JP2013073779A - Method of preparing composition for positive electrode mixture layer formation, and method of manufacturing nonaqueous electrolytic solution secondary battery - Google Patents

Method of preparing composition for positive electrode mixture layer formation, and method of manufacturing nonaqueous electrolytic solution secondary battery Download PDF

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JP2013073779A
JP2013073779A JP2011211909A JP2011211909A JP2013073779A JP 2013073779 A JP2013073779 A JP 2013073779A JP 2011211909 A JP2011211909 A JP 2011211909A JP 2011211909 A JP2011211909 A JP 2011211909A JP 2013073779 A JP2013073779 A JP 2013073779A
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positive electrode
mixture layer
composition
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Yoshiji Iizuka
佳士 飯塚
Masato Kojima
昌人 小島
Masatsugu Ishizawa
政嗣 石澤
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Hitachi Maxell Energy Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide: a method of preparing a composition for positive electrode mixture layer formation which allows the suppression of the decrease of the productivity of a positive electrode involved in the increase in viscosity or gelation while a lithium nickel complex oxide is used as a positive electrode active material; and a method of manufacturing a nonaqueous electrolytic solution secondary battery with a composition for positive electrode mixture layer formation which is prepared by the aforementioned method.SOLUTION: The method of preparing a composition is for formation of a positive electrode mixture layer of a positive electrode for a nonaqueous electrolytic solution secondary battery; the composition includes a positive electrode active material, a conductive assistant, a binder and a solvent. The method comprises at least a mixing step where the positive electrode active material, the conductive assistant, the binder and the solvent are mixed, and a storing step where the mixture obtained by the mixing step is put in a container and stored therein. In the method, a lithium and nickel-containing complex oxide is used as the positive electrode active material, an organic solvent is used as the solvent, and a binder which is soluble in the organic solvent is used as the binder. In the storing step, a carbonic acid gas is introduced into the container.

Description

本発明は、リチウムニッケル複合酸化物を正極活物質に使用しつつ、増粘に伴う正極の生産性の低下を抑制し得る正極合剤層形成用組成物の調製方法と、前記方法により調製される正極合剤層形成用組成物を使用した非水電解液二次電池の製造方法に関するものである。   The present invention is a method for preparing a composition for forming a positive electrode mixture layer capable of suppressing a decrease in productivity of a positive electrode due to thickening while using a lithium nickel composite oxide as a positive electrode active material. The present invention relates to a method for producing a non-aqueous electrolyte secondary battery using the positive electrode mixture layer forming composition.

リチウムイオン二次電池などの非水電解液二次電池は、高電圧・高容量であることから、携帯電話やノート型パソコンなどの電子機器の電源として利用されており、また、電気自動車などへの用途展開も図られている。   Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are used as power sources for electronic devices such as mobile phones and laptop computers because of their high voltage and high capacity. Applications are also being developed.

非水電解液二次電池で使用されている正極は、例えば、正極活物質、導電助剤およびバインダに溶剤を加えて混合することにより、スラリー状やペースト状などの正極合剤層形成用組成物を調製し、この正極合剤層形成用組成物を集電体となる導電性基体の表面に塗布し、溶剤を乾燥除去すると共にプレス処理などを施し、厚みや密度の調整された正極合剤層を形成する工程を経て作製される。   The positive electrode used in the non-aqueous electrolyte secondary battery is, for example, a composition for forming a positive electrode mixture layer such as a slurry or paste by adding a solvent to a positive electrode active material, a conductive additive and a binder and mixing them. The composition for forming a positive electrode mixture layer was applied to the surface of a conductive substrate serving as a current collector, and the solvent was dried and removed, followed by press treatment, etc., to adjust the thickness and density of the positive electrode mixture. It is produced through a step of forming an agent layer.

ところが、水を溶剤に用いた正極合剤層形成用組成物では、正極活物質からＬｉ（リチウム）が溶出しやすく、これがＬｉＯＨを形成して正極合剤層形成用組成物の性状を変化させたり、正極合剤層形成用組成物が塗布される集電体を構成する金属箔を劣化させたりする問題があることが指摘されている。そして、特許文献１および特許文献２には、正極合剤層形成用組成物中で形成したＬｉＯＨを中和して、これらの問題を回避する技術が提案されている。   However, in the composition for forming a positive electrode mixture layer using water as a solvent, Li (lithium) is easily eluted from the positive electrode active material, which changes the properties of the composition for forming a positive electrode mixture layer by forming LiOH. It has been pointed out that there is a problem that the metal foil constituting the current collector to which the composition for forming a positive electrode mixture layer is applied is deteriorated. Patent Documents 1 and 2 propose a technique for neutralizing LiOH formed in the positive electrode mixture layer forming composition to avoid these problems.

特開平８−６９７９１号公報Japanese Patent Laid-Open No. 8-67991 特開２００３−１８７７８７号公報JP 2003-187787 A

ところで、非水電解液二次電池には、更なる高容量化の要請がある。現在の非水電解液二次電池には、ＬｉとＣｏ（コバルト）とを含有するリチウムコバルト複合酸化物が正極活物質として汎用されているが、例えば、これよりも単位質量あたりの容量が大きいＮｉ（ニッケル）を含有するリチウムニッケル複合酸化物を正極活物質に用いることで、電池の高容量化を図ることが検討されている。   By the way, there is a demand for higher capacity in the non-aqueous electrolyte secondary battery. In current non-aqueous electrolyte secondary batteries, a lithium cobalt composite oxide containing Li and Co (cobalt) is widely used as a positive electrode active material. For example, the capacity per unit mass is larger than this. The use of lithium nickel composite oxide containing Ni (nickel) as a positive electrode active material has been studied to increase the capacity of the battery.

しかしながら、リチウムニッケル複合酸化物のようにＮｉを含有するリチウム含有複合酸化物からは、水ではなく有機溶剤を用いた正極合剤層形成用組成物中であっても、Ｌｉが溶出してＬｉＯＨを形成し、これが正極合剤層形成用組成物中のバインダに作用して、組成物の粘度を増大させたりゲル化を引き起こしたりする。粘度が非常に増大したりゲル化を引き起こしたりした正極合剤層形成用組成物は、集電体表面に塗布することができないため、これが正極の生産性、ひいては非水電解液二次電池の生産性を損なう要因となっていた。   However, from lithium-containing composite oxides containing Ni, such as lithium-nickel composite oxides, Li is eluted even in the composition for forming a positive electrode mixture layer using an organic solvent instead of water. This acts on the binder in the composition for forming a positive electrode mixture layer to increase the viscosity of the composition or cause gelation. Since the composition for forming a positive electrode mixture layer whose viscosity has increased greatly or caused gelation cannot be applied to the surface of the current collector, this is the productivity of the positive electrode, and thus the non-aqueous electrolyte secondary battery. It was a factor that impeded productivity.

前記の問題を回避するにあたっては、例えば、正極合剤層形成用組成物の調製段階や保管段階、使用段階において、環境内の水分を厳密に管理することが考えられるが、この場合、組成物の成分組成の点で完全な乾燥環境での作業などが困難であるといった問題や、必要とされる設備が大掛かりになるなどの問題がある。   In order to avoid the above problem, for example, in the preparation stage, storage stage, and use stage of the composition for forming a positive electrode mixture layer, it is conceivable to strictly control moisture in the environment. There are problems that it is difficult to work in a completely dry environment in terms of the component composition, and that the required equipment becomes large.

また、一方で、正極合剤層形成用組成物中に酸を投入して、形成したＬｉＯＨを中和してしまうことも考えられるが、ＬｉＯＨの形成量は一定ではないため、投入する酸の量の調整が難しく、例えば、酸の投入量が多くなりすぎて、中和反応に関与しなかった酸が組成物中に多く残存すると、製造される正極の品質を損なう虞がある。   On the other hand, it may be possible to neutralize the LiOH formed by adding an acid into the composition for forming a positive electrode mixture layer, but the amount of LiOH formed is not constant. It is difficult to adjust the amount. For example, if the amount of acid added is excessive and a large amount of acid that has not participated in the neutralization reaction remains in the composition, the quality of the positive electrode to be produced may be impaired.

本発明は、前記事情に鑑みてなされたものであり、その目的は、リチウムニッケル複合酸化物を正極活物質に使用しつつ、増粘やゲル化に伴う正極の生産性の低下を抑制し得る正極合剤層形成用組成物の調製方法と、前記方法により調製される正極合剤層形成用組成物を使用した非水電解液二次電池の製造方法を提供することにある。   This invention is made | formed in view of the said situation, The objective can suppress the fall of the productivity of the positive electrode accompanying thickening or gelatinization, using a lithium nickel composite oxide for a positive electrode active material. It is in providing the manufacturing method of the composition for positive electrode mixture layer formation, and the manufacturing method of the nonaqueous electrolyte secondary battery using the composition for positive electrode mixture layer formation prepared by the said method.

前記目的を達成し得た本発明の正極合剤層形成用組成物の調製方法は、正極活物質、導電助剤、バインダおよび溶剤を含有し、非水電解液二次電池用の正極の正極合剤層を形成するための組成物を調製する方法であって、前記正極活物質、前記導電助剤、前記バインダおよび前記溶剤を混合する混合工程と、前記混合工程により得られた混合物を容器に収容して保管する保管工程とを少なくとも有しており、前記正極活物質にリチウムニッケル含有複合酸化物を使用し、前記溶剤に有機溶剤を使用し、かつ前記バインダに前記有機溶剤に溶解し得るバインダを使用し、前記保管工程中に、前記容器内に炭酸ガスを導入することを特徴とする。   The method for preparing a composition for forming a positive electrode mixture layer of the present invention that has achieved the above object comprises a positive electrode active material, a conductive additive, a binder and a solvent, and is a positive electrode for a positive electrode for a non-aqueous electrolyte secondary battery. A method for preparing a composition for forming a mixture layer, the mixing step of mixing the positive electrode active material, the conductive additive, the binder and the solvent, and the mixture obtained by the mixing step in a container Storage step of storing and storing in, using a lithium nickel-containing composite oxide as the positive electrode active material, using an organic solvent as the solvent, and dissolving in the organic solvent in the binder The obtained binder is used, and carbon dioxide gas is introduced into the container during the storage step.

また、本発明の非水電解液二次電池の製造方法は、正極、負極、セパレータおよび非水電解液を有する非水電解液二次電池を製造するにあたり、集電体の片面または両面に、本発明の正極合剤層形成用組成物の調製方法により得られた正極合剤層形成用組成物を塗布する工程を経て正極合剤層を形成した正極を用いることを特徴とする。   In addition, the method for producing a non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte secondary battery having a non-aqueous electrolyte. It is characterized by using the positive electrode which formed the positive mix layer through the process of apply | coating the positive mix layer forming composition obtained by the preparation method of the positive mix layer forming composition of this invention.

本発明によれば、リチウムニッケル複合酸化物を正極活物質に使用しつつ、増粘やゲル化に伴う正極の生産性の低下を抑制し得る正極合剤層形成用組成物の調製方法を提供できる。また、本発明の非水電解液二次電池の製造方法によれば、非水電解液二次電池を良好な生産性で製造できる。   ADVANTAGE OF THE INVENTION According to this invention, the preparation method of the composition for positive electrode mixture layer formation which can suppress the productivity fall of the positive electrode accompanying thickening and gelatinization is provided, using lithium nickel composite oxide for a positive electrode active material. it can. Moreover, according to the manufacturing method of the non-aqueous electrolyte secondary battery of this invention, a non-aqueous electrolyte secondary battery can be manufactured with favorable productivity.

本発明に係る非水電解液二次電池の一例を模式的に表す縦断面図である。It is a longitudinal cross-sectional view which represents typically an example of the nonaqueous electrolyte secondary battery which concerns on this invention.

本発明の調製方法により得られる正極合剤層形成用組成物は、非水電解液二次電池の正極に係る正極合剤層を形成するためのものであり、正極活物質、導電助剤、バインダおよび溶剤を含有している。   A composition for forming a positive electrode mixture layer obtained by the preparation method of the present invention is for forming a positive electrode mixture layer according to a positive electrode of a non-aqueous electrolyte secondary battery, and includes a positive electrode active material, a conductive additive, Contains binder and solvent.

本発明法に係る正極合剤層形成用組成物は、正極活物質の少なくとも一部に、リチウムニッケル複合酸化物を使用する。リチウムニッケル複合酸化物は、例えば、現在の非水電解液二次電池の正極活物質として汎用されているＬｉＣｏＯ２などのリチウムコバルト複合酸化物に比べて、単位質量あたりの容量が大きいため、これを含有する正極合剤層形成用組成物を使用して製造される正極を用いることで、非水電解液二次電池の高容量化を図ることができる。 The composition for forming a positive electrode mixture layer according to the method of the present invention uses a lithium nickel composite oxide for at least a part of the positive electrode active material. Since the lithium nickel composite oxide has a larger capacity per unit mass than a lithium cobalt composite oxide such as LiCoO 2 which is widely used as a positive electrode active material of current non-aqueous electrolyte secondary batteries, for example, By using a positive electrode produced using a composition for forming a positive electrode mixture layer containing a non-aqueous electrolyte secondary battery, the capacity can be increased.

