Large-scale synthesis of Ni(OH)2/peach gum derived carbon nanosheet composites with high energy and power density for battery-type supercapacitor

Microwave-Assisted Hierarchically Grown Flake-like NiCo Layered Double Hydroxide Nanosheets on Transitioned Polystyrene towards Triboelectricity-Driven Self-Charging Hybrid Supercapacitors

Recently, there is a need to explore the utilization of various heterostructures using the designed nanocomposites and tuning the surfaces of electrodes for improving the electrochemical performance of supercapacitors (SC). In this work, a novel approach is successfully employed through a facile two-step synthetic route with the assistance of a microwave for only 1 min. Depending on the glass transition of a polystyrene (PS) substrate and electrochemical deposition (ECD) of electroactive Ni-Co layered double hydroxides (LDHs), a hierarchically designed flake-like morphology can be readily prepared to enhance the surface-active sites, which allows a rhombohedral Ni-Co LDHs electrode to obtain superior electrochemical properties. Further, the interactions between electrode and electrolyte during the diffusion of ions are highly simplified using multiple enhanced electroactive sites and shorter pathways for electron transfer. The unique surface architecture of the PS substrate and the synergistic effect of the bimetallic components in Ni-Co LDHs enable this substrate to obtain desired electrochemical activity in charge storage systems. The optimized MWC Co_0.5Ni_0.5 electrode exhibited an areal capacity of 100 µAh/cm² at a current density of 1 mA/cm² and a remarkable capacity retention of 91.2% over 5000 continuous charging and discharging cycles due to its remarkable synergistic effect of abundant faradaic redox reaction kinetics. The HSC device is assembled with the combination of optimized MWC Co_0.5Ni_0.5 and activated carbon as a positive and negative electrode, respectively. Further, the electrochemical test results demonstrated that MWC Co_0.5Ni_0.5 //AC HSC device showed a high areal capacitance of 531.25 mF/cm² at a current density of 5 mA/cm². In addition, the fabricated an aqueous HSC device showed a power density of 16 mW/cm² at an energy density of 0.058 mWh/cm², along with the remarkable capacity retention of 82.8% even after 10,000 continuous charging and discharging cycles. Moreover, the assembled hybrid supercapacitor (HSC) device is integrated with a triboelectric nanogenerator (TENG) for the development of energy conversion and storage systems. Not only an extensive survey of materials but also an innovative solution for recent progress can confirm the wide range of potential SC applications. Remarkably, this study is a new way of constructing self-powered energy storage systems in the field of sustainable wearable electronics and future smart sensing systems.

Flower-like Ni3Sn2@Ni3S2 with core-shell nanostructure as electrode material for supercapacitors with high rate and capacitance

To enhance the specific capacitance as well as maintain satisfactory rate performance of nickel hydroxide and nickel sulfide, in this work, the ultra-fine nickel-tin nanoparticles with high conductivity are selected to synthesize Ni₃Sn₂@Ni(OH)₂ and Ni₃Sn₂@Ni₃S₂ nanoflowers. Alloy as the core material improves the electrical conductivity of the composite, and the nanosheets prepared by electrochemical corrosion effectively avoid aggregation as well as increase the active sites of the electrode material. By adjusting the corrosion time, the Ni₃Sn₂@Ni(OH)₂ with better morphology displays a high specific capacitance (1277.37C g^-1 at 1 A g^-1) and good rate performance (1028C g^-1 at 20 A g^-1). After sulfurization, the optimal Ni₃Sn₂@Ni₃S₂ perfectly retains the morphological characterizations of the precursor and exhibits ultra-high specific capacitance (1619.02C g^-1 at 1 A g^-1) as well as outstanding rate performance (1312C g^-1 at 20 A g^-1). The samples before and after vulcanization both have the excellent electrochemical properties, which is attributed to the rational design and construction of the alloy-based core-shell nanostructures. Besides, the all-solid-state hybrid supercapacitor (HSC) is assembled by Ni₃Sn₂@Ni₃S₂ as the positive electrode and activated carbon as the negative electrode, displaying outstanding energy density of 70.54 Wh kg^-1 at 808.67 W kg^-1 and excellent cycling stability (93.21 % after 10,000 cycles). This work provides a novel ingenuity for synthesizing high-performance supercapacitor electrodes.

Template-Free Preparation of α-Ni(OH)2 Nanosphere as High-Performance Electrode Material for Advanced Supercapacitor

Although it is one of the promising candidates for pseudocapacitance materials, Ni(OH)₂ is confronted with poor specific capacitance and inferior cycling stability. The design and construction of three-dimensional (3D) nanosphere structures turns out to be a valid strategy to combat these disadvantages and has attracted tremendous attention. In this paper, a 3D α-Ni(OH)₂ nanosphere is prepared via a facile and template-free dynamic refluxing approach. Significantly, the α-Ni(OH)₂ nanosphere possesses a high specific surface area (119.4 m²/g) and an abundant porous structure. In addition, the as-obtained α-Ni(OH)₂ electrodes are investigated by electrochemical measurements, which exhibit a high specific capacitance of 1243 F/g at 1 A/g in 6 M KOH electrolyte and an acceptable capacitive retention of 40.0% after 1500 charge/discharge cycles at 10 A/g, which can be attributed to the sphere’s unique nanostructure. Furthermore, the as-assembled Ni(OH)₂-36//AC asymmetric supercapacitor (ASC) yields a remarkable energy density of 26.50 Wh/kg, with a power density of 0.82 kW/kg. Notably, two ASCs in series can light a 2.5 V red lamp sustainably for more than 60 min, as well as power an LED band with a rated power of 25 W. Hence, this 3D α-Ni(OH)₂ nanosphere may raise great potential applications for next-generation energy storage devices.

