ZIFs骨架型双壳层纳米笼状CoS/NiCo2S4的制备及其电化学性能

采用离子刻蚀和化学气相沉积法制备出具有沸石咪唑酯骨架(ZIFs)型双壳层纳米笼状的CoS/NiCo_2S_4并组装成超级电容器。该结构有较大的比表面积(98 m2·g-1),合适的孔道(孔径4 nm),且保留了ZIFs骨架构型。作为电极活性材料时,具有良好的结构稳定性和电化学活性,有利于增强所组装的超级电容器的循环稳定性和比容量。在三电极体系中,在1 A·g-1的电流密度下,容量为1 230 F·g-1;在3 A·g-1电流密度下循环9 000圈后,初始电容保持率为76.6%。在以该电极、活性炭电极与KOH/聚乙烯醇(PVA)凝胶态电解质组装的器件中,当功率密度为702 W·kg-1时,能量密度达31.6 Wh·kg-1;在7 056 W·kg-1的高功率密度下,仍保持16.5 Wh·kg-1的能量密度。

Preparation and Electrochemical Properties of ZIF-Skeleton Double-Shell Nanocage CoS/NiCo2S4

Double-shell nanocage CoS/NiCo₂S₄ was prepared by ion erosion and chemical vapor deposition using ZIF-67. The supercapacitor based on CoS/NiCo₂S₄ exhibited high specific capacitance and stability, due to its high specific surface area (98 m²·g^-1), abundant interconnected channel (4 nm pole diameter), and stable cavity skeleton. The three-electrode cell based on CoS/NiCo₂S₄/Ni foam maintained 76.6% initial capacitance at 3 A·g^-1 current density after 9 000 cycles. The cell gained a specific capacitance of 1 230 F·g^-1 at 1 A·g^-1 due to increasing active sites and rapid electron/ion transports for Faradaic reactions. The results can reflect the superior electrochemical performance of double-shell nanocage CoS/NiCo₂S₄ on specific capacitance and cycling stability. The supercapacitor was assembled by CoS/NiCo₂S₄/Ni foam, active carbon electrode and KOH/polyvinyl alcohol gel electrolyte. The device retention was 74.8% at a current density of 3 A·g^-1 after 7 000 cycles. The device also achieved an energy density of 16.5 Wh·kg^-1 at a high power density of 7 056 W·kg^-1. Even at a power density of 702 W·kg^-1, a high energy density of 31.6 Wh·kg^-1 can be obtained. The asymmetric device exhibited excellent energy density, power density and cycle stability. In a practical application testing, two series-connected solid-state supercapacitors provided stable electrical energy, enabling the LEDs to be successfully illuminated.