CoNi2S4 Nanoplate Arrays Derived from Hydroxide Precursors for Flexible Fiber-Shaped Supercapacitors

Effect of Sulfur Vacancies of CoNi2S4 on Its Electrochemical Performance in Hybrid Supercapacitors

Ternary cobalt nickel sulfides are considered promising electrode materials due to their unique physical properties. However, its capacitive performance is still limited by the insufficient material utilization efficiency. Here, we design and fabricate CoNi2S4 with nanorods and hairy-petal-like nanosheets on nickel foam (NF) as an excellent self-standing electrode for a hybrid supercapacitor (HSC). The CoNi2S4 electrode material was synthesized on the NF substrate by cobalt organic framework (Co-MOF) conversion and introducing sulfur ion and nickel ion exchange. The CoNi2S4 electrode material with sulfur vacancies was controlled by regulating the reduction time, and then electrochemical analysis and comparison were performed. The results demonstrate that the synergistic effect of the MOF-derived CoNi2S4 skeleton and sulfur vacancies can significantly improve the electrochemical activity of nickel cobalt sulfide. The CoNi2S4 electrode exhibits a superior high specific capacitance of 5.24 F/cm2 at a current density of 3 mA/cm2. Furthermore, the assembled CoNi2S4-60//AC HSC displays a high energy density of 59.41 Wh/kg and a power density of 999.98 W/kg. Even after 10,000 continuous charge-discharge cycles, its initial capacitance was retained at 89.24%. These results demonstrate the feasibility and practicality of CoNi2S4-60 as an electrode material, showcasing its potential for real-world applications.

Fiber‐Shaped Electronic Devices

Textile electronics embedded in clothing represent an exciting new frontier for modern healthcare and communication systems. Fundamental to the development of these textile electronics is the development of the fibers forming the cloths into electronic devices. An electronic fiber must undergo diverse scrutiny for its selection for a multifunctional textile, viz., from the material selection to the device architecture, from the wearability to mechanical stresses, and from the environmental compatibility to the end‐use management. Herein, the performance requirements of fiber‐shaped electronics are reviewed considering the characteristics of single electronic fibers and their assemblies in smart clothing. Broadly, this article includes i) processing strategies of electronic fibers with required properties from precursor to material, ii) the state‐of‐art of current fiber‐shaped electronics emphasizing light‐emitting devices, solar cells, sensors, nanogenerators, supercapacitors storage, and chromatic devices, iii) mechanisms involved in the operation of the above devices, iv) limitations of the current materials and device manufacturing techniques to achieve the target performance, and v) the knowledge gap that must be minimized prior to their deployment. Lessons learned from this review with regard to the challenges and prospects for developing fiber‐shaped electronic components are presented as directions for future research on wearable electronics.

Enhanced faradic activity by construction of p-n junction within reduced graphene oxide@cobalt nickel sulfide@nickle cobalt layered double hydroxide composite electrode for charge storage in hybrid supercapacitor

The intrinsic faradic reactivity is the uppermost factor determining the charge storage capability of battery material, the construction of p-n junction composing of different faradic components is a rational tactics to enhance the faradic activity. Herein, a reduced graphene oxide@cobalt nickle sulfide@nickle cobalt layered double hydroxide composite (rGO@CoNi₂S₄@NiCo LDH) with p-n junction structure is designed by deposition of n-type nickle cobalt layered double hydroxide (NiCo LDH) around p-type reduced graphene oxide@cobalt nickle sulfide (rGO@CoNi₂S₄), the charge redistribution across the p-n junction enables enhanced faradic activities of both components and further the overall charge storage capacity of the resultant rGO@CoNi₂S₄@NiCo LDH battery electrode. As expected, the rGO@CoNi₂S₄@NiCo LDH electrode can deliver high specific capacity (C_s, 1310 ± 26 C g^-1 at 1 A g^-1) and good cycleability (77% C_s maintaining ratio undergoes 5000 charge-discharge cycles). Furthermore, the hybrid supercapacitor (HSC) based on the rGO@CoNi₂S₄@NiCo LDH p-n junction battery electrode exports high energy density (E_cell, 57.4 Wh kg^-1 at 323 W kg^-1) and good durability, showing the prospect of faradic p-n junction composite in battery typed energy storage.