Redox Materials Research Articles

Exploring the Synergistic Effects of Dual‐Layer Electrodes for High Power Li‐Ion Batteries

AbstractThe electrification of the transport sector has created an increasing demand for lithium‐ion batteries that can provide high power intermittently while maintaining a high energy density. Given the difficulty in designing a single redox material with both high power and energy density, electrodes based on composites of several electroactive materials optimized for power or capacity are being studied extensively. Among others, fast‐charging LiFePO4 and high energy Li(NixMnyCoz)O2 are commonly employed in industrial cell manufacturing. This study focuses on comparing different approaches to combining these two active materials into a single electrode. These arrangements were compared using standard electrochemical (dis)charge procedures and using synchrotron X‐ray fluorescence to identify variations in solution concentration gradient formation. The electrochemical performance of the layered electrodes with the high‐power material on top is found to be enhanced relative to its blended electrode counterpart when (dis)charged at the same specific currents. These findings highlight dual‐layer lithium‐ion batteries as an inexpensive way of increasing energy and power density of lithium‐ion batteries as well as a model system to study and exploit the synergistic effects of blended electrodes.

Recent Developments in Ceria-Driven Solar Thermochemical Water and Carbon Dioxide Splitting Redox Cycle

Metal oxide (MO) based solar thermochemical H2O (WS) and CO2 splitting (CDS) is one of the most promising and potential-containing processes that can be used to produce H2 and syngas (liquid fuel precursor). Several non-volatile and volatile MOs were considered redox materials for the solar-driven WS and CDS operation. Among all the examined redox materials, based on their high O2 storage capacity, faster oxidation kinetics, and good stability, ceria and doped ceria materials are deemed to be one of the best alternatives for the operation of the thermochemical redox reactions associated with the WS and CDS. Pure ceria was used for solar fuel production for the first time in 2006. A review paper highlighting the work done on the ceria-based solar thermochemical redox WS and CDS cycle from 2006 until 2016 is already published elsewhere by the author. This review paper presents all the significant findings reported in applying pure ceria and doped ceria materials for the WS and CDS by research teams worldwide.

Al- and Cr-doped Co3O4/CoO redox materials for thermochemical energy storage in concentrated solar power plants

The redox system of Co3O4/CoO is very promising for the thermochemical energy storage systems coupled to concentrated solar power plants because of its high energy storage density and reversibility. Nevertheless, the practical application of Co3O4/CoO system is limited by thermal hysteresis of the redox reaction and material sintering. Here, we synthesized Co-based metal oxides doped with Al and Cr, and studied the influence of the doping of these two metal elements on the thermochemical properties and sintering resistance of the pure Co3O4/CoO system. Both Al and Cr doping narrows the thermal hysteresis of the Co3O4/CoO system. In particular, when the molar doping rate of Al is 10%, the thermal hysteresis of Co–Al oxides is only 4.02 °C, which is much narrower than that of pure Co3O4, and the increase of its oxidation temperature also means that a higher level of thermal energy can be released during oxidation. In the redox cycle, the addition of Al inhibits material sintering and the formation of a loose porous structure facilitates the oxidation, ensuring the reversibility of the redox reaction. The 10% Al–Co honeycomb shows stable conversion behavior with an average conversion of 77.75% in 15 redox cycles. Co–Al oxides exhibit excellent oxidative exothermic characteristics and long-term cycle stability, making them suitable for efficient thermochemical energy-storage processes.

