Boosting aqueous zinc-ion storage in MoS2 via controllable phase

Recently, aqueous rechargeable Zn-ion batteries have attracted extensive attention, owing to their low-cost, high operational safety and environmental friendliness. However, the aqueous zinc-ion battery is still in a very infant stage, and the main challenge is to develop the ideal cathode due to the sluggish kinetics and low reversibility of divalent zinc ions. Herein, for the first time, we report controllable phase engineered few-layered MoS2 nanosheet as cathode materials for rechargeable aqueous Zn-ion batteries and systematically study their performance. We found that the obtained MoS2 with different phase contents showed distinct performance in the rechargeable aqueous zinc-ion battery. In particular, the MoS2 nanosheets with ~70% 1T phase content displays excellent specific capacity and shows outstanding long-term cyclic stability. The mechanisms involved were clarified by not only comprehensive characterizations, but also the density functional theory (DFT) simulations that reveal the 1T phase MoS2 has much lower Zn diffusion energy barriers. This study provides new insight into the effect of different phases on the performance of MoS2-based electrodes and will improve our understanding of developing better cathodes for the aqueous rechargeable Zn-ion batteries.