JP2007134276A - Negative electrode for lithium-ion secondary battery, method of manufacturing same, and lithium-ion secondary battery - Google Patents

Negative electrode for lithium-ion secondary battery, method of manufacturing same, and lithium-ion secondary battery Download PDF

Info

Publication number
JP2007134276A
JP2007134276A JP2005328658A JP2005328658A JP2007134276A JP 2007134276 A JP2007134276 A JP 2007134276A JP 2005328658 A JP2005328658 A JP 2005328658A JP 2005328658 A JP2005328658 A JP 2005328658A JP 2007134276 A JP2007134276 A JP 2007134276A
Authority
JP
Japan
Prior art keywords
negative electrode
secondary battery
ion secondary
electrode mixture
lithium ion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2005328658A
Other languages
Japanese (ja)
Other versions
JP5172089B2 (en
Inventor
Minoru Sakai
稔 酒井
Katsuhiro Nagayama
勝博 長山
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Chemical Corp
Original Assignee
JFE Chemical Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by JFE Chemical Corp filed Critical JFE Chemical Corp
Priority to JP2005328658A priority Critical patent/JP5172089B2/en
Publication of JP2007134276A publication Critical patent/JP2007134276A/en
Application granted granted Critical
Publication of JP5172089B2 publication Critical patent/JP5172089B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

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

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a negative electrode for a lithium-ion secondary battery wherein cycle characteristics is not easily deteriorated even if discharge capacity is enhanced by applying a pressure to the lithium-ion secondary battery negative electrode having a granular carbon material to increase electrode density. <P>SOLUTION: The method has a negative electrode mixture preparing process to prepare a negative electrode mixture containing a mesocarbon microsphere graphitized article and a graphite particle having a particle diameter smaller than the article, a negative electrode forming process to form an electrode plate having a layer comprising the negative electrode mixture by sticking the negative electrode mixture to the electrode plate, and a pressurizing process to apply the pressure for setting density of the layer at 1.8 g/cm<SP>3</SP>and the aspect ratio of the mesocarbon microsphere graphitized article at 1.4 or less to the layer comprising the negative electrode mixture. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、リチウムイオン二次電池用負極およびその製造方法ならびにリチウムイオン二次電池に関する。   The present invention relates to a negative electrode for a lithium ion secondary battery, a method for producing the same, and a lithium ion secondary battery.

リチウムイオン二次電池は、作動電圧が高いこと、電池容量が大きいこと、およびサイクル寿命が長い等の優れた特徴を有し、かつ環境汚染が少ないことから、従来主流であったニッケル・カドミウム電池やニッケル水素電池に代わって広範囲で用いられている。   Lithium-ion secondary batteries have excellent characteristics such as high operating voltage, large battery capacity, long cycle life, and low environmental pollution. It is widely used in place of nickel-metal hydride batteries.

リチウムイオン二次電池が実用可能となったのは、負極材として安全性に問題があったリチウム金属に代わり、リチウムイオンを層間挿入した炭素材料が安定した活物質となり得ることが発見され、リチウムイオン二次電池の実用化と性能向上に果たす炭素材料の役割が認識されたことに起因する。   Lithium ion secondary batteries have become practical because it was discovered that carbon materials with intercalated lithium ions could be a stable active material instead of lithium metal, which had a safety problem as a negative electrode material. This is due to the recognition of the role of carbon materials in the practical application and performance improvement of ion secondary batteries.

このようなリチウムイオン二次電池は、近年の携帯電話やノートパソコン等の携帯電子機器の高性能、高機能化による消費電力増加に伴い、高容量化が求められている。
これに関連した従来法として、例えば次に示す特許文献１、２に記載の非水電解液二次電池を挙げることができる。 Such lithium ion secondary batteries are required to have higher capacities as power consumption increases due to higher performance and higher functionality of portable electronic devices such as mobile phones and notebook personal computers in recent years.
As a conventional method related to this, for example, the following non-aqueous electrolyte secondary batteries described in Patent Documents 1 and 2 can be cited.

特許文献１には、リチウム含有複合酸化物からなる正極と、非水電解液と、再充電可能な負極とを備えた非水電解液二次電池において、前記負極は光学的に異方性で単一の相を持った球状粒子からなる黒鉛材料と、それより平均粒径の小さな他の異なる黒鉛微粉末とで構成された複合炭素材であることを特徴とする非水電解液二次電池が記載されている。
そして、このような非水電解液二次電池は、従来、得ることができなかった高電圧、高容量を有し、さらに、充放電に伴い黒鉛のＣ軸方向の膨張及び収縮が大きいために成形体が膨張し、元の形状を維持できなくなり、負極合剤粒子間の導電性の低下等を引き起こし充放電サイクル特性の劣化をもたらすという従来の課題を解決すると記載されている。つまり、このような非水電解液二次電池は、充放電に伴う成形体の膨潤、崩れから生じる負極合剤粒子間の導電性の低下を防いだものであると記載されている。 In Patent Document 1, in a non-aqueous electrolyte secondary battery including a positive electrode made of a lithium-containing composite oxide, a non-aqueous electrolyte, and a rechargeable negative electrode, the negative electrode is optically anisotropic. Non-aqueous electrolyte secondary battery characterized by being a composite carbon material composed of a graphite material composed of spherical particles having a single phase and other different fine graphite powders having a smaller average particle size Is described.
Such a non-aqueous electrolyte secondary battery has a high voltage and a high capacity that could not be obtained conventionally, and further, due to the large expansion and contraction of graphite in the C-axis direction due to charge and discharge. It is described that the molded body expands and the original shape cannot be maintained, which causes a decrease in conductivity between the negative electrode mixture particles and the like, resulting in deterioration of charge / discharge cycle characteristics. That is, it is described that such a non-aqueous electrolyte secondary battery prevents the decrease in conductivity between the negative electrode mixture particles caused by swelling and collapse of the molded body accompanying charge and discharge.

さらに、特許文献１には、球状粒子からなる黒鉛材料と、黒鉛微粉末との混合比が重要であり、上記複合炭素材における黒鉛微粉末の添加量は、球状粒子からなる黒鉛材料に対して、２０重量％以下が良く、２０重量％を超えた場合は球状粒子からなる黒鉛材料の充填密度が減少して電池としての容量が低下すると記載されている。   Further, in Patent Document 1, the mixing ratio of graphite material composed of spherical particles and graphite fine powder is important, and the amount of graphite fine powder added to the composite carbon material is larger than that of graphite material composed of spherical particles. It is described that 20% by weight or less is good, and if it exceeds 20% by weight, the packing density of the graphite material made of spherical particles is reduced and the capacity as a battery is reduced.

また、特許文献２には、リチウム含有酸化物を活物質とする正極と、非水電解液と、炭素材料を活物質とした負極とを備えた非水電解液二次電池において、前記炭素材料は粒径が１０μｍ以下でかつ比表面積が１５ｍ２／ｇ以下の鱗状炭素材料と、粒径１０μｍ以下でかつ比表面積が７ｍ２／ｇ以下のビーズ状炭素材料との混合物であることを特徴とする、非水電解液二次電池が記載されている。
そしてこのような非水電解液二次電池は、従来、黒鉛層間化合物を負極として用いた場合にＬｉの黒鉛層間への挿入、脱離によって、黒鉛が膨張収縮を起こし、電極構造が徐々に崩壊し、良好な充放電サイクル特性を得られなかったという課題を解決するものであり、鱗状炭素材料とビーズ状炭素材料とを混合するので、鱗状炭素材料の隙間にビーズ状炭素材料が充填され、炭素材料の充填密度の低下を抑えながら電極構造を柔軟にでき、高容量で充放電サイクル特性に優れた電池であると記載されている。
特開平０７−３７６１８号公報 特開平０９−２４５７８９号公報 Patent Document 2 discloses a nonaqueous electrolyte secondary battery including a positive electrode using a lithium-containing oxide as an active material, a nonaqueous electrolyte, and a negative electrode using a carbon material as an active material. and wherein the particle size is a mixture of the following and scaly carbon material and a specific surface area below 15 m 2 / g in 10 [mu] m, and a specific surface area particle size 10 [mu] m or less and 7m 2 / g or less of beaded carbon material A non-aqueous electrolyte secondary battery is described.
In such a non-aqueous electrolyte secondary battery, when a graphite intercalation compound is used as a negative electrode, the graphite expands and contracts due to the insertion and removal of Li from the graphite layer, and the electrode structure gradually collapses. In order to solve the problem that good charge / discharge cycle characteristics could not be obtained, since the scaly carbon material and the beaded carbon material are mixed, the beaded carbon material is filled in the gap between the scaly carbon materials, It is described that the battery can be made flexible while suppressing a decrease in packing density of the carbon material, and has a high capacity and excellent charge / discharge cycle characteristics.
Japanese Patent Laid-Open No. 07-37618 JP 09-245789 A

本発明者は、このようなリチウムイオン二次電池をさらに高容量化することを目的に研究開発を行った。そして、粒状の炭素材料を有する負極に圧力を加え、その粒状の炭素材料の充填率（電極密度）を増大させると、負極の体積当りの放電容量を向上させることができることを見出した。しかし、この場合、サイクル特性が悪化することがあった。そこで、さらに研究開発を推し進め、負極に圧力を加え電極密度を増大させ負極の体積当りの放電容量を向上させても、サイクル特性が悪化し難いリチウムイオン二次電池負極に製造方法を見出し、本発明に至った。   The present inventor conducted research and development for the purpose of further increasing the capacity of such a lithium ion secondary battery. And it discovered that the discharge capacity per volume of a negative electrode could be improved by applying a pressure to the negative electrode which has a granular carbon material, and increasing the filling rate (electrode density) of the granular carbon material. However, in this case, the cycle characteristics may be deteriorated. Therefore, further research and development was carried out, and even when pressure was applied to the negative electrode to increase the electrode density and improve the discharge capacity per unit volume of the negative electrode, a manufacturing method was found for a negative electrode for a lithium ion secondary battery in which cycle characteristics are unlikely to deteriorate. Invented.

つまり、本発明の目的は、従来のリチウムイオン二次電池よりもさらに高容量化しており、加えてサイクル特性が従来と同等以上に高位であるリチウムイオン二次電池負極の製造方法を提供することにある。
また、従来と比較してサイクル特性は同程度に維持されたまま、負極の体積当りの放電容量が向上したリチウムイオン二次電池負極を提供することにある。 That is, the object of the present invention is to provide a method for producing a negative electrode for a lithium ion secondary battery that has a higher capacity than that of a conventional lithium ion secondary battery and that has a cycle characteristic that is higher than that of the conventional one. It is in.
Another object of the present invention is to provide a negative electrode for a lithium ion secondary battery in which the discharge capacity per unit volume of the negative electrode is improved while the cycle characteristics are maintained at the same level as before.

本発明者は、上記のように粒状の炭素材料を有する負極に圧力を加えたときに、サイクル特性が悪化する原因を検討した。そして、その原因を次のように考えた。
粒状の炭素材料を有する負極に圧力を加えると、この粒状の炭素材料はその圧力が加わった方向に対して垂直方向に広がるように変形する。するとこの負極を使用した場合に、Ｌｉイオンの出入りに伴う粒状の炭素材料の膨張収縮変化量が、変形していない略球形の粒状の炭素材料を有する場合と比較して増大する。このように膨張収縮変化量が増大すれば、粒状の炭素材料を有する負極は崩壊しやすくなるので、サイクル特性が悪化する。 The present inventor examined the cause of deterioration of cycle characteristics when pressure was applied to the negative electrode having a granular carbon material as described above. And the cause was considered as follows.
When pressure is applied to a negative electrode having a granular carbon material, the granular carbon material is deformed so as to spread in a direction perpendicular to the direction in which the pressure is applied. Then, when this negative electrode is used, the amount of expansion / contraction change of the granular carbon material accompanying the entry / exit of Li ions is increased as compared with the case of having a substantially spherical granular carbon material that is not deformed. If the amount of expansion / contraction change increases in this way, the negative electrode having a granular carbon material tends to collapse, and the cycle characteristics deteriorate.

そして、本発明者は、メソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを電極板上に付けて負極とし、これに特定の圧力を加え、負極中で大きな体積を専有するメソカーボン小球体黒鉛化品のアスペクト比を１．４以下とすることにより、電極密度が１．８ｇ／ｃｍ３以上に増大しても負極体積当りの放電容量が向上して、かつ、サイクル特性が悪化し難いことを見出した。 Then, the present inventor attaches a specific pressure to the mesocarbon microsphere graphitized product and graphite particles having an average particle size smaller than this on the electrode plate, and applies a specific pressure to the negative electrode. By setting the aspect ratio of the mesocarbon microsphere graphitized product having a volume to 1.4 or less, the discharge capacity per negative electrode volume is improved even when the electrode density is increased to 1.8 g / cm 3 or more. And it discovered that cycling characteristics did not deteriorate easily.

