Transition metal oxides with high theoretical capacitance are regarded as desired electrode materials for supercapacitors, however, the poor conductivity and sluggish charge transfer kinetics constrain their electrochemical performance. The three-dimensional (3D) coral-like ZnCo₂O₄ nanomaterials with abundant oxygen vacancies were synthesized through a facile hydrothermal method and chemical reduction approach. The introduced oxygen vacancies can provide more active sites and lower the energy barrier, thereby facilitating the kinetics of surface reactions. Furthermore, the abundant oxygen vacancies in metal oxides can function as shallow donors to facilitate charge carrier diffusion, resulting in a faster ion diffusion rate and superior electrochemical conductivity. The electrochemical performance of ZnCo₂O₄ was optimized by the introduction of oxygen vacancies. The ZnCo₂O₄ nanoclusters, reduced by 0.5 M NaBH₄ (ZnCo₂O₄-0.5), exhibit a specific capacitance of 2685.7 F g⁻¹ at 1 A g⁻¹, which is nearly twice that of the pristine ZnCo₂O₄ (1525.7 F g⁻¹ at 1 A g⁻¹). The ZnCo₂O₄-0.5 exhibits an excellent rate capacity (81.9% capacitance retention at 10 A g⁻¹) and a long cycling stability (72.6% specific capacitance retention after 10 000 cycles at 3 A g⁻¹). Furthermore, the asymmetric supercapacitor (ASC, ZnCo₂O₄-0.5 nanoclusters//active carbon) delivers a maximum energy density of 50.2 W h kg⁻¹ at the power density of 493.7 W kg⁻¹ and an excellent cycling stability (75.3% capacitance retention after 3000 cycles at 2 A g⁻¹), surpassing the majority of previously reported ZnCo₂O₄-based supercapacitors. This work is important for revealing the pivotal role of implementing the defect engineering regulation strategy in achieving optimization of both electrochemical activity and conductivity.

中文翻译：

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合理合成具有丰富氧空位的3D珊瑚状ZnCo2O4纳米团簇用于高性能超级电容器

具有高理论电容的过渡金属氧化物被认为是超级电容器理想的电极材料，但其较差的导电性和缓慢的电荷转移动力学限制了其电化学性能。通过简便的水热法和化学还原方法合成了具有丰富氧空位的三维（3D）珊瑚状ZnCo ₂ O ₄纳米材料。引入的氧空位可以提供更多的活性位点并降低能垒，从而促进表面反应的动力学。此外，金属氧化物中丰富的氧空位可以作为浅施主，促进电荷载流子扩散，从而实现更快的离子扩散速率和优异的电化学导电性。通过氧空位的引入优化了ZnCo ₂ O ₄的电化学性能。用0.5 M NaBH ₄ (ZnCo ₂ O ₄ -0.5)还原的ZnCo ₂ O ₄纳米团簇在1 A g ^{-1时表现出2685.7 F g -1}的比电容，几乎是原始ZnCo ₂ O的两倍₄（1525.7 F g ^-1于 1 A g ^-1）。 ZnCo ₂ O ₄ -0.5 表现出优异的倍率容量（10 A g ^{-1下的电容保持率为81.9%）和长循环稳定性（3 A g -1}下10000次循环后比电容保持率为72.6% ）。此外，非对称超级电容器（ASC，ZnCo ₂ O ₄ -0.5纳米团簇//活性炭）在493.7 W kg ^-1的功率密度下提供了50.2 W h kg ^-1的最大能量密度和优异的循环稳定性（75.3％）在2 A g ^-1 )下3000次循环后的电容保持率，超过了之前报道的大多数ZnCo ₂ O ₄基超级电容器。这项工作对于揭示实施缺陷工程调控策略在实现电化学活性和电导率优化中的关键作用具有重要意义。