Novel Anchored Branched Polymer Coating Layers for Enhanced Redox Kinetics in Aqueous Zinc-Ion Batteries

The fundamental issues associated with Zn anodes prevent the commercialization of aqueous Zn ion batteries. To address this, a simple dip-coating method was used to coordinate a thin layer of branched polyethyleneimine (b-PEI) polymer onto the electrode surface. This process increases hydrophilicity and reduces interfacial resistance between the electrode and aqueous electrolyte. Consequently, electrolyte leaching from the hydrophilic polymer coating layer is prevented, charge distribution is uniform, and stable electrochemical performance is maintained over extended periods. In symmetric cell testing, the b-PEI@Zn anode exhibits a lifespan of over 1400 h (3 mA cm⁻², 1 mAh cm⁻²). Furthermore, full-cell tests, the b-PEI@Zn anode demonstrates higher capacity (+26.05%) and improved stability (95.4%) compared to the bare Zn anode (0.5 A g⁻¹). This study presents a practical surface modification strategy for Zn anodes and underscores the potential of innovative polymer-based electrode coatings for aqueous battery applications.