Meng Qiangqiang, Hu Alice, Zhi Chunyi, Fan Jun
Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China.
Phys Chem Chem Phys. 2017 Nov 8;19(43):29106-29113. doi: 10.1039/c7cp06171d.
MXenes are attracting much attention as electrode materials due to their excellent energy storage properties and good electrical conductivity. Here a carbonized derivative of TiC (one representative MXene material), a TiC monolayer, is designed. Density functional theory (DFT) calculations were performed to investigate the geometric and electronic properties, dynamic stability, and Li/Na storage capability of TiC. The TiC monolayer is proved to be a structurally stable material showing the nature of the metal with C dimers rather than the individual C atom. Moreover, the TiC monolayer exhibits a low diffusion barrier and high storage capacity (up to TiCNa stoichiometry) in Na ion batteries (NIBs) compared with Li ion batteries (LIBs). Its superior properties, such as good electronic conductivity, fast Na diffusion, low open circuit voltage (OCV), and high theoretical Na storage capacity, make the TiC monolayer a promising anode material for NIBs. More importantly, similar to MXene TiC, new MC monolayers with C dimers can be formed by replacing M with other transition metal elements, and the properties of these monolayers are worthy of further study.
MXenes因其优异的储能性能和良好的导电性作为电极材料备受关注。在此，设计了一种TiC（一种典型的MXene材料）的碳化衍生物——TiC单层。进行了密度泛函理论（DFT）计算，以研究TiC的几何和电子性质、动态稳定性以及锂/钠存储能力。TiC单层被证明是一种结构稳定的材料，呈现出具有C二聚体而非单个C原子的金属性质。此外，与锂离子电池（LIBs）相比，TiC单层在钠离子电池（NIBs）中表现出较低的扩散势垒和高存储容量（高达TiCNa化学计量比）。其优异的性能，如良好的电子导电性、快速的钠扩散、低开路电压（OCV）和高理论钠存储容量，使TiC单层成为一种有前景的NIBs负极材料。更重要的是，与MXene TiC类似，通过用其他过渡金属元素取代M，可以形成具有C二聚体的新型MC单层，这些单层的性质值得进一步研究。
