Effects of Co/Ni Ratio on the Supercapacitive Properties of α‐Form Hydroxides

α‐Form Co x Ni 1– x hydroxides with different Co/Ni ratios were synthesized by a chemical co‐precipitation method under mild conditions. The effects of Co/Ni ratio on the structure, morphology, and supercapacitive properties of α‐form Co x Ni 1– x hydroxides were investigated in detail. α‐Form Co x Ni 1– x hydroxides had structures similar to those of hydrotalcite and α‐Co(OH) 2 , and they exhibited better electrochemical performance than α‐Co(OH) 2 on testing by XRD, FTIR, and electrochemical performance (when x ≠ 0). The highest specific capacitance at 1 A g –1 for α‐form Co x Ni 1– x hydroxides (for x = 0.2) is 1696.7 F g –1 . An asymmetric supercapacitor packaged with Co 0.6 Ni 0.4 hydroxide and activated carbon as positive and negative material, respectively, had an energy density of 23.5 Wh kg –1 at a power density of 412.5 W kg –1 .