Dual-phase engineering of CFx electrode and interphase enables low-temperature Li||CFx batteries

Low-temperature Li||CFx batteries undergo performance degradation due to the insulating nature of CFx and sluggish Li+ kinetics. Herein, we present a dual-modification strategy integrating porous positive electrode architecture design with customized electrode-electrolyte interphase engineering to overcome these limitations. Our approach features: (i) plasma-enhanced chemical vapor deposition-constructed mesoporous CFx with conformal carbon coating, and (ii) electrolyte-mediated in situ formation of a sulfur-rich inorganic interphase layer on CFx surface. The engineered porous framework establishes efficient Li+ diffusion channels, while the electrolyte-derived interphase significantly enhances Li+ transport and desolvation kinetics. Moreover, the carbon coating substantially improves electronic conductivity and suppresses LiF stacking. The optimized Li||CFx system delivers capacities of 428.4 mAh g−1 at −50 °C and 2 A g−1, and 333.4 mAh g−1 at −70 °C and 0.1 A g−1. Practical 5 Ah pouch cells deliver competitive specific energies of 470 and 332 Wh kg−1 at −50 and −70 °C under 0.01 A g−1, respectively. Li||CFx batteries exhibit severe low-temperature degradation owing to insulating CFx electrodes and sluggish Li+ kinetics. The authors propose a dual-modification strategy combining carbon-coated porous CFx cathodes with an electrolyte-derived interphase, which accelerates Li+ transport and boosts performance at low temperatures.