磷酸锰铁锂正极材料的第一性原理研究  

First principles study of LiMn1−xFexPO4 cathode materials

作　　者：曹春晖 唐火强 郑保平 胡来文 章志珍 王国庆 CAO Chunhui;TANG Huoqiang;ZHENG Baoping;HU Laiwen;ZHANG Zhizhen;WANG Guoqing(Dongguan Dongyangguang Technology R&D Co.,Dongguan 523870,China;School of Materials,Sun Yat-Sen University,Guangzhou 510275,China;The 5th Electronics Research Institute,Ministry of Industry and Information Technology,Guangzhou 511370,China)

机构地区：[1]东莞东阳光科研发有限公司,东莞523870 [2]中山大学材料学院,广州510275 [3]工业和信息化部电子第五研究所,广州511370

出　　处：《中国有色金属学报》2025年第3期881-890,共10页The Chinese Journal of Nonferrous Metals

基　　金：广东省重点领域研发计划资助项目(2023B0909060004)。

摘　　要：磷酸锰铁锂(LiMn_(1-x)Fe_(x)PO_(4), LMFP)具有高能量密度、低成本、高安全等优势,是新一代锂电正极材料。目前LMFP处于产业化前夕,其面临的主要问题包括电子电导率偏低、倍率性能不足以及对高温的敏感性等问题,铁掺杂量(x,摩尔分数)的优化对于改善以上问题至关重要。但是常规实验方法对铁掺杂量的研究受限于实际条件,很难准确调控单因素变量,导致研究结果通常重复性差,无法确定最佳的铁掺杂量。本文从第一性原理出发,通过对原子结构的密度泛函理论DFT计算,得到不同铁掺杂量下LMFP的晶格常数、形成能、脱/嵌锂电位、扩散势垒和能带结构等参数,方法可靠。通过对以上参数的对比分析,确定了最佳铁掺杂量范围。结果表明:最佳铁掺杂量x取值范围在0.2~0.4之间,此时LMFP的结构稳定性最好,同时又可以保持较高的能量密度。磷酸铁锂(LiFePO_(4), LFP)和LMFP不易形成完全固溶体;LFP的扩散势垒最低,为0.506 eV,说明在LFP中掺杂锰增加了锂离子的扩散难度。同时计算得到的结构参数也为LMFP后续的实验研究提供了有力的微观结构理论依据。Lithium manganese-iron phosphate(LiMn_(1-x)Fe_(x)PO_(4),LMFP),with the advantages of high energy density,low cost and high safety,is a new-generation cathode material for lithium-ion batteries.Currently,on the verge of industrialization,LMFP faces main problems such as low electronic conductivity,insufficient rate performance and high-temperature sensitivity.Optimizing the Mn/Fe ratio is crucial for improving these issues.However,conventional experimental methods for studying the Mn/Fe ratio are limited by practical conditions.It is difficult to accurately control single-factor variables,resulting in poor repeatability of results and inability to determine the optimal Mn/Fe ratio.In this study,based on the Ab-initio method,Density Functional Theory(DFT)calculations on the atomic structure were conducted.Reliable parameters of LMFP under different Mn/Fe ratios were obtained,including lattice constant,formation energy,intercalation/deintercalation potential,diffusion barrier and band structure.Through comparative analysis of these parameters,the optimal range of the Mn/Fe ratio was determined.The results show that the optimal value range of x in Mn/Fe ratio(1/x–1)is 0.2–0.4,at which LMFP has the best structural stability and can maintain a high energy density.The lithium iron phosphate(LiFePO_(4),LFP)and LMFP are not easy to form a complete solid solution.The diffusion barrier of LFP is the lowest,at 0.506 eV,indicating that doping manganese into LFP increases the difficulty of Li+diffusion.Meanwhile,the calculated structural parameters provide a strong theoretical basis for the micro-structure of subsequent experimental research on LMFP.

关 键 词：磷酸锰铁锂 正极材料 第一性原理 形成能 扩散势垒 带隙 

分 类 号：TM91[电气工程—电力电子与电力传动]