Amorphous silicon film anode for lithium-ion battery

Amorphous silicon film with a thickness of up to 2 mu m was deposited on copper substrate by magnetron sputtering. The X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) results indicate that the sputtered film has an amorphous structure. Although its volume expansion after prolonged electrochemical lithiation and delithiation cycles was up to 300% as observed from the scanning electron microscopy (SEM) image, this anode is still with a good cyclic life. In the potential range 1.5 similar to 0.005 V (vs Li+/Li) at the current density of 0.1 mA(.)cm(-2), this film anode retains a capacity over 0.47 mAh(.)cm(-2) after 100 cycles, which is 84% of its initial capacity. The capacity fade ratio was only 0.16% per cycle. The HRTEM and SAED results show that the film still retains the amorphous structure after cycling, which is believed to be beneficial for the electrochemical cycle life.