Preparation and Electrochemical Properties of Li3V2(PO4)3−xBrx/Carbon Composites as Cathode Materials for Lithium-Ion Batteries

• Published in: Nanomaterials (Basel, Switzerland) Vol. 7; no. 3; p. 52
• Main Authors: Cao, Xiaoyu, Mo, Lulu, Zhu, Limin, Xie, Lingling
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 24.02.2017; MDPI
• Subjects: bromine ion doping; Carbon; Carbon cycle; cathode materials; Cathodes; Charge transfer; Crystal structure; Crystallization; Cycles; Discharge; Electrochemical analysis; Electrochemical impedance spectroscopy; Electrochemistry; Electrode materials; Electron microscopy; enhanced electrochemical performances; Irregular particles; Li3V2(PO4)3/carbon composites; Lithium; Lithium-ion batteries; Particulate composites; Rechargeable batteries; Rheological properties; Scanning electron microscopy; Solid solutions; Spectroscopy; X-ray diffraction
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano7030052

Li3V2(PO4)3−xBrx/carbon (x = 0.08, 0.14, 0.20, and 0.26) composites as cathode materials for lithium-ion batteries were prepared through partially substituting PO43− with Br−, via a rheological phase reaction method. The crystal structure and morphology of the as-prepared composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and electrochemical properties were evaluated by charge/discharge cycling and electrochemical impedance spectroscopy (EIS). XRD results reveal that the Li3V2(PO4)3−xBrx/carbon composites with solid solution phase are well crystallized and have the same monoclinic structure as the pristine Li3V2(PO4)3/carbon composite. It is indicated by SEM images that the Li3V2(PO4)3−xBrx/carbon composites possess large and irregular particles, with an increasing Br− content. Among the Li3V2(PO4)3−xBrx/carbon composites, the Li3V2(PO4)2.86Br0.14/carbon composite shows the highest initial discharge capacity of 178.33 mAh•g−1 at the current rate of 30 mA•g−1 in the voltage range of 4.8-3.0 V, and the discharge capacity of 139.66 mAh•g−1 remains after 100 charge/discharge cycles. Even if operated at the current rate of 90 mA•g−1, Li3V2(PO4)2.86Br0.14/carbon composite still releases the initial discharge capacity of 156.57 mAh•g−1, and the discharge capacity of 123.3 mAh•g−1 can be maintained after the same number of cycles, which is beyond the discharge capacity and cycleability of the pristine Li3V2(PO4)3/carbon composite. EIS results imply that the Li3V2(PO4)2.86Br0.14/carbon composite demonstrates a decreased charge transfer resistance and preserves a good interfacial compatibility between solid electrode and electrolyte solution, compared with the pristine Li3V2(PO4)3/carbon composite upon cycling.