Fluorinated carbon nanotubes for electrochemical energy storage: from bonding chemistry to structure–property relationships

Fluorination provides an unusually direct means of tuning the bonding, electronic structure, surface chemistry, and interfacial behavior of carbon nanotubes (CNTs). The conversion of sp 2 carbon into fluorinated sp 3 environments produces semi-ionic and covalent C-F species whose relative abundance depends on the fluorination route, fluorine content, and CNT structure. These changes regulate conductivity, wettability, defect chemistry, thermal stability, and electrochemical reactivity. This review therefore organizes fluorinated carbon nanotubes (FCNTs) through a route-bonding-structure-property-performance framework. Direct gas-phase, atomic, plasma, liquid-phase, and solid-state fluorination routes are compared in terms of fluorination uniformity, bonding configuration, structural preservation, and scalability. The resulting structure-property relationships are then connected to four application roles: active Li/CF x and Na/CF x cathodes, interphase-forming components for alkali-metal batteries, adsorption and electrocatalytic interfaces, and conductive or structural electrode networks. Particular attention is given to the capacity-conductivity trade-off, the spatial distribution of fluorinated domains, and advanced characterization needed to resolve dynamic structural evolution. The review closes by distinguishing established consensus from unresolved questions and by identifying precision fluorination, operando multimodal characterization, standardized descriptors, and scalable manufacturing as priorities for FCNT-based energy storage.