Electrolyte Design Enables Rechargeable LiFePO₄/Graphite Batteries from −80 °C to 80 °C

Abstract

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 Li⁰ 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.