Supercapacitors are a class of portable and sustainable energy storage devices with higher power and lower energy densities. Their commercial utility requires aqueous electrolytes, which hinder their flexibility, and hence, these devices may not find applications in wearable electronic devices. The evolution of polymers and solidstate electrolytes could solve flexibility issues with supercapacitors. The utility of different solid state and polymer electrolytes raises critical questions about stability, electrical conductivity, practical cyclability, and operational temperatures of the flexible devices. This Review discusses broad categories of solid-state electrolytes such as inorganic solid electrolytes, gel polymer electrolytes, and polyelectrolytes. The fabricated flexible solid-state supercapacitors’ electrochemical characterization and sustainable charge storage routines are discussed.

Carbon derived from biomass, characterized by its abundant porosity and adaptable physical and chemical traits, has emerged as a promising choice for electrode materials in electrochemical energy storage devices like supercapacitors and lithium–sulfur (Li–S) batteries, marking a rapidly advancing field. Herein, we report the creation of a fresh biomass-derived activated carbon produced via a pyrolysis technique using a blend of indigenous European deciduous trees, including Birch, Fagaceae, and Carpinus betulus (commonly referred to as European hornbeam). The biomass-derived activated carbon underwent various material characterizations to scrutinize its structural, morphological, and elemental compositions. Utilizing this biomass-derived activated carbon as the electrode material across different supercapacitor configurations (such as coin cells and printable miniaturized devices) and as sulfur hosts in Li–S batteries paves the way for expanded applications in biomass energy utilization. The supercapacitor devices were successfully fabricated and shown to be operated efficiently within an operational potential range of 2.5 V (0.0–2.5 V) utilizing an EMIMBF4 ionic liquid electrolyte. The symmetrical coin cell supercapacitor device achieved a notable energy density of approximately 23.52 W h kg−1 when subjected to an applied current density of 0.66 A g−1. Furthermore, Li–S batteries were assembled, incorporating a composite cathode composed of activated carbon derived from biomass and sulfur. Subsequently, cyclic voltammetry alongside charge–discharge assessments at varying scan rates and C-rates were performed, respectively. The sulfur–biomass-derived activated carbon (BAC) composite delivers an initial discharge capacity of 661 mA h g−1 at a C-rate of 0.05C. Long-term cycling tests were conducted at 1C and 0.5C over 500 cycles, achieving coulombic efficiencies of approximately 99% and 97%, respectively, in sulfur–biomass-derived activated carbon composite-based Li–S batteries. Hence, our research showcases the scalable synthesis of biomass-derived activated carbon and its utilization as a versatile electrode material, laying the groundwork for the next generation of multifunctional sustainable energy storage systems.

With the rapid advancement of portable electronic devices, the demand for miniaturized and integrated energy-storage systems has grown significantly. Among these, microbatteries and microsupercapacitors (MSCs) play a crucial role in powering nextgeneration wearable and flexible electronics. In this study, we report high-performance MSCs based on various polymorphs of vanadium dioxide (VO2), including VO2(A), VO2(B), VO2(D), and VO2(M) on laser-induced graphene (LIG) polyimide (PI) films. Through comprehensive electrochemical characterization, we found that the flexible VO2(M)-based MSC exhibited a superior energy-storage performance, delivering a high specific energy of 0.66 mWh cm−2 and a power density of 858 W cm−2, outperforming other VO2 polymorphs. Furthermore, the device demonstrated remarkable mechanical flexibility, maintaining a stable electrochemical performance even at bending angles of 0°, 120°, and 180°. These findings highlight the potential of VO2(M)-based MSCs as promising candidates for all-solid-state, flexible, miniaturized energy-storage devices, paving the way for their integration into next-generation portable and wearable electronic devices.

