| Summary: | In this work, mesoporous ZnCo<sub>2</sub>O<sub>4</sub> electrode material with necklace-type nanowires was synthesized by a simple hydrothermal method using water/ethylene glycol mixed solvent and subsequent calcination treatment. The ZnCo<sub>2</sub>O<sub>4</sub> nanowires were assembled by several tiny building blocks of nanoparticles which led to the growth of necklace-type nanowires. The as-synthesized ZnCo<sub>2</sub>O<sub>4</sub> nanowires had porous structures with a high surface area of 25.33 m<sup>2</sup> g<sup>−1</sup> and with an average mesopore of 23.13 nm. Due to the higher surface area and mesopores, the as-prepared necklace-type ZnCo<sub>2</sub>O<sub>4</sub> nanowires delivered a high specific capacity of 439.6 C g<sup>−1</sup> (1099 F g<sup>−1</sup>) at a current density of 1 A g<sup>−1</sup>, decent rate performance (47.31% retention at 20 A g<sup>−1</sup>), and good cyclic stability (84.82 % capacity retention after 5000 cycles). Moreover, a hybrid supercapacitor was fabricated with ZnCo<sub>2</sub>O<sub>4</sub> nanowires as a positive electrode and activated carbon (AC) as a negative electrode (ZnCo<sub>2</sub>O<sub>4</sub> nanowires//AC), which delivered an energy density of 41.87 Wh kg<sup>−1</sup> at a power density of 800 W kg<sup>−1</sup>. The high electrochemical performance and excellent stability of the necklace-type ZnCo<sub>2</sub>O<sub>4</sub> nanowires relate to their unique architecture, high surface area, mesoporous nature, and the synergistic effect between Zn and Co metals.
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