JP2004158205A - Manufacturing method of non-aqueous electrolyte secondary battery - Google Patents

Manufacturing method of non-aqueous electrolyte secondary battery Download PDF

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Publication number
JP2004158205A
JP2004158205A JP2002319998A JP2002319998A JP2004158205A JP 2004158205 A JP2004158205 A JP 2004158205A JP 2002319998 A JP2002319998 A JP 2002319998A JP 2002319998 A JP2002319998 A JP 2002319998A JP 2004158205 A JP2004158205 A JP 2004158205A
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graphite
negative electrode
bulk density
active material
mixture
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JP2002319998A
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Japanese (ja)
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Jo Sasaki
丈 佐々木
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Japan Storage Battery Co Ltd
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Japan Storage Battery Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • 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 manufacturing method of a non-aqueous electrolyte secondary battery in which energy density can be increased and also battery performance can be improved by using as a negative electrode active material a mixture in which a graphite having high bulk density and a graphite having low bulk density are mixed. <P>SOLUTION: A mixture of graphite having a bulk density of 0.4 g/cc or more in which a graphite having a bulk density of 0.5 g/cc or more and of which graphite particle C<SB>1</SB>becomes spherical or the like and a graphite having a bulk density of 0.25 g/cc or less and of which graphite particle C<SB>2</SB>becomes needle shape or flake shape are mixed is made as a negative electrode active material, and a negative electrode active material mixture 12b in which at least a binder is added to this negative electrode active material is carried by the negative electrode 12. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、負極電極の負極活物質に黒鉛を用いた非水電解質二次電池の製造方法に関する。
