Helical fluorinated carbon nanotubes/iron(iii) fluoride hybrid with multilevel transportation channels and rich active sites for lithium/fluorinated carbon primary battery

Lithium/fluorinated carbon (Li/CFx) primary battery is a promising energy supply device with high energy density. However, poor electrochemical capabilities such as the initial voltage delay phenomenon and the large polarization have obstructed their applications. The electrochemical performance of CFx primarily depends on the feature of the carbon source and the corresponding fluorination technique. Herein, we developed a high energy density Li/CFx battery by employing helical carbon nanotubes (HCNTs) as the carbon source. In detail, the precise control of the fluorination temperature was designed at the range of 250–400°C to tune the F/C ratio of CFx. Furthermore, the high F/C ratio of fluorinated HCNTs (F-HCNTs) reaches about 1.43, which surpasses the highest theoretical value in fluorinated crystalline carbon materials. Due to the active rich fluorination sites provided by the periodical insertion of the carbon pentacyclic (C5) and heptacyclic (C7) rings, HCNTs exhibited a defect-rich feature and F-HCNTs have a nodular shape. These features favor to enhance the transport of lithium ions and allow more C–F bonds to react with lithium ions, leading to a high energy density of 2133.13 W h/kg. This novel material offers an alternative approach for lithium primary battery being great potential in actual applications.