Thermodynamic and kinetic properties of 2D carbon selenide for efficient sodium-ion batteries (SIBs)

Abstract

Despite the promise of sodium-ion batteries (SIBs) for large-scale energy storage, the development of high-performance anode materials remains a critical challenge. Here, we report that the two-dimensional β-phase carbon selenide (β-CSe) monolayer exhibits remarkable Na-ion storage properties identified through comprehensive first-principles calculations. The buckled honeycomb structure demonstrates exceptional stability with positive phonon frequencies and preserved C-Se bonds during molecular dynamics at both room temperature (300 K) and elevated temperature (400 K). Na adsorption occurs preferentially at hollow sites with strong binding energies (−2.95 eV on C-side) and substantial charge transfer (0.82|e|), thermodynamically favoring uniform Na distribution which may help suppress dendrite formation. Strikingly, the material exhibits ultrafacile Na diffusion with maximum energy barriers of only 0.019-0.021 eV, among the lowest reported for SIB anodes, suggesting exceptional rate performance. Basin-hopping Monte Carlo simulations reveal a theoretical capacity of 589 mAh/g with an average insertion potential of 1.11 V, while the material advantageously transitions from semiconductor to metallic behavior upon Na insertion. The anisotropic Poisson's ratio (as low as 0.05) further minimizes volume changes during cycling. These findings establish β-CSe as a promising candidate for high-performance SIB anodes and provide valuable insights for designing advanced battery materials.