LiVPO4F电子结构及电化学性质的第一性原理研究

First-Principles Study of Electronic Structure and Electrochemical Property for LiVP_ _4F

采用密度泛函理论(DFT)结合投影缀加波(PAW)方法,对LiVPO4F的晶体结构,电子结构和电化学属性进行了研究。从理论上获得了脱Li前后具体的晶格参数的变化。通过对其态密度的计算,发现在放电过程中,V在化合物中呈现离子态,发生+3/+4价态的转变,电子转移主要发生在V原子上;而P原子的状态比较稳定,并不发生大的电子的转移,磷酸根的空间结构也变化不大。同时LiVPO4F的禁带宽度仅为1.63 eV,说明其在一定情况下具有良好的导电性,有利于放电过程中电子的输运。LiVPO4F是铁磁相,磁矩为2μB,而VPO4F为反铁磁相。此外,通过计算获得了LiVPO4F的平均嵌锂电压为4.0 eV。

Using the density-functional theory（DFT） combined with the projector augumented wave（PAW） method,we have investigated the crystal structure,electronic structure and electrochemical property of LiVPO4F.The change of structural parameters after the release of Li atom is obtained.Analysis of the density of states（DOS） show that V atom is ionized and its valence varies from ＋3 to ＋4 in the process of discharge.Also,the electron transfer between P and O atoms does not occur and the 3d-space structure of（PO4）3＋ keep changeless approximatively.The band gap of LiVPO4F is 1.63 eV,which means that it has good conductivity and the electron transfer is facilitated in discharge.Our results also indicate that LiVPO4F is a ferromagnetic phase and its ferromagnetic moment is 2μB,but VPO4F is a anti-ferromagnetic phase.Furthermore,it was found that the average intercalation voltage of LiVPO4F has the value of 4.0 eV.