Edge functionalization of graphyne nanoribbons for lithium-ion battery electrodes: a computational study

Lithium-ion batteries (LIBs) have become a vital part of the world's energy storage solutions over the past decades, mostly in the small electronics and electric vehicle markets. Lithium's high energy density and graphene's superior electronic properties make them a perfect combination for the most common LIBs used today. In recent years, other nanomaterials such as graphyne have emerged as highly promising candidates for innovative electrode designs. To explore this potential, the present study employs density functional theory (DFT) calculations to systematically investigate the structure and electronic properties of 56 unique graphyne compounds, evaluating their suitability as cathode materials for LIBs. A total of eight substituents were considered in this study, namely carbonyl, nitrile, nitro, carboxyl, trichloromethyl, trifluoromethyl, sulfeno, and dimethylamino groups. This study reveals that, among the functional groups analyzed, nitro and carbonyl groups consistently yielded the most significant enhancements in redox potential, achieving values as high as 5.0 V and 2.9 V, respectively. Other substituents did not impact the redox potential when compared to the pristine state with the exception of tetrasubstituted trifluoromethyl graphyne that reached a potential of 2.9 V. Moreover, the study demonstrates that the highest redox potentials in multi-substituted graphyne compounds were associated with locally distributed configurations, highlighting the benefits of controlled substitution within the graphyne framework.