リチウムニッケル複合酸化物としては、下記一般式（１）で表される層状リチウムニッケルコバルト複合酸化物（Ａ）［以下、単に化合物（Ａ）という］が好ましい。
ＬｉＮｉｘＣｏ（１−ｘ−ｙ−ｚ）ＭｎｙＭ１ ｚＯ２ （１）
［前記一般式（１）中、０．５≦ｘ≦０．９、０≦ｙ≦０．３、０．００３≦ｚ≦０．０５であり、元素Ｍ１はＬｉ、Ｎｉ、ＣｏおよびＭｎ以外の金属元素であって、Ｍｇ、Ａｌ、Ｔｉ、Ｓｒ、Ｚｒ、Ｎｂ、ＡｇおよびＢａよりなる群から選択される少なくとも１種の元素を含む。］ As the lithium nickel composite oxide, a layered lithium nickel cobalt composite oxide (A) represented by the following general formula (1) [hereinafter simply referred to as compound (A)] is preferable.
LiNi x Co (1-x- y-z) Mn y M 1 z O 2 (1)
[In the general formula (1), 0.5 ≦ x ≦ 0.9, 0 ≦ y ≦ 0.3, 0.003 ≦ z ≦ 0.05, and the element M 1 is Li, Ni, Co, and Mn. And at least one element selected from the group consisting of Mg, Al, Ti, Sr, Zr, Nb, Ag, and Ba. ]

化合物（Ａ）において、Ｎｉは容量向上に寄与する成分であり、前記一般式（１）におけるＮｉの量ｘは、Ｎｉによる容量向上効果を確保する観点から、０．５以上であることが好ましく、０．７５以上であることがより好ましい。ただし、化合物（Ａ）中のＮｉの量が多すぎると、他の元素の量が少なくなって、これらによる効果を良好に確保し得ないことがあるため、前記一般式（１）におけるＮｉの量ｘは、０．９以下であることが好ましく、０．８５以下であることがより好ましい。   In the compound (A), Ni is a component that contributes to the capacity improvement, and the amount x of Ni in the general formula (1) is preferably 0.5 or more from the viewpoint of securing the capacity improvement effect by Ni. 0.75 or more is more preferable. However, if the amount of Ni in the compound (A) is too large, the amount of other elements decreases, and the effects of these may not be ensured satisfactorily. The amount x is preferably 0.9 or less, and more preferably 0.85 or less.

また、化合物（Ａ）において、結晶格子中にＭｎを存在させると、Ｎｉとともに層状の構造を安定化させ、化合物（Ａ）の熱的安定性を向上させ得ることから、より安全性の高い電池を構成可能な正極を得るための正極合剤層形成用組成物を調製することができる。前記一般式（１）におけるＭｎの量ｙは、０．３以下であることが好ましく、０．２以下であることがより好ましい。また、前記一般式（１）におけるＭｎの量ｙは、０であってもよいが、前記の効果を確保する観点からは、０．１以上であることが好ましい。   Further, in the compound (A), when Mn is present in the crystal lattice, the layered structure can be stabilized together with Ni, and the thermal stability of the compound (A) can be improved. The composition for positive electrode mixture layer formation for obtaining the positive electrode which can comprise can be prepared. In the general formula (1), the amount y of Mn is preferably 0.3 or less, and more preferably 0.2 or less. Moreover, although 0 may be sufficient as the quantity y of Mn in the said General formula (1), it is preferable that it is 0.1 or more from a viewpoint of ensuring the said effect.

更に、化合物（Ａ）は、元素Ｍ１として、Ｌｉ、Ｎｉ、ＣｏおよびＭｎ以外の金属元素であって、Ｍｇ、Ａｌ、Ｔｉ、Ｓｒ、Ｚｒ、Ｎｂ、ＡｇおよびＢａよりなる群から選択される少なくとも１種の元素を含んでおり、これらの元素を含有することによっても、その安定性を高めて、より安全性の高い電池を構成可能な正極を得るための正極合剤層形成用組成物の調製が可能となる。元素Ｍ１によるこのような効果を良好に確保する観点から、前記一般式（１）における元素Ｍ１の量ｚは、０．００３以上であることが好ましく、０．０１以上であることがより好ましい。ただし、化合物（Ａ）中の元素Ｍ１の量が多すぎると、他の元素の量が少なくなって、これらによる効果を良好に確保し得ないため、前記一般式（１）における元素Ｍ１の量ｚは、０．０５以下であることが好ましく、０．０４以下であることがより好ましい。 Further, compound (A), as the element M 1, Li, Ni, a metal element other than Co and Mn, are selected Mg, Al, Ti, Sr, Zr, Nb, from the group consisting of Ag and Ba A composition for forming a positive electrode mixture layer for obtaining a positive electrode capable of constituting a safer battery by containing at least one element and improving the stability even when these elements are contained. Can be prepared. Such effect element M 1 from the viewpoint of satisfactorily ensuring the amount z of the element M 1 in the general formula (1) is more be preferably 0.003 or more, 0.01 or more preferable. However, if the amount of the element M 1 in the compound (A) is too large, the amount of other elements decreases, and the effects of these cannot be secured satisfactorily. Therefore, the element M 1 in the general formula (1) The amount z of is preferably 0.05 or less, and more preferably 0.04 or less.

また、化合物（Ａ）において、その結晶格子中にＣｏを存在させると、電池の充放電でのＬｉの脱離および挿入による化合物（Ａ）の相転移から起こる不可逆反応を緩和でき、化合物（Ａ）の結晶構造の可逆性を高めることができるため、充放電サイクル寿命の長い電池を構成可能な正極を得るための正極合剤層形成用組成物の調製が可能となる。前記一般式（１）において、Ｃｏの量は「１−ｘ−ｙ−ｚ」で表されるが、具体的には、０.０５〜０．４であることが好ましい。   In addition, in the compound (A), when Co is present in the crystal lattice, the irreversible reaction resulting from the phase transition of the compound (A) due to the elimination and insertion of Li during charge / discharge of the battery can be mitigated. ), The composition for forming a positive electrode mixture layer for obtaining a positive electrode capable of constituting a battery having a long charge / discharge cycle life can be prepared. In the general formula (1), the amount of Co is represented by “1-xyz”, and specifically, it is preferably 0.05 to 0.4.

リチウムニッケル複合酸化物［前記化合物（Ａ）を含む］からは、水分との共存下でＬｉが溶出してＬｉＯＨを形成し、これが正極合剤層形成用組成物中のバインダに作用して、正極合剤層形成用組成物の増粘やゲル化を引き起こす。しかし、本発明法により調製される正極合剤層形成用組成物であれば、その保管途中におけるＬｉの溶出による増粘やゲル化を抑制することができる。   From the lithium nickel composite oxide [including the compound (A)], Li elutes in the presence of moisture to form LiOH, which acts on the binder in the positive electrode mixture layer forming composition, Causes thickening and gelation of the positive electrode mixture layer forming composition. However, the composition for forming a positive electrode mixture layer prepared by the method of the present invention can suppress thickening and gelation due to Li elution during storage.

なお、リチウムニッケル複合酸化物は、通常、ＬｉＯＨなどのアルカリ性のリチウム含有化合物を原材料として合成される。よって、リチウムニッケル複合酸化物には、未反応のリチウム含有化合物が残存し、これも正極合剤層形成用組成物の保管途中における増粘やゲル化の原因となることがある。よって、本発明法で使用される正極活物質は、未反応のリチウム含有化合物の残存量が少ないことが好ましい。   Note that the lithium nickel composite oxide is usually synthesized using an alkaline lithium-containing compound such as LiOH as a raw material. Therefore, an unreacted lithium-containing compound remains in the lithium nickel composite oxide, which may cause thickening or gelation during storage of the positive electrode mixture layer forming composition. Therefore, the positive electrode active material used in the method of the present invention preferably has a small residual amount of unreacted lithium-containing compound.

正極活物質中の未反応のリチウム含有化合物の量は、例えば、正極活物質を水洗してリチウム含有化合物を除去したり、未反応のリチウム含有化合物の量の多い正極活物質［例えば化合物（Ａ）］と、未反応のリチウム含有化合物の量の少ない正極活物質とを混合したりすることが好ましい。   The amount of the unreacted lithium-containing compound in the positive electrode active material is, for example, by washing the positive electrode active material with water to remove the lithium-containing compound, or the positive electrode active material [for example, compound (A )] And a positive electrode active material with a small amount of unreacted lithium-containing compound are preferably mixed.

例えば、化合物（Ａ）においても、Ｎｉの量が特に多いものでは、未反応のリチウム含有化合物の量も多いため、水洗を行って前記リチウム含有化合物を除去することが好ましいが、この場合、水洗を複数回繰り返し行わないと、未反応のリチウム含有化合物の量を十分に低減できない一方で、水洗の回数を増やすと化合物（Ａ）が失活する虞がある。よって、Ｎｉの量が特に多い化合物（Ａ）の場合［例えば、前記一般式（１）におけるＮｉの量ｘが、０．７以上０．９以下程度］には、１〜２回程度水洗を行って、未反応のリチウム含有化合物の量をある程度減らした上で、未反応のリチウム含有化合物の量の少ない別の正極活物質（リチウム含有複合酸化物）と併用し、正極活物質全量中における未反応のリチウム含有化合物の量を減らして使用することが好ましい。   For example, in the compound (A), when the amount of Ni is particularly large, the amount of unreacted lithium-containing compound is also large. Therefore, it is preferable to remove the lithium-containing compound by washing with water. If the step is not repeated a plurality of times, the amount of the unreacted lithium-containing compound cannot be sufficiently reduced. On the other hand, if the number of washings is increased, the compound (A) may be deactivated. Therefore, in the case of the compound (A) having a particularly large amount of Ni [for example, the amount x of Ni in the general formula (1) is about 0.7 or more and 0.9 or less], washing with water once or twice is performed. The amount of unreacted lithium-containing compound is reduced to some extent, and then used together with another positive electrode active material (lithium-containing composite oxide) with a small amount of unreacted lithium-containing compound. It is preferable to use by reducing the amount of the unreacted lithium-containing compound.

他方、化合物（Ａ）のうち、Ｎｉの量の少ないもの［例えば、前記一般式（１）におけるＮｉの量ｘが、０．５以上０．７未満程度］は、未反応のリチウム含有化合物の量も比較的少ないため、１回程度の水洗によって未反応のリチウム含有化合物の量を前記の値に調整でき、失活も抑制できるため、化合物（Ａ）のみを正極活物質として正極合剤層形成用組成物の調製に使用してもよく、また、水洗を行うことなく、未反応のリチウム含有化合物の量の少ない別の正極活物質（リチウム含有複合酸化物）と併用して、正極活物質全量中の未反応のリチウム含有化合物の量を減らしてもよい。   On the other hand, among the compounds (A), those having a small amount of Ni [for example, the amount x of Ni in the general formula (1) is about 0.5 or more and less than 0.7] are unreacted lithium-containing compounds. Since the amount is also relatively small, the amount of the unreacted lithium-containing compound can be adjusted to the above value by washing once with water, and deactivation can also be suppressed. Therefore, the positive electrode mixture layer using only the compound (A) as the positive electrode active material It may be used for the preparation of a forming composition, and is used in combination with another positive electrode active material (lithium-containing composite oxide) having a small amount of unreacted lithium-containing compound without washing with water. The amount of unreacted lithium-containing compound in the total amount of the substance may be reduced.

