Tailoring C–F configurations in O–CFx cathodes via wet chemistry for 600 Wh kg−1 Li/O–CFx pouch cells

Abstract

Li/CF_x 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 CF_x (O–CF_x) is reported. Notably, oxidation-time regulated C–F configurations, including the 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 CF_x. Consequently, electrons from adjacent heteroatoms and functional groups occupy the antibonding orbitals of C–F bonds , thereby increasing the proportion of electrochemically active semi-ionic C–F bonds by nearly twofold in O–CF_x. Benefiting from the optimized C–F configurations, Li/O–CF_x batteries deliver a power density of 8.44 × 10⁴ W kg⁻¹ at 50C and operate robustly across an all-climate temperature range (−40 °C to 60 °C). 21 Ah-level Li/O–CF_x pouch cells achieve impressive energy densities of 614.75 Wh kg⁻¹ and 693.92 Wh L⁻¹ at 0.5C. This work proposes a novel design strategy for all-climate Li/CF_x batteries featuring dual-high power and energy densities.