Advanced performance of S and N co-doped Sb@CNFs with a 3D conductive network as superior lithium-ion battery anodes

Antimony-based anodes possessing advantages of stable operating voltage and high theoretical capacity can replace graphene as alloy-based electrodes material in LIBs applications. However, the problems of capacity decaying and poor stability of Sb-based materials due to volume expansion and structural crushing during the long-term cycling remain to be solved. Therefore, we propose a strategy of using S and N co-doped carbon nanofibers encapsulated with Sb nanoparticles to overcome the above problems. The proposed material exhibits an excellent lithium storage performance with a high reversible specific capacity of 734 mAh g −1 at 0.1 A g −1 after 50 cycles (474.8 mAh g −1 at 1 A g −1 after 800 cycles, 394.5 mAh g −1 at 2 A g −1 after 2000 cycles). Importantly, a specific capacity of 288.5 mAh g −1 remains after more than 5000 cycles. The superior electrochemical performance of the S and N co-doped electrode is attributed to the proven structure and stability of the carbon matrix alleviating the volume changes of Sb during the process of lithium intercalation and extraction. The alloying/de-alloying reactions of the S@Sb@N-CNFs composite in the first charging/discharging process were systematically investigated by ex-situ XRD . This strategy of S and N co-doped carbon matrix could establish Sb-based materials as potential high-performance anodes for LIBs.