High-Performance Polycrystalline Ge Microwire Film Anodes for Li Ion Batteries

High-performance Li ion battery anodes have been made using Ge microwire films containing high levels of residual gallium (Ga). These materials were prepared by the electrochemical liquid–liquid–solid (ec-LLS) process with liquid metal alloy droplets containing Ga, indium (In), and copper (Cu) at T = 80 °C on Cu foil. The as-prepared Ge microwires yielded an initial discharge capacity of 1350 mA h g–1 and retained more than 80% of their original capacity after 80 cycles when subject to discharge–charge cycles at 0.1 C. Ge microwires where the residual metal content had been lowered still showed unusually large capacities and decent capacity retention, albeit less than those of the as-prepared materials. The cumulative data point to the premises that ec-LLS is amenable to making Ge microwires that are innately active as Li+ battery anodes and that Ga incorporation in Ge is beneficial to countering the material stress incurred during Li+ insertion.