Structure stability, electronic property and voltage profile of LiFe_(1-n)NnP_(1-m)M_(m)O_(4) olivine cathode material

作     者：Zhi-Hong Cui Xue-Feng Lu Jian-Hua Luo Xin Guo Hong-Tao Xue Fu-Ling Tang Zhi-Hong Cui;Xue-Feng Lu;Jian-Hua Luo;Xin Guo;Hong-Tao Xue;Fu-Ling Tang

作者机构：State Key Laboratory of Advanced Processing and Recycling of Non-ferrous MetalDepartment of Materials Science and EngineeringLanzhou University of TechnologyLanzhou 730050China 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2021年第40卷第12期

页      面：3512-3519页

核心收录：

学科分类：081702[工学-化学工艺] 0808[工学-电气工程] 08[工学] 0817[工学-化学工程与技术] 

基　　金：financially supported by the National Natural Science Foundation of China (No. 51662026) the Graduate Research Exploration Project and the Joint Fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals (No. 18LHPY001) 

主　　题：Energy storage materials First principles Battery cathode LiFePO_(4) Doping Electronic properties 

摘      要：First-principles computational studies under density functional theory(DFT) framework were used to investigate the structural stability, conductivity and voltage profile of LiFe_(1-n)NnP_(1-m)M_(m)O_(4)(N, M = Si or S) electrode materials. It is found that the Li FeP_(7/8)Si_(1/8)O_(4) system has the most stable structure. After doping, the band gap values of the systems decrease gradually, and LiFe_(7/8)S_(1/8)PO_(4) system has a minimum band gap of 1.553 e V, attributed to the hybridization of the Fe-d and S-p orbital electrons. The Li Fe P7/8 S1/8 O4 system demonstrates the characteristic of n-type semiconductor, and other doping systems have the feature of p-type semiconductor. Charge density difference maps show that the covalent property of Si-O bond is enhanced in the Li FeP_(7/8)Si_(1/8)O_(4) system. The average distance of Li and O atoms in the S doping systems increases from 0.21026 to 0.21486 and 0.21129 nm, respectively,indicating that doping broadens significantly the channel of Li ion de-intercalation in LiFe_(7/8)S_(1/8)PO_(4) and LiFeP_(7/8)S_(1/8)O_(4). Additionally, the results of lithium intercalation potential imply that the voltages of the doping systems fallinto the range of 2.23-2.86 V.