LiAlO_2包覆Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5)正极材料及其电化学性能
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摘要
通过共沉淀-高温固相法合成Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5)固溶体正极材料,并通过溶液法对其进行LiAlO2包覆。采用X线衍射(XRD)、扫描电镜(SEM)、透视电镜(TEM)、电化学交流阻抗谱(EIS)和恒电流充放电测试分析样品的结构、形貌及电化学性能。研究结果表明:包覆前后样品都具备α-NaFeO2型层状结构;包覆后,Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5)的循环稳定性和倍率性能都得到显著提高。包覆量为5%(质量分数)的样品性能最优。首次放电比容量为254.64mA·h/g。50次循环后,容量保持率由84.5%提高至98.9%。当倍率为10C时,包覆样品的放电比容量可达58.29mA·h/g,而未包覆仅为15.27mA·h/g。包覆5%LiAlO2的Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5)正极材料具有最小的电荷转移阻抗。
Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) was synthesized by co-precipitation and high temperature solid state reaction, and the LiAlO_2-coated Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) was synthesized by solid-solution. The structure, surface morphology and electrochemical performance of the samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge testing. The results show that the samples deliver the α-Na Fe O2 layered structure. After coating with Li Al O2, the cyclic stability and rate capability of Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) are improved effectively. The sample coated with 5%(mass fraction) Li Al O2 exhibits excellent properties. First discharge specific capacity is 254.64 m A·h/g. The capacity retaining ratio is increased from 84.5% to 98.9% after 50 cycles. The discharge capacity of Li Al O2-coated Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) is 58.29 m A·h/g at 10 C, while that of pristine is only about 15.27 m A·h/g. The sample coated with 5%(mass fraction) Li Al O2 has the lowest charge transfer impedance.
Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) was synthesized by co-precipitation and high temperature solid state reaction, and the LiAlO_2-coated Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) was synthesized by solid-solution. The structure, surface morphology and electrochemical performance of the samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge testing. The results show that the samples deliver the α-Na Fe O2 layered structure. After coating with Li Al O2, the cyclic stability and rate capability of Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) are improved effectively. The sample coated with 5%(mass fraction) Li Al O2 exhibits excellent properties. First discharge specific capacity is 254.64 m A·h/g. The capacity retaining ratio is increased from 84.5% to 98.9% after 50 cycles. The discharge capacity of Li Al O2-coated Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5) is 58.29 m A·h/g at 10 C, while that of pristine is only about 15.27 m A·h/g. The sample coated with 5%(mass fraction) Li Al O2 has the lowest charge transfer impedance.
引文
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[2]KWON N H.The effect of carbon morphology on the Li Co O2 cathode of lithium ion batteries[J].Solid State Sciences,2013,21(7):59-65.
[3]YI Xin,WANG Xianyou,JU Bowei,et al.Effective enhancement of electrochemical performance for spherical spinel Li Mn2O4 via Li ion conductive Li2Zr O3 coating[J].Electrochimica Acta,2014,134:143-149.
[4]ZIOLKOWSKA D,KORONA K P,HAMANKIEWICZ B,et al.The role of Sn O2 surface coating on the electrochemical performance of Li Fe PO4 cathode materials[J].Electrochimica Acta,2013,108:532-539.
[5]赵煜娟,冯海兰,赵春松,等.锂离子电池富锂正极材料x Li2Mn O3·(1-x)Li MO2(M=Co,Fe,Ni1/2Mn1/2…)的研究进展[J].无机材料学报,2011,26(7):673-679.ZHAO Yujuan,FENG Hailan,ZHAO Chunsong,et al.Progress of research on the Li-rich cathode materials x Li2Mn O3·(1-x)Li MO2(M=Co,Fe,Ni1/2Mn1/2…)for Li-ion batteries[J].Journal of Inorganic Materials,2011,26(7):673-679.
[6]陈来,陈实,胡道中,等.不同组分下富锂正极材料x Li2Mn O3·(1-x)Li Ni0.5Mn0.5O2(x=0.1-0.8)的晶体结构与电化学性能[J].物理化学学报,2014,30(3):467-475.CHEN Lai,CHEN Shi,HU Daozhong,et al.Crystal structure and electrochemical performance of lithium-rich cathode materials x Li2Mn O3·(1-x)Li Ni0.5Mn0.5O2(x=0.1-0.8)[J].Acta Physico-Chimica Sinica,2014,30(3):467-475.
[7]JUNG Y S,CAVANAGH A S,YAN Y F,et al.Effects of atomic layer deposition of Al2O3 on the Li[Li0.20Mn0.54Ni0.13Co0.13]O2cathode for lithium-ion batteries[J].Journal of the Electrochemical Society,2011,158(12):A1298-A1302.