【０００２】
【従来の技術】
非水電解質二次電池では、負極活物質に金属イオンの吸蔵体として各種炭素材料を用いることがある。そして、この炭素材料の中でも特に黒鉛（グラファイト）は、比較的安価で取り扱いが容易であり、充放電電位がリチウム金属の溶出電位に近く、充放電の可逆性に優れていることから、リチウムイオン二次電池等に広く用いられている。
【０００３】
上記黒鉛を負極活物質として、高エネルギー密度の非水電解質二次電池を製造するには、負極への充填性が高い黒鉛を用いる必要がある。この黒鉛の充填性を表す指標の一つとしてかさ密度があり、黒鉛自体の真密度は約２．２ｇ／ｃｃであるが、この黒鉛の粒子形状等を調整することにより、適宜のかさ密度の黒鉛を製造することができる。例えば、図３に示すように、黒鉛粒子Ｃ１を球状に近い大きな塊とした場合には、１．０ｇ／ｃｃ程度のかさ密度の高い黒鉛となり、図４に示すように、黒鉛粒子Ｃ２の形状を針状やフレーク状とした場合には、０．１８ｇ／ｃｃ程度のかさ密度の低い黒鉛となる。
【０００４】
上記黒鉛を負極活物質として用いるには、この黒鉛にバインダ等を添加してペースト状の合材とする。そして、この合材を負極の集電基材となる銅箔等の表面に塗布し乾燥させて圧密化することによりこの負極に担持させる。
【０００５】
【発明が解決しようとする課題】
ところが、かさ密度の高い黒鉛は、バインダを添加して合材としたときに、このバインダを黒鉛粒子間に取り込み難く、合材のペースト中で沈降し易くなる。このため、電池のエネルギー密度を高めるために、かさ密度の高い黒鉛を使用すると、合材中に黒鉛とバインダが不均一に分布するようになるので、良好な充放電特性が得られなくなるという問題があった。また、このような分布の不均一があると、充放電により負極活物質が膨張収縮を繰り返した場合に、合材の電気抵抗が増加し易くなり、寿命性能が低下するという問題もあった。
【０００６】
なお、逆にかさ密度の低い黒鉛を使用しても、圧密化によって圧迫することにより多孔度を低下させて充填性を高めることはできるが、針状やフレーク状の黒鉛粒子Ｃ２がこの圧密化によって集電基材の表面に平行に配向されるようになるために、電解液が浸透し難くなってエネルギー密度を十分に高めることができない。
【０００７】
本発明は、かかる事情に対処するためになされたものであり、かさ密度の高い黒鉛と低い黒鉛を混合して負極活物質として用いることにより、エネルギー密度を高めると共に電池性能も向上させることができる非水電解質二次電池の製造方法を提供することを目的としている。
【０００８】
【課題を解決するための手段】
請求項１の非水電解質二次電池の製造方法は、かさ密度が０．５ｇ／ｃｃ以上の１種以上の黒鉛とかさ密度が０．２５ｇ／ｃｃ以下の１種以上の黒鉛とを混合し、かさ密度を０．４ｇ／ｃｃ以上とした黒鉛混合物を負極活物質の主成分とした合材を負極に担持させたことを特徴とする。
【０００９】
請求項１の発明によれば、かさ密度が高い黒鉛にかさ密度の低い黒鉛を混合することにより、かさ密度の高い球状等の黒鉛粒子の間に、かさ密度の低い針状やフレーク状等の黒鉛粒子が混入するので、これらの黒鉛混合物の粒子間にバインダが入り込み易くなり、合材中で黒鉛とバインダが不均一に分布するようなことがなくなる。即ち、バインダは、大きな球状等からなる黒鉛粒子だけの間の広い間隙には入り込み難いが、この間隙に針状やフレーク状等からなる黒鉛粒子が混入することにより、これらの粒子間に容易に入り込むことができるようになる。これに対して、例えば小さい球状や太いフレーク状の粒子形状を有し、かさ密度が０．４ｇ／ｃｃ程度となる黒鉛だけを用いた場合には、大きい球状の粒子からなる黒鉛だけを用いた場合よりは多少改善されるが、球状等と針状、フレーク状等の黒鉛粒子を混合した場合ほど粒子間にバインダが入り込み易くなるようなことはない。従って、このような黒鉛混合物を用いることにより、合材中に黒鉛とバインダとが不均一に分布するようなことがなくなるので良好な電池特性を得ることができる。しかも、このような黒鉛混合物は、全体では０．４ｇ／ｃｃ以上の比較的高いかさ密度となるので、負極への充填性を十分に高めることができ、非水電解質二次電池の高エネルギー密度化を損なうようなことがなくなる。
【００１０】
なお、上記非水電解質二次電池の製造方法では、合材が負極の集電基材となる金属箔の表面に塗布されて圧密化されることにより担持されるようにすることが好ましい。このようにすれば、金属箔の表面に塗布された合材が圧密化されるので、これにより多孔度を例えば３０〜４５％の範囲内の最適な値に調整することができ、電池特性を損なわない範囲内でエネルギー密度を高めることができる。また、粒子形状が針状やフレーク状等の黒鉛は、圧密化により伸展し易い特徴を有するため、粒子形状が球状等の黒鉛と混合して圧密化することにより、合材の導電性を高めることもできるようになる。