High-entropy spinel oxide (Fe0.2Mg0.2Mn0.1Al0.3Cr0.2)3O4 as a highly active and stable redox material for methane driven solar thermochemical water splitting

Solar thermochemical H2O splitting has attained wide attention as a promising solution for hydrogen production. However, it remains a daunting challenge to produce hydrogen with high kinetics and stability for the oxide materials at lower temperature because of insufficient active sites for H2O activation and splitting. Herein, we report a high-entropy spinel oxide that consists of five cations (HEO) and can highly-effectively thermochemically split H2O to H2 with ultrahigh production rate and productivity of 182.9 mL min-1 g-1 and 68.5 mL g-1, respectively, several times higher than state-of-the-art materials via a two-step cycle process with methane driven reduction. High-entropy effect facilitated the preservation of single-phase structure even at large amount of oxygen converted (almost 70 mL g-1), which promoted the exsolution and stabilization of substantial Fe0 nanoparticles (20–30 nm vs. 100 nm) and their dissolution into spinel structure during redox process, resulting in extensive metal-oxide interfaces with metal-oxygen vacancy pairs responsible for the efficient and stable water splitting. Such findings provide a class of viable material with high configurational entropy for efficient hydrogen generation.

Chemical Learning Module Based on Multiple Representations of Redox Materials

This study aims to create and evaluate the effectiveness of a chemistry learning module based on various redox material representations. Research and development (R&D) is the methodology used in this research: using a 4D model. It consists of defining, designing, developing, and disseminating stages. The research was carried out until the development phase. The quality of the module was assessed by material experts, media experts, and reviewers (chemistry educators). The respondents are 32 students in first grade of Senior High School Science class. Quality assessment and student responses were made using a Likert and Guttman scale questionnaire sheet. The result shows that the percentage of objectives found by validating all aspects of the module's content by media, reviewers, and chemistry educators experts are 91.6%, 94.7%, and 81.25%, respectively, with excellent categories, and students responded positively to the module. The module is considered helpful as a learning media for redox topics.

Thermodynamic screening of candidate ceria and perovskite systems as potential oxygen carrier materials for chemical looping water gas shift

Methane reforming and gasification processes are valuable pathways toward hydrogen production, and currently they represent nearly 79% of the worldwide hydrogen production market share. Chemical looping-water gas shift (CL-WGS) is a promising downstream process that can be integrated with reforming and gasification reactors and utilizes redox active metal oxides as oxygen exchange materials to produce separate streams of H2 and CO2. Thus, this technology can enable the production of high-purity hydrogen coupled with carbon capture without the need for an additional CO2 separation system.Although a number of redox-active metal oxides have been proposed in the literature as viable candidates for CL-WGS, the majority are based on stoichiometric metal oxides. However, non-stoichiometric oxides, which have the benefit of stability, rapid kinetics, and thermodynamic tunability, have only been proposed a handful of times. And of the prior proposed non-stoichiometric materials, none of the so called “water splitting” redox materials of the solar thermochemical H2O splitting (STCH) fields have been discussed for CL-WGS applications, despite their potentially favorable thermodynamic properties. In this research, we have identified 13 potential oxygen carrier materials and screened these for CL-WGS viability based on a simplified closed-system thermodynamic analysis. Ceria (CeO2-δ), CZO20 (Ce0.8Zr0.2O2-δ), and LSMA4060 (La0.6Sr0.4Mn0.4Al0.6O3-δ) are identified to have the most suitable properties in terms of operating temperatures, specific H2 yields, and conversions of syngas, during reduction, and steam, during oxidation. Results show that CZO20 and LSMA4060 have especially excellent reduction and oxidation extents at relatively low operating temperatures. For example, CZO20 and LSMA4060 have 85% syngas and steam conversions when cycled between 485-912 and 100–635 °C, respectively. Results show that only CZO20 is viable for isothermal operation, but higher temperatures are required; at 1023 °C, syngas and steam conversions are 80 and 12%.

