Ultra‐Efficient Synthesis of Nb4C3Tx MXene via H2O‐Assisted Supercritical Etching for Li‐Ion Battery

Abstract

AbstractNb4C3Tx MXene has shown extraordinary promise for various applications owing to its unique physicochemical properties. However, it can only be synthesized by the traditional HF‐based etching method, which uses large amounts of hazardous HF and requires a long etching time (> 96 h), thus limiting its practical application. Here, an ultra‐efficient and environmental‐friendly H2O‐assisted supercritical etching method is proposed for the preparation of Nb4C3Tx MXene. Benefiting from the synergetic effect between supercritical CO2 (SPC‐CO2) and subcritical H2O （SBC‐H2O）, the etching time for Nb4C3Tx MXene can be dramatically shortened to 1 h. The as‐synthesized Nb4C3Tx MXene possesses uniform accordion‐like morphology and large interlayer spacing. When used as anode for Li‐ion battery, the Nb4C3Tx MXene delivers a high reversible specific capacity of 430 mAh g−1 at 0.1 A g−1, which is among the highest values achieved in pure‐MXene‐based anodes. The superior lithium storage performance of the Nb4C3Tx MXene can be ascribed to its high conductivity, fast Li+ diffusion kinetics and good structural stability.