High-Performance Hybrid Supercapacitor Based on Graphene-Wrapped Mesoporous T -Nb 2 O 5 Nanospheres Anode and Mesoporous Carbon-Coated Graphene Cathode

An Overview of the Emerging Technologies and Composite Materials for Supercapacitors in Energy Storage Applications

Energy storage is one of the challenges currently confronting the energy sector. However, the invention of supercapacitors has transformed the sector. This modern technology's high energy capacity, reliable supply with minimal lag time, and extended lifetime of supercapacitors have piqued the interest of scientists, and several investigations have been conducted to improve their development. However, there is room for improvement. Consequently, this review presents an up-to-date investigation of different supercapacitor technologies' components, operating techniques, potential applications, technical difficulties, benefits, and drawbacks. In addition, it thoroughly highlights the active materials used to produce supercapacitors. The significance of incorporating every component (electrode and electrolyte), their synthesis approach, and their electrochemical characteristics are outlined. The research further examines supercapacitors' potential in the next era of energy technology. Finally, concerns and new research prospects in hybrid supercapacitor-based energy applications that are envisaged to result in the development of ground-breaking devices, are highlighted.

Comprehensive Insight into the Mechanism, Material Selection and Performance Evaluation of Supercapatteries

Electrochemical energy storage devices (EESs) play a crucial role for the construction of sustainable energy storage system from the point of generation to the end user due to the intermittent nature of renewable sources. Additionally, to meet the demand for next-generation electronic applications, optimizing the energy and power densities of EESs with long cycle life is the crucial factor. Great efforts have been devoted towards the search for new materials, to augment the overall performance of the EESs. Although there are a lot of ongoing researches in this field, the performance does not meet up to the level of commercialization. A further understanding of the charge storage mechanism and development of new electrode materials are highly required. The present review explains the overview of recent progress in supercapattery devices with reference to their various aspects. The different charge storage mechanisms and the multiple factors involved in the performance of the supercapattery are described in detail. Moreover, recent advancements in this supercapattery research and its electrochemical performances are reviewed. Finally, the challenges and possible future developments in this field are summarized.

An ionic liquid-modified RGO/polyaniline composite for high-performance flexible all-solid-state supercapacitors

An IL-modified RGO/polyaniline composite was obtained by hydrothermal treatment and in situ polymerization, and used for high-performance supercapacitors.

Thin niobium and iron–graphene oxide composite metal–organic framework electrodes for high performance supercapacitors

A new composite NbOF–GO and FeOF–GO electrode material was synthesized by the screw-capped pressure tube method for a supercapacitor with specific capacitance values of 599 and 459 F g⁻¹ at current densities of 0.5 and 0.2 A g⁻¹.

Niobium-Based Oxides Toward Advanced Electrochemical Energy Storage: Recent Advances and Challenges

Niobium-based oxides including Nb₂ O₅ , TiNb_x O_2+2.5x compounds, M-Nb-O (M = Cr, Ga, Fe, Zr, Mg, etc.) family, etc., as the unique structural merit (e.g., quasi-2D network for Li-ion incorporation, open and stable Wadsley- Roth shear crystal structure), are of great interest for applications in energy storage systems such as Li/Na-ion batteries and hybrid supercapacitors. Most of these Nb-based oxides show high operating voltage (>1.0 V vs Li⁺ /Li) that can suppress the formation of solid electrolyte interface film and lithium dendrites, ensuring the safety of working batteries. Outstanding rate capability is impressive, which can be derived from their fast intercalation pseudocapacitive kinetics. However, the intrinsic poor electrical conductivity hinders their energy storage applications. Various strategies including structure optimization, surface engineering, and carbon modification are effectively used to overcome the issues. This review provides a comprehensive summary on the latest progress of Nb-based oxides for advanced electrochemical energy storage applications. Major impactful work is outlined, promising research directions, and various performance-optimizing strategies, as well as the energy storage mechanisms investigated by combining theoretical calculations and various electrochemical characterization techniques. In addition, challenges and perspectives for future research and commercial applications are also presented.

