Electrodeposited MnS@Ni(OH)2 core-shell hybrids as an efficient electrode materials for symmetric supercapacitor applications

Crystalline-amorphous hybrid CoNi layered double hydroxides for high areal energy density supercapacitor

Crystalline-amorphous hybrid materials have garnered significant attention in the realm of energy storage, yet simultaneously regulating the morphological and electronic structure of crystalline-amorphous hybrid remains a challenge. Herein, crystalline-amorphous hybrid CoNi-layered double hydroxides (CA-CoNi-LDHs) were constructed by a facile chronoamperometry (i-t) electrochemical activation strategy, which allows for dual modulation of both structural transformations and electronic structure of CoNi-layered double hydroxides (CoNi-LDHs). Experimental results demonstrate that the construction of a crystalline-amorphous hybrid can effectively optimize both the morphological and electronic structure of CoNi-LDHs, expose abundant defects, and raise the concentration of active Ni2+ and Co3+ species, which are conducive to increasing the active sites for energy storage. The reduced adsorption energy for OH-, the increased electron density near the Fermi energy level, coupled with the narrowed bandgap energy of CA-CoNi-LDHs are favorable for accelerating electron transfer and enhancing reaction kinetic. Consequently, the CA-CoNi-LDHs@CC electrode with high mass loading (18.8 mg cm-2) delivers an impressive areal capacitance of 13,070 mF cm-2 at 5 mA cm-2, along with exceptional cycling stability. Moreover, the assembled asymmetric supercapacitor based on CA-CoNi-LDHs@CC possesses a high areal energy density of 0.71 mWh cm-2 at a power density of 3.95 mW cm-2. This work proves that construction of crystalline-amorphous hybrid materials is a viable strategy for achieving high energy density storage.

Design and construction of heterostructured Zn2V2O7 cubes and hexagons as an electrode material for high-performance asymmetric supercapacitor applications

Hierarchical nanostructures have harvested noteworthy attention lately owing to their remarkable capabilities in the fields of energy storing and transformation, catalysis, and electrical devices. We established an effort less and template-free synthetic method to create hierarchical hetero nanostructures of Zn2V2O7, taking into account the benefits of hierarchical nanostructures, we investigated the performance of HNs (Hierarchical Nanostructures) as electrochemical supercapacitors. Electrochemical tests were tested in a 6 M KOH solution to assess their capabilities. The Zn2V2O7 electrode's measured specific capacitance was 750F/g at 1 A/g, with outstanding stability and an excellent retention capacity of 85 % later 5000 cycles in three- electrode electrochemical cells. Asymmetric device such as Zn2V2O7//AC provides a specific capacitance of 76.8F/g at 1 A/g with energy and power densities of 27.3 Wh kg-1 and 800 W kg-1 respectively. The device withstands 85 % of its initial capacity after 5000 continuous GCD cycles at 10 A/g. The outstanding performance observed clearly demonstrates the significant potential and practical utility of Zn2V2O7 in the realm of more efficient energy storage applications.

Construction and application of NiCo2O4@MnS composite with hierarchical structure for hybrid supercapacitor

The development of an electrochemical energy storage system with exceptional performance is an important way to address the energy crisis and environmental pollution of the modem world. In this study, an NiCo2O4@MnS composite with a unique hierarchical structure has been successfully synthesized on an NF substrate using the hydrothermal-electrodeposition method. The results indicate that NiCo2O4@MnS possesses superior specific capacitance and excellent cycling stability. At a current density of 2 A g-1, its specific capacitance can reach 2100 F g-1, while the capacitance retention is still 76% after 10 000 cycles at 10 A g-1. Moreover, when the current density is 1 A g-1, the assembled NiCo2O4@MnS//AC device can deliver a specific capacitance of 203 F g-1, and the energy density is up to 55 W h kg-1 at a power density of 697 W kg-1. These outstanding electrochemical properties of NiCo2O4@MnS can be ascribed to the increase in ion diffusion, specific surface area and electronic conductivity due to its unique hierarchical structure and introduction of MnS.

Recent Developments in Electrodeposition of Transition Metal Chalcogenides-Based Electrode Materials for Advance Supercapacitor Applications: A Review

High-performance supercapacitive electrode materials have received significant attention from researchers worldwide, thus aiming for comparable performance similar to the extensively used rechargeable batteries. For emerging energy storage technologies like flexible supercapacitors, transition metal chalcogenides (TMCs) have been in the spotlight due to their promising electrochemical features compared to other electrode materials. Among the synthesis techniques, electrodeposition-mediated preparation of thin films of TMCs offered an affordable binder-free approach for electrode fabrication that effectively improved the supercapacitor performance. Hence, this review mainly focussed on the electrodeposition-based syntheses of single/ multinary chalcogenides and their composites for supercapacitors applications. Further, the effects of different deposition parameters were discussed for boosting the supercapacitor performance. Finally, this review outlined the existing challenges and future perspectives in this research domain, which will assist the upcoming exploration in the energy storage field.

