| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery having high charge discharge cycle life characteristics and high capacity. <P>SOLUTION: An active material of silicon, tin or a compound containing silicon or tin is formed on a current collector 11 of a negative electrode in the form of a plurality of island regions so that the island regions are separated each other. Furthermore, a conductive protective film is formed on the current collector so as to cover the island regions. The conductive protective film is formed so as to also cover exposed regions (space portions) of the current collector on which the island regions 12 are not formed. Thus, expansion/contraction of the active material attendant on charge/discharge can be absorbed by the conductive protective film formed in the space portions between the island regions. Also, adhesiveness of the active material with the current collector can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT |
