Nippon Kodoshi Corporation

Sei Corporation

Jyunichi Ushimoto

Shinji Saito

Takehiko Sawai

Kazunori Urao

Norihiro Wada

Masahiko Ueta

The present invention provides an electrolyte holder for a lithium secondary battery capable of holding an electrolytic solution inside electrodes or at an interface between the separator and each of the electrodes, preventing electrolyte shortage inside the electrodes, and restraining dendrite from precipitating and growing and also provide the lithium secondary battery, using the electrolyte holder, which is capable of achieving a cycle life to such an extent that the lithium secondary battery can be used for industrial application. An electrolyte holder () for use in the lithium secondary battery consists of a multi-layer structure having at least two hydrophilic fibrous layers (A, B) having different porosities. The electrolyte holder () is composed of an electrode group formed by winding a cathode () and an anode () or laminating the cathode () and the anode () one upon another with an electrolyte holder () serving as a separator interposed between the cathode () and the anode (). The organic electrolytic solution is permeated into the electrode group or the electrode group is immersed in the organic electrolytic solution. A porosity (40% to 80%) of the fibrous layer (A) disposed at an interface between the fibrous layer (A) and the anode () is set smaller than a porosity (60% to 90%) of the fibrous layer (B) disposed at an interface between the fibrous layer (B) and the cathode (). An average porosity of the entire fibrous layer is set to not less than 50%. The fibrous layers are formed by using cellulose fibers as a main material thereof. An active substance for use in the anode () is a carbon material.

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Kochi, Japan

Jyunichi Ushimoto