Two-dimension tetragonal transition-metal carbides anodes for non-lithium-ion batteries
Searching for high-performance anode materials with high energy-density, fast kinetics, and good stability is a key challenge for non-lithium-ion batteries (NLIBs), such as Na+, K+, Mg2+, Ca2+, Zn2+ and Al3+ ion batteries. Here, we systematically investigate the performance of a new class of two-dimension tetragonal transition-metal carbides (tetr-MCs) by first-principles calculations, as anodes for NLIBs. The results show that tetr-MCs are ideal anode materials with good stabilities, favorable mechanical properties, intrinsic metallic properties, high theoretical capacities and fast ion diffusion rate for NLIBs. Among all tetr-MCs, we find that the energy barrier of Mg atom on tetr-TiC is only 54 meV and Al atom on tetr-VC is 101 meV, which are lower than that of the well-studied MXenes with the energy barriers of 230~500 meV, indicating that tetr-VC and tetr-TiC monolayers are promising anodes in NLIBs. Therefore, as compared to MXenes, tetr-MCs show many advantages in NLIBs applications, such as lower diffusion barrier (Minimum 54 meV), highly theoretical capacity (up to 1450 mAh g−1), and lower average open circuit (0.05~0.77 V). The results are of great significance for the experimental preparation of excellent anode materials for NLIBs.