A review on peach gum polysaccharide: Hydrolysis, structure, properties and applications

To achieve sustainable development, increasing attention has been paid to the utilization of renewable polysaccharides extracted from plant gum instead of synthetic materials. Peach gum polysaccharide (PGP) is a typical polysaccharide, which can be readily obtained by hydrolysis of peach gum, one of the abundant plant gums in the world. In the past decade, the research on the hydrolysis, structure, properties and applications of PGP has aroused great interest. The PGP with highly branched macromolecular structure shows remarkable merits of numerous functional groups, excellent water solubility, good biocompatibility, favorable emulsifying property, fine antioxidant and antibacterial activity, and low cost. The application of PGP has expanded from the pharmaceutical field to the fields of food, adsorbents, functional carbon materials, binders and gel materials. This review systematically introduces the research progress of PGP, as well as the opportunities and challenges faced by PGP in scientific research and practical application.

Core-shell Ni1.5Sn@Ni(OH)2 nanoflowers as battery-type supercapacitor electrodes with high rate and capacitance

Poor conductivity and aggregation of two-dimensional Ni(OH)₂ nanosheets hinder their extensive applications in supercapacitors. In the current study, a core-shell nanoflower composite is successfully synthesized using a high conductivity Ni_1.5Sn alloy and Ni(OH)₂ nanosheets via a facile two-step hydrothermal reaction. The alloy material enhances the conductivity of the sample and promotes electron transport for Ni(OH)₂. The as-prepared core-shell structure effectively restrains the clustering of nanosheets and improves the specific surface area of active materials. The optimized NS@NL-3 displays an outstanding specific capacitance (1002.2C g^-1 at 1 A g^-1) and satisfactory capacitance retention rate (80.63% at 20 A g^-1) by adjusting the coating amount of Ni(OH)₂ nanosheets, which is significantly higher compared with the performance of pure Ni(OH)₂ (609.6C g^-1 at 1 A g^-1 and 55.64% at 20 A g^-1). The all-solid-state hybrid supercapacitor (HSC) is fabricated with activated carbon (AC) as the negative electrode and NS@NL-3 as the positive electrode, which shows a high energy density of 57.4 Wh kg^-1 at 803.6 W kg^-1 as well as a superior cycling stability (88.45 % after 10,000 cycles). Experiment shows that 42 LEDs are effortlessly lit by two series-wound solid-state HSC devices, which indicates its high potential for practical applications.

Construction of hierarchical sea urchin-like manganese substituted nickel cobaltite@tricobalt tetraoxide core-shell microspheres on nickel foam as binder-free electrodes for high performance supercapacitors

Construction of binder-free electrodes with hierarchical core-shell nanostructures is considered to be an effective route to promote the electrochemical performance of supercapacitors. In this work, the porous Ni_0.5Mn_0.5Co₂O₄ nanoflowers anchored on nickel foam are utilized as framework for further growing Co₃O₄ nanowires, resulting in the hierarchical sea urchin-like Ni_0.5Mn_0.5Co₂O₄@Co₃O₄ core-shell microspheres on nickel foam. Owing to the advantages brought by unique porous architecture and synergistic effect of the multi-component composites, the as-prepared electrode exhibits a high specific capacitance (931 F/g at 1 A/g), excellent rate performance (77% capacitance retention at 20 A/g) and outstanding cycle stability (92% retention over 5000 cycles at 5 A/g). Additionally, the assembled Ni_0.5Mn_0.5Co₂O₄@Co₃O₄//AC (activated carbon) asymmetric supercapacitor achieves a high energy density (50 Wh/kg at 750 W/kg) and long durability (88% retention after 5000 cycles).

Development of vertically aligned trimetallic Mg-Ni-Co oxide grass-like nanostructure for high-performance energy storage applications

Direct growth of nanostructured trimetallic oxide on substrate is considered as one of the promising electrode fabrication for high-performance hybrid supercapacitors. Herein, binder-free one-dimensional grass-like nanostructure was constructed on nickel foam by using electrodeposition approach. The admirable enhancement in rate capability was observed by the substitution of Mg and Ni in cobalt oxide crystallite. The prepared nickel cobalt oxide (NCO) and cobalt oxide (CO) electrode exhibited a rate capability of 57% and 58% (2 to 10 A g^-1) respectively. Interestingly, the rate capability was increased to 87% by the substitution of Mg and Ni simultaneously. The novel vertically aligned trimetallic Mg-Ni-Co oxide (MNCO) grass-like nanostructure electrode exhibited a high specific capacity of 846 C g^-1 at 2 A g^-1_, retained 97.3% specific capacity and showed an outstanding coulombic efficiency of 99% after 10,000 charge-discharge cycles. Moreover, we assembled hybrid supercapacitor (HSC) device for practical applications by using MNCO and activated carbon (AC) as the positive and negative electrode materials, respectively. HSC device exhibited a high specific capacity of 144 C g^-1 at 0.5 A g^-1. The high energy density of 31.5 Wh kg^-1 and the power density of 7.99 kW kg^-1 were achieved. All these interesting and attractive results demonstrate the significance of the vertically aligned electrode material towards practical applications.