かつＦｅ含有量が０．０５質量％以下の箔であって、かつ全結晶粒のうち（１００）面を有する結晶粒が７０％以上、好ましくは９０％以上、望ましくは９５％以上存在するＡｌ箔の両面に、塩酸２～１５質量％と、硫酸、蓚酸およびリン酸からなる群のうちの少なくとも１種の酸を０．０１～５質量％含む水溶液中で直流エッチングを行う第１エッチング処理工程と、ＮＨ４+またはＮａ+を含む水溶液中で表面酸化皮膜を電気化学的または化学的に形成する１回以上の中間処理工程と、塩化ナトリウム、塩化アンモニウム、塩化カリウム等のＣｌ-を含む中性塩のうち少なくとも１種の中性塩を０．１～１０質量％含む水溶液中で直流エッチングを行う第２エッチング処理工程とを含む方法によって、上述したエッチング孔の孔径や、すべてのエッチング孔のエッチング箔表面への開口面積の合計のエッチング箔の表面積に対する比率などの条件を満たすように作製してもよい。 The etching foil used to form the negative electrode active material is, for example, an Al foil having a purity of 90% by mass or more, preferably an Al foil having a purity of 99.9% by mass or more, and an Fe content of 0.05% by mass. 2% or less of hydrochloric acid on both surfaces of an Al foil in which 70% or more, preferably 90% or more, and desirably 95% or more of the crystal grains having (100) faces out of all the crystal grains are present. A first etching treatment step of performing direct current etching in an aqueous solution containing 0.01% by mass to 5% by mass of at least one acid selected from the group consisting of sulfuric acid, oxalic acid, and phosphoric acid, NH 4 + or Na + electrochemically or chemically one or more intermediate processing steps of forming a surface oxide film in an aqueous solution containing sodium chloride, ammonium chloride, Cl of potassium chloride - at least one kind of neutral salts comprising And a second etching treatment step in which direct etching is performed in an aqueous solution containing 0.1 to 10% by weight of a neutral salt, the hole diameter of the etching holes and the opening area of all the etching holes on the etching foil surface. It may be produced so as to satisfy the conditions such as the ratio of the total etching foil to the surface area.
　エッチング箔を作製するのに用いられるＡｌ箔の純度が低くＦｅ含有量が０．０５質量％を超える場合には、エッチング時に箔表面が溶解し、所望のエッチング孔が形成されにくくなるので、上述したように、用いるＡｌ箔の純度が高いほど望ましい。同様に、エッチング箔を作製するのに用いられるＡｌ箔の全結晶粒のうち(１００）面を有する結晶粒の比率が低い場合には、エッチング時に箔表面が溶解し、所望のエッチング孔が形成されにくくなるので、上述したように、Ａｌ箔の全結晶粒のうち（１００）面を有する結晶粒の比率が高い方が望ましい。 When the purity of the Al foil used for producing the etching foil is low and the Fe content exceeds 0.05 mass%, the foil surface is dissolved during etching, and it becomes difficult to form a desired etching hole. As described above, the higher the purity of the Al foil used, the better. Similarly, when the ratio of the crystal grains having the (100) face is low in the total crystal grains of the Al foil used to produce the etching foil, the foil surface dissolves during etching and desired etching holes are formed. Therefore, as described above, it is desirable that the ratio of the crystal grains having the (100) plane is higher among all the crystal grains of the Al foil.
　なお、上記において、Ａｌ箔の純度は、JIS Ｈ４１７０に規定されているように、１００質量％からＦｅ、ＳｉおよびＣｕの合計量を減じた残部を表すものである。 In the above, the purity of the Al foil represents the balance obtained by subtracting the total amount of Fe, Si and Cu from 100% by mass, as defined in JIS H4170.
　また、所定のエッチング孔が形成されるのであれば、直流エッチングに限定されるものではなく、交流エッチングや化学エッチングであってもよく、あるいはこれら３種類のエッチングのうち少なくとも２つのエッチングを適当な順序で組み合わせて行われてもよい。 Further, as long as a predetermined etching hole is formed, the etching is not limited to direct current etching, and may be alternating current etching or chemical etching, or at least two of these three types of etching are appropriately performed. You may carry out combining in order.
　なお、負極活物質を形成するのに用いられるエッチング箔としては、表面に化成処理が施されていない未化成箔を用いることが好ましい。 In addition, as an etching foil used for forming the negative electrode active material, it is preferable to use an unformed foil whose surface is not subjected to a chemical conversion treatment.
