In situ synthesis of SnPS3/Ti3C2Tx hybrid anode via molten salt etching method for superior sodium-ion batteries

Abstract

Recently, SnPS₃ has gained attention as an impressive sodium-ion battery anode material because of its significant theoretical specific capacity derived from the conversion-alloying reaction mechanism. Nevertheless, its practical applicability is restricted by insufficient rate ability, and severe capacity loss due to inadequate electrical conductivity and dramatic volume expansion. Inspired by the electrochemical enhancement effect of MXene substrates and the innovative Lewis acidic etching for MXene preparation, SnPS₃/Ti₃C₂T_x MXene (T = Cl and O) is constructed by synchronously phospho-sulfurizing Sn/Ti₃C₂T_x precursor. Benefiting from the boosted Na⁺ diffusion and electron transfer rates, as well as the mitigated stress expansion, the synthesized SnPS₃/Ti₃C₂T_x composite demonstrates enhanced rate capability (647 mA h g⁻¹ at 10 A g⁻¹) alongside satisfactory long-term cycling stability (capacity retention of 94.6% after 2000 cycles at 5 A g⁻¹). Importantly, the assembled sodium-ion full cell delivers an impressive capacity retention of 97.7% after undergoing 1500 cycles at 2 A g⁻¹. Moreover, the sodium storage mechanism of the SnPS₃/Ti₃C₂T_x electrode is elucidated through in-situ and ex-situ characterizations. This work proposes a novel approach to ameliorate the energy storage performance of thiophosphites by facile in-situ construction of composites with MXene.