Electrochemical performance of LiVPO4F/C synthesized by different methods
(1. Shagang School of Iron and Steel, Soochow University, Suzhou 215021, China;
2. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China)
2. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China)
Abstract: LiVPO4F/C samples were synthesized by one-step solid-state reaction and two-step solid-state reaction methods, respectively. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance tests were adopted to characterize the properties of LiVPO4F/C. XRD results show that the LiVPO4F/C samples prepared by one-step solid-state reaction method have the same triclinic structure (space group as that synthesized by conventional two-step solid-state reaction. SEM image exhibits that the particle size of LiVPO4F/C prepared by one-step solid-state reaction method is smaller than that of the sample synthesized by two-step solid-state reaction. The improved electrochemical properties of the LiVPO4F/C are attributed to the depressed grain size and enhanced electrical conductivity produced via one-step solid-state reaction method using oxalic acid as both reduction agent and carbon sources. AC impedance measurements also show that the LiVPO4F/C synthesized by one-step solid-state reaction route significantly decreases the charge-transfer resistance.
Key words: lithium-ion batteries; cathode material; LiVPO4F; one-step solid-state reaction; two-step solid-state reaction