Rational Construction of Bi2CuO12Se4 and VGCFs@Fe2O3 Composite Electrodes for High-Performance Semi-Solid-State Asymmetric Supercapacitors.

Recently, supercapacitors (SCs) are extensively explored as effective energy storage devices. Specifically, asymmetric SCs are being developed to enhance energy density using suitable materials with favorable nanostructures. This study describes the construction of a bismuth copper selenite (BCS-200) working electrode with an ultrathin nanosheet (UTNS) architecture. This morphology is achieved using a low-cost electrodeposition (ED) method, followed by annealing. The impact of ED time on the development of morphology is studied by synthesizing comparative electrodes simultaneously. The optimized BCS-200 electrode prepared with a deposition time of 200 s shows higher specific capacity/capacitance (Cs/Csc) values of 330.9 mAh g-1/2206.6 F g-1 than the other synthesized electrodes (BCS-100, BCS-150, BCS-250, and BCS-300). Besides, a vapor-grown carbon fiber (VGCF)-added Fe2O3 composite coated on nickel foam (NF) is developed as a negative electrode. The VGCFs@Fe2O3/NF electrode exhibits the (Cs/Csc) values of 183.5 mAh g-1/734.4 F g-1, which is associated with ultra-high cycling stability. In addition, the fabricated BCS-200 and VGCFs@Fe2O3/NF electrodes are combined to construct a wearable semi-solid-state asymmetric SC (SSASC) with an energy density (Ed) of 20.5 Wh kg-1 and a cycling stability of 91.7% over 40000 charge/discharge cycles. Furthermore, the real-time applicability of the SSASC is verified by powering it in practical applications.

Multifunctional metal selenide-based materials synthesized via a one-pot solvothermal approach for electrochemical energy storage and conversion applications.

Highly-efficient electroactive materials with distinctive electrochemical features, along with suitable strategies to prepare hetero-nanoarchitectures incorporating two or more transition metal selenides, are currently required to increase charge storage ability. Herein, a one-pot solvothermal approach is used to develop iron-nickel selenide spring-lawn-like architectures (FeNiSe SLAs) on nickel (Ni) foam. The porous Ni foam scaffold not only enables the uniform growth of FeNiSe SLAs but also serves as an Ni source. The effect of reaction time on their morphological and electrochemical properties is investigated. The FeNiSe-15 h electrode shows high areal capacity (493.2 µA h cm-2) and superior cycling constancy. The as-assembled aqueous hybrid cell (AHC) demonstrates high areal capacity and a decent rate capability of 59.4% (50 mA cm-2). The AHC exhibits good energy and power densities, along with excellent cycling stability. Furthermore, to confirm its practicability, the AHC is employed to drive portable electronic appliances by charging it with wind energy. The electrocatalytic activity of FeNiSe-based materials to complete the oxygen evolution reaction (OER) is explored. Among them, the FeNiSe-15 h catalyst shows good OER performance at a current density of 50 mA cm-2. This general synthesis approach may initiate a strategy of advanced metal selenide-based materials for multifunctional applications.

Unraveling CoNiP-CoP2 3D-on-1D Hybrid Nanoarchitecture for Long-Lasting Electrochemical Hybrid Cells and Oxygen Evolution Reaction.

Evolving cost-effective transition metal phosphides (TMPs) using general approaches for energy storage is pivotal but challenging. Besides, the absence of noble metals and high electrocatalytic activity of TMPs allow their applicability as catalysts in oxygen evolution reaction (OER). Herein, CoNiP-CoP2 (CNP-CP) composite is in situ deposited on carbon fabric by a one-step hydrothermal technique. The CNP-CP reveals hybrid nanoarchitecture (3D-on-1D HNA), i.e., cashew fruit-like nanostructures and nanocones. The CNP-CP HNA electrode delivers higher areal capacity (82.8 µAh cm-2 ) than the other electrodes. Furthermore, a hybrid cell assembled with CNP-CP HNA shows maximum energy and power densities of 31 µWh cm-2 and 10.9 mW cm-2 , respectively. Exclusively, the hybrid cell demonstrates remarkable durability over 30 000 cycles. In situ/operando X-ray absorption near-edge structure analysis confirms the reversible changes in valency of Co and Ni elements in CNP-CP material during real-time electrochemical reactions.  Besides, a quasi-solid-state device unveils its practicability by powering electronic components. Meanwhile, the CNP-CP HNA verifies its higher OER activity than the other catalysts by revealing lower overpotential (230 mV). Also, it exhibits relatively small Tafel slope (38 mV dec-1 ) and stable OER activity over 24 h. This preparation strategy may initiate the design of advanced TMP-based materials for multifunctional applications.

