We demonstrate enhanced electrochemical performance through nanoscale composition tuning of cobalt–nickel hydroxide (Co–Ni(OH)₂) films acting as the multiredox electrode for pseudocapacitors. Our electrodes were prepared using a two-step approach: bottom-up synthesis of Co–Ni(OH)₂ nanosheet (NS) colloidal solutions and their immobilization on a metal foam substrate. Co–Ni(OH)₂ NSs were synthesized by kinetically controlled vapor diffusion of ammonia into a metal precursor solution. A highly stable and chemically uniform Co–Ni(OH)₂ NS colloid was synthesized in a liquid medium (water and formamide) to afford Co_1–xNi_xOH₂ NSs (0 < x < 1). Horizontally aligned Co–Ni(OH)₂ NSs were directly immobilized on the nickel substrate using an electrophoretic deposition (EPD) method, and their electrochemical characteristics were investigated according to the Co/Ni molar ratio in the electrodes. Oxidation potentials of the electrode gradually shifted from 0.04 to 0.31 V with an increase in the Ni ratio of the metal hydroxide NS electrodes. Moreover, we successfully obtained the multiredox Co–Ni(OH)₂ electrode by nanoscale composition tuning of Co–Ni(OH)₂ NS films, which were accomplished by the preparation of a mixed colloidal solution. The nanoscale multicomposition Co–Ni(OH)₂ NS film showed comprehensive redox behavior from the relative contributions of each Co–Ni(OH)₂ having a different molar ratio of Co/Ni. Optimized multiredox Co–Ni(OH)₂ NS electrodes exhibited a high rate capability of 92% at 50 A g^–1 and good cycle stability with 90.5% after 1,000 cycles. This method offers a route to produce highly stable pseudocapacitor electrodes with a wide operating window.

中文翻译：

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用于多氧化还原伪电容器的钴镍氢氧化物纳米片的纳米级组成调整

我们通过钴-氢氧化镍（Co-Ni（OH）₂）薄膜的纳米级成分调整展示了增强的电化学性能，该薄膜用作伪电容器的多氧化还原电极。我们的电极采用两步法制备：Co-Ni（OH）₂纳米片（NS）胶体溶液的自底向上合成并将其固定在金属泡沫基材上。Co-Ni（OH）₂ NSs是通过动态控制氨在金属前驱体溶液中的蒸汽扩散而合成的。在液体介质（水和甲酰胺）中合成了高度稳定且化学均一的Co-Ni（OH）₂ NS胶体，得到Co _{1– x} Ni _x OH ₂ NSs（0 < x<1）。使用电泳沉积（EPD）方法将水平排列的Co-Ni（OH）₂ NSs直接固定在镍基板上，并根据电极中Co / Ni的摩尔比研究其电化学特性。随着金属氢氧化物NS电极的Ni比的增加，电极的氧化电位从0.04V逐渐移至0.31V。此外，我们通过对Co-Ni（OH）₂ NS膜进行了纳米级成分调整，成功地获得了多氧化还原Co-Ni（OH）₂电极，这是通过制备混合胶体溶液来完成的。纳米级多成分Co-Ni（OH）₂ NS薄膜从每个Co-Ni（OH）的相对贡献中显示出全面的氧化还原行为₂具有不同的Co / Ni摩尔比。优化的多氧化还原Co-Ni（OH）₂ NS电极在50 A g ^–1时具有92％的高倍率能力，在1,000次循环后具有90.5％的良好循环稳定性。该方法提供了一种生产具有宽工作窗口的高度稳定的伪电容器电极的途径。