Improvement in the capacitance and energy density of zinc cobalt oxide based materials is vital for creating supercapacitors with excellent electrochemical performance. We synthesized Cu doped zinc cobalt oxide (Zn_1–xCu_xCo₂O₄) nanostructures via a facile hydrothermal method to accomplish excellent supercapacitive performance. Significantly, the incorporation of Cu into ZnCo₂O₄ brings a 2 times increase in specific surface area (52 m² g^–1) and decrease in charge transfer resistance for the Zn_0.7Cu_0.3Co₂O₄ (x = 0.3) sample. Consequently, the Cu doped Zn_0.7Cu_0.3Co₂O₄ electrode displays a high specific capacitance of 1425 F g^–1, which is 1.55-fold increased as compared to 917 F g^–1 of the pristine ZnCo₂O₄ electrode. About 96% of capacitance is retained by the Zn_0.7Cu_0.3Co₂O₄ after 2000 charge–discharge cycles. Later, a Zn_0.7Cu_0.3Co₂O₄ based solid-state symmetric supercapacitor has been fabricated, which displays a potential window of 1.5 V with enlarged cycling stability. The assembled device shows a high energy density of 55 W h kg^–1 at a power density of 2621 W K g^–1 and successfully lightens the yellow LED of 1.5 V. The immense improvement in electrochemical performance is credited to the increased surface area and electronic conductivity of the electrode. The obtained results clearly evidenced that the fabricated solid-state symmetric supercapacitor has the potential to be used in flexible energy storage devices.

中文翻译：

---

铜掺杂的氧化锌钴基固态对称超级电容器：高能量密度的有前途的关键

改善基于钴酸锌锌的材料的电容和能量密度对于制造具有优异电化学性能的超级电容器至关重要。我们通过一种简便的水热法合成了掺铜的氧化锌钴（Zn _{1– x} Cu _x Co ₂ O ₄）纳米结构，以实现优异的超电容性能。值得注意的是，对于Zn _0.7 Cu _0.3 Co ₂ O ₄（ZnCo ₂ O _4），Cu的掺入使比表面积（52 m ² g ^–1）增大了2倍，电荷转移电阻降低了2倍。x = 0.3）样本。因此，掺杂Cu的Zn _0.7 Cu _0.3 Co ₂ O ₄电极显示出1425 F g ^–1的高比电容，与原始ZnCo ₂ O ₄电极的917 F g ^–1相比，增加了1.55倍。经过2000次充放电循环后，Zn _0.7 Cu _0.3 Co ₂ O ₄保留了约96％的电容。后来，Zn _0.7 Cu _0.3 Co ₂ O ₄制作了基于固态的对称对称超级电容器，该电容器具有1.5 V的电势窗口，并具有增强的循环稳定性。组装后的器件在2621 WK g ^–1的功率密度下显示出55 W h kg ^–1的高能量密度，并成功点亮了1.5 V的黄色LED。电化学性能的极大提高归功于表面积和电子面积的增加。电极的电导率。所获得的结果清楚地证明了所制造的固态对称超级电容器具有在柔性储能装置中使用的潜力。