Abstract
Rechargeable aqueous zinc-ion batteries (RZIBs) provide a promising complementarity to the existing lithium-ion batteries due to their low cost, non-toxicity and intrinsic safety. However, Zn anodes suffer from zinc dendrite growth and continuous unfavorable side reactions, resulting in low Coulombic efficiency (CE) and severe capacity decay. Here, we develop an ultrathin, fluorinated two-dimensional porous covalent organic framework (FCOF) film as a protective layer on the Zn surface to address these issues. The strong interaction between fluorine (F) in FCOF and Zn reduces the surface energy of the Zn (002) crystal plane and regulates planar growth of zinc anode materials. As a result, Zn deposits underneath FCOF films show parallel platelet morphology with (002) planar orientations preferred. Furthermore, F-containing nanochannels facilitate the de-solvation of hydrated Zn ions and prevent electrolyte penetration, thus retarding corrosion of Zn. Such unique FCOF films prolonged the Zn symmetric cell lifespan to over 1700 h, which is 13 times longer than the cells without protection (125 h). The assembled full cells demonstrate a cycle life of over 250 cycles at 3 mAcm-2 under practical conditions, including lean electrolyte (12 μLmAh-1), limited Zn excess (only 1×excess), and a high mass loading of MnO2 cathode (16 mgcm-2). This work provides a new perspective for the realization of planar deposition of zinc metal anodes for developing high performance Zn-based batteries.
Horizontally Arranged Zinc Platelet Electrodeposits Modulated by Fluorinated Covalent Organic Framework Film for High-Rate and Durable Aqueous Zinc Ion Batteries
