A biomimetic polymer-clay nanocomposite coating for dendrite-free Zn metal anode

Dendrite growth and side reactions in Zn metal aqueous batteries have limited their practical application. Herein, based on the poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) codoped with poly(ethylene oxide) (PEO) and Zn-based montmorillonite (Zn-MMT), a biomimetic ant nest porous polymer-clay composite as a protective layer is fabricated on the surface of Zn anode (PC@Zn). The PC coating demonstrates flexibility, high mechanical robustness and high ionic conductivity, simultaneously, which can accommodate the Zn surface volume change and maintain close contact with the Zn anode during the cycling. Furthermore, the PC@Zn with improved hydrophilicity can effectively suppress both Zn dendrites growth and H2 evolution by regulating the homogeneous ion diffusion and uniform Zn deposition. Therefore, the PC@Zn anode presents an ultralong cycle lifespan and reversible Zn stripping/plating for thousands of hours at 0.25, 1, and 5 mA cm-2 with high Coulombic efficiency. A full cell PC@Zn//MgVO demonstrates a high capacity (146.2 mAhg-1) at 5 A g-1 and high capacity retention of 95.5% after 3000 cycles. Based on the concept of biomimetics, this work gives inspiration for designing artificial coating layers for ultrastable dendrite-free aqueous metal batteries.