Breaking the 5.5 V barrier: Lithium nitrate-stabilized electrolyte for wide-temperature and high-voltage applications

Overcoming the trade-off between high-voltage stability and wide-temperature performance, especially at low temperatures, in lithium-ion batteries (LIBs) requires innovative electrolyte design. While carbonate-based electrolytes dominate commercial applications for their graphite compatibility, their strong solvent-ion interactions and elevated viscosity below −20 °C significantly compromise low-temperature performance. They also lead to unstable reactions at the electrode surfaces under high voltage. We report a LiNO 3 -tailored electrolyte system that simultaneously achieves an unprecedented 5.54 V electrochemical window and stable operation down to −40 °C. By coupling low-melting carboxylate esters with fluoroethylene carbonate and LiNO 3 additives, the formulation constructs anion-dominated solvation structures. The designed electrolyte suppresses solvent decomposition at high voltage while maintaining ionic conductivity at ultra-low temperatures. The high-loading full cells (G/NCM811, 12.68 mg cm −2 ) achieve 70 % capacity retention at −40 °C relative to room temperature performance, sustaining 89 % capacity after 350 cycles at 1C at 25 °C. Moreover, the novel electrolyte enables G/NCM811 pouch batteries to charge and discharge at a high voltage of 5.1 V, achieving a second-cycle coulombic efficiency of 91.22 %. Furthermore, the new electrolyte enables the Li/NCM811 cell to operate at high temperatures of 75 °C and supports rapid charging and discharging of the high-loading G/NCM811 full cell at 70 °C. This work provides a promising design principle for extreme-condition electrolytes through synergistic nitrate chemistry and solvation engineering.