Janus Gel Electrolyte Enabled High-Performance Quasi-Solid-State Electrochromic Zn-Ion Batteries

Rechargeable electrochromic Zn-ion batteries (RZEBs) which combine electrochromic properties with energy storage capabilities, represent a promising development in the field of transparent batteries. The aqueous electrolytes are crucial for enhancing the kinetics and capacity of the cathode in RZEBs. However, the Zn anode suffers from hydrogen evolution reaction (HER), dendrite growth, and formation of byproducts due to excess water. Herein, we designed an integrated Janus gel electrolyte by incorporating a propylene carbonate-based organogel with a hydrogel electrolyte. The Janus gel electrolyte not only facilitates efficient Zn insertion in the cathode with short self-coloring time and good cyclic stability but also effectively mitigates water-induced corrosion in the Zn anode. Specifically, the Zn//Cu batteries exhibit a high Coulombic efficiency of 97.91%. Furthermore, the Zn//WO3 batteries exhibit a specific capacity of 43.64 mA h g-1 with a capacity retention of 60.84% after 160 cycles. This work provides an effective electrolyte design that significantly enhances the cycle stability of RZEBs.