Defective core–shell NiCo2S4/MnO2 nanocomposites for high performance solid-state hybrid supercapacitors

The roles of oxygen vacancies to enhance the electrochemical performance were not clearly explained in comprehensive research. Herein, the vertically oriented NiCo2S4/MnO2 core–shell nanocomposites are in situ grown on the nickel foam (NF) surface and activated by oxygen vacancy engineering via a chemical reduction method. The scanning electron microscope (SEM) and transmission electron microscope (TEM) results show the shell-MnO2 is well coated on the core-NiCo2S4. The hierarchical core–shell nanostructures synergistically increase conductivity and provide rich faradaic redox chemical reactions. Moreover, the density functional theory (DFT) calculations further indicate that the electronic properties and structure properties in NiCo2S4/MnO2 electrode of reduction for 60 min (NiCo2S4/MnO2-60) are effectively adjusted by introducing oxygen vacancies. Impressively, the NiCo2S4/MnO2-60 electrode delivers substantially appreciable areal capacity of 2.13 mAh·cm−2 couple with superior rate capability. The as-prepared high-performance electrode material can assemble into solid-state hybrid supercapacitor. The fabricated NiCo2S4/MnO2-60//AC device exhibits an exceptional energy density of 43.16 Wh·kg−1 at a power density of 384.21 W·kg−1 and satisfactory cyclic stability of 92.1 % at current density of 10 mA·cm−2 after 10,000 cycles. In general, the work demonstrates the significance of NiCo2S4/MnO2-60 as a highly redox active electrode material for future practical application in supercapacitors.

Efficient lithium extraction using redox-active Prussian blue nanoparticles-anchored activated carbon intercalation electrodes via membrane capacitive deionization

Global demand for lithium (Li) resources has dramatically increased due to the demand for clean energy, especially the large-scale usage of lithium-ion batteries in electric vehicles. Membrane capacitive deionization (MCDI) is an energy and cost-efficient electrochemical technology at the forefront of Li extraction from natural resources such as brine and seawater. In this study, we designed high-performance MCDI electrodes by compositing Li+ intercalation redox-active Prussian blue (PB) nanoparticles with highly conductive porous activated carbon (AC) matrix for the selective extraction of Li+. Herein, we prepared a series of PB-anchored AC composites (AC/PB) containing different percentages (20%, 40%, 60%, and 80%) of PB by weight (AC/PB-20%, AC/PB-40%, AC/PB-60%, and AC/PB-80%, respectively). The AC/PB-20% electrode with uniformly anchored PB nanoparticles over AC matrix enhanced the number of active sites for electrochemical reaction, promoted electron/ion transport paths, and facilitated abundant channels for the reversible insertion/de-insertion of Li+ by PB, which resulted in stronger current response, higher specific capacitance (159 F g−1), and reduced interfacial resistance for the transport of Li+ and electrons. An asymmetric MCDI cell assembled with AC/PB-20% as cathode and AC as anode (AC//AC-PB20%) displayed outstanding Li+ electrosorption capacity of 24.42 mg g−1 and a mean salt removal rate of 2.71 mg g min−1 in 5 mM LiCl aqueous solution at 1.4 V with high cyclic stability. After 50 electrosorption-desorption cycles, 95.11% of the initial electrosorption capacity was retained, reflecting its good electrochemical stability. The described strategy demonstrates the potential benefits of compositing intercalation pseudo capacitive redox material with Faradaic materials for the design of advanced MCDI electrodes for real-life Li+ extraction applications.

Impact of Faradaic Interlayer Confinement and Carbon-Centered Macrostructure Designs for Ion Capture and the Recovery of Elements.

Environmental protection associated with renewable energy is among the most critical challenges for translational ion-capture based on capacitive storage of ions in electrical double layers at the interface of electrode and electrolyte. Electric double-layer capacitance with charge induction and faradaic pseudo-capacitance with charge transfer classifies the capacitance of the electrochemical interface. The electrochemical interface in most energy technologies involves porous and pseudocapacitive redox materials that offer varying degrees of electrolyte confinement. In this review, we discuss the factors affecting water desalination, such as the effect of nanopores for ion capture, the ion sieving effect, the effect of hydration energy, and hydration radius in the carbon sub-nanometer pore. Moreover, the surface phenomena of electrodes, including carbon corrosion, and the potential of zero charge to control the oxidation of carbon electrodes are explained along with protection mechanisms. The various capacitive deionization (CDI) operations and the corresponding electrochemical cell technologies are briefly introduced, including the significance of double-layer charging materials with faradaic intercalation, which suffer less from co-ion expulsion. Finally, we revisit the effects of various nanoarchitectures and the construction of capacitive deionization electrodes for clean water technology.

