Interlaced NiMn-LDH nanosheet decorated NiCo2O4 nanowire arrays on carbon cloth as advanced electrodes for high-performance flexible solid-state hybrid supercapacitors.

The development of flexible energy storage devices for portable and wearable electronics has aroused increasing interest. In this work, three-dimensional hierarchical NiCo2O4@NiMn-LDH nanowire/nanosheet arrays have been successfully fabricated on carbon cloth through a facile hydrothermal and calcination synthetic method. Benefiting from the sophisticated hybrid nanoarchitectures with desirable structure and components, the optimized NiCo2O4@NiMn-LDH hybrid electrode is found to deliver a remarkable specific capacity of 278 mA h g-1 at 2 mA cm-2 and a good rate capability of 89.1% retention at 20 mA cm-2. Detailed analysis of the reaction kinetics for the hybrid electrode clearly indicates the dominant diffusion-controlled contribution to the total capacity. In addition, a flexible solid-state hybrid supercapacitor is assembled by taking NiCo2O4@NiMn-LDH and activated carbon as the cathode and anode, respectively, which manifests a maximum energy density of 47 W h kg-1 at a power density of 357 W kg-1 as well as an excellent long-term cycling stability (95.6% retention after 5000 cycles over 8 mA cm-2). Our work demonstrates the great potential of this core/shell hybrid nanostructure as an advanced battery-type electrode for high-performance flexible energy storage devices.

One-step sulfuration synthesis of hierarchical NiCo2S4@NiCo2S4 nanotube/nanosheet arrays on carbon cloth as advanced electrodes for high-performance flexible solid-state hybrid supercapacitors.

To obtain high-performance hybrid supercapacitors (HSCs), a new class of battery-type electrode materials with hierarchical core/shell structure, high conductivity and rich porosity are needed. Herein, we propose a facile one-step sulfuration approach to achieve the fabrication of hierarchical NiCo2S4@NiCo2S4 hybrid nanotube/nanosheet arrays (NTSAs) on carbon cloth, by taking hydrothermally grown Ni-Co precursor@Ni-Co precursor nanowire/nanosheet arrays (NWSAs) as the starting templates. The optimized electrode of NiCo2S4@NiCo2S4 hybrid NTSAs demonstrates an enhanced areal capacity of 245 µA h cm-2 at 2 mA cm-2 with outstanding rate capability (73% from 2 to 20 mA cm-2) and cycling stability (86% at 10 mA cm-2 over 3000 cycles). In addition, flexible solid-state HSC devices are assembled by using NiCo2S4@NiCo2S4 hybrid NTSAs and activated carbon as the positive and negative electrodes, respectively, which manifest a maximum volumetric energy density of 1.03 mW h cm-3 at a power density of 11.4 mW cm-3, with excellent cycling stability. Our work indicates the feasibility of designing and fabricating core/shell structured metal sulfides through such a facile one-step sulfuration process and the great potential of these materials as advanced electrodes for high-performance HSC devices.