Hierarchical Fe3O4@Fe2O3 Core-Shell Nanorod Arrays as High-Performance Anodes for Asymmetric Supercapacitors
Hierarchical Fe3O4@Fe2O3 Core-Shell Nanorod Arrays as High-Performance Anodes for Asymmetric Supercapacitors
复制标题
分层 Fe3O4@Fe2O3 核壳纳米棒阵列作为非对称超级电容器的高性能阳极
DOI：
10.1021/acsami.5b09766
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发表时间：
2015-12-16
影响因子：
9.5
通讯作者：
Xia, Hui
中科院分区：
文献类型：
--
作者：
Tang, Xiao;Jia, Ruyue;Xia, Hui
电容相对较低的负极材料是非对称超级电容器追求高能量密度的一大挑战。赤铁矿（α - fe2o3）具有在负电位窗口（从0 V到-1 V vs Ag/AgCl）内适合可逆氧化还原反应、理论电容高、丰度丰富、无毒等特点，因此作为ASCs的负极材料受到了广泛关注。然而，Fe2O3电极不能以高速率提供大容量电容，因为其导电性差（类似于10(-14)S/cm），导致低功率密度和低能量密度。在这项工作中，提出并研究了由Fe3O4@Fe2O3核-壳纳米棒阵列（NRAs）组成的分层异质结构作为ASCs的负电极。因此，Fe3O4@Fe2O3电极与裸露的Fe2O3和Fe3O4 NRAs电极相比，表现出优越的超级电容性能，表现出大的体积电容(高达1206 F/cm(3)，质量负载为1.25 mg/cm(2))，以及良好的倍率能力和循环稳定性。采用混合电极设计制备了Fe3O4@MnO2核壳NRAs作为ASCs的正极。值得注意的是，组装后的2 V ASC器件在15.6 mW/cm(3)的功率密度下提供了0.83 mWh/cm(3)的高能量密度。这项工作首次证明了Fe3O4作为Fe2O3的导电支撑，以解决其糟糕的电子和离子传输问题。
Anode materials with relatively low capacitance remain a great challenge for asymmetric supercapacitors (ASCs) to pursue high energy density. Hematite (alpha-Fe2O3) has attracted intensive attention as anode material for ASCs, because of its suitable reversible redox reactions in a negative potential window (from 0 V to -1 V vs Ag/AgCl), high theoretical capacitance, rich abundance, and nontoxic features. Nevertheless, the Fe2O3 electrode cannot deliver large volumetric capacitance at a high rate, because of its poor electrical conductivity (similar to 10(-14) S/cm), resulting in low power density and low energy density. In this work, a hierarchical heterostructure comprising Fe3O4@Fe2O3 core-shell nanorod arrays (NRAs) is presented and investigated as the negative electrode for ASCs. Consequently, the Fe3O4@Fe2O3 electrode exhibits superior supercapacitive performance, compared to the bare Fe2O3 and Fe3O4 NRAs electrodes, demonstrating large volumetric capacitance (up to 1206 F/cm(3) with a mass loading of 1.25 mg/cm(2)), as well as good rate capability and cycling stability. The hybrid electrode design is also adopted to prepare Fe3O4@MnO2 core-shell NRAs as the positive electrode for ASCs. Significantly, the as-assembled 2 V ASC device delivered a high energy density of 0.83 mWh/cm(3) at a power density of 15.6 mW/cm(3). This work constitutes the first demonstration of Fe3O4 as the conductive supports for Fe2O3 to address the concerns about its poor electronic and ionic transport.