Achieving Planar Zn Deposition Enabled by an Eco-Friendly and Mechanically Robust Dual Cross-Linking Dynamic Network Coating for Long-Lifespan Zn-Ion Batteries

Abstract

Aqueous Zn-ion batteries have attracted wide attention because of their low cost, intrinsic safety, and eco-friendliness. However, their development is seriously limited by the unstable Zn anode. To address this issue, this study designs an eco-friendly and mechanically robust dual cross-linking dynamic network coating on the Zn anode surface. The lithium polysilicate (LP) inorganic oligomer is rich in polar Si�O and Si−O bonds, which can be a facile platform to powerfully bond polar functional groups in a sodium alginate (SA) biopolymer. Interestingly, ionic cross-linking reactions occur between the composite coating (SL) and Zn 2+ ions in the electrolyte to in situ create a dual network with strong mechanical property and self-healing ability. This dualnetwork protective layer can not only effectively and durably suppress the upward growth of Zn dendrites but also prevent the direct contact between the Zn electrode and the aqueous electrolyte. Therefore, the cycle stability of the Zn anode in aqueous Zn-ion batteries is significantly improved: 2265 h vs 576 h at 2 mA cm −2 /2 mAh cm −2 for the symmetric cell and 81.1 mAh g −1 vs 31.4 mAh g −1 after 1000 cycles at 0.5 A g −1 for the Zn||MnO 2 full cell. This study provides a design strategy for eco-friendly Zn anode protection layers.