Tailoring the Crystal‐Chemical States of Water Molecules in Sepiolite for Superior Coating Layers of Zn Metal Anodes

Abstract Protective coatings are effective in stabilizing Zn metal anodes. Nevertheless, the diverse features of the coating material increase the interface's complexity and often conceal the real mechanism of how the coating functions on electrode behavior. Moreover, the lack of precise regulation for a targeting feature results in ostensible correlations between structure and function, which sets great obstacles for further improving Zn anode performance. Herein, sepiolite, a hydrated mineral, and its derived materials to protect the Zn anode is introduced. By precisely tailoring different kinds of water molecules, the crystal/chemical states of the coating material is managed to regulate. Their impacts on Zn anode kinetics are revealed by experiments and DFT calculations, which indicate major interactions of Zn with the water molecules or the oxygens on the silicate backbone before/after the removal of zeolitic/coordinated water, and an important role of the structural water (Mg‐OH hydroxyl group) on the structural stability. The Sep‐OH sample with good stability and desired interaction with Zn shows the best performance in terms of uniforming Zn depositions, inhibiting side reactions and reducing polarizations. The tailoring of water molecules in mineral materials provides a new example for investigating and improving the Zn anodes and other similar electrodes.