　エッチング箔を切断して粉末にする切断方法としては、刃を使って細かく切断する方法が好ましく、引きちぎったり、たたきつけたりする方法は、形成された粉末の粒子表面への開口が潰れる可能性があるので好ましくない。刃を使って細かく切断する方法としては、可動刃と固定刃とを備えた装置を使用し、可動刃を高速回転させて固定刃とともに切断する方法がある。この場合、可動刃および固定刃の下方に多数のふるい目を有するスクリーンを配置し、ふるいの大きさを適切に調節することにより、エッチング箔を切断することにより形成された粉末の粒子うちスクリーンのふるい目を通過した粒子の大きさを、５～１５０μｍにすることができる。 As the cutting method of cutting the etching foil into powder, a method of cutting finely with a blade is preferable, and the method of tearing or knocking may cause the opening to the particle surface of the formed powder to be crushed Therefore, it is not preferable. As a method of finely cutting using a blade, there is a method of using an apparatus including a movable blade and a fixed blade, rotating the movable blade at a high speed, and cutting with the fixed blade. In this case, a screen having a large number of sieves is arranged below the movable blade and the fixed blade, and by adjusting the size of the sieve appropriately, among the particles of the powder formed by cutting the etching foil, The size of the particles that have passed through the sieve can be 5 to 150 μm.
　図３は、エッチング箔を切断する装置の一具体例を概略的に示す。 FIG. 3 schematically shows a specific example of an apparatus for cutting an etching foil.
　切断装置(20)のハウジング(21)には、切断室(22)と、切断室(22)の下方に位置する粉末回収室(23)とが設けられている。ハウジング(21)には、切断室(22)内に臨むエッチング箔投入口(24)と、粉末回収室(23)に臨む粉末回収口(25)とが設けられており、それぞれハウジング(21)に着脱自在に取り付けられた蓋(26)(27)により開閉自在となっている。 The housing (21) of the cutting device (20) is provided with a cutting chamber (22) and a powder recovery chamber (23) located below the cutting chamber (22). The housing (21) is provided with an etching foil inlet (24) facing the cutting chamber (22) and a powder recovery port (25) facing the powder recovery chamber (23). It can be freely opened and closed by means of lids (26) and (27) which are detachably attached to.
　切断装置(20)のハウジング(21)の切断室(22)内に、回転体(28)および回転体(28)の回転方向に間隔をおいて回転体(28)に取り付けられた複数の回転刃(29)を有する回転切断機(30)が設置されている。また、ハウジング(21)には、先端部が切断室(22)内に望むように、複数の固定刃(31)が取り付けられている。そして、回転体(28)が回転させられることによって、回転刃(29)と固定刃(31)とによりエッチング箔が切断される。 In the cutting chamber (22) of the housing (21) of the cutting device (20), a plurality of rotations attached to the rotating body (28) at intervals in the rotating direction of the rotating body (28) and the rotating body (28) A rotary cutting machine (30) having a blade (29) is installed. In addition, a plurality of fixed blades (31) are attached to the housing (21) so that the front end portion is desired in the cutting chamber (22). Then, when the rotating body (28) is rotated, the etching foil is cut by the rotating blade (29) and the fixed blade (31).
　切断装置(20)のハウジング(21)内における切断室(22)と粉末回収室(23)との間には複数のふるい目を有するスクリーン(32)が配置されている。スクリーン(32)のふるい目の目開きは、粒径１５０μｍ以下の粒子のみが通過しうるような大きさに調整されている。 A screen (32) having a plurality of sieves is arranged between the cutting chamber (22) and the powder recovery chamber (23) in the housing (21) of the cutting device (20). The opening of the screen (32) is adjusted so that only particles having a particle size of 150 μm or less can pass through.
