LiCoPO_4正极材料掺Zn~(2+)及全电池特性
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摘要
采用柠檬酸溶胶-凝胶法合成锌离子(Zn~(2+))掺杂的磷酸钴锂(LiCoPO_4)正极材料LiZn_xCo_(1-x)PO_4。XRD和SEM分析表明:少量Zn~(2+)掺杂不会明显改变晶格结构,且粒径变小、粒度更均一。充放电(3.0~5.1V)及高低温性能测试表明:Zn2+掺杂后,材料的比容量提高、循环性能改善,并有较好的高倍率及高低温放电性能。Zn~(2+)掺杂量为0.01时,首次0.1 C放电比容量为150.3 mAh/g,比纯相增加15%。1.0C、5.0C放电比容量分别为118.9mAh/g和67.1mAh/g。在40℃、0℃下的0.1C放电比容量分别为160.0mAh/g和37.8mAh/g。循环伏安及交流阻抗测试表明:少量Zn~(2+)掺杂使电荷转移阻抗减小,电化学可逆性增强。LiZn_(0.01)Co_(0.99)PO_4与Li_4Ti_5O_(12)组成的3.3 V全电池以0.1C放电,比容量可达135.3mAh/g。
Zinc ion( Zn~(2+)) doped lithium cobalt phosphate( LiCoPO_4) cathode materials Li Zn_xCo_(1-x)PO_4 were prepared by the citric acid-based sol-gel method.XRD and SEM analysis showed that doping a small amount of Zn~(2+) did not affected the lattice structure;the particle size was smaller and more uniform.Charge-discharge( 3.0-5.1 V) and high/low temperature performance tests showed that the specific capacity was increased and cycle performance was enhanced after Zn~(2+) doping,the material had fine high rate and high/low temperature performance.When the Zn~(2+) doping amount was 0.01,the initial specific discharge capacity of 0.1 C was 150.3 m Ah/g,which was 15% higher than that of the pure one.The specific discharge capacity of 1.0 C and 5.0 C was 118.9 m Ah/g and 67.1 m Ah/g,respectively.The specific discharge capacity of 0.1 C at 40 ℃ and 0 ℃ was 160.0 m Ah/g and 37.8 m Ah/g,respectively.The charge transfer impedance was decreased and the reversibility of lithium extraction/insertion and electrochemical reaction were improved after Zn~(2+) doping,via cyclic voltammetric and A.C.impedance spectroscopy tests.The specific capacity of 3.3 V full cell which composed of Li Zn_(0.01)Co_(0.99)PO_4 and Li_4Ti_5O_(12) was up to 135.3 mAh/g when discharged with 0.1 C.
Zinc ion( Zn~(2+)) doped lithium cobalt phosphate( LiCoPO_4) cathode materials Li Zn_xCo_(1-x)PO_4 were prepared by the citric acid-based sol-gel method.XRD and SEM analysis showed that doping a small amount of Zn~(2+) did not affected the lattice structure;the particle size was smaller and more uniform.Charge-discharge( 3.0-5.1 V) and high/low temperature performance tests showed that the specific capacity was increased and cycle performance was enhanced after Zn~(2+) doping,the material had fine high rate and high/low temperature performance.When the Zn~(2+) doping amount was 0.01,the initial specific discharge capacity of 0.1 C was 150.3 m Ah/g,which was 15% higher than that of the pure one.The specific discharge capacity of 1.0 C and 5.0 C was 118.9 m Ah/g and 67.1 m Ah/g,respectively.The specific discharge capacity of 0.1 C at 40 ℃ and 0 ℃ was 160.0 m Ah/g and 37.8 m Ah/g,respectively.The charge transfer impedance was decreased and the reversibility of lithium extraction/insertion and electrochemical reaction were improved after Zn~(2+) doping,via cyclic voltammetric and A.C.impedance spectroscopy tests.The specific capacity of 3.3 V full cell which composed of Li Zn_(0.01)Co_(0.99)PO_4 and Li_4Ti_5O_(12) was up to 135.3 mAh/g when discharged with 0.1 C.
引文
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[2]JIN B,GU H B,KIM K W.Effect of different conductive additives on charge/discharge properties of Li Co PO4/Li batteries[J].J Solid State Electrochem,2008,12(2):105-111.
[3]LI H H,JIN J,WEI J P,et al.Fast synthesis of core-shell Li CoPO4/C nanocomposite via microwave heating and its electrochemical Li intercalation performances[J].Electrochem Commun,2009,11(1):95-98.
[4]YANG L,MARKMAITREE T,LUCHT B L.Inorganic additives for passivation of high voltage cathode materials[J].J Power Sources,2011,196(4):2 251-2 254.
[5]SATYAKISHORE M V V M,VARADARAJU U V.Influence of isovalent ion substitution on the electrochemical performance of Li Co PO4[J].Mater Res Bull,2005,40(10):1 705-1 712.
[6]LI H H,WANG Y P,YANG X L,et al.Improved electrochemical performance of 5 V Li Co PO4cathode materials via yttrium doping[J].Solid State Ionics,2014,255(2):84-88.
[7]FANG H S,YI H H,HU C L,et al.Effect of Zn doping on the performance of Li Mn PO4cathode for lithium ion batteries[J].Electrochim Acta 2012,71(3):266-269.
[8]WANG Y,CHEN J,QIU J,et al.Cr-substituted Li Co PO4 core with a conductive carbon layer towards high-voltage lithium-ion batteries[J].J.Solid State Chem.2018,258:32-41.
[9]CHUNG S Y,BLOKING J T,CHIANG Y M.Electronically conductive phospho-olivines as lithium storage electrodes[J].Nat Mater,2002,1(2):123-128.