Enabling ester-based electrolyte with dual-reinforced stable interfaces for high-efficiency anode-free lithium metal batteries

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Anode-free lithium metal batteries (AFLMBs) offer exceptional energy density but suffer from rapid capacity fade due to irreversible Li loss and interfacial instability. This work presents a cost-effective dual-salt electrolyte (0.6 M LiPF 6 + 0.6 M LiDFOB in EC/DMC/EMC 1:1:8 v/v) that simultaneously stabilizes the cathode and anode interfaces of AFLMBs. Preferential decomposition of LiDFOB promotes the formation of inorganic-rich, dual-reinforced interphases: a thin and uniform cathode-electrolyte interphase (CEI) and a stable solid-electrolyte interphase (SEI). The LiF/Li x BF y O z -rich CEI protects the Li-rich layered oxide cathode (LRO) from structural degradation and transition metal dissolution under high voltage, while the LiF/Li 2 C 2 O 4 /LiB x O y -rich SEI effectively suppresses parasitic reactions and Li dendrite growth on the Cu current collector, thereby mitigating the depletion of the limited Li inventory. This electrolyte design also modulates the Li + solvation structure, accelerating Li + desolvation, enhancing the Li + transference number, and improving the high-voltage stability. Consequently, Cu||LRO cells employing this dual-salt electrolyte achieve outstanding cycling stability with 70% capacity retention after 100 cycles, significantly outperforming conventional carbonate electrolyte. This dual-salt electrolyte also demonstrates applicability in other AFLMBs with compatible cathode materials, such as lithium vanadium phosphate and high‑nickel ternary cathodes, thus providing a promising strategy for achieving long-term cycling high-voltage AFLMBs.