化合物（Ａ）と共に別の正極活物質を使用する場合、このような正極活物質には、従来から知られている非水電解液二次電池の正極活物質として利用されているリチウム含有複合酸化物のうち、未反応のリチウム含有化合物の量が少ないものであれば、特に制限なく使用できるが、下記一般式（２）で表される層状リチウムコバルト複合酸化物（Ｂ）［以下、「化合物（Ｂ）」という］を使用することが好ましい。
ＬｉＮｉａＣｏ（１−ａ−ｂ−ｃ）ＭｎｂＭ２ ｃＯ２ （２）
［前記一般式（１）中、０≦ａ≦０．０３、０≦ｂ≦０．０２、０．００３≦ｃ≦０．０１であり、元素Ｍ２はＬｉ、Ｎｉ、ＣｏおよびＭｎ以外の金属元素であって、Ｍｇ、Ａｌ、Ｔｉ、Ｓｒ、Ｚｒ、Ｎｂ、ＡｇおよびＢａよりなる群から選択される少なくとも１種の元素を含む。］ When another positive electrode active material is used together with the compound (A), such a positive electrode active material includes a lithium-containing composite oxide that has been used as a positive electrode active material of a conventionally known non-aqueous electrolyte secondary battery. Of these materials, any lithium-containing compound having a small amount of unreacted lithium can be used without any particular limitation, but the layered lithium cobalt composite oxide (B) represented by the following general formula (2) [hereinafter referred to as “compound (B) "is preferred.
LiNi a Co (1- abc ) Mn b M 2 c O 2 (2)
[In the general formula (1), 0 ≦ a ≦ 0.03, 0 ≦ b ≦ 0.02, 0.003 ≦ c ≦ 0.01, and the element M 2 is other than Li, Ni, Co, and Mn. It is a metal element and contains at least one element selected from the group consisting of Mg, Al, Ti, Sr, Zr, Nb, Ag, and Ba. ]

化合物（Ｂ）において、ＮｉおよびＣｏは容量向上に寄与する成分であるが、前記の通り、Ｎｉの量を多くしすぎると、例えば、不純物である未反応のリチウム含有化合物の量が多くなりすぎる虞があることから、前記一般式（２）におけるＮｉの量ａは、０．０３以下であることが好ましく、０．０２以下であることがより好ましい。また、化合物（Ｂ）はＮｉを含有していなくてもよい［すなわち、前記一般式（２）におけるＮｉの量ａが０でもよい］。   In the compound (B), Ni and Co are components that contribute to an increase in capacity. As described above, if the amount of Ni is excessively large, for example, the amount of unreacted lithium-containing compound that is an impurity is excessively large. Since there exists a possibility, it is preferable that the quantity a of Ni in the said General formula (2) is 0.03 or less, and it is more preferable that it is 0.02 or less. Further, the compound (B) may not contain Ni [that is, the amount a of Ni in the general formula (2) may be 0].

また、化合物（Ｂ）において、結晶格子中にＭｎを存在させると、Ｎｉとともに層状の構造を安定化させ、化合物（Ｂ）の熱的安定性を向上させ得ることから、より安全性の高い電池を構成可能な正極を得るための正極合剤層形成用組成物を調製することができる。前記一般式（２）におけるＭｎの量ｂは、０．０２以下であることが好ましく、０．０１５以下であることがより好ましい。また、前記一般式（２）におけるＭｎの量ｂは、０であってもよいが、前記の効果を確保する観点からは、０．０１以上であることが好ましい。   Further, in the compound (B), when Mn is present in the crystal lattice, the layered structure can be stabilized together with Ni, and the thermal stability of the compound (B) can be improved. The composition for positive electrode mixture layer formation for obtaining the positive electrode which can comprise can be prepared. The amount b of Mn in the general formula (2) is preferably 0.02 or less, and more preferably 0.015 or less. Moreover, although the amount b of Mn in the said General formula (2) may be 0, it is preferable that it is 0.01 or more from a viewpoint of ensuring the said effect.

更に、化合物（Ｂ）は、元素Ｍ２として、Ｌｉ、Ｎｉ、ＣｏおよびＭｎ以外の金属元素であって、Ｍｇ、Ａｌ、Ｔｉ、Ｓｒ、Ｚｒ、Ｎｂ、ＡｇおよびＢａよりなる群から選択される少なくとも１種の元素を含んでおり、これらの元素を含有することによっても、その安定性を高めることができるため、正極合剤層形成用組成物によって得られる正極を用いて構成される電池の安全性をより高めることが可能となる。元素Ｍ２によるこのような効果を良好に確保する観点から、前記一般式（２）における元素Ｍ２の量ｃは、０．００３以上であることが好ましく、０．００４以上であることがより好ましい。ただし、化合物（Ｂ）中の元素Ｍ２の量が多すぎると、他の元素の量が少なくなって、これらによる効果を良好に確保し得ないため、前記一般式（２）における元素Ｍ２の量ｃは、０．０１以下であることが好ましく、０．００８以下であることがより好ましい。 Furthermore, compound (B), as the element M 2, Li, Ni, a metal element other than Co and Mn, are selected Mg, Al, Ti, Sr, Zr, Nb, from the group consisting of Ag and Ba Since at least one kind of element is contained, and the stability can be improved by containing these elements, the battery of the battery constituted by using the positive electrode obtained by the positive electrode mixture layer forming composition It becomes possible to raise safety more. This effect from the viewpoint of satisfactorily ensuring by elements M 2, the amount c of the element M 2 in the formula (2) is more be preferably 0.003 or more, 0.004 or more preferable. However, if the amount of the element M 2 in the compound (B) is too large, the amount of other elements decreases, and the effects of these cannot be ensured satisfactorily. Therefore, the element M 2 in the general formula (2) Is preferably 0.01 or less, more preferably 0.008 or less.

また、前記の通り、化合物（Ｂ）においてＣｏは容量向上に寄与する成分であり、前記一般式（２）において、Ｃｏの量は「１−ａ−ｂ−ｃ」で表されるが、具体的には、０．９９０〜０．９９７であることが好ましい。   In addition, as described above, in the compound (B), Co is a component that contributes to an increase in capacity. In the general formula (2), the amount of Co is represented by “1-abc”. Specifically, it is preferably 0.990 to 0.997.

例えば、化合物（Ａ）と化合物（Ｂ）とを併用する場合、それらの比率は、正極活物質全量中の未反応のリチウム含有化合物の量を十分に低減できる範囲で設定すればよいが、化合物（Ａ）の使用による効果（特に高容量化の効果）を良好に確保する観点からは、正極活物質全量を１００質量％としたときに、化合物（Ａ）の量を、１０質量％以上とすることが好ましく、２０質量％以上とすることがより好ましい。   For example, when the compound (A) and the compound (B) are used in combination, the ratio thereof may be set within a range in which the amount of the unreacted lithium-containing compound in the total amount of the positive electrode active material can be sufficiently reduced. From the viewpoint of favorably securing the effect (especially the effect of increasing the capacity) of the use of (A), when the total amount of the positive electrode active material is 100% by mass, the amount of the compound (A) is 10% by mass or more. It is preferable to make it 20% by mass or more.

また、前記の通り、正極活物質には、リチウムニッケル複合酸化物のみを使用してもよく、例えば化合物（Ａ）のみを使用してもよいが、化合物（Ａ）と化合物（Ｂ）とを併用する場合には、正極活物質全量を１００質量％としたときに、化合物（Ａ）の量を、３０質量％以下とすることが好ましく、２５質量％以下とすることがより好ましい。   As described above, only the lithium nickel composite oxide may be used as the positive electrode active material. For example, only the compound (A) may be used, but the compound (A) and the compound (B) may be used. When used in combination, when the total amount of the positive electrode active material is 100% by mass, the amount of the compound (A) is preferably 30% by mass or less, and more preferably 25% by mass or less.

正極合剤層形成用組成物に係る溶剤には、有機溶剤を使用する。非水電解液二次電池を製造するための正極合剤層形成用組成物に係る溶剤には、水が使用されることも多いが、その場合、リチウムニッケル複合酸化物からのＬｉの溶出を促し、かつＬｉＯＨの形成に関与する水が、前記組成物内に多量に存在することになるため、正極合剤層形成用組成物の保管途中での増粘やゲル化を十分に抑制したり、保管途中に増粘した正極合剤層形成用組成物の粘度を、集電体の塗布に適切な程度に低減したりすることが困難となる。   An organic solvent is used for the solvent relating to the composition for forming a positive electrode mixture layer. In many cases, water is used as a solvent for the composition for forming a positive electrode mixture layer for producing a non-aqueous electrolyte secondary battery. In this case, elution of Li from the lithium nickel composite oxide is performed. Since the water that promotes and participates in the formation of LiOH will be present in a large amount in the composition, it is possible to sufficiently suppress thickening and gelation during storage of the composition for forming a positive electrode mixture layer. It becomes difficult to reduce the viscosity of the composition for forming a positive electrode mixture layer, which has been thickened during storage, to an appropriate level for applying the current collector.

正極合剤層形成用組成物の溶剤に使用し得る有機溶剤としては、例えば、Ｎ−メチル−２−ピロリドン（ＮＭＰ）、アセトン、Ｎ，Ｎ−ジメチルエチレンウレアなどが挙げられ、これらの中でも、ＮＭＰが特に好ましい。   Examples of the organic solvent that can be used as the solvent for the positive electrode mixture layer forming composition include N-methyl-2-pyrrolidone (NMP), acetone, N, N-dimethylethyleneurea, and among these, NMP is particularly preferred.

正極合剤層形成用組成物に係るバインダには、正極合剤層形成用組成物の溶剤（有機溶剤）に溶解可能なバインダを使用する。バインダを溶剤に溶解している状態で含有する正極合剤層形成用組成物では、例えば、バインダが前記溶剤に溶解せずにエマルションの形態で存在している正極合剤層形成用組成物に比べて、バインダがリチウムニッケル複合酸化物由来のＬｉＯＨによる影響を受けやすいことから、それによる問題が発生しやすい。しかしながら、本発明法によれば、バインダが溶剤に溶解している状態であっても、正極合剤層形成用組成物の保管途中での増粘やゲル化を十分に抑制することができる。   The binder which concerns on the composition for positive electrode mixture layer formation uses the binder which can be melt | dissolved in the solvent (organic solvent) of the composition for positive electrode mixture layer formation. In the composition for forming a positive electrode mixture layer containing a binder dissolved in a solvent, for example, in the composition for forming a positive electrode mixture layer in which the binder does not dissolve in the solvent and exists in the form of an emulsion. In comparison, since the binder is easily affected by LiOH derived from the lithium nickel composite oxide, problems due to it are likely to occur. However, according to the method of the present invention, even when the binder is dissolved in the solvent, thickening and gelation during storage of the positive electrode mixture layer forming composition can be sufficiently suppressed.

前記バインダの具体例としては、例えば、ポリフッ化ビニリデン（ＰＶＤＦ）、フッ化ビニリデンと他の単量体との共重合体［フッ化ビニリデン−クロロトリフルオロエチレン共重合体（ＶＤＦ−ＣＴＦＥ）、フッ化ビニリデン−テトラフルオロエチレン共重合体（ＶＤＦ−ＴＦＥ）、フッ化ビニリデン−ヘキサフルオロプロピレン−テトラフルオロエチレン共重合体（ＶＤＦ−ＨＦＰ−ＴＦＥ）］、ポリテトラフルオロエチレン（ＰＴＦＥ）などのフッ素樹脂などが挙げられる。これらの中でも、少なくとも、ポリフッ化ビニリデン（ＰＶＤＦ）を使用することが好ましい。ＰＶＤＦは高い結着力を有しているため、本発明法に係る正極合剤層形成用組成物がバインダとしてＰＶＤＦを含有している場合には、それにより形成される正極合剤層の性状が良好となるからである。   Specific examples of the binder include, for example, polyvinylidene fluoride (PVDF), a copolymer of vinylidene fluoride and other monomers [vinylidene fluoride-chlorotrifluoroethylene copolymer (VDF-CTFE), fluorine Fluorine resins such as vinylidene fluoride-tetrafluoroethylene copolymer (VDF-TFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer (VDF-HFP-TFE)], polytetrafluoroethylene (PTFE), etc. Is mentioned. Among these, it is preferable to use at least polyvinylidene fluoride (PVDF). Since PVDF has a high binding force, when the composition for forming a positive electrode mixture layer according to the method of the present invention contains PVDF as a binder, the properties of the positive electrode mixture layer formed thereby are It is because it becomes favorable.

その一方で、リチウムニッケル複合酸化物とともにＰＶＤＦを含む正極合剤層形成用組成物は、その保管途中において、内部で形成されたＬｉＯＨの影響によって、特に増粘したりゲル化したりしやすい。ＰＶＤＦはＬｉＯＨによって脱フッ酸を生じやすく、これがＰＶＤＦの分子量増大や架橋構造の形成を促し、正極合剤層形成用組成物の増粘やゲル化を引き起こしているものと推測される。しかしながら、本発明法によれば、ＰＶＤＦをバインダに用いた場合でも、正極合剤層形成用組成物の保管途中での増粘やゲル化を十分に抑制することができる。   On the other hand, the composition for forming a positive electrode mixture layer containing PVDF together with the lithium nickel composite oxide is particularly likely to thicken or gel due to the influence of LiOH formed inside during the storage. PVDF is liable to cause dehydrofluorination by LiOH, which promotes increase in the molecular weight of PVDF and formation of a crosslinked structure, which is presumed to cause thickening and gelation of the positive electrode mixture layer forming composition. However, according to the method of the present invention, even when PVDF is used for the binder, thickening and gelation during storage of the positive electrode mixture layer forming composition can be sufficiently suppressed.