【００１１】
【発明の実施の形態】
以下、本発明の実施形態について図面を参照して説明する。
【００１２】
図１〜図２は本発明の一実施形態を示すものであって、図１は黒鉛混合物に混合されたかさ密度の高い黒鉛粒子Ｃ１とかさ密度の低い黒鉛粒子Ｃ２を示す拡大図、図２は大型の非水電解質二次電池に用いられる長円筒形巻回型の発電要素の構成を示す組み立て斜視図である。
【００１３】
大型の非水電解質二次電池に用いられる長円筒形巻回型の発電要素１の構成例を図２に示す。この発電要素１は、正極１１と負極１２をセパレータ１３を介して長円筒形に巻回している。正極１１は、集電基材となる帯状のアルミニウム箔１１ａの表面に正極活物質合材１１ｂを担持させたものである。負極１２は、集電基材となる帯状の銅箔１２ａの表面に負極活物質合材１２ｂを担持させたものである。なお、これらの正極１１と負極１２は、上下の側端部に合材１１ｂ，１２ｂを塗布しない未塗工部を設けておき、この未塗工部でアルミニウム箔１１ａと銅箔１２ａが露出するようにして、発電要素１の両端部から端子への接続を行うようにしている。
【００１４】
正極活物質合材１１ｂは、リチウムコバルト複合酸化物等のリチウム含有複合酸化物を正極活物質とし、これにバインダや導電補助剤を添加すると共に溶剤を加えてペースト状にしたものであり、アルミニウム箔１１ａの表面に塗布し乾燥させることにより正極１１に担持させている。
【００１５】
負極活物質合材１２ｂは、負極活物質として、かさ密度が０．５ｇ／ｃｃ以上の黒鉛とかさ密度が０．２５ｇ／ｃｃ以下の黒鉛とを混合した、かさ密度が０．４ｇ／ｃｃ以上の黒鉛混合物を用いる。図３に示したように、かさ密度が０．５ｇ／ｃｃ以上の黒鉛の黒鉛粒子Ｃ１は、一般には球状に近い大きな塊となる。また、図４に示したように、かさ密度が０．２５ｇ／ｃｃ以下の黒鉛の黒鉛粒子Ｃ２は、一般には針状やフレーク状のものとなる。これらの黒鉛粒子Ｃ１，Ｃ２が混合されると、図１に示すように、かさ密度の高い黒鉛粒子Ｃ１の間の広い間隙に、かさ密度の低い黒鉛粒子Ｃ２が混入するので、添加するバインダがこのかさ密度の低い黒鉛粒子Ｃ２間やこれとかさ密度の高い黒鉛粒子Ｃ１との間に入り込み易くなり、全体としてこれらの黒鉛粒子Ｃ１，Ｃ２の間にバインダが均一に広がるようになる。
【００１６】
負極活物質合材１２ｂは、上記負極活物質にバインダを添加すると共に溶剤を加えてペースト状にしたものである。バインダとしては、ポリフッ化ビニリデン等のように非水電解液に溶解し難いものが用いられる。このバインダの添加率は、負極活物質合材１２ｂに対して２〜１０ｗｔ％の範囲内が適当である。バインダの添加率が２ｗｔ％未満になると、負極活物質合材１２ｂ中の黒鉛粒子Ｃ１，Ｃ２間や負極１２の銅箔１２ａの表面との結合が不十分になり、この負極１２から負極活物質合材１２ｂが脱落するおそれがある。また、バインダの添加率が１０ｗｔ％を超えると、負極活物質合材１２ｂの導電性が低下すると共に、黒鉛の含有量が減少するためにエネルギー密度も低下することになる。
【００１７】
上記負極活物質合材１２ｂは、銅箔１２ａの表面に塗布し乾燥させて圧密化することにより負極１２に担持させている。圧密化は、ローラ等を用いることにより銅箔１２ａの表面に塗布された負極活物質合材１２ｂを圧迫するものであり、これにより負極活物質合材１２ｂの多孔度が３０〜４５％の範囲内となるようにしている。多孔度が大きくなりすぎるとエネルギー密度が低下し、小さくなりすぎると充放電特性が低下する。
【００１８】
上記負極活物質合材１２ｂを担持させた負極１２は、ポリエチレン樹脂の微多孔膜からなるセパレータ１３を介し正極１１と重ね合わせて巻回することにより発電要素１が作製される。そして、この発電要素１の両端面にはみ出したアルミニウム箔１１ａと銅箔１２ａをそれぞれ正負極の端子に接続すると共に、この発電要素１を電池容器に収納し非水電解液を注入して密閉することにより非水電解質二次電池が製造される。
【００１９】