　このような切断装置において、エッチング箔を投入口(24)から投入した後に投入口(24)を蓋(26)により塞いで回転体(28)を回転させると、回転刃(29)と固定刃(31)とによって、エッチング箔がスクリーン(32)のふるい目を通る大きさの粒子になるまで切断され、粒径１５０μｍ以下の粒子がスクリーン(32)のふるい目を通って粉末回収室(23)内に入る。その後、蓋(27)を開けて粉末回収室(23)内から粒径１５０μｍ以下の粒子からなる粉末を取り出す。こうして、負極活物質が得られる。 In such a cutting apparatus, when the etching foil is introduced from the inlet (24) and then the inlet (24) is closed by the lid (26) and the rotating body (28) is rotated, the rotary blade (29) and the fixed blade (31), the etching foil is cut until it becomes a particle having a size passing through the sieve of the screen (32), and particles having a particle size of 150 μm or less pass through the sieve of the screen (32), and the powder recovery chamber (23 ) Thereafter, the lid (27) is opened, and the powder composed of particles having a particle size of 150 μm or less is taken out from the powder collection chamber (23). In this way, a negative electrode active material is obtained.
　負極活物質は、図４に示すように、たとえばコイン型のリチウム二次電池(10)に用いられる。コイン型のリチウム二次電池(10)は、ケース(11)内に、負極(12)、負極(12)と対向した正極(13)、負極(12)と正極(13)との間に挟まれたセパレータ(14)、および非水電解質（図示略）が封入されたものである。 The negative electrode active material is used for, for example, a coin-type lithium secondary battery (10) as shown in FIG. The coin-type lithium secondary battery (10) is sandwiched between a negative electrode (12), a positive electrode (13) facing the negative electrode (12), and a negative electrode (12) and a positive electrode (13) in a case (11). The separator (14) and a non-aqueous electrolyte (not shown) are enclosed.
　負極(12)は、集電体(15)上に、負極活物質、導電助剤および結着剤を含む混合物(16)が付着させられたものである。集電体(15)としては、たとえば圧延銅箔や、電解銅箔などの銅箔が用いられる。導電助剤としては、ケッチェンブラックやアセチレンブラックなどが用いられるが、これに限定されるものではない。結着剤としては、ポリフッ化ビニリデンが用いられるが、これに限定されるものではない。 The negative electrode (12) is obtained by adhering a mixture (16) containing a negative electrode active material, a conductive additive and a binder on a current collector (15). As the current collector (15), for example, a rolled copper foil or a copper foil such as an electrolytic copper foil is used. As the conductive auxiliary agent, ketjen black or acetylene black is used, but it is not limited to this. As the binder, polyvinylidene fluoride is used, but is not limited thereto.
　正極(13)としては、たとえばＬｉＣｏＯ2からなるものが活物質として用いられ、当該活物質と導電助剤および結着剤との混合物がアルミニウム箔からなる集電体上に付着されたものが用いられるが、これに限定されるものではない。 As the positive electrode (13), for example, a material made of LiCoO 2 is used as an active material, and a mixture of the active material, a conductive additive and a binder is attached on a current collector made of aluminum foil. However, the present invention is not limited to this.
　上述したリチウム二次電池(10)において、充電時には、Ｌｉイオンが負極(12)に含まれる負極活物質の粒子(1)の孔(2)中に入り込んで孔(2)内でＬｉイオンを含む化合物が形成されるとともに、負極活物質の粒子(1)間に生じた隙間内に入り込んで隙間内でＬｉイオンを含む化合物が形成されることになり、充電時の負極活物質の粒子(1)の膨張を抑制することができる。また、充電時の膨張が抑制されているので、放電時にＬｉイオンが負極活物質の粒子(1)から出る際の粒子(1)の収縮も小さくなる。その結果、充電・放電の際の負極活物質の粒子(1)の体積変化が小さくなり、充電・放電時の負極活物質の粒子(1)の体積変化が大きくなることに起因する粒子(1)の割れや微粉化、ならびに負極活物質の粒子(1)の導電助剤および結着剤からの剥離を効果的に抑制することができるとともに、充電・放電を繰り返すことによる容量低下が少なくなって、リチウム二次電池(10)のサイクル寿命の長寿命化を図ることが可能になる。 In the above-described lithium secondary battery (10), during charging, Li ions enter the pores (2) of the particles (1) of the negative electrode active material contained in the negative electrode (12), and Li ions are contained in the pores (2). In addition to the formation of the compound containing the negative electrode active material particles (1), into the gap formed between the negative electrode active material particles (1) to form a compound containing Li ions in the gap, Expansion of 1) can be suppressed. Further, since the expansion during charging is suppressed, the shrinkage of the particles (1) when Li ions exit from the particles (1) of the negative electrode active material during discharging is also reduced. As a result, the volume change of the negative electrode active material particles (1) during charge / discharge is reduced, and the volume change of the negative electrode active material particles (1) during charge / discharge is increased (1 ) Cracking and pulverization, and separation of the negative electrode active material particles (1) from the conductive assistant and binder, and capacity reduction due to repeated charging and discharging are reduced. Thus, it becomes possible to prolong the cycle life of the lithium secondary battery (10).