すなわち、本発明は次の（１）〜（６）を提供するものである。
（１）リチウムイオン二次電池負極の製造方法であって、メソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤を調製する負極合剤調整工程と、前記負極合剤を電極板に付け、前記負極合剤からなる層を有する電極板を形成する負極形成工程と、前記負極合剤からなる層に、この層の密度を１．８ｇ／ｃｍ３以上とし、かつ、この層中の前記メソカーボン小球体黒鉛化品のアスペクト比を１．４以下とする圧力を加える加圧工程とを具備するリチウムイオン二次電池負極の製造方法。
（２）前記負極合剤において、前記メソカーボン小球体黒鉛化品と前記黒鉛質粒子との合計質量に対する、前記メソカーボン小球体黒鉛化品の質量割合が、２５質量％超、７５質量％以下である、上記（１）に記載のリチウムイオン二次電池負極の製造方法。
（３）前記黒鉛質粒子が非燐片状黒鉛質粒子である上記（１）または（２）に記載のリチウムイオン二次電池負極の製造方法。
（４）前記メソカーボン小球体黒鉛化品の平均粒径が５〜１００μｍであり、前記黒鉛質粒子の平均粒径が１〜３０μｍである上記（１）〜（３）のいずれかに記載のリチウムイオン二次電池負極の製造方法。
（５）アスペクト比が１．４以下であるメソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤からなり、密度が１．８ｇ／ｃｍ３以上である層を電極板上に有する、リチウムイオン二次電池負極。
（６）上記（５）に記載のリチウムイオン二次電池負極を備えるリチウムイオン二次電池。 That is, the present invention provides the following (1) to (6).
(1) A negative electrode mixture adjusting step for preparing a negative electrode mixture comprising a mesocarbon microsphere graphitized product and a graphite particle having an average particle size smaller than this, which is a method for producing a negative electrode for a lithium ion secondary battery A negative electrode forming step of attaching the negative electrode mixture to the electrode plate to form an electrode plate having a layer made of the negative electrode mixture, and a layer made of the negative electrode mixture having a density of 1.8 g / cm 3 above and then, and the production method of the mesocarbon spherules graphitized product of a lithium ion secondary battery negative electrode of the aspect ratio and a pressurizing step of applying pressure to 1.4 or less in this layer.
(2) In the negative electrode mixture, a mass ratio of the mesocarbon microsphere graphitized product to a total mass of the mesocarbon microsphere graphitized product and the graphitic particle is more than 25 mass% and 75 mass% or less. The manufacturing method of the lithium ion secondary battery negative electrode as described in said (1) which is.
(3) The method for producing a negative electrode for a lithium ion secondary battery according to the above (1) or (2), wherein the graphite particles are non-flaky graphite particles.
(4) The average particle diameter of the mesocarbon microsphere graphitized product is 5 to 100 μm, and the average particle diameter of the graphite particles is 1 to 30 μm, according to any one of (1) to (3) above. Manufacturing method of lithium ion secondary battery negative electrode.
(5) A negative electrode mixture containing a mesocarbon microsphere graphitized product having an aspect ratio of 1.4 or less and a graphite particle having an average particle size smaller than the mesocarbon, and has a density of 1.8 g / cm 3 or more. A lithium ion secondary battery negative electrode having a layer on the electrode plate.
(6) A lithium ion secondary battery comprising the lithium ion secondary battery negative electrode according to (5) above.

本発明のリチウムイオン二次電池負極の製造方法によれば、負極体積当りの放電容量が増大しており、かつ、サイクル特性も従来と同等以上に高位であるリチウムイオン二次電池を製造することができる。   According to the method for producing a negative electrode of a lithium ion secondary battery of the present invention, a lithium ion secondary battery having an increased discharge capacity per negative electrode volume and a cycle characteristic higher than that of a conventional one is produced. Can do.

また、本発明のリチウムイオン二次電池負極の製造方法においては、前記負極合剤において、前記メソカーボン小球体黒鉛化品と前記黒鉛質粒子との合計質量に対する、前記メソカーボン小球体黒鉛化品の質量割合が、２５質量％超、７５質量％以下であることが好ましく、これにより、充電時の電極（負極）の膨張を抑制できるため、実質の負極体積当りの放電容量が増大しており、かつ、サイクル特性（容量維持率）は従来よりも高位であるリチウムイオン二次電池を製造することができるという効果を奏する。   In the method for producing a lithium ion secondary battery negative electrode of the present invention, the mesocarbon microsphere graphitized product with respect to a total mass of the mesocarbon microsphere graphitized product and the graphite particles in the negative electrode mixture. The mass ratio is more than 25 mass% and preferably 75 mass% or less, and this can suppress the expansion of the electrode (negative electrode) during charging, so that the actual discharge capacity per negative electrode volume is increased. And there exists an effect that a lithium ion secondary battery whose cycling characteristics (capacity maintenance factor) is higher than before can be manufactured.

さらに、本発明のリチウムイオン二次電池負極の製造方法においては、前記黒鉛質粒子が非燐片状黒鉛質粒子であることが好ましく、これにより、負極体積当りの放電容量がより増大しており、かつ、サイクル特性（容量維持率）は従来よりも高位であるリチウムイオン二次電池を製造することができるという効果を奏する。   Furthermore, in the method for producing a negative electrode for a lithium ion secondary battery of the present invention, the graphite particles are preferably non-flaky graphite particles, whereby the discharge capacity per negative electrode volume is further increased. And there exists an effect that a lithium ion secondary battery whose cycling characteristics (capacity maintenance factor) is higher than before can be manufactured.

また、本発明のリチウムイオン二次電池負極は、負極体積当りの放電容量が従来よりも高く、かつ、サイクル特性は従来と同程度以上に高位である。   Further, the negative electrode of the lithium ion secondary battery of the present invention has a higher discharge capacity per negative electrode volume than the conventional one, and the cycle characteristics are higher than the conventional one.

本発明のリチウムイオン二次電池負極の製造方法は、リチウムイオン二次電池負極の製造方法であって、メソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤を調製する負極合剤調整工程と、前記負極合剤を電極板に付け、前記負極合剤からなる層を有する電極板を形成する負極形成工程と、前記負極合剤からなる層に、この層の密度を１．８ｇ／ｃｍ３以上とし、かつ、この層中の前記メソカーボン小球体黒鉛化品のアスペクト比を１．４以下とする圧力を加える加圧工程とを具備するリチウムイオン二次電池負極の製造方法である。
このようなリチウムイオン二次電池負極の製造方法を、以下では「本発明の製造方法」ともいう。 The method for producing a lithium ion secondary battery negative electrode of the present invention is a method for producing a lithium ion secondary battery negative electrode, comprising mesocarbon microsphere graphitized products and graphitic particles having an average particle size smaller than this. A negative electrode mixture adjusting step for preparing a negative electrode mixture, a negative electrode forming step for forming the electrode plate having the layer made of the negative electrode mixture by attaching the negative electrode mixture to the electrode plate, and a layer made of the negative electrode mixture And a pressurizing step for applying a pressure to set the density of this layer to 1.8 g / cm 3 or more and to set the aspect ratio of the mesocarbon microsphere graphitized product in this layer to 1.4 or less. It is a manufacturing method of an ion secondary battery negative electrode.
Hereinafter, such a method for producing a lithium ion secondary battery negative electrode is also referred to as “the production method of the present invention”.

また、本発明のリチウムイオン二次電池負極は、アスペクト比が１．４以下であるメソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤からなり、密度が１．８ｇ／ｃｍ３以上である層を電極板上に有する、リチウムイオン二次電池負極である。
このようなリチウムイオン二次電池負極を、以下では「本発明の負極」ともいう。
この本発明の負極は、本発明の製造方法により製造され得る。 The lithium ion secondary battery negative electrode of the present invention comprises a negative electrode mixture comprising a mesocarbon microsphere graphitized product having an aspect ratio of 1.4 or less and a graphitic particle having an average particle size smaller than this. A lithium ion secondary battery negative electrode having a layer having a density of 1.8 g / cm 3 or more on the electrode plate.
Hereinafter, such a lithium ion secondary battery negative electrode is also referred to as a “negative electrode of the present invention”.
This negative electrode of the present invention can be produced by the production method of the present invention.

また、本発明のリチウムイオン二次電池は、本発明の負極を備えるリチウムイオン二次電池である。
このようなリチウムイオン二次電池を、以下では「本発明の電池」ともいう。
さらに、本発明の製造方法、本発明の負極、および本発明の電池の全てを指して、単に「本発明」ともいう。 Moreover, the lithium ion secondary battery of this invention is a lithium ion secondary battery provided with the negative electrode of this invention.
Hereinafter, such a lithium ion secondary battery is also referred to as “battery of the present invention”.
Furthermore, the production method of the present invention, the negative electrode of the present invention, and the battery of the present invention are all referred to as “the present invention”.

以下では、まず始めに本発明の製造方法について説明するが、本発明の負極においてメソカーボン小球体黒鉛化品、黒鉛質粒子等は本発明の製造方法と同様なものであり、アスペクト比、平均粒径、電極密度等の定義に関しても同様である。従って、本発明の負極に関するそれらの説明は省略する。   In the following, the production method of the present invention will be described first, but in the negative electrode of the present invention, the mesocarbon microsphere graphitized product, the graphite particles and the like are the same as the production method of the present invention, and the aspect ratio, average The same applies to the definitions of particle size, electrode density, and the like. Therefore, those descriptions regarding the negative electrode of the present invention are omitted.

本発明の製造方法について説明する。
本発明の製造方法は、負極合剤調製工程と、負極形成工程と、加圧工程とを具備する。 The production method of the present invention will be described.
The manufacturing method of this invention comprises a negative mix preparation process, a negative electrode formation process, and a pressurization process.

＜負極合剤調製工程＞
本発明の製造方法が具備する負極合剤調製工程では、メソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤を調製する。 <Negative electrode mixture preparation process>
In the negative electrode mixture preparation step included in the production method of the present invention, a negative electrode mixture containing a mesocarbon microsphere graphitized product and graphite particles having an average particle size smaller than this is prepared.

本発明の製造方法が具備する負極合剤調製工程において、メソカーボン小球体黒鉛化品は、メソカーボン小球体を１５００℃以上、好ましくは２８００〜３３００℃で黒鉛化処理して得ることができるものである。   In the negative electrode mixture preparation step included in the production method of the present invention, the mesocarbon microsphere graphitized product can be obtained by graphitizing the mesocarbon microsphere at 1500 ° C. or higher, preferably 2800-3300 ° C. It is.

ここでメソカーボン小球体とは、タールやピッチ中の芳香族成分が縮合やスタッキングした球状物である。
例えば、石炭系および／または石油系ピッチを熱処理した際にピッチマトリックス中に生成する光学的異方性を示す小球体を濾過して得られる濾過残渣、または有機溶媒を用いてピッチマトリックス中から分離した小球体である。 Here, the mesocarbon spherule is a sphere obtained by condensation or stacking of aromatic components in tar or pitch.
For example, filtration residue obtained by filtering small spheres showing optical anisotropy generated in a pitch matrix when coal-based and / or petroleum-based pitch is heat-treated, or separated from the pitch matrix using an organic solvent It is a small sphere.

ここで、石炭系および／または石油系ピッチとは、例えば、コールタール、タール軽油、タール中油、タール重油、ナフタリン油、アントラセン油、コールタールピッチ、ピッチ油、メソフェーズピッチ、酸素架橋石油ピッチ、ヘビーオイルなどである。   Here, the coal-based and / or petroleum-based pitch is, for example, coal tar, tar light oil, tar medium oil, tar heavy oil, naphthalene oil, anthracene oil, coal tar pitch, pitch oil, mesophase pitch, oxygen-crosslinked petroleum pitch, heavy Such as oil.

この石炭系および／または石油系ピッチの熱処理は、減圧下、常圧下または加圧下のいずれであってもよい。この熱処理の温度範囲は通常３００〜１２００℃、好ましくは３５０〜６００℃であり、熱処理時間は特に限定されないが、０．５〜１００ｈ程度である。
また、この熱処理は、還元性雰囲気（酸素濃度３体積％以下程度）下で行なうのが好ましいが、若干の（弱）酸化性雰囲気下で行なうこともできる。なお、この熱処理は、複数回行ってもよい。
さらに、この熱処理後の処理は、特に限定されず、任意の方法でメソカーボン小球体を分離、粉砕してもよい。例えば、分離は加熱加圧濾過、加熱減圧濾過などにより行うことができる。 The heat treatment of the coal-based and / or petroleum-based pitch may be performed under reduced pressure, normal pressure, or increased pressure. The temperature range of this heat treatment is usually 300 to 1200 ° C., preferably 350 to 600 ° C., and the heat treatment time is not particularly limited, but is about 0.5 to 100 hours.
This heat treatment is preferably performed in a reducing atmosphere (oxygen concentration of about 3% by volume or less), but can also be performed in a slight (weak) oxidizing atmosphere. Note that this heat treatment may be performed a plurality of times.
Furthermore, the treatment after the heat treatment is not particularly limited, and the mesocarbon spherules may be separated and pulverized by any method. For example, the separation can be performed by heating and pressure filtration, heating and vacuum filtration, or the like.

