Relatively low temperature defluorination and carbon coating in CFx by dimethyl silicone oil/polyethylene glycol for enhancing performance of lithium primary battery

• An efficient low-temperature (350 °C) gas–solid defluorination strategy is used to remove the inactive C-F 2 and inhibit the high-temperature decomposition of C-F in CF x . • The discharge platform of CF x -Si-C is 2.7 V at 0.01C, with a discharge capacity of 859.1 mAh g −1 and the energy density of 1889.7 Wh kg −1 . • CF x -Si and CF x -Si-C has significantly higher than diffusion rate of Li ions of CF x . Because of the presence of electrochemically inactive C-F 2 bond and poor electronic conductivity of C-F, the discharge performance of lithium fluorocarbon (Li/CF x ) batteries is limited, despite their extensive use in commercial fields. In this study, dimethyl silicone oil/polyethylene glycol was adopted to improve the performance of CF x through relatively low temperature (350 °C) defluorination and carbon coating. The uniform mixing of dimethyl silicone oil with CF x and the subsequent gas–solid reaction enables mild defluorination, transforming C-F 2 into semi-ionic C-F with high conductivity. Furthermore, this dimethyl silicone oil/ polyethylene glycol treated CF x under 350 °C prevent the thermal decomposition of C-F during both of the defluorination and carbon coating process, resulting in improving the electrical performance and capacity protection of CF x . Specifically, the modified CF x cathode exhibits a 2.7 V discharge platform, a discharge capacity of 859.1 mAh/g and the energy density of 1889.7 Wh kg −1 at 0.01C. This approach allows for large scale adjustments of CF x with excellent performance, making it easy to industrialization.