Honeycomb porous heterostructures of NiMo layered double hydroxide nanosheets anchored on CoNi metal–organic framework nano-blocks as electrodes for asymmetric supercapacitors

The CoNi-MOF (CNM) is successfully grown on activated carbon cloth (AC) by using Ni(OH)2 as precursors, and NiMo-LDH (NML) nanosheets are further in situ anchored on its surface to form honeycomb porous heterostructures. Moreover, the asymmetric supercapacitor assembled by NML@CNM/AC and annealed activated carbon cloth exhibits excellent energy storage capacity as well as good cycling stability and rate capability. [Display omitted] •Innovatively pre-growing Ni(OH)2 nanosheets as precursors to achieve the controllable growth of CoNi-MOF on activated carbon cloth (AC).•Honeycomb porous heterostructures with excellent performance are obtained by in-situ anchored NiMo-LDH nanosheets on CoNi-MOF nano-blocks.•The asymmetric supercapacitors assembled by NiMo-LDH@CoNi-MOF/AC and annealed AC present excellent energy storage performance. Supercapacitors (SCs) have the advantages of high power density, long cycle life, and fast charging/discharging rates, but relatively low energy density limits their practical application prospects. The key to improving the energy density of supercapacitors is to develop electrode materials with excellent performance. Metal-organic frameworks (MOFs) used for electrochemical energy storage have emerged as a research hotspot due to their adjustable microstructure, porosity, and high specific surface area. To address the demands of high-performance supercapacitors, composite nanomaterials can be prepared by rationally designing MOFs. Herein, CoNi-MOF nano-blocks are grown on the carbon cloth, and ultrathin NiMo layered double hydroxides (NiMo-LDH) nanosheets are further anchored on its surfaces to form a honeycomb porous heterostructure (NiMo-LDH@CoNi-MOF). The porous heterostructures increase the electrochemically active specific surface area and shorten the charge transfer distance, possessing ultra-high capacitance of 15.6 F/cm2 at 1 mA/cm2. Furthermore, utilizing annealed activated carbon cloth (AAC) as the negative electrode, the assembled NiMo-LDH@CoNi-MOF-2//AAC asymmetric supercapacitor possesses an energy density of 1.10 mWh/cm2 at a power density of 4 mW/cm2, and a capacitance retention of 97.8 % after 10,000 cycles. This material exhibits distinctive nanostructures and favorable electrochemical characteristics, providing a unique idea for preparing supercapacitors with high energy density and power density.