Highly fluorinated non-aqueous solid-liquid hybrid interface realizes water impermeability for anti-calendar aging zinc metal batteries

Abstract

The thermodynamic instability of zinc metal in aqueous electrolytes is attributed to severe interfacial problems at the zinc anode. In this study, we designed and synthesized a porous-fluorinated covalent organic framework (FCOF) to encapsulate liquid perfluoropolyether (PFPE) and Zn(OTf)2 using a host-guest strategy to effectively solve the static corrosion problem of the anode. The highly fluorinate solid-liquid interface restricted free water from contacting zinc, thus greatly improving the anti-calendar aging of aqueous zinc-metal batteries. The highly fluorinated solid-liquid hybrid was constructed as a water impermeability and defect-free protection layer on the Zn surface (denoted as P-PFL@Zn). The P-PFL@Zn had integrated advantages: the liquid PFPE filled structural voids to eliminate interfacial defects, improve contact with Zn, and effectively adapt to the dynamic interface fluctuations. The solid FCOF promoted fast ion transport, provided confined space, and exhibited strong adsorption with the liquid phase, restricting the mobility of PFPE and facilitating the tight adherence of FCOF to the Zn surface. Due to the synergistic effect between the FCOF and PFPE, P-PFL@Zn exhibited a 40-day anti-calendar aging cycle, high Zn2+ transference number, ultrafast charging, and dendrite-free features. The assembled high mass-loading (20 mg cm−2) MnO2 cathode-based full cells exhibited good practical level performance under intermittent cycle mode (1000-cycle life with 90% capacity retention) and continuous cycle mode (1000-cycle life with limited Zn usage and high current density).