Dynamic supramolecular polymer-driven hierarchical bilayer solid electrolyte interphase enabling durable high-energy lithium metal batteries

Practical Li metal batteries (LMBs) have been hindered by the instability of solid electrolyte interphase (SEI), arising from the inherently high reactivity of Li metal with liquid electrolytes, particularly carbonate systems, which in turn triggers persistent parasitic reactions and uncontrolled dendrite growth. Herein, we design a dynamic supramolecular polymer (DSP) coating that effectively stabilizes Li metal anodes and enables exceptional cycling performance in conventional carbonate electrolytes. The synthesized DSP coating spontaneously passivates the Li metal surfaces and regulates the interfacial chemical environment, thereby reconstructing the Li-ion (Li⁺) solvation structure at the anode interface. Such regulation induces the formation of a hierarchical bilayer inorganic-rich SEI comprising a mechanically robust outer layer (LiF, AlF₃) and an ion-conductive inner layer (Li₂S, Li₃N), which collectively suppresses electrolyte decomposition and homogenizes Li⁺ fluxes, ultimately prohibiting dendrite propagation. Consequently, the symmetric Li∥Li cells incorporating DSP coating exhibit outstanding cycling stability over 5000 h. Moreover, a 5.85 Ah DSP/Li∥LiNi_0.8Mn_0.1Co_0.1 (NMC811) pouch cell achieves an ultrahigh energy density (∼458.6 Wh kg⁻¹) with a low negative/positive capacity ratio (N/P ratio) of 0.75, maintaining a capacity retention of 87.1% after 40 cycles.