As shown in FIG. 1, in a vicinity of a peripheral edge of the wound electrode group 1, a negative electrode terminal 6 is connected to the negative electrode current collector 3a of the negative electrode 3 of an outermost layer, and a positive electrode terminal 7 is connected to the positive electrode current collector 5a of the positive electrode 5 at the inside. The negative electrode terminal 6 and the positive electrode terminal 7 are extended outwardly from an opening of the bag-shaped case 2. For example, the liquid nonaqueous electrolyte is injected into the opening of the bag-shaped case 2. The wound electrode group 1 and the liquid nonaqueous electrolyte can be sealed by heat-sealing the opening of the bag-shaped case 2 across the negative electrode terminal 6 and the positive electrode terminal 7.

The negative electrode terminal is formed from a material which is electrically stable in Li absorption-release potential of the negative electrode active material and has conductivity. Specific examples thereof include copper, nickel, stainless steel, aluminium, and an aluminium alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. It is preferable that the negative electrode terminal is formed from the same material as that of the negative electrode current collector in order to reduce the contact resistance with the negative electrode current collector.