锌离子电池正极材料V2O5的储能机理和容量衰减原因

采用水热法结合热处理制备了具有高结晶性的V₂O₅，利用X射线衍射仪、球差校正扫描透射电子显微镜和扫描电子显微镜对V₂O₅的物相和形貌进行了表征，发现制备的V₂O₅择优取向生长并且具有良好的结晶性.电化学测试结果表明，以V₂O₅为正极材料的电池在电流密度为0.5 A/g下首次放电比容量约为340 mA·h/g.在电流密度为5 A/g下电池的首次放电比容量为170 mA·h/g，并且循环100次后衰减为50 mA·h/g.对不同放电态的V₂O₅正极材料的物相进行了分析，得出了V₂O₅正极材料在充放电过程中发生了锌离子和质子共嵌入（脱出）的反应机理；V₂O₅正极材料在充放电过程中发生的非晶化和副产物碱式硫酸锌的生成是导致以V₂O₅作为水系锌离子电池正极材料的电池系统发生容量衰减的主要原因.

Mechanism of Storage and Capacity Attenuation of V2O5 as Cathode of Zinc-ion Battery

In this paper, the vanadium(V₂O₅) was prepared by hydrothermal and then heat treatments and characterized by X-ray diffraction(XRD), spherical aberration corrected scanning transmission electron microscopy(STEM) and scanning electron microscopy(SEM). The results show that the prepared V₂O₅ grew preferentially and had good crystallinity. The V₂O₅ cathode material had a specific capacity of 340 mA·h/g at initial discharge at constant current of 0.5 A/g. The initial capacity of the battery was 170 mA·h/g at a constant discharge-charge current density of 5 A/g, which gradually decayed to 50 mA·h/g after 100 cycles. By subsequent analysis of the phase evolution of V₂O₅ cathode materials at different discharge states using XRD and STEM, it was revealed that the co-insertion(extraction) of zinc-ions and protons occured during the discharge-charge processes, and the amorphization of the positive electrode material during discharge-charge and the formation of by-product basic zinc sulfate lead to capacity attenuation of the battery system.