このようなメソカーボン小球体黒鉛化品は、その形状がほぼ球状（球形状、断面が楕円形状のものや、角の取れた不定形であって全体として球形状に近い形状であるもの等）である。また、このメソカーボン小球体黒鉛化品はアスペクト比が１．１以下であることが好ましい。アスペクト比の定義は後述する。
また、その粒径は特に限定されない。平均粒径として好ましい範囲等は後述する。 Such mesocarbon microsphere graphitized products are almost spherical in shape (spherical shape, elliptical in cross section, indeterminate shape with rounded corners, and a shape close to a spherical shape as a whole) It is. The mesocarbon microsphere graphitized product preferably has an aspect ratio of 1.1 or less. The definition of the aspect ratio will be described later.
The particle size is not particularly limited. A preferable range of the average particle diameter will be described later.

本発明の製造方法が具備する負極合剤調製工程において、黒鉛質粒子は、一般に市販されている石油または石炭を原料とした人造黒鉛、あるいは天然黒鉛等の微粉砕品を用いることができる。
具体的には、例えば、前記メソカーボン小球体黒鉛化品の原料として用いることができる石炭系および／または石油系ピッチを、熱処理して重縮合させたメソフェーズ焼成体、メソフェーズ小球体、およびコークス類を、１５００℃以上、好ましくは２８００〜３３００℃で黒鉛化処理したものが挙げられる。
さらに、この黒鉛質粒子は、前記メソカーボン小球体黒鉛化品自体であって、平均粒径を相対的に小さくしたものであってもよい。あるいは、メソカーボン小球体黒鉛化品を粉砕したものでもよい。 In the negative electrode mixture preparation step included in the production method of the present invention, as the graphite particles, commercially available artificial graphite using petroleum or coal as a raw material, or finely pulverized products such as natural graphite can be used.
Specifically, for example, mesophase fired bodies, mesophase small spheres, and cokes obtained by heat-treating and polycondensing coal-based and / or petroleum-based pitches that can be used as raw materials for the mesocarbon microsphere graphitized products. Is graphitized at 1500 ° C or higher, preferably 2800-3300 ° C.
Further, the graphite particles may be the mesocarbon microsphere graphitized product itself, and may have a relatively small average particle diameter. Alternatively, a mesocarbon microsphere graphitized product may be pulverized.

このような黒鉛質粒子の形状は特に限定されないが、非鱗片状であることが好ましい。つまり、前記黒鉛質粒子は非鱗片状黒鉛質粒子であることが好ましい。
ここで非鱗片状とは、鱗片状（外観が葉片状で劈開しやすい性質をもっているもの）でない形状であって、例えば、球状、略球状（断面が楕円形状のものや、角の取れた不定形であって全体として球形状に近い形状であるもの等）、塊状、不定形状等が挙げられる。前記黒鉛質粒子はこのような非鱗片状であって、後に定義を説明するアスペクト比が１．１以下であることが好ましい。 The shape of such graphite particles is not particularly limited, but is preferably non-flaky. That is, the graphite particles are preferably non-flaky graphite particles.
Here, the non-flaky shape is a shape that is not scaly (having a flake-like appearance and easily cleaved), and is, for example, spherical, substantially spherical (having an elliptical cross section, or a rounded corner) Indeterminate shape and a shape close to a spherical shape as a whole), block shapes, indefinite shapes, and the like. It is preferable that the graphite particles have such a non-flaky shape and have an aspect ratio of 1.1 or less, whose definition will be described later.

このように前記黒鉛質粒子が非鱗片状黒鉛質粒子であると高密度化したときに配向しずらく、Ｌｉイオンの出入りに支障をきたさず、サイクル特性も悪化し難いという効果を奏するので好ましい。
このような効果は、本発明のように電極密度が１．８ｇ／ｃｍ３と高い（詳細は後述する）場合により顕著となる。 As described above, it is preferable that the graphite particles are non-flaky graphite particles because they are difficult to be oriented when densified, do not hinder the entry and exit of Li ions, and are difficult to deteriorate the cycle characteristics. .
Such an effect becomes more prominent when the electrode density is as high as 1.8 g / cm 3 (details will be described later) as in the present invention.

本発明の製造方法において、このような黒鉛質粒子は、前記メソカーボン小球体黒鉛化品よりも平均粒径が小さい。
この黒鉛質粒子を製造した段階で、その平均粒径が前記メソカーボン小球体黒鉛化品よりも小さい場合は、そのまま用いることができる。逆に大きい場合や、小さいが望ましい平均粒径に調製する場合等には、この黒鉛質粒子の平均粒径を前記メソカーボン小球体黒鉛化品よりも小さくする。この方法は限定されない。例えば、公知の粉砕方法（ボールミルを用いる方法、クラッシャーを用いる方法等）を適用することができる。また、例えば、篩を用いて粒度が小さい部分のみを用いることもできる。 In the production method of the present invention, such graphitic particles have an average particle size smaller than that of the mesocarbon microsphere graphitized product.
If the average particle size is smaller than that of the mesocarbon microsphere graphitized product at the stage of producing the graphite particles, they can be used as they are. On the contrary, when the particle size is large or when the particle size is adjusted to a desirable average particle size, the average particle size of the graphite particles is made smaller than that of the mesocarbon microsphere graphitized product. This method is not limited. For example, a known pulverization method (a method using a ball mill, a method using a crusher, or the like) can be applied. Further, for example, only a portion having a small particle size can be used by using a sieve.

ここで、平均粒径について説明する。本発明において前記メソカーボン小球体黒鉛化品および黒鉛質粒子の平均粒径とはレーザー回折式粒度分布計により測定し、粒度分布の累積度数が体積百分率で５０％になる値である。
次にアスペクト比の測定方法について説明する。
まず、測定する対象物である前記メソカーボン小球体黒鉛化品または前記黒鉛質粒子をエポキシ樹脂に埋め込む。または後述する方法で電極板上に付けた後、その電極板ごと同様に樹脂に埋め込む。そして、十分に乾燥させた後、表面を研磨し顕微鏡観察用コマとする。そして、この顕微鏡観察用コマの表面を偏光顕微鏡で観察して、メソカーボン小球体黒鉛化品の粒子または黒鉛質粒子の最大長軸長（ａ）、およびそれに直交する軸の長さ（ｂ）を測定する。このａとｂとの相乗平均値を求め観察したメソカーボン小球体黒鉛化品または黒鉛質粒子の１粒子のａ／ｂの値を求める。そして、同様に５０個の粒子について測定して求めたａ／ｂの平均値を、測定する対象物である前記メソカーボン小球体黒鉛化品または前記黒鉛質粒子のアスペクト比とする。 Here, the average particle diameter will be described. In the present invention, the average particle size of the mesocarbon microsphere graphitized product and the graphite particles is a value that is measured by a laser diffraction particle size distribution meter and the cumulative frequency of the particle size distribution is 50% by volume.
Next, a method for measuring the aspect ratio will be described.
First, the mesocarbon microsphere graphitized product or the graphitic particle as an object to be measured is embedded in an epoxy resin. Or after attaching on an electrode plate by the method mentioned later, the whole electrode plate is similarly embedded in resin. And after making it fully dry, the surface is grind | polished and it is set as the top for microscope observation. Then, the surface of the microscope observation piece is observed with a polarizing microscope, and the maximum major axis length (a) of the mesocarbon microsphere graphitized particles or graphitic particles, and the length of the axis orthogonal to the length (b). Measure. The a / b value of one mesocarbon microsphere graphitized product or graphitic particle obtained by calculating the geometric mean value of a and b was determined. Similarly, the average value of a / b obtained by measuring 50 particles is defined as the aspect ratio of the mesocarbon microsphere graphitized product or the graphitic particle as the object to be measured.

なお、顕微鏡観察時にメソカーボン小球体黒鉛化品と、黒鉛質粒子とを区別する方法は次の通りである。
例えば、黒鉛質粒子が、前記メソカーボン小球体黒鉛化品自体であってこれを粉砕等して平均粒径を相対的に小さくしたものである場合、顕微鏡観察下において、この黒鉛質粒子（メソカーボン小球体黒鉛化品の粉砕等したもの）は、メソカーボン小球体黒鉛化品とは形状が明らかに違う。つまり、前記メソカーボン小球体黒鉛化品は上記のようにほぼ球状であるのに対し、黒鉛質粒子はそれが割れた形状（例えば不定形状）である。したがって、この形状の差異によりメソカーボン小球体黒鉛化品と、黒鉛質粒子とを区別することができる。
また、例えば、メソカーボン小球体黒鉛化品と黒鉛質粒子とが共に略球形である場合でも、顕微鏡観察下においてはその光沢度や表面凹凸度が相違する。これはこれらの形成過程の差異によるものと考えられる。具体的にはメソカーボン小球体黒鉛化品よりも黒鉛質粒子のほうが光沢度が高く、表面に微細な凹凸が多い。 In addition, the method of distinguishing mesocarbon microsphere graphitized products and graphite particles at the time of microscopic observation is as follows.
For example, when the graphite particles are the mesocarbon microsphere graphitized product itself, which is pulverized or the like and has a relatively small average particle size, the graphite particles (meso The shape of the carbon small sphere graphitized product) is clearly different from that of the mesocarbon small sphere graphitized product. That is, the mesocarbon microsphere graphitized product is substantially spherical as described above, whereas the graphite particles have a shape (for example, an indefinite shape) in which the graphite particles are cracked. Therefore, the mesocarbon microsphere graphitized product and the graphite particles can be distinguished by the difference in shape.
Further, for example, even when the mesocarbon microsphere graphitized product and the graphite particles are both substantially spherical, the glossiness and surface roughness are different under microscopic observation. This is thought to be due to the difference in these formation processes. Specifically, the graphite particles have higher gloss than the mesocarbon microsphere graphitized product, and there are many fine irregularities on the surface.

本発明の製造方法において、前記メソカーボン小球体黒鉛化品および前記黒鉛質粒子の平均粒径は、前述のように、前記黒鉛質粒子の方が小さい。
これを満たしていれば各々の平均粒径は限定されないものの、前記メソカーボン小球体黒鉛化品の平均粒径が５〜１００μｍであって、前記黒鉛質粒子の平均粒径が１〜３０μｍであることが好ましい。各々の粒径がこのような範囲であれば、メソカーボン小球体黒鉛化品が形成する空隙に黒鉛質粒子が入り込み、メソカーボン小球体黒鉛化品の変形を抑制するという効果を奏するからである。
前記メソカーボン小球体黒鉛化品の平均粒径は、１０〜６０μｍがさらに好ましく、２０〜５０μｍが最も好ましい。
また、前記黒鉛質粒子の平均粒径は、２〜２５μｍがさらに好ましく、３〜２０μｍが最も好ましい。 In the production method of the present invention, the average particle size of the mesocarbon microsphere graphitized product and the graphitic particle is smaller in the graphitic particle as described above.
Each average particle size is not limited as long as this is satisfied, but the average particle size of the mesocarbon microsphere graphitized product is 5 to 100 μm, and the average particle size of the graphitic particles is 1 to 30 μm. It is preferable. This is because, if each particle size is in such a range, the graphite particles enter the voids formed by the mesocarbon microsphere graphitized product, and the deformation of the mesocarbon microsphere graphitized product is suppressed. .
The average particle size of the mesocarbon microsphere graphitized product is more preferably 10 to 60 μm, and most preferably 20 to 50 μm.
The average particle size of the graphite particles is more preferably 2 to 25 μm, and most preferably 3 to 20 μm.

本発明の製造方法が具備する負極合剤調製工程では、前記メソカーボン小球体黒鉛化品と、前記黒鉛質粒子とを含む負極合剤を調製する。
次に、この負極合剤について説明する。 In the negative electrode mixture preparation step included in the production method of the present invention, a negative electrode mixture containing the mesocarbon microsphere graphitized product and the graphite particles is prepared.
Next, this negative electrode mixture will be described.

前記負極合剤は、前記メソカーボン小球体黒鉛化品と、前記黒鉛質粒子とを、結着剤、および必要であれば溶媒と混合して調製するものである。   The negative electrode mixture is prepared by mixing the mesocarbon microsphere graphitized product and the graphite particles with a binder and, if necessary, a solvent.

ここで結着剤としては、電解質に対して化学的安定性、電気化学的安定性を有するものが好ましく、有機溶媒に溶解および／または分散させる有機系結着剤はもちろんのこと、水系溶媒に溶解および／または分散する水系結着剤が広く用いることができる。例えば、ポリフッ化ビニリデン、ポリテトラフルオロエチレン等のフッ素系樹脂、ポリエチレン、ポリビニルアルコールなどの樹脂、さらにはカルボキシメチルセルロース、スチレンブタジエンゴムなどのゴムなどが用いられるが、ポリフッ化ビニリデン等の有機結着剤を用いることが特に好ましい。これらを併用することもできる。結着剤は、通常、前記負極合剤の全質量中０．５〜２０質量％の割合で使用されるのが好ましい。   Here, as the binder, those having chemical stability and electrochemical stability with respect to the electrolyte are preferable, and not only the organic binder dissolved and / or dispersed in the organic solvent, but also the aqueous solvent. A water-based binder that dissolves and / or disperses can be widely used. For example, fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, resins such as polyethylene and polyvinyl alcohol, and rubbers such as carboxymethyl cellulose and styrene butadiene rubber are used. Organic binders such as polyvinylidene fluoride It is particularly preferable to use These can also be used together. In general, the binder is preferably used at a ratio of 0.5 to 20% by mass in the total mass of the negative electrode mixture.

