掺氟-富锂磷酸亚铁锂正极材料的电化学性能
|
摘要
采用固相烧结法于700℃烧结制备了具有橄榄石结构(空间群Pmnb)的微米掺氟-富锂磷酸亚铁锂。通过X粉末衍射仪、充放电循环、扫描电子显微镜、循环伏安等现代测试手段表征了制备样品的电化学性能。实验结果表明:掺氟增大了样品的晶胞。在制备的掺氟样和未掺氟富锂磷酸亚铁锂样中,在2 C倍率电流下,理论组成为Li1.15FePO4F0.15的微米样品的第1循环和第30循环的放电比容量分别为115.1 mAh/g和109.6 mAh/g。掺氟显著改善了磷酸亚铁锂的大电流放电性能,使磷酸亚铁锂的电荷传递阻抗减小。
Series of F-doped and Li-rich lithium iron phosphates with a olivine structure,composed of the micrometer size particles,were synthesized by a solid state process at 700 ℃.X-ray powder diffraction,charge-discharge cycles,cyclic voltammogram,SEM and other advanced techniques were employed to study the electrochemical performances of the as-prepared samples.The experimental results indicate that the crystal cell of the fluoride doped lithium iron phosphate are larger than that of undoped sample.The sample with a theoretical composition of Li1.15FePO4F0.15 exhibits a capacity of 115.1 mAh·g-1 in the 1st cycle and 109.6 mAh·g-1 in the 30th cycle at 2 C rate,which exhibits the best electrochemical performance in the as-synthesized fluoride doped samples and undoped sample.The fluoride doping obviously improves the discharge performance of lithium iron phosphates at high rate,and decrease the charge transfer resistance of the fluoride doped sample than those of undoped sample.
Series of F-doped and Li-rich lithium iron phosphates with a olivine structure,composed of the micrometer size particles,were synthesized by a solid state process at 700 ℃.X-ray powder diffraction,charge-discharge cycles,cyclic voltammogram,SEM and other advanced techniques were employed to study the electrochemical performances of the as-prepared samples.The experimental results indicate that the crystal cell of the fluoride doped lithium iron phosphate are larger than that of undoped sample.The sample with a theoretical composition of Li1.15FePO4F0.15 exhibits a capacity of 115.1 mAh·g-1 in the 1st cycle and 109.6 mAh·g-1 in the 30th cycle at 2 C rate,which exhibits the best electrochemical performance in the as-synthesized fluoride doped samples and undoped sample.The fluoride doping obviously improves the discharge performance of lithium iron phosphates at high rate,and decrease the charge transfer resistance of the fluoride doped sample than those of undoped sample.
引文
[1]PROSINI P P,CAREWSKA M,SCACCIA S,et al.A new syntheticroute for preparing LiFePO4 with enhanced electrochemical perfor-mance[J].J Electrochem Soc,2002,149(7):A 886-A 890.
[2]TARASOON J M,ARMAND M.Issues and challenges facing re-chargeable lithium batteries[J].Nature,2001,414:359-367.
[3]PARADA C,GIR譫N C G,FUENTES L E,et al.Synthesis and char-acterization of LiFePO4/C nanocomposites[J].Physics Procedia,2010,8:33-38.
[4]SU C,XU L H,WU B T,et al.Synthesis of spindle-shaped nano-porous C-LiFePO4composite and its application as a cathodes mate-rial in lithium ion batteries[J].Electrochimica Acta,2011,56:10204-10209.
[5]PAN M S,LIN X H,ZHOU Z T.Electrochemical performance ofLiFePO4/C doped with F synthesized by carbothermal reductionmethod using NH4F as dopant[J].J Solid State Electrochem,2012,16(4):1615-1621.
[6]王德宇.锂离子电池磷酸盐正极材料的制备与改性研究[D].北京:中科院物理所,2005.
[7]廖小珍.锂离子电池LiFePO4/C复合正极材料制备及其电化学性能研究[D].上海:上海交通大学,2005.
[8]LU F,ZHOU Y C,LIU J,et al.Enhancement of F-doping on theelectrochemical behavior of carbon-coated LiFePO4 nanoparticlesprepared by hydrothermal route[J].Electrochimica Acta,2011,56:8833-8838.
[9]张中太,罗绍华,唐子龙,等.氧位掺杂型磷酸亚铁锂粉体的制备方法:CN,200510112562.6[P].2007-08-22.
[10]ZHOU X,ZHAO X B,YU H M,et al.Electrochemical propertiesof F-doped LiFePO4/C prepared by solid-state synthesis[J].J Inor-ganic Materials,2008,23(3):587-591.
[11]李泓,黄学杰.用于二次锂电池的含氧空位的磷酸亚铁锂正极材料及其用途:CN,200410101618.3[P].2008-03-26.
[12]LU Y,GUO Z P,TONG Q S,et al.Synthesis of LiFe1-xNixPO4/Ccomposites and their electrochemical performance[J].J PowerSources,2009,194(2):786-793.