We report the electrochemical charge storage performance of NiSb2O6, obtained through a solid-state reaction method, and a detailed comparison with its reduced graphene oxide composite. Intriguingly, the composite, NiSb2O6–reduced graphene oxide, yielded a large capacitance of 952.38 F g−1, at a mass-normalized-current of 1 A g−1, which is at least 4-fold higher than that of the bare NiSb2O6. We have also tested the performance of the composite in a two-electrode symmetric device. The NiSb2O6–reduced graphene oxide symmetric device showed an excellent capacity retention of ∼94%, even after 10[thin space (1/6-em)]000 cycles. We conducted comprehensive density functional theory (DFT) simulations to determine the structure and electronic characteristics of NiSb2O6, and the composite material of NiSb2O6–reduced graphene oxide. The incorporation of reduced graphene oxide results in an augmentation of electronic states near the Fermi level, hence showing an improvement in the conductivity of the hybrid system. The composite structure exhibits a lower diffusion energy barrier for electrolyte ions and a greater quantum capacitance than pristine NiSb2O6. These characteristics confirm our experimental findings and justify the observed improvement in charge storage performance for the composite structure. Based on the results obtained, it can be concluded that the combination of rGO and NiSb2O6 displays excellent performance and has the potential to serve as a highly efficient material for electrochemical capacitors.

Two-dimensional (2D) piezoelectric hexagonal boron nitride nanoflakes (h-BN NFs) exhibit substantial potential for energy harvesting, electronics, and optoelectronics applications. Herein, a free-standing PVDF/h-BN NFs (Ph-BN) composite film is synthesized for multi-functional purposes. First and foremost, a piezoelectric nanogenerator (PENG) device is fabricated using free-standing Ph-BN composite films and the energy harvesting properties are performed. The nanogenerator, Ph-BN-7.5 PENG, exhibits the highest output voltage of 50 V and current of 250 nA with a maximum power of about 2 μW compared to other fabricated composite devices. Further, a photo power cell (PPC) is fabricated using PVA-EY mixture dye as the photosensitive part or solar energy absorber, and Ph-BN 7.5 film is utilized as the energy storage part. The PPC is self-charged up to ≈1 V within 80 s under light illumination. The self-charging mechanism for PPC is explained in detail. The Ph-BN composite films demonstrate an innovative energy harvesting and storage approach, which can fulfill the energy prerequisite in the imminent future.

Lithium-sulfur battery (LSB) chemistry is regarded as one of the most promising contenders for powering next-generation electronics, including electric vehicles. This is due to its high theoretical capacity, the use of inexpensive and environmentally friendly materials, and its alignment with climate-smart manufacturing principles. Sulfur, the electroactive element in LSBs, undergoes lithiation to form a series of polysulfides, each contributing to the battery's energy density. However, this chemistry encounters several challenges, particularly concerning the stability of sulfur. Recent studies have shown that the presence of a full gamma phase of sulfur in an LSB cathode significantly enhances the capacity and overall cell performance. However, despite the advantages of cathodes with gamma sulfur, the characteristics of LSBs with mixed crystal phases of sulfur (alpha, beta, and gamma) have not been extensively studied. In this context, we developed a simple and cost-effective synthesis method to produce both single-phase (alpha) and mixed-phase sulfur (primarily a mixture of alpha and gamma, with a trace of beta) and conducted their detailed physical and electrochemical characterization for use as electroactive cathode materials in LSBs. The cells fabricated using sulfur-carbon black as the cathode delivered a specific capacity of approximately 640 mAh/g at a current density of 275 mA/g, demonstrating excellent cyclic stability over 50 cycles with a capacity retention of around 97%. This performance is superior to that of the sulfur-baked carbon black composite cathode, which achieved 440 mAh/g at the same current density.