Conductive Mesoporous Niobium Nitride Microspheres/Nitrogen-Doped Graphene Hybrid with Efficient Polysulfide Anchoring and Catalytic Conversion for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are promising next-generation energy storage devices because of their high energy density of 2600 Wh kg^-1. Efficient immobilization and fast conversion of soluble lithium polysulfide intermediates (LiPSs) are crucial to the electrochemical performance of Li-S batteries. Herein, we report a novel strategy to simultaneously achieve large capacity, high rate capability, and long cycle life by utilizing mesoporous niobium nitride microspheres/N-doped graphene nanosheets (NbN@NG) hybrids as multifunctional host materials for sulfur cathodes. The mesoporous NbN microspheres chemically immobilize LiPSs via Nb-S chemical bonding and catalytically promote conversion of LiPSs into insoluble Li₂S resulting in enhanced redox reaction kinetics. Moreover, the highly conductive NbN and N-doped graphene nanosheets provide rapid electron transport and consequently, the S/NbN@NG cathode demonstrates a large capacity of 948 mAh g^-1 at 1 C (1 C = 1650 mA g^-1), high rate capability of 739 mAh g^-1 at 5 C, and excellent cycle stability with a capacity decay of 0.09% per cycle for over 400 cycles. The results described here provide insights into the design of multifunctional host materials for high-performance Li-S batteries.

Basic properties mapping of anodic oxides in the hafnium-niobium-tantalum ternary system

A thin film combinatorial library deposited by co-sputtering of Hf, Nb and Ta was employed to characterise fundamental properties of the Hf-Nb-Ta system. Compositional mappings of microstructure and crystallography revealed similarities in alloy evolution. Distinct lattice distortion was observed upon addition of hexagonal Hf, leading to amorphisation of alloys containing more than 32 at.% Hf and less than 27 and 41 at.% Nb and Ta, respectively. Volta potential and open circuit potential mappings indicated minimal values for the highest Hf concentration. Localised anodisation of the library by scanning droplet cell microscopy revealed valve metal behaviour. Oxide formation factors above 2 nm V^-1 were identified in compositional zones with high amounts of Nb and Ta. Fitting of electrochemical impedance spectroscopy data allowed electrical permittivity and resistivity of mixed oxides to be mapped. Their compositional behaviours were attributed to characteristics of the parent metal alloys and particularities of the pure oxides. Mott-Schottky analysis suggested n-type semiconductor properties for all Hf-Nb-Ta oxides studied. Donor density and flat-band potential were mapped compositionally, and their variations were found to be related mainly to the Nb amount. Synergetic effects were identified in mappings of Hf-Nb-Ta parent metals and their anodic oxides.

Electrode Materials, Electrolytes, and Challenges in Nonaqueous Lithium-Ion Capacitors

Among the various energy-storage systems, lithium-ion capacitors (LICs) are receiving intensive attention due to their high energy density, high power density, long lifetime, and good stability. As a hybrid of lithium-ion batteries and supercapacitors, LICs are composed of a battery-type electrode and a capacitor-type electrode and can potentially combine the advantages of the high energy density of batteries and the large power density of capacitors. Here, the working principle of LICs is discussed, and the recent advances in LIC electrode materials, particularly activated carbon and lithium titanate, as well as in electrolyte development are reviewed. The charge-storage mechanisms for intercalative pseudocapacitive behavior, battery behavior, and conventional pseudocapacitive behavior are classified and compared. Finally, the prospects and challenges associated with LICs are discussed. The overall aim is to provide deep insights into the LIC field for continuing research and development of second-generation energy-storage technologies.

Graphene-based ordered mesoporous carbon hybrids with large surface areas for supercapacitors

Graphene-ordered mesoporous carbon hybrids exhibited advanced specific capacity, high energy density and power density, and long cycle life.

General fabrication of mesoporous Nb2O5 nanobelts for lithium ion battery anodes

Mesoporous Nb₂O₅ NBs with good crystallinity and large specific area have been synthesized by sequential annealing of solid Nb₂O₅ NBs in NH₃ and air,exhibiting an enhanced capacity and rate capability than that of solid Nb₂O₅ NBs.