また、ここで溶媒としては、従来のリチウムイオン二次電池用負極合剤の調製に使用される通常の溶媒が使用されるが、溶媒自体が結着剤として使用できるものが好ましく使用される。具体的には、Ｎ―メチルピロリドン、ジメチルホルムアミド、水、アルコールなどが挙げられる。   Moreover, as a solvent here, although the normal solvent used for preparation of the conventional negative mix for lithium ion secondary batteries is used, what can use solvent itself as a binder is used preferably. Specific examples include N-methylpyrrolidone, dimethylformamide, water, alcohol and the like.

また、前記負極合剤に、その他の材料として、従来のリチウムイオン二次電池用負極材料の作製に通常使用される導電材、改質材、添加剤などを共存させてもよい。例えば、天然黒鉛、人造黒鉛、カーボンブラック、気相成長炭素繊維、低結晶性炭素粒子またはこれらの黒鉛化物などを添加してもよい。これらのその他の材料は、一概に言えないが、総量として前記負極合剤の全質量中０．１〜５０質量％の割合で使用されるのが好ましい。   Moreover, you may coexist the said negative electrode mixture with the other electrically conductive material, modifier, additive, etc. which are normally used for preparation of the negative electrode material for lithium ion secondary batteries. For example, natural graphite, artificial graphite, carbon black, vapor grown carbon fiber, low crystalline carbon particles, or a graphitized product thereof may be added. These other materials cannot be generally described, but are preferably used in a proportion of 0.1 to 50% by mass in the total mass of the negative electrode mixture.

このような負極合剤は、前記メソカーボン小球体黒鉛化品、前記黒鉛質粒子、および前記結着剤を、必要であれば前記溶媒、前記その他の材料と共に混合して調製する。
この調製は公知の攪拌機、混合機、混練機、ニーダーなどを用いて行うことができる。 Such a negative electrode mixture is prepared by mixing the mesocarbon microsphere graphitized product, the graphite particles, and the binder together with the solvent and the other materials, if necessary.
This preparation can be performed using a known stirrer, mixer, kneader, kneader or the like.

なお、前記負極合剤において、前記メソカーボン小球体黒鉛化品と、前記黒鉛質粒子との混合比は限定されないが、前記メソカーボン小球体黒鉛化品と前記黒鉛質粒子との合計質量に対する、前記メソカーボン小球体黒鉛化品の質量割合が、２５質量％超、７５質量％以下であることが好ましい。２６〜７０質量％であることがさらに好ましく、３０〜７０質量％であることが最も好ましい。このような範囲であれば、充電時の電極膨張をより抑制するという効果を奏するので好ましい。   In the negative electrode mixture, the mixing ratio of the mesocarbon small sphere graphitized product and the graphite particles is not limited, but with respect to the total mass of the mesocarbon small sphere graphitized product and the graphite particles, The mass ratio of the mesocarbon microsphere graphitized product is preferably more than 25 mass% and 75 mass% or less. It is more preferable that it is 26-70 mass%, and it is most preferable that it is 30-70 mass%. If it is such a range, since there exists an effect of suppressing the electrode expansion at the time of charge, it is preferable.

＜負極形成工程＞
本発明の製造方法が具備する負極形成工程では、上記のように調製した負極合剤を電極板に付け、前記負極合剤からなる層（以下、単に「負極合剤層」ともいう）を有する電極板を形成する。 <Negative electrode forming step>
In the negative electrode forming step included in the production method of the present invention, the negative electrode mixture prepared as described above is attached to an electrode plate and has a layer composed of the negative electrode mixture (hereinafter, also simply referred to as “negative electrode mixture layer”). An electrode plate is formed.

ここで用いる電極板の形状は特に限定されない。箔状、またはメッシュ、エキスパンドメタルなどの網状のものなどが用いることができる。また、この電極板の材質としては、銅、ステンレス、ニッケルなどが挙げられる。この電極板の厚さは特に限定されず、例えば箔状の場合は、５〜２０μｍであることが好ましい。   The shape of the electrode plate used here is not particularly limited. A foil shape or a net shape such as a mesh or expanded metal can be used. Moreover, copper, stainless steel, nickel, etc. are mentioned as a material of this electrode plate. The thickness of the electrode plate is not particularly limited. For example, in the case of a foil shape, the thickness is preferably 5 to 20 μm.

このような電極板に前記負極合剤を付ける。この方法は限定されず、例えば従来公知の負極の作製方法に基づいて付けることができる。前記負極合剤を前記電極板の片面または両面に塗布し、その後、乾燥して、前記負極合剤層を形成する方法が好ましい。前記溶媒を用いた前記負極合剤を用いると、この負極合剤層をより均一かつ強固に前記電極板に付けることができるので好ましい。また、この負極合剤層の層厚は１０〜２００μｍであることが好ましく、２０〜２００μｍであることがさらに好ましい。   The negative electrode mixture is attached to such an electrode plate. This method is not limited, and can be applied based on, for example, a conventionally known method for producing a negative electrode. A method in which the negative electrode mixture is applied to one or both surfaces of the electrode plate and then dried to form the negative electrode mixture layer is preferable. It is preferable to use the negative electrode mixture using the solvent because the negative electrode mixture layer can be more uniformly and firmly attached to the electrode plate. The layer thickness of the negative electrode mixture layer is preferably 10 to 200 μm, and more preferably 20 to 200 μm.

具体的には、例えば、前記メソカーボン小球体黒鉛化品および前記黒鉛質粒子を、ポリテトラフルオロエチレン等のフッ素系樹脂粉末と共に、イソプロピルアルコール等の溶媒中で混合、混練した後、ドクターブレードを用いて前記電極板上に塗布することができる。そして、乾燥機を用いて乾燥させ、前記電極板上に前記負極合剤層を形成する。
また、例えば、前記メソカーボン小球体黒鉛化品および前記黒鉛質粒子を、ポリフッ化ビニリデン等のフッ素系樹脂、カルボキシメチルセルロース、およびスチレンブタジエンラバーからなる群から選択される少なくとも１つ、および、Ｎ−メチルピロリドン、ジメチルホルムアミド、水、またはアルコール等の溶媒と混合してスラリーとした後、ドクターブレードを用いて前記電極板上に塗布することができる。そして、乾燥機を用いて乾燥させ、前記電極板上に前記負極合剤層を形成する。
また、例えば、前記メソカーボン小球体黒鉛化品および前記黒鉛質粒子を、ポリエチレン、ポリビニルアルコールなどの樹脂粉末と乾式混合し、これと前記電極板を金型内でホットプレス成型して前記電極板上に前記負極合剤層を形成することができる。 Specifically, for example, the mesocarbon microsphere graphitized product and the graphite particles are mixed and kneaded in a solvent such as isopropyl alcohol together with a fluorine resin powder such as polytetrafluoroethylene, and then a doctor blade is used. And can be applied onto the electrode plate. And it dries using a dryer, and forms the said negative mix layer on the said electrode plate.
Further, for example, the mesocarbon microsphere graphitized product and the graphite particles may be at least one selected from the group consisting of a fluorine-based resin such as polyvinylidene fluoride, carboxymethyl cellulose, and styrene butadiene rubber, and N- After mixing with a solvent such as methylpyrrolidone, dimethylformamide, water, or alcohol to form a slurry, it can be applied onto the electrode plate using a doctor blade. And it dries using a dryer, and forms the said negative mix layer on the said electrode plate.
Further, for example, the mesocarbon microsphere graphitized product and the graphitic particles are dry-mixed with a resin powder such as polyethylene and polyvinyl alcohol, and this and the electrode plate are hot-press molded in a mold to form the electrode plate The negative electrode mixture layer can be formed thereon.

本発明の製造方法が具備する加圧工程では、前記負極合剤からなる層に、この層の密度（以下、「電極密度」ともいう）を１．８ｇ／ｃｍ３以上とし、かつ、この層中の前記メソカーボン小球体黒鉛化品のアスペクト比を１．４以下とする圧力を加える。
この圧力を加える方法、つまり加圧方法は限定されず、この負極合剤層の電極密度、およびアスペクト比を所定の範囲に調整することができる方法であればよい。
例えば、上記のように負極合剤層を形成した後、ローラープレス等のプレス加工をする方法が挙げられる。プレス加工等の圧着を行うと、前記負極合剤層と前記電極板との接着強度をさらに高めることができる点からも好ましい。 In the pressurization step included in the production method of the present invention, the density of this layer (hereinafter also referred to as “electrode density”) is 1.8 g / cm 3 or more in the layer composed of the negative electrode mixture, and this layer A pressure is applied so that the aspect ratio of the mesocarbon microsphere graphitized product is 1.4 or less.
The method of applying this pressure, that is, the pressurizing method is not limited, and any method can be used as long as the electrode density and aspect ratio of the negative electrode mixture layer can be adjusted within a predetermined range.
For example, after forming a negative mix layer as mentioned above, the method of performing press work, such as a roller press, is mentioned. When pressure bonding such as press working is performed, it is also preferable from the viewpoint that the adhesive strength between the negative electrode mixture layer and the electrode plate can be further increased.

なお、電極密度とアスペクト比の調整は、圧力のみならず、負極合剤の構成材料組成（活物質や結着剤の配合割合など）にも依存する。   The adjustment of the electrode density and the aspect ratio depends not only on the pressure but also on the constituent material composition of the negative electrode mixture (such as the mixing ratio of the active material and the binder).

ここで電極密度が１．８ｇ／ｃｍ３以上となるように加圧すると、前記負極合剤層の単位体積当りの放電容量が向上するで好ましい。
ただし、電極密度を高くしすぎると、サイクル特性が悪化する場合がある。したがってこの電極密度には上限値がある。この上限値は加圧した結果、前記負極合剤層中の前記メソカーボン小球体黒鉛化品のアスペクト比が１．４超とならない電極密度の値である。
メソカーボン小球体黒鉛化品のアスペクト比が１．４超の場合、前記負極合剤層の膨張が大きくなる傾向がある。 Here, pressurization so that the electrode density is 1.8 g / cm 3 or more is preferable because the discharge capacity per unit volume of the negative electrode mixture layer is improved.
However, if the electrode density is too high, the cycle characteristics may deteriorate. Therefore, this electrode density has an upper limit. This upper limit value is an electrode density value at which the aspect ratio of the mesocarbon microsphere graphitized product in the negative electrode mixture layer does not exceed 1.4 as a result of pressurization.
When the aspect ratio of the mesocarbon microsphere graphitized product is more than 1.4, the negative electrode mixture layer tends to expand.

また、電極密度は、次のような方法で測定した値である。
まず、前記負極合剤層を形成する前の前記電極板の質量を精密天秤で測定し、厚さをマイクロメーターで測定する。次に、この電極板に前記負極合剤層を形成した後、同様に質量および厚さを、精密天秤およびマイクロメーターを用いて測定する。そして、この差から前記負極合剤層のみの質量および厚さを求める。さらに、ここで求めた前記負極合剤層の質量および厚さと、この負極合剤層の表面積から、電極密度を算出する。 The electrode density is a value measured by the following method.
First, the mass of the electrode plate before forming the negative electrode mixture layer is measured with a precision balance, and the thickness is measured with a micrometer. Next, after forming the negative electrode mixture layer on the electrode plate, the mass and thickness are similarly measured using a precision balance and a micrometer. And the mass and thickness of only the negative electrode mixture layer are determined from this difference. Further, the electrode density is calculated from the mass and thickness of the negative electrode mixture layer obtained here and the surface area of the negative electrode mixture layer.

このように本発明ではリチウムイオン二次電池負極の電極密度が１．８ｇ／ｃｍ３以上である。これに対して従来公知のものは１．６ｇ／ｃｍ３程度である。
また、本発明では、前述のように、前記メソカーボン小球体黒鉛化品と前記黒鉛質粒子との合計質量に対する、前記メソカーボン小球体黒鉛化品の質量割合が、２５質量％超、７５質量％以下であることが好ましい。
これに対して従来公知の方法、例えば、特許文献１に記載の方法では、これに相当する比率は２０重量％以下が良いと記載されており、２０重量％を超えた場合は球状粒子からなる黒鉛材料の充填密度が減少して電池としての容量が低下すると記載されている。 Thus, in this invention, the electrode density of a lithium ion secondary battery negative electrode is 1.8 g / cm < 3 > or more. On the other hand, the conventionally known one is about 1.6 g / cm 3 .
In the present invention, as described above, the mass ratio of the mesocarbon microsphere graphitized product to the total mass of the mesocarbon microsphere graphitized product and the graphitic particles is more than 25% by mass and 75% by mass. % Or less is preferable.
On the other hand, in a conventionally known method, for example, the method described in Patent Document 1, it is described that the ratio corresponding to this is preferably 20% by weight or less, and when it exceeds 20% by weight, it is composed of spherical particles. It is described that the packing density of the graphite material decreases and the capacity as a battery decreases.