上記構成により本実施形態の非水電解質二次電池の製造方法は、負極１２の負極活物質合材１２ｂに用いる負極活物質の黒鉛が、かさ密度の高い黒鉛粒子Ｃ１とかさ密度の低い黒鉛粒子Ｃ２とを混合した黒鉛混合物からなるので、これらの黒鉛粒子Ｃ１，Ｃ２の間にバインダが入り込み易くなり、負極活物質合材１２ｂ中に黒鉛とバインダが均一に分布するようになって、良好な電池特性を得ることができる。しかも、これらかさ密度の異なる黒鉛粒子Ｃ１，Ｃ２が混合した黒鉛混合物は、全体でも０．４ｇ／ｃｃ以上の比較的高いかさ密度となるような割合で配合されるので、負極１２への充填性を十分に高めることができる。さらに、この負極活物質合材１２ｂは、かさ密度の高い黒鉛粒子Ｃ１の間にかさ密度の低い黒鉛粒子Ｃ２が混入しているので、圧密化を行っても、このかさ密度の低い黒鉛粒子Ｃ２が銅箔１２ａの表面に平行に配向されてしまうようなことがなくなり、電解液の浸透が妨げられるおそれも生じない。
【００２０】
なお、上記実施形態では、かさ密度が高い黒鉛粒子Ｃ１として球状に近い大きな塊の粒子形状を示したが、黒鉛のかさ密度が０．５ｇ／ｃｃ以上であれば、どのような粒子形状であっても間隙にバインダが入り込み難くなるので、同様の効果を得ることができる。また、かさ密度が低い黒鉛粒子Ｃ２として針状やフレーク状の粒子形状を示したが、黒鉛のかさ密度が０．２５ｇ／ｃｃ以下であれば、どのような粒子形状であっても、かさ密度の高い黒鉛粒子Ｃ１の間に入り込むことができるので、同様の効果を得ることができる。
【００２１】
また、上記実施形態では、黒鉛混合物として、かさ密度の高いものを１種と低いものを１種ずつ混合する場合を示したが、いずれのかさ密度の黒鉛であっても、２種以上用いることができる。さらに、上記実施形態では、黒鉛混合物をそのまま負極活物質として用いたが、このような黒鉛混合物を主成分とするものであれば、他の添加物を含んだ負極活物質を用いることもできる。さらに、上記実施形態では、負極活物質にバインダを添加し溶剤を加えてペースト状の負極活物質合材１２ｂを作製したが、この負極活物質に少なくともバインダを添加した負極活物質合材１２ｂであればよく、その他の添加物の有無は問わない。
【００２２】
また、上記実施形態では、負極１２をセパレータ１３を介して正極１１と共に長円筒形に巻回した発電要素１について示したが、巻回の形状は任意であり、積層型の発電要素にも同様に実施可能である。さらに、上記実施形態では、正極活物質にリチウム含有複合酸化物を用いた非水電解質二次電池について示したが、他の正極活物質を用いる非水電解質二次電池の製造方法にも同様に実施可能である。
【００２３】
【発明の効果】
以上の説明から明らかなように、本発明の非水電解質二次電池の製造方法によれば、負極活物質としてかさ密度の高い黒鉛にかさ密度の低い黒鉛を混合した黒鉛混合物を用いることにより、非水電解質二次電池の高エネルギー密度化を図ると共に、電池特性も向上させることができるようになる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示すものであって、黒鉛混合物に混合されたかさ密度の高い黒鉛粒子Ｃ１とかさ密度の低い黒鉛粒子Ｃ２を示す拡大図である。
【図２】本発明の一実施形態を示すものであって、大型の非水電解質二次電池に用いられる長円筒形巻回型の発電要素の構成を示す組み立て斜視図である。
【図３】従来例を示すものであって、かさ密度の高い黒鉛の黒鉛粒子Ｃ１を示す拡大図である。
【図４】従来例を示すものであって、かさ密度の低い黒鉛の黒鉛粒子Ｃ２を示す拡大図である。
【符号の説明】
Ｃ１ かさ密度の高い黒鉛の黒鉛粒子
Ｃ２ かさ密度の低い黒鉛の黒鉛粒子
１２ 負極
１２ａ 銅箔
１２ｂ 負極活物質合材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery using graphite as a negative electrode active material of a negative electrode.
[0002]
[Prior art]
In a non-aqueous electrolyte secondary battery, various carbon materials may be used as a negative electrode active material as a metal ion occlusion material. Among these carbon materials, graphite (graphite) is relatively inexpensive and easy to handle. The charge / discharge potential is close to the elution potential of lithium metal, and the charge / discharge reversibility is excellent. Widely used for secondary batteries and the like.
