Al^(3+)预嵌(NH_(4))_(2)V_(10)O_(25)·8H_(2)O正极材料在水系锌离子电池的应用

Application of Al intercalated(NH_(4))2V_(10)O_(25)·8H_(2)O cathode material in aqueous zinc ion battery

以NH_(4)VO_(3)为钒源、二水合草酸(C_(2)H_(2)O_(4)·2H_(2)O)为还原剂,采用水热法合成了(NH_(4))_(2)V_(10)O_(25)·8H_(2)O(NVO)纯相,以Al(NO_(3))_(3)·9H_(2)O为铝源对材料进行层间Al^(3+)预嵌改性得到Al^(3+)预嵌的(NH_(4))_(2)V_(10)O_(25)·8H_(2)O(Al-6NVO)材料,通过XRD、SEM、TEM以及EDS对材料进行了表征,采用恒流充放电、循环伏安及恒电流间歇式滴定技术对其电化学性能进行了测试。结果表明,Al^(3+)均匀分散于材料中,Al^(3+)预嵌使材料形貌由密集堆叠的片状结构向更细小更分散的纳米片状结构转变。Al^(3+)预嵌能有效提高材料的比容量、倍率性能及循环稳定性能。Al-6NVO在0.5 A/g电流密度下首次放电比容量为329 m A·h/g,经过100次循环,比容量为252 m A·h/g。在2.0 A/g电流密度下,经过1200次循环容量仍可达122.8 m A·h/g,容量保持率高达94.6%。通过不同扫描速率下的循环伏安及赝电容计算,层间预嵌Al^(3+)有效提高了Zn^(2+)的扩散动力学,改善了材料的电化学性能。

Pure phase(NH_(4))2V_(10)O_(25)·8H_(2)O(NVO)was synthesized by hydrothermal method with NH_(4)VO_(3) as vanadium source and C_(2)H_(2)O_(4)·2H_(2)O as reducing agent.(NH_(4))_(2)V_(10)O_(25)·8H_(2)O(Al-6NVO)material was prepared by interlaminar Al^(3+)pre-embedding with Al(NO_(3))_(3)·9H_(2)O as aluminum source.The materials were characterized by XRD,SEM,TEM and EDS.The electrochemical properties were tested by constant current charge and discharge,cyclic voltammetry and galvanostatic intermittent titration technique.The results showed that Al^(3+)was uniformly dispersed in the material,and the pre-embedding of Al^(3+)changed the morphology of the material from the densely stacked sheet structure to the finer and more dispersed nanosheet structure.Al^(3+)pre-embedding could effectively improve the capacity,rate performance and cyclic stability of the material.The initial discharge specific capacity of Al-6NVO material was 329 m A·h/g at a current density of 0.5 A/g.After 100 cycles,the specific capacity was 252 m A·h/g.At 2.0 A/g,the specific capacity was still 122.8 m A·h/g after 1200 cycles,and the capacity retention rate was as high as94.6%.Through the calculation of cyclic voltammetry and pseudo capacitance at different scan rates,the interlayer Al^(3+)pre-embedding effectively improved the diffusion kinetics of Zn^(2+)and the electrochemical performance of the material.