Highly stable GeO_x@C core-shell fibrous anodes for improved capacity in lithium-ion batteries

As a promising high capacity electrode material for lithium-ion batteries, germanium anodes are still to date restricted by the large volume change (>300%) during repeated cycling, which leads to a short cycle life and poor cycle stability in practical application. To overcome these challenges, herein a facile fabrication is reported to encapsulate GeO_x nanoparticles into hollow carbon shells using co-axial electrospinning. This core-shell structure has shown remarkable improvements in alleviating the volume change of GeO_x during cycling, minimizing the contact area between electrolyte and GeO_x to form a stable solid electrolyte interface film, and providing enhanced electrical conductivity. In addition, Ge nanoparticles in the GeO_x composite can promote the reversible capacity for the reversible utilization of Li₂O. As a result, such a GeO_x@C composite electrode exhibits excellent cycling ability with a reversible specific capacity of 875 mA h g^-1 at 160 mA g^-1 after 400 cycles, along with an improved rate capacity of 513 mA h g^-1 at a high current density of 1600 mA g^-1 upon 500 cycles.