前記溶剤に溶解可能なバインダは、前記の例示のもののうち１種のみを用いてもよく、２種以上を併用してもよい。   As the binder that can be dissolved in the solvent, only one of the above-described examples may be used, or two or more may be used in combination.

正極合剤層形成用組成物に係る導電助剤には、天然黒鉛（鱗片状黒鉛など）、人造黒鉛などのグラファイト類；アセチレンブラック、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックなどのカ−ボンブラック類；炭素繊維；などの炭素材料を用いることが好ましく、また、金属繊維などの導電性繊維類；フッ化カーボン；アルミニウムなどの金属粉末類；酸化亜鉛；チタン酸カリウムなどの導電性ウィスカー類；酸化チタンなどの導電性金属酸化物；ポリフェニレン誘導体などの有機導電性材料；などを用いることもできる。   Examples of conductive aids for the composition for forming a positive electrode mixture layer include graphites such as natural graphite (flaky graphite, etc.) and artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black It is preferable to use carbon materials such as carbon blacks; conductive fibers such as metal fibers; carbon fluorides; metal powders such as aluminum; zinc oxide; potassium titanate, etc. Conductive whiskers, conductive metal oxides such as titanium oxide, organic conductive materials such as polyphenylene derivatives, and the like can also be used.

本発明法により調製される正極合剤層形成用組成物において、正極活物質、バインダおよび導電助剤を含めた固形分（溶剤以外の成分。以下同じ。）の濃度は、例えば、７２〜８６質量％であることが好ましい。また、正極合剤層形成用組成物に係る固形分全量中において、正極活物質の量は９６〜９８質量％であることが好ましく、バインダの量は１．０〜１．５質量％であることが好ましく、導電助剤の量は０．９〜２.０質量％であることが好ましい。   In the composition for forming a positive electrode mixture layer prepared by the method of the present invention, the concentration of the solid content (components other than the solvent; the same applies hereinafter) including the positive electrode active material, the binder, and the conductive additive is, for example, 72 to 86. It is preferable that it is mass%. Moreover, in the total amount of solid content of the composition for forming a positive electrode mixture layer, the amount of the positive electrode active material is preferably 96 to 98% by mass, and the amount of the binder is 1.0 to 1.5% by mass. The amount of the conductive auxiliary is preferably 0.9 to 2.0% by mass.

本発明の正極合剤層形成用組成物の調製方法では、少なくとも、混合工程と保管工程とを設ける。   In the method for preparing a composition for forming a positive electrode mixture layer of the present invention, at least a mixing step and a storage step are provided.

前記混合工程では、正極活物質、導電助剤、バインダおよび溶剤などを混合する。その混合方法については特に制限はなく、例えば、従来から知られているバッチ方式の混合機（混練機。プラネタリーミキサーなど。）を用いて、前記の各成分を混合（混練）する方法が採用できる。また、混合工程での手順も特に制限はなく、前記の各成分を混合機に一度に投入して混合してもよく、予めバインダを溶剤に溶解した溶液を調製しておき、これを正極活物質や導電助剤などとともに混合機に投入して混合してもよい。更に、混合工程では、二軸混練押出機（連続式の二軸混練押出機）を用いて連続的に各成分の混合を行ってもよい。   In the mixing step, a positive electrode active material, a conductive additive, a binder, a solvent, and the like are mixed. The mixing method is not particularly limited, and for example, a method of mixing (kneading) each of the above components using a conventionally known batch type mixer (kneader, planetary mixer, etc.) is employed. it can. The procedure in the mixing step is not particularly limited, and the components described above may be added to the mixer at once and mixed. A solution in which a binder is dissolved in a solvent is prepared in advance, and this is used as a positive electrode active material. You may mix with a substance, a conductive support agent, etc. by throwing into a mixer. Furthermore, in the mixing step, each component may be continuously mixed using a twin-screw kneading extruder (continuous twin-screw kneading extruder).

前記の通り、正極活物質として使用されるリチウムニッケル複合酸化物からは、例えば、正極合剤層形成用組成物の保管途中でＬｉが溶出してＬｉＯＨが形成されるが、このようなＬｉの溶出は、前記混合工程においても生じ得る。よって、前記混合工程においては、正極活物質、導電助剤、バインダおよび溶剤などの混合を、炭酸ガスを導入した系内で行うことが好ましい。混合工程途中でリチウムニッケル複合酸化物からのＬｉの溶出により生じたＬｉＯＨを、導入した炭酸ガスによって中和して、正極合剤層形成用組成物の増粘やゲル化を引き起こさないＬｉ２ＣＯ３にすることができるため、後述する保管工程での正極合剤層形成用組成物の増粘やゲル化を、更に抑制することが可能となる。また、ＬｉＯＨの中和反応に関与しなかった炭酸ガスは、正極の正極合剤層に多量に残存することはないため、ＬｉＯＨの中和処理に付随する正極の特性低下も抑制することができる。 As described above, from the lithium nickel composite oxide used as the positive electrode active material, for example, Li elutes and LiOH is formed during storage of the positive electrode mixture layer forming composition. Elution can also occur in the mixing step. Therefore, in the mixing step, it is preferable to mix the positive electrode active material, the conductive additive, the binder, the solvent, and the like in a system into which carbon dioxide gas is introduced. Li 2 CO that does not cause thickening or gelation of the composition for forming a positive electrode mixture layer by neutralizing LiOH generated by elution of Li from the lithium nickel composite oxide during the mixing process with the introduced carbon dioxide gas it is possible to 3, thickening and gelling of the positive electrode mixture layer-forming composition in the storage step to be described later, it is possible to further suppress. In addition, since carbon dioxide gas that has not been involved in the LiOH neutralization reaction does not remain in a large amount in the positive electrode mixture layer of the positive electrode, it is possible to suppress deterioration in the characteristics of the positive electrode accompanying the LiOH neutralization treatment. .

混合工程において導入する炭酸ガスの量は、モル基準で、正極活物質中のＬｉＯＨ量に対して同等以上とすることが好ましい。炭酸ガスの導入量が少なすぎると、中和しきれないＬｉＯＨ量が多くなるため、正極合剤層形成用組成物の増粘やゲル化を抑制する効果が小さくなる虞があるからである。   The amount of carbon dioxide introduced in the mixing step is preferably equal to or greater than the amount of LiOH in the positive electrode active material on a molar basis. This is because if the amount of carbon dioxide introduced is too small, the amount of LiOH that cannot be neutralized increases, and the effect of suppressing the thickening and gelation of the positive electrode mixture layer forming composition may be reduced.

炭酸ガスを導入した系内の前記混合は、例えば、前記のバッチ方式の混合機の混合系内（混合槽内）に前記の各成分を投入し、更に炭酸ガスを封入した後に混合を行うことにより実施できる。また、前記の二軸混練押出機を使用する場合には、二軸混練押出機内に炭酸ガスを連続的に供給しつつ、各成分の混練を行えばよい。   The mixing in the system into which the carbon dioxide gas has been introduced is performed, for example, by adding each of the above components into the mixing system (mixing tank) of the batch-type mixer, and further mixing the carbon dioxide gas after sealing. Can be implemented. Moreover, when using the said biaxial kneading extruder, what is necessary is just to knead | mix each component, supplying a carbon dioxide gas continuously in a biaxial kneading extruder.

本発明法の前記保管工程では、前記混合工程により得られた混合物、すなわち、正極合剤層形成用組成物を容器に収容して保管する。   In the storage step of the method of the present invention, the mixture obtained in the mixing step, that is, the positive electrode mixture layer forming composition is stored in a container.

この保管工程では、正極合剤層形成用組成物内のリチウムニッケル複合酸化物からＬｉが溶出してＬｉＯＨが形成され、それにより正極合剤層形成用組成物の増粘やゲル化が生じやすい。   In this storage step, Li is eluted from the lithium nickel composite oxide in the composition for forming a positive electrode mixture layer to form LiOH, thereby causing thickening and gelation of the composition for forming a positive electrode mixture layer. .

そこで、本発明法の前記保管工程では、正極合剤層形成用組成物を収容した前記容器内に炭酸ガスを導入する。例えば、前記保管工程の初期から前記容器内に炭酸ガスを導入した場合には、正極合剤層形成用組成物内でＬｉＯＨが形成されても、容器内の炭酸ガスによって、これが速やかに中和され、正極合剤層形成用組成物内に存在しても増粘やゲル化を引き起こさないＬｉ２ＣＯ３が形成される。そのため、前記保管工程の初期から前記容器内に炭酸ガスを導入することで、保管途中での正極合剤層形成用組成物の増粘やゲル化を抑制することができる。 Therefore, in the storage step of the method of the present invention, carbon dioxide gas is introduced into the container containing the positive electrode mixture layer forming composition. For example, when carbon dioxide gas is introduced into the container from the beginning of the storage step, even if LiOH is formed in the composition for forming a positive electrode mixture layer, this is quickly neutralized by the carbon dioxide gas in the container. Li 2 CO 3 that does not cause thickening or gelation even when present in the composition for forming a positive electrode mixture layer is formed. Therefore, by introducing carbon dioxide gas into the container from the initial stage of the storage step, thickening and gelation of the positive electrode mixture layer forming composition during storage can be suppressed.

また、例えば容器内に炭酸ガスを導入しない状態で保管を開始するなどして、保管途中でＬｉＯＨの影響によって多少増粘してしまった正極合剤層形成用組成物が収容されている前記容器内に炭酸ガスを導入した場合には、それ以後の正極合剤層形成用組成物の増粘を抑えることができる。よって、保管途中の容器内に炭酸ガスを導入することによっても、正極合剤層形成用組成物の増粘やゲル化を抑制することができる。   Further, for example, the container in which the composition for forming a positive electrode mixture layer that has been slightly thickened due to the influence of LiOH during the storage by starting storage without introducing carbon dioxide gas into the container is contained. In the case where carbon dioxide gas is introduced, the subsequent thickening of the positive electrode mixture layer forming composition can be suppressed. Therefore, thickening and gelling of the composition for forming a positive electrode mixture layer can also be suppressed by introducing carbon dioxide into a container during storage.

本発明法によれば、このように、保管途中での正極合剤層形成用組成物の品質低下を抑制することが可能であることから、保管を経ても使用できなくなる正極合剤層形成用組成物の割合を大幅に低減することができる。そのため、本発明法によれば、非水電解液二次電池用正極の生産性、ひいては、非水電解液二次電池の生産性を高めることができる。   According to the method of the present invention, since it is possible to suppress the deterioration of the quality of the positive electrode mixture layer forming composition during storage in this way, the positive electrode mixture layer forming that cannot be used even after storage. The proportion of the composition can be greatly reduced. Therefore, according to the method of the present invention, the productivity of the positive electrode for a non-aqueous electrolyte secondary battery, and thus the productivity of the non-aqueous electrolyte secondary battery can be increased.

正極合剤層形成用組成物は、例えば、集電体表面に良好に塗布し得るようにするために、前記混合工程直後の粘度が３０００〜１２０００Ｐａ・ｓとなるように調製することが好ましい。このような粘度となるように調製した正極合剤層形成用組成物は、その後の保管工程において、例えば、その保管開始時に、正極合剤層形成用組成物を収容した容器内に炭酸ガスを十分に導入していない場合には、前記の通り、増粘することがある。しかし、保管の途中からでも正極合剤層形成用組成物を収容している容器内に炭酸ガスを導入することで、例えば、その粘度を５０００〜１４０００Ｐａ・ｓ程度に維持し、更なる増粘やゲル化を抑制できるため、正極合剤層形成用組成物の集電体への良好な塗布性を維持することができる。   The composition for forming a positive electrode mixture layer is preferably prepared such that the viscosity immediately after the mixing step is 3000 to 12000 Pa · s, for example, so that the composition can be satisfactorily applied to the current collector surface. In the subsequent storage step, for example, at the start of storage, the composition for forming a positive electrode mixture layer formed so as to have such a viscosity contains carbon dioxide gas in a container containing the composition for forming a positive electrode mixture layer. If not sufficiently introduced, the viscosity may increase as described above. However, by introducing carbon dioxide gas into the container containing the composition for forming the positive electrode mixture layer even in the middle of storage, for example, the viscosity is maintained at about 5000 to 14000 Pa · s to further increase the viscosity. And gelation can be suppressed, so that good applicability of the positive electrode mixture layer forming composition to the current collector can be maintained.

