Heteroatom-doped fluoride interphase enables rapid ion conduction for highly stable zinc metal batteries

Abstract

Interlayer protection can effectively suppress zinc (Zn) dendrite growth, but suffers from sluggish Zn2+ conduction and anti-corrosion instability, which causes high polarization and inferior reversibility, hindering the practical applications of Zn metal batteries. Herein, we propose a heteroatom-dopant strategy for atomically-level regulation of fluoride interlayer to synchronously circumvent the above two issues. With a facile growth-doping approach, uniform phosphorus-doped ZnF2 (P-ZnF2) layer is grown on the surface of Zn foil. Experimental characterizations and computational analyses both demonstrate the doping of P atoms into ZnF2 lattice not only accelerates Zn2+ conduction across the interlayer, but also enhances the interlayer stability for durable protection. Consequently, the P-ZnF2 layer realizes a high reversibility with an average Coulombic efficiency of 99.5% and an impressive lifespan over 4200 h in symmetric cell. More encouragingly, the superior kinetics of stable P-ZnF2 achieves outstanding stability under rather demanding conditions: stable cycling over 4000 cycles at an ultrahigh current density of 50 mA cm–2; 320 h of lifespan with 91% of Zn utilization rate; 650 h of prolonged cycling behavior at a high temperature of 60 °C. Furthermore, the assembled full cell corroborates the practical feasibility of P-ZnF2 layer, even under an ultrahigh mass loading of cathode.