[8]杨志,李新海,王志兴,等.球形Li Ni1/3Co1/3Mn1/3O2表面非均匀成核法包覆Al2O3的研究[J].中南大学学报(自然科学版),2010,41(5):1703-1708.YANG Zhi,LI Xinhai,WANG Zhixing,et al.Surface coating of spherical Li Ni1/3Co1/3Mn1/3O2 with Al2O3 using heterogeneous nucleation process[J].Journal of Central South University(Science and Technology),2010,41(5):1703-1708.
[9]LI G R,FENG X,DING Y,et al.Al F3-coated Li(Li0.17Ni0.25Mn0.58)O2 as cathode material for Li-ion batteries[J].Electrochimica Acta,2012,78:308-315.
[10]WANG Zhiyuan,LIU Enzuo,GUO Lichao,et al.Cycle performance improvement of Li-rich layered cathode material Li[Li0.2Mn0.54Ni0.13Co0.13]O2 by Zr O2 coating[J].Surface and Coatings Technology,2013,235:570-576.
[11]MA Xiaoling,WANG Chiwei,HAN Xiaoyan,et al.Effect of Al PO4 coating on the electrochemical properties of Li Ni0.8Co0.2O2 cathode material[J].Journal of Alloys and Compounds,2008,453(1/2):352-355.
[12]CHEN Yanping,ZHANG Yun,CHEN Baojun,et al.An approach to application for Li Ni0.6Co0.2Mn0.2O2 cathode material at high cutoff voltage by Ti O2 coating[J].Journal of Power Sources,2014,256:20-27.
[13]KONG J Z.REN C,TAI G A,et al.Ultrathin Zn O coating for improved electrochemical performance of Li Ni0.5Co0.2Mn0.3O2 cathode material[J].Journal of Power Sources,2014,266:433-439.
[14]LIU Dongqiang,YU Ji,SUN Yuheng,et al.Enhancement of electrochemical performance of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 by surface modification with Li4Ti5O12[J].Electrochimica Acta,2014,115:399-406.
[15]OKADA K,MACHIDA N,NAITO M,et al.Preparation and electrochemical properties of Li Al O2-coated Li(Ni1/3Mn1/3Co1/3)O2for all-solid-state batteries[J].Solid State Ionics,2014,255:120-127.
[16]LIU Yunjian,GAO Yanyong,DOU Aichun.Influence of Li content on the structure and electrochemical performance of Li1+xNi0.25Mn0.75O2.25+x/2 cathode for Li-ion battery[J].Journal of Power Sources,2014,248:679-684.
[17]FU Fang,HUANG Yiyin,WU Peng,et al.Controlled synthesis of lithium-rich layered Li1.2Mn0.56Ni0.12Co0.12O2 oxide with tunable morphology and structure as cathode material for lithium-ion batteries by solvo/hydrothermal methods[J].Journal of Alloys and Compounds,2014,618:673-678.
[18]PARK S H,KANG S H,JOHNSON C S,et al.Lithium–manganese–nickel-oxide electrodes with integrated layered–spinel structures for lithium batteries[J].Electrochemistry Communications,2007,56(9):262-268.
[19]刘云建,王亚平,刘三兵,等.Li Ni0.2Li0.2Mn0.6O2正极材料的合成与碳包覆[J].中南大学学报(自然科学版),2013,44(2):482-486.LIU Yunjian,WANG Yaping,LIU Sanbing,et al.Synthesized and carbon-coating of Li Ni0.2Li0.2Mn0.6O2 cathodes[J].Journal of Central South University(Science and Technology),2013,44(2):482-486.
[20]YI Tingfeng,SHU Jie,ZHU Yanrong,et al.Structure and electrochemical performance of Li4Ti5O12-coated Li Mn1.4Ni0.4Cr0.2O4 spinel as 5 V materials[J].Electrochemistry Communications,2009,11:91-94.
[21]SHU Hongbo,CHEN Manfang,FU Yanqing,et al.Improvement of electrochemical performance for spherical Li Fe PO4 via hybrid coated with electron conductive carbon and fast Li ion conductive La0.56Li0.33Ti O3[J].Journal of Power Sources,2014,252:73-78.
[22]LIU Yunjian,LIU Sanbing,WANG Yaping,et al.Effect of Mn O2modification on electrochemical performance of Li Ni0.2Li0.2Mn0.6O2 layered solid solution cathode[J].Journal of Power Sources,2013,222:455-460.