Coordinating zincophilic sites and a solvation shell for a dendrite-free Zn anode under the synergistic effects of polyacrylonitrile and dimethyl sulfoxide

The advantages of aqueous zinc-ion batteries (AZIBs) are largely offset by the dendrite growth on the Zn anode, which is induced by the heterogeneous electrical field and limited ion transport of the Zn anode-electrolyte interface during plating and stripping. Here, we propose a dimethyl sulfoxide (DMSO)-H2O hybrid electrolyte containing polyacrylonitrile (PAN) additives (PAN-DMSO-H2O) to improve the electrical field and ion transport of the Zn anode, which can thus effectively inhibit dendrite growth. Experimental characterization and theoretical calculations show that PAN preferentially adsorbs on the Zn anode surface and provides abundant zincophilic sites after its solubilization by the DMSO, enabling a balanced electric field and lateral Zn plating. DMSO regulates the solvation structure of the Zn2+ ions and strongly bonds to H2O, which concurrently reduces side reactions and enhances the ion transport. Thanks to the synergistic effects of PAN and DMSO, the Zn anode presents a dendrite-free surface during plating/stripping. Moreover, Zn-Zn symmetric and Zn-NaV3O8·1.5H2O full batteries with this PAN-DMSO-H2O electrolyte achieve enhanced coulombic efficiency and cycling stability compared to those with a pristine aqueous electrolyte. The results reported herein will inspire other electrolyte designs for high-performance AZIBs.