Nitrogen-enriched, graphitizable carbon fibers derived from an organic pigment for stable high-energy batteries

Metallic lithium (Li) anodes are ideal for Li-ion batteries owing to the high specific capacity and low redox potential of Li. However, the practical applications of metallic Li anodes are hindered by dendrite formation, low Coulombic efficiencies, and safety risks. In order to mitigate these challenges, one effective strategy is to use carbon-based current collectors. This study highlights the potential of nitrogen-enriched, graphitizable carbon fibers Nitrogen-enriched, graphitizable carbon fibers (NGC), prepared by electrospinning a C.I. Pigment Red 122 solution, as lithiophilic and porous current collectors for Li-ion and Li-metal batteries. The nitrogen and oxygen contents and carbon crystallinity of the fibers are controlled by adjusting carbonization temperatures from 600 to 1500 °C. In both Li-ion and Li-sulfur batteries, NGC-T600, carbonized at 600 °C, achieves the highest specific capacity owing to abundant surface-functional groups (C=O and C–N). Conversely, in Li-metal batteries, NGC-T1000, carbonized at 1000 °C, demonstrates the most stable cycling performance with a high Coulombic efficiency under high areal current densities and larger Li deposition capacities. These findings suggest that the interplay between nitrogen-associated bonds and degree of crystallinity in carbon scaffolds influences the Li storage mechanisms, electrochemical reversibility, and kinetics of the NGC, yielding different electrochemical behaviors in Li-ion and Li-metal batteries.