Advanced LiTFSI-LiPF 6 Dual-Salt Electrolyte for High-Power and Wide-Temperature Operation of Lithium-Ion Batteries

The development of advanced electrolytes is critical to enabling lithium (Li)-ion batteries (LIBs) with high energy density, power capability, and operational stability under extreme conditions. Here, we introduce a dual-salt controlled-solvation electrolyte designed for LIBs with LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode and graphite (Gr) anode at practical areal loadings (4.0 and 4.5 mAh cm −2 , respectively). Despite lower ionic conductivity and higher viscosity compared to conventional carbonate electrolytes across all temperatures, the optimal dual-salt controlled-solvation electrolyte demonstrates superior electrochemical performance. It shows an exceptional oxidative stability above 4.9 V vs Li/Li⁺, enables Gr||NMC811 cells to achieve outstanding cycling stability similar to the conventional electrolyte in 500 cycles, but show remarkable high-temperature stability during cycling and storage at 60 °C, superior discharge rate performance at high current densities (up to 3 C), and better low-temperature (−20 °C) discharge performance. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy reveal the optimal dual-salt electrolyte generates thinner and more robust inorganic electrode/electrolyte interphase layers compared to those formed in the conventional carbonate electrolyte, minimizing parasitic reactions and heat release. These results highlight the potential of this optimal dual-salt electrolyte to transform LIB performance for high power applications across wide temperature range, paving the way for next-generation energy storage.