Zinc metal free polymer-based anode materials for ultralong aqueous zinc-ion rechargeable battery

Abstract

Aqueous Zn-ion batteries (AZIBs) have garnered significant attention for grid-level energy storage systems owing to their high safety, cost-effectiveness and environmental friendliness. However, the practical application of the AZIBs always suffers from uncontrollable Zn dendrite growth, low coulombic efficiency and the irreversible kinetics of electrodes. Herein, we propose a highly zincophilic organic polyimide-decorated graphene (PI/G) anode synthesized through straightforward polycondensation reactions featuring an optimized electronic structure with a π-conjugated network. The well-organized, high-density diimide groups in PI/G material offer more accessible electrochemically active sites and reduce the energy barrier for ion diffusion as supported by electrochemical, ex-situ characterizations and density functional theory (DFT) simulations. The synthesized PI/G anode provides a low redox potential, high specific capacity and fast rate capability. When a full AZIB is fabricated by the pairing of polymer anode with ZnMn₂O₄ cathode, the resulting dendrite-free device provides a remarkable specific capacity and ultra-long cycle stability, retaining 84 % of its capacity at 10 A g⁻¹ even after 50,000 cycles. This stability is achieved through a reversible Zn²⁺ co-participative phase transfer mechanism at redox-active sites. This study hopes to pave the way for an alternative design and development strategy for practical AZIB applications in large-scale grid energy storage systems.