Low volume expansion hierarchical porous sulfur-doped Fe2O3@C with high-rate capability for superior lithium storage

Ingenious morphology design and doping engineering have remarkable effects on enhancing conductivity and reducing volume expansion, which need to be improved by transition metal oxides serving as anode materials for lithium-ion batteries. Herein, S-0.15-Fe2O3@C nano-spindles with a hierarchical porous structure are obtained by carbonizing MIL-88B@PDA and subsequent high-temperature S-doping. Kinetic analysis showed that S-doping increases capacitive contribution, enhances charge transfer capability and accelerates Li+ diffusion rate. Therefore, the S-0.15-Fe2O3@C electrode exhibits superior lithium storage performance with a remarkable specific capacity of 1014.4 mA h g(-1) at 200 mA g(-1), ultrahigh rate capability of 513.1 mA h g(-1) at 5.0 A g(-1), and excellent cycling stability of 842.3 mA h g(-1) at 1.0 A g(-1) after 500 cycles. Moreover, the size of S-0.15-Fe2O3@C particles barely changed after 50 cycles, indicating an extremely low volume expansion, related to the carbon shell, fine Fe2O3 nanoparticles, abundant voids inside, and improved kinetics. This strategy can be applied to other metal oxides for synthesizing anodes with high-rate capability and low volume expansion.

Automated summary

Ingenious morphology design and doping engineering significantly enhance the conductivity and reduce the volume expansion of transition metal oxides as anode materials for lithium-ion batteries. In this study, S-0.15-Fe2O3@C nano-spindles with a hierarchical porous structure were synthesized through carbonization and S-doping. The S-doping increases capacitive contribution, charge transfer capability, and Li+ diffusion rate, leading to the superior lithium storage performance of the S-0.15-Fe2O3@C electrode with high specific capacity, ultrahigh rate capability, and excellent cycling stability. The strategy can be extended to other metal oxides for high-rate capability and low volume expansion anodes.