Series of Halogen Engineered Ni(OH)2 Nanosheet for Pseudocapacitive Energy Storage with High Energy Density

Ni(OH)2 nanosheet, acting as a potential active material for supercapacitors, commonly suffers from sluggish reaction kinetics and low intrinsic conductivity, which results in suboptimal energy density and long cycle life. Herein, a convenient electrochemical halogen functionalization strategy is applied for the preparation of mono/bihalogen engineered Ni(OH)2 electrode materials. The theoretical calculations and experimental results found that thanks to the extraordinarily high electronegativity, optimal reversibility, electronic conductivity, and reaction kinetics could be achieved through F functionalization . However, benefiting from the largest ionic radius, INi(OH)2 contributes the best specific capacity and morphology transformation, which is a new finding that distinguishes it from previous reports in the literature. The exploration of the interaction effect of halogens (F, INi(OH)2 , F, BrNi(OH)2 , and Cl, INi(OH)2 ) manifests that F, INi(OH)2 delivers a higher specific capacity of 200.6 mAh g-1 and an excellent rate capability of 58.2% due to the weaker electrostatic repulsion, abundant defect structure, and large layer spacing. Moreover, the F, INi(OH)2 //FeOOH@NrGO device achieves a high energy density of 97.4 Wh kg-1 and an extremely high power density of 32426.7 W kg-1 , as well as good cycling stability. This work develops a pioneering tactic for designing energy storage materials to meet various demands.

Dandelion-Like CuCo2O4@ NiMn LDH Core/Shell Nanoflowers for Excellent Battery-Type Supercapacitor

Dandelion-like CuCo₂O₄ nanoflowers (CCO NFs) with ultrathin NiMn layered double hydroxide (LDH) shells were fabricated via a two-step hydrothermal method. The prepared CuCo₂O₄@NiMn LDH core/shell nanoflowers (CCO@NM LDH NFs) possessed a high specific surface area (~181 m²·g^-1) with an average pore size of ~256 nm. Herein, the CCO@NM LDH NFs exhibited the typical battery-type electrode material with a specific capacity of 2156.53 F·g^-1 at a current density of 1 A·g^-1. With the increase in current density, the rate capability retention was 68.3% at a current density of 10 A·g^-1. In particular, the 94.6% capacity of CCO@NM LDH NFs remains after 2500 cycles at 5 A·g^-1. An asymmetric supercapacitor (ASC) with CCO@NM LDH NFs//activated carbon (AC) demonstrates a remarkable capacitance of 303.11 F·g^-1 at 1 A·g^-1 with excellent cycling stability. The coupling and synergistic effects of multi-valence transition metals provide a convenient channel for the electrochemical process, which is beneficial to spread widely within the realm of electrochemical energy storage.

Two-step electrodeposition synthesis of iron cobalt selenide and nickel cobalt phosphate heterostructure for hybrid supercapacitors

Exploring novel heterostructure with multiscale nanoarchitectures and modulated electronic structure is crucial to improve the electrochemical properties of electrode materials for supercapacitors (SCs). In this study, a two-step electrodeposition approach which involves suitable efficient procedures, is leading to in-situ preparation of iron cobalt selenide (Fe0.4Co0.6Se2) @ nickel cobalt phosphate (NiCo(HPO4)2·3H2O, denoted as NiCo-P) hybrid nanostructure on carbon cloth (CC) substrate. Particularly, depositing two-dimensional (2D) NiCo-P nanosheets on the surface of Fe0.4Co0.6Se2 nanobelts results in formation of well-organized Fe0.4Co0.6Se2@NiCo-P nanocomposite with large surface area, hierarchical porous nanoarchitecture as well as numerous electroactive sites, leading to enhanced electroactivity and accelerated mass/electron transfer. Benefiting from its unique nanoarchitecture and synergistic effect of two components, the obtained free-standing Fe0.4Co0.6Se2@NiCo-P electrode demonstrates gravimetric capacity (Cm)/volumetric capacity (Cd) of 202.3 mAh/g/319.6 mAh cm-3 at 1 A g-1 and good cyclic stability (83.9% capacity retention over 5000 cycles), which are superior to those of pure Fe0.4Co0.6Se2 and NiCo-P electrodes. Impressively, it was established that an aqueous hybrid supercapacitor (HSC) based on Fe0.4Co0.6Se2@NiCo-P and rape pollen derived hierarchical porous carbon (RPHPC) achieves gravimetric energy density (Em)/volumetric energy density (Ed) of 64.4 Wh kg-1/10.7 mWh cm-3 and a long cycle life with 90.3% capacity retention over 10,000 cycles. This report offers a perspective to design selenide/phosphate heterostructure on conducting substrate for electrochemical energy storage applications.

Regulating Ni3+ contents by a cobalt doping strategy in ternary NixCo3−xAl1-LDH nanoflowers for high-performance charge storage

The Ni1Co2Al1-LDH electrode prepared by hydrothermal method delivers a high specific capacitance (728 C g−1 at 1 A g−1) and excellent capacitance retention (93.18% of initial capacitance at 30 A g−1 after 10 000 cycles).