Structural engineering of tin sulfides anchored on nitrogen/phosphorus dual-doped carbon nanofibres in sodium/potassium-ion batteries

Abstract

Na/K-ion batteries (SIBs/PIBs) owing to their low cost, earth abundance, appropriate redox potential and comparable electrochemical performance, have gained ever-growing attention. Nevertheless, it remains a major challenge for high performance of SIBs/PIBs applications. Herein, with the assistance of waste chlorella as the reactor and phosphorous source, we designed few-layered tin sulfides immobilized on nitrogen and phosphorus dual-doped carbon nanofibres (SnSx-N/P-CNFs). The characterization and DFT calculation results demonstrate that N/P co-doping is expected to favour the distribution of electron density and strengthen ion reaction kinetics, which can enhance the Na+/K+ storage performance. As expected, as an anode material for SIBs, the SnSx-N/P–CNF electrode displays an impressive capacity (522 mAh g−1 after 50 cycles at 0.1 A g−1) and promising long-life cycling performance (214 mAh g−1 up to 32,000 cycles at 10 A g−1). Moreover, it also exhibits exceedingly impressive potassium-ion storage performance (468 mAh g−1 at 0.1 A g−1 after 100 cycles and 170 mAh g−1 exceed 10,000 cycles at 5 A g−1), which is the one of the optimal long-cycle properties reported for Sn-based anode for PIBs to date. Our work provides a reference for using biomass algae as the nitrogen and phosphorous source in constructing energy storage materials.