Induced Anionic Functional Group Orientation‐Assisted Stable Electrode‐Electrolyte Interphases for Highly Reversible Zinc Anodes

Abstract Dendrite growth and other side‐reaction problems of zinc anodes in aqueous zinc‐ion batteries heavily affect their cycling lifespan and Coulombic efficiency, which can be effectively alleviated by the application of polymer‐based functional protection layer on the anode. However, the utilization rate of functional groups is difficult to improve without destroying the polymer chain. Here, a simple and well‐established strategy is proposed by controlling the orientation of functional groups (─SO₃H) to assist the optimization of zinc anodes. Depending on the electrostatic effect, the surface‐enriched ─SO₃H groups increase the ionic conductivity and homogenize the Zn²⁺ flux while inhibiting anionic permeation. This approach avoids the destruction of the polymer backbone by over‐sulfonation and amplifies the effect of functional groups. Therefore, the modified sulfonated polyether ether ketone (H‐SPEEK) coating‐optimized zinc anode is capable of longtime stable zinc plating/stripping, and moreover an enhanced cycling steadiness under high current densities is also detected in a series of Zn batteries with different cathode materials, which achieved by the inclusion of H‐SPEEK coating without causing any harmful effects on the electrolyte and cathode. This work provides an easy and efficient approach to further optimize the plating/stripping of cations on metal electrodes, and sheds lights on the scale‐up of high‐performance aqueous zinc‐ion battery technology.