Tailoring C-F Configurations in O-CFx Cathodes via Wet Chemistry for 600 Wh kg-1 Li/O-CFx Pouch Cells

Abstract

Li/CFx primary batteries, featuring an ultra-high theoretical energy density (2180 Wh kg-1), have been widely employed in critical military and commercial applications, e.g., deep-space and deep-sea exploration. However, the underlying relationship between their specific C-F configurations and rate performance has not been fully understood. Herein, a scalable synthesis strategy for oxidized CFx (O-CFx) is reported. Notably, an oxidation-time regulated C-F configurations, including F/C ratio, type of C-F bonds and structure of carbon frameworks, can be synergistically achieved via defluorination followed by re-fluorination of pristine CFx. Consequently, electrons from adjacent heteroatoms and functional groups occupy the antibonding orbitals of C-F bonds (\sigma_{C-F}^\ast), thereby increasing the proportion of electrochemical active semi-ionic C-F bonds by nearly twofold in O-CFx. Benefiting from the optimized C-F configurations, Li/O-CFx batteries deliver a power density of 8.44×104 W kg-1 at 50 C and operate robustly across an all-climate temperature range (-40 °C to 60 °C). 20 Ah-level Li/O-CFx pouch cells achieve impressive energy densities of 614.75 Wh kg-1 and 693.92 Wh L-1 at 0.5 C. This work proposes a novel design strategy for all-climate Li/CFx batteries featuring dual-high power and energy densities.