Self-assembled nanointerfaces with highly efficient Li ⁺ transport for ultra-stable lithium metal batteries

Unstable electrode-electrolyte interface and uncontrolled lithium dendrite growth lead to rapid capacity decay and safety hazards, significantly hindering the practical application of lithium metal batteries (LMBs). Effective interfacial protection coupled with facilitated Li⁺ transport is therefore essential. Herein, we present a self-assembled block copolymer (BCP)-based artificial polymer solid electrolyte interphase (APSEI) that integrates ion transport channels with localized chemical regulation to regulate Li⁺ transport kinetics and significantly enhance the cycling performance of LMBs. The BCPs containing polystyrene domains and amide/sulfonic acid bearing segments self-assemble into tunable nanostructures via control of functional block volume fraction. Especially, the double gyroid (DG) morphology establishes a three-dimensional, interconnected ion network with a high cation transference number, ensuring uniform Li⁺ flux and homogeneous deposition. The dual-functional groups within the functional blocks further orchestrate Li⁺ desolvation and diffusion at the interface. As a result, symmetric Li||Li cells with a DG-structured PS-<em>b</em>-PPFPA(AESA) (S-<em>b</em>-F(AESA)) exhibit stable cycling for over 1000 hours at 1 mA cm^-2 and 1 mAh cm^-2. Moreover, full-cells assembled with high-loading LiFePO₄ cathodes (11.6 mg cm^-2) achieve a high capacity retention of 90.6% and 99.9% Coulombic efficiency after 300 cycles at 1 C. This morphology-chemistry co-design provides a generalizable blueprint for interfacial stabilization in next-generation batteries.