High capacity, reversible silicon thin-film anodes for lithium-ion batteries

The properties of amorphous 250 nm and 1 mum silicon films deposited by radio-frequency (rf) magnetron sputtering on copper foil are investigated using X-ray diffraction, scanning electron microscopy (SEM), and electrochemical methods. Galvanostatic half-cell electrochemical measurements conducted between 0.02 and 1.2 V using a lithium counter electrode have shown that the 250 nm Si thin films exhibit an excellent reversible specific capacity of nearly 3500 mAh/g when tested for 30 cycles. The high reversible capacity and excellent cyclability of the 250 nm sputtered silicon thin films suggest excellent adhesion between Si and Cu leading to high capacity retention. SEM analysis conducted on the 250 nm Si films after the 30th charge suggests the good adhesion of the similar to2 mum diam "plates" of silicon to the copper substrate. (C) 2003 The Electrochemical Society.