锂电池正极材料LiFePO_4的电子结构和晶形模拟研究  

Theoretical study of the electronic structure and crystal morphology of LiFePO_4 as cathode material for lithium battery

作　　者：黄辉胜[1,2] 胡武洪[1,2] 张国庆[1,2] 张福兰[1,2] 丁世敏[1,2] 

机构地区：[1]重庆市无机特种功能材料重点实验室,重庆408100 [2]长江师范学院化学化工学院,重庆408100

出　　处：《原子与分子物理学报》2015年第5期870-874,共5页Journal of Atomic and Molecular Physics

基　　金：重庆市自然科学基金(cstc2011jj A50013);重庆市教委科技计划项目(KJ111310)

摘　　要：分别运用Materials Studio软件的CASTEP和Morphology模块对磷酸铁锂(LiFePO4)的结构和晶形进行计算模拟研究,获得其优化构型、电子结构、晶体形貌、晶面面积和晶面相对生长速率等特征参数.研究结果表明,PBE方法的计算精度明显高于CA-PZ方法,化合物中的Fe—O配位键本质上是共价键.LiFePO4的理论模拟晶形为柱状晶体,与其块状的实测晶体形貌存在较大差异,这归因于理论模拟晶形是LiFePO4在真空中的生长晶习,而非真实环境下的晶习.在LiFePO4的实际晶形中,(020)晶面拥有较大的面积,这与该晶面的原子排列方式和原子占有率密切相关.此外,表面活性剂和LiFePO4各特征晶面之间可形成大量C—H…O氢键,将晶粒有效地包覆起来,降低其生长速率,从而抑制LiFePO4晶粒长大.The geometric and electronic structures, crystal morphology, crystal facet area and the crystal facet relative growing velocity of LiFePO4 were theoretically investigated by the CASTEP and Morphology modules. The obtained results show that the PBE functional has better accuracy than CA - PZ functional. The Fe--O coordination bonds are covalent in nature. Moreover, the simulated crystal morphology is columnar, which is obviously different from the experimental crystal morphology of flake. This is due to the calculated crystal morphology is the crystal habit of LiFePO4 under the vacuum condition, not in the actual environment. For the experimental mor- phology of LiFePO4, the area of the （O2O） crystal facet is large, which is closely related with the atomic ar- rangement and density on the crystal surface. Additionally, there are many C--H…O hydrogen bonds between surfactant and crystal facets of LiFePO4, the crystallites are coated and their growing velocities slow down, and so the surfactant can control crystallite growth.

关 键 词：LIFEPO4 电子结构 晶形 溶剂效应 表面活性剂 

分 类 号：O641[理学—物理化学]