Zhu Zixuan, Wang Shuke
Queen Mary University of London Engineering School, Northwestern Polytechnical University Xi'an Shanxi 710072 China
School of Science, China Jiliang University Hangzhou Zhejiang 310018 China.
RSC Adv. 2023 Aug 4;13(34):23499-23504. doi: 10.1039/d3ra03446a.
Two-dimensional (2D) materials are promising anode materials for the next generation of lithium ion batteries. While the Li storage and kinetics at the surface and intercalation sites of 2D materials are widely explored, the effects of the fracture surfaces (FSs) are rarely considered despite the fact that there are numerous FSs in real 2D materials. Herein, we investigate how the FSs in graphdiyne (GDY) affect the anode performance based on first-principles calculations. Results show that both the internal and external FSs have much lower binding energies to Li atoms than perfect GDY, meaning FSs are more active in storing Li atoms. Then, the diffusion barriers of Li atoms on the internal and external FSs are only 0.42 and 0.47 eV, respectively, close to the 0.315 eV of surface sites and lower than the 0.638 eV of intercalation sites, indicating a good kinetics of Li atoms. In addition, due to the new electronic states from the C atoms with dangling bonds, the FSs convert the semiconductor characteristics of perfect GDY to metallic ones, which is helpful to the electronic conductivity. Our work demonstrates that the FSs in 2D materials are beneficial to the anode performance, which may enlighten the design of anode materials.
二维（2D）材料是下一代锂离子电池很有前景的负极材料。虽然二维材料表面和插层位点的锂存储及动力学已得到广泛研究，但尽管实际二维材料中存在大量断裂面（FSs），其影响却很少被考虑。在此，我们基于第一性原理计算研究了石墨炔（GDY）中的断裂面对负极性能的影响。结果表明，内部和外部断裂面对锂原子的结合能均远低于完美的GDY，这意味着断裂面在存储锂原子方面更具活性。然后，锂原子在内部和外部断裂面上的扩散势垒分别仅为0.42和0.47电子伏特，接近表面位点的0.315电子伏特且低于插层位点的0.638电子伏特，表明锂原子具有良好的动力学。此外，由于带有悬键的碳原子产生的新电子态，断裂面将完美GDY的半导体特性转变为金属特性，这有利于电子传导。我们的工作表明二维材料中的断裂面对负极性能有益，这可能会为负极材料的设计提供启示。