The globe is currently dealing with serious issues related to the world economy and population expansion, which has led to a significant increase in the need for energy. One of the most promising energy devices for the next generation of energy technology is the supercapacitor (SC). Among the numerous nanostructured materials examined for SC electrodes, inorganic nanosheets are considered to be the most favorable electrode materials because of their excellent electrochemical performance due to their large surface area, very low layer thickness, and tunable diverse composition. Various inorganic nanosheets (NS) such as metal oxides, metal chalcogenides, metal hydroxides, and MXenes show substantial electrochemical activity. Herein, a comprehensive survey of inorganic NS arrays synthesized through the electrodeposition method is reported with the discussion on detailed growth mechanism and their application in the fabrication of SC electrodes/devices for powering flexible and wearable electronics appliances. To begin with, the first section will feature the various types of electrodeposition working mechanism, SC types and their working mechanisms, importance of nanosheet structure for SCs. This review gives a profound interpretation of supercapacitor electrode materials and their performances in different domains. Finally, a perspective on NS array through electrodeposition method applications in diverse fields is extensively examined.

The ever-growing demand for portable, bendable, twistable, and wearable microelectronics operating in a wide temperature range has stimulated an immense interest in the development of solid-state flexible energy storage devices using scalable fabrication technology. Herein, we developed additively manufactured graphene aerosol gel-based all-solid-state micro-supercapacitors (MSCs) via inkjet printing with functioning temperature in the range from −15 to +70 °C and exhibiting a super-stable and reliable electrochemical performance using interdigitated finger electrodes and PVA/H3PO4 solid-state electrolyte. The graphene aerosol gel was obtained using a scalable single step synthesis method from a gas phase precursor using a detonation process, producing a nanoscale shell type structure. The fabricated graphene aerosol gel-based solid-state MSC achieved a volumetric capacitance of 376.63 mF cm−3 (areal capacitance of 76.23 μF cm−2) at a constant current of 0.25 μA and demonstrated exceptional cyclic stability (∼99.6% of capacitance retention) over 10 000 cycles. To exploit the mechanical strength of the as-fabricated graphene aerosol gel-based solid-state MSC, its supercapacitive performance was scrutinized under various bending and twisting angles and the results showed excellent mechanical flexibility. Furthermore, to study the electrochemical performance of the as-fabricated graphene aerosol gel solid-state MSC in stringent surroundings, a broad temperature dependent supercapacitive analysis was performed as stated above. The electrochemical results of the as-fabricated graphene aerosol gel based all-solid-state MSC exhibit a highly potential route to develop scalable and authentic future miniaturized energy storage devices for IoT based smart electronic appliances.

Commercial lithium-ion batteries generate significant carbon footprint during the procurement of relatively scarce raw materials of Li, Co, Ni etc, manufacturing of cell, and their recycling. Lithium – sulphur battery is far more environmentally friendly as it uses only scarce lithium, has significantly higher specific energy density than Li ion cells, and easier to recycle. A facile one step scalable process has been developed to increase the loading and conductivity of sulphur; retard long chain polysulphides shuttling, tackle volumetric fluctuation of active particles and inhibit the lithium anode corrosion together with its dendritic growth during discharge – charge cycles. Electrode with EA-PAA binder delivers discharge capacity ∼836 mAh/g at 0.2C which is significantly larger than electrode made with PAA binder (∼745 mAh/g). At 1C rate electrode with EA-PAA binder delivers a discharge capacity ∼418 mAh/g which is significantly larger than electrode made using PAA binder (∼257 mAh/g). Irrespective of measured current, electrode with EA-PAA binder yields superior coulombic efficiency than electrode made using PAA binder. It is argued that the developed S/C composite with rGO additive and EA-PAA binder yields polar – polar interaction between EA-PAA binder and soluble long chain polysulphides to retard their shuttling. The EA-PAA binder with polar functional groups also have stronger bonding with underlying Al current collector. The stretchable EA-PAA binder network efficiently buffer the volumetric strain during alloying and de – alloying reactions as compare to PAA electrode. For S/C composite electrode, capacity fading during repeated cycling is thought to be related to the slower transformation kinetics of long chain polysulphides to insulating short chain lithium sulphides end product.