Neural network and experimental thermodynamics study of YCrO3-δ for efficient solar thermochemical hydrogen production

ABO3-type perovskites have been demonstrated as promising redox materials for solar thermochemical H2 production. In this work, a new energy material screening method based on the neural network system is designed as a feasible way to search for promising H2 production materials. The predicted oxygen vacancy formation energy of the selected YCrO3-δ is 4.199 eV, hinting excellent H2 production potential. Thermogravimetric analysis shows that the doping of Zr into YCrO3-δ improves oxygen formation capacity, leading to the maximum δ of 0.106. The molar enthalpy and entropy of YCr0.75Zr0.25O3-δ have the positive relationship with δ, and the maximum values of which are 273.7 kJ mol−1 and 164.9 J mol−1 K−1 respectively. Based on the equilibrium thermodynamic principle, the peak H2 yield is predicted to be 444.6 μmol g−1. Considering material kinetic limitation, gas-solid heat recovery and parameter sensitivity, the maximum H2 production efficiency of YCr0.75Zr0.25O3-δ is 17.3%. The combination of neural network and material thermodynamics provides a new pathway to design promising H2 production materials, and the screened YCrO3-δ presents excellent solar thermochemical H2 production capacity.

Thermochemical Activity of Single- and Dual-Phase Oxide Compounds Based on Ceria, Ferrites, and Perovskites for Two-Step Synthetic Fuel Production.

This study focuses on the generation of solar thermochemical fuel (hydrogen, syngas) from CO2 and H2O molecules via two-step thermochemical cycles involving intermediate oxygen-carrier redox materials. Different classes of redox-active compounds based on ferrite, fluorite, and perovskite oxide structures are investigated, including their synthesis and characterization associated with experimental performance assessment in two-step redox cycles. Their redox activity is investigated by focusing on their ability to perform the splitting of CO2 during thermochemical cycles while quantifying fuel yields, production rates, and performance stability. The shaping of materials as reticulated foam structures is then evaluated to highlight the effect of morphology on reactivity. A series of single-phase materials including spinel ferrite, fluorite, and perovskite formulations are first investigated and compared to state-of-the-art materials. NiFe2O4 foam exhibits a CO2-splitting activity similar to its powder analog after reduction at 1400 °C, surpassing the performance of ceria but with much slower oxidation kinetics. On the other hand, although identified as high-performing materials in other studies, Ce0.9Fe0.1O2, Ca0.5Ce0.5MnO3, Ce0.2Sr1.8MnO4, and Sm0.6Ca0.4Mn0.8Al0.2O3 are not found to be attractive candidates in this work (compared with La0.5Sr0.5Mn0.9Mg0.1O3). In the second part, characterizations and performance evaluation of dual-phase materials (ceria/ferrite and ceria/perovskite composites) are performed and compared to single-phase materials to assess a potential synergistic effect on fuel production. The ceria/ferrite composite does not provide any enhanced redox activity. In contrast, ceria/perovskite dual-phase compounds in the form of powders and foams are found to enhance the CO2-splitting performance compared to ceria.

Longevous Sodium Metal Anodes with High Areal Capacity Enabled by 3D-Printed Sodiophilic Monoliths.

