中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 27 No. 2 February 2017 |
（1. College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454000, China;
2. National Center for Quality National Center for Quality Supervision and Inspection of Building Decoration Materials, Zhengzhou 450004, China）
Abstract:Vanadium (III) phosphate monoclinic VPO4·H2O was synthesized hydrothermally. The ε-VOPO4 nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO4·H2O, can reversibly react with more than 1 mol lithium atoms in two steps. Crystal XRD analysis revealed that the structure of the ε-VOPO4 nanosheets is monoclinic with lattice parameters of α=7.2588(4) ？, b=6.8633(2) ？ and c=7.2667(4) ？. The results show that the ε-VOPO4 nanosheets have a thickness of 200 nm and uniform crystallinity. Electrochemical characterization of the ε-VOPO4 monoclinic nanosheets reveals that they have good electrochemical properties at high current density, and deliver high initial capacity of 230.3 mA·h/g at a current density of 0.09 mA/cm2. Following the first charge cycle, reversible electrochemical lithium extraction/insertion at current density of 0.6 mA/cm2 affords a capacity retention rate of 73.6% (2.0-4.3 V window) that is stable for at least 1000 cycles.
Key words: lithium-ion battery; nanosheet; vanadium phosphate; cathode material; synthesis; characterization
