High‐Stacking‐Density, Superior‐Roughness LDH Bridged with Vertically Aligned Graphene for High‐Performance Asymmetric Supercapacitors

Abstract

The high-performance electrode materials with tuned surface and interface structure and functionalities are highly demanded for advanced supercapacitors. A novel strategy is presented to conFigure high-stacking-density, superior-roughness nickel manganese layered double hydroxide (LDH) bridged by vertically aligned graphene (VG) with nickel foam (NF) as the conductive collector, yielding the LDH-NF@VG hybrids for asymmetric supercapacitors. The VG nanosheets provide numerous electron transfer channels for quick redox reactions, and well-developed open structure for fast mass transport. Moreover, the high-stacking-density LDH grown and assembled on VG nanosheets result in a superior hydrophilicity derived from the tuned nano/microstructures, especially microroughness. Such a high stacking density with abundant active sites and superior wettability can be easily accessed by aqueous electrolytes. Benefitting from the above features, the LDH-NF@VG can deliver a high capacitance of 2920 F g at a current density of 2 A g , and the asymmetric supercapacitor with the LDH-NF@VG as positive electrode and activated carbon as negative electrode can deliver a high energy density of 56.8 Wh kg at a power density of 260 W kg , with a high specific capacitance retention rate of 87% even after 10 000 cycles.

Synthesis of NiMn-LDH Nanosheet@Ni3S2 Nanorod Hybrid Structures for Supercapacitor Electrode Materials with Ultrahigh Specific Capacitance

“…1e ), the peaks at 162.0 and 163.8 eV with the addition of a satellite peak at 168.6 eV can be assigned to S signal in Ni 3 S 2 phase 35 . Moreover, the Raman spectrum of as-prepared hybrid material (Figure S1b ) displays three peaks at 345, 543 and 1040 cm −1 , which can be assigned to the characteristic bands of Ni 3 S 2 , the metal–oxygen–metal (M–O–M) bonds of NiMn-LDH, and the CO 3 2– in the interlayers of NiMn-LDH, repectively 36 , 37 . All these results indicate that the NiMn-LDH@Ni 3 S 2 hybrid structure has been indeed formed.…”

Boosting the cycling stability of transition metal compounds-based supercapacitors

“…[202] Meanwhile, 3D graphene has been used as scaffolds for direct growth of transition metal based materials because of their unique interconnected macroporous structure, high specific areas, lightweight and flexible mechanical properties. [101,146,[203][204][205][206][207][208][209][210] The hydrophilic functional groups on the surface of 3D graphene help to obtain a compact growth of the transition metal compounds on the graphene surface.…”

High performance hybrid supercapacitor device based on cobalt manganese layered double hydroxide and activated carbon derived from cork (Quercus Suber)

“…Several types of EDLC materials have been utilized as SCs material electrodes. These includes carbide-derived carbons, graphene, carbon-nanofibers, zeolite-templated carbon, carbon nanotubes (CNTs) and activated carbon [10][11][12][13][14][15][16][17][18][19][20][21][22]. Amongst these materials, the most commonly used in hybrid devices is activated carbon due to its high specific surface area (SSA), ease of production, light weight, relatively low cost, good porosity and presence of pseudocapacitive charge transfer mechanism which can contribute to increased specific capacitance due to the presence of functional groups [3,8,[23][24][25].…”