摘要
磷酸锰铁锂(LiMn_(1-x)Fe_(x)PO_(4),0<x≤0.5)兼具LiFePO_(4)结构稳定性好和LiMnPO4工作电压高(4.10 V(vs.Li/Li^(+)))的优点,其能量密度相较于LiFePO_(4)可提升15%∼20%,是一种极具产业化应用前景的锂离子电池(LIBs)正极材料。然而,该材料的电化学性能受到了其离子/电子传输能力弱和晶体结构稳定性不足等问题的严重限制,难以满足产业化应用需求。总结了LiMn_(1-x)Fe_(x)PO_(4)正极材料近年来的研究进展,从晶体结构、储锂机制、制备方法和性能提升策略等方面进行了系统阐述和深入分析。在此基础之上,对LiMn_(1-x)Fe_(x)PO_(4)正极材料的产业化发展路径进行了总结与展望,对LiMn_(1-x)Fe_(x)PO_(4)正极材料电化学储锂机制、制备方法与性能提升策略的深入分析,可为该材料的基础研究和产业开发提供重要理论指导。
Lithium-ion batteries(LIBs)have become an important part of the energy storage system and an indispensable key link in the development of new energy storage technology,owing to their advantages of high energy density,low self-discharge,light weight and low pollution.With the rapid development of the new energy vehicles,the performance of LIBs as power batteries is required to be further improved.The cathode material is one of the most important part of LIBs,and its properties have an important impact on the overall performance of the batteries.Therefore,the design and preparation of advanced cathode materials have received extensive attention from academic and industrial research around the world.The LiFePO_(4) cathode material is commercially available due to its abundant raw materials,good cycling performance and low toxicity,but its low energy density can no longer meet the quickly growing energy demands of new energy industry.For the past few years,solid-solution lithium manganese iron phosphate(LiMn_(1-x)Fe_(x)PO_(4),0<x≤0.5)cathode materials have received more and more attention.Owing to the replacement of Fe^(2+)to Mn^(2+),LiMn_(1-x)Fe_(x)PO_(4) can integrate the advantages of good structural stability and high operating voltage,and their energy densities can be increased by 15%~20%compared with LiFePO_(4).Nevertheless,these materials still have problems such as weak ion/electron transport properties and insufficient crystal structure stability.This paper comprehensively summarized the research progress of LiMn_(1-x)Fe_(x)PO_(4) cathode materials in recent years.Firstly,the crystal structure characteristics of the materials were introduced.Due to the olivine crystal structure with Pnma space group,P and O form a high-strength P-O covalent bond,which made it difficult for O to escape from the crystal structure,thus the materials had relatively high safety performance.Whereas,Li+could only diffuse along the[010]direction,owing to the lack of continuous MnO_(6)(FeO_(6))co-angular octahedral network in the crystal structure of these materials.Therefore,the Li+and electron transport properties of LiMn_(1-x)Fe_(x)PO_(4) cathode materials were very poor,which seriously limited the improvement of their electrochemical performance.Meanwhile,the electrochemical lithium storage mechanism of LiMn_(1-x)Fe_(x)PO_(4) cathode materials was discussed.At present,the lithium storage mechanism of LiMn_(1-x)Fe_(x)PO_(4) was still controversial,and researchers generally agreed with the two charge and discharge models of‘radial model’and‘mosaic model’.Secondly,the preparation methods of LiMn_(1-x)Fe_(x)PO_(4) cathode materials as well as their advantages and disadvantages were systematically expounded.In detail,the preparation methods were mainly divided into liquid phase methods and solid phase methods.The liquid phase methods could effectively control the composition,morphology and size of the products,and had the advantages of simple equipment and low reaction energy consumption,but they also had the disadvantages of difficult control of the synthesis process and relatively high production cost.The solid phase methods were simple in process,controllable in particle size,and convenient for mass production.However,they must rely on mechanical crushing and mixing,and the ingredients were not easy to control accurately,thus inevitably leading to the phenomenon of uneven mixing.Thirdly,the performance improvement strategies of LiMn_(1-x)Fe_(x)PO_(4) cathode materials were discussed in detail,including morphology structure control,particle size optimization,surface coating,and ion doping.The optimization of the morphology structure and particle size could effectively increase the specific surface area to make fully contact of the electrode materials with the electrolyte and improve the reaction kinetics of the electrode materials.The surface coating could effectively enhance the conductivity of LiMn_(1-x)Fe_(x)PO_(4) cathode materials and inhibit the dissolution of Mn,thereby improving the electrochemical performance.Besides,ion doping could cause defects in the lattice of the material,and the existence of defects could expand the diffusion channel of Li+and reduce the energy barrier of electron transfer,thus fundamentally facilitating the ion/electron conductivity of the materials.Finally,the industrial development paths of LiMn_(1-x)Fe_(x)PO_(4) cathode materials were summarized and prospected.It was necessary to further explore the electrochemical lithium storage mechanism,thus providing important theoretical guidance for the structural design and performance improvement of the materials.Various performance improvement strategies including morphology structure and particle size optimization,surface coating,and ion doping should be devoted to synergistically improve the ionic/electronic conductivity and crystal structure stability of LiMn_(1-x)Fe_(x)PO_(4) cathode materials.Importantly,the mass production technologies should be further developed for the large-scale production of LiMn_(1-x)Fe_(x)PO_(4) cathode materials.The electrochemical lithium storage mechanism,preparation methods and performance improvement strategies of LiMn_(1-x)Fe_(x)PO_(4) cathode material were deeply analyzed,which could provide important theoretical guidance for the basic research and industrial development of the materials.
作者
詹皓博
刘世琦
王勤
曹名磊
马亚楠
张传坤
李建
Zhan Haobo;Liu Shiqi;Wang Qin;Cao Minglei;Ma Yanan;Zhang Chuankun;Li Jian(Hubei Key Laboratory of Energy Storage and Power Battery,School of Mathematics,Physics and Optoelectronic Engineering,Hubei University of Automotive Technology,Shiyan 442002,China;Hubei Wanrun New Energy Technology Co.,Ltd.,Shiyan 442500,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2023年第12期1669-1688,共20页
Chinese Journal of Rare Metals
基金
中国博士后科学基金第71批面上基金项目(2022M712483)
汽车动力传动与电子控制湖北省重点实验室开放基金项目(ZDK1202104)
湖北汽车工业学院博士科研启动基金项目(BK201807)资助
