NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND ITS CHARGING METHOD

摘要

PROBLEM TO BE SOLVED: To enhance discharge capacity and energy density by providing a Li ion conductive porous high polymer electrolyte in a negative electrode mix layer containing a carbon material and having a specific porosity and by including Li in the pores of the electrolyte in a charged state. SOLUTION: The porosity of a negative electrode mix layer is set to 10-50%. Thereby, the safety and the cycle characteristic of this battery are improved. The safety is further improved by setting the volume ratio of a Li ion conductive porous high polymer electrolyte within the pore parts of the negative electrode mix layer to 0.01-0.6. The weight of a positive electrode active material and the weight of a carbon material of a negative electrode are preferably determined so as to satisfy the following relationship: (the reversible capacity of the positive electrode)/(the reversible capacity of the negative electrode + the irreversible capacity of the negative electrode)>1. Thereby, Li is deposited on the negative electrode so that high capacity and high energy density can be accomplished. At that time, the electrically deposited Li is received in the pores inside the negative electrode mix layer.