Abstract Core-shell architectures have stimulated growing research interest because of their optimized physical/chemical properties and potential in many energy-related applications. In this work, a facile two-step hydrothermal-annealing method was adopted to synthesize hierarchical core-shell NiCo2O4@NiMoO4 nanoarrays on nickel foam substrate, and by controlling the growth time (2h, 5h and 8h) of NiMoO4 precursor, three different morphologies and sizes of NiMoO4 nanosheets were obtained, and their morphology-dependent electrochemical performance was investigated. The results revealed that NiCo2O4@NiMoO4/NF (5h) hybrid electrode exhibits a much enhanced specific capacitance of 2806 F g-1 at 5 A g-1, nearly three times than that of pristine single-composition NiCo2O4 electrode (974 F g-1). The superior performance was attributed to the porous hierarchical structure and reasonable morphology and nanosheets thickness, which could lower electrons transfer resistance and alleviate the strain during repeated redox reactions. Furthermore, the assembled NiCo2O4@NiMoO4 (5h)//Activated carbon asymmetric supercapacitor shows a high energy density of 64.2 Wh kg-1 (750 W kg-1), and good cycling durability of 87.7% specific capacitance retention over 5000 cycles. This work provides a novel morphology-controllable approach for the synthesis of high performance core-shell electrodes for supercapacitors.

中文翻译：

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调整锚定在 NiCo2O4 纳米线上的 NiMoO4 纳米片的形态和尺寸：用于高能量密度非对称超级电容器的优化核壳混合

摘要 核壳结构因其优化的物理/化学性质和在许多能源相关应用中的潜力而激发了日益增长的研究兴趣。在这项工作中，采用简便的两步水热退火方法在泡沫镍基底上合成了分层核壳 NiCo2O4@NiMoO4 纳米阵列，并通过控制 NiMoO4 前驱体的生长时间（2h、5h 和 8h），获得了三种不同形态的获得了 NiMoO4 纳米片的尺寸和尺寸，并研究了它们依赖于形态的电化学性能。结果表明，NiCo2O4@NiMoO4/NF (5h) 混合电极在 5 A g-1 下表现出明显增强的 2806 F g-1 比电容，几乎是原始单组分 NiCo2O4 电极（974 F g-1）的三倍。 1）。优异的性能归因于多孔分级结构和合理的形貌和纳米片厚度，可以降低电子转移电阻并减轻重复氧化还原反应过程中的应变。此外，组装的 NiCo2O4@NiMoO4 (5h)//活性炭非对称超级电容器显示出 64.2 Wh kg-1 (750 W kg-1) 的高能量密度和良好的循环耐久性，5000 次循环后比电容保持率为 87.7%。这项工作为合成用于超级电容器的高性能核壳电极提供了一种新的形态可控方法。组装好的 NiCo2O4@NiMoO4 (5h)//活性炭非对称超级电容器显示出 64.2 Wh kg-1 (750 W kg-1) 的高能量密度，以及 5000 次循环后比电容保持率 87.7% 的良好循环耐久性。这项工作为合成用于超级电容器的高性能核壳电极提供了一种新的形态可控方法。组装好的 NiCo2O4@NiMoO4 (5h)//活性炭非对称超级电容器显示出 64.2 Wh kg-1 (750 W kg-1) 的高能量密度，以及 5000 次循环后比电容保持率 87.7% 的良好循环耐久性。这项工作为合成用于超级电容器的高性能核壳电极提供了一种新的形态可控方法。