Electrolyte engineering enables high-energy Li‖CFx battery operation at ultralow temperatures†
Abstract
A lithium metal‖carbon fluoride (Li‖CFx) primary battery offers high energy density and long shelf-life but suffers from poor performance at low temperatures. We report a linear ester-based electrolyte comprising ethyl acetate (EA) and ethyl trifluoroacetate (ET) with LiBF4 salt to address this challenge. EA served as the primary solvent, while ET acted as an anti-solvent, weakening Li+ coordination due to its strong electron-withdrawing fluorine atoms. This unique solvation structure enhanced Li+ transport for an Li‖CFx battery, delivering a high discharge capacity of 706 mA h g−1 at −40 °C and 395 mA h g−1 at −60 °C.