One‐Step Preparation of NiV‐LDH@CNT Hierarchical Composite for Advanced Asymmetrical Supercapacitor

As one of the supercapacitor materials, nickel–vanadium layered double hydroxide (NiV‐LDH) has received wide attention, but poor electrochemical stability and capacitance constrain their applications. Carbon nanotubes (CNTs) enable solving these issues. Herein, NiV‐LDH@CNT is well designed and prepared through a facile one‐step refluxing method, which is free of high temperature and complicated equipment. Benefiting from the hierarchical and accessible structure, the NiV‐LDH@CNT composite indicates a high specific capacitance (1493 F g −1 at a current density of 1 A g −1 and 432 F g −1 at 50 A g −1 ). It also has 68.8% cycling durability after 1000 charge/discharge cycles at 20 A g −1 , compared with that of NiV‐LDH of 28.1%. Furthermore, the asymmetric supercapacitors (ASCs) with activated carbon (AC) and NiV‐LDH@CNT are fabricated by the screen‐printing method. Surprisingly, the as‐fabricated NiV‐LDH@CNT//AC ASC device can achieve an ideal specific capacitance (85 F g −1 at 2 A g −1 ) and a large energy density (95.6 Wh kg −1 at a power density of 5417.8 W kg −1 ), which can be a great promising candidate for electrodes in the energy storage device.