Improved cycle performance of annealed Si/Ni/Cu film electrodes

Electrochemical properties of Si/Ni/Cu film electrodes were investigated with different Ni film thicknesses (50-600 nm) and annealing temperatures (200-500 0C). The morphology of amorphous Si film was considerably affected by surface features of the Ni under-layer. The best cycle performance of 90.2% retention after 70 cycles was obtained from Si/Ni/Cu film with 300 nm thick Ni film and after 400 0C annealing. For the annealed Si/Ni/Cu electrode, the surface morphology (protrusions) and the formation of compounds among Si, Ni and Cu prohibited the volume expansion of Si during the charge-discharge process and enhanced adhesion between films and substrate, respectively.