尖晶石LiNi_(0.5)Mn_(1.5)O_(4)材料表面Li_(3)PO_(4)包覆改性与电化学性能  

Surface Modification and Electrochemical Performance of Spinel LiNi_(0.5)Mn_(1.5)O_(4) Cathode Material with Li3PO4 Coating

作　　者：柳娜 LIU Na(Contemporary Amperex Technology Co.,Limited.,Ningde 352106,Fujian,China)

机构地区：[1]宁德时代新能源科技股份有限公司,福建宁德352106

出　　处：《硅酸盐学报》2024年第6期2032-2039,共8页Journal of The Chinese Ceramic Society

摘　　要：尖晶石结构LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)材料因具备高工作电压、低成本和环境友好等优点,被认为是最具有发展前景的正极材料之一。然而,LNMO材料在充放电过程中表现出严重的表面失氧和Mn溶出反应,导致其整体电化学性能较差。采用前驱体Li_(3)PO_(4)包覆技术,在LNMO材料颗粒表面构建均匀的纳米包覆层,不仅提高了LNMO的循环稳定性和倍率性能,而且有效抑制了循环过程中阴极材料过渡金属溶出。结合X射线衍射仪、扫描电子显微技术、透射电子显微镜和电化学分析等测试手段,充分对比和分析Li_(3)PO_(4)包覆LNMO材料前后对微观结构和电化学性能的影响。该方法实现了Li_(3)PO_(4)的均匀包覆,并且没有改变LNMO正极材料的晶体结构。前驱体包覆3%Li_(3)PO_(4)的LNMO材料在1 C倍率下循环300圈容量保持率从无包覆的81.82%提升至包覆后的90.47%,2 C高倍率下的放电容量保持率从87.72%提升至92.39%,且EOL电芯阳极极片中过渡金属Mn溶出量明显降低。前驱体Li_(3)PO_(4)包覆策略是一种有效的材料表面改性策略,可以有效提升尖晶石型LNMO正极材料在循环过程中的结构稳定性和电化学性能。Introduction As a positive material with a low cost,a high energy density and a good power performance,spinel lithium manganese nickel oxide(LiNi_(0.5)Mn_(1.5)O_(4))has attracted much attention in the industry of lithium ion battery.Reducing the surface oxygen release behavior and the resolution of Ni or Mn during charging and discharging is a main method to improve the electrochemical performance.The conventional coating technique is to construct a coating layer on the surface of the material particles,which can isolate the electrolyte and reduce side reactions at the interface.Since the solid-phase coating method cannot form the uniform and compact coating layer,the improvement of the electrochemical performance is limited.In this paper,a precursor with Li_(3)PO_(4) layer that was produced by a wet coating method was sintered at 850℃.In addition,the impact of coating method was also analyzed by the first-principles calculation and characterizations.Methods According to a molar ratio of LiNi_(0.5)Mn_(1.5)O_(4),a certain amount of Ni_(0.25)Mn_(0.75)(OH)_(2) precursor and Li_(2)CO_(3) were weighed and mixed.The mixed material was ground in a mortar evenly.Afterwards,the ground material was sintered in a muffle furnace at 950℃for 10 h,finally obtaining a LNMO positive electrode material(i.e.,sample P0)after cooling in the furnace.According to the designed coating amount of 3%Li_(3)PO_(4),NH_(4)H_(2)PO_(4) and LiOH·H_(2)O were weighed and sequentially added to alcohol solution with LNMO particles.After stirring and evaporation,the collected products were sintered in a muffle furnace to obtain conventional coating LNMO@Li_(3)PO_(4) material(i.e.,sample P1).Also,Ni_(0.25)Mn_(0.75)(OH)_(2) precursor was mixed with deionized water in a mass ratio of 1:5.LiOH·H_(2)O was added to the coating at 3%under stirring until fully dissolved.Also,NH_(4)H_(2)PO_(4) was added in another beaker and mixed with deionized water in a mass ratio of 1:20 until fully dissolved.The above two solutions were mixed thoroughly and filtered

关 键 词：镍锰酸锂 磷酸锂 包覆 电化学性能 

分 类 号：TQ152[化学工程—电化学工业]