[0003]
In order to manufacture a non-aqueous electrolyte secondary battery having a high energy density using the above graphite as a negative electrode active material, it is necessary to use graphite having a high filling property to the negative electrode. Bulk density is one of the indices indicating the fillability of the graphite, and the true density of the graphite itself is about 2.2 g / cc. By adjusting the particle shape and the like of the graphite, an appropriate bulk density can be obtained. Graphite can be manufactured. For example, as shown in FIG. 3, when the graphite particles C 1 was large clumps close to spherical, it becomes high bulk density of about 1.0 g / cc graphite, as shown in FIG. 4, the graphite particles C 2 When the shape is a needle shape or a flake shape, graphite having a low bulk density of about 0.18 g / cc is obtained.
[0004]
In order to use the graphite as a negative electrode active material, a binder or the like is added to the graphite to form a paste-like mixture. Then, this mixture is applied to the surface of a copper foil or the like serving as a current collecting base material of the negative electrode, dried and consolidated to be supported on the negative electrode.
[0005]
[Problems to be solved by the invention]
However, graphite having a high bulk density, when a binder is added to form a mixture, makes it difficult for this binder to be taken in between graphite particles, and tends to settle in the paste of the mixture. For this reason, when graphite having a high bulk density is used to increase the energy density of the battery, the graphite and the binder are non-uniformly distributed in the mixture, so that good charge / discharge characteristics cannot be obtained. was there. In addition, when the distribution is non-uniform, when the negative electrode active material repeatedly expands and contracts due to charge and discharge, the electric resistance of the mixture tends to increase, and there is a problem that the life performance is reduced.
[0006]
Even using graphite low bulk density Conversely, although it is possible to enhance the filling property by lowering the porosity by compression by compaction, acicular or flaky graphite particles C 2 is the compaction As a result, the electrolyte becomes difficult to penetrate, and the energy density cannot be sufficiently increased.
[0007]
The present invention has been made in order to cope with such circumstances, and by using a mixture of graphite having a high bulk density and low graphite as a negative electrode active material, it is possible to increase energy density and improve battery performance. An object of the present invention is to provide a method for manufacturing a non-aqueous electrolyte secondary battery.
[0008]
[Means for Solving the Problems]
In the method for producing a nonaqueous electrolyte secondary battery according to claim 1, one or more types of graphite having a bulk density of 0.5 g / cc or more and one or more types of graphite having a bulk density of 0.25 g / cc or less are mixed. The negative electrode is characterized in that a mixture containing a graphite mixture having a bulk density of 0.4 g / cc or more as a main component of the negative electrode active material is supported on the negative electrode.
[0009]
According to the invention of claim 1, by mixing graphite having a low bulk density with graphite having a high bulk density, needle-like or flake-like particles having a low bulk density are interposed between graphite particles having a high bulk density. Since the graphite particles are mixed, the binder easily enters between the particles of the graphite mixture, thereby preventing the graphite and the binder from being unevenly distributed in the mixture. That is, the binder does not easily enter a wide gap between only the graphite particles having a large spherical shape or the like, but the graphite particles having a needle shape or a flake shape are easily mixed into these gaps. You will be able to get in. On the other hand, for example, when only graphite having a small spherical or thick flake-like particle shape and a bulk density of about 0.4 g / cc is used, only graphite consisting of large spherical particles is used. Although it is slightly improved as compared with the case, the binder does not easily enter between the particles as in the case where graphite particles such as spherical particles and needle-like or flake-like particles are mixed. Therefore, by using such a graphite mixture, non-uniform distribution of the graphite and the binder in the composite material is eliminated, so that good battery characteristics can be obtained. In addition, such a graphite mixture has a relatively high bulk density of 0.4 g / cc or more as a whole, so that the filling property of the negative electrode can be sufficiently increased, and the high energy density of the nonaqueous electrolyte secondary battery can be improved. It does not impair conversion.
