In this work, mesoporous NiCo₂O₄ nanoneedle arrays grown on a nickel foam substrate are fabricated by a facile hydrothermal route. The as-synthesized NiCo₂O₄ products as binder-free electrodes for supercapacitors show a superior discharge areal capacity of 0.998 C cm⁻² at a current density of 2 mA cm⁻², excellent rate performance (60.25% retention with current density increasing from 2 mA cm⁻² to 200 mA cm⁻²) and outstanding cycling stability (about 19.3% loss after 12 000 cycles at a current density of 20 mA cm⁻²). An assembled supercapacitor using a NiCo₂O₄ electrode as the positive electrode delivers a volumetric energy density of 0.33 mW h cm⁻³ at a volumetric power density of 12 mW h cm⁻³ and still achieves 63.6% retention with the volumetric power density increasing to 120 mW h cm⁻³. Surprisingly, 140.6% capacity retention is attained after 8000 cycles at 10 mA cm⁻².

中文翻译：

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具有优异循环稳定性的中 孔NiCo ₂ O ₄纳米针阵列作为超级电容器电极材料

在这项工作中，通过便捷的水热法制备了在泡沫镍基材上生长的中孔NiCo ₂ O ₄纳米针阵列。合成后的NiCo ₂ O ₄产品作为超级电容器的无粘合剂电极，在2 mA cm ^-2的电流密度下显示出0.998 C cm ^-2的优异放电面积容量，优异的倍率性能（随着电流密度的增加，保留率达60.25％）从2 mA cm ^-2到200 mA cm ^-2）和出色的循环稳定性（在20 mA cm ^-2的电流密度下进行12 000次循环后损耗约19.3％）。使用NiCo ₂ O ₄的组装超级电容器作为正电极的电极在体积功率密度为12 mW h cm ^-3时提供的体积能量密度为0.33 mW h cm ^-3，并且随着体积功率密度增加到120 mW h cm ^-3，仍实现了63.6％的保留率。令人惊讶地，在10mA cm ^-2的8000次循环之后，达到了140.6％的容量保持率。