Impact of Ge content on the electrochemical performance of Germanium Oxide/Germanium/ reduced graphene (GeO2/Ge/r-GO) hybrid composite anodes for lithium-ion batteries

Abstract

Hybrid composites between Germanium (Ge) and carbonaceous materials have been extensively studied due to the carbonaceous’ component’s ability to mitigate the intrinsic problems pertaining to Ge-based anodes. The mitigation of reduced cycling ability and rate capability allows for the unhindered benefit of higher capacities in Ge-carbonaceous composite anodes. Here, the effect of different Ge mass loading on electrochemical performance is studied on a GeO2/Ge/r-GO composite made using controlled microwave radiation of ball-milled Ge and sonicated dispersion of graphene Oxide (GO) as a lithium battery anode. The composite anode at Ge 25% showed greatest cycling retention with 91% after 100 cycles and an average specific capacity of 300 mAh/g (1600 mAh/g Ge). At 75% Ge mass loading the anode suffered with limited cycling retention of 57.5% at the cost of greater specific capacities. The composite at 50% Ge attained advantageous characteristics of both composites with a stable cycling performance of 71.4% after 50 cycles and an average specific capacity of 400 mAh/g (1067 mAh/g Ge, all conducted at a current density of 100 mA/g). A positive linear correlation is revealed for increasing Ge mass loadings and specific capacities in Ge-carbonaceous as anode materials.