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 electrolyte corrosion, resulting in poor reversibility. Here, we develop an ultrathin, fluorinated two-dimensional porous covalent organic framework (FCOF) film as a protective layer on the Zn surface. The strong interaction between fluorine (F) in FCOF and Zn reduces the surface energy of the Zn (002) crystal plane, enabling the preferred growth of (002) planes during the electrodeposition process. As a result, Zn deposits show horizontally arranged platelet morphology with (002) orientations preferred. Furthermore, F-containing nanochannels facilitate ion transport and prevent electrolyte penetration for improving corrosion resistance. The FCOF@Zn symmetric cells achieve stability for over 750 h at an ultrahigh current density of 40 mA cm−2. The high-areal-capacity full cells demonstrate hundreds of cycles under high Zn utilization conditions.
Highlights
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
The growth mechanism of fluorinated two-dimensional porous covalent organic framework (FCOF) film during solvothermal processes is mainly attributed to the fusion of numerous nanospheres that are formed during a co-condensation reaction (Supplementary Fig. 2), as revealed by the time-dependent morphology evolution (Supplementary Fig. 4)
The excellent electrochemical performance of the FCOF@Zn anodes can be mainly attributed to the planar deposition morphology, i.e., the predominantly parallel tessellated Zn platelets
Summary
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. Zn anodes suffer from zinc dendrite growth and electrolyte corrosion, resulting in poor reversibility. The strong interaction between fluorine (F) in FCOF and Zn reduces the surface energy of the Zn (002) crystal plane, enabling the preferred growth of (002) planes during the electrodeposition process. The polyethylene-glycolin electrolytes[25] make the Zn deposits show a preferred orientation exposure of (002) and (103) planes, which mitigates dendrite formation and reduces the later corrosion rates. Substrate such as stainless steel modified with an aligned graphene layer[5], shows good lattice matching with Zn, which induces epitaxial deposition of Zn along the (002) planes, achieving ultra-long cycling life. The surface stability of inorganic crystals has long been thought to be dominated by their surface energy[31,32,33]
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