The growth of a Ni(OH)₂ coating on conductive carbon substrates is an efficient way to address issues related to their poor conductivity in electrochemical capacitor applications. However, the direct growth of nickel hydroxide coatings on a carbon substrate is challenging, because the surfaces of these systems are not compatible and a preoxidation treatment of the conductive carbon substrate is usually required. Herein, we present a facile preoxidation-free approach to fabricate a uniform Ni(OH)₂ coating on carbon nanosheets (CNs) by an ion-exchange reaction to achieve the in situ transformation of a MgO/C composite to a Ni(OH)₂/C one. The obtained Ni(OH)₂/CNs hybrids possess nanosheet morphology, a large surface area (278 m²/g), and homogeneous elemental distributions. When employed as supercapacitors in a three-electrode configuration, the Ni(OH)₂/CNs hybrid achieves a large capacitance of 2,218 F/g at a current density of 1.0 A/g. Moreover, asymmetric supercapacitors fabricated with the Ni(OH)₂/CNs hybrid exhibit superior supercapacitive performances, with a large capacity of 198 F/g, and high energy density of 56.7 Wh/kg at a power density of 4.0 kW/kg. They show excellent cycling stability with 93% capacity retention after 10,000 cycles, making the Ni(OH)₂/CNs hybrid a promising candidate for practical applications in supercapacitor devices.

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在导电碳基材上生长Ni（OH）₂涂层是解决与电化学电容器应用中导电性差有关的问题的有效方法。但是，在碳基底上直接生长氢氧化镍涂层是有挑战性的，因为这些系统的表面不相容，并且通常需要对导电碳基底进行预氧化处理。在这里，我们提出了一种简便的无预氧化方法，通过离子交换反应在碳纳米片（CNs）上制备均匀的Ni（OH）₂涂层，以实现MgO / C复合材料原位转化为Ni（OH）₂ / C 1。所获得的Ni（OH）₂/ CNs杂化物具有纳米片形态，大表面积（278 m ² / g）和均匀的元素分布。当在三电极配置中用作超级电容器时，Ni（OH）₂ / CNs杂化物在1.0 A / g的电流密度下可达到2,218 F / g的大电容。此外，用Ni（OH）₂ / CNs杂化体制成的不对称超级电容器表现出优异的超级电容性能，在功率密度为4.0 kW / kg时，容量为198 F / g，能量密度为56.7 Wh / kg。它们显示出卓越的循环稳定性，在10,000次循环后具有93％的容量保持率，这使得Ni（OH）₂ / CNs杂化物成为超级电容器器件实际应用的有前途的候选者。

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