これより、本発明は従来公知の方法と比較して、次のような点で異なると考えられる。
本発明の製造方法により製造したリチウムイオン二次電池負極（例えば、本発明の負極）のように、電極密度が従来公知のものと比較して高く１．８ｇ／ｃｍ３以上である場合は、上記のように２５質量％超であったほうが負極は崩壊し難くなりサイクル特性は悪化し難い。これに対して従来公知の製造方法で製造したリチウムイオン二次電池のように、電極密度が１．６ｇ／ｃｍ３程度である場合に本発明と同様に２５質量％超とすると、電極の充填密度が低くなるので、２０質量％以下とした方が好ましいと考えられる。 Accordingly, the present invention is considered to be different from the conventionally known method in the following points.
When the electrode density is 1.8 g / cm 3 or higher, as compared with a conventionally known lithium ion secondary battery negative electrode (for example, the negative electrode of the present invention) manufactured by the manufacturing method of the present invention, As described above, when the content exceeds 25% by mass, the negative electrode is less likely to collapse and the cycle characteristics are less likely to deteriorate. On the other hand, when the electrode density is about 1.6 g / cm 3 as in the case of a lithium ion secondary battery manufactured by a conventionally known manufacturing method, if it is more than 25% by mass as in the present invention, the filling of the electrode Since the density is lowered, it is considered preferable to be 20% by mass or less.

このような本発明の製造方法によって、本発明の負極は製造され得る。
本発明の負極は、アスペクト比が１．４以下であるメソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤からなり、電極密度が１．８ｇ／ｃｍ３以上である層を電極板上に有する、リチウムイオン二次電池負極である。 The negative electrode of the present invention can be manufactured by such a manufacturing method of the present invention.
The negative electrode of the present invention comprises a negative electrode mixture containing a mesocarbon microsphere graphitized product having an aspect ratio of 1.4 or less and a graphitic particle having an average particle size smaller than this, and the electrode density is 1.8 g. It is a lithium ion secondary battery negative electrode which has a layer which is more than / cm < 3 > on an electrode plate.

このような本発明の負極において、前記リチウムイオン二次電池用負極合剤において、前記メソカーボン小球体黒鉛化品と前記黒鉛質粒子との合計質量に対する、前記メソカーボン小球体黒鉛化品の質量割合が、２５質量％超、７５質量％以下であることが好ましい。   In such a negative electrode of the present invention, in the negative electrode mixture for a lithium ion secondary battery, the mass of the mesocarbon microsphere graphitized product with respect to the total mass of the mesocarbon microsphere graphitized product and the graphite particles The proportion is preferably more than 25 mass% and 75 mass% or less.

また、本発明の負極において、前記黒鉛質粒子が非燐片状黒鉛質粒子であることが好ましい。   In the negative electrode of the present invention, it is preferable that the graphite particles are non-flaky graphite particles.

さらに、本発明の負極において、前記メソカーボン小球体黒鉛化品の平均粒径が５〜１００μｍであり、前記黒鉛質粒子の平均粒径が１〜３０μｍであることが好ましい。   Furthermore, in the negative electrode of the present invention, it is preferable that the mesocarbon microsphere graphitized product has an average particle size of 5 to 100 μm and the graphite particles have an average particle size of 1 to 30 μm.

次に本発明の電池について説明する。
本発明の電池は、本発明の負極を備えるリチウムイオン二次電池である。
本発明の電池の構成要素は、上記の本発明の負極を用いる以外は特に限定されない。正極、電解質、セパレータなどの他の電池構成要素については一般的なリチウムイオン二次電池の構成要素に準じる。
一般的なリチウムイオン二次電池は、通常、負極、正極および非水電解質を主たる電池構成要素として、正極および負極はそれぞれリチウムイオンの担持体であり、充電時にはリチウムイオンが負極に吸蔵され、放電時に負極から離脱する電池機構に拠っている。
以下に、これら正極、電解質、セパレータなどの、本発明の負極以外のリチウムイオン電池構成要素について説明する。 Next, the battery of the present invention will be described.
The battery of the present invention is a lithium ion secondary battery including the negative electrode of the present invention.
The constituent elements of the battery of the present invention are not particularly limited except that the negative electrode of the present invention is used. Other battery components such as a positive electrode, an electrolyte, and a separator conform to the components of a general lithium ion secondary battery.
A typical lithium ion secondary battery usually has a negative electrode, a positive electrode, and a non-aqueous electrolyte as main battery components. Each of the positive electrode and the negative electrode is a lithium ion carrier, and during charging, lithium ions are occluded in the negative electrode and discharged. It relies on a battery mechanism that sometimes detaches from the negative electrode.
Hereinafter, constituent elements of the lithium ion battery other than the negative electrode of the present invention, such as the positive electrode, the electrolyte, and the separator, will be described.

＜正極＞
正極は、例えば正極材料と結着剤と導電剤よりなる正極合剤を集電体の表面に塗布することにより形成される。正極材料（正極活物質）は、十分量のリチウムを吸蔵（ドープ）／離脱（脱ドープ）し得るものを選択することが好ましい。正極活物質としては、リチウム含有遷移金属酸化物、遷移金属カルコゲン化物、バナジウム酸化物（Ｖ２Ｏ５、Ｖ６Ｏ１３、Ｖ２Ｏ４、Ｖ３Ｏ８など）およびそのリチウム化合物などのリチウム含有化合物、一般式ＭＸＭｏ６Ｓ８−ｙ（式中Ｍは少なくとも一種の遷移金属元素であり、Ｘは０≦Ｘ≦４、Ｙは０≦Ｙ≦１の範囲の数である）で表されるシェブレル相化合物、活性炭、活性炭素繊維などを用いることができる。
前記リチウム含有遷移金属酸化物はリチウムと遷移金属との複合酸化物であり、リチウムと２種類以上の遷移金属を固溶したものであってもよい。 <Positive electrode>
The positive electrode is formed, for example, by applying a positive electrode mixture composed of a positive electrode material, a binder, and a conductive agent to the surface of the current collector. It is preferable to select a positive electrode material (positive electrode active material) that can occlude (dope) / release (de-dope) a sufficient amount of lithium. Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal chalcogenides, vanadium oxides (V 2 O 5 , V 6 O 13 , V 2 O 4 , V 3 O 8, etc.) and lithium compounds such as lithium compounds thereof. Containing compound, general formula M X Mo 6 S 8-y (wherein M is at least one transition metal element, X is a number in the range of 0 ≦ X ≦ 4, Y is 0 ≦ Y ≦ 1) The chevrel phase compound, activated carbon, activated carbon fiber, etc. which are represented can be used.
The lithium-containing transition metal oxide is a composite oxide of lithium and a transition metal, and may be a solid solution of lithium and two or more transition metals.

前記リチウム含有遷移金属酸化物は、具体的には、ＬｉＭ１ １−ｐＭ２ ｐＯ２（式中Ｍ１およびＭ２は少なくとも一種の遷移金属元素であり、ｐは０≦ｐ≦１の範囲の数である）、またはＬｉＭ１ １−ｑＭ２ ｑＯ４（式中Ｍ１およびＭ２は少なくとも一種の遷移金属元素であり、ｑは０≦ｑ≦１の範囲の数である）で示される。
Ｍ、Ｍ１およびＭ２で示される遷移金属は、Ｃｏ、Ｎｉ、Ｍｎ、Ｃｒ、Ｔｉ、Ｖ、Ｆｅ、Ｚｎ、Ａｌ、Ｉｎ、Ｓｎなどであり、好ましいのはＣｏ、Ｆｅ、Ｍｎ、Ｃｒ、Ｔｉ、Ｖ、Ａｌなどである。
好ましい具体例はＬｉＣｏＯ２、ＬｉＸＮｉＹＭ１−ＹＯ２（ＭはＮｉを除く遷移金属元素、好ましくはＣｏ、Ｆｅ、Ｍｎ、Ｃｒ、Ｔｉ、Ｖ、およびＡｌからなる群から選択される少なくとも１つ、０．０５≦Ｘ≦１．１０、０．５≦Ｙ≦１．０）で示されるリチウム複合酸化物、ＬｉＮｉＯ２、ＬｉＭｎＯ２、ＬｉＮｉ０．９Ｃｏ０．１Ｏ２、ＬｉＮｉ０．５Ｍｎ０．５Ｏ２などである。 Specifically, the lithium-containing transition metal oxide is LiM 1 1-p M 2 p O 2 (wherein M 1 and M 2 are at least one transition metal element, and p is 0 ≦ p ≦ 1) LiM 1 1-q M 2 q O 4 (wherein M 1 and M 2 are at least one transition metal element, and q is a number in the range of 0 ≦ q ≦ 1). Indicated by
Transition metals represented by M, M 1 and M 2 are Co, Ni, Mn, Cr, Ti, V, Fe, Zn, Al, In, Sn, etc., preferably Co, Fe, Mn, Cr, Ti, V, Al and the like.
Transition metal elements preferred examples except LiCoO 2, Li X Ni Y M 1-Y O 2 (M is Ni, preferably chosen Co, Fe, Mn, Cr, Ti, V, and from the group consisting of Al Lithium composite oxide represented by at least one, 0.05 ≦ X ≦ 1.10, 0.5 ≦ Y ≦ 1.0), LiNiO 2 , LiMnO 2 , LiNi 0.9 Co 0.1 O 2 , LiNi 0.5 Mn 0.5 O 2 or the like.

前記リチウム含有遷移金属酸化物は、例えば、リチウムと、遷移金属の酸化物または塩類を出発原料として、これら出発原料を所望の金属酸化物の組成に応じて混合し、酸素雰囲気下、６００〜１０００℃の温度で焼成することにより得ることができる。出発原料は酸化物または塩類に限定されず、水酸化物などでもよい。   The lithium-containing transition metal oxide includes, for example, lithium and an oxide or salt of a transition metal as starting materials, and these starting materials are mixed according to the composition of the desired metal oxide, and are 600 to 1000 in an oxygen atmosphere. It can be obtained by firing at a temperature of ° C. The starting material is not limited to oxides or salts, but may be hydroxides.

本発明の電池では、正極活物質は、前記化合物を単独で使用しても、２種類以上併用してもよい。例えば、正極材料に炭酸リチウムなどの炭酸アルカリ塩を添加することもできる。
このような正極材料によって正極を形成するには、例えば、正極材料と結着剤および電極に導電性を付与するための導電剤よりなる正極合剤を集電材の両面に塗布することで正極合剤層を形成する。結着剤としては、本発明の負極において例示したものがいずれも使用可能である。導電剤としては、例えば、炭素材料、黒鉛やカーボンブラックが用いられる。 In the battery of the present invention, the positive electrode active material may be used alone or in combination of two or more. For example, an alkali carbonate such as lithium carbonate can be added to the positive electrode material.
In order to form a positive electrode using such a positive electrode material, for example, a positive electrode mixture comprising a positive electrode material, a binder, and a conductive agent for imparting conductivity to the electrode is applied to both surfaces of the current collector. An agent layer is formed. As the binder, any of those exemplified in the negative electrode of the present invention can be used. As the conductive agent, for example, a carbon material, graphite, or carbon black is used.

正極に用いる集電材の形状は特に限定されないが、箔状、またはメッシュ、エキスパンドメタルなどの網状のものなどが用いられる。集電材の材質としては、アルミニウム、銅、ステンレス、ニッケルなどが挙げられる。集電材の厚さは、箔状の場合は、１０〜４０μｍであることが好ましい。
正極の場合も負極の場合と同様に、正極合剤を溶剤中に分散させることでペースト状にし、このペースト状負極合剤を集電材に塗布し乾燥することによって正極合剤層を形成してよく、正極合剤層を形成した後、さらにプレス加圧などの圧着を行っても構わない。これにより、正極合剤層が均一かつ強固に集電材に接着される。 The shape of the current collector used for the positive electrode is not particularly limited, but a foil or a net-like material such as a mesh or expanded metal is used. Examples of the material for the current collector include aluminum, copper, stainless steel, and nickel. In the case of a foil, the thickness of the current collector is preferably 10 to 40 μm.
In the case of the positive electrode, as in the case of the negative electrode, the positive electrode mixture is dispersed in a solvent to form a paste, and the paste-like negative electrode mixture is applied to a current collector and dried to form a positive electrode mixture layer. In addition, after forming the positive electrode mixture layer, pressure bonding such as press pressing may be further performed. Thereby, the positive electrode mixture layer is uniformly and firmly bonded to the current collector.

