Copper-Coated Amorphous Silicon Particles as an Anode Material for Lithium-Ion Batteries

Colloidally grown hydrogenated amorphous silicon (a-Si:H) particles offer promise as anodes for lithium ion batteries with a much higher energy density than graphite. We have found that significantly improved battery cycle performance and enhanced lithium storage capacity (by a factor of 7) is achieved by depositing copper (Cu) on the a-Si:H particles using a polyol reduction method. The superior performance appears to result from an electronically conducting network formed by the Cu coating. High-resolution interfacial spectroelectrochemical studies with in situ Raman spectroscopy illustrates the role of Cu coating over a-Si:H particles and provides insight into improving low Coulombic efficiency and capacity fading on cycling of Si-based anodes in Li-ion batteries.