摘要
磷酸锰铁锂(LiFe_(x)Mn_(1−x)PO_(4),LFMP)因其低成本和安全优势,兼具LiFePO_(4)的良好的循环性能和LiMnPO_(4)的高能量密度,正逐渐成为一种安全可靠的商业化锂离子电池存储材料。然而,LFMP中较严重的晶格应力及充电时Mn3+引起的Jahn-Teller畸变导致了其较低的锂离子扩散速率以及电导率,限制了其进一步的工业应用。针对这一问题,本研究采用球磨辅助固相烧结的方法制备了Ce掺杂的LiFe_(0.6)Mn_(0.4)PO_(4)/C(LFMP/C-Ce),并分析了不同掺杂含量下材料的电化学性能。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术表征了这些材料的成分、表面形貌和微观形貌,这些分析证实了Ce离子成功掺杂到橄榄石晶格过渡金属(Mn)的位点当中,减少了晶格应力,延长了Li—O键,同时缩短了Mn—O键,从而缓解了Jahn-Teller畸变。使用恒流恒压充放电测试、恒电流间歇滴定(GITT)、循环伏安法(CV)和电化学阻抗谱(EIS)等技术评估了样品的电化学性能。结果表明,掺杂1%Ce(LFMP/C-Ce1%)可获得最佳的循环性能。LFMP/C-Ce1%在1 C下经过500次循环后表现出92.6%的容量保持率。电感耦合等离子体发射光谱(ICP-OES)分析证实,该掺杂水平可有效抑制循环后Mn金属溶解,从而提高LFMP正极材料的电化学性能和稳定性。
LiFe_(x)Mn_(1−x)PO_(4)(LFMP)is emerging as a safe and cost-effective cathode material for lithium-ion batteries,combining the excellent cycling stability of LiFePO_(4) with the high energy density of LiMnPO_(4).However,severe lattice stress and Jahn-Teller distortion from Mn3+during charging reduce lithium-ion diffusion and electrical conductivity,limiting its industrial application.To address these challenges,Ce-doped LiFe_(0.6)Mn_(0.4)PO_(4)/C(LFMP/C-Ce)was synthesized via ball milling-assisted solid-state sintering,and the effect of varying Ce doping levels on electrochemical performance was investigated.X-ray diffraction,scanning electron microscopy,and transmission electron microscopy were employed to characterize the material composition,surface morphology,and microstructure.The analyses confirmed successful incorporation of Ce ions into the olivine lattice,which alleviated lattice stress by elongating Li-O bonds and shortening Mn-O bonds,thereby mitigating Jahn-Teller distortion.Electrochemical performance was evaluated using constant current-constant voltage charge discharge testing,galvanostatic intermittent titration technique,cyclic voltammetry,and electrochemical impedance spectroscopy.The results indicated that 1%Ce doping(LFMP/C-Ce1%)delivered the best cycling performance,retaining 92.6%of its capacity after 500 cycles at 1 C.Inductively coupled plasma optical emission spectrometry confirmed that this doping level effectively suppresses Mn dissolution during cycling,thereby enhancing the electrochemical stability and performance of the LFMP cathode.
作者
赵万炜
杨亚东
靳光耀
梁闻予
李建强
徐睿
ZHAO Wanwei;YANG Yadong;JIN Guangyao;LIANG Wenyu;LI Jianqiang;XU Rui(Department of Materials Science and Technology,University of Science and Technology Beijing,Beijing 100083,China)
出处
《储能科学与技术》
北大核心
2025年第12期4412-4420,共9页
Energy Storage Science and Technology
基金
中央高校基本科研业务费(FRF-TP-24-001A)。
关键词
锂离子电池
磷酸锰铁锂
过渡金属溶解
阳离子掺杂
lithium-ion battery
lithium iron manganese phosphate
transition metal dissolution
cation doping
