Synergistic alkaline etching and nitrogen lattice occupation strategy enables gradient defluorinated cathode for high-performance Li/CFx batteries

A synergistic strategy of alkaline etching and nitrogen lattice occupation is proposed. • The constructed gentle gradient structure achieves dual optimization of the kinetic process and reaction sufficiency. • The F-RG-US/M exhibits 871 mA h g −1 at 0.1C with 87.8% retention at 20C. A higher F/C ratio leads to poor conductivity of the fluorinated carbon (CF x ) material, resulting in slow kinetics of the lithium‑fluorine reaction and thus hindering its application in special fields such as high-power energy storage. By designing and constructing a new type of CF x structure, it is of great significance for improving the rate performance of Li/CF x batteries. Herein, a synergistic strategy of alkaline etching and nitrogen lattice occupation is proposed to construct a CF x material (F-RG-US/M) with a gentle gradient defluorination. NaOH achieves gradient defluorination, forming a gentle step-like gradient structure in the material. This structure provides abundant Li + diffusion pathways while maintaining a reasonable F/C ratio to ensure specific capacity. Urea alters the distribution of electron clouds through nitrogen doping, enhances conductivity, and modulates the chemical environment of adjacent C F bonds. MWCNTs form an elastic conductive network, which further accelerates the transmission of electrons and ions. Consequently, F-RG-US/M exhibits outstanding electrochemical performance, delivering a specific capacity of 765 mA h g −1 with 87.8% capacity retention at a high rate of 20C. This work not only enables a sustainable upgrading and closed-loop recycling route for spent graphite but also provides a viable pathway for the industrial deployment of high-power CF x cathodes. A synergistic strategy of alkaline etching and nitrogen lattice occupation is proposed to construct a CF x material with a gentle gradient defluorination. This approach enables closed-loop recycling of spent graphite and offers a practical route for the large-scale industrial application of power type CF x materials. Download: Download high-res image (169KB) Download: Download full-size image