Pre-Intercalation of TMA Cations in MoS Interlayers for Fast and Stable Zinc Ion Storage.

Applications of aqueous zinc ion batteries (ZIBs) for grid-scale energy storage are hindered by the lacking of stable cathodes with large capacity and fast redox kinetics. Herein, the intercalation of tetramethylammonium (TMA) cations is reported into MoS interlayers to expand its spacing from 0.63 to 1.06 nm. The pre-intercalation of TMA induces phase transition of MoS from 2H to 1T phase, contributing to an enhanced conductivity and better wettability. Besides, The calculation from density functional theory indicates that those TMA can effectively shield the interactions between Zn and MoS layers. Consequently, two orders magnitude high Zn ions diffusion coefficient and 11 times enhancement in specific capacity (212.4 vs 18.9 mAh g at 0.1 A g) are achieved. The electrochemical investigations reveal both Zn and H can be reversibly co-inserted into the MoS-TMA electrode. Moreover, the steady habitat of TMA between MoS interlayers affords the MoS-TMA with remarkable cycling stability (90.1% capacity retention after 2000 cycles at 5.0 A g). These performances are superior to most of the recent zinc ion batteries assembled with MoS or VS-based cathodes. This work offers a new avenue to tuning the structure of MoS for aqueous ZIBs.