The electrochemical performances of fluorinated hard carbon as the cathode of lithium primary batteries

In this paper, a series of hard carbon was firstly fluorinated via gas-phase fluorination and their electrochemical performances were adjusted by varying fluorination temperature. It is found that the F/C ratios of fluorinated hard carbon increased with rising temperature consecutively, whereas the discharge plateau decreased due to the lowered content of semi-ionic C–F bond. The fluorinated hard carbon obtained at 390 °C approximately exhibited the highest specific capacity of 922.6 mAh g-1 with the discharge potential of 2.7 V (vs. Li/Li+), which delivered the energy density of 2466 Wh kg-1, higher than the theoretical value (2180 Wh kg-1) of commercial fluorinated graphite. In addition, the sample obtained at about 370 °C delivered good rate capability that the capacity retention ratio was 74.3% even at current density of 5C. Hard carbon, as one of widely applied anode materials in sodium ion batteries, was firstly fluorinated in this study, and the superior electrochemical performances than fluorinated graphite as well as its low cost and scalable product demonstrated its great potential practicability in the field of lithium primary batteries to replace the commercial fluorinated graphite in the market.