The advancements in electrochemical capacitors have noticed a remarkable enhancement in the performance for smart electronic device applications, which has led to the invention of novel and low-cost electroactive materials. Herein, we synthesized nanostructured Al2O3 and Al2O3-reduced graphene oxide (Al2O3-rGO) hybrid through hydrothermal and post-hydrothermal calcination processes. The synthesized materials were subject to standard characterisation processes to verify their morphological and structural details. The electrochemical performances of nanostructured Al2O3 and Al2O3- rGO hybrid were evaluated through computational and experimental analyses. Due to the superior electrical conductivity of reduced graphene oxide and the synergistic effect of both EDLC and pseudocapacitive behaviour, the Al2O3- rGO hybrid shows much improved electrochemical performance (~ 15-fold) as compared to bare Al2O3. Further, a symmetric supercapacitor device (SSD) was designed using the Al2O3- rGO hybrid electrodes, and detailed electrochemical performance was evaluated. The fabricated Al2O3- rGO hybrid-based SSD showed 98.56% capacity retention when subjected to ~ 10,000 charge–discharge cycles. Both the systems (Al2O3 and its rGO hybrid) have been analysed extensively with the help of Density Functional Theory simulation technique to provide detailed structural and electronic properties. With the introduction of reduced graphene oxide, the available electronic states near the Fermi level are greatly enhanced, imparting a significant increment in the conductivity of the hybrid system. The lower diffusion energy barrier for electrolyte ions and higher quantum capacitance for the hybrid structure compared to pristine Al2O3 justify improvement in charge storage performance for the hybrid structure, supporting our experimental findings.

Vertical graphene (VG) or vertical graphene arrays have attracted the attention of researchers in recent years, as electrode materials for supercapacitor application due to its unique properties. Although significant progress has been made in growth and supercapacitor application of VG, still many recent developments not yet been reviewed. By attuning the growth of the graphene from horizontal to vertical, its electronic band structure and bandgap can be controlled which is evident from the theoretical and experimental findings. In VG electrolyte ions could smoothly transport through regions of one-dimensional structures and access the electroactive material's surface, and electrons can successfully move in the highly conductive VG to reach the current collector. Furthermore, high surface area can also accelerate other kinetic reactions and the one dimensional structure diminishes strain through volume expansion and contraction. These superiority make VG electrodes captivating in various future energy storage devices including lithium-ion batteries and supercapacitors. Herein, the importance of the structure, overview of various plasma enhanced chemical vapor deposition (PECVD) method of synthesis and the progress in bare and hybrid VG structures are reviewed. Afterward, the important strategies to enhance the energy storage performance by changing the morphology, surface engineering/functionalization and doping of VG are discussed. Furthermore, the challenges and future perspectives for achieving good structural quality with outstanding capacitance performance are listed. This review summarises the importance of vertical graphene structure, PECVD growth and mechanism of VG with recent progress and application towards efficient supercapacitor electrode material.

Self-powered systems or self-powered devices belong to one of the most pivotal research topics that specifically aim toward the growth of portable and wearable electronic industries over the last few years. A sizeable number of self-powered systems have been established, utilizing the various modes of energy conversion (solar cells, mechanical energy harvester and thermal energy harvester) and storage technologies (batteries and supercapacitors). This review provides a summarized content regarding the research and development on the various types of self-charging supercapacitor power cells (SCSPCs) that have been developed since the past few decades. The selection of novel materials, device architecture and performance metrics are influential/critical for the evolution of SCSPCs for next-generation electronics applications. Integrating both the energy conversion and storage devices into a single system brings substantial challenges regarding the understanding of the underlying working mechanisms and its subsequent application for powering portable and wearable electronics. Up to date, state-of-the-art instances of SCSPCs fabrication technologies and performance matrices have been emphasized in this review. Furthermore, the key challenges encountered during SCSPCs fabrication, their useful applications in various fields and their possible solutions are discussed for future developments on SCSPCs.

