A binary eutectic electrolyte design for high-temperature interface-compatible Zn-ion batteries

The deterioration of aqueous zinc-ion batteries (AZIBs) is confronted with challenges such as unregulated Zn2+ diffusion, dendrite growth and severe decay in battery performance under harsh environments. Here, a design concept of eutectic electrolyte is presented by mixing long chain polymer molecules, polyethylene glycol dimethyl ether (PEGDME), with H2O based on zinc trifluoromethyl sulfonate (Zn(OTf)2), to reconstruct the Zn2+ solvated structure and in situ modified the adsorption layer on Zn electrode surface. Molecular dynamics simulations (MD), density functional theory (DFT) calculations were combined with experiment to prove that the long-chain polymer-PEGDME could effectively reduce side reactions, change the solvation structure of the electrolyte and priority absorbed on Zn(002), achieving a stable dendrite-free Zn anode. Due to the comprehensive regulation of solvation structure and zinc deposition by PEGDME, it can stably cycle for over 3200 h at room temperature at 0.5 mA/cm2 and 0.5 mAh/cm2. Even at high-temperature environments of 60 degrees C, it can steadily work for more than 800 cycles (1600 h). Improved cyclic stability and rate performance of aqueous Zn||VO2 batteries in modified electrolyte were also achieved at both room and high temperatures. Beyond that, the demonstration of stable and high-capacity Zn||VO2 pouch cells also implies its practical application. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.