A Gradient Solid-like Electrolyte Stabilizing Zn Anodes by In Situ Formation of a ZnSe Interphase

Rechargeable aqueous Zn-ion batteries are renowned for their safety, cost-effectiveness, environmental friendliness, and high capacity. However, critical issues, such as restricted electrode kinetics and uncontrolled dendrite growth of Zn anodes, have hindered their practical applications. Here, we propose a gradient solid-like electrolyte (GSLE) to enhance the overall performance of Zn anodes and Zn-ion batteries. It shows a high room-temperature conductivity of 13.3 mS cm^-1 with an enhanced Zn²⁺ transference number of 0.67. With its negatively charged network, the GSLE establishes a Zn²⁺-rich region at the Zn|electrolyte interface, thereby boosting the interfacial charge transfer and accelerating electrode kinetics. Moreover, the GSLE in situ establishes a ZnSe-containing interphase on the surface of Zn anodes during cycling. Such an interphase effectively guides uniform Zn deposition and inhibits side reactions. As a result, symmetric cells using the GSLE demonstrate stabilized Zn plating/stripping cycling over 1400 h and tolerate a high critical current of 15 mA cm^-2. Furthermore, the assembled vanadium-based full cells deliver a remarkable capacity of 125.4 mAh g^-1 at 4 A g^-1 and achieve a 90% capacity retention after 1000 cycles.