School of Mechanical and Electrical Engineering, Xi'an University of Architecture & Technology, Xi'an, 710055, China.
School of Mechanical and Electrical Engineering, Xi'an University of Architecture & Technology, Xi'an, 710055, China.
J Mol Graph Model. 2023 Dec;125:108604. doi: 10.1016/j.jmgm.2023.108604. Epub 2023 Aug 16.
In this study, the thermodynamic stability, embedding voltage, volume change rate, electronic structure properties, mechanical properties and lithium-ion diffusion characteristics of the Mn, N co-doped LiFePO material are investigated using a first-principles approach based on density generalization theory. The results show that the doped system has a low formation energy and the material meets the thermodynamic stability criteria. During the de-lithium process, the volume change rate of the doped material decreases and the cycling performance is improved, but the battery energy density decreases slightly. It is also found that the doping of N led to the transformation of the material from a p-type semiconductor to an N-type semiconductor, while the doping of Mn and N lead to the creation of impurity bands, narrowing of the band gap and an increase in conductivity. At the same time, Mn, N co-doping greatly improve the ductility of the material, suppress the generation of microcracks, and reduce the possibility of shear deformation. In addition, it is noteworthy that the lithium-ion diffusion energy barrier of the doped system is reduced, which predicts an increase in the diffusion rate of lithium ions in the doped system.
本研究采用基于密度泛函理论的第一性原理方法，研究了 Mn、N 共掺杂 LiFePO 材料的热力学稳定性、嵌入电压、体积变化率、电子结构性质、力学性能和锂离子扩散特性。结果表明，掺杂体系具有较低的形成能，满足热力学稳定性判据。在脱锂过程中，掺杂材料的体积变化率减小，循环性能得到改善，但电池能量密度略有降低。还发现，N 的掺杂导致材料从 p 型半导体转变为 n 型半导体，而 Mn 和 N 的掺杂导致杂质带的形成、带隙变窄和电导率增加。同时，Mn、N 共掺杂极大地提高了材料的延展性，抑制了微裂纹的产生，降低了剪切变形的可能性。此外，值得注意的是，掺杂体系的锂离子扩散能垒降低，预示着掺杂体系中锂离子的扩散速率增加。
