Fluorinated polymer-derived microporous carbon spheres for CFx cathodes with high energy density

Abstract

Fluorinated carbon (CF_x) compounds have extensive applications in lithium primary battery cathodes owing to their high energy density. In this investigation, a novel CF_x compound offering superior electrochemical properties was synthesized via a low-temperature fluorination process, utilizing Pluronic F127 as a template agent and microporous carbon spheres produced through soft template-assisted high-temperature carbonization and chemical activation as precursors, and by regulating the amount of soft template F127 added. The reduction in microsphere size, narrower particle size distribution, and introduction of defects contribute to augmenting the molar ratio of F to C (F/C) of CF_x while preserving the electrochemical activity of C-F bonds. The specific capacity of fluorinated polymer-derived microporous carbon spheres (FPMCSs) with a high fluorination degree rivals that of commercial fluorinated graphite (FG). The microsphere morphology and microporous structure not only furnish abundant sites for fluorination reactions in electrode processes but also facilitate Li⁺ diffusion, ensuring ample rate capability. The synthesized FPMCSs exhibited a peak specific capacity of 1079 mAh g^–1 and a maximum energy density of 2679 Wh kg^–1 (substantially surpassing the 2180 Wh kg^–1 of commercial FG). Hence, the prepared FPMCSs underscore the significance of selecting suitable carbonaceous materials and designing structures deliberately, showing promising potential for achieving high energy density in CF_x cathodes in the future, employing readily available and cost-effective raw materials.