本明細書でいう正極合剤層形成用組成物の粘度は、コーンプレート型粘度計（東機産業製「ＴＶＥ２２Ｈ」、コーンプレート１°３４’×Ｒ２４）を用い、恒温槽で２５℃に温度調節しながら、０．５ｒｐｍの条件でコーンプレートを回転させ、３分後に測定される値である。   The viscosity of the positive electrode mixture layer forming composition referred to in this specification is a cone plate viscometer (“TVE22H” manufactured by Toki Sangyo Co., Ltd., cone plate 1 ° 34 ′ × R24), and the temperature is set to 25 ° C. in a constant temperature bath. The value is measured after 3 minutes by rotating the cone plate under the condition of 0.5 rpm while adjusting.

前記混合工程直後の正極合剤層形成用組成物の粘度は、例えば、前記混合工程で使用する各成分の組成比率を調節することにより調整できる。   The viscosity of the composition for forming a positive electrode mixture layer immediately after the mixing step can be adjusted, for example, by adjusting the composition ratio of each component used in the mixing step.

前記保管工程において、正極合剤層形成用組成物を収容した容器内への炭酸ガスの導入（保管開始時からの導入および保管途中の導入）は、例えば、前記容器内を脱気し、続いて炭酸ガスを導入して常圧に戻す方法により実施することができる。なお、炭酸ガスの導入により常圧とした前記容器内の圧力は、時間の経過とともに低下することがある。よって、必要に応じて、前記容器内の圧力がある程度低下した段階で、再度炭酸ガスを前記容器内に導入する操作を繰り返してもよい。   In the storage step, introduction of carbon dioxide gas into the container containing the composition for forming a positive electrode mixture layer (introduction from the start of storage and introduction during storage) is performed, for example, by degassing the inside of the container. Then, carbon dioxide gas can be introduced to return to normal pressure. In addition, the pressure in the said container made into normal pressure by introduction | transduction of a carbon dioxide gas may fall with progress of time. Therefore, if necessary, the operation of introducing the carbon dioxide gas into the container again may be repeated when the pressure in the container is reduced to some extent.

本発明法の前記保管工程においては、保管開始時から前記容器内へ炭酸ガスを導入することがより好ましく、また、保管途中に前記容器内の圧力がある程度低下する毎に、再度炭酸ガスを前記容器内に導入する操作を繰り返すことが更に好ましい。これらの操作によって、保管途中の正極合剤層形成用組成物の増粘およびゲル化を、より良好に抑制でき、正極および非水電解液二次電池の生産性をより高めることができる。   In the storage step of the method of the present invention, it is more preferable to introduce carbon dioxide gas into the container from the start of storage, and every time the pressure in the container decreases to some extent during storage, the carbon dioxide gas is added again. More preferably, the operation of introducing into the container is repeated. By these operations, thickening and gelation of the composition for forming a positive electrode mixture layer during storage can be suppressed more favorably, and the productivity of the positive electrode and the nonaqueous electrolyte secondary battery can be further increased.

本発明の非水電解液二次電池の製造方法は、正極集電体の片面または両面に、本発明の調製方法により得られた正極合剤層形成用組成物を塗布する工程を経て正極合剤層を形成した正極を用いることを特徴としており、その他の工程（負極の製造工程、正極と負極との間にセパレータを介在させて電極体を製造する工程、電池の組み立て工程など）については、従来から知られている非水電解液二次電池の製造時に採用されている工程と同様とすることができる。   The method for producing a non-aqueous electrolyte secondary battery of the present invention comprises applying a composition for forming a positive electrode mixture layer obtained by the preparation method of the present invention to one or both surfaces of a positive electrode current collector. It is characterized by using a positive electrode in which an agent layer is formed, and other processes (a negative electrode manufacturing process, a process of manufacturing an electrode body with a separator interposed between the positive electrode and the negative electrode, a battery assembly process, etc.) The steps can be the same as those employed in the manufacture of conventionally known non-aqueous electrolyte secondary batteries.

すなわち、本発明の非水電解液二次電池の製造方法では、調製後の増粘やゲル化が抑制されていたり、一旦増大した粘度が集電体の塗布に適切な程度に低下されていたりする本発明法に係る正極合剤層形成用組成物を使用することから、品質の安定した非水電解液二次電池を良好な生産性で製造できる。   That is, in the method for producing a non-aqueous electrolyte secondary battery of the present invention, thickening and gelation after preparation are suppressed, or the once-increased viscosity is reduced to an appropriate level for the application of the current collector. Since the composition for forming a positive electrode mixture layer according to the method of the present invention is used, a non-aqueous electrolyte secondary battery with stable quality can be produced with good productivity.

正極集電体は、構成される電池において実質上化学的に安定な電子伝導体であれば特に制限はない。例えば、集電体を構成する材料としては、アルミニウムやその合金、ステンレス鋼、ニッケルやその合金、チタンやその合金、炭素、導電性樹脂などの他に、アルミニウムまたはステンレス鋼の表面にカーボンまたはチタンを処理させたものなどが用いられる。これらの中でも、アルミニウムおよびアルミニウム合金が特に好ましい。これらの材料は表面を酸化して用いることもできる。また、表面処理により集電体表面に凹凸を付けることが好ましい。集電体の形状としては、フォイルの他、フィルム、シート、ネット、パンチングされたもの、ラス体、多孔質体、発泡体、繊維群の成形体などが挙げられる。正極集電体の厚みは特に限定されないが、例えば、５〜５０μｍであることが好ましい。   The positive electrode current collector is not particularly limited as long as it is an electron conductor that is substantially chemically stable in the battery that is constructed. For example, as a material constituting the current collector, in addition to aluminum or its alloy, stainless steel, nickel or its alloy, titanium or its alloy, carbon, conductive resin, carbon or titanium on the surface of aluminum or stainless steel What processed this is used. Of these, aluminum and aluminum alloys are particularly preferable. These materials can also be used after oxidizing the surface. Moreover, it is preferable to give an unevenness | corrugation to the collector surface by surface treatment. Examples of the shape of the current collector include films, sheets, nets, punched materials, lath bodies, porous bodies, foamed bodies, and molded bodies of fiber groups, in addition to foils. Although the thickness of a positive electrode electrical power collector is not specifically limited, For example, it is preferable that it is 5-50 micrometers.

正極の製造工程においては、前記のような正極集電体の片面または両面に、本発明法により調製された正極合剤層形成用組成物を塗布し、例えば乾燥して組成物中の溶剤を除去し、更に必要に応じてカレンダー成形などのプレス処理を施して正極合剤層を形成し、正極を得る。   In the production process of the positive electrode, the positive electrode mixture layer forming composition prepared by the method of the present invention is applied to one or both surfaces of the positive electrode current collector as described above, for example, dried to remove the solvent in the composition. Then, if necessary, press treatment such as calendering is performed to form a positive electrode mixture layer to obtain a positive electrode.

正極合剤層形成用組成物を正極集電体の表面に塗布する方法については、特に制限はなく、従来から知られている各種の塗布方法を採用することができる。また、プレス処理時の条件としては、例えば、線圧を７００〜２０００ｋｇｆ／ｃｍとすることが好ましい。   There is no restriction | limiting in particular about the method of apply | coating the composition for positive mix layer formation to the surface of a positive electrode electrical power collector, The various application | coating method known conventionally can be employ | adopted. Moreover, as conditions at the time of a press process, it is preferable that a linear pressure shall be 700-2000 kgf / cm, for example.

正極合剤層の厚み（集電体の両面に正極合剤層が形成されている場合には、その片面あたりの厚み）は、３０〜８０μｍであることが好ましい。   The thickness of the positive electrode mixture layer (when the positive electrode mixture layer is formed on both surfaces of the current collector, the thickness per one surface thereof) is preferably 30 to 80 μm.

負極の製造工程としては、例えば、負極活物質やバインダ、更には必要に応じて導電助剤などを含む混合物（負極合剤）を、適当な溶剤を加えて十分に混練して負極合剤層形成用組成物（スラリー、ペーストなど）を調製し、これを集電体の片面または両面に塗布し、乾燥して前記組成物中の溶剤を除去し、更に必要に応じてカレンダー成形などのプレス処理を施して負極合剤層を形成し、負極を得る工程を採用することができる。   As the negative electrode manufacturing process, for example, a negative electrode active material, a binder, and a mixture (negative electrode mixture) containing a conductive auxiliary agent, if necessary, are sufficiently kneaded with an appropriate solvent, and the negative electrode mixture layer A composition for forming (slurry, paste, etc.) is prepared, applied to one or both sides of a current collector, dried to remove the solvent in the composition, and, if necessary, a press such as calendering A step of forming a negative electrode mixture layer by performing treatment to obtain a negative electrode can be employed.

負極活物質としては、例えば、天然黒鉛（鱗片状黒鉛）、人造黒鉛、膨張黒鉛などの黒鉛材料；ピッチを加熱して得られるコークスなどの易黒鉛化性炭素質材料；フルフリルアルコール樹脂（ＰＦＡ）やポリパラフェニレン（ＰＰＰ）およびフェノール樹脂を低温焼成して得られる非晶質炭素などの難黒鉛化性炭素質材料；などの炭素材料が挙げられる。また、炭素材料の他に、リチウムやリチウム含有化合物も負極活物質として用いることができる。リチウム含有化合物としては、Ｌｉ−Ａｌなどのリチウム合金や、Ｓｉ、Ｓｎなどのリチウムとの合金化が可能な元素を含む合金が挙げられる。更にＳｎ酸化物やＳｉ酸化物などの酸化物系材料も用いることができる。負極合剤全量中における負極活物質量は、例えば、９７〜９９質量％であることが好ましい。   Examples of the negative electrode active material include graphite materials such as natural graphite (flaky graphite), artificial graphite, and expanded graphite; graphitizable carbonaceous materials such as coke obtained by heating a pitch; furfuryl alcohol resin (PFA) ), Polyparaphenylene (PPP), and a non-graphitizable carbonaceous material such as amorphous carbon obtained by baking a phenol resin at a low temperature. In addition to the carbon material, lithium or a lithium-containing compound can also be used as the negative electrode active material. Examples of the lithium-containing compound include lithium alloys such as Li—Al, and alloys containing elements that can be alloyed with lithium such as Si and Sn. Furthermore, oxide-based materials such as Sn oxide and Si oxide can also be used. The amount of the negative electrode active material in the total amount of the negative electrode mixture is preferably 97 to 99% by mass, for example.

導電助剤は、電子伝導性材料であれば特に限定されないし、使用しなくても構わない。導電助剤の具体例としては、アセチレンブラック；ケッチェンブラック；チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックなどのカーボンブラック類；炭素繊維；などの炭素材料の他、金属繊維などの導電性繊維類；フッ化カーボン；銅、ニッケルなどの金属粉末類；ポリフェニレン誘導体などの有機導電性材料；などが挙げられ、これらを１種単独で用いてもよく、２種以上を併用しても構わない。これらの中でも、アセチレンブラック、ケッチェンブラックや炭素繊維が特に好ましい。ただし、負極に導電助剤を使用する場合には、高容量化のために、負極合剤全量中における導電助剤量を１０質量％以下とすることが望ましい。   The conductive aid is not particularly limited as long as it is an electron conductive material, and may not be used. Specific examples of conductive aids include acetylene black; ketjen black; carbon blacks such as channel black, furnace black, lamp black, and thermal black; carbon materials such as carbon fibers; and conductive fibers such as metal fibers. Carbon fluoride, metal powders such as copper and nickel, organic conductive materials such as polyphenylene derivatives, and the like. These may be used alone or in combination of two or more. . Among these, acetylene black, ketjen black and carbon fiber are particularly preferable. However, when a conductive additive is used for the negative electrode, it is desirable that the conductive additive amount in the total amount of the negative electrode mixture be 10% by mass or less in order to increase the capacity.

負極合剤層に係るバインダとしては、熱可塑性樹脂、熱硬化性樹脂のいずれであってもよい。具体的には、例えば、本発明の正極合剤層形成用組成物に用い得るバインダとして先に例示した各種バインダや、スチレンブタジエンゴム（ＳＢＲ）、カルボキシメチルセルロース（ＣＭＣ）、エチレン−アクリル酸共重合体または該共重合体のＮａ＋イオン架橋体、エチレン−メタクリル酸共重合体または該共重合体のＮａ＋イオン架橋体、エチレン−アクリル酸メチル共重合体または該共重合体のＮａ＋イオン架橋体、エチレン−メタクリル酸メチル共重合体または該共重合体のＮａ＋イオン架橋体などが使用でき、それらの材料を１種単独で用いてもよく、２種以上を併用しても構わない。 The binder related to the negative electrode mixture layer may be either a thermoplastic resin or a thermosetting resin. Specifically, for example, various binders exemplified above as binders that can be used in the composition for forming a positive electrode mixture layer of the present invention, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), ethylene-acrylic acid copolymer Copolymer or Na + ion cross-linked product of the copolymer, ethylene-methacrylic acid copolymer or Na + ion cross-linked product of the copolymer, ethylene-methyl acrylate copolymer, or Na + ion cross-linked product of the copolymer Body, ethylene-methyl methacrylate copolymer or Na + ion crosslinked body of the copolymer, etc., and these materials may be used alone or in combination of two or more.