Two-dimensional (2D) dual-functional molybdenum disulfide (MoS2) quantum sheets (QSs) are attracted extensively due to their potential use in the field of energy harvesting and storage for new-generation flexible and wearable self-powered electronics. Herein, we successfully designed the photovoltaically self-charging power cell (PSCPC) and piezoelectric nanogenerator (PNG) utilizing the 2D 1 T-MoS2 QSs incorporated polyvinylidene fluoride (PVDF) film owing large dielectric properties and boost in the piezoelectric output performance. This unique MoS2 QSs-PVDF based piezoelectric nanogenerator consistently produces an output voltage of 47 Vpp and delivered a power density of 3.2 mWm􀀀 2, respectively, which is comparably higher than pristine PVDF film. The photoelectric conversion efficiency of the photovoltaic unit and charge storage properties of the prepared film was characterized via fabricating a photovoltaically self-charging power cell using PVA/H3PO4 electrolyte, TiO2/ Eosin Y dye as photon converter and MoS2 QSs embedded PVDF as a storage unit. On the illumination of visible light, the PSCPC device can self-charge up to 900 mV with a photocurrent of 25 μA internally. In addition, the PSCPC can be integrated with clothing to generate green energy from natural sunlight and ambient indoor condition to directly power up wearable smart electronics. Overall, these studies can promote the dualfunctionality of the 1 T-MoS2 QSs in the development of flexible and wearable self-powered electronic devices.

Deciphering the charge storage mechanism of conventional supercapacitors (SCs) can be a significant stride towards the development of high energy density SCs with prolonged cyclability, which can ease the energy crisis to a great extent. Although ex situ characterization techniques have helped determine the charge storage mechanism of SCs, large unexplored grey areas with unknown ensembles still exist, which cannot be neglected. Over the past decade, in situ analytical characterization tools such as in situ X-ray diffraction (XRD), in situ X-ray absorption spectroscopy (XAS), in situ X-ray photoelectron spectroscopy (XPS), in situ Raman, in situ infrared/Fourier transform infrared spectroscopy (IR/FTIR), in situ nuclear magnetic resonance (NMR), in situ atomic force microscopy (AFM), in situ scanning electron microscopy (SEM), in situ tunnelling electron microscopy (TEM), and in situ electrochemical quartz crystal microbalance (EQCM) techniques have exclusively come to the forefront to shed light on the charge storage mechanism of SCs. This review emphases the insights into the charge storage mechanism interpreted from in situ characterization techniques together with the theoretical investigation validations. Various charge storage parameters obtained from electronic structure simulations such as quantum capacitance, voltage induced by electrolyte ions, and diffusion energy barrier of electrolyte ions are detailed with pertinent examples. The amalgamation of in situ techniques and theoretical simulations can efficiently elucidate the ion dynamics and charge transfer in SC electrode systems, giving a whole new perspective. A comprehensive classification of SCs based on their mechanism, choice of electrodes and device configuration, and explanation of the charge storage mechanism based on in situ/operando techniques together with theoretical explorations can be obtained herein.

The next generation of electronics technology is purely going to be based on wearable sensing systems. Wearable electronic sensors that can operate in a continuous and sustainable manner without the need of an external power sources, are essential for portable and mobile electronic applications. In this review article, the recent progress and advantages of wearable self-powered smart chemical sensors systems for wearable electronics are presented. An overview of various modes of energy conversion and storage technologies for self-powered devices is provided. Self-powered chemical sensors (SPCS) systems with integrated energy units are then discussed, separated as solar cell-based SPCS, triboelectric nano-generators based SPCS, piezoelectric nano-generators based SPCS, energy storage device based SPCS, and thermal energy-based SPCS. Finally, the outlook on future prospects of wearable chemical sensors in self-powered sensing systems is addressed.