[13]张华香,童庆松,林素英,等.锂钒氧化物的合成及电化学性能的表征[J].无机盐工业,2004,36(3):26-28.
[14]DENIS Y W Y,CHRISTOPHER F,WOLFGANG W,et al.Studyof LiFePO4 by cyclic voltammetry[J].J Electrochem Soc,2007,154(4):A 253-A 257.
[15]JIN B,JIN E M,PARK K H,et al.Electrochemical properties ofLiFePO4-multiwalled carbon nanotubes composite cathode materi-als for lithium polymer battery[J].Electrochem Commun,2008,10(10):1537-1540.
[16]BIH L,ALLALI N,YACOUBI A,et al.Thermal,physical andspectroscopic investigations of P2O5-A2MoO4-A2O(A=Li,Na)glass-es[J].Physics and Chemistry of Glasses,1999,40(4):229-234.
[17]XU J W,GILSON D F R,BUTLER I S.FT-Raman and high-pres-sure FT-infrared spectroscopic investigation of monocalcium phos-phate monohydrate,Ca(H2PO4)2.H2O[J].Spectrochimica Acta,1998,54(12):1869-1878.
[18]白莹,吴锋,吴川.新型锂离子电池正极材料LiMPO4(M=Fe,Mn)的谱学和电化学研究[J].光散射学报,2004,15(4):231-237.
[2]TARASOON J M,ARMAND M.Issues and challenges facing re-chargeable lithium batteries[J].Nature,2001,414:359-367.
[3]PARADA C,GIR譫N C G,FUENTES L E,et al.Synthesis and char-acterization of LiFePO4/C nanocomposites[J].Physics Procedia,2010,8:33-38.
[4]SU C,XU L H,WU B T,et al.Synthesis of spindle-shaped nano-porous C-LiFePO4composite and its application as a cathodes mate-rial in lithium ion batteries[J].Electrochimica Acta,2011,56:10204-10209.
[5]PAN M S,LIN X H,ZHOU Z T.Electrochemical performance ofLiFePO4/C doped with F synthesized by carbothermal reductionmethod using NH4F as dopant[J].J Solid State Electrochem,2012,16(4):1615-1621.
[6]王德宇.锂离子电池磷酸盐正极材料的制备与改性研究[D].北京:中科院物理所,2005.
[7]廖小珍.锂离子电池LiFePO4/C复合正极材料制备及其电化学性能研究[D].上海:上海交通大学,2005.
[8]LU F,ZHOU Y C,LIU J,et al.Enhancement of F-doping on theelectrochemical behavior of carbon-coated LiFePO4 nanoparticlesprepared by hydrothermal route[J].Electrochimica Acta,2011,56:8833-8838.
[9]张中太,罗绍华,唐子龙,等.氧位掺杂型磷酸亚铁锂粉体的制备方法:CN,200510112562.6[P].2007-08-22.
[10]ZHOU X,ZHAO X B,YU H M,et al.Electrochemical propertiesof F-doped LiFePO4/C prepared by solid-state synthesis[J].J Inor-ganic Materials,2008,23(3):587-591.
[11]李泓,黄学杰.用于二次锂电池的含氧空位的磷酸亚铁锂正极材料及其用途:CN,200410101618.3[P].2008-03-26.
[12]LU Y,GUO Z P,TONG Q S,et al.Synthesis of LiFe1-xNixPO4/Ccomposites and their electrochemical performance[J].J PowerSources,2009,194(2):786-793.
[13]张华香,童庆松,林素英,等.锂钒氧化物的合成及电化学性能的表征[J].无机盐工业,2004,36(3):26-28.
[14]DENIS Y W Y,CHRISTOPHER F,WOLFGANG W,et al.Studyof LiFePO4 by cyclic voltammetry[J].J Electrochem Soc,2007,154(4):A 253-A 257.
[15]JIN B,JIN E M,PARK K H,et al.Electrochemical properties ofLiFePO4-multiwalled carbon nanotubes composite cathode materi-als for lithium polymer battery[J].Electrochem Commun,2008,10(10):1537-1540.
[16]BIH L,ALLALI N,YACOUBI A,et al.Thermal,physical andspectroscopic investigations of P2O5-A2MoO4-A2O(A=Li,Na)glass-es[J].Physics and Chemistry of Glasses,1999,40(4):229-234.
[17]XU J W,GILSON D F R,BUTLER I S.FT-Raman and high-pres-sure FT-infrared spectroscopic investigation of monocalcium phos-phate monohydrate,Ca(H2PO4)2.H2O[J].Spectrochimica Acta,1998,54(12):1869-1878.
[18]白莹,吴锋,吴川.新型锂离子电池正极材料LiMPO4(M=Fe,Mn)的谱学和电化学研究[J].光散射学报,2004,15(4):231-237.