Dual‐Salt Concentrated Electrolyte for High‐Voltage and Long‐Life Aluminum‐Based Lithium‐Ion Batteries

The monolithic aluminum (Al) foil anode enables streamlined manufacturing and low cost, yet is hampered by mechanical stress, pulverization, and lithium trapping, hindering its practical application. Here, a novel dual‐salt highly concentrated ether‐based electrolyte, LiFSI/LiDFOB/DME (denoted as LDF), is formulated to stabilize high‐voltage Al‐based lithium‐ion batteries. By reconstructing the Li + solvation structure at the molecular level, the dual salts synergistically form a stable, fluoride‐ and boron‐rich cathode electrolyte interphase (CEI), thereby effectively suppressing electrolyte decomposition at high voltage. In parallel, this electrolyte design significantly mitigates corrosion on the Al current collector. A thin, uniform solid electrolyte interphase (SEI) layer with a high Young’s modulus is also induced on the Al anode side. Benefiting from this dual interfacial protection mechanism, the Al||NCM523 full cell achieves 80% capacity retention after 200 cycles, operating within a 2.0–4.0 V range under a high mass loading of ~7.0 mg cm −2 . Moreover, when coupled with a high‐nickel NCM811 cathode (charged to 4.5 V vs. Li + /Li; full‐cell window, 2.0–4.2 V), the system sustains stable cycling for over 100 cycles. By demonstrating the compatibility of 40 µm Al foil with a high‐voltage cathode in an ether‐based system, this establishes a practical strategy for high‐energy‐density, durable Al‐based lithium‐ion batteries.