Insights into TiNT/VS (T = F, O, OH) heterostructures as innovative anode materials for lithium/sodium/magnesium-ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-08, Vol.12 (34), p.238-2322
• Main Authors: Ma, Feng-Ming, Zhao, Xiao-Meng, Luo, Han-Bai, Shang, Chun-Liang, Gao, Hui-Min, Wang, Xiao-Lin
• Format: Article
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d4ta02761b

To promote the development of anode materials for rechargeable batteries, we investigated the relationships between the structure characteristics and the electronic, mechanical, adsorption, diffusion and electrochemical properties of the designed Ti 3 N 2 T 2 /VS 2 (T = F, O, OH) heterostructures for lithium/sodium/magnesium-ion batteries using density functional theory calculations. Three optimal heterostructures with different terminations, Ti 3 N 2 F 2 /VS 2 , Ti 3 N 2 O 2 /VS 2 and Ti 3 N 2 (OH) 2 /VS 2 , were selected, and the mechanisms of charge transfer and ion diffusion were expounded clearly. These heterostructures can be used as novel anode materials based on excellent thermal stability, metallicity, mechanical stability, adsorption and diffusion performance. The results indicate that the main contributors to the metallicity are the d-orbital electronic states derived from Ti and V. The intrinsic nature of metallicity guarantees a good electrical conductivity that enables rapid charge migration and accelerates the redox process. The ion insertion not only affects the density of states distributions of the heterostructures, but also enhances their Fermi levels. The amount of charge transfer from a metal ion to VS 2 is more than that to Ti 3 N 2 T 2 at the respective interlayers of Ti 3 N 2 F 2 /VS 2 and Ti 3 N 2 (OH) 2 /VS 2 , while the opposite trend appears for Ti 3 N 2 O 2 /VS 2 . The monolayer that gains more charges from the ion corresponds to the charge acceptor in the pristine heterostructure without ion adsorption. The most favorable ion-diffusion path between two optimal adsorption sites inevitably passes through the second optimal adsorption site with the second smallest adsorption energy. Considering the structural integrity, strong adsorption abilities, low diffusion energy barriers, high capacities and suitable open-circuit voltages, Ti 3 N 2 F 2 /VS 2 and Ti 3 N 2 (OH) 2 /VS 2 are proposed to be promising high-performance anode materials for SIBs and LIBs/MIBs, respectively, and Ti 3 N 2 O 2 /VS 2 is an ideal anode material for LIBs/SIBs/MIBs. Novel Ti 3 N 2 T 2 /VS 2 (T = F, O, OH) heterostructures with excellent thermal stability, metallicity, mechanical stability, adsorption, diffusion and electrochemical performance are designed and tested as anode materials for LIBs/SIBs/MIBs.