V4C3 MXene: a Type‐II Nodal Line Semimetal with Potential as High‐Performing Anode Material for Mg‐Ion Battery

Abstract We have used density functional theory simulations to explore the topological characteristics of a new MXene‐like material, V 4 C 3 , and its oxide counterpart, assessing their potential as anode materials for Mg‐ion batteries. Our research reveals that V 4 C 3 monolayer is a topological type‐II nodal line semimetal, protected by time reversal and spatial inversion symmetries. This type‐II nodal line is marked by unique drumhead‐like edge states that appear either inside or outside the loop circle, contingent upon the edge ending. Intriguingly, even with an increase in metallicity due to oxygen functionalization, the topological features of V 4 C 3 remain intact. Consequently, the monolayer V 4 C 3 has a topologically enhanced electrical conductivity that amplifies further upon oxygen functionalization. During the charging phase, a remarkable storage concentration led to a peak specific capacity of 894.73 mAh g −1 for V 4 C 3 , which only decreases to 789.33 mAh g −1 for V 4 C 3 O 2 . When compared to V 2 C, V 4 C 3 displays a significantly lower specific capacity loss due to functionalization, demonstrating its superior electrochemical properties. Additionally, V 4 C 3 and V 4 C 3 O 2 exhibit moderate average open‐circuit voltages (0.54 V for V 4 C 3 and 0.58 V for V 4 C 3 O 2 ) and energy barriers for intercalation migration (ranging between 0.29–0.63 eV), which are desirable for anode materials. Thus, our simulation results support V 4 C 3 potential as an efficient anode material for Mg‐ion batteries.