High‐Performance Zinc‐Ion Battery Enabled by Tuning the Terminal Group and Chain Length of PEO‐based Oligomers

Abstract Side reactions and dendrite growth issues originated from free water seriously hamper the application of zinc‐ion batteries (ZIB). The electrolyte strategy of using a co‐solvent system has been proven to effectively improve the performance of ZIB. However, lack of thorough understanding of the co‐solvent structure on the performance of electrolytes hinders the rational design of co‐solvent electrolytes. Here, by studying how the terminal group and chain length of polyethylene oxide (PEO) based oligomers affect the electrochemical performance of ZIB, we obtained the optimized PEO oligomer structure and the underlying mechanism. As a result, the designed co‐solvent electrolyte enables the Zn|| NH 4 V 4 O 10 full cell to gain a 98.5 % capacity retention over 9500 cycles at 10 A g −1 . This work provides new insights into the inhibition of water‐related side reactions and further promote the development of electrolytes for ZIB and other metal batteries.