The development of nickel-based electrode materials has always been a hot spot in the field of electrochemical energy. It is well known that nickel hydroxide nanostructures in situ grown on nickel foam has been well applied in supercapacitors, which can further be employed as a precursor to fabricate other nickel-based compounds and their composites as electrode materials. In this work, the controllable growth and phase transformation from initial β-Ni(OH)₂ to nitrated α-Ni(OH)₂ [i.e. Ni₃(NO₃)₂(OH)₄] in situ on nickel foam have been successfully achieved through a traditional mild hydrothermal route by tuning the concentration of reactants. The electrochemical studies show that the specific capacitance of α-type nickel hydroxide electrode is much higher than that of β-type. The former exhibits a large gravimetric capacitance of 2075 F g⁻¹ at a current density of 0.5 A g⁻¹. The asymmetric supercapacitor can provide a high specific energy of 31.5 Wh kg⁻¹ at a specific power of 388 W kg⁻¹ within a voltage window of 1.55 V. Therefore, this research develops a controllable preparation methodology for electrode materials of high-performance supercapacitors, which are also of great significance for the design of more new nickel-based electrode materials.

镍基电极材料的开发一直是电化学能源领域的热点。众所周知，在泡沫镍上原位生长的氢氧化镍纳米结构在超级电容器中得到了很好的应用，可进一步用作制备其他镍基化合物及其复合材料作为电极材料的前驱体。在这项工作中，从初始 β-Ni(OH) ₂到硝化的 α-Ni(OH) ₂ [即 Ni ₃ (NO ₃ ) ₂ (OH) ₄的可控生长和相变] 通过调节反应物的浓度，通过传统的温和水热途径​​成功地实现了泡沫镍上的原位。电化学研究表明，α型氢氧化镍电极的比电容远高于β型。前者在0.5 A g ^-1的电流密度下表现出2075 F g ^-1的大重量电容。非对称超级电容器在388 W kg ^-1的比功率下可提供31.5 Wh kg ^-1的高比能量 在1.55 V的电压窗口内。因此，本研究开发了高性能超级电容器电极材料的可控制备方法，对于设计更多新型镍基电极材料也具有重要意义。