Prussian-Blue Analogue-Derived Hollow Structured Co3 S4 /CuS2 /NiS2 Nanocubes as an Advanced Battery-Type Electrode Material for High-Performance Hybrid Supercapacitors.

The facile and cost-effective fabrication of hybrid nanostructures comprised of hollow mixed metallic chalcogenides has attracted growing interest in the development of high-performance energy storage devices. Herein, multi-component (nickel-cobalt-copper-sulfides/selenides (NCCS/NCCSe)) hollow nanocubes (HNCs) are prepared via a single-step sulfurization/selenization process. The NCCS material shows interior HNCs, and the NCCSe material exhibits slightly formed porous cubes. Both the prepared materials demonstrate higher charge storage performance than the precursor NCC NCs owing to the improved surface morphology and addition of sulfur and selenium ions. Particularly, the NCCS HNCs electrode reveals superior specific capacity (capacitance) (70.32 mAh g-1 (666.20 F g-1 ) at 5 mA cm-2 ) along with excellent cycling stability of 108.6% even after 10 000 cycles. Interestingly, the electrode delivers a good rate capability of 83.5% at a high current density of 20 mA cm-2 . The feasibility of the battery-type NCCS HNCs as a positive electrode is explored by constructing an aqueous electrochemical hybrid capacitor (AEHC). The AEHC exhibits maximum energy and power densities of 23.15 Wh kg-1 and 7899.08 W kg-1 , respectively. Remarkably, it demonstrates superior long-life cycling stability even after 10 000 cycles (120.6% retention). The suitability of AEHC for practical application is also tested by driving electronic devices.

One-Pot Hydrothermal-Derived NiS2 -CoMo2 S4 with Vertically Aligned Nanorods as a Binder-Free Electrode for Coin-Cell-Type Hybrid Supercapacitor.

Transition bimetallic sulfides are exploited as high-capacity electrode materials in energy storage devices owing to their abundant electroactive sites and relatively high electrical conductivity compared with metal oxides. Here, an in situ conversion of metal ions into NiS2 -CoMo2 S4 vertically aligned nanorod arrays on nickel foam (NS-CMS NRAs@NF) using a one-step hydrothermal technique to address the "dead-mass" limitation and multi-step preparation methods is reported. An in situ-converted NS-CMS NRAs obtained for 12 h of reaction time (NS-CMS NRAs-12 h@NF) delivers a superior areal capacity of 780 µAh cm-2 to the other NS-CMS electrodes synthesized for 6 h (543.1 µAh cm-2 ) and 18 h (636.7 µAh cm-2 ) at 7 mA cm-2 . A coin-cell-type hybrid supercapacitor (HSC) is also fabricated to unveil the practical adaptability of NS-CMS NRAs-12 h@NF electrode. Utilizing its structural and active material intriguing features, assembled coin-cell-type HSC achieves a high areal capacitance of 246.2 mF cm-2 (5 mA cm-2 ) along with maximum areal energy density (147 µWh cm-2 ) and power density (21.3 mW cm-2 ), respectively. Furthermore, the capability of coin-cell-type HSC in real-time applications is also inspected. This work promotes in situ deposition strategy to fabricate metal sulfide-based nanostructures for high-performance electrochemical capacitors.

Nanosilver-Particles Integrated Ni3 Sn2 S2 -CoS Composite as an Advanced Electrode for High Energy Density Hybrid Cell.

An ion-exchange process is a promising approach to design advanced electrode materials for high-performance energy storage devices. Herein, a nanostructured Ni3 Sn2 S2 -CoS (NSS-CS) composite is fabricated by successive hydrothermal and ion-exchange processes. Since the incorporation of redox-rich cobalt element enables the NSS-CS composite to be more electrochemically active, its impact on the electrochemical performance is therefore extensively studied. Particularly, the NSS-CS-0.2 g electrode material delivered a high areal capacity of 830.4 µAh cm-2 at 5 mA cm-2 . Additionally, a room-temperature wet-chemical approach is employed to anchor nanosilver (nAg)-particles on the NSS-CS-0.2 g (nAg@NSS-CS-0.2 g) to further exalt its electrokinetics. Consequently, the nAg@NSS-CS-0.2 g electrode shows a higher areal capacity of 948.5 µAh cm-2 (193.5 mAh g-1 ) than that of the NSS-CS-0.2 g. Furthermore, its practicability is also examined by assembling a hybrid cell. The assembled hybrid cell delivers a high areal capacity of 969.2 µAh cm-2 (49.2 mAh g-1 ) at 7 mA cm-2 and maximum areal energies and power densities of 0.784 mWh cm-2 (40.8 Wh kg-1 ) and 45 mW cm-2 (2347.4 W kg-1 ), respectively. The efficiency of the hybrid cells is also tested by harvesting solar energy, followed by energizing electronic components. This work can pave the way for significant attraction in designing advanced electrodes for energy-related fields.

