Abstract A high-capacitance NiMnO3@NiO nanosheet hybrid material supported on a carbon fiber paper substrate was successfully synthesized for the binder-free electrodes of high-performance supercapacitors. The synthesis involved a two-step solvothermal method followed by annealing. The sample was characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectrophotometry techniques. A series of electrochemical measurements, including cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy, were carried out to evaluate the electrochemical performance of the sample in a three-electrode system. Results showed that the NiMnO3@NiO electrode exhibited a considerably higher specific capacitance (1090 F g−1 or 151.4 mAh g−1 at a current density of 1 A g−1 and 810 F g−1 or 112.5 mAh g−1 at 10 A g−1) in 4 M KOH electrolyte than its corresponding NiMnO3 and NiO electrodes prepared through a simple one-step hydrothermal method followed by annealing (752 F g−1 or 104.4 mAh g−1 for NiMnO3 and 551.8 F g−1 or 76.7 mAh g−1 for NiO). The NiMnO3@NiO electrode also exhibited excellent cycling stability with a capacitance retention of 89.6% after 5000 cycles at 10 A g−1, which primarily benefited from the unique architecture of the hybrid material. The asymmetric supercapacitor device assembled with the NiMnO3@NiO electrode and an activated carbon electrode presented an energy density of 28.1 Wh kg−1 at a power density of 750 W kg−1 and good cycling stability (∼86.7% retention after 5000 cycles). This excellent electrochemical performance indicated the high potential of NiMnO3@NiO as an integrated electrode material for high-performance supercapacitors.

中文翻译：

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用于赝电容器的NiMnO3@NiO纳米片的制备及电化学性能

摘要 成功合成了一种负载在碳纤维纸基材上的高电容NiMnO3@NiO纳米片杂化材料，用于高性能超级电容器的无粘合剂电极。合成包括两步溶剂热法，然后是退火。通过 X 射线衍射、扫描电子显微镜和 X 射线光电子分光光度法技术对样品进行表征。进行了一系列电化学测量，包括循环伏安法、恒电流充放电和电化学阻抗谱，以评估样品在三电极系统中的电化学性能。结果表明，NiMnO3@NiO 电极表现出相当高的比电容（1090 F g-1 或 151.4 mAh g-1，电流密度为 1 A g-1 和 810 F g-1 或 112。5 mAh g-1 at 10 A g-1) 在 4 M KOH 电解液中比通过简单一步水热法制备的相应 NiMnO3 和 NiO 电极然后退火（NiMnO3 为 752 F g-1 或 104.4 mAh g-1） NiO 为 551.8 F g-1 或 76.7 mAh g-1）。NiMnO3@NiO 电极还表现出优异的循环稳定性，在 10 A g-1 下循环 5000 次后电容保持率为 89.6%，这主要得益于混合材料的独特结构。由 NiMnO3@NiO 电极和活性炭电极组装而成的非对称超级电容器装置在 750 W kg-1 的功率密度下具有 28.1 Wh kg-1 的能量密度和良好的循环稳定性（5000 次循环后保留率约为 86.7%）。