Pseudo-isotopic substituted (Co0.5Ni0.5)S2 anchoring on V4C3Tx MXene as an efficient anode for full sodium-ions batteries

Abstract

Materials used for conventional conversion-type anodes usually suffer from poor charge transfer and short lifespan, thereby limiting their utility in sodium-ion batteries (SIBs). To prevent these issues, the development of new anode materials is imperative. Herein, we used a synergistic modification strategy based on pseudo-isotopic substitution and 2D conductive skeleton support, to successfully prepare an unprecedented (Co0.5Ni0.5)S2@V4C3Tx with carbon layer coating (C@NCS@V4C3Tx) anode materials for SIBs. We noted that the C@NCS@V4C3Tx hybrid exhibited an ultrahigh reversible specific capacity of 705.6 mAh g−1 at 0.1 Ag−1, and the corresponding reversible capacity that is 100-times higher (10 A g−1) at a specific heat capacity of 347.6 mAh g−1, both higher than those of same kind batteries. Furthermore, the as-prepared hybrid also shows satisfactory long-term cycling stability, resulting from 2D skeleton V4C3Tx MXene with high conductivity and robustness. Through in-situ characterization techniques and density functional theory calculations, the sodium ions storage mechanism was well-investigated, specifically, the synergy effect between the high capacity of bimetallic TMS and metallic conductivity and excellent stability of V4C3Tx MXene plays an important role in high-performance achievement. Thus, assembled C@NCS@V4C3Tx//Na3V2(PO4)3 full-cell delivers outstanding electrochemical properties that can be useful as a portable integrated unit for self-powered systems.