　また、リチウム二次電池(10)の初期充放電容量が大きくなるとともに、充放電を繰り返すことによる容量低下が少なくなる。 Also, the initial charge / discharge capacity of the lithium secondary battery (10) is increased, and the capacity reduction due to repeated charge / discharge is reduced.
　上記実施形態においては、この発明による負極活物質がコイン型のリチウム二次電池に用いられているが、これに限定されるものではなく、角型、円筒型、ラミネート型などの公知のリチウム二次電池に用いられる。 In the above embodiment, the negative electrode active material according to the present invention is used in a coin-type lithium secondary battery. However, the present invention is not limited to this, and known lithium secondary batteries such as a square type, a cylindrical type, and a laminate type are used. Used for secondary batteries.
　以下、この発明の具体的実施例を、比較例とともに説明する。
実施例
　市販の中高圧（１７０Ｖ以上の電解コンデンサ用陽極）用に両面エッチングが施されており、かつＦｅ含有量が０．０１質量％であるＡｌ箔を、シュレッダー装置により小片化した後、さらに粉砕装置により粉砕し、粉末からなる負極活物質をつくった。得られた負極活物質中の粒子の粒径は１～５０μｍの範囲内であった。また、電子顕微鏡により負極活物質の粒子を観察したところ、箔の段階で確認された孔が、残存していた。 Hereinafter, specific examples of the present invention will be described together with comparative examples.
Example After double-sided etching for commercially available medium and high voltage (anode for electrolytic capacitor of 170 V or higher) and Fe content of 0.01% by mass was shredded by a shredder device, The negative electrode active material which consists of powder was grind | pulverized with the grinder. The particle diameter of the particles in the obtained negative electrode active material was in the range of 1 to 50 μm. Moreover, when the particles of the negative electrode active material were observed with an electron microscope, the pores confirmed at the foil stage remained.
　ついで、負極活物質：８５重量部と、ポリフッ化ビニリデンからなる結着剤：８重量部と、アセチレンブラックからなる導電助剤：７重量部とを混合し、当該混合物を厚み１０μｍの銅箔からなる集電体上に塗布した。ついで、上記混合物が塗布された集電体を１ｃｍ2の円形ポンチで打ち抜き、これを負極とした。そして、金属Ｌｉを正極とし、正極と負極との間に気孔率４０vol％のミクロポア構造をしたポリエチレンからなるセパレータを挟み、エチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）との混合溶媒（ＥＣ＋ＤＭＣ＝１：１（体積比））に１mol／リットルのＬｉＰＦ6を溶解させた溶液を電解質とし、露点が－５０℃以下の雰囲気であるドライボックス中でコイン型モデル電池（ＣＲ２０３２タイプ）を作製した。
比較例
　純度９９．９９質量％の高純度焼鈍Ａｌ箔を、シュレッダー装置により小片化した後、さらに粉砕装置により粉砕し、粉末からなる負極活物質をつくった。得られた負極活物質中の粒子の粒径は１～５０μｍの範囲内であった。 Then, negative electrode active material: 85 parts by weight, binder made of polyvinylidene fluoride: 8 parts by weight, and conductive auxiliary agent made of acetylene black: 7 parts by weight are mixed, and the mixture is made from a 10 μm thick copper foil. It was applied on a current collector. Next, the current collector coated with the mixture was punched with a 1 cm 2 circular punch, and this was used as the negative electrode. Then, a separator made of polyethylene having a micropore structure with a porosity of 40 vol% is sandwiched between the positive electrode and the negative electrode, and a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (EC + DMC = 1). 1 (volume ratio)) was dissolved in 1 mol / liter LiPF 6 as an electrolyte, and a coin-type model battery (CR2032 type) was produced in a dry box having an atmosphere with a dew point of −50 ° C. or lower.
Comparative Example A high-purity annealed Al foil having a purity of 99.99% by mass was shredded by a shredder apparatus and then pulverized by a pulverizer to produce a negative electrode active material made of powder. The particle diameter of the particles in the obtained negative electrode active material was in the range of 1 to 50 μm.