前記の中でも、ＰＶＤＦ、ＳＢＲ、エチレン−アクリル酸共重合体または該共重合体のＮａ＋イオン架橋体、エチレン−メタクリル酸共重合体または該共重合体のＮａ＋イオン架橋体、エチレン−アクリル酸メチル共重合体または該共重合体のＮａ＋イオン架橋体、エチレン−メタクリル酸メチル共重合体または該共重合体のＮａ＋イオン架橋体が特に好ましい。負極合剤全量中におけるバインダ量は、例えば、１〜５質量％であることが好ましい。 Among these, PVDF, SBR, ethylene-acrylic acid copolymer or Na + ion crosslinked product of the copolymer, ethylene-methacrylic acid copolymer or Na + ion crosslinked product of the copolymer, ethylene-acrylic acid A methyl copolymer or a Na + ion crosslinked product of the copolymer, an ethylene-methyl methacrylate copolymer or a Na + ion crosslinked product of the copolymer is particularly preferable. The amount of the binder in the total amount of the negative electrode mixture is preferably 1 to 5% by mass, for example.

負極合剤層の厚み（集電体の両面に負極合剤層が形成されている場合には、その片面あたりの厚み）は、３０〜８０μｍであることが好ましい。   The thickness of the negative electrode mixture layer (when the negative electrode mixture layer is formed on both sides of the current collector, the thickness per one surface thereof) is preferably 30 to 80 μm.

負極に用いる集電体としては、非水電解液二次電池内において、実質上、化学的に安定な電子伝導体であれば特に限定されない。かかる集電体を構成する材料としては、例えば、ステンレス鋼、ニッケルやその合金、銅やその合金、チタンやその合金、炭素、導電性樹脂などの他に、銅またはステンレス鋼の表面にカーボンまたはチタンを処理させたものなどが用いられる。これらの中でも、銅および銅合金が特に好ましい。これらの材料は表面を酸化して用いることもできる。また、表面処理により集電体表面に凹凸を付けることが好ましい。集電体の形状としては、フォイルの他、フィルム、シート、ネット、パンチングされたもの、ラス体、多孔質体、発泡体、繊維群の成形体などが挙げられる。集電体の厚みは特に限定されないが、例えば、５〜５０μｍであることが好ましい。   The current collector used for the negative electrode is not particularly limited as long as it is a substantially chemically stable electronic conductor in the nonaqueous electrolyte secondary battery. Examples of the material constituting the current collector include stainless steel, nickel or an alloy thereof, copper or an alloy thereof, titanium or an alloy thereof, carbon, conductive resin, carbon, or the like on the surface of copper or stainless steel. A material obtained by treating titanium is used. Among these, copper and copper alloys are particularly preferable. These materials can also be used after oxidizing the surface. Moreover, it is preferable to give an unevenness | corrugation to the collector surface by surface treatment. Examples of the shape of the current collector include films, sheets, nets, punched materials, lath bodies, porous bodies, foamed bodies, and molded bodies of fiber groups, in addition to foils. Although the thickness of a collector is not specifically limited, For example, it is preferable that it is 5-50 micrometers.

電極群の製造工程では、例えば、本発明法により調製された正極合剤層形成用組成物を用いて得られた正極と、前記の負極とを、セパレータを介在させつつ重ねて積層電極体としたり、更にこれを渦巻状に巻回し、必要に応じて横断面を扁平状に成形して巻回電極体としたりする。   In the production process of the electrode group, for example, a positive electrode obtained by using the composition for forming a positive electrode mixture layer prepared by the method of the present invention and the negative electrode are stacked with a separator interposed therebetween to form a laminated electrode body. Further, this is wound into a spiral shape, and if necessary, the cross section is formed into a flat shape to form a wound electrode body.

セパレータには、例えば、大きなイオン透過度および所定の機械的強度を有する絶縁性の微多孔性薄膜が用いられる。また、一定温度以上（例えば１００〜１４０℃）で構成材料の溶融によって孔が閉塞し、抵抗を上げる機能を有するもの（すなわち、シャットダウン機能を有するもの）が好ましい。このようなセパレータの具体例としては、耐有機溶剤性および疎水性を有するポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）などポリオレフィン系ポリマー、またはガラス繊維などの材料で構成されるシート（多孔質シート）、不織布若しくは織布；前記例示のポリオレフィン系ポリマーの微粒子を接着剤で固着した多孔質体；などが挙げられる。セパレータの孔径は、正負極より脱離した正負極の活物質、導電助剤および結着剤などが通過しない程度であることが好ましく、例えば、０．０１〜１μｍであることが望ましい。セパレータの厚みは、８〜３０μｍとすることが一般的であるが、本発明では、１０〜２０μｍとすることが好ましい。また、セパレータの空孔率は、構成材料や厚みに応じて決定されるが、３０〜８０％であることが一般的である。   For the separator, for example, an insulating microporous thin film having a large ion permeability and a predetermined mechanical strength is used. Moreover, what has a function which a hole is obstruct | occluded by fusion | melting of a structural material above a fixed temperature (for example, 100-140 degreeC), and raises resistance (namely, what has a shutdown function) is preferable. As a specific example of such a separator, a sheet (porous sheet) composed of a polyolefin-based polymer such as polyethylene (PE) or polypropylene (PP) having organic solvent resistance and hydrophobicity, or a glass fiber, Nonwoven fabric or woven fabric; a porous body in which fine particles of the polyolefin polymer exemplified above are fixed with an adhesive; and the like. The pore diameter of the separator is preferably such that the active material of the positive and negative electrodes, the conductive auxiliary agent, the binder and the like detached from the positive and negative electrodes do not pass through, and is preferably 0.01 to 1 μm, for example. The thickness of the separator is generally 8-30 μm, but is preferably 10-20 μm in the present invention. Further, the porosity of the separator is determined according to the constituent material and thickness, but is generally 30 to 80%.

電池の組み立て工程では、例えば、前記の電極体を外装体内に収容し、非水電解液を注入した後に外装体を封止して、非水電解液二次電池を得る。外装体には、スチール製やアルミニウム（アルミニウム合金）製の筒形（円筒形や角筒形など）の外装缶、金属を蒸着したラミネートフィルムからなるラミネート外装体などを用いることができる。   In the battery assembly process, for example, the electrode body is accommodated in the exterior body, and after the nonaqueous electrolyte is injected, the exterior body is sealed to obtain a nonaqueous electrolyte secondary battery. As the exterior body, a steel or aluminum (aluminum alloy) tubular outer casing (cylindrical or rectangular tubular shape) can be used, or a laminated exterior body made of a metal-deposited laminated film.

非水電解液には、例えば、下記の非水系溶媒中に、リチウム塩を溶解させることで調製した溶液が使用できる。   As the non-aqueous electrolyte, for example, a solution prepared by dissolving a lithium salt in the following non-aqueous solvent can be used.

溶媒としては、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、メチルエチルカーボネート（ＭＥＣ）、γ−ブチロラクトン（γ-
ＢＬ）、１，２−ジメトキシエタン(ＤＭＥ)、テトラヒドロフラン(ＴＨＦ)、２−メチルテトラヒドロフラン、ジメチルスルフォキシド(ＤＭＳＯ)、１，３−ジオキソラン、ホルムアミド、ジメチルホルムアミド(ＤＭＦ)、ジオキソラン、アセトニトリル、ニトロメタン、蟻酸メチル、酢酸メチル、燐酸トリエステル、トリメトキシメタン、ジオキソラン誘導体、スルホラン、３−メチル−２−オキサゾリジノン、プロピレンカーボネート誘導体、テトラヒドロフラン誘導体、ジエチルエーテル、１，３−プロパンサルトンなどの非プロトン性有機溶媒を１種単独で、または２種以上を混合した混合溶媒として用いることができる。 Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), γ-butyrolactone (γ-
BL), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO), 1,3-dioxolane, formamide, dimethylformamide (DMF), dioxolane, acetonitrile, nitromethane , Aprotic such as methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3-propane sultone The organic solvent can be used alone or as a mixed solvent in which two or more are mixed.

非水電解液に係る無機イオン塩としては、例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、Ｌｉ２Ｃ２Ｆ４（ＳＯ３）２、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣｎＦ２ｎ＋１ＳＯ３（ｎ≧２）、ＬｉＮ（ＲｆＯＳＯ２）２［ここでＲｆはフルオロアルキル基］などのリチウム塩から選ばれる少なくとも１種が挙げられる。これらのリチウム塩の非水電解液中の濃度としては、０．６〜１．８ｍｏｌ／ｌとすることが好ましく、０．９〜１．６ｍｏｌ／ｌとすることがより好ましい。 The inorganic ion salt according to the non-aqueous electrolyte solution, for example, LiClO 4, LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2 LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (n ≧ 2), LiN (RfOSO 2 ) 2 [where Rf is a fluoroalkyl group] There may be mentioned at least one selected. The concentration of these lithium salts in the non-aqueous electrolyte is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l.

外装体の有する端子と電極体に係る各電極との電気的な接続や、外装体の封止については、常法に従って行えばよい。   What is necessary is just to perform according to a conventional method about the electrical connection with the terminal which an exterior body has, and each electrode which concerns on an electrode body, and sealing of an exterior body.

図１に、本発明に係る非水電解液二次電池の一例を表す縦断面図を示している。図１に示す非水電解液二次電池は、電池の異常時に作動する電流遮断機構を含む防爆手段を備えた電池の例である。   FIG. 1 is a longitudinal sectional view showing an example of a nonaqueous electrolyte secondary battery according to the present invention. The non-aqueous electrolyte secondary battery shown in FIG. 1 is an example of a battery provided with explosion-proof means including a current interruption mechanism that operates when the battery is abnormal.

図１に示す非水電解液二次電池では、正極１と負極２がセパレータ３を介して渦巻状に巻回され、巻回電極体として非水電解液４と共に電池ケース（外装体）５内に収容されている。なお、図１では、繁雑化を避けるため、正極１や負極２の作製にあたって使用した集電体などは図示していない。   In the non-aqueous electrolyte secondary battery shown in FIG. 1, the positive electrode 1 and the negative electrode 2 are spirally wound via a separator 3, and the battery electrode (exterior body) 5 together with the non-aqueous electrolyte 4 as a wound electrode body. Is housed in. In FIG. 1, in order to avoid complication, a current collector used for manufacturing the positive electrode 1 and the negative electrode 2 is not shown.

電池ケース５（例えばステンレス鋼製）の底部には前記巻回電極体の挿入に先立って、絶縁体６（例えばＰＰ）が配置されている。封口板７（例えばアルミニウム製）は円板状をしていて、その中央部に薄肉部７ａが設けられ、かつ前記薄肉部７ａの周囲に電池内圧を防爆弁９に作用させるための圧力導入口７ｂとしての孔が設けられている。そして、この薄肉部７ａの上面に防爆弁９の突出部９ａが溶接され、溶接部分１１を構成している。なお、前記の封口板７に設けた薄肉部７ａや防爆弁９の突出部９ａなどは、図面上での理解がしやすいように、切断面のみを図示しており、切断面後方の輪郭は図示を省略している。また、封口板７の薄肉部７ａと防爆弁９の突出部９ａの溶接部分１１も、図面上での理解が容易なように、実際よりは誇張した状態に図示している。   An insulator 6 (for example, PP) is disposed on the bottom of the battery case 5 (for example, made of stainless steel) prior to the insertion of the wound electrode body. The sealing plate 7 (for example, made of aluminum) has a disk shape, a thin portion 7a is provided at the center thereof, and a pressure introduction port for allowing the battery internal pressure to act on the explosion-proof valve 9 around the thin portion 7a. A hole 7b is provided. And the protrusion part 9a of the explosion-proof valve 9 is welded to the upper surface of this thin part 7a, and the welding part 11 is comprised. The thin-walled portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are shown only on the cut surface for easy understanding on the drawing, and the contour behind the cut surface is The illustration is omitted. In addition, the welded portion 11 of the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 is also illustrated in an exaggerated state so as to facilitate understanding on the drawing.

