An entropy-driven multi-anionic electrolyte for Li-ion batteries with high voltage stability and superior temperature adaptability

Abstract

Simultaneously achieving high-voltage stability and low-temperature adaptation in lithium-ion batteries (LIBs) remains a critical challenge, as conventional ether-based electrolytes suffer from insufficient oxidative stability while ester-based systems exhibit sluggish ion transport kinetics. Herein, an entropy-driven multi-anionic ether electrolyte (HE-DIG) is designed to alleviate the abovementioned problems. Theoretical computations elucidate that multi-anion coordination in HE-DIG facilitates the formation of weakened solvation structures while concurrently expanding electronic bandgaps. This synergistic modulation significantly mitigates limitations imposed by Li⁺ desolvation kinetics at low temperatures and effectively suppresses oxidative decomposition under high-voltage conditions. As expected, LiNi_0.52Co_0.2Mn_0.28O₂ (NCM523) in HE-DIG exhibits higher capacity, stable median voltage and better cycling performance than commercial ester electrolytes at both 25 °C and −20 °C. The preferential decomposition of LiNO₃ and LiDFOB generates a cathode−electrolyte interphase (CEI) rich in inorganic species. In addition, Li_1.2Ni_0.2Mn_0.6O₂ (LNMO) displays superior long-term cycling stability, retaining 83.8% capacity after 1000 cycles at −20 °C in HE-DIG. Remarkably, a 12 A h pouch cell with a graphite anode, NCM523 cathode, and the HE-DIG electrolyte delivers outstanding cycling stability, maintaining 91.6% capacity after 800 cycles at a rate of 8C. This work provides a solvation-tuning strategy leveraging anion diversity for advanced battery systems.