A self-repairing polymer-inorganic composite coating to enable high-performance Zn anodes for zinc-ion batteries

There are some critical issues hindering the practical applications of aqueous zinc-ion batteries (ZIBs), although they possess high safety and low cost as one of promising energy storge devices, such as the Zn dendrite growth and the by-product of Zn4SO4(OH)6·xH2O (ZHS) resulted from some side reactions in a mild electrolyte. Herein, a compact and self-repairing solid electrolyte interface (SEI) film, as labeled the PVDF-Zn(TFSI)2-ZHS coating [The PVDF and Zn(TFSI)2 are polyvinylidene fluoride and zinc bis(trifluoromethanesulfonyl)imide, respectively], which turns the in-situ generated ZHS into a beneficial ingredient onto the pre-coated PVDF-based composite coating layer containing Zn(TFSI)2, was designed and fabricated by a simple doctor blade method. It is shown that the SEI layer can effectively isolate Zn from the electrolyte and homogenize the Zn2+ flux, and thus effectively suppress side reactions and dendrites growth. Benefiting from the hybrid SEI layer, a symmetric cell exhibits a high cycling stability over 750 h at 2.0 mA/cm2 and 2.0 mAh/cm2, and meanwhile, a full-cell, coupled with K+ pre-intercalation α-MnO2 (KMO) cathode, displays excellent rate performance, stable coulombic efficiency and an acceptable cycle life. This work provides a feasible approach for simple and scalable modification of Zn anodes to achieve high performance.