KOH pre-activation towards the enhanced discharge performance of the fluorinated needle coke cathode materials

In this work, fluorination of activated carbons derived from needle coke were employed to synthesize fluorinated carbons (CFx), which are utilized as cathode materials for high performance primary lithium batteries. The effect of KOH pre-activation of needle coke on the fluorination process and the performance of fluorinated activated-needle-coke (FANC) have been investigated through materials characterizations and electrochemical measurements. A great number of crystal defects and O-containing functional groups are developed during the KOH pre-activation process, dramatically increasing the reactivity between carbon and fluorine and leading to a much lower fluorination temperature. The FANC materials synthesized under lower temperature contain more semi-ionic FC bonds, ensuring better conductivity and higher discharge voltage plateaus. The FANC-250 synthesized at 250 °C shows the highest energy density of 2109.8 Wh kg−1 at a current density of 50 mA g−1. The highest power density reached 7920 W kg−1 at the current density of 4000 mA g−1. This work presents a novel approach to the design of CFx materials, aiming to expand the application field of Li/CFx batteries, employing a straightforward and low-cost method.