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

Abstract

Because of the presence of electrochemically inactive C-F₂ 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-F₂ 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.