Nisshin Steel Co., Ltd.

Enax, Inc.

Norihiro Kon

Takeshi Shimizu

Takahiro Fujii

Yoshikazu Morita

Sho Majima

Yoshie Yoshida

Kazunori Ozawa

Norimasa Miura

Katsunari Norita

Takao Tsujimura

Takao Takasaki

Katsumi Kawai

Setsuko Koura

Manabu Katayose

Takashi Fujisaki

Yusuke Honma

A negative electrode collector using a copper-covered steel foil for carrying a negative electrode active material for lithium ion secondary batteries has a steel sheet as the core material thereof and has, on both surfaces thereof, a copper covering layer having a mean thickness tof from 0.02 to 5.0 &#x3bc;m on each surface, and of which the total mean thickness, t, including the copper covering layeris from 3 to 100 &#x3bc;m with t/t of at most 0.3. The steel sheet can be common steel, austenitic stainless steel, or ferritic stainless steel. The copper covering layer can be a copper electroplating layer (including one rolled after plating). On the surface of the copper covering layer, for example, a carbon-based active material layer that has been densified through strong roll pressing is formed, and the copper-covered steel foil and the carbon-based active material layer constitute the negative electrode collector.

Copper-covered steel foil, negative electrode, and battery

[Problem] To provide a negative electrode collector for lithium ion secondary batteries, having a high strength and a large discharge capacity. [Means for Resolution] A negative electrode collector using a copper-covered steel foilfor carrying a negative electrode active material for lithium ion secondary batteries, which has a steel sheetas the core material thereof and has, on both surfaces thereof, a copper covering layerhaving a mean thickness tof from 0.02 to 5.0 &#x3bc;m on each surface, and of which the total mean thickness, t, including the copper covering layeris from 3 to 100 &#x3bc;m with t/t of at most 0.3. To the steel sheet, for example, applicable is common steel, austenitic stainless steel or ferritic stainless steel. The copper covering layeris, for example, a copper electroplating layer (including one rolled after plating). On the surface of the copper covering layer, for example, a carbon-based active material layer that has been densified through strong roll pressing is formed, and the copper-covered steel foiland the carbon-based active material layer constitute the negative electrode collector.

Method of making negative electrode

There is provided a powder treating apparatus which can uniformly and successively combine and grow powders having different specific gravities or sizes together with a simple structure. The apparatus comprises a rotating containerinto which plural kinds of powders P having different specific gravities or sizes are supplied and which rotates in a predetermined direction, a fixed containerretaining the rotating container, primary treating means Mwhich is so arranged as to face an inner periphery surfaceS of the rotating containerand to extend in an axial direction, generates turbulence flow including eddying flow together with a rotational motion of the rotating container, and stirs and mixes the powders P having different specific gravities or sizes, a communicating holefor ejecting the powders P stirred and mixed by the primary treating means Mto a predetermined treatment space around the rotating container, and secondary treating means Mwhich applies planar compressive shear force to the powders P ejected from the communicating holewith an inner periphery surfaceS of the fixed containerto carry out a composite treatment, and causes the powders P having undergone a composite treatment to flow back in the rotating container.

Powder treating apparatus

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Yamagata, Japan

Norihiro Kon