Cyclo[18]carbon as a tunable anode platform for sodium-ion batteries: insights from halide doping
摘要
The increasing demand for low cost and economically viable energy storage systems has intensified interest in sodium-ion batteries as an alternative to lithium-ion systems. Despite this progress, the development of high-performance anode materials with large surface area and a suitable cell potential remains a major challenge. Although cyclocarbons have been explored as dopants to facilitate reversible metal-ion diffusion in carbon-based electrodes, their application as primary anode materials remains unexplored. In this DFT study, we examine sp-hybridized cyclocarbon C18 as a promising anode material and suggest a strategy to improve its electrochemical performance. The adsorption energies of sodium-ion in the gaseous and solvent phases were − 21.98 and − 57.78 kcal mol− 1, indicating stable charge-discharge species but insufficient cell potential. To solve this issue, halide dopants (F, Cl, and Br) were introduced to the electronic environment of C18Na. The adsorption energies for Na/F@C18, Na/Cl@C18, and Na/Br@C18 neutral complexes are − 15.61, − 10.67, and − 12.19 kcal mol− 1, respectively. Notably, Na/Br@C18 shows an appropriate cell voltage of 0.92 V in the gaseous phase and 0.62 V with toluene, falling within a desirable range for NIB anodes. Overall, this study shows that cyclocarbon-based anode nanomaterials are a low-cost, tunable, and high-performance platform for developing next-generation sodium-ion energy storage technologies.