Sodium metal anode, featured by favorable redox voltage and material availability, offers a feasible avenue toward high-energy-density devices. However, uneven metal deposition and notorious dendrite proliferation synchronously hamper its broad application prospects. Here, a three-dimensional (3D) porous hierarchical silver/reduced graphene oxide (Ag/rGO) microlattice aerogel is devised as a sodiophilic monolith, which is realized by a direct ink writing 3D printing technology. The thus-printed Na@Ag/rGO electrode retains a durable cycling lifespan over 3100 h at 3.0 mA cm-2/1.0 mAh cm-2, concurrently harvesting a high average Coulombic efficiency of 99.80%. Impressively, it can be cycled for 340 h at a stringent condition of 6.0 mA cm-2 with a large areal capacity of 60.0 mAh cm-2 (∼1036.31 mAh g-1). Meanwhile, the well-regulated Na ion flux and uniform deposition kinetics are systematically probed by comprehensive electroanalytical analysis and theoretical simulations. As a result, assembled Na metal full battery delivers a long cycling sustainability over 500 cycles at 100 mA g-1 with a low per-cycle decay of 0.85%. The proposed strategy might inspire the construction of high-capacity Na metal anodes with appealing stability.

Photochromic Polyoxoniobates with Photoinduced “D‐f‐A” Electron Transfer Mechanism

AbstractCompounds with redox activities have appealing applications in catalytic, electronic and magnetic properties, but the redox inert of polyoxoniobates (PONbs) significantly limits their applications for a long time. In this work, we are able to integrate organophosphate and lanthanide cluster into PONb to create the first family of inorganic‐organic hybrid organophosphate‐Ln‐PONb composite clusters. These novel species not only present the first family of redox active PONbs that can be reduced to form long‐lived “heteropoly blues” under ambient conditions, but also a new photochromic system. More importantly, the analyses of the electronic configurations and photochromic properties for a series of designed proof‐of‐concept PONbs models allow us to discover a D‐f‐A electron transfer mechanism, that is, photoinduced electron is transferred from a photosensitive organophosphate electron donor (D) to the NbV electron acceptor (A) through the unoccupied 4 f‐orbitals of Ln (f). This work paves the way for developing diverse PONb‐based redox materials and expanding the possibility of the applications of PONbs in the redox chemistry.

Photochromic Polyoxoniobates with Photoinduced "D-f-A" Electron Transfer Mechanism.

Compounds with redox activities have appealing applications in catalytic, electronic and magnetic properties, but the redox inert of polyoxoniobates (PONbs) significantly limits their applications for a long time. In this work, we are able to integrate organophosphate and lanthanide cluster into PONb to create the first family of inorganic-organic hybrid organophosphate-Ln-PONb composite clusters. These novel species not only present the first family of redox active PONbs that can be reduced to form long-lived "heteropoly blues" under ambient conditions, but also a new photochromic system. More importantly, the analyses of the electronic configurations and photochromic properties for a series of designed proof-of-concept PONbs models allow us to discover a D-f-A electron transfer mechanism, that is, photoinduced electron is transferred from a photosensitive organophosphate electron donor (D) to the NbV electron acceptor (A) through the unoccupied 4f-orbitals of Ln (f). This work paves the way for developing diverse PONb-based redox materials and expanding the possibility of the applications of PONbs in the redox chemistry.

A Review of Oxygen Carrier Materials and Related Thermochemical Redox Processes for Concentrating Solar Thermal Applications.

