A High-Performance Aqueous Zinc-Thiocyanogen-Iodine Battery with High Capacity and Dual Platforms

Aqueous zinc-iodine batteries (AZIBs) have emerged as promising energy storage devices owing to their advantages of low cost, inherent safety and environmental friendliness. However, most AZIBs primarily operate through a single $\mathrm{I}^{0}/\mathrm{I}^{-}$ redox reaction, which results in constrained operating voltage and capacity. Recently, the four-electron conversion mechanism of $\mathrm{I}^{+}/\mathrm{I}^{0}/\mathrm{I}^{-}$ has been activated to solve these issues, yet this process encounters challenges such as intricate cross side reactions. Herein, high-capacity and dual-platform Zn-(SCN)2-12 batteries (ZSIBs) have been prepared by introducing a water-in-salt (WIS) electrolyte system with $\text{I-}$ and $\text{SCN}^{-}$. The introduction of $\mathrm{V}_{2}\text{CT}_{\mathrm{x}}$ MXene effectively inhibited the side-reaction and shuttle effects present in ZSIBs, demonstrated a discharge specific capacity of 806.4 $\mu \text{Ahcm}^{-2}(290\text{mAhg}^{-1})$, the device can retain 97.84% in 500 charge/discharge cycles. Additionally, the combination of oxygen-enriched carbon(ACC) and $\mathrm{V}_{2}\text{CT}_{\mathrm{x}}$ MXene enabling a high discharge specific capacity of 2995.8 $\mu \text{Ahcm}^{-2}$ and energy density of 3.60 $\text{mWhcm}^{-2}$, thereby shedding new light on the design and development of aqueous Zn-ion batteries.