Boosted Electrochemical Performance of Honeycomb-Like NiCu–LDH Nanosheets Anchoring on NiCo₂S₄ Nanotube Arrays for Flexible Solid-State Hybrid Supercapacitors

Abstract

Nickel-based layered hydroxides (LDHs) have aroused much interest as promising battery-type electrodes for hybrid supercapacitors (HSCs) because of their high theoretical capacity, good safety, and abundant natural resources; however, the electrochemical performances are still notoriously limited owing to their intrinsically poor electrical conductivity and severe agglomeration features. Herein, an elaborate hierarchical NiCo 2 S 4 @NiCu−LDH nanotube/nanosheet hybrid electrode is designed and fabricated directly on carbon cloth by a facile multistep solution-based strategy. Through the rational engineering of nanostructures and atomic substitution of nickel by copper, the optimized NiCo 2 S 4 @NiCu−LDH hybrid electrode can yield a high areal capacity of 632.0 μAh/cm 2 at a current density of 2 mA/cm 2 and a good rate capability. Furthermore, the assembled flexible solid-state HSC device employing the NiCo 2 S 4 @NiCu−LDH exhibits a maximum volumetric energy density of 2.7 mWh/cm 3 at a power density of 21.3 mW/cm 3 with a robust long-term cycling stability over 2000 cycles and outstanding flexibility under repeated bending tests. Our work demonstrates the possibility of designing and fabricating nickel-based LDHs as superior battery-type electrodes towards highly durable and efficient flexible energy storage devices.

Current advances and challenges in nanosheet-based wearable power supply devices

“…(2020) Depositing on activated carbon cloth 2392 F g −1 85.1% even after 10,000 cycling test 30.1 Wh kg −1 Zhao et al. (2019c) Fabricated on carbon cloth by a facile multistep solution-based strategy – 2,000 cycles 2.7 mWh cm −3 Huang et al. (2020) NiCo 2 O 4 Printing MnO 2 on the nanosheet-based substrate – 93.1% after 5,000 cycles at 50 mA cm −2 37.8 mW cm −3 , Sundriyal and Bhattacharya (2020) Growing on Ni wire – 78% at 0.1 mA after 5,000 cycles 1.44 mWh cm −3 Wang et al.…”

“…The NiCo 2 S 4 @NiCu−LDH had a volumetric energy density up to 2.7 mWh cm −3 , a power density of 21.3 mW cm −3 , and long-term cycling robustness over 2000 cycles. This work exhibited the possibility of designing and fabricating nickel-based LDHs as supercapacitors toward highly efficient and durable soft energy storage devices ( Figure 6 iii) ( Huang et al., 2020 ). Furthermore, a carbon nanosheet-based large-area supercapacitor was proposed by Jun et al.…”

“…The schematic illustrations below present detailed changes of the surface layer for a single fiber and the features of the grown nanostructures at various steps ( Ding et al., 2020 ). (iii) Schematic diagram showing the various production stages of NiCo 2 S 4 @NiCu-LDH nanostructure on carbon cloth ( Huang et al., 2020 ). …”

“… (iii) Schematic diagram showing the various production stages of NiCo 2 S 4 @NiCu-LDH nanostructure on carbon cloth ( Huang et al., 2020 ). …”

Constructing Co(OH)F Nanorods@NiCo‐LDH Nanocages Derived from ZIF‐67 for High‐Performance Supercapacitors

“…[14,15] Thus, intensive research work has been carried out to develop hydroxides with high pseudocapacitance performance. To date, a variety of low-cost hydroxides such as Ni(OH) 2 , [16,17] Co(OH) 2 , [18] CoAl-LDH, [19] CoFe-LDH, [20] NiMn-LDH, [21] NiCo-LDH, [22] and NiCu-LDH [23] have been widely investigated. However, these battery-type hydroxides usually possess poor electrical conductivity and relatively large volume changes during fast charge-discharge tests, thus leading to low cycling stability and poor rate capability.…”