Electrochemical Performance of M2GeO4 (M = Co, Fe and Ni) as Anode Materials with High Capacity for Lithium-Ion Batteries

Abstract

M2GeO4 (M = Co, Fe and Ni) was synthesized as an anode material for lithium-ion batteries and its electrochemical characteristics were investigated. The Fe2GeO4 electrode exhibited an initial discharge capacity of 1127.8 mAh g(-1) and better capacity retention than Co2GeO4 and Ni2GeO4. A diffusion coefficient of lithium ion in the Fe2GeO4 electrode was measured to be 12.7 x 10(-8) cm(2) s(-1), which was higher than those of the other two electrodes. The electrochemical performance of the Fe2GeO4 electrode was improved by coating carbon onto the surface of Fe2GeO4 particles. The carbon-coated Fe2GeO4 electrode delivered a high initial discharge capacity of 1144.9 mAh g(-1) with good capacity retention. The enhanced cycling performance was mainly attributed to the carbon-coated layer that accommodates the volume change of the active materials and improves the electronic conductivity. Our results demonstrate that the carbon-coated Fe2GeO4 can be a promising anode material for achieving high energy density lithium-ion batteries.