Supercapacitors hold huge potential to bridge the gap between conventional capacitors and secondary batteries in terms of high-power density, long cycle lifetime and fast charge/discharge rate. Research in the area of transition metal compounds as supercapacitor electrode materials has attracted increasing attention due to the high energy density that can be achieved by these devices compared to electric double-layer capacitors and the long cycle stability when compared to batteries. In this work, we report the one-step synthesis of nickel hydroxide powder and nickel hydroxide directly grown on nickel foam under varying experimental conditions. The formation of flower-like nanostructured α- and β-Ni(OH)₂, assembled from nanosheets, was observed and a suggestion for the formation process is proposed. The α-Ni(OH)₂ electrode obtained has a high specific surface area of 164 m² g⁻¹ and a significantly enhanced specific capacitance (2814 F g⁻¹ at 3 A g⁻¹), both higher than previously reported α-Ni(OH)₂. Information obtained through characterisation of alpha and beta phases by PXRD, SEM, BET, FTIR and TGA were used in combination with electrochemical studies to rationalise the different electrochemical performance of these 2 phases in terms of their cycle stability and capacitance. This provides guidance for further development and future commercial applications of nickel hydroxide materials for energy storage systems.

中文翻译：

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Nanoflower Ni(OH)2 在泡沫镍上原位生长，用于高性能超级电容器电极材料

超级电容器在高功率密度、长循环寿命和快速充电/放电速率方面具有巨大的潜力，可以弥补传统电容器和二次电池之间的差距。过渡金属化合物作为超级电容器电极材料的研究受到越来越多的关注，因为与双电层电容器相比，这些设备可以实现高能量密度，并且与电池相比具有长循环稳定性。在这项工作中，我们报告了在不同实验条件下一步合成氢氧化镍粉末和直接生长在泡沫镍上的氢氧化镍。花状纳米结构α-和β-Ni(OH) _{2 的形成}观察了由纳米片组装而成的 ，并提出了形成过程的建议。获得的 α-Ni(OH) ₂电极具有 164 m ² g ^-1的高比表面积和显着增强的比电容（2814 F g ^-1 at 3 A g ^-1），均高于先前报道的 α-镍(OH) ₂. 通过 PXRD、SEM、BET、FTIR 和 TGA 表征 alpha 和 beta 相获得的信息与电化学研究结合使用，以合理化这两个相在循环稳定性和电容方面的不同电化学性能。这为用于储能系统的氢氧化镍材料的进一步开发和未来商业应用提供了指导。