Anode Properties of LaSi2/Si Composite Thick-Film Electrodes for Lithium Secondary Batteries

LaSi2 and LaSi2/Si composite as active materials for the negative electrode of lithium-ion battery were synthesized by mechanical alloying. Furthermore, thick-film electrodes prepared with a gas-deposition method by using these material powders, and their electrode performances were investigated. The LaSi2 GD-film electrode exhibited superb cycle stability, where more than 70 % of the initial capacity was maintained for a period of 1000 cycles, though the initial capacity was only about 40 mA h g-1. As for the LaSi2/Si composite electrodes, the original high discharge capacity of Si was retained even after several hundred cycles. The capacity after 300 cycles was 500 mA h g-1, which is larger than the theoretical capacity of graphite electrode practically used. Thus, we succeeded in developing the new composite electrode with both high discharge capacity of Si and good cyclability of LaSi2.