Ultraviolet-Induced Formation of Silver Nanoparticles Anchored by the Conductive-Viscous Polypyrene–Polydopamine Copolymer on CFx Surface for High-Power Li/CFx Battery

Abstract

The high energy density lithium/carbon fluoride (Li/CF_x) battery meets the challenge of limited high-rate discharge performance due to the low intrinsic conductivity of CF_x. Herein, an inorganic/organic (Ag/PPy-PDA) synergistic conductivity strategy is developed to suppress CF_x polarization, addressing the ultrahigh rate of CF_x batteries for the high F content. Bioinspired by mussel surface chemistry, UV-mediated synthesis of Ag nanoparticles on CF_x surfaces is achieved through a polypyrene–polydopamine (PPy-PDA) copolymer-assisted reduction of a silver ammonia solution. During UV irradiation, the copolymer serves a dual function: stabilizing C–F bonds against alkaline degradation in silver ammonia solutions and hindering the defluorination under UV exposure. Detailed mechanistic studies reveal synergistic adhesive growth and surface-protection effects, enabling the precise Ag nanoparticle assembly on CF_x. The as-designed CF_x@PPy-PDA@Ag composite possesses the advantage of a high F/C ratio, excellent inorganic/organic conductive path, and good wettability of the electrolyte. Therefore, the optimal Li/CF_x battery (CF_x@PPy-PDA@Ag-10%) achieved a high discharge rate of 15000 mA·g^–1, delivering a high-power density of 22,404.37 W·kg^–1. This inorganic/organic (Ag/PPy-PDA) synergistic conductivity strategy lights up the high-rate Li/CF_x batteries with a high F/C ratio. A DFT calculation is conducted for CF_x, and the result shows that the conductivity is significantly improved, and the interaction between C–F bonds was significantly weakened after the Ag NPs are deposited on the surface.