＜非水電解質＞
本発明の電池は、非水電解質として液系の電解質のほかに、固体電解質またはゲル電解質などの高分子電解質を使用することができる。
本発明の電池に使用される非水電解質は、通常の非水電解液に使用される電解質塩であり、具体的には、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＣｌＯ４、ＬｉＢ（Ｃ６Ｈ５）、ＬｉＣｌ、ＬｉＢｒ、ＬｉＣＦ３ＳＯ３、ＬｉＣＨ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＮ（ＣＦ３ＣＨ２ＯＳＯ２）２、ＬｉＮ（ＣＦ３ＣＦ３ＯＳＯ２）２、ＬｉＮ（ＨＣＦ２ＣＦ２ＣＨ２ＯＳＯ２）２、ＬｉＮ［（ＣＦ３）２ＣＨＯＳＯ２］２］、ＬｉＢ［（Ｃ６Ｈ３）（ＣＦ３）２］４、ＬｉＡｌＣｌ４、ＬｉＳｉＦ６などのリチウム塩が挙げられる。特にＬｉＰＦ６とＬｉＢＦ４が酸化安定性の点から好ましい。 <Nonaqueous electrolyte>
The battery of the present invention can use a polymer electrolyte such as a solid electrolyte or a gel electrolyte in addition to a liquid electrolyte as a non-aqueous electrolyte.
Non-aqueous electrolyte used in the battery of the present invention is an electrolyte salt used in the conventional non-aqueous electrolyte, specifically, LiPF 6, LiBF 4, LiAsF 6, LiClO 4, LiB (C 6 H 5 ), LiCl, LiBr, LiCF 3 SO 3 , LiCH 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiN (CF 3 CH 2 OSO 2 ) 2 , LiN (CF 3 CF 3 OSO 2 ) 2 , LiN (HCF 2 CF 2 CH 2 OSO 2 ) 2 , LiN [(CF 3 ) 2 CHOSO 2 ] 2 ], LiB [(C 6 H 3 ) (CF 3 ) 2 ] 4 , LiAlCl 4, and a lithium salt such as LiSiF 6. In particular, LiPF 6 and LiBF 4 are preferable from the viewpoint of oxidation stability.

非水電解質液とするための溶媒としては、通常の非水電解液の溶媒として使用されるもが挙げられる。具体的には、エチレンカーボネート、プロピレンカーボネート、ジメチルカーボネート、ジエチルカーボネートなどのカーボネート、１，１−または１，２−ジメトキシエタン、１，２−ジエトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン、γーブトロラクトン、１，３−ジオキソフラン、４−メチルー１，３−ジオキソラン、アニソール、ジエチルエーテルなどのエーテル、スルホラン、メチルスルホランなどのチオエーテル、アセトニトリル、クロロニトリル、プロピオニトリルなどのニトリル、ホウ酸トリメチル、ケイ酸テトラメチル、ニトロメタン、ジメチルホルムアミド、Ｎ−メチルピロリドン、酢酸エチル、トリメチルオルトホルメート、ニトロベンゼン、塩化ベンゾイル、臭化ベンゾイル、テトラヒドロチオフェン、ジメチルスルホキシド、３ーメチルー２−オキサゾリドン、エチレングリコール、サルファイト、ジメチルサルファイトなどの非プロトン性有機溶媒を用いることができる。電解液中の電解質塩の濃度は０．１〜５mol/dm3（０．１〜５mol/l）であることが好ましく、０．５〜３．０mol/dm3（０．５〜３．０mol/l）であることがより好ましい。 Examples of the solvent for making the non-aqueous electrolyte include those used as solvents for ordinary non-aqueous electrolytes. Specifically, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, 1,1- or 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butrolactone, 1,3-dioxofuran, 4-methyl-1,3-dioxolane, ethers such as anisole and diethyl ether, thioethers such as sulfolane and methylsulfolane, nitriles such as acetonitrile, chloronitrile and propionitrile, trimethyl borate, tetrasilicate Methyl, nitromethane, dimethylformamide, N-methylpyrrolidone, ethyl acetate, trimethylorthoformate, nitrobenzene, benzoyl chloride, benzoyl bromide, tetrahydro Thiophene, dimethyl sulfoxide, 3-methyl-2-oxazolidone, ethylene glycol, may be used an aprotic organic solvent such as sulfite, dimethyl sulfite. Preferably the concentration of the electrolyte salt in the electrolytic solution is 0.1~5mol / dm 3 (0.1~5mol / l ), 0.5~3.0mol / dm 3 (0.5~3.0mol / l) is more preferable.

高分子電解質の製造方法は特に制限されないが、例えば、マトリックスを構成する高分子化合物、リチウム塩および非水溶媒（可塑剤）を混合し、加熱して高分子化合物を溶融・溶解する方法、混合用有機溶媒に、高分子化合物、リチウム化合物および非水溶媒を溶解させた後、混合用有機溶媒を蒸発させる方法、重合性モノマー、リチウム塩および非水溶媒を混合し、混合物に紫外線、電子線または分子線などを照射して重合させる方法などを挙げることができる。高分子電解質中の非水溶媒の割合は１０〜９０質量％が好ましく、３０〜８０質量％がより好ましい。１０質量％以上であると導電率が高くなり、９０質量％以下であると機械的強度が強くなり、フィルム化しやすくなる。   The method for producing the polymer electrolyte is not particularly limited. For example, the polymer compound, lithium salt and non-aqueous solvent (plasticizer) constituting the matrix are mixed and heated to melt and dissolve the polymer compound. A method in which a polymer compound, a lithium compound, and a non-aqueous solvent are dissolved in an organic solvent for use, and then the organic solvent for mixing is evaporated. A polymerizable monomer, a lithium salt, and a non-aqueous solvent are mixed. Or the method of irradiating with a molecular beam etc. and polymerizing can be mentioned. The ratio of the nonaqueous solvent in the polymer electrolyte is preferably 10 to 90% by mass, and more preferably 30 to 80% by mass. When it is 10% by mass or more, the electrical conductivity is increased, and when it is 90% by mass or less, the mechanical strength is increased and the film is easily formed.

前記高分子電解質としては、ポリエチレンオキサイドやその架橋体などのエーテル系重合体、ポリメタクリレート系重合体、ポリアクリレート系重合体、ポリビニリデンフルオライドやビニリデンフルオライド−ヘキサフルオロプロピレン共重合体などのフッ素系樹脂などを単独または混合して用いることができる。これらの中では、酸化還元安定性などの観点から、ポリビニリデンフルオライドやビニリデンフルオライド−ヘキサフルオロプロピレン共重合体などのフッ素系樹脂などを用いることが好ましい。高分子ゲル電解質の場合、可塑剤である電解液中の電解質塩濃度は０．１〜５mol/dm3（０．１〜５mol/l）であることが好ましく、０．５〜２．０mol/dm3（０．５〜２．０mol/l）であることがより好ましい。 Examples of the polymer electrolyte include fluorine-based polymers such as polyethylene oxide and its crosslinked polymers, polymethacrylate polymers, polyacrylate polymers, polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers. These resins can be used alone or in combination. In these, it is preferable to use fluorine-type resins, such as a polyvinylidene fluoride and a vinylidene fluoride-hexafluoropropylene copolymer, from viewpoints, such as oxidation-reduction stability. In the case of the polymer gel electrolyte, the concentration of the electrolyte salt in the electrolytic solution as a plasticizer is preferably 0.1 to 5 mol / dm 3 (0.1 to 5 mol / l), and preferably 0.5 to 2.0 mol / l. dm and more preferably 3 (0.5~2.0mol / l).

本発明の電池は、ゲル電解質を用いることができる。
ゲル電解質を用いたリチウムイオン二次電池は、本発明の負極と、正極およびゲル電解質から構成される。例えば、本発明の負極、ゲル電解質、正極の順で積層し、電池の外装材内に収容することで構成される。なお、これに加えて、さらに本発明の負極と正極の外側にゲル電解質を配するようにしてもよい。本発明の負極を用いるゲル電解質のリチウムイオン二次電池（本発明の電池）では、ゲル電解質にプロピレンカーボネートを含有させることができる。また、本発明の負極で用いる前記メソカーボン小球体黒鉛化品および前記黒鉛質粒子として、インピーダンスを十分に低くできる程度にまで微細化（細粒化）したものを用いた場合であっても、不可逆容量を抑制（小さく）することができる。したがって、より大きな放電容量、およびより高い初期充放電効率を得ることができる。 The battery of the present invention can use a gel electrolyte.
A lithium ion secondary battery using a gel electrolyte includes the negative electrode of the present invention, a positive electrode, and a gel electrolyte. For example, the negative electrode, the gel electrolyte, and the positive electrode of the present invention are laminated in this order and accommodated in the battery outer packaging material. In addition to this, a gel electrolyte may be further arranged outside the negative electrode and the positive electrode of the present invention. In the gel electrolyte lithium ion secondary battery using the negative electrode of the present invention (the battery of the present invention), the gel electrolyte can contain propylene carbonate. Further, as the mesocarbon microsphere graphitized product and the graphite particles used in the negative electrode of the present invention, even when using a material that has been refined (fine-grained) to such an extent that impedance can be sufficiently lowered, Irreversible capacity can be suppressed (smaller). Therefore, a larger discharge capacity and higher initial charge / discharge efficiency can be obtained.

＜セパレータ＞
本発明の電池においては、セパレータを使用することもできる。セパレータは特に限定されるものではないが、例えば、織布、不織布、合成樹脂製微多孔膜などが挙げられる。合成樹脂製微多孔膜が好ましいが、なかでもポリオレフィン系製微多孔膜が厚さ、膜強度、膜抵抗などの点から好ましい。具体的には、ポリエチレンおよびポリプロピレン製微多孔膜、またはこれらを複合した微多孔膜などである。 <Separator>
A separator can also be used in the battery of the present invention. Although a separator is not specifically limited, For example, a woven fabric, a nonwoven fabric, a synthetic resin microporous film, etc. are mentioned. A microporous membrane made of synthetic resin is preferred, and among these, a microporous membrane made of polyolefin is preferred from the viewpoint of thickness, membrane strength, membrane resistance, and the like. Specifically, it is a microporous film made of polyethylene and polypropylene, or a microporous film in which these are combined.

本発明の電池の構造は任意であり、その形状、形態について特に限定されるものではなく、用途、搭載機器、要求される充放電容量などに応じて、円筒型、角型、コイン型、ボタン型などの中から任意に選択することができる。より安全性の高い密閉型非水電解液電池を得るためには、過充電などの異常時に電池内圧上昇を感知して電流を遮断させる手段を備えたものであることが好ましい。高分子固体電解質や高分子ゲル電解質電池の場合には、アルミラミネートフィルムに封入した構造とすることもできる。   The structure of the battery of the present invention is arbitrary, and the shape and form thereof are not particularly limited. Depending on the application, mounted equipment, required charge / discharge capacity, etc., a cylindrical shape, a square shape, a coin shape, a button Any type can be selected from among the types. In order to obtain a sealed nonaqueous electrolyte battery with higher safety, it is preferable to include a means for detecting an increase in the internal pressure of the battery and shutting off the current when there is an abnormality such as overcharging. In the case of a polymer solid electrolyte or a polymer gel electrolyte battery, it can also have a structure enclosed in an aluminum laminate film.

次に本発明を実施例により具体的に説明するが、本発明はこれら実施例に限定されるものではない。また、以下の実施例および比較例では、図１に示すような構成の評価用ボタン型二次電池を作製して評価したが、この電池は、本発明の概念に基づき、公知の方法に準じて作製することができる。   EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. Further, in the following Examples and Comparative Examples, evaluation button-type secondary batteries having a configuration as shown in FIG. 1 were produced and evaluated. This battery is based on the concept of the present invention and is in accordance with a known method. Can be produced.

＜実施例１＞
平均粒径２６μｍのメソカーボン小球体黒鉛化品（コールタールから分離したメソカーボン小球体を３０００℃で黒鉛化処理したもの）と、平均粒径１１μｍのメソカーボン小球体黒鉛化品の粉砕品（前記平均粒径２６μｍのメソカーボン小球体黒鉛化品を粉砕したもの）とを、質量比で４０：６０で混合した。ここで得られる混合物を負極材料とする。
次にこの負極材料と、結着剤であるポリフッ化ビニリデンと、溶媒であるＮ−メチルピロリドンとを、ホモミキサーを用いて攪拌（５００ｒｐｍ、５分間）して混合した。ここで負極材料と結着剤とは質量比で９４：６とした。この混合を行うことで負極材料と結着剤と溶媒とからなる負極合剤を調製した。 <Example 1>
A mesocarbon microsphere graphitized product having an average particle size of 26 μm (mesocarbon microspheres separated from coal tar graphitized at 3000 ° C.) and a pulverized product of mesocarbon microsphere graphitized product having an average particle size of 11 μm ( The mesocarbon microsphere graphitized product having an average particle size of 26 μm was mixed at a mass ratio of 40:60. Let the mixture obtained here be a negative electrode material.
Next, this negative electrode material, polyvinylidene fluoride as a binder, and N-methylpyrrolidone as a solvent were mixed by stirring (500 rpm, 5 minutes) using a homomixer. Here, the negative electrode material and the binder were in a mass ratio of 94: 6. By performing this mixing, a negative electrode mixture composed of a negative electrode material, a binder, and a solvent was prepared.