Metal-Organic Framework-Derived Co3 V2 O8 @CuV2 O6 Hybrid Architecture as a Multifunctional Binder-Free Electrode for Li-Ion Batteries and Hybrid Supercapacitors.

Metal-organic frameworks (MOFs) are promising materials in diverse fields because of their constructive traits of varied structural topologies, high porosity, and high surface area. MOFs are also an ideal precursor/template to derive porous and functional morphologies. Herein, Co3 V2 O8 nanohexagonal prisms are grafted on CuV2 O6 nanorod arrays (CuV-CoV)-grown copper foam (CF) using solution-processing methods, followed by thermal treatment. Direct preparation of active material on CF can potentially eliminate electrochemically inactive and non-conductive binders, leading to improved charge-transfer rate. Furthermore, solution-processing methods are simple and cost-effective. Owing to versatile valence states and good redox activity, the vanadium-incorporated mixed metal oxides (CuV-CoV) exhibited superior electrochemical performance in lithium (Li)-ion battery and supercapacitor (SC) studies. Furthermore, hollow carbon particles (HCPs) derived from MOF particles (MOF-HCPs) are used as the anode material in SCs. A hybrid SC (HSC) fabricated with CuV-CoV and MOF-HCP materials exhibited noteworthy electrochemical properties. Moreover, a solid-state HSC (SSHSC) is constructed and its real-time feasibility is investigated by harvesting the dynamic energy of a bicycle with the help of a direct current generator. The charged SSHSCs potentially powered various electronic components.

Graphene Matrix Sheathed Metal Vanadate Porous Nanospheres for Enhanced Longevity and High-Rate Energy Storage Devices.

Rational design of anode materials comprising rich benefits of high capacity, superior rate capability, and exalted lifetime is of considerable significance in the progress of high-performance Li-ion batteries (LIBs) and supercapatteries. Herein, highly porous cobalt vanadate (Co2VO4) nanospheres encapsulated with reduced graphene oxide (rGO) nanosheets (rGO@CoV PNSs) were prepared by a facile hydrothermal method and employed as a hybrid composite-based anode material for energy storage devices. The nanocavities and porous features of CoV nanospheres, and the laminated rGO nanosheets over CoV PNSs can significantly surpass the volume changes and enhance the surface electrokinetics, respectively. With benefits of rich redox activity and constructive traits, the rGO@CoV PNSs as an electrode material in LIBs exhibited superior reversible capacity of 780.6 mAh/g after 100 cycles with remarkable rate performance. Moreover, the hybrid composite displayed an excellent reversible capacity of 531.8 mAh/g even after 1000 cycles performed at 1000 mA/g. Utilizing the synergistic features, the rGO@CoV PNSs composite was also explored as a battery-type electrode for supercapatteries. The fabricated supercapattery device with rGO@CoV PNSs and rGO demonstrated good rate performance including superior areal energy (0.048 mWh/cm2) and power (9.96 mW/cm2) densities. Therefore, the graphene sheathed metal vanadates would be an ultrahigh rate electrode candidates for energy storage devices.

Ternary MOF-Based Redox Active Sites Enabled 3D-on-2D Nanoarchitectured Battery-Type Electrodes for High-Energy-Density Supercapatteries.

Designing rationally combined metal-organic frameworks (MOFs) with multifunctional nanogeometries is of significant research interest to enable the electrochemical properties in advanced energy storage devices. Herein, we explored a new class of binder-free dual-layered Ni-Co-Mn-based MOFs (NCM-based MOFs) with three-dimensional (3D)-on-2D nanoarchitectures through a polarity-induced solution-phase method for high-performance supercapatteries. The hierarchical NCM-based MOFs having grown on nickel foam exhibit a battery-type charge storage mechanism with superior areal capacity (1311.4 µAh cm-2 at 5 mA cm-2), good rate capability (61.8%; 811.67 µAh cm-2 at 50 mA cm-2), and an excellent cycling durability. The superior charge storage properties are ascribed to the synergistic features, higher accessible active sites of dual-layered nanogeometries, and exalted redox chemistry of multi metallic guest species, respectively. The bilayered NCM-based MOFs are further employed as a battery-type electrode for the fabrication of supercapattery paradigm with biomass-derived nitrogen/oxygen doped porous carbon as a negative electrode, which demonstrates excellent capacity of 1.6 mAh cm-2 along with high energy and power densities of 1.21 mWh cm-2 and 32.49 mW cm-2, respectively. Following, the MOF-based supercapattery was further assembled with a renewable solar power harvester to use as a self-charging station for various portable electronic applications.