[0010]
In the method for producing a nonaqueous electrolyte secondary battery, it is preferable that the mixture is applied to the surface of a metal foil serving as a current collecting base material of the negative electrode, and is consolidated to be supported. In this way, the mixture applied to the surface of the metal foil is compacted, so that the porosity can be adjusted to an optimal value within a range of, for example, 30 to 45%, and the battery characteristics can be improved. The energy density can be increased within a range that does not impair. In addition, graphite having a needle shape or a flake shape, which has a characteristic of being easily extensible by compaction, has a particle shape mixed with graphite such as a spherical shape to be compacted, thereby enhancing the conductivity of the mixture. You can also do things.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
Figures 1-2, there is shown an embodiment of the present invention, FIG. 1 is an enlarged view showing a lower graphite particles C 2 high graphite particles C 1 and bulk density bulk density mixed graphite mixture, FIG. 2 is an assembled perspective view showing a configuration of a long cylindrical wound type power generating element used for a large non-aqueous electrolyte secondary battery.
[0013]
FIG. 2 shows a configuration example of a long cylindrical wound type power generating element 1 used for a large non-aqueous electrolyte secondary battery. In the power generation element 1, a positive electrode 11 and a negative electrode 12 are wound in a long cylindrical shape with a separator 13 interposed therebetween. The positive electrode 11 is obtained by supporting a positive electrode active material mixture 11b on the surface of a strip-shaped aluminum foil 11a serving as a current collecting base material. The negative electrode 12 is obtained by supporting a negative electrode active material mixture 12b on the surface of a strip-shaped copper foil 12a serving as a current collecting base material. The positive electrode 11 and the negative electrode 12 are provided with uncoated portions where the mixture materials 11b and 12b are not applied at upper and lower side edges, and the aluminum foil 11a and the copper foil 12a are exposed at the uncoated portions. In this way, connection is made from both ends of the power generating element 1 to the terminals.
[0014]
The positive electrode active material mixture 11b is obtained by using a lithium-containing composite oxide such as a lithium-cobalt composite oxide as a positive electrode active material, adding a binder and a conductive auxiliary agent, and adding a solvent to the paste to form a paste. It is applied to the surface of the foil 11a and dried to be supported on the positive electrode 11.
[0015]
The negative electrode active material mixture 12b is a mixture of graphite having a bulk density of 0.5 g / cc or more and graphite having a bulk density of 0.25 g / cc or less as a negative electrode active material, and having a bulk density of 0.4 g / cc or more. Using a graphite mixture. As shown in FIG. 3, the graphite particles C 1 of the above graphite bulk density of 0.5 g / cc is a great mass close to spherical in general. Further, as shown in FIG. 4, the graphite particles C 2 of less graphite bulk density of 0.25 g / cc is generally it becomes acicular or flaky. When these graphite particles C 1 and C 2 are mixed, as shown in FIG. 1, graphite particles C 2 having a low bulk density are mixed in a wide gap between the graphite particles C 1 having a high bulk density. binder added becomes easily enter between the high graphite particle C 1 lower graphite particles C 2 and between this and bulk density of this bulk density, binder uniformly between these graphite particles C 1, C 2 as a whole It will spread to.
[0016]
The negative electrode active material mixture 12b is obtained by adding a binder and a solvent to the negative electrode active material to form a paste. As the binder, one hardly soluble in a non-aqueous electrolyte such as polyvinylidene fluoride is used. The addition rate of the binder is suitably in the range of 2 to 10 wt% with respect to the negative electrode active material mixture 12b. When the addition ratio of the binder is less than 2 wt%, the bonding between the graphite particles C 1 and C 2 in the negative electrode active material mixture 12 b and the surface of the copper foil 12 a of the negative electrode 12 becomes insufficient, and the negative electrode 12 The active material mixture 12b may fall off. On the other hand, when the addition ratio of the binder exceeds 10% by weight, the conductivity of the negative electrode active material mixture 12b decreases, and the energy density also decreases because the graphite content decreases.
[0017]
The negative electrode active material mixture 12b is applied to the surface of the copper foil 12a, dried and consolidated to be supported on the negative electrode 12. The consolidation is to press the negative electrode active material mixture 12b applied to the surface of the copper foil 12a by using a roller or the like, whereby the porosity of the negative electrode active material mixture 12b is in the range of 30 to 45%. I'm trying to be inside. If the porosity is too large, the energy density is reduced, and if it is too small, the charge / discharge characteristics are reduced.
