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.

© 2023  Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.