Sulphonated coal tar pitch as a carbon source to develop the storage capacity of Fe2O3@C materials

Utilizing metal oxides as substitutes for carbon anodes is imperative in advancing LIBs. Recently, the researchers regarding to the Fe2O3 have become very popular owing to its advantages such as a high theoretical capacity (1007 mAh g-1), cost-effectiveness and sustainability. In our present studies, the Fe2O3@SCTPC (Fe2O3 nanosphere coated by carbons which are obtained by the carbonizations using the sulphonated coal tar pitches) materials are firstly and successfully fabricated by a one-step hydrothermal method using the Fe(NO3)3·9H2O and sulphonated coal tar pitches (SCTPs). An intriguing observation is that the nanosphere Fe2O3 is encapsulated by carbons with a core-shell structure. This specific core-shell structure effectively mitigates the volume expansion of Fe2O3, and exhibits a notable enhancement in conductivity. Thanks to this unique structure, the Fe2O3@SCTPC electrode has a maximum capacity of 1106.74 mAh g-1 after 100 cycles at a current density of 0.1 A g-1 and a high reversible specific capacity of 373.5 mAh g-1 after 500 cycles at a current density of 2 A g-1, when it is used as an anode material for Li-ion battery. These results suggest that adjusting the structures of carbons is crucial to develop the potential storage capacity of the covered Fe2O3.