[0018]
The negative electrode 12 supporting the negative electrode active material mixture 12b is superposed and wound on the positive electrode 11 via a separator 13 formed of a microporous polyethylene resin film, whereby the power generating element 1 is manufactured. Then, the aluminum foil 11a and the copper foil 12a protruding from both end surfaces of the power generating element 1 are respectively connected to positive and negative terminals, and the power generating element 1 is housed in a battery container, and a non-aqueous electrolyte is injected and sealed. Thereby, a non-aqueous electrolyte secondary battery is manufactured.
[0019]
Method of manufacturing a nonaqueous electrolyte secondary battery of the present embodiment by the above configuration, the graphite of the negative electrode active material used for the negative electrode active material cause material 12b of the negative electrode 12 is less high graphite particles C 1 and bulk density bulk density graphite since the graphite-made mixture obtained by mixing the particles C 2, easily enter the binder between these graphite particles C 1, C 2, so as graphite and a binder is uniformly distributed in the anode active material cause material 12b As a result, good battery characteristics can be obtained. In addition, the graphite mixture in which the graphite particles C 1 and C 2 having different bulk densities are mixed is blended at a ratio so as to have a relatively high bulk density of 0.4 g / cc or more as a whole. The filling property can be sufficiently improved. Further, the anode active material cause material 12b, since the graphite particles C 2 low bulk density between graphite particles high bulk density C 1 is mixed, even if the compaction, a low the bulk density graphite prevents particles C 2 is that would be oriented parallel to the surface of the copper foil 12a, penetration of the electrolyte contact it does not occur that interfere.
[0020]
In the above embodiment, although the particle shape of the large masses close to spherical as the bulk density is high graphite particles C 1, if the bulk density of graphite 0.5 g / cc or more, in any particle shape Even if there is, it is difficult for the binder to enter the gap, so that the same effect can be obtained. Further, although the needle and flaky particle shape bulk density as low graphite particles C 2, if the bulk density of the graphite is less than 0.25 g / cc, whatever the particle shape, bulk it is possible to enter between the dense graphite particles C 1, it is possible to obtain the same effect.
[0021]
Further, in the above-described embodiment, the case where one kind of high bulk density and one kind of low bulk density are mixed is described as the graphite mixture, but two or more kinds of graphite of any bulk density are used. Can be. Further, in the above embodiment, the graphite mixture is used as it is as the negative electrode active material, but a negative electrode active material containing other additives can also be used as long as such a graphite mixture is the main component. Further, in the above embodiment, a paste was added to the negative electrode active material and a solvent was added to prepare a paste-like negative electrode active material mixture 12b. However, the negative electrode active material mixture 12b obtained by adding at least a binder to this negative electrode active material was used. It does not matter whether or not other additives are present.
[0022]
Further, in the above embodiment, the power generating element 1 in which the negative electrode 12 is wound together with the positive electrode 11 through the separator 13 into an elongated cylindrical shape is shown, but the winding shape is arbitrary, and the same applies to the stacked power generating element. Can be implemented. Furthermore, in the above embodiment, the non-aqueous electrolyte secondary battery using the lithium-containing composite oxide as the positive electrode active material has been described. However, the same applies to a method for manufacturing a non-aqueous electrolyte secondary battery using another positive electrode active material. It is feasible.
[0023]
【The invention's effect】
As is apparent from the above description, according to the method for producing a nonaqueous electrolyte secondary battery of the present invention, by using a graphite mixture obtained by mixing a low bulk density graphite with a high bulk density graphite as the negative electrode active material, The energy density of the non-aqueous electrolyte secondary battery can be increased, and the battery characteristics can be improved.
[Brief description of the drawings]
[1] there is shown an embodiment of the present invention, is an enlarged view showing mixed bulk density high graphite particles C 1 and bulk low density of graphite particles C 2 graphite mixture.
