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

Low-temperature Li||CF_x batteries undergo performance degradation due to the insulating nature of CF_x 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 CF_x with conformal carbon coating, and (ii) electrolyte-mediated in situ formation of a sulfur-rich inorganic interphase layer on CF_x 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||CF_x 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.