Entropy-regulated dielectric friction in a eutectic electrolyte unlocks 150 °C high-performance Li metal batteries

Abstract

The poor high-temperature performance of conventional electrolytes limits the application of Li metal batteries under extreme conditions. Here, we propose a novel insight into dielectric friction-regulated electrolytes and, based on the designed high-entropy eutectic electrolyte (HEEE), successfully achieve long-term operation of Li metal batteries at 150 °C. The structurally diverse anions within the HEEE create a disordered dielectric environment, disrupting the long-range cooperativity of dielectric polarization relaxation, reducing the hindrance of dielectric friction to Li⁺ transport, and thereby suppressing dendrite growth. Also, the disordered dielectric environment promotes an inorganic-rich solid electrolyte interphase on the Li metal anode, endowing the HEEE with excellent electrode compatibility. Consequently, Li||Li cells operate for over 6000 h at 25 °C, 8820 h at 80 °C, and 1000 h at 150 °C. V₂O₅||Li cells maintain a capacity of 68.5 mAh g⁻¹ even after 200 cycles at 150 °C. Importantly, 1.07 Ah LiFePO₄||Li pouch cells operate for over 200 h at 80 °C, successfully pass the nail penetration test, and power a micro-truck. This work provides a fundamental insight into Li⁺ solvation chemistry and expands the design principles for electrolytes under extreme temperature conditions.