Synergistic Effects of Cobalt Molybdate@Phosphate Core-Shell Architectures with Ultrahigh Capacity for Rechargeable Hybrid Supercapacitors.

Designing binder-free and core-shell-like electrode materials with synergistic effects has attracted widespread attention for the development of high energy density hybrid supercapacitors (HSCs). Herein, binder-free cobalt molybdate nanosheet-laminated cobalt phosphate micropetals on nickel foam (CoM NS@CoP/NF) were facilely prepared for use as an effective battery-type electrode in HSCs. With the multifunctional features, the rationally combined core-shell-like CoM NS@CoP/NF electrode exhibited a maximum capacity of 886.8 µA h/cm2 at a current density of 5 mA/cm2 with a good rate capability of 64.2% and cycling stability of 87.4% (after 10 000 cycles). The high electrochemical performance of the hybrid composite could be attributed to the synergistic effects of hierarchical architectures and large accessible electroactive area, which facilitates the fast electron/transportation within the active material and accelerates the redox chemistry process. Utilizing the superior energy-storage properties, a pouch-type HSC was fabricated with core-shell-like CoM NS@CoP-6 h architectures as a battery-type electrode and activated carbon as a capacitive-type electrode in an aqueous alkaline electrolyte. The miniature hybrid device exhibited maximum energy and power densities of 0.44 mW h/cm2 and 40.35 mW/cm2, respectively, with good cycling stability. Moreover, the HSCs can energize various portable electronic equipments, which demonstrates their suitability for real-time applications.

An Integrated Approach Toward Renewable Energy Storage Using Rechargeable Ag@Ni0.67 Co0.33 S-Based Hybrid Supercapacitors.

Self-powered charging systems in conjunction with renewable energy conversion and storage devices have attracted promising attention in recent years. In this work, a prolific approach to design a wind/solar-powered rechargeable high-energy density pouch-type hybrid supercapacitor (HSC) is proposed. The pouch-type HSC is fabricated by engineering nature-inspired nanosliver (nano-Ag) decorated Ni0.67 Co0.33 S forest-like nanostructures on Ni foam (nano-Ag@NCS FNs/Ni foam) as a battery-type electrode and porous activated carbon as a capacitive-type electrode. Initially, the core-shell-like NCS FNs/Ni foam is prepared via a single-step wet-chemical method, followed by a light-induced growth of nano-Ag onto it for enhancing the conductivity of the composite. Utilizing the synergistic effects of forest-like nano-Ag@NCS FNs/Ni foam as a composite electrode, the fabricated device shows a maximum capacitance of 1104.14 mF cm-2 at a current density of 5 mA cm-2 and it stores superior energy and power densities of 0.36 mWh cm-2 and 27.22 mW cm-2 , respectively along with good cycling stability, which are higher than most of previous reports. The high-energy storage capability of HSCs is further connected to wind fans and solar cells to harvest renewable energy. The wind/solar charged HSCs can effectively operate various electronic devices for a long time, enlightening its potency for the development of sustainable energy systems.

Hierarchically Designed Ag@Ce6Mo10O39 Marigold Flower-Like Architectures: An Efficient Electrode Material for Hybrid Supercapacitors.

We facilely prepared silver nanoparticle-decorated Ce6Mo10O39 marigold flower-like structures (Ag NPs@CM MFs) for use as an effective positive material in hybrid supercapacitors (HSCs). With the aid of ethylenediaminetetraacetic acid (EDTA) as a chelating agent, self-assembled CM MFs were synthesized by a single-step hydrothermal method. When the electrochemical properties were tested in an aqueous alkaline electrolyte, the synthesized CM MFs with 0.15 g of EDTA exhibited a relatively high charge storage property (55.3 µA h/cm2 at 2 mA/cm2) with a battery-type redox behavior. The high capacity performance is mainly because of the large surface area of the CM MFs, and the hierarchically connected nanoflakes provide wide open wells for rapid accessibility of electrolyte ions and enable fast transportation of electrons. A further improvement in electrochemical performance was achieved (62 µA h/cm2 at 2 mA/cm2) by decorating Ag NPs on the surface of the CM MFs (i.e., Ag NPs@CM MFs), which is attributed to the increased electric conductivity. Considering the synergistic effect and the high electrochemical activity, Ag NPs@CM MFs were further employed as an effective positive electrode for the fabrication of pouch-type HSC with porous carbon (negative electrode) in an alkaline electrolyte. The HSC exhibited a high cell potential (1.5 V) with maximum energy and power densities of 0.0183 mW h/cm2 and 10.237 mW/cm2, respectively. The potency of HSC in practical applications was also demonstrated by energizing red and yellow light-emitting diodes as well as a three-point pattern torch light.