次に、この負極合剤を銅箔（電極板７）上に均一な厚さで塗布し、さらに真空中において９０℃で溶媒を揮発させて乾燥して負極合剤層を形成した。
次に、この銅箔上の負極合剤層をローラープレスによって加圧した。そして、さらに直径１５．５ｍｍの円形状に打ち抜くことで、電極板７上に密着した負極合剤層２を有する負極を作製した。そして、この負極合剤層の電極密度を測定した。測定方法は前述の通りである。
このような測定の結果、この負極合剤層の電極密度は１．８３ｇ／ｃｍ３であった。 Next, this negative electrode mixture was applied to a copper foil (electrode plate 7) with a uniform thickness, and the solvent was evaporated at 90 ° C. in a vacuum to dry the film, thereby forming a negative electrode mixture layer.
Next, the negative electrode mixture layer on the copper foil was pressed by a roller press. And the negative electrode which has the negative mix layer 2 closely_contact | adhered on the electrode plate 7 was produced by further punching in circular shape with a diameter of 15.5 mm. And the electrode density of this negative mix layer was measured. The measuring method is as described above.
As a result of such measurement, the electrode density of the negative electrode mixture layer was 1.83 g / cm 3 .

次にこの負極を樹脂に埋め込み研磨し、偏光顕微鏡による断面観察を行った。断面観察により、メソカーボン小球体黒鉛化品の最大長軸長ａとそれに直交する軸の長さｂとを５０点ずつ測定し、アスペクト比（ａ／ｂ）の平均値を求めた。その結果、実施例１における負極合剤層中のメソカーボン小球体黒鉛化品のアスペクト比は１．３２であった。   Next, this negative electrode was embedded in a resin and polished, and a cross-section was observed with a polarizing microscope. By cross-sectional observation, the maximum major axis length a and the length b of the axis perpendicular to the mesocarbon microsphere graphitized product were measured 50 points at a time, and the average value of the aspect ratio (a / b) was determined. As a result, the aspect ratio of the mesocarbon microsphere graphitized product in the negative electrode mixture layer in Example 1 was 1.32.

次に対極を作製した。この対極は、ニッケルネットからなる集電体（集電体８）が密着したリチウム金属箔４からなる対極である。これは、リチウム金属箔をニッケルネットに押し付け、直径１５．５ｍｍの円形状に打ち抜くことで作製した。   Next, a counter electrode was produced. This counter electrode is a counter electrode made of a lithium metal foil 4 to which a current collector (current collector 8) made of nickel net is adhered. This was prepared by pressing a lithium metal foil against a nickel net and punching it into a circular shape with a diameter of 15.5 mm.

次に、エチレンカーボネートとメチルエチルカーボネートとを質量比で３３：６７で混合してなる溶媒に、ＬｉＰＦ６を１ｍｏｌ／Ｌとなるように溶解させ非水電解液を調製した。そして、得られた非水電解液をポリプロピレン多孔質体に含浸させ、電解質液が含浸されたセパレータ（セパレータ５）を作製した。 Next, LiPF 6 was dissolved in a solvent obtained by mixing ethylene carbonate and methyl ethyl carbonate at a mass ratio of 33:67 so as to be 1 mol / L to prepare a nonaqueous electrolytic solution. Then, the obtained nonaqueous electrolytic solution was impregnated into a polypropylene porous body to produce a separator (separator 5) impregnated with the electrolytic solution.

次に、上記の負極、対極、非水電解液、およびセパレータを用いて、評価電池として、図１に示すボタン型二次電池を作製した。
この評価電池（以下、「評価電池Ａ」という）は、外装カップ１と外装缶３とはその周辺部において絶縁ガスケット６を介してかしめられた密閉構造である。そして、その内部に外装缶３の内面から順に、集電体８、リチウム金属箔４、セパレータ５、負極合剤層２、および電極板７が積層されている。 Next, a button-type secondary battery shown in FIG. 1 was produced as an evaluation battery using the negative electrode, the counter electrode, the nonaqueous electrolyte, and the separator.
This evaluation battery (hereinafter referred to as “evaluation battery A”) has a sealed structure in which the outer cup 1 and the outer can 3 are caulked with an insulating gasket 6 at the periphery thereof. A current collector 8, a lithium metal foil 4, a separator 5, a negative electrode mixture layer 2, and an electrode plate 7 are laminated in that order from the inner surface of the outer can 3.

このような評価電池Ａは、電解質液を含浸させたセパレータ５を、負極と対極との間に挟んで積層した後、負極を外装カップ１内に、また対極を外装缶３内に収容して、外装カップ１と外装缶３とを合わせた後、外装カップ１と外装缶３との周辺部を、絶縁ガスケット６を介してかしめ密閉して作製した。
この評価電池Ａは、本発明の負極と、リチウム金属箔を有する対極とから構成される電池である。 In such an evaluation battery A, the separator 5 impregnated with the electrolyte solution is stacked between the negative electrode and the counter electrode, and then the negative electrode is accommodated in the outer cup 1 and the counter electrode is accommodated in the outer can 3. After the outer cup 1 and the outer can 3 were combined, the peripheral portion of the outer cup 1 and the outer can 3 was produced by caulking and sealing via an insulating gasket 6.
This evaluation battery A is a battery composed of the negative electrode of the present invention and a counter electrode having a lithium metal foil.

以上のようにして作製された評価電池Ａについて、２５℃の温度下で下記のような充放電試験を行った。
０．９ｍＡの電流値で定電流充電を行い、回路電圧が０ｍＶに達した時点で定電圧充電に切り替え、さらに電流値が２０μＡになるまで充電を続けた後１２０分間休止した。
このとき、評価電池Ａの蓋を開け、負極を取り外し、その負極合剤層の厚さをマイクロメーターで測定し、充電前の厚さと比較し、電極の膨張率を次式から計算した。
また、上記と同様な方法で充電後の電極密度を測定した。その結果、実施例１においては１．５３ｇ／ｃｍ３であった。 The evaluation battery A produced as described above was subjected to the following charge / discharge test at a temperature of 25 ° C.
Constant current charging was performed at a current value of 0.9 mA, switching to constant voltage charging when the circuit voltage reached 0 mV, charging was continued until the current value reached 20 μA, and then rested for 120 minutes.
At this time, the lid of the evaluation battery A was opened, the negative electrode was removed, the thickness of the negative electrode mixture layer was measured with a micrometer, and compared with the thickness before charging, the expansion coefficient of the electrode was calculated from the following equation.
Further, the electrode density after charging was measured by the same method as described above. As a result, in Example 1, it was 1.53 g / cm 3 .

電極膨張率（％）＝（充電後の負極合剤層の厚さ−充電前の負極合剤層の厚さ）／充電前の負極合剤の厚さ×１００   Electrode expansion rate (%) = (thickness of negative electrode mixture layer after charging−thickness of negative electrode mixture layer before charging) / thickness of negative electrode mixture before charging × 100

計算した結果、電極膨張率は２０％であった。   As a result of calculation, the electrode expansion coefficient was 20%.

次に０．９ｍＡの電流値で、回路電圧が１．５Ｖに達するまで定電流放電を行った。このとき第１サイクルにおける通電量から充電容量と放電容量とを求めた。
なお、この試験では、リチウムイオンを負極材料の中へドープする過程を充電、負極材料から脱ドープする過程を放電とした。
その結果、放電容量は３５４ｍＡｈ／ｇであった。
また、この値と上記の充電後の電極密度の値から、充電後の体積当りの放電容量は５４２ｍＡｈ／ｃｍ３と算出された。 Next, constant current discharge was performed at a current value of 0.9 mA until the circuit voltage reached 1.5V. At this time, the charge capacity and the discharge capacity were obtained from the energization amount in the first cycle.
In this test, the process of doping lithium ions into the negative electrode material was charged, and the process of dedoping from the negative electrode material was discharge.
As a result, the discharge capacity was 354 mAh / g.
From this value and the value of the electrode density after charging, the discharge capacity per volume after charging was calculated to be 542 mAh / cm 3 .

次に上記の評価電池Ａの対極において用いたリチウム金属箔の代わりに、コバルト酸リチウム箔を用い、その他は評価電池Ａと同様とした評価電池（以下、「評価電池Ｂ」という）を作製した。
そして、上記と同じ条件の充放電を行い放電容量を求め、さらに充放電を行い放電容量を求めた。これを１００回繰り返し、第１回目の放電容量に対する第２回目以降の放電容量を百分率で求めた。この値を容量維持率とした。つまり、例えば、第１００回目の容量維持率は次の式で求めた値である。 Next, instead of the lithium metal foil used in the counter electrode of the evaluation battery A, an evaluation battery (hereinafter referred to as “evaluation battery B”) similar to the evaluation battery A was prepared using a lithium cobaltate foil. .
And charging / discharging of the same conditions as the above was performed, discharge capacity was calculated | required, and also charging / discharging was performed and discharge capacity was calculated | required. This was repeated 100 times, and the second and subsequent discharge capacities with respect to the first discharge capacity were determined as a percentage. This value was taken as the capacity retention rate. That is, for example, the 100th capacity retention rate is a value obtained by the following equation.

第１００回目の容量維持率（％）＝（第１００回目の放電容量／第１回目の放電容量）×１００   100th capacity retention rate (%) = (100th discharge capacity / first discharge capacity) × 100

第１回目から第１００回目の容量維持率を図２に示す（第１回目の容量維持率は１００％である）。
また、第１００回目の容量維持率を第１表に示す。実施例１においては９１％であった。 FIG. 2 shows the capacity maintenance rate from the first time to the 100th time (the capacity maintenance rate at the first time is 100%).
The 100th capacity retention rate is shown in Table 1. In Example 1, it was 91%.

＜実施例２＞
平均粒径２６μｍのメソカーボン小球体黒鉛化品と、平均粒径１１μｍのメソカーボン小球体黒鉛化品の粉砕品との質量比を６０：４０として混合したこと以外は、実施例１と同様の操作を行った。
各測定値、算出値を表１に示す。 <Example 2>
Example 1 except that the mass ratio of the mesocarbon microsphere graphitized product having an average particle size of 26 μm and the pulverized product of the mesocarbon microsphere graphitized product having an average particle size of 11 μm was mixed at 60:40. The operation was performed.
Table 1 shows the measured values and the calculated values.

＜実施例３＞
平均粒径２６μｍのメソカーボン小球体黒鉛化品と、平均粒径５μｍのメソカーボン小球体黒鉛化品の粉砕品（前記平均粒径２６μｍのメソカーボン小球体黒鉛化品を粉砕したもの）とを、質量比で７０：３０で混合したこと以外は、実施例１と同様の操作を行った。
各測定値、算出値を表１に示す。 <Example 3>
A mesocarbon microsphere graphitized product having an average particle size of 26 μm and a pulverized product of mesocarbon microsphere graphitized product having an average particle size of 5 μm (the pulverized mesocarbon microsphere graphitized product having an average particle size of 26 μm) The same operation as in Example 1 was performed except that mixing was performed at a mass ratio of 70:30.
Table 1 shows the measured values and the calculated values.

＜比較例１＞
平均粒径２６μｍのメソカーボン小球体黒鉛化品のみを用いたこと以外は、実施例１と同様の操作を行った。
各測定値、算出値を表１に示す。 <Comparative Example 1>
The same operation as in Example 1 was performed except that only mesocarbon microsphere graphitized products having an average particle size of 26 μm were used.
Table 1 shows the measured values and the calculated values.

＜比較例２＞
平均粒径２６μｍのメソカーボン小球体黒鉛化品と、平均粒径１１μｍのメソカーボン小球体黒鉛化品の粉砕品との質量比を８５：１５として混合したこと以外は、実施例１と同様の操作を行った。
各測定値、算出値を表１に示す。 <Comparative example 2>
The same as in Example 1 except that the mass ratio of the mesocarbon microsphere graphitized product having an average particle size of 26 μm and the pulverized product of the mesocarbon microsphere graphitized product having an average particle size of 11 μm was 85:15. The operation was performed.
Table 1 shows the measured values and the calculated values.

＜比較例３＞
平均粒径２６μｍのメソカーボン小球体黒鉛化品と、平均粒径２０μｍの天然黒鉛とを、質量比で８０：２０で混合したこと以外は、実施例１と同様の操作を行った。
各測定値、算出値を表１に示す。 <Comparative Example 3>
The same operation as in Example 1 was performed except that a mesocarbon microsphere graphitized product having an average particle size of 26 μm and natural graphite having an average particle size of 20 μm were mixed at a mass ratio of 80:20.
Table 1 shows the measured values and the calculated values.

