| 摘要 |
PURPOSE: To increase charging/discharging capacity by limiting the thickness of a positive electrode active material on one side within a specified range. CONSTITUTION: In a lithium secondary battery using lithium nickel oxide in positive electrode 1, thin electrodes a current collector in between are used, and the thickness of an active material of the positive electrode 1 on one side is limited to 30-70μm to increase load performance and charging/discharging capacity. When lithium nickel oxide is used as the positive electrode active material, since the diffusion coefficient of lithium in the solid of the lithium nickel oxide is small, a load characteristic is not so good compared with other lithium transition metal oxides. Therefore, the thickness of the positive electrode active material is optimized to increase the diffusion coefficient and to improve the load characteristic. When the thickness of the active material is more than 70μm, the active material is not utilized to its deep part, and the capacity becomes low. When the thickness is less than 30μm, part not contributing to charging/discharging such as aluminum foil and a separator 3 is increased, and the capacity becomes low. Therefore, the thickness of the active material is limited to 30-70μm. |
