Graphene acid-enhanced interfacial layers with high Zn²⁺ ion selectivity and desolvation capability for corrosion-resistant Zn-metal anodes

Utilizing an interfacial layer to stabilize Zn-metal anodes has been extensively explored, often accompanied by inhibition of Zn dendrites. However, most interfacial layers primarily delay Zn²⁺ ion transport/transfer, leading to slow Zn deposition due to the ion kinetics hindrance. Basically, this ionic hysteresis effect is inherent to all interfacial layers and will cause unstable Zn deposition over extended cycling periods. Here, we present a simple composite interfacial layer composed of graphene acid (GA) and cellulose nanofibers (CNFs). In the CNF/GA layer, a delicate balance between the rapid Zn²⁺ transport/transfer and uniform Zn deposition is achieved. The presence of GA not only demonstrates excellent ion selectivity and suppresses corrosion reactions, but also promotes Zn²⁺ transport/transfer, significantly reducing the desolvation energy of Zn²⁺ ions. Consequently, the symmetric cell with CNF/GA coatings achieves a highly stable cycling life of 2920 h, surpassing previous reports using graphene-based and CNF-based protecting layers. Moreover, the full cell based on the CNF/GA protected anodes exhibits excellent long-term stability and maintains an ultra-stable self-discharge retention of 99% after 24 h of standing. These findings provide valuable insights for the development of protective layers for Zn-metal anodes and future grid-scale Zn battery deployment.