　ついで、負極活物質：８５重量部と、ポリフッ化ビニリデンからなる結着剤：８重量部と、アセチレンブラックからなる導電助剤：７重量部とを混合し、当該混合物を厚み１０μｍの銅箔からなる集電体上に塗布した。ついで、上記混合物が塗布された集電体を１ｃｍ2の円形ポンチで打ち抜き、これを負極とした。そして、金属Ｌｉを正極とし、正極と負極との間に気孔率４０vol％のミクロポア構造をしたポリエチレンからなるセパレータを挟み、エチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）との混合溶媒（ＥＣ＋ＤＭＣ＝１：１（体積比））に１mol／リットルのＬｉＰＦ6を溶解させた溶液を電解質とし、露点が－５０℃以下の雰囲気であるドライボックス中でコイン型モデル電池（ＣＲ２０３２タイプ）を作製した。
評価試験
　実施例および比較例において作製したモデル電池について、負極の評価を次の方法で行った。 Then, negative electrode active material: 85 parts by weight, binder made of polyvinylidene fluoride: 8 parts by weight, and conductive auxiliary agent made of acetylene black: 7 parts by weight are mixed, and the mixture is made from a 10 μm thick copper foil. It was applied on a current collector. Next, the current collector coated with the mixture was punched with a 1 cm 2 circular punch, and this was used as the negative electrode. Then, a separator made of polyethylene having a micropore structure with a porosity of 40 vol% is sandwiched between the positive electrode and the negative electrode, and a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (EC + DMC = 1). 1 (volume ratio)) was dissolved in 1 mol / liter LiPF 6 as an electrolyte, and a coin-type model battery (CR2032 type) was produced in a dry box having an atmosphere with a dew point of −50 ° C. or lower.
Evaluation test About the model battery produced in the Example and the comparative example, the negative electrode was evaluated by the following method.
　まず、モデル電池を、０．２ｍＡ／ｃｍ2の定電流で１Ｖに達するまで充電し、１０分間休止後、０．２ｍＡ／ｃｍ2の定電流で０Ｖに達するまで放電した。これを、１サイクルとし、繰り返し充放電を行って放電容量を調べた。 First, the model battery was charged at a constant current of 0.2 mA / cm 2 until reaching 1 V, rested for 10 minutes, and then discharged at a constant current of 0.2 mA / cm 2 until it reached 0 V. This was defined as one cycle, and charging / discharging was repeated to examine the discharge capacity.
　実施例および比較例において作製したモデル電池におけるサイクル数と放電容量とを表１に示す。 Table 1 shows the number of cycles and the discharge capacity of the model batteries produced in the examples and comparative examples.
Figure JPOXMLDOC01-appb-T000001
 　表１から明らかなように、実施例において作製したモデル電池では、比較例において作製したモデル電池と比較して初期放電容量が高くなっているとともに、１００サイクル経過後の放電容量の低下も少なく十分な値を維持していることが分かる。したがって、実施例において作製したモデル電池では、比較例において作製したモデル電池と比較してサイクル寿命の長寿命化が達成されている。
Figure JPOXMLDOC01-appb-T000001
 As is apparent from Table 1, the model battery produced in the example has a higher initial discharge capacity than the model battery produced in the comparative example, and the discharge capacity after 100 cycles has decreased sufficiently. It can be seen that this value is maintained. Therefore, in the model battery manufactured in the example, the cycle life is extended as compared with the model battery manufactured in the comparative example.
　この発明によるリチウム二次電池用負極活物質は、リチウム二次電池の負極に好適に用いられ、リチウム二次電池のサイクル寿命の長寿命化を達成することが可能になる。 The negative electrode active material for a lithium secondary battery according to the present invention is suitably used for a negative electrode of a lithium secondary battery, and it is possible to achieve a long cycle life of the lithium secondary battery.

Claims (11)

  1. Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングしてエッチング箔をつくる工程、および当該エッチング箔を切断する工程をこの順序で行うことにより形成された粉末からなるリチウム二次電池用負極活物質。 It was formed by performing an etching foil forming step by etching both surfaces of a foil containing Fe as a main component with an Fe content of 0.05% by mass or less and cutting the etching foil in this order. A negative electrode active material for a lithium secondary battery comprising powder.
