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 

机构地区：[1]State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal,Department of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China

出　　处：《Rare Metals》2021年第12期3512-3519,共8页稀有金属（英文版）

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)。

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.

关 键 词：Energy storage materials First principles Battery cathode LiFePO_(4) Doping Electronic properties 

分 类 号：TQ131.11[化学工程—无机化工] TM912[电气工程—电力电子与电力传动]