超级电容器从实验室研究转化为商业化生产仍存在许多挑战, 特别是实验室所用的低质量负载电极无法满足商业应用的需求. 在此, 提出了一种高负载的镍钴双氢氧化物基(NiCo-LDH)超级电容器. 引入高导电性的三维ZnO@C纳米棒支架, 通过溶剂热、高温退火、电化学沉积等方法在碳布上制备了ZnO@C@NiCo-LDH异质结构材料, 实现了高达11.0 mg•cm⁻²的负载. 高导电性的ZnO@C纳米棒可以避免NiCo-LDH纳米片的团聚并促进电子的传输. 具有高容量的外层NiCo-LDH纳米片可继续改善电极表面的电解质离子接触点, 进一步提高材料的比容量. 这种异质结构电极利用二者的协同作用大大提高了电荷存储能力, 展现了优异的电化学性能. 结果表明, 组装的非对称超级电容器ZnO@C@NiCo-LDH//AC在15 mW•cm⁻²的功率密度下, 实现了0.93 mWh•cm⁻²的高能量密度. 在10 mA•cm⁻²的电流密度下循环5000圈后, 容量保持率仍有93.6%, 展现了卓越的稳定性. 本工作为开展新型高质量负载电极提供了一种新思路.

There are still many challenges in the transformation of supercapacitors from laboratory research to industrial application, especially the low-mass load electrodes used in laboratories cannot meet the needs of commercial applications. Herein, we present a highly loaded nickel-cobalt double hydroxide-based (NiCo-LDH) supercapacitor. Three-dimensional ZnO@C nanorod scaffolds with high conductivity were introduced, and ZnO@C@NiCo-LDH heterostructure materials on carbon cloth were prepared by solvothermal, high-temperature annealing, electrochemical deposition and other methods, achieving loading up to 11.0 mg•cm⁻². The typical synthesis process is as follows. Firstly, the neatly arranged ZnO nanorods were grown on the carbon cloth fiber by seed growth method. Then, ZIF-8 nanoparticle coatings were grown in situ on zinc oxide nanorods through etching and recombination in a solution containing 2-methylimidazole. Subsequently, we obtained ZIF-8-derived carbon-coated ZnO nanorods by carbonizing ZnO@ZIF-8 heteronanostructures in nitrogen. During the carbonization process, the ZIF-8 shell is transformed into a carbon layer containing zinc oxide nanoparticles. Finally, NiCo-LDH nanosheets were deposited on the ZnO@C framework by electrochemical cyclic voltammetry. The conductive ZnO@C nanorods can avoid the agglomeration of NiCo-LDH nanosheets and promote the transport of electrons. The outer NiCo-LDH nanosheets with high capacity can continue to improve the electrolyte ion contact points on the electrode surface, further improving the specific capacity of the material. This heterostructure electrode utilizes the synergistic effect of the two to greatly improve the charge storage capacity and exhibits excellent electrochemical performance. The results show that the assembled asymmetric supercapacitor ZnO@C@NiCo-LDH//AC achieves a high energy density of 0.93 mWh•cm⁻² at a power density of 15 mW•cm⁻². After 5000 cycles at a current density of 10 mA•cm⁻², the capacity retention rate is still 93.6%, demonstrating excellent stability. This work provides a new idea for developing new high-mass load electrodes.