铜掺杂五氧化二钒的制备及电化学性质

采用沉淀法于300 和600 ℃制备了结晶状的Cu0.04V2O5材料. 扫描电镜显示, 300 ℃时制备的样品具有多孔特征, 而600 ℃时制备的样品具有很高的结晶度. X射线研究表明, 少量铜掺杂不会改变V2O5的正交晶体结构. 红外光谱研究表明, 300 ℃时制备的Cu0.04V2O5样品含有少量水. 热失重分析确定了样品中所含水分是以吸附水的形式存在, 1 mol材料分子吸附水的摩尔数约为0.18 mol. 铜掺杂显著改善了V2O5的结构稳定性, 进而提高了材料的充放电循环性能. 于600 ℃制备的样品在C/5.6倍率下具有160 mAh·g-1的可逆比容量, 但提高放电倍率明显降低了材料的循环性能. 于300 ℃制备的样品在C/5.6倍率时的循环性能不如600 ℃样品, 但该材料在C/1.9倍率时仍具有100 mAh·g-1左右的可逆比容量. 两种材料在电化学性能上的差异与材料的微结构有关. 低温样品在较高放电倍率时良好的循环性能得益于其多孔的微结构, 而高温样品由于其较高的结晶度而表现出优异的低倍率充放电性能.

Preparation and Electrochemical Properties of Cu Doped V2O5

Crystalline Cu0.04V2O5 was prepared by precipitation method followed by heat treatment at 300 and 600 ℃. The material prepared at 300 ℃ showed porous morphology, whereas that prepared at 600 ℃ was highly crystalline. X-ray diffraction showed both materials exhibiting the same orthorhombic structure as that of V2O5. Fourier transform infrared spectroscopy confirmed the existence of ca 0.18 mol of absorbed water in one mol of the material prepared at 300 ℃electrochemical performance of V2O5. The material prepared at 600 ℃ had a reversible discharge capacity over 160 mAh·g-1 after 60 cycles at the current density of C/5.6. The material prepared at 300 ℃ showed good cycling performance at higher current densities, with a reversible capacity ca 100 mAh·g-1 when cycled at C/1.9. The discrepancy in the rate performance of Cu0.04V2O5 was attributed to the morphology of materials.