Polycarbonyl polymer with zincophilic sites as protective coating for highly reversible zinc metal anodes

The Zn anode of aqueous zinc ion batteries (AZIBs) have suffered from a series of rampant side reactions such as dendrite growth and corrosion, which seriously affect the reversibility and stability of Zn anodes. Herein, a polycarbonyl polymer poly(1,4,5,8-naphthalene tetracarboxylic anhydride anthraquinone) imine (PNAQI) as the protective coating is synthesized through a simple solvothermal method with the raw materials of the equimolar 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and 2, 6-aminoanthraquinone (2,6-DAAQ). A series of characterizations such as contact angle measurement and ex-situ XRD analysis confirm that it can effectively prevent some side reactions. Moreover, CO on PNAQI can regulate the uniform distribution of zinc, thereby preventing the occurrence of zinc dendrites. Finally, the PNAQI@Zn//PNAQI@Zn symmetrical cell demonstrates a long cycle life exceeding 1000 h at current density of 1.0 mA cm^-2 and a capacity of 1.0 mAh cm^-2. The result significantly outperforms the cycling performance of the cell with bare zinc anode. Especially, the full battery of PNAQI@Zn//NH₄V₄O₁₀ demonstrates an excellent capacity retention and prolonged cycle life (96.9 mAh/g after 1000 cycles at 1.0 A/g) compared to Zn//NH₄V₄O₁₀. This work provides an effective, simple and low-cost solution for developing high-performance AZIBs.