Fluorine-doped and carbon-coated porous SnO2-NiO composite as a high performance anode material for lithium ion batteries

A novel fluorine-doped porous SnO2-NiO@C-F (SNCF) composite anode material was synthesized by NaCl template method through high-energy ball milling and calcination under nitrogen atmosphere. This pore-like structure promotes electrolyte penetration as well as provides good intergranular electrical contact, which shortens the Li+ transport distance of electrons and F doping enhances the loading of SnO2-NiO particles on the surface of carbon materials and enhances electron transport and Li+ diffusion in the composite. In addition, NiO with relatively small content and distribution along the carbon substrate can improve the irreversible decomposition process of Li2O due to the catalytic properties of Ni-based oxides. The encapsulated carbon can buffer the volume expansion and avoid the accumulation of active materials, thus improving the material properties. Hence, the porous SnO2-NiO@C-F composite has a large capacity of 989.2 mAh g-1 after 150 cycles at 0.2 A g-1, as well as a long-time cycling stability that still shows a capacity of 768.9 mAh g-1 after 1000 cycles at 1 A g-1. In addition, it has excellent rate property, reaching a capacity of 389.0 mAh g-1 even at 5 A g-1. Therefore, the porous SnO2-NiO@C-F is a prospering anode material for lithium ion batteries (LIBs).