Enhanced electrochemical properties of LiFePO4 by Mo-substitution and graphitic carbon-coating via a facile and fast microwave-assisted solid-state reaction.
A composite cathode material for lithium ion battery applications, Mo-doped LiFePO(4)/C, is obtained through a facile and fast microwave-assisted synthesis method. Rietveld analysis of LiFePO(4)-based structural models using synchrotron X-ray diffraction data shows that Mo-ions substitute onto the Fe sites and displace Fe-ions to the Li sites. Supervalent Mo(6+) doping can act to introduce Li ion vacancies due to the charge compensation effect and therefore facilitate lithium ion diffusion during charging/discharging. Transmission electron microscope images demonstrate that the pure and doped LiFePO(4) nanoparticles were uniformly covered by an approximately 5 nm thin layer of graphitic carbon. Amorphous carbon on the graphitic carbon-coated pure and doped LiFePO(4) particles forms a three-dimensional (3D) conductive carbon network, effectively improving the conductivity of these materials. The combined effects of Mo-doping and the 3D carbon network dramatically enhance the electrochemical performance of these LiFePO(4) cathodes. In particular, Mo-doped LiFePO(4)/C delivers a reversible capacity of 162 mA h g(-1) at a current of 0.5 C and shows enhanced capacity retention compared to that of undoped LiFePO(4)/C. Moreover, the electrode exhibits excellent rate capability, with an associated high discharge capacity and good electrochemical reversibility.
Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia.  zguo@uow.edu.au.
Dan
D
Li
Yudai
Y
Huang
Neeraj
N
Sharma
Zhixin
Z
Chen
Dianzeng
D
Jia
Zaiping
Z
Guo
D002244:Carbon / Q000737:chemistry*; D011211:Electric Power Supplies; D004563:Electrochemistry; D007501:Iron / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D008872:Microwaves; D008982:Molybdenum / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*
C473349:LiFePO4; D010710:Phosphates; D002244:Carbon; D008982:Molybdenum; D008094:Lithium; D007501:Iron