Synthesis characterization and improved electrochemical performance of Li2FeSiO4/C as cathode for lithium-ion battery by metal doping  

作　　者：Ling Li Enshan Han Shunpan Qiao Hui Liu Yake Shi Weiliang Yuan 

机构地区：[1]School of Chemical Engineering and Technology, Hebei University of Technology

出　　处：《Progress in Natural Science:Materials International》2019年第2期111-118,I0002,共9页自然科学进展·国际材料（英文版）

摘　　要：In this paper, Li2FeSi0.98M0.02O4/C(M = Mg, Zn, Co, Mn, Ni) was synthesized as cathode material for lithium ion battery by solid-state method. The results show that the materials doped with Mg and Zn at the Si-sites have good initial discharge capacity. Then Li2FeSi1-xMxO4/C(M = Mg, Zn;x = 0.01, 0.02, 0.03, 0.05) were also synthesized via solid-state method. It is concluded that Li2FeSi0.99Mg0.01O4/C and Li2FeSi0.98Zn0.02O4/C have better initial discharge capacity which is 125 mAh/g and 166.2 mAh/g, respectively. The capacity of Li2Fe0.98Zn0.02SiO4/C is 157.3 m Ah/g after 10 cycles at 0.1 C, and the capacity retention rate is 94.6%. The Li^+ diffusion coefficient of Li2FeSi0.98Zn0.02O4/C is higher than that of pure phase materials by one order of magnitude. The Li2FeSi0.99Mg0.01O4/C and Li2FeSi0.98Zn0.02O4/C were tested by XRD and SEM. XRD patterns indicate that the crystal structure of Li2FeSiO4 is not changed after being doped with metal ion at the Si-site. The SEM image indicates that no obvious agglomeration is detected in these materials. Li2FeSi0.98Zn0.02O4/C processes better electrochemical performance analyzed by EDS、XPS and FT-IR spectra. The data prove that Si4+ is successfully replaced by Zn^2+ in the crystal structure of Li2FeSiO4.In this paper, Li2FeSi0.98M0.02O4/C（M = Mg, Zn, Co, Mn, Ni） was synthesized as cathode material for lithium ion battery by solid-state method. The results show that the materials doped with Mg and Zn at the Si-sites have good initial discharge capacity. Then Li2FeSi1-xMxO4/C（M = Mg, Zn; x = 0.01, 0.02, 0.03, 0.05） were also synthesized via solid-state method. It is concluded that Li2FeSi0.99Mg0.01O4/C and Li2FeSi0.98Zn0.02O4/C have better initial discharge capacity which is 125 mAh/g and 166.2 mAh/g, respectively. The capacity of Li2Fe0.98Zn0.02SiO4/C is 157.3 m Ah/g after 10 cycles at 0.1 C, and the capacity retention rate is 94.6%. The Li+ diffusion coefficient of Li2FeSi0.98Zn0.02O4/C is higher than that of pure phase materials by one order of magnitude. The Li2FeSi0.99Mg0.01O4/C and Li2FeSi0.98Zn0.02O4/C were tested by XRD and SEM. XRD patterns indicate that the crystal structure of Li2FeSiO4 is not changed after being doped with metal ion at the Si-site. The SEM image indicates that no obvious agglomeration is detected in these materials. Li2FeSi0.98Zn0.02O4/C processes better electrochemical performance analyzed by EDS、XPS and FT-IR spectra. The data prove that Si4+ is successfully replaced by Zn2+ in the crystal structure of Li2FeSiO4.

关 键 词：LI2FESIO4 Mg Zn doping SOLID-STATE method LI-ION battery Electrochemical performance 

分 类 号：TM9[电气工程—电力电子与电力传动]