双金属预插层钒基材料在锌离子电池中的电化学行为研究

Electrochemical behavior of bimetallic pre-inserted vanadium-based materials in zinc ion batteries

在锌离子正极材料中,钒基化合物因其成本低、理论容量高而被广泛研究。通过简单水热法合成得到双金属预插层钒基正极。采用XRD、EDS、ICP和TGA等方法,确定了材料的化学式为Na_(0.24)Zn_(0.02)V_(2)O_(5)·1.2H_(2)O(NZVO)。使用3 mol/L Zn(CF_(3)SO_(3))_(2)为电解液,锌片为负极,组装纽扣电池(NZVO‖Zn),使用循环伏安曲线(CV)、电化学阻抗谱(EIS)恒流充放电和倍率对其电化学行为进行分析。在5 A/g电流密度下,经过2000圈循环后比容量可达到102.8 mAh/g,且容量不衰减。通过非原位XRD(Ex-situ XRD)对不同电压下的NZVO进行测试,探究NZVO的储锌机理,并深入研究了赝电容行为对NZVO‖Zn电池性能的影响。研究结果表明,NZVO‖Zn表现出了良好的电化学性能,作为一种高性能的锌离子正极具有广阔的应用前景。

Among zinc ion cathode materials,low cost and high theoretical capacity in vanadium-based compounds have been extensively investigated.The bimetallic pre-inserted vanadium-based cathode was obtained by the simple hydrothermal method.The chemical formula of the material was determined to be Na_(0.24)Zn_(0.02)V_(2)O_(5)·1.2H_(2)O by utilizing XRD,EDS,ICP and TGA.The cells(NZVO‖Zn)were assembled using 3 mol/L Zn(CF_(3)SO_(3))2 as the electrolyte and zinc flakes as the cathode electrode,and their electrochemical behavior was analyzed through cyclic voltammetric curves(CV),electrochemical impedance spectroscopy(EIS)with constant current charge-discharge and rate performance.At the current density of 5 A/g,the capacity can reach 102.8 mAh/g after 2000 cycles with no capacity decay.The NZVO was tested by ex-situ XRD at different voltages to investigate the zinc storage mechanism of NZVO,and the effect of pseudo-capacitive behavior on the performance of NZVO‖Zn cells was investigated in detail.The results indicate that NZVO‖Zn exhibits good electrochemical performance and has potential as high performance zinc ion cathode.