High-capacity, microporous Cu₆Sn₅-Sn anodes for li-ion batteries

Three-dimensional, microporous Cu₆Sn₅-Sn architectures were created by electrodeposition of copper and tin onto sintered copper foam substrates and evaluated as anodes for lithium-ion batteries. The electrodes were characterized before and after cycling by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectrometry. Before cycling, the electrochemically deposited films consisted of a combination of crystalline Cu₆Sn₅ and Sn, whereas after cycling, the films appeared amorphous to X-rays. When evaluated in coin cells against metallic lithium, the composite Cu₆Sn₅-Sn electrodes delivered a reversible capacity of 670 mAhg, which is significantly greater than the capacity achieved previously from powdered (ballmilled) and thin-film (sputtered) Cu6 Sn5 electrodes, typically 200-350 mAhg.