First-principles study of monolayer C4N as a high-performance anode material for lithium/sodium/potassium-ion batteries

Carbon–nitrogen (C N) compounds have recently emerged as a class of two-dimensional (2D) materials with outstanding electrical conductivity and structural robustness, making them attractive candidates for anode applications in lithium-, sodium-, and potassium-ion batteries. In this work, the electrochemical performance of monolayer C 4 N as an anode material for Li-, Na-, and K-ion storage was systematically investigated using density functional theory (DFT) calculations. The C 4 N monolayer exhibits intrinsic metallic behavior and strong adsorption toward Li, Na, and K atoms, ensuring stable binding configurations that promote high reversible capacity and long-term cycling stability. The calculated theoretical capacities for Li-, Na-, and K-ion storage are 1295, 1079, and 1079 mAh·g −1 , respectively, which exceed those of conventional graphite anodes. The average open-circuit voltages are confined within the optimal window of 0–1 V, favoring the suppression of dendrite growth during cycling. Moreover, the diffusion energy barriers of 0.306, 0.093, and 0.086 eV for Li, Na, and K ions, respectively, indicate rapid ion transport and superior rate performance. These results demonstrate that monolayer C 4 N is a highly promising 2D anode for next-generation metal-ion batteries, offering valuable theoretical insights into the rational design of high-performance energy storage materials.