Hierarchical coral-like MnCo2O4.5@Co-Ni LDH composites on Ni foam as promising electrodes for high-performance supercapacitor

Precise design and in situ synthesis of hollow Co9S8@CoNi-LDH heterostructure for high-performance supercapacitors

Layered double hydroxides (LDHs) and metal sulfides (MSs) have been widely used as promising electrode materials for supercapacitors, and the rational architectural design of MS/LDH heterogeneous structures is critical to optimize large energy storage. Herein, a precisely designed hollow Co9S8 nanotubes@CoNi-LDH nanosheet heterostructure on Ni foam, facilely prepared by an ingenious in situ strategy in this Co9S8 nanoarray was first used as the self-sacrificing template and metal source to in situ synthesize Co-ZIF-67 polyhedron to form the Co9S8@ZIF-67 heterostructure, and then Co9S8@ZIF-67 was in situ etched successfully using Ni2+ ions to form the final Co9S8@CoNi-LDH/NF core-shell nanoarray. This in situ synthetic strategy to fabricate the heterostructure is conducive to boosting the structural stability, modifying the electric structure and regulating the interfacial charge transfer. Due to the synergistic effect and tight heterogeneous interface, Co9S8@CoNi-LDH/NF displayed an outstanding capacitance of 9.65 F cm-2 at a current density of 2 mA cm-2 and excellent capacitance retention rate of 91.7% after 5000 cycles. In addition, the ASC device assembled with AC has an extremely high energy density of 1.0 mW h cm-2 at 2 mA cm-2 and maintains 96.9% capacitance retention after 5000 cycles. This work provides a skillful strategy for the precise design and in situ synthesis of MS/LDH heterostructures with fascinating features for electrochemical energy storage applications.

Enhanced performance of asymmetric supercapacitor based on NiZn-LDH@NiCoSe2electrode materials

While supercapacitors have been widely studied as the next generation of energy storage devices, to develop active electrode materials for enhancing device performance is still challenging. Herein, we fabricated asymmetric supercapacitors based on NiZn-Layered double hydroxide (LDH) @NiCoSe₂hierarchical nanostructures as electrode materials. The NiZn-LDH@NiCoSe₂composites are deposited on Ni foam by a two-step strategy, in which NiZn-LDH nanosheets were firstly grown on Ni foam by hydrothermal method, and then NiCoSe₂particles were prepared by electrodeposition. Due to the synergistic effect between NiZn-LDH and NiCoSe₂, excellent device performance was achieved. In a three-electrode system, the NiZn-LDH@NiCoSe₂exhibits a specific capacitance of 2980 F g^-1at 1 A g^-1. Furthermore, the asymmetric supercapacitor of NiZn-LDH@NiCoSe₂//activated carbon (AC) device was assembled, which exhibits the energy density of 49.2 Wh kg^-1at the power density of 160 W kg^-1, with the capacity retention rate is 91% after 8000 cycles. The results indicates that NiZn-LDH@NiCoSe₂is a promising candidate as electrode materials for efficient energy storage devices.