端子板８（例えば、表面にニッケルメッキが施された圧延鋼製）は周縁部が鍔状になった帽子状をしており、この端子板８にはガス排出口８ａが設けられている。防爆弁９（例えばアルミニウム製）は円板状をしており、その中央部には発電要素側（図１では、下側）に先端部を有する突出部９ａが設けられ、かつ薄肉部９ｂが設けられ、前記突出部９ａの下面が、前記のように、封口板７の薄肉部７ａの上面に溶接され、溶接部分１１を構成している。絶縁パッキング１０（例えばＰＰ製）は環状をしており、封口板７の周縁部の上部に配置され、その上部に防爆弁９が配置していて、封口板７と防爆弁９とを絶縁するとともに、両者の間から非水電解液が漏れないように両者の間隙を封止している。環状ガスケット１２は例えばＰＰ製で、リード体１３（例えばアルミニウム製）は前記封口板７と正極１とを接続し、巻回電極体の上部には絶縁体１４が配置され、負極２と電池ケース５の底部とはリード体１５（例えばニッケル製）で接続されている。   The terminal plate 8 (for example, made of rolled steel with a nickel plating on the surface) has a hat shape with a peripheral edge portion, and the terminal plate 8 is provided with a gas discharge port 8a. The explosion-proof valve 9 (for example, made of aluminum) has a disk shape, and has a projecting portion 9a having a tip portion on the power generation element side (lower side in FIG. 1) at the center thereof, and a thin-walled portion 9b. As described above, the lower surface of the protruding portion 9a is welded to the upper surface of the thin portion 7a of the sealing plate 7 to constitute the welded portion 11. The insulating packing 10 (for example, made of PP) has an annular shape and is disposed at the upper portion of the peripheral edge of the sealing plate 7, and the explosion-proof valve 9 is disposed on the upper portion thereof, and insulates the sealing plate 7 and the explosion-proof valve 9. At the same time, the gap between the two is sealed so that the non-aqueous electrolyte does not leak from between them. The annular gasket 12 is made of, for example, PP, the lead body 13 (for example, made of aluminum) connects the sealing plate 7 and the positive electrode 1, the insulator 14 is disposed on the upper part of the wound electrode body, the negative electrode 2 and the battery case. 5 is connected with a lead body 15 (for example, made of nickel).

この電池においては、封口板７の薄肉部７ａと防爆弁９の突出部９ａとが溶接部分１１で接触し、防爆弁９の周縁部と端子板８の周縁部とが接触し、正極１と封口板７とは正極側のリード体１３で接続されているので、通常の状態では、正極１と端子板８とはリード体１３、封口板７、防爆弁９およびそれらの溶接部分１１によって電気的接続が得られ、電路として正常に機能する。   In this battery, the thin-walled portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are in contact with each other at the welded portion 11, the peripheral portion of the explosion-proof valve 9 and the peripheral portion of the terminal plate 8 are in contact with each other. Since the positive electrode 1 and the terminal plate 8 are connected to the sealing plate 7 by the positive lead 13, the positive electrode 1 and the terminal plate 8 are electrically connected by the lead 13, the sealing plate 7, the explosion-proof valve 9, and their welded portions 11. Connection is obtained and functions normally as an electrical circuit.

そして、電池が高温にさらされたり、電池が過充電状態になったりするなど、電池に異常事態が起こり、電池内部にガスが発生して電池の内圧が上昇した場合には、その内圧上昇により、防爆手段が以下のように作動して、電池の破裂を防止することができるように設計されている。まず、電流遮断機構が、防爆弁９の中央部が内圧方向（図１では、上側の方向）に変形し、それに伴って溶接部分１１で一体化されている薄肉部７ａに剪断力が働いて該薄肉部７ａが破断するか、または防爆弁９の突出部９ａと封口板７の薄肉部７ａとの溶接部分１１が剥離することで作動して電流が遮断され、続いて、この防爆弁９に設けられている薄肉部９ｂが開裂することでガスを端子板８のガス排出口８ａから電池外部に排出させる。   If an abnormal situation occurs in the battery, such as when the battery is exposed to a high temperature or the battery is overcharged, and the internal pressure of the battery rises due to the generation of gas inside the battery, the internal pressure rises. The explosion-proof means operates as follows and is designed to prevent the battery from bursting. First, the current interruption mechanism is such that the central portion of the explosion-proof valve 9 is deformed in the internal pressure direction (upward direction in FIG. 1), and accordingly, a shearing force is applied to the thin portion 7a integrated in the welded portion 11. When the thin-walled portion 7a is broken or the welded portion 11 between the projecting portion 9a of the explosion-proof valve 9 and the thin-walled portion 7a of the sealing plate 7 is peeled off, the current is cut off, and then the explosion-proof valve 9 When the thin-walled portion 9b provided on the base plate is cleaved, the gas is discharged from the gas discharge port 8a of the terminal plate 8 to the outside of the battery.

なお、本発明に係る非水電解液二次電池は、正極合剤層中にＬｉ２ＣＯ３を含有しているが、例えば電池が過充電状態になることによって、このＬｉ２ＣＯ３がガス化し、電池の電流遮断機構の作動を促すため、電池内での電流が早期に遮断される。よって、本発明に係る非水電解液二次電池は、高い安全性を有するものとなる。 In addition, although the nonaqueous electrolyte secondary battery according to the present invention contains Li 2 CO 3 in the positive electrode mixture layer, for example, when the battery is overcharged, the Li 2 CO 3 becomes a gas. In order to facilitate the operation of the battery current interrupting mechanism, the current in the battery is interrupted early. Therefore, the non-aqueous electrolyte secondary battery according to the present invention has high safety.

本発明法により製造される非水電解液二次電池は、従来から知られている非水電解液二次電池と同様の用途に用いることができる。   The nonaqueous electrolyte secondary battery produced by the method of the present invention can be used for the same applications as conventionally known nonaqueous electrolyte secondary batteries.

以下、実施例に基づいて本発明を詳細に述べる。ただし、下記実施例は、本発明を制限するものではない。   Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

実施例１
＜正極合剤層形成用組成物の調製＞
（混合工程）
正極活物質である化合物（Ａ）：ＬｉＮｉ０．５Ｃｏ０．１７Ｍｎ０．３Ｍｇ０．０３Ｏ２と化合物（Ｂ）：ＬｉＣｏ０．９９７Ａｌ０．００３Ｏ２とを、（Ａ）／（Ｂ）＝３０／７０の質量割合で含む混合物１００質量部と、結着剤であるＰＶＤＦを１０質量％の濃度で含むＮＭＰ溶液２０質量部と、導電助剤である人造黒鉛１質量部およびケッチェンブラック１質量部とを、プラネタリーミキサーを用いて炭酸ガスを導入した系内で混練した。ここに、更にＮＭＰを加えて粘度を調節して、正極合剤層形成用組成物を調製した。 Example 1
<Preparation of composition for forming positive electrode mixture layer>
(Mixing process)
Compound (A) as a positive electrode active material: LiNi 0.5 Co 0.17 Mn 0.3 Mg 0.03 O 2 and compound (B): LiCo 0.997 Al 0.003 O 2 / (B) = 100 parts by weight of a mixture containing 30/70 by weight, 20 parts by weight of an NMP solution containing 10% by weight of PVDF as a binder, and 1 part by weight of artificial graphite as a conductive aid Then, 1 part by mass of ketjen black was kneaded in a system into which carbon dioxide gas was introduced using a planetary mixer. Here, NMP was further added to adjust the viscosity to prepare a composition for forming a positive electrode mixture layer.

（保管工程）
混練後の正極合剤層形成用組成物を容器に移し、この容器内に炭酸ガスを導入し、正極合剤層形成用組成物が沈降しないようにボールミル回転架台を用いて１２時間保管した。 (Storage process)
The composition for forming a positive electrode mixture layer after kneading was transferred to a container, carbon dioxide gas was introduced into the container, and stored for 12 hours using a ball mill rotating mount so that the composition for forming a positive electrode mixture layer did not settle.

＜正極の作製＞
保管工程後の正極合剤層形成用組成物を、７０メッシュの厚みを通過させて粗大なものを除去した後、厚みが１２μｍのアルミニウム箔からなる正極集電体の両面に均一に塗布して乾燥し、更にプレス処理を行って、集電体の両面に、厚み（集電体の片面あたりの厚み）が６５μｍの正極合剤層を有する正極を作製した。 <Preparation of positive electrode>
The composition for forming a positive electrode mixture layer after the storage step is passed through a thickness of 70 mesh to remove coarse particles, and then uniformly applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 12 μm. After drying, press treatment was performed to prepare a positive electrode having a positive electrode mixture layer having a thickness (thickness per one surface of the current collector) of 65 μm on both sides of the current collector.

＜負極の作製＞
天然黒鉛：９７．５質量％、ＳＢＲ：１．５質量％、およびＣＭＣ（増粘剤）：１質量％を、水を用いて混合して負極合剤層形成用スラリーを調製した。この負極合剤層形成用スラリーを、集電体である銅箔（厚み：８μｍ）の両面に塗布し、１２０℃で１２時間真空乾燥を施し、更にプレス処理を施して、集電体の両面に、厚み（集電体の片面あたりの厚み）が７０μｍの負極合剤層を有する負極を作製した。 <Production of negative electrode>
Natural graphite: 97.5 mass%, SBR: 1.5 mass%, and CMC (thickener): 1 mass% were mixed with water to prepare a slurry for forming a negative electrode mixture layer. This negative electrode mixture layer forming slurry was applied to both sides of a copper foil (thickness: 8 μm) as a current collector, vacuum-dried at 120 ° C. for 12 hours, and further subjected to a press treatment to obtain both sides of the current collector. In addition, a negative electrode having a negative electrode mixture layer having a thickness (thickness per one side of the current collector) of 70 μm was prepared.

＜電極体の作製＞
前記の正極と負極とをセパレータ（厚みが１４μｍで、透気度が３００秒／１００ｃｍ３のポリエチレン製多孔膜）を介して重ね合わせ、渦巻状に巻回して巻回電極体を作製した。 <Production of electrode body>
The positive electrode and the negative electrode were overlapped via a separator (a polyethylene porous film having a thickness of 14 μm and an air permeability of 300 seconds / 100 cm 3), and wound in a spiral shape to produce a wound electrode body.

＜非水電解液の調製＞
メチルエチルカーボネートとジエチルカーボネートとエチレンカーボネートとの混合溶媒（体積比が２：１：３）に、１．２ｍｏｌ／ｌの濃度でＬｉＰＦ６を溶解し、これに２質量％となる量のビニレンカーボネート（ＶＣ）２質量％と、１質量％となる量のビニルエチレンカーボネート（Ｖ−ＥＣ）とを加えて非水電解液を調製した。 <Preparation of non-aqueous electrolyte>
LiPF 6 is dissolved at a concentration of 1.2 mol / l in a mixed solvent of methyl ethyl carbonate, diethyl carbonate, and ethylene carbonate (volume ratio is 2: 1: 3), and vinylene carbonate in an amount of 2% by mass is dissolved therein. (VC) 2% by mass and vinyl ethylene carbonate (V-EC) in an amount of 1% by mass were added to prepare a non-aqueous electrolyte.

＜電池の組み立て＞
前記の巻回電極体を円筒形の電池ケースに挿入し、前記非水電解液を注入した後、封止して、図１に示す構造の非水電解液二次電池を作製した。 <Battery assembly>
The wound electrode body was inserted into a cylindrical battery case, the nonaqueous electrolyte solution was injected, and then sealed to produce a nonaqueous electrolyte secondary battery having the structure shown in FIG.

実施例２
実施例１と同じ混合工程によって調製した正極合剤層形成用組成物を容器に移し、炭酸ガスを容器内に導入しなかった以外は、実施例１と同様にして１２時間保管した。その後、正極活物質中のＬｉＯＨ量に対してモル基準で同等以上の炭酸ガスを容器内に導入し、更に１２時間保管して、保管工程を完了した。 Example 2
The positive electrode mixture layer forming composition prepared by the same mixing step as in Example 1 was transferred to a container and stored for 12 hours in the same manner as in Example 1 except that carbon dioxide was not introduced into the container. Thereafter, carbon dioxide equivalent to or higher than the amount of LiOH in the positive electrode active material was introduced into the container and stored for 12 hours to complete the storage process.

そして、前記の保管工程を経た正極合剤層形成用組成物を用いた以外は、実施例１と同様にして正極を作製し、この正極を用いた以外は、実施例１と同様にして非水電解液二次電池を作製した。   Then, a positive electrode was produced in the same manner as in Example 1 except that the positive electrode mixture layer forming composition that had been subjected to the above storage process was used, and the same procedure as in Example 1 was carried out except that this positive electrode was used. A water electrolyte secondary battery was produced.

実施例３
混練系内に炭酸ガスを導入しなかった以外は、実施例１と同じ混合工程によって正極合剤層形成用組成物を調製し、これを実施例１と同じ保管工程によって保管した。 Example 3
A composition for forming a positive electrode mixture layer was prepared by the same mixing step as in Example 1 except that carbon dioxide was not introduced into the kneading system, and was stored in the same storage step as in Example 1.

