A novel one-step method to prepare N, S Co-doped sub-fluorinated carbon electrode materials for ultrahigh-rate lithium-fluorinated carbon battery

Abstract

To improve the electrochemical performance of fluorinated carbon (CFx) for lithium-fluorinated carbon batteries, the nitrogen and sulfur co-doped sub-fluorinated carbon cathode material (NS-sCFx) is synthesized by a one-step method of heteroatom doping and defluorination. Experimental results confirm that nitrogen and sulfur elements are successfully doped on the surface of CFx material, and the surface fluorinated degree is reduced. DFT calculations and experimental results demonstrate that the heteroatoms co-doping and defluorination can generate a conductive interface, increase activation sites, and induce charge redistribution, producing a superior transfer rate of electrons and lithium ions. Hence, the NS-sCFx cathode material possesses excellent electrochemical properties, large specific capacity, high-rate performance, high power density, and no initial voltage delay. The Li/NS-sCFx battery delivers a specific capacity of 590.4 mAh·g−1 with a voltage plateau of 1.997 V at 20 C without initial voltage delay, corresponding to a power density is 35946 W kg−1. Extraordinarily, an ultra-high power density of up to 107100 W kg−1 at 70 C is achieved without significantly initial voltage delay. This study reveals the functional mechanism of NS-co-doping and defluorination to improve the electrochemical performance of NS-sCFx material, which can be used as a reference for the design and development of related electrode materials.