An electrode material with high performance as a key part is highly desirable for supercapacitors. Herein, NiO/Ni metal–organic framework (Ni-MOF) composites were successfully synthesized via the first preparation of NiO nanoflakes and then in situ formation of Ni-MOF over NiO. Particularly, the conversion degree of Ni-MOF from NiO was conveniently tuned by altering the amount of terephthalic acid added in the hydrothermal process. NiO/Ni-MOF-25 with 25% of the conversion ratio of NiO to Ni-MOF possessed superior electrochemical performance with a specific capacity of 163.4 mA h g^–1 (1176.6 F g^–1) at a current density of 1 A g^–1, higher than Ni-MOF (79.3 mA h g^–1) and NiO (79.8 mA h g^–1). The boosted electrochemical performance of NiO/Ni-MOF-25 was attributed to its core-shell configuration, relatively high specific surface area, and enhanced electrical conductivity. The assembled NiO/Ni-MOF-25//activated carbon asymmetrical supercapacitor achieved a maximum energy density of 31.3 W h kg^–1 at a power density of 374.2 W kg^–1 and decent cyclic durability with 88.7% of incipient capacitance after 2000 cycles. Moreover, two asymmetric devices in series constructed 3 months ago could efficiently illuminate a green light-emitting diode (LED) lamp. This work offers a facile way to rationally design and synthesize composite electrode materials for powerful supercapacitors.

中文翻译：

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用于非对称超级电容器的 NiO/Ni 金属-有机骨架纳米结构

作为关键部件的高性能电极材料是超级电容器非常需要的。在此，通过首先制备 NiO 纳米薄片，然后在 NiO 上原位形成 Ni-MOF，成功合成了 NiO/Ni 金属有机骨架（Ni-MOF）复合材料。特别是，通过改变水热过程中加入的对苯二甲酸量，可以方便地调节 NiO 对 Ni-MOF 的转化率。NiO/Ni-MOF-25 具有 25% 的 NiO 到 Ni-MOF 的转化率，具有优异的电化学性能，在 1 A g ^–的电流密度下具有 163.4 mA hg ^–1 (1176.6 F g ^–1 )的比容量^{– 1} , 高于 Ni-MOF (79.3 mA hg ^–1 ) 和 NiO (79.8 mA hg ^–1）。NiO/Ni-MOF-25 增强的电化学性能归因于其核壳结构、相对较高的比表面积和增强的导电性。组装的 NiO/Ni-MOF-25//活性炭非对称超级电容器在 374.2 W kg ^-1的功率密度下实现了 31.3 W h kg ^-1的最大能量密度和良好的循环耐久性，2000 次循环后初始电容为 88.7% . 此外，三个月前串联构建的两个非对称器件可以有效地照亮绿色发光二极管 (LED) 灯。这项工作为合理设计和合成用于强大超级电容器的复合电极材料提供了一种简便的方法。