充放電を１００回繰り返した結果、実施例３のメソカーボン小球体黒鉛化品に平均粒径５μｍのメソカーボン小球体黒鉛化品の粉砕品を混合（７０：３０）したものが、容量維持率９３％で最もよく、次いで実施例１のメソカーボン小球体黒鉛化品に平均粒径１１μｍのメソカーボン小球体黒鉛化品の粉砕品を混合（４０：６０）したもので、容量維持率が９１％、次いで実施例２のメソカーボン小球体黒鉛化品に平均粒径１１μｍのメソカーボン小球体黒鉛化品の粉砕品を混合（６０：４０）したもので、容量維持率が８９％であった。
一方、比較例１のメソカーボン小球体黒鉛化品のみでは、充放電を１００回繰り返した後の容量維持率が７５％であった。また、比較例２のメソカーボン小球体黒鉛化品に平均粒径１１μｍのメソカーボン小球体黒鉛化品の粉砕品を混合（８５：１５）したものは、同様に１００回繰り返した後の容量維持率が７９％であり、比較例３のメソカーボン小球体黒鉛化品に平均粒径２０μｍの天然黒鉛を混合（８０：２０）したものは、容量維持率が７３％であった。
以上より、実施例１、２、３のようにメソカーボン小球体黒鉛化品のアスペクト比を１．４０以下とすることにより、容量維持率を高位に維持することができることがわかる。 As a result of repeating charge and discharge 100 times, the mesocarbon microsphere graphitized product of Example 3 was mixed with a pulverized product of mesocarbon microsphere graphitized product having an average particle size of 5 μm (70:30), and the capacity retention rate It is the best at 93%, and then the mesocarbon microsphere graphitized product of Example 1 is mixed with a pulverized product of mesocarbon microsphere graphitized product having an average particle diameter of 11 μm (40:60). %, And then the mesocarbon microsphere graphitized product of Example 2 was mixed with a pulverized product of mesocarbon microsphere graphitized product having an average particle diameter of 11 μm (60:40), and the capacity retention rate was 89%. .
On the other hand, only the mesocarbon microsphere graphitized product of Comparative Example 1 had a capacity retention rate of 75% after 100 cycles of charge and discharge. In addition, in the case where the mesocarbon microsphere graphitized product of Comparative Example 2 was mixed with a pulverized product of mesocarbon microsphere graphitized product having an average particle diameter of 11 μm (85:15), the capacity was maintained after repeating 100 times in the same manner. The ratio was 79%, and the mesocarbon microsphere graphitized product of Comparative Example 3 was mixed with natural graphite having an average particle size of 20 μm (80:20), and the capacity retention rate was 73%.
From the above, it can be seen that the capacity retention ratio can be maintained at a high level by setting the aspect ratio of the mesocarbon microsphere graphitized product to 1.40 or less as in Examples 1, 2, and 3.

Figure 2007134276
Figure 2007134276

図１は、実施例および比較例で用いた評価電池の概略断面図である。FIG. 1 is a schematic cross-sectional view of an evaluation battery used in Examples and Comparative Examples. 図２は、実施例１、２、３、比較例１、２、３の容量維持率を比較した図である。FIG. 2 is a diagram comparing capacity retention rates of Examples 1, 2, and 3, and Comparative Examples 1, 2, and 3.

符号の説明Explanation of symbols

１ 外装カップ
２ 負極合剤層
３ 外装缶
４ リチウム金属箔
５ セパレータ
６ 絶縁ガスケット
７ 電極板
８ 集電体 DESCRIPTION OF SYMBOLS 1 Exterior cup 2 Negative electrode mixture layer 3 Exterior can 4 Lithium metal foil 5 Separator 6 Insulation gasket 7 Electrode plate 8 Current collector

Claims (6)

リチウムイオン二次電池負極の製造方法であって、
メソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤を調製する負極合剤調整工程と、
前記負極合剤を電極板に付け、前記負極合剤からなる層を有する電極板を形成する負極形成工程と、
前記負極合剤からなる層に、この層の密度を１．８ｇ／ｃｍ３以上とし、かつ、この層中の前記メソカーボン小球体黒鉛化品のアスペクト比を１．４以下とする圧力を加える加圧工程と
を具備するリチウムイオン二次電池負極の製造方法。 A method for producing a lithium ion secondary battery negative electrode, comprising:
A negative electrode mixture adjusting step of preparing a negative electrode mixture containing a mesocarbon microsphere graphitized product and a graphite particle having an average particle size smaller than this,
A negative electrode forming step of attaching the negative electrode mixture to an electrode plate and forming an electrode plate having a layer made of the negative electrode mixture;
A pressure is applied to the layer composed of the negative electrode mixture so that the density of the layer is 1.8 g / cm 3 or more and the aspect ratio of the mesocarbon microsphere graphitized product in the layer is 1.4 or less. The manufacturing method of the lithium ion secondary battery negative electrode which comprises a pressurization process. 前記負極合剤において、前記メソカーボン小球体黒鉛化品と前記黒鉛質粒子との合計質量に対する、前記メソカーボン小球体黒鉛化品の質量割合が、２５質量％超、７５質量％以下である、請求項１に記載のリチウムイオン二次電池負極の製造方法。   In the negative electrode mixture, a mass ratio of the mesocarbon microsphere graphitized product to a total mass of the mesocarbon microsphere graphitized product and the graphite particles is more than 25 mass% and 75 mass% or less. The manufacturing method of the lithium ion secondary battery negative electrode of Claim 1. 前記黒鉛質粒子が非燐片状黒鉛質粒子である請求項１または２に記載のリチウムイオン二次電池負極の製造方法。   The method for producing a negative electrode for a lithium ion secondary battery according to claim 1 or 2, wherein the graphite particles are non-flaky graphite particles. 前記メソカーボン小球体黒鉛化品の平均粒径が５〜１００μｍであり、前記黒鉛質粒子の平均粒径が１〜３０μｍである請求項１〜３のいずれかに記載のリチウムイオン二次電池負極の製造方法。   The lithium ion secondary battery negative electrode according to any one of claims 1 to 3, wherein the mesocarbon microsphere graphitized product has an average particle size of 5 to 100 µm, and the graphite particles have an average particle size of 1 to 30 µm. Manufacturing method. アスペクト比が１．４以下であるメソカーボン小球体黒鉛化品と、これよりも平均粒径が小さい黒鉛質粒子とを含む負極合剤からなり、密度が１．８ｇ／ｃｍ３以上である層を電極板上に有する、リチウムイオン二次電池負極。 A layer comprising a negative electrode mixture containing a mesocarbon microsphere graphitized product having an aspect ratio of 1.4 or less and a graphitic particle having an average particle size smaller than that, and having a density of 1.8 g / cm 3 or more A negative electrode for a lithium ion secondary battery. 請求項５に記載のリチウムイオン二次電池負極を備えるリチウムイオン二次電池。   A lithium ion secondary battery comprising the lithium ion secondary battery negative electrode according to claim 5.
JP2005328658A 2005-11-14 2005-11-14 Method for producing negative electrode for lithium ion secondary battery Expired - Fee Related JP5172089B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2005328658A JP5172089B2 (en) 2005-11-14 2005-11-14 Method for producing negative electrode for lithium ion secondary battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2005328658A JP5172089B2 (en) 2005-11-14 2005-11-14 Method for producing negative electrode for lithium ion secondary battery

Publications (2)

Publication Number Publication Date
JP2007134276A true JP2007134276A (en) 2007-05-31
JP5172089B2 JP5172089B2 (en) 2013-03-27

Family

ID=38155756

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2005328658A Expired - Fee Related JP5172089B2 (en) 2005-11-14 2005-11-14 Method for producing negative electrode for lithium ion secondary battery

Country Status (1)

Country Link
JP (1) JP5172089B2 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009141991A1 (en) * 2008-05-23 2009-11-26 パナソニック株式会社 Electrode for non-aqueous electrolyte secondary battery, manufacturing method therefor, and non-aqueous electrolyte secondary battery
WO2010146832A1 (en) * 2009-06-16 2010-12-23 パナソニック株式会社 Process for production of negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery utilizing the negative electrode
JP2011009051A (en) * 2009-06-25 2011-01-13 Jfe Chemical Corp Negative electrode material for lithium ion secondary battery, lithium ion secondary battery negative electrode, and lithium ion secondary battery
JP2013224927A (en) * 2012-03-23 2013-10-31 Sumika Chemical Analysis Service Ltd Observation sample, observation sample preparation method, and observation method
KR20140121445A (en) 2012-03-02 2014-10-15 제이에프이 케미칼 가부시키가이샤 Nagative electrode material for lithium ion secondary batteries, nagative electrode for lithium ion secondary batteries, and lithium ion secondary battery

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003297353A (en) * 2002-03-29 2003-10-17 Nec Corp Negative electrode for secondary battery, secondary battery using such negative electrode, and manufacturing method for negative electrode
JP2004127913A (en) * 2002-07-31 2004-04-22 Matsushita Electric Ind Co Ltd Lithium secondary battery

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003297353A (en) * 2002-03-29 2003-10-17 Nec Corp Negative electrode for secondary battery, secondary battery using such negative electrode, and manufacturing method for negative electrode
JP2004127913A (en) * 2002-07-31 2004-04-22 Matsushita Electric Ind Co Ltd Lithium secondary battery

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009141991A1 (en) * 2008-05-23 2009-11-26 パナソニック株式会社 Electrode for non-aqueous electrolyte secondary battery, manufacturing method therefor, and non-aqueous electrolyte secondary battery
JP2009283354A (en) * 2008-05-23 2009-12-03 Panasonic Corp Electrode for nonaqueous electrolyte secondary battery, manufacturing method thereof, and nonaqueous electrolyte secondary battery
WO2010146832A1 (en) * 2009-06-16 2010-12-23 パナソニック株式会社 Process for production of negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery utilizing the negative electrode
CN102150304A (en) * 2009-06-16 2011-08-10 松下电器产业株式会社 Method of producing negative electrode for non-aqueous electrolyte secondary battery, negative electrode, and non-aqueous electrolyte secondary battery using the same
JP2011009051A (en) * 2009-06-25 2011-01-13 Jfe Chemical Corp Negative electrode material for lithium ion secondary battery, lithium ion secondary battery negative electrode, and lithium ion secondary battery
KR20140121445A (en) 2012-03-02 2014-10-15 제이에프이 케미칼 가부시키가이샤 Nagative electrode material for lithium ion secondary batteries, nagative electrode for lithium ion secondary batteries, and lithium ion secondary battery
JP2013224927A (en) * 2012-03-23 2013-10-31 Sumika Chemical Analysis Service Ltd Observation sample, observation sample preparation method, and observation method

Also Published As

Publication number Publication date
JP5172089B2 (en) 2013-03-27

Similar Documents

Publication Publication Date Title
KR101733323B1 (en) Negative electrode material for lithium ion secondary batteries, method for producing same, negative electrode for lithium ion secondary batteries using same, and lithium ion secondary battery
CN107078288B (en) Graphite particle for negative electrode material of lithium ion secondary battery, negative electrode of lithium ion secondary battery, and lithium ion secondary battery
JP4040381B2 (en) Composite graphite particles, method for producing the same, negative electrode for lithium ion secondary battery and lithium ion secondary battery
US20070111102A1 (en) Negative electrode for non-aqueous electrolyte secondary batteries, non-aqueous electrolyte secondary battery having the electrode, and method for producing negative electrode for non-aqueous electrolyte secondary batteries
JP4595145B2 (en) Non-aqueous electrolyte battery
JP6585238B2 (en) Method for producing carbonaceous coated graphite particles for negative electrode material of lithium ion secondary battery
KR100975875B1 (en) Cathode active material, method of preparing the same, and cathode and lithium battery containing the material
KR102065256B1 (en) Silicone based negative active material, preparing method of the same and lithium ion secondary battery including the same
JP2003132889A (en) Anode material for lithium ion secondary battery and its manufacturing method
JP5172089B2 (en) Method for producing negative electrode for lithium ion secondary battery
JP4354723B2 (en) Method for producing graphite particles
JP2007173156A (en) Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery
JP4152279B2 (en) Negative electrode for lithium ion secondary battery and lithium ion secondary battery
JP4996827B2 (en) Metal-graphite composite particles for negative electrode of lithium ion secondary battery and manufacturing method thereof, negative electrode material and negative electrode for lithium ion secondary battery, and lithium ion secondary battery
JP4870419B2 (en) Negative electrode material for lithium ion secondary battery and method for producing the same, lithium ion secondary battery negative electrode and lithium ion secondary battery
JP2004063411A (en) Complex graphite material, its manufacturing method, negative electrode for lithium ion secondary battery, and lithium ion secondary battery
JP5066132B2 (en) Polycrystalline mesocarbon microsphere graphitized product, negative electrode active material, and lithium ion secondary battery
JP2002222651A (en) Non-aqueous electrolyte secondary battery
JP7189109B2 (en) Method for producing carbonaceous-coated graphite particles
JP2004047487A (en) Cathode for lithium secondary battery and lithium secondary battery using the same
JP2000294243A (en) Carbon powder for lithium secondary battery negative electrode, manufacture therefor, negative electrode for lithium secondary battery and lithium secondary battery
JP2007066633A (en) Current collector, negative electrode, and battery
JP4643165B2 (en) Carbon material, negative electrode material for lithium ion secondary battery, negative electrode and lithium ion secondary battery
JP4335596B2 (en) Method for producing polycrystalline mesocarbon microsphere graphitized product
WO2016194355A1 (en) Carbonaceous coated graphite particles for negative-electrode material of lithium-ion secondary cell, negative electrode for lithium-ion secondary cell, and lithium-ion secondary cell

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20081024

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20110916

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20111018

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20120724

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20121009

A911 Transfer to examiner for re-examination before appeal (zenchi)

Free format text: JAPANESE INTERMEDIATE CODE: A911

Effective date: 20121018

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

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20121225

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20121226

R150 Certificate of patent or registration of utility model

Ref document number: 5172089

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

LAPS Cancellation because of no payment of annual fees