  2. Ａｌを主成分とする箔のＡｌ純度が９０質量％以上である請求項１記載のリチウム二次電池用負極活物質。 The negative electrode active material for a lithium secondary battery according to claim 1, wherein the Al purity of the foil containing Al as a main component is 90% by mass or more.
  3. エッチング箔を切断して形成された粉末中に、表面に開口しかつ孔径が０．５μｍ以上である複数の孔を有する粒子が含まれており、孔を有する粒子におけるすべての孔の粒子表面への開口面積の合計が、当該孔を有する各粒子の表面積の１０％以上である請求項１または２記載のリチウム二次電池用負極活物質。 The powder formed by cutting the etching foil contains particles having a plurality of holes that are open on the surface and have a hole diameter of 0.5 μm or more. 3. The negative electrode active material for a lithium secondary battery according to claim 1, wherein the total opening area is 10% or more of the surface area of each particle having the pores.
  4. すべての粒子の粒径が５～１５０μｍであり、孔を有する粒子の孔径が０．５～１５μｍであり、孔を有する粒子における粒径に対する孔径の比（孔径／粒径）が０．１未満である請求項３記載のリチウム二次電池用負極活物質。 The diameter of all particles is 5 to 150 μm, the diameter of the pore-containing particles is 0.5 to 15 μm, and the ratio of the pore diameter to the diameter of the pore-containing particles (pore diameter / particle diameter) is less than 0.1 The negative electrode active material for a lithium secondary battery according to claim 3.
  5. エッチング箔に形成されたすべてのエッチング孔のうち少なくとも一部のエッチング孔が貫通孔である請求項１記載のリチウム二次電池用負極活物質。 2. The negative electrode active material for a lithium secondary battery according to claim 1, wherein at least some of the etching holes formed in the etching foil are through holes.
  6. Ｆｅ含有量が０．０５質量％以下でありかつＡｌを主成分とする箔の両面をエッチングすることによりつくられかつ両面に多孔質層を有するエッチング箔を、切断して粉末とすることを特徴とするリチウム二次電池用負極活物質の製造方法。 Etching foil having a Fe content of 0.05% by mass or less and having a porous layer on both sides, which is made by etching both sides of a foil containing Al as a main component, is cut into powder. A method for producing a negative electrode active material for a lithium secondary battery.
  7. Ａｌを主成分とする箔のＡｌ純度が９０質量％以上である請求項６記載のリチウム二次電池用負極活物質の製造方法。 The manufacturing method of the negative electrode active material for lithium secondary batteries of Claim 6 whose Al purity of the foil which has Al as a main component is 90 mass% or more.
  8. エッチング箔として、厚みが２００μｍ以下、両多孔質層におけるエッチング孔の孔径が０．５～１５μｍ、両多孔質層におけるすべてのエッチング孔の開口面積の合計が、それぞれエッチング箔の両面の表面積の１０％以上であり、すべてのエッチング孔のうちの少なくとも一部のエッチング孔が貫通孔となっているものを用いる請求項６または７記載のリチウム二次電池用負極活物質の製造方法。 The etching foil has a thickness of 200 μm or less, the hole diameters of the etching holes in both porous layers are 0.5 to 15 μm, and the total opening area of all the etching holes in both porous layers is 10% of the surface area of both surfaces of the etching foil. The method for producing a negative electrode active material for a lithium secondary battery according to claim 6 or 7, wherein at least some of the etching holes are through-holes.
  9. エッチング箔として、厚みが５０～１５０μｍであるものを用いる請求項８記載のリチウム二次電池用負極活物質の製造方法。 9. The method for producing a negative electrode active material for a lithium secondary battery according to claim 8, wherein an etching foil having a thickness of 50 to 150 μm is used.
  10. 集電体上に、請求項１記載の負極活物質、導電助剤および結着剤を含む混合物質が付着されているリチウム二次電池用負極。 A negative electrode for a lithium secondary battery, wherein a mixed material containing the negative electrode active material according to claim 1, a conductive additive and a binder is attached on a current collector.
  11. 請求項１０記載の負極と、セパレータと、リチウム二次電池用正極とを備えているリチウム二次電池。 A lithium secondary battery comprising the negative electrode according to claim 10, a separator, and a positive electrode for a lithium secondary battery.
PCT/JP2013/061726 2012-04-24 2013-04-22 Negative electrode active material for a lithium secondary battery and method for manufacturing same WO2013161733A1 (en)

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