High-Performance Flexible In-Plane Micro-Supercapacitors Based on Vertically Aligned CuSe@Ni(OH)₂ Hybrid Nanosheet Films

Abstract

The orientation and hybridization of ultrathin two-dimensional (2D) nanostructures on interdigital electrodes is vital for developing high-performance flexible in-plane micro-supercapacitors (MSCs). Despite great progress has been achieved, integrating CuSe and Ni(OH) 2 nanosheets to generate advanced nanohybrids with oriented arrangement of each component and formation of porous frameworks remains a challenge, and their application for in-plane MSCs has not been explored. Herein, the vertically aligned CuSe@Ni(OH) 2 hybrid nanosheet films with hierarchical open channels are skillfully deposited on Au interdigital electrodes/polyethylene terephthalate substrate via a template-free sequential electrodeposition approach, and directly employed to construct in-plane MSCs by choosing polyvinyl alcohol−LiCl gel as both the separator and the solid electrolyte. Because of the unique geometrical structure and combination of intrinsically conductive CuSe and battery-type Ni(OH) 2 components, such hybrid nanosheet films can not only resolve the poor conductivity and restacking problems of Ni(OH) 2 nanosheets but also create the 3D electrons or ions transport pathway. Thus, the in-plane MSCs device fabricated by such hybrid nanosheet films exhibits high volumetric specific capacitance (38.9 F cm −3 ). Moreover, its maximal energy and power density can reach 5.4 mW h cm −3 and 833.2 mW cm −3 , superior to pure CuSe nanosheets, and most of reported carbon materials and metal hydroxides/oxides/sulfides based in-plane MSCs ones. Also, the hybrid nanosheet films device shows excellent cycling performance, good flexibility, and mechanical stability. This work may shed some light on optimizing 2D electrode materials and promote the development of flexible in-plane MSCs or other energy storage systems.

Operando Tailoring of Defects and Strains in Corrugated β‐Ni(OH)2 Nanosheets for Stable and High‐Rate Energy Storage

“…[ 9 ] Thus far, tremendous efforts have been devoted to tackle the challenge in promoting the stability of α‐Ni(OH) 2 . The reported approaches include nanostructuring, [ 11 ] composite with conductive material, [ 12–14 ] and doping with other transition metal cations (Al, Co, Mn, etc.). [ 7,9,15 ] Although incremental improvements in the electrochemical stability and rate capability have been demonstrated for α‐Ni(OH) 2 , the long‐term cycling performance and rate capability at large current density are still far from satisfactory.…”

Functionalized Hybridization of 2D Nanomaterials

“…For example, CuSe nanosheets were vertically aligned on Ni(OH) 2 sheets to fabricate porous frameworks, which facilely resolved the poor conductivity and restacking problems of Ni(OH) 2 nanosheets. Moreover, a 3D electrons or ions transport pathway was simultaneously created to exhibit high volumetric specific capacitance (38.9 F cm −3 ), good cycling performance and superb flexibility/mechanical stability . In Ho's work, MoS 2 nanobelts were interfaced on porous Ni(OH) 2 nanosheets to form 2D‐on‐2D hierarchical architectures with impressive capabilities for complementary energy storage and energy conservation, which were further employed for delivering supercapacitive charge storage and electrochromic optical modulation to display bifunctional supercapacitive–electrochromism properties .…”

Synthesis of nickel selenide thin films for high performance all-solid-state asymmetric supercapacitors

“…6 g PVA was added into 50 mL of deionized water and stirred at 85 °C until the solution became limpid, then the solution was cooled to room temperature. After that, the KOH solution was dropped into PVA solution to form gel electrolyte [40,41].…”