水系锌离子电池Al3 预嵌(NH4)2V10O25?8H2O正极材料的制备及其电化学性能Q

Preparation and electrochemical performance of Al3 intercalated (NH4)2V10O25?8H2O cathode for aqueous zinc ion battery

摘要:

NH4VO3为钒源、C2H2O4?2H2O为还原剂，采用水热法合成了(NH4)2V10O25?8H2O(NVO)纯相，以Al(NO3)3?9H2O为铝源对材料进行层间Al3 预嵌进行改性(Al-NVO)，通过XRD、SEM、TEM以及EDS对材料的物相和形貌进行表征。结果表明，Al3 均匀分散于材料中，Al3 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。恒流充放电，循环伏安(CV)及恒电流间歇式滴定技术(GITT)等电化学性能测试表明，Al3 预嵌能有效提高材料的容量，倍率性能及循环稳定性能。样品Al-NVO材料在0.5A/g的电流密度下首次放电比容量为329 mAh/g，经过100次循环，比容量为252mAh/g。在2.0A/g电流密度下，经过1200次循环容量仍有122.8 mAh/g，容量保持率高达 94.6%。通过不同扫速下的循环伏安及赝电容计算，层间预嵌Al3 有效提高了Zn2 的扩散动力学，改善了材料的电化学性能。

Abstract:

(NH4)2V10O25?8H2O(NVO) pure phase was synthesized by hydrothermal method with NH4VO3 as the vanadium source and C2H2O4?2H2O as the reducing agent. Al3 pre-intercalation modification Al(NO3)3?9H2O as aluminum source (Al-NVO). The phase and morphology of the material were characterized by XRD, SEM, TEM and EDS. The results show that Al3 is uniformly dispersed in the material, and the pre-embedding of Al3 changes the morphology of the material from the densely stacked sheet structure to the finer and more dispersed nanosheet structure. Electrochemical performance tests such as constant current charge and discharge, cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) showed that Al3 pre-embedding could effectively improve the capacity, rate performance and cyclic stability of the material. The initial discharge specific capacity of the sample Al-NVO material was 329 mAh/g at the current density of 0.5 A/g. After 100 cycles, the specific capacity was 252 mAh/g. At the current density of 2.0 A/g, the capacity is still 122.8 mAh/g after 1200 cycles, and the capacity retention rate is as high as 94.6 %. Through the calculation of cyclic voltammetry and pseudo capacitance at different scan rates, the interlayer pre-embedded Al3 effectively improves the diffusion kinetics of Zn2 and the electrochemical performance of the material.