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. • Monolayer C₄N exhibits intrinsic metallic conductivity and robust structural stability, enabling efficient electron transport and long-term cycling. • High theoretical capacities of 1295, 1079, and 1079 mAh·g −1 are achieved for Li, Na, and K ions, surpassing conventional graphite anodes. • Low diffusion barriers of 0.306, 0.093, and 0.086 eV for Li, Na, and K ions ensure superior rate capability and fast charge–discharge performance. • Optimal average open-circuit voltages (0.33 V for Li, 0.21 V for Na, 0.18 V for K) effectively suppress dendrite formation and enhance safety. • This study provides theoretical guidance for designing high-performance 2D anode materials for next-generation alkali metal-ion batteries.