Redox materials have been investigated for various thermochemical processing applications including solar fuel production (hydrogen, syngas), ammonia synthesis, thermochemical energy storage, and air separation/oxygen pumping, while involving concentrated solar energy as the high-temperature process heat source for solid-gas reactions. Accordingly, these materials can be processed in two-step redox cycles for thermochemical fuel production from H2O and CO2 splitting. In such cycles, the metal oxide is first thermally reduced when heated under concentrated solar energy. Then, the reduced material is re-oxidized with either H2O or CO2 to produce H2 or CO. The mixture forms syngas that can be used for the synthesis of various hydrocarbon fuels. An alternative process involves redox systems of metal oxides/nitrides for ammonia synthesis from N2 and H2O based on chemical looping cycles. A metal nitride reacts with steam to form ammonia and the corresponding metal oxide. The latter is then recycled in a nitridation reaction with N2 and a reducer. In another process, redox systems can be processed in reversible endothermal/exothermal reactions for solar thermochemical energy storage at high temperature. The reduction corresponds to the heat charge while the reverse oxidation with air leads to the heat discharge for supplying process heat to a downstream process. Similar reversible redox reactions can finally be used for oxygen separation from air, which results in separate flows of O2 and N2 that can be both valorized, or thermochemical oxygen pumping to absorb residual oxygen. This review deals with the different redox materials involving stoichiometric or non-stoichiometric materials applied to solar fuel production (H2, syngas, ammonia), thermochemical energy storage, and thermochemical air separation or gas purification. The most relevant chemical looping reactions and the best performing materials acting as the oxygen carriers are identified and described, as well as the chemical reactors suitable for solar energy absorption, conversion, and storage.

Strategic co-doping of ceria for improved oxidation kinetics in solar thermochemical fuel production

La and Yb were incorporated as co-doping elements into Zr-doped ceria to investigate the influence of doping ions by means of ionic radius and valence on the ceria crystal lattice and potentially on thermodynamic and kinetic properties relevant to solar-driven two-step thermochemical CO2 splitting. Both Zr–La and Zr–Yb co-doped ceria clearly exhibited better reduction capability than ceria and partial molar enthalpy and entropy that were in between those of Zr-doped ceria and undoped ceria. In the case of CO2 splitting kinetics, Zr-doped ceria was the slowest in accordance with relevant literature, but La-doped samples were much faster than Yb-doped counterparts suggesting that extrinsic oxygen vacancy formation, even though important, does not primarily determine the CO2 splitting kinetics unlike the hypothesis postulated by previous works. This work elucidates the role of dopant's ionic radius, lattice constant and valence on thermodynamics and CO2 splitting kinetics via experimental demonstration, and provides a new doping strategy not based on the extrinsic oxygen vacancy formation but based on the dopant ionic radius and valence with an insight for the further doped ceria-based redox material discovery.

Redox-Copolymers for Nanofiltration-Enabled Electrodialysis

Robust, energy-efficient separation technologies for desalination and the removal of organic contaminants are critical in addressing growing concerns about water shortage and water pollution. Here, we propose a generalized strategy for advancing electrodialysis technologies using redox-flow concepts, by implementing a water-soluble redox-copolymer, poly(ferrocenylpropylmethacrylamide-co-[2-(methacryloyloxy)ethyl]trimethylammonium chloride), P(FPMAm-co-METAC), to eliminate the need for anion-exchange membranes (AEMs) and deploy cheaper and more robust nanofiltration membranes (NFs). The effective membrane retention of the redox material and stable redox activity facilitate the continuous desalination of various source waters, including brackish water, seawater, and wastewater, to produce potable water and remove organic contaminants without membrane fouling or polymer crossover. Leveraging the reversible redox reaction of ferrocene reduces energy consumption by 88% within a single-unit cell compared to conventional ED. In addition, utilizing reusable redox-copolymer and cost-effective NFs promotes economic feasibility, achieving a water production cost of $0.13 m–3. Overall, the combination of redox-copolymer in flow and NFs provides a new avenue to address water contamination caused by organic pollutants and water scarcity in an energy efficient manner.

Voltammetric Evidence of Proton Transport through the Sidewalls of Single-Walled Carbon Nanotubes.

