A ZnO-halloysite coated composite separator capable of stabilizing zinc electrode interface for high-performance aqueous zinc-ion battery

In aqueous zinc-ion batteries, Zn dendrites growth, HER and by-product generation on the surface of Zn anode seriously affect the battery performance. To solve the problems, in this paper, a composite separator is prepared by coating the filter paper with halloysite and ZnO. The 3D network built by surface-negative halloysite provides a uniform nanoscale pore structure for the separator, which achieves uniform and efficient Zn 2+ transport. The –OH groups on the surface of halloysite promote the desolvation process of hydrated Zn 2+ by forming hydrogen bonds with H 2 O. The uniformly dispersed nanoscale ZnO in the coating promotes Zn 2+ transport, homogenizes Zn 2+ deposition on the surface of Zn anode by absorbing Zn 2+ , and reduces the nucleation overpotential (22.3 mV). Therefore, under the synergistic effect of halloysite and ZnO, the electrolyte/Zn anode interface is stabilized. The Zn-symmetric cell assembled with ZHLFP10 exhibits a long life of more than 1600 h at a current density of 0.2 mA cm −2 , while the Zn‖MnO 2 cell assembled with it exhibits a discharge-specific capacity of 131.0 mA h g −1 and a capacity retention rate of 80.35 % at a current density of 0.5 A g −1 for 1000 cycles.