Doping-controlled silicon interlayers steer solid-electrolyte interphase formation in lithium metal batteries

초록

Current collectors in Li metal batteries are not merely electron pathways; they define the surface where electrolyte decomposition, corrosion, and solid-electrolyte interphase (SEI) formation begin. Here, we show that SEI formation can be steered by doping-controlled Si interlayers on Cu current collectors. Intrinsic, n-type, and ptype Si interlayers are used to modulate the surface electronic state while limiting co-variation in morphology and surface chemistry. Among them, p-type Si-coated Cu (p-Si@Cu) exhibits the highest work function and the most electron-deficient surface character, suppressing parasitic electron transfer to the electrolyte and reducing galvanic corrosion. In addition, p-Si@Cu promotes favorable salt adsorption and interfacial decomposition, directing SEI formation toward a thin, uniform, and LiF-enriched inorganic interphase. This electronically biased SEI suppresses continuous electrolyte consumption, promotes compact Li deposition, and improves Li plating/ stripping reversibility. As a result, p-Si@Cu delivers higher Coulombic efficiency and improved cycling performance compared with bare Cu in both Li||Cu cells and Li-free NCM811 full cells. These findings establish dopingcontrolled Si interlayers as electronic regulators of current collectors that steer SEI formation, providing a design principle for stabilizing Li metal interfaces.

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