Understanding ion transport in solid materials is crucial in the design of electrochemical devices. Of particular interest in recent years is the study of ion transport across 2-dimensional, atomically thin crystals. In this contribution, we describe the use of a host-guest hybrid redox material based on polyoxometalates (POMs) encapsulated within the internal cavities of single-walled carbon nanotubes (SWNTs) as a model system for exploring ion transport across atomically thin structures. The nanotube sidewall creates a barrier between the redox-active molecules and bulk electrolytes, which can be probed by addressing the redox states of the POMs electrochemically. The electrochemical properties of the {POM}@SWNT system are strongly linked to the nature of the cation in the supporting electrolyte. While acidic electrolytes facilitate rapid, exhaustive, reversible electron transfer and stability during redox cycling, alkaline-salt electrolytes significantly limit redox switching of the encapsulated species. By "plugging" the {POM}@SWNT material with C60-fullerenes, we demonstrate that the primary mode of charge balancing is proton transport through the graphenic lattice of the SWNT sidewalls. Kinetic analysis reveals little kinetic isotope effect on the standard heterogeneous electron transfer rate constant, suggesting that ion transport through the sidewalls is not rate-limiting in our system. The unique capacity of protons and deuterons to travel through graphenic layers unlocks the redox chemistry of nanoconfined redox materials, with significant implications for the use of carbon-coated materials in applications ranging from electrocatalysis to energy storage and beyond.

Impact of lattice properties on the CO2 splitting kinetics of lanthanide-doped cerium oxides for chemical looping syngas production

Cerium oxide (CeO2) is the state-of-the-art material for syngas production from CO2 and H2O splitting via (methane assisted-) solar-driven thermochemical cycles. This technology consists of two separate processes: (1) a partial reduction of the oxide with methane at ∼900 °C that produces syngas and generates oxygen vacancies in the oxide lattice; and (2) oxidation of the reduced oxide by reaction with H2O and/or CO2 to form H2 and/or CO, respectively, which incorporates oxygen into the oxygen vacancy lattice sites. Doping the cerium oxide with other cations enables to increase the oxygen-vacancy concentration or to induce changes in the crystal lattice, aiming at increasing the fuel yield and/or boosting the redox oxygen-exchange kinetics. Traditionally, CeO2 has been doped with lanthanides to improve the redox behavior and enhance ionic conduction. For lanthanide-doped cerium oxides, a correlation between the dopant's ionic radius and the material's ionic conductivity has been established. Here, we examine the impact of the trivalent lanthanide dopants on the methane partial oxidation and CO2 splitting. Our results reveal a correlation between the dopant ionic radius, ionic conductivity, oxygen exchange kinetics, and CO2 splitting kinetics. We could identify the optimum ionic radius for enhanced CO2 splitting kinetics based on our observations. These findings are an essential framework for designing more advanced redox materials for chemical looping syngas production.

NiZrSe3/rGO modulated porous architecture for hybrid featured asymmetric supercapacitors

Designing transition metallic chalcogenides with rGO as a potential porous platform for growth are vital to upsurge the electrochemical energy storage capabilities of supercapacitors' electrodes. This work reports hydrothermally prepared agglomerated NiZrSe3 nanoparticles and a porous NiZrSe3/rGO, where the latter exhibits superior charge storage properties. In comparison to NiZrSe3 with specific capacitance (Cs) of 1415.7 F/g, the porous modulated material NiZrSe3/rGO delivers an exceptional Cs of 2750.8 F/g at current density of 2 A/g in the 3-electrode setup. Due to its the outstanding electrochemical performance, NiZrSe3/rGO is employed as a redox featured electrode material, and further integrated with activated carbon (ActC) as a capacitive featured electrode material to construct a hybrid asymmetric supercapacitor with widened potential window and enhanced energy density. The constructed asymmetric supercapacitor unveils a specific capacitance of 140.77 F/g at current density of 1.2 A/g and rate capability of 53.6 % at 7 A/g while functioning stably under the potential range of 0–1.65 V. Moreover, it achieves extremely high energy density of 53.22 Wh/kg at power density of 990 W/kg with its long-life span in regard to cyclic stability of 80.31 % after 10,000 charging-discharging cycles. In general, this work illustrates the significance of NiZrSe3/rGO as a highly redox active cathode material in hybrid featured asymmetric supercapacitors for future renewable energy storage systems.