Skin barrier repair-inspired ultralight interlayer for practical anode-free lithium metal batteries

Abstract

Anode-free lithium metal batteries (AFLMBs) have significant potential in high-energy-density and high-safety storage applications. Nevertheless, their practical utilization remains constrained by detrimental interface evolution and the resulting rapid capacity degradation and poor Coulombic efficiency. Here, we first design a sodium hyaluronate (SH) layer integrating suitable dielectric environment, high mechanical robustness, abundant lithiophilic groups, and uniformly dispersed molecular short-chains. Correspondingly, optimized interfacial evolution at the Cu substrate-electrolyte interface benefits from synergistic modulation mechanisms of the SH layer involving: i) inducing uniform adsorption and enrichment of Li⁺ at its own abundant lithiophilic sites, followed by the well-organized migration and nucleation of Li adatoms at a microscale, eventually achieving uniform Li deposition/dissolution (8 mAh cm^–2); ii) driving the formation of the “rigidity-with-flexibility” interphase composed of inorganic-rich SEI and soft organic SH framework to suppress large volume expansion and severe side reactions. Consequently, the SH layer endows the Li||SHCu and SHCu||LFP cells with ultra-high cycling stability. Further, the practical SHCu||LRMO pouch-type AFLMBs exhibits a high energy density (560 Wh kg^–1, 1059 Wh L^–1) and an initial Coulombic efficiency (95.5%). Our work reveals the promise of biomaterials as artificial layers in tuning the interfacial behaviours and electrochemical performance of AFLMBs.