Interconnected Network of MnO2 Nanowires with a "Cocoonlike" Morphology: Redox Couple-Mediated Performance Enhancement in Symmetric Aqueous Supercapacitor
Interconnected Network of MnO2 Nanowires with a "Cocoonlike" Morphology: Redox Couple-Mediated Performance Enhancement in Symmetric Aqueous Supercapacitor
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DOI：
10.1021/am502638d
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发表时间：
2014-07-09
影响因子：
9.5
通讯作者：
Mahanty, Sourindra
中科院分区：
文献类型：
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作者：
Maiti, Sandipan;Pramanik, Atin;Mahanty, Sourindra
低电子电导率和缓慢的法拉第过程限制了MnO 2作为电化学赝电容器在循环和功率密度方面的性能。本文报道了单相α-MnO 2的制备及其在对称水性超级电容器中作为电极的应用。α-MnO 2由具有“茧状”形貌的互连纳米线网络组成。增加的“有效”表面积、微孔和中孔的共存以及这些纳米线网络中增强的电子传输导致在3 M KOH中的775 F.g（-1）的比赝电容（C-S），其源自在-1至+1 V的电势窗口中以2 mV.s（-1）的扫描速率的循环伏安法，这是双电极对称配置的最高报告。此外，将K4 Fe（CN）（6）作为氧化还原活性添加剂引入KOH导致在类似于6000 W的功率密度下能量密度增加类似于7倍。kg（-1）。Fe（CN）（6）（4-）/Fe（CN）（6）（3-）氧化还原对的存在提供了补偿缓慢法拉第反应的电子缓冲源。结果表明，这种简单的方法可能是一种有效的方法，以提高氧化还原动力学和可逆性的过渡金属氧化物为基础的赝电容器。
Low electronic conductivity and slow faradic processes limit the performance of MnO2 as an electrochemical pseudocapacitor with respect to cycling and power density. Herein, we report preparation of single-phase alpha-MnO2, composed of an interconnected nanowire network with "cocoonlike" morphology, and its application as electrode in a symmetric aqueous supercapacitor. Increased "effective" surface area, coexistence of micropores and mesopores, and enhanced electron transport in these nanowire networks result in a specific pseudocapacitance (C-S) of 775 F.g(-1) in 3 M KOH, derived from cyclic voltammetry in the potential window of -1 to +1 V at a scan rate of 2 mV.s(-1), the highest reported for two-electrode symmetric configuration. Furthermore, introduction of K4Fe(CN)(6) as a redox-active additive to KOH results in similar to 7 times increase in energy density at a power density of similar to 6000 W. kg(-1). The presence of the Fe(CN)(6)(4-)/Fe(CN)(6)(3-) redox couple provides an electron buffer source compensating for the slow faradic reactions. The results demonstrate that this simple approach might be an effective way to enhance the redox kinetics and reversibility of transition metal oxide-based pseudocapacitors.