Electrolyte Design Enables Rechargeable LiFePO/Graphite Batteries from -80 °C to 80 °C.

Lithium iron phosphate (LFP)/graphite batteries have long dominated the energy storage battery market and are anticipated to become the dominant technology in the global power battery market. However, the poor fast-charging capability and low-temperature performance of LFP/graphite batteries seriously hinder their further spread. These limitations are strongly associated with the interfacial lithium (Li)-ion transport. Here we report a wide-temperature-range ester-based electrolyte that exhibits high ionic conductivity, fast interfacial kinetics and excellent film-forming ability by regulating the anion chemistry of Li salt. The interfacial barrier of the battery is quantitatively unraveled by employing three-electrode system and distribution of relaxation time technique. The superior role of the proposed electrolyte in preventing Li plating and sustaining homogeneous and stable interphases are also systematically investigated. The LFP/graphite cells exhibit rechargeability in an ultrawide temperature range of -80 °C to 80 °C and outstanding fast-charging capability without compromising lifespan. Specially, the practical LFP/graphite pouch cells achieve 80.2 % capacity retention after 1200 cycles (2 C) and 10-min charge to 89 % (5 C) at 25 °C and provide reliable power even at -80 °C.