| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which is excellent in charge/discharge cycle characteristics, and high in weight energy density by applying an active material having the different variation amount of expansion and contraction in a charge/discharge process on both surface of a negative current collector. SOLUTION: A positive electrode and a negative electrode formed by applying an active material capable of inserting/releasing lithium ions on the both surfaces of a two dimensional current collector are stacked through a separator, a plurality of stacks are housed in an aluminum battery container, and a nonaqueous electrolyte containing lithium ions is injected to obtain a lithium ion secondary battery. An active material 4 mainly comprising graphite for example having the large variation amount of expansion and contraction in a charge/ discharge process is applied on one surface of a negative current collector 5, and an active material 4' mainly comprising amorphous carbon for example having the small variation amount is applied on the other surface. An active material 1 which expands in a charge process and extracts in a discharge process, such as LixCoO2 (0<=x<=1) is applied on the surface on a positive current collector 2 facing the negative active material 4' and an active material 1' which expands in the discharge process and contracts in the charge process, such as Liy Mn2 O4 is arranged on the surface of the positive current collector 2 facing the negative active material 4. |
