中文摘要：

采用基于密度泛函理论的第一性原理研究方法,计算了不同嵌锂态LixFePO4（x=0,0.75,1.0）的电子结构.对于橄榄石型LixFePO4正极材料,虽然Fe3d电子在费米能级附近相互交错,但由于受晶体场作用的限制,并不能真正成为自由电子,Fe3d电子对体系的导电性没有很大贡献,而Fe—O键在低能成键区形成p-d杂化的局域态共价键对稳定合金骨架具有重要作用.随着锂离子的脱出,体系表现出较强的共价键特征,LixFePO4中,共价键结合的强弱次序为P—O〉Fe—O〉Li—O.由弹性行为的计算结果可知,LixFePO4体系表现出脆性材料的特征,嵌锂态LixFePO4（x=1.0,0.75）比完全脱锂态的FePO4有更大的平均价键强度.

英文摘要：

Based on density functional theory of the first-principle,the electronic structures of LiFexPO4 （x = 0. 0,0. 75,1. 0） are calculated. The calculated results show that Fe3d states restrained by crystalline field cannot contribute to free electrons even though Fe3d states cross the Fermi level. Meanwhile,Fe—O bond is beneficial to stabilize the alloy structure due to the p-d hybrid orbital. With lithium ion extraction,the enhanced covalent bonds appear. In LixFePO4 system,the strength of covalent bond is in the order of P—O Fe—O Li—O. LixFePO4 system displays brittleness of material characteristic,and the LixFePO4 （ x = 1. 0,0. 75 ） with lithium intercalation have stronger average bonding strength than that of FePO4.