Mesoporous soft carbon as an anode material for sodium ion batteries with superior rate and cycling performance
Mesoporous soft carbon (MSC) was prepared from mesophase pitch using nano CaCO3 as the template. The crystalline structure of soft carbon consists of a disordered region with a large interlayer distance benefitting sodium ion insertion/extraction and a graphitic region with good electrical conductivity favoring high rate performance. Additionally, the mesoporous structure not only shortens the path of ion diffusion but also facilitates the penetration of non aqueous electrolytes, which can further enhance the electrochemical performance of MSC. Benefiting from its unique microstructure, the MSC delivers a reversible capacity of 331 mA h g 1 at 30 mA g 1, and retains a capacity of 103 mA h g 1 at 500 mA g 1 after 3000 cycles, indicating its excellent rate capability and cycling performance. Therefore, soft carbon with appropriate structure is expected to be another choice for anode materials of sodium ion batteries.