High-Performance, Flexible, All-Solid-State Wire-Shaped Asymmetric Micro-Supercapacitors Based on Three Dimensional CoNi₂S₄ Nanosheets Decorated–Nanoporous Ni–Zn–P Film/Cu Wire

Abstract

Demand increasing for next generation portable and miniaturized electronics has aroused much interest to explore microscale and lightweight energy storage devices. Herein, we demonstrate successful development of flexible wire-shaped microsupercapacitors (micro-SCs) based on novel CoNi 2 S 4 /E-NZP film@Cu wire electrode. The etched Ni−Zn−P (E-NZP) film was synthesized by directly deposition of NZP film on Cu wire, followed by a chemical etching process. Alkaline etching treatment provides a micro-and mesoporous structure with high surface area and facilitates the penetration of electrolyte ions into the electrode matrix. Then, CoNi 2 S 4 nanosheets as electroactive material are electrochemically grown onto the E-NZP film@CW electrode under a constant potential. The synergistic effects contributed by various components inside the CoNi 2 S 4 /E-NZP@CW electrode deliver superior performances with a high specific capacitance of 1.12 F cm −1 , 8.9 F cm −2 , and 889.68 F cm −3 at 4 mA cm −2 , outstanding rate capability (0.66 F cm −1 , 5.3 F cm −2 , and 529.02 F cm −3 at 80 mA cm −2 ) and long-term cycling stability (93.4% capacitance retention after 7000 cycles). Moreover, a flexible solid-state asymmetric micro-SC is fabricated using CoNi 2 S 4 /E-NZP film @CW as the positive electrode and rGO-coated carbon fiber (rGO/CF) as the negative electrode. The fabricated device exhibits high length, areal and volumetric capacitances of C L : 40 mF cm −1 , C A : 0.241 F cm −2 and C V : 18.54 F cm −3 , good mechanical stability with a maximum energy (E L , 18 μW h cm −1 ; E A , 108.4 μW h cm −2 ; and E V , 8.34 mW h cm −3 ), and power densities (P L , 1454 μW cm −1 ; P A , 9280 μW cm −2 ; and P V , 716.9 mW cm −3 ). This work provides a new and facile approach to develop high-performance wire-shaped electrodes as a new generation in energy storage applications.

Construction of a Ternary Nanocomposite, Polypyrrole/Fe–Co Sulfide-Reduced Graphene Oxide/Nickel Foam, as a Novel Binder-Free Electrode for High-Performance Asymmetric Supercapacitors

“…However, low electrical conductivity and poor cycling performance are the major drawbacks in the practical applications of this material group. − Recently, transition metal sulfides have been investigated as a new class of pseudocapacitors with excellent properties for application in supercapacitors. Transition metal sulfides, especially ternary transition metal sulfides, exhibit high intrinsic conductivity, much higher electrochemical capacity, and excellent thermal and mechanical stability compared to the corresponding metal oxides and even binary and single-component metal sulfides; these properties can be attributed to different valence states during their redox reactions and smaller band gap energy. − For instance, nickel–cobalt sulfide (NiCo 2 S 4 ) exhibits an electrical conductivity about 100 times larger than nickel cobalt oxide (NiCo 2 O 4 ) and 4 times larger than nickel or cobalt sulfides. − …”

Cauliflower-Like Ni/MXene-Bridged Fiber-Shaped Electrode for Flexible Microsupercapacitor

“…The Randles−Sevcik equation can be used to calculate the ion diffusion coefficient in active materials. 4,46 The OH − coefficient diffusion of the Ni@CW, Ni-Ti 3 C 2 @CW, and Ni(OH) 2 -Ni-Ti 3 C 2 @CW electrodes are 4 × 10 −6 , 2 × 10 −5 , and 5 × 10 −5 , respectively. The higher coefficient diffusion of Ni(OH) 2 -Ni-Ti 3 C 2 @CW indicates faster ion diffusion kinetics, which is due to its porous and nanoscale structure.…”

“…However, the low surface area and contact conductance of the metal wires to semiconductor active materials lead to their limited areal and volumetric energy densities as being crucial factors for portable electronics. 4,15,16 Improving geometrical capacitances of these FSCs remains a key challenge in boosting geometrical energy densities (E = 1/ 2CV 2 ). Optimizing the design of the electrode materials or current collector without changing the chemistry of the electrode materials can address this issue.…”

“…17 Shahrokhian and Naderi reported a 3D porous Ni-Zn-P scaffold on Cu wire for loading CoNi 2 S 4 nanosheets that delivered a high volumetric capacitance of 889.68 Fcm −3 (8.9 Fcm −2 , 1.12 Fcm −1 ) at 4 mAcm −2 . 4 Moreover, 2D materials that have great electrical conductivity and specific surface area are good supporting materials for FSC substrates. For instance, Gao et al designed 3D Cu foam/ graphene sheets as a scaffold to bridge the NiCo LDH active substance with a nickel wire substrate and reached the areal specific capacitance of 1729.41 mF cm −2 .…”

Cobalt vanadium chalcogenide microspheres decorated with dendrite-like fiber nanostructures for flexible wire-typed energy conversion and storage microdevices

“…[1][2][3][4][5][6][7] Fiber-shaped microsupercapacitors (microSCs) characterized by high flexibility, tiny volume, light weight, and excellent wearability have received considerable attention in next-generation flexible miniaturized energy storage devices. [8][9][10][11][12] However, their low specific capacitance and working voltage have limited their practical application in high-performance wearable and portable devices. [13][14][15][16] The fabrication of fiber-shaped asymmetric microsupercapacitors (FSAMSCs), which combine a carbonbased negative electrode as the power source with a batterytype positive electrode based on fast redox reactions as the energy source, is a promising strategy to increase the voltage window and can further increase the energy density of the fiber-shaped microSCs.…”