FIG. 2, showing an embodiment of the present invention, is an assembled perspective view showing a configuration of a long cylindrical wound-type power generating element used for a large-sized non-aqueous electrolyte secondary battery.
[3] there is shown a conventional example is an enlarged view showing the graphite particles C 1 of a high bulk density graphite.
[4] there is shown a conventional example is an enlarged view showing a graphite particle C 2 low bulk density graphite.
[Explanation of symbols]
C 1 Graphite particles of graphite with high bulk density C 2 Graphite particles of graphite with low bulk density 12 Negative electrode 12a Copper foil 12b Negative electrode active material mixture

Claims (1)

かさ密度が０．５ｇ／ｃｃ以上の１種以上の黒鉛とかさ密度が０．２５ｇ／ｃｃ以下の１種以上の黒鉛とを混合し、かさ密度を０．４ｇ／ｃｃ以上とした黒鉛混合物を負極活物質の主成分とした合材を負極に担持させたことを特徴とする非水電解質二次電池の製造方法。A graphite mixture having a bulk density of 0.4 g / cc or more is obtained by mixing one or more graphites having a bulk density of 0.5 g / cc or more with one or more graphites having a bulk density of 0.25 g / cc or less. A method for producing a non-aqueous electrolyte secondary battery, wherein a mixture containing a main component of a negative electrode active material is supported on a negative electrode.
JP2002319998A 2002-11-01 2002-11-01 Manufacturing method of non-aqueous electrolyte secondary battery Pending JP2004158205A (en)

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US20100124707A1 (en) * 2008-11-14 2010-05-20 Sony Corporation Secondary battery and anode
US7767346B2 (en) 2005-10-17 2010-08-03 Samsung Sdi Co., Ltd. Anode active material, method of preparing the same, and anode and lithium battery containing the material
US8048339B2 (en) 2006-12-19 2011-11-01 Samsung Sdi Co., Ltd. Porous anode active material, method of preparing the same, and anode and lithium battery employing the same
WO2012164834A1 (en) * 2011-05-30 2012-12-06 株式会社豊田自動織機 Negative-electrode active material for lithium ion secondary cell, and negative electrode and secondary cell using negative-electrode active material for lithium ion secondary cell
US8709653B2 (en) 2004-03-08 2014-04-29 Samsung Sdi Co., Ltd. Negative active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery comprising the same
US8906557B2 (en) 2006-04-17 2014-12-09 Samsung Sdi Co., Ltd. Anode active material and method of preparing the same
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US9012082B2 (en) 2004-03-08 2015-04-21 Samsung Sdi Co., Ltd. Negative active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery comprising the same
US8709653B2 (en) 2004-03-08 2014-04-29 Samsung Sdi Co., Ltd. Negative active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery comprising the same
US7767346B2 (en) 2005-10-17 2010-08-03 Samsung Sdi Co., Ltd. Anode active material, method of preparing the same, and anode and lithium battery containing the material
US8906557B2 (en) 2006-04-17 2014-12-09 Samsung Sdi Co., Ltd. Anode active material and method of preparing the same
US8048339B2 (en) 2006-12-19 2011-11-01 Samsung Sdi Co., Ltd. Porous anode active material, method of preparing the same, and anode and lithium battery employing the same
US8562869B2 (en) 2006-12-19 2013-10-22 Samsung Sdi Co., Ltd. Porous anode active material, method of preparing the same, and anode and lithium battery employing the same
US9806333B2 (en) 2008-11-14 2017-10-31 Sony Corporation Secondary battery and anode
US9620810B2 (en) * 2008-11-14 2017-04-11 Sony Corporation Secondary battery and anode
US20100124707A1 (en) * 2008-11-14 2010-05-20 Sony Corporation Secondary battery and anode
JPWO2012164834A1 (en) * 2011-05-30 2015-02-23 株式会社豊田自動織機 Lithium ion secondary battery
CN103650217B (en) * 2011-05-30 2017-02-15 国立大学法人群马大学 Lithium ion secondary cell
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US9735422B2 (en) 2011-05-30 2017-08-15 National University Corporation Gunma University Lithium ion secondary cell
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