Graphene-decorated carbon-coated LiFePO4 nanospheres as a high-performance cathode material for lithium-ion batteries

Nanohybrids of graphene-decorated carbon-coated LiFePO4 nanospheres are prepared using a ball milling-assisted rheological phase method combined with a solid-state reaction. The hybrids are characterized by XRD, SEM, TEM, HRTEM, XPS, Raman and TGA, and their electrochemical properties are studied by CV, EIS and galvanostatic charge-discharge. The experimental results exhibit that multilayer graphene films are decorating carbon-coated LiFePO4 nanospheres without stacking, which results in an abundance of mesopores constituting a unique 3D “sheets-in-pellets” and “pellets-on-sheets” conducting network structure. This structure highlights the improvements of the rate and cyclic performance as a cathode material for lithium-ion batteries, because the highly conductive and plentiful mesopores promote electronic and ionic transport. As a result, the hybrids with approximately 3 wt% graphene exhibit an outstanding rate capability with an initial discharge capacity of 163.8 and 147.1 mA h g−1 at 0.1 C and 1 C, and the capacity is retained at 81.2 mA h g−1 even at 20 C. Moreover, the composites also reveal an excellent cycling stability with only an 8% capacity decay at 10 C after 500 cycles.