Acetylene/argon mixture plasma to build ultrathin carbon bridge of CF_x/C/MnO₂ for high-rate lithium primary battery

Forming an ultrathin conducting layer on a fluorinated carbon (CF_x) surface for reducing severe electrochemical polarization in lithium/fluorinated carbon primary batteries (Li/CF_x) remains a considerable challenge for achieving batteries with excellent rate capability. Herein, CF_x was modified by using acetylene/argon mixture plasma combined with MnO₂ particles. The CF_x/C/MnO₂ composite effectively reduced the voltage hysteresis and improved the electrochemical performance of Li/CF_x. The excellent rate performance of CF_x/C/MnO₂ was due to the high electrochemical activity provided by the atomic-scale conductive carbon layer and ultrafine MnO₂ particles. Compared with pristine CF_x, the charge transfer resistance of the optimized CF_x/C/MnO₂ decreased from 218.5 to 48.2 Ω, the discharge rate increased from 2C to 10C, and the power density increased from 3.11 to 13.44 kW·g⁻¹. The intrinsic reason for the enhanced rate performance was attributed to the fact that the ultrathin carbon layer acted as a conductive bridge to reduce the voltage hysteresis at the initial stage of the Li/CF_x discharge, and the high electrochemical activity of the ultrafine MnO₂ particles provided a faster lithium-ion diffusion rate.