Fe含量对LiMn_(1-x)Fe_xPO_4固溶体电化学性能的影响
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摘要
利用溶剂热法合成Mn位Fe替代的LiMn_(1-x)Fe_xPO_4(x=0,0.3,0.5,0.7)锂离子电池正极材料。研究了LiMn_(1-x)Fe_xPO_4固溶体中Fe含量对材料晶体结构、形貌尺寸和电化学性能的影响规律。结果表明:Fe的引入对LiMnPO_4物理性能和电化学活性具有显著影响,固溶体材料比纯相LiMnPO_4具有更高的充放电容量、倍率性能和循环可逆性。其中LiMn_(0.7)Fe_(0.3)PO_4/C在5C倍率下的放电容量达到133mAh/g,为LiMnPO_4/C放电容量(83mAh/g)的1.6倍。此外,固溶体材料在常温和高温下均表现出比纯相LiMnPO_4更优异的循环稳定性,有望应用于动力锂离子电池正极材料。
The Fe substituted LiMn_(1-x)Fe_xPO_4(x=0,0.3,0.5,0.7)solid solutions were synthesized by a solvothermal method as cathode materials for lithium ion batteries.The influence of Fe content on crystal structure,morphology,particle size and electrochemical properties of LiMn_(1-x)Fe_xPO_4were investigated.The results indicate that the Fe substitution has an obvious impact on physical property and electrochemical activity of LiMnPO_4.The LiMn_(1-x)Fe_xPO_4materials have higher charge/discharge capacity,rate capability and cycling reversibility than those of pure LiMnPO_4.The discharge capacity of LiMn_(0.7)Fe_(0.3)PO_4/C at 5C is 133 m Ah/g,around 1.6 times as much as that of LiMnPO_4/C(83 m Ah/g).Furthermore,the LiMn_(1-x)Fe_xPO_4exhibits superior cycling stability than that of LiMnPO_4at 25℃and50℃,indicating a potential application as cathode material for power lithium ion batteries.
The Fe substituted LiMn_(1-x)Fe_xPO_4(x=0,0.3,0.5,0.7)solid solutions were synthesized by a solvothermal method as cathode materials for lithium ion batteries.The influence of Fe content on crystal structure,morphology,particle size and electrochemical properties of LiMn_(1-x)Fe_xPO_4were investigated.The results indicate that the Fe substitution has an obvious impact on physical property and electrochemical activity of LiMnPO_4.The LiMn_(1-x)Fe_xPO_4materials have higher charge/discharge capacity,rate capability and cycling reversibility than those of pure LiMnPO_4.The discharge capacity of LiMn_(0.7)Fe_(0.3)PO_4/C at 5C is 133 m Ah/g,around 1.6 times as much as that of LiMnPO_4/C(83 m Ah/g).Furthermore,the LiMn_(1-x)Fe_xPO_4exhibits superior cycling stability than that of LiMnPO_4at 25℃and50℃,indicating a potential application as cathode material for power lithium ion batteries.
引文
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[2]ZUO P,CHENG G,WANG L,et al.Ascorbic acidassisted solvothermal synthesis of Li M n0.9Fe0.1PO4/C nanoplatelets w ith enhanced electrochemical performance for lithium ion batteries[J].J Pow er Sources,2013,243:872-879.
[3]LIAO L,WANG H,GUO H,et al.Facile solvothermal synthesis of ultrathin Li FexMn1-xPO4nanoplates as advanced cathodes with long cycle life and superior rate capability[J].J Mater Chem A,2015,3(38):19368-19375.
[4]XIANG W,WU Z G,WANG E H,et al.Confined synthesis of graphene w rapped Li M n0.5Fe0.5PO4composite via tw o step solution phase method as high performance cathode for Li-ion batteries[J].J Pow er Sources,2016,329:94-103.
[5]KIM M S,JEGAL J P,ROH K C,et al.Synthesis of Li M n0.75Fe0.25PO4/C microspheres using a microw aveassisted process w ith a complexing agent for high-rate lithium ion batteries[J].J M ater Chem A,2014,2(27):10607-10613.
[6]DUAN J,HU G,CAO Y,et al.Synthesis of highperformance Fe-M g-Co-doped Li M n PO4/C via a mechano-chemical liquid-phase activation technique[J].Ionics,2016,22(5):609-619.
[7]MA F,ZHANG X,HE P,et al.Synthesis of hierarchical and bridging carbon-coated Li M n0.9Fe0.1PO4nanostructure as cathode material w ith improved performance for lithium ion battery[J].J Pow er Sources,2017,359:408-414.
[8]LIU S,FANG H,DAI E,et al.Effect of carbon content on properties of Li M n0.8Fe0.19M g0.01PO4/C composite cathode for lithium ion batteries[J].Electrochim Acta,2014,116:97-102.
[9]WANG Y,WANG Y,LIU X,et al.Solvothermal synthesis of Li Fe1/3M n1/3Co1/3PO4solid solution as lithium storage cathode materials[J].RSC Adv,2017,7(24):14354-14359.
[10]LI S,SU Z,JIANG X,et al.Enhanced electrochemical properties of Li Mn1-xFexPO4/C composite cathode materials prepared by sol-gel method[J].Mater Lett,2015,154(1):29-32.
[11]李威,张远杰,王选朋,等.锂离子电池正极材料Li M n0.6Fe0.4PO4/C的制备及电化学性能[J].无机材料学报,2017,32(5):476-482.
[12]ZOU B K,WANG H Y,QIANG Z Y,et al.Mixedcarbon-coated Li M n0.4Fe0.6PO4nanopow ders w ith excellent high rate and low temperature performances for lithium-ion batteries[J].Electrochim Acta,2016,196:377-385.