そして、前記の保管工程を経た正極合剤層形成用組成物を用いた以外は、実施例１と同様にして正極を作製し、この正極を用いた以外は、実施例１と同様にして非水電解液二次電池を作製した。   Then, a positive electrode was produced in the same manner as in Example 1 except that the positive electrode mixture layer forming composition that had been subjected to the above storage process was used, and the same procedure as in Example 1 was carried out except that this positive electrode was used. A water electrolyte secondary battery was produced.

比較例１
実施例１と同じ混合工程によって調製した正極合剤含有組成物を容器に移し、炭酸ガスを容器内に導入しなかった以外は、実施例１と同様にして１２時間保管して保管工程を完了した。 Comparative Example 1
The positive electrode mixture-containing composition prepared by the same mixing process as in Example 1 was transferred to a container, and stored for 12 hours in the same manner as in Example 1 except that carbon dioxide was not introduced into the container to complete the storage process. did.

そして、前記の保管工程を経た正極合剤層形成用組成物を用いた以外は、実施例１と同様にして正極を作製し、この正極を用いた以外は、実施例１と同様にして非水電解液二次電池を作製した。   Then, a positive electrode was produced in the same manner as in Example 1 except that the positive electrode mixture layer forming composition that had been subjected to the above storage process was used, and the same procedure as in Example 1 was carried out except that this positive electrode was used. A water electrolyte secondary battery was produced.

比較例２
混練系内に炭酸ガスを導入しなかった以外は、実施例１と同じ混合工程によって調製した正極合剤層形成用組成物を容器に移し、炭酸ガスを容器内に導入しなかった以外は、実施例１と同様にして１２時間保管して保管工程を完了した。 Comparative Example 2
Except that the carbon dioxide gas was not introduced into the kneading system, the positive electrode mixture layer forming composition prepared by the same mixing step as in Example 1 was transferred to the container, and the carbon dioxide gas was not introduced into the container. The storage process was completed by storing for 12 hours in the same manner as in Example 1.

そして、前記の保管工程を経た正極合剤層形成用組成物を用いた以外は、実施例１と同様にして正極を作製し、この正極を用いた以外は、実施例１と同様にして非水電解液二次電池を作製した。   Then, a positive electrode was produced in the same manner as in Example 1 except that the positive electrode mixture layer forming composition that had been subjected to the above storage process was used, and the same procedure as in Example 1 was carried out except that this positive electrode was used. A water electrolyte secondary battery was produced.

実施例１〜３および比較例１、２の非水電解液二次電池を、以下の方法で評価した。   The nonaqueous electrolyte secondary batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated by the following methods.

＜生産性の評価＞
実施例１〜３および比較例１、２の非水電解液二次電池に係る正極を、前記の方法で１００個ずつ作製した際に、正極合剤層形成用組成物を集電体に良好に塗布できたものの個数を調べた。 <Evaluation of productivity>
When 100 positive electrodes according to the non-aqueous electrolyte secondary batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were produced by the above method, the positive electrode mixture layer forming composition was good as a current collector. The number of those that could be applied to was examined.

＜安全性の評価＞
実施例および比較例の各電池を、あらかじめ１００％充電状態にしてから過充電試験を行い、その特性を評価した。過充電試験は、１８Ｖの電源を用い、各電池に１５００ｍＡ（１Ｃ）の電流を強制的に流し続けるという通常では起こらない異常動作を想定して行い、その時の内圧上昇に伴う電流遮断機構（安全機構）が作動するまでの時期、および電池の到達する最高温度を測定した。 <Evaluation of safety>
Each battery of the example and the comparative example was charged to 100% in advance and then an overcharge test was performed to evaluate the characteristics. The overcharge test is performed assuming an abnormal operation that does not occur normally, using an 18V power supply and forcing a current of 1500mA (1C) to flow through each battery. The time until the mechanism) was activated and the maximum temperature reached by the battery were measured.

前記の各評価結果を、正極合剤層形成用組成物の混合工程および保管工程での炭酸ガスの導入状況と併せて表１に示す。なお、表１では、各工程で炭酸ガスの導入があった場合を「○」で示し、炭酸ガスの導入がなかった場合を「×」で示す。また、表１では、「生産性の評価」の欄に、正極を１００個作製した際に、正極合剤層形成用組成物を集電体に良好に塗布できたものの個数を示す。   Each evaluation result is shown in Table 1 together with the introduction status of carbon dioxide in the mixing step and the storage step of the positive electrode mixture layer forming composition. In Table 1, the case where carbon dioxide was introduced in each step is indicated by “◯”, and the case where carbon dioxide was not introduced is indicated by “x”. In Table 1, the column “Evaluation of productivity” shows the number of the positive electrode mixture layer forming compositions that were successfully applied to the current collector when 100 positive electrodes were produced.

Figure 2013073779
Figure 2013073779

実施例１〜３の非水電解液二次電池の正極の作製に使用した正極合剤層形成用組成物は、保管工程後の増粘が抑えられており、表１に示す通り、集電体への塗布性が良好で、正極および非水電解液二次電池の生産性が良好であった。   The composition for forming a positive electrode mixture layer used for the preparation of the positive electrodes of the nonaqueous electrolyte secondary batteries of Examples 1 to 3 has suppressed thickening after the storage step. The applicability to the body was good, and the productivity of the positive electrode and the nonaqueous electrolyte secondary battery was good.

これに対し、比較例１、２の非水電解液二次電池の正極の作製に使用した正極合剤層形成用組成物は、保管工程後に増粘が認められ、表１に示す通り、集電体への塗布性が、実施例１〜３に係る正極合剤含有組成物に比べて大きく損なわれており、正極および非水電解液二次電池の生産性が劣っていた。   On the other hand, the composition for forming a positive electrode mixture layer used for preparing the positive electrodes of the nonaqueous electrolyte secondary batteries of Comparative Examples 1 and 2 was found to have increased viscosity after the storage step. The applicability to the electric conductor was greatly impaired as compared with the positive electrode mixture-containing compositions according to Examples 1 to 3, and the productivity of the positive electrode and the nonaqueous electrolyte secondary battery was inferior.

また、表１に示す通り、実施例１〜３の非水電解液二次電池は、過充電試験時において、比較例の電池に比べて電流遮断機構の作動時間が短く、かつ電池の最高到達温度が低く、安全性がより優れている。これは、実施例１〜３の電池では、保管工程のいずれかの段階で炭酸ガスを導入した正極合剤含有組成物を使用して作製した正極を有しているため、正極合剤層が、電池の安全性を高め得る量のＬｉ２ＣＯ３を含有しているためであると推測される。 In addition, as shown in Table 1, the nonaqueous electrolyte secondary batteries of Examples 1 to 3 had a shorter operating time of the current interruption mechanism than the battery of the comparative example during the overcharge test, and reached the highest level of the battery. Low temperature and better safety. This is because the batteries of Examples 1 to 3 have a positive electrode prepared using a positive electrode mixture-containing composition into which carbon dioxide gas was introduced at any stage of the storage process. This is presumably because it contains an amount of Li 2 CO 3 that can improve the safety of the battery.

１ 正極
２ 負極
３ セパレータ 1 Positive electrode 2 Negative electrode 3 Separator

Claims (6)

正極活物質、導電助剤、バインダおよび溶剤を含有し、非水電解液二次電池用の正極の正極合剤層を形成するための組成物を調製する方法であって、
前記正極活物質、前記導電助剤、前記バインダおよび前記溶剤を混合する混合工程と、
前記混合工程により得られた混合物を容器に収容して保管する保管工程とを少なくとも有しており、
前記正極活物質にリチウムニッケル含有複合酸化物を使用し、前記溶剤に有機溶剤を使用し、かつ前記バインダに前記有機溶剤に溶解し得るバインダを使用し、
前記保管工程中に、前記容器内に炭酸ガスを導入することを特徴とする正極合剤層形成用組成物の調製方法。 A method for preparing a composition for forming a positive electrode mixture layer of a positive electrode for a non-aqueous electrolyte secondary battery, comprising a positive electrode active material, a conductive additive, a binder and a solvent,
A mixing step of mixing the positive electrode active material, the conductive additive, the binder and the solvent;
And at least a storage step of storing and storing the mixture obtained in the mixing step in a container,
Using a lithium nickel-containing composite oxide for the positive electrode active material, using an organic solvent for the solvent, and using a binder that can be dissolved in the organic solvent for the binder,
A method for preparing a composition for forming a positive electrode mixture layer, wherein carbon dioxide gas is introduced into the container during the storage step. 混合工程において、炭酸ガスを導入した系内で正極活物質、導電助剤、バインダおよび溶剤を混合する請求項1に記載の正極合剤層形成用組成物の調製方法。   2. The method for preparing a composition for forming a positive electrode mixture layer according to claim 1, wherein in the mixing step, the positive electrode active material, the conductive additive, the binder and the solvent are mixed in a system into which carbon dioxide gas has been introduced. 正極活物質の少なくとも一部に、一般式ＬｉＮｉｘＣｏ（１−ｘ−ｙ−ｚ）ＭｎｙＭ１ ｚＯ２（０．５≦ｘ≦０．９、０≦ｙ≦０．３、０．００３≦ｚ≦０．０５であり、元素Ｍ１はＬｉ、Ｎｉ、ＣｏおよびＭｎ以外の金属元素であって、Ｍｇ、Ａｌ、Ｔｉ、Ｓｒ、Ｚｒ、Ｎｂ、ＡｇおよびＢａよりなる群から選択される少なくとも１種の元素を含む）で表される層状リチウムニッケルコバルト複合酸化物（Ａ）を使用する請求項１または２に記載の正極合剤層形成用組成物の調製方法。 At least a portion of the positive electrode active material, the general formula LiNi x Co (1-x- y-z) Mn y M 1 z O 2 (0.5 ≦ x ≦ 0.9,0 ≦ y ≦ 0.3,0 0.003 ≦ z ≦ 0.05, and the element M 1 is a metal element other than Li, Ni, Co, and Mn, and is selected from the group consisting of Mg, Al, Ti, Sr, Zr, Nb, Ag, and Ba The method for preparing a composition for forming a positive electrode mixture layer according to claim 1 or 2, wherein the layered lithium nickel cobalt composite oxide (A) represented by (including at least one kind of element) is used. 正極活物質に、一般式ＬｉＮｉａＣｏ（１−ａ−ｂ−ｃ）ＭｎｂＭ２ ｃＯ２（０≦ａ≦０．０３、０≦ｂ≦０．０２、０．００３≦ｃ≦０．０１であり、元素Ｍ２はＬｉ、Ｎｉ、ＣｏおよびＭｎ以外の金属元素であって、Ｍｇ、Ａｌ、Ｔｉ、Ｓｒ、Ｚｒ、Ｎｂ、ＡｇおよびＢａよりなる群から選択される少なくとも１種の元素を含む）で表される層状リチウムコバルト複合酸化物（Ｂ）を、層状リチウムニッケルコバルト複合酸化物（Ａ）とともに使用する請求項３に記載の正極合剤層形成用組成物の調製方法。 For the positive electrode active material, the general formula LiNi a Co (1- abc ) Mn b M 2 c O 2 (0 ≦ a ≦ 0.03, 0 ≦ b ≦ 0.02, 0.003 ≦ c ≦ 0) 0.01, and the element M 2 is a metal element other than Li, Ni, Co, and Mn, and is at least one selected from the group consisting of Mg, Al, Ti, Sr, Zr, Nb, Ag, and Ba The method for preparing a composition for forming a positive electrode mixture layer according to claim 3, wherein the layered lithium cobalt composite oxide (B) represented by (including an element) is used together with the layered lithium nickel cobalt composite oxide (A). バインダにポリフッ化ビニリデンを使用する請求項１〜４のいずれかに記載の正極合剤層形成用組成物の調製方法。   The method for preparing a composition for forming a positive electrode mixture layer according to any one of claims 1 to 4, wherein polyvinylidene fluoride is used for the binder. 正極、負極、セパレータおよび非水電解液を有する非水電解液二次電池の製造方法であって、
集電体の片面または両面に、請求項１〜５のいずれかに記載の正極合剤層形成用組成物の調製方法により得られた正極合剤層形成用組成物を塗布する工程を経て正極合剤層を形成した正極を用いることを特徴とする非水電解液二次電池の製造方法。 A method for producing a non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte,
A positive electrode through a step of applying a positive electrode mixture layer forming composition obtained by the method for preparing a positive electrode mixture layer forming composition according to any one of claims 1 to 5 on one or both surfaces of a current collector A method for producing a nonaqueous electrolyte secondary battery, comprising using a positive electrode on which a mixture layer is formed.
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