Controllable Etching of Ti3SiC2 to Produce Fluorine‐Enriched, Hydrophobic 2D Titanium Carbide for Ultrastable Zinc Ion Batteries

Abstract

AbstractMXenes are mainly produced via selectively etching MAX phases in aqueous F‐containing solutions, commonly showing a highly hydrophilic character due to their plentiful ‐O and ‐OH terminations. However, the hydrophilic nature of MXenes may deteriorate their durability and stability as employed in humid and aqueous environments. Here, this work demonstrates a new etching approach to produce fluorine‐enriched MXene Ti3C2Fx via selective etching of Si from Ti3SiC2 in sulfur hexafluoride (SF6) gas. During the etching process, SF6 enables the selective removal of Si species with the formation of volatile SiF4 and efficiently reacts with the exposed surface of Ti3C2 slabs, affording Ti3C2Fx MXene with a fraction of ‐F termination up to 87 at.% and good hydrophobicity. Such hydrophobic Ti3C2Fx MXene is beneficial to suppress water‐induced side reactions and decrease the Zn nucleation energy barrier, delivering a long cyclic lifespan of 1200 h and superior rate performance up to 6.4 mA cm−2 in Ti3C2Fx/Zn symmetric cells. Coupled with nickel hexacyanoferrate (NiHCF) as a cathode, the zinc full cell with Ti3C2Fx/Zn anode exhibits good rate capabilities (58 mAh g−1, 3.2 A g−1) and long cycling stability up to 1000 cycles at 3.2 A g−1.