Entropy-Regulated Dielectric Friction in 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 scenarios. 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 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 of Li+ solvation chemistry and expands the design principles for electrolytes under extreme temperatures.