Pre‐Intercalation of TMA Cations in MoS2 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 MoS2 interlayers to expand its spacing from 0.63 to 1.06 nm. The pre‐intercalation of TMA+ induces phase transition of MoS2 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 Zn2+ and MoS2 layers. Consequently, two orders magnitude high Zn2+ ions diffusion coefficient and 11 times enhancement in specific capacity (212.4 vs 18.9 mAh g‒1 at 0.1 A g‒1) are achieved. The electrochemical investigations reveal both Zn2+ and H+ can be reversibly co‐inserted into the MoS2‐TMA electrode. Moreover, the steady habitat of TMA+ between MoS2 interlayers affords the MoS2‐TMA with remarkable cycling stability (90.1% capacity retention after 2000 cycles at 5.0 A g‒1). These performances are superior to most of the recent zinc ion batteries assembled with MoS2 or VS2‐based cathodes. This work offers a new avenue to tuning the structure of MoS2 for aqueous ZIBs. Pre‐intercalation of tetramethylammonium (TMA+) into MoS2 can not only expand the interlayer spacing to 1.06 nm, but also induce phase transition of 2H‐ to 1T‐MoS2. Besides, DFT calculation demonstrates that TMA+ can effectively shield the interactions between Zn2+ and MoS2 layers, leading to two orders magnitude high Zn2+ ions diffusion coefficient and 11 times enhancement in specific capacity.