Sulfur-doped graphene-decorated Li2FeSiO4@C nanocomposite: A novel cathode material for lithium energy storage

Li₂FeSiO₄ has been regarded as a highly advanced cathode material for lithium energy storage because of its high theoretical capacity, good chemical stability and low cost. However, the low Li⁺ diffusion coefficient and poor electrical conductivity of pure Li₂FeSiO₄ result in bad rate capability and cyclic property. To address these problems, the designed sulfur-doped graphene-promoted Li₂FeSiO₄@C (abbreviated as SG-LFS@C) nanocomposite has been fabricated by a simple sol-gel technology and high-temperature solid-state reaction. Electrochemical tests demonstrate that the resulted SG-LFS@C displays superior lithium storage properties than Li₂FeSiO₄@C (abbreviated as LFS@C). The initial discharge capacities of SG-LFS@C were 260.7 and 139.1 mAh g⁻¹ at 0.1 and 10C, respectively. Even after 400 cycles at 20C, the specific capacity of SG-LFS@C can still reach 116.5 mAh g⁻¹ with the capacity retention rate of 94.9 %. The superior lithium storage performances for SG-LFS@C cathode are mainly attributed to the designed conductive nanostructures and the formed nanosized Li₂FeSiO₄ particles. Thus, this novel concept provides a new direction for further research on other lithium-ion batteries cathode materials.