Supercapacitors are widely accepted as one of the energy storage devices in the realm of sustainable and renewable energy storage. Supercapacitors have emerged as a good alternative to traditional capacitors and fuel cells due to their higher energy density and power density compared to batteries and fuel cells. However, supercapacitors have some drawbacks such as low energy density and poor cycle life compared to batteries. To overcome these issues, researchers are paying much attention to the fabrication of metal oxide nanostructures and their modification by different approaches such as doping, introducing oxygen vacancies, and hybridization with nanomaterials of carbon allotropes for enhanced electrochemical properties. In this review article, we have presented the above-mentioned topics with the aid of recently reported works. Moreover, we have provided theoretical insights from density functional theory for the electrochemical behavior of the electrode materials from the published works. This review concisely presents the advancement in the supercapacitor energy storage field and the different approaches involved in the fabrication of supercapacitor electrode materials, which will be very handy to the researchers working in the field of energy storage. Further, the challenges and future perspectives of this exciting research field are discussed in detail.

Molybdenum disulfide (MoS2) is one of the promising electrochemical energy storage materials among the recently explored 2D materials beyond the extensively studied graphene sheets. However, MoS2 in the form of quantum sheets (QSs) has not yet been examined for use in energy storage devices (batteries and supercapacitors). Here, we demonstrate the superior electrochemical charge-storage properties of exfoliated MoS2 QSs (with lateral size in the range of 5 to 10 nm) for the first time. A salt-assisted ball milling process was used to prepare MoS2 QSs in gram scale that leads to size confinement in both lateral and vertical orientations. The electrochemical analysis of MoS2 QSs indicated their superior capacitive properties compared to the bulk MoS2, which originates from the combination of quantum capacitance and electrochemical capacitance. The device specific properties of MoS2 QSs were studied by constructing a flexible symmetric supercapacitor (SSC) that demonstrated a high device capacitance (162 F g
1), energy density (14.4 Wh kg
1), good rate capability, and long cycle life. The energy storage performance metrics of MoS2 QSs based SSC device were superior compared to the state-of-art MoS2 based supercapacitors. Furthermore, a solar-driven wireless charging power system comprising the fabricated MoS2 QSs-based SSC as an energy storage device is illustrated in the view of expanding its utility towards practical applications.

In this work, a novel chalcopyrite (CuFeS2) platelet like open-pored micro-flower structured electrode material was synthesized via a one-step hydrothermal method and its electrochemical performance as an electrode material for supercapacitors were investigated. First and foremost, the structural, morphological, vibrational, and chemical compositional characteristics of the as prepared CuFeS2 were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) with elemental mapping, laser Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), respectively. Subsequently, the electrochemical properties of the CuFeS2 electrode were explored using cyclic voltammetry (CV), galvanostatic charge–discharge (CD), and electrochemical impedance spectroscopy (EIS) studies in 1 M LiOH electrolyte. Cyclic voltammetry and charge–discharge analysis reveal the pseudocapacitive nature of the CuFeS2 electrode by obtaining a maximum specific capacity of about 26.46 mA h g−1 (specific capacitance of about ∼95.28 F g−1) at a scan rate of 5 mV s−1 with a cycling stability retention of 94.38% even after 2000 cycles at a discharge current rate of 5 mA. Furthermore, in view of practical application a symmetric supercapacitor device was fabricated using the CuFeS2 electrode which delivered a maximum specific capacitance of about 34.18 F g−1 at a current rate of 1 mA and a maximum energy density of about 4.74 W h kg−1 with excellent cycling stability. The acquired results confirmed that the CuFeS2 electrode could be a prospective and electrochemically active candidate for next generation supercapacitors.

The design and development of self-charging supercapacitor power cells are rapidly gaining interest due to their ability to convert and store energy in an integrated device. Here, we have demonstrated the fabrication of a self-charging supercapacitor using siloxene sheets as electrodes and siloxene-based polymeric piezofiber separator immobilized with an ionogel electrolyte. The self-charging properties of the fabricated device subjected to various levels of compressive forces showed their ability to self-charge up to a maximum of 207 mV. The mechanism of self-charging process in the fabricated device is discussed via “piezoelectrochemical effect” with the aid of piezoelectrochemical spectroscopy measurements. These studies revealed the direct evidence of the piezoelectrochemical phenomenon involved in the energy conversion and storage process in the fabricated device. This study can provide insight towards understanding the energy conversion process in self-charging supercapacitors, which is of significance considering the state of the art of piezoelectric driven self-charging supercapacitors.

This work describes the carbothermal preparation of silicon-oxy-carbide (SiOC) lamellae using two-dimensional siloxene sheets and alginic acid as precursors. X-ray photoelectron spectra, X-ray diffraction, Fourier-transform infrared spectra, high-resolution transmission electron micrographs, and Raman spectra revealed the formation of lamella-like SiOC nanostructures. Symmetric supercapacitors (SSCs) were fabricated using SiOC nanostructures as electrodes and evaluated in aqueous (1 M Li2SO4) and organic (1 M TEABF4) electrolytes. SiOC SSC fabricated with Li2SO4 electrolyte operated over a voltage window of 2.0 V, with an energy density of 14.2 Wh kg−1 and a power density of 6666 W kg−1. SiOC SSC fabricated using TEABF4 electrolyte operates over a voltage window of 3.0 V and delivered a device capacitance of about 16.71 F g−1, energy density of 20.89 Wh kg−1, with excellent cyclic stability and superior rate capability. Strikingly, the high-power density of the TEABF4-based SiOC SSC (15,000 W kg−1) reached the required power target for next-generation electric vehicles and is suitable for high-performance supercapacitor devices.

An essential way to enhance the energy density of a supercapacitor(SC) is to use high capacitance electrode materials via developing binder-free electrode with porous and hierarchical nanostructures. Herein, we demonstrated the use of copper antimony sulfide (Cu3SbS4) nanowires directly grown on Ni foam (using a microwave- irradiation process) as a binder-free positive electrode for SCs. The growth mechanism, effect of microwave irradiation time on the morphology and electrochemical properties of Cu3SbS4 on Ni foam were discussed in detail. The cyclic voltammetric studies (using three-electrode test) of Cu3SbS4/Ni-5 electrode showed the presence of Type-C battery-like charge-storage properties. The Cu3SbS4/Ni-5 electrode delivered a high specific capacity (835.24 mA h g−1) as obtained from the charge-discharge analysis (at a current density of 2.5 mA cm−2). Further, the device specific properties of the Cu3SbS4/Ni-5 positive electrode was examined via fabricating asymmetric supercapacitors (ASCs) using two different negative electrodes viz. (i) planar-graphene, and (ii) binder-free copper molybdenum sulfide anchored on Ni foam (Cu2MoS4/Ni) electrodes, respectively. The electrochemical analyses of the fabricated ASCs revealed that the Cu3SbS4/Ni-5║Cu2MoS4/Ni ASC possess almost 3.0-fold higher energy density compared to the Cu3SbS4/Ni-5║graphene ASC. The Cu3SbS4/Ni- 5║Cu2MoS4/Ni ASC delivered a high specific device capacitance of 213.6 F g−1 with a remarkable energy density (58.15 Wh kg−1), maximum power density (6363.63Wkg−1), and better cycle-life. The use of two different binder-free electrodes in the Cu3SbS4/Ni-5║Cu2MoS4/Ni ASC results in their superior performance metrics over the reported ASCs, thus, highlighting their potential applications towards next-generation supercapacitors.

Two-dimensional transition metal chalcogenides have gained much consideration as electrode materials in electrochemical energy storage devices. In this work, we successfully prepared 2H-MoSe2 sheets and investigated their charge-storage performance in organic electrolyte via fabrication of symmetric supercapacitor (SSC). The formation of 2H-MoSe2 nanosheets was confirmed using X-ray diffraction, Xray photoelectron spectroscopy, high-resolution transmission electron microscope, Raman spectrum and mapping analyses, respectively. The cyclic voltammetric analysis revealed the presence of pseudocapacitive nature of charge-storage in the MoSe2 SSC with a specific cell capacitance of 25.31 F g
1 obtained at a scan rate of 5 mV s
1. The charge-discharge analysis revealed that the MoSe2 SSC possesses a high specific cell capacitance of 16.25 F g
1 (obtained at a current density of 0.75 A g
1), an energy density of 20.31Wh kg
1 and excellent cyclic stability with capacitance retention of about 87% over 10,000 cycles. The MoSe2 SSC delivered an excellent power density of 7.5 kWkg
1 obtained from the CD profiles measured using a current density of 5 A g
1. The energy/power density of the MoSe2 SSC device is comparable or even higher with the reported SSCs using 2D materials such as graphene sheets, siloxene sheets, and MXene sheets, respectively. Electrochemical impedance spectroscopic analysis (Nyquist and Bode plots) were used to understand the capacitive nature and charge-transfer kinetics of the MoSe2 SSC in organic electrolyte. Furthermore, we have also demonstrated the real-time application of the MoSe2 SSC as an indication of their candidature towards the development of next-generation energy storage devices.

Two-dimensional siloxene sheets are an emerging class of materials with an eclectic range of potential applications including electrochemical energy conversion and storage sectors. Here, we demonstrated the dehydrogenation/ dehydroxylation of siloxene sheets by thermal annealing at high temperature (HT) and investigated their supercapacitive performances using ionic liquid electrolyte. The X-ray diffraction analysis, spectroscopic (Fourier transform infrared, laser Raman, and X-ray photoelectron spectroscopy) studies, and morphological analysis of HT-siloxene revealed the removal of functional groups at the edges/basal planes of siloxene, and preservation of oxygen-interconnected Si6 rings with sheet-like structures. The HT-siloxene symmetric supercapacitor (SSC) operates over a wide potential window (0−3.0 V), delivers a high specific capacitance (3.45 mF cm−2), high energy density of about 15.53 mJ cm−2 (almost 2-fold higher than that of the as-prepared siloxene SSC), and low equivalent series resistance (compared to reported silicon-based SSCs) with excellent rate capability and long cycle life over 10 000 cycles.

The development of functional materials towards mechanical energy harvesting applications is rapidly increasing during this decade. In this study, we are reporting the mechanical energy harvesting properties of freestanding carbyne-enriched carbon film (prepared via dehydrohalogenation of PVDF). Physico-chemical characterizations such as X-ray diffraction, Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, 13C NMR spectroscopy, and laser Raman spectral analyses confirmed the formation of the carbyneenriched carbon film. The Raman mapping analysis revealed the homogeneous distribution of cumulenic (β- carbyne) networks in carbonoid matrix of the prepared film. The mechanical energy harvesting properties of carbyne-enriched carbon film have been examined under various applied compressive forces. The carbyne-enriched carbon film based energy harvester generates a peak to peak voltage of 6.48 V using a periodic force of 0.2 N, and the output voltage is directly proportional to the levels of applied compressive force. The carbyneenriched carbon film based energy harvester possesses an instantaneous power density of about 72 nW cm−2 with excellent electromechanical stability. These experimental findings ensure the use of carbyne-enriched carbon film as a mechanical energy harvester for the first time, which can create new insights towards the development of carbon-based mechanical energy harvesters.

A novel hybrid of Cu2MoS4 nanoparticles embedded on reduced graphene oxide (rGO) sheets was prepared via a one-pot hydrothermal method without any surfactants or templates. The electrochemical properties of the as-prepared Cu2MoS4–rGO electrode were investigated as an advanced electrode for supercapacitor applications, and it exhibited higher specific capacitance (231.51 F g−1 at 5 mV s−1) compared to the pristine Cu2MoS4 electrode (135.78 F g−1 at 5 mV s−1). The Cu2MoS4–rGO electrode showed energy density of 31.92 Wh kg−1 at a constant current of 1.5 mA, which was higher than that of the pristine Cu2MoS4 electrode (17.91 Wh kg−1 at a constant current of 1.5 mA). The satisfactory enhancement in the electrochemical performance of Cu2MoS4–rGO electrodes could be attributed to the chemical interaction between rGO sheets and Cu2MoS4 nanoparticles, which produced more active sites for