ELECTROLYTE HOLDER FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY

摘要

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 (3) 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 (3) is composed of an electrode group formed by winding a cathode (2) and an anode (1) or laminating the cathode (2) and the anode (1) one upon another with an electrolyte holder (3) serving as a separator interposed between the cathode (2) and the anode (1). 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 (1) 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 (2). 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 (1) is a carbon material.

主权项

1. An electrolyte holder for use in a lithium secondary battery in which an organic electrolytic solution is permeated or immersed into an electrode group formed by winding a cathode and an anode or by laminating said cathode and said anode one upon another with said electrolyte holder serving as a separator being interposed therebetween to repeatingly occlude and discharge lithium ions,
wherein said electrolyte holder consists of a multi-layer structure having at least two hydrophilic fibrous layers having different porosities; a porosity of said fibrous layer disposed at an interface between said fibrous layer and said anode is set smaller than that of said fibrous layer disposed at an interface between said fibrous layer and said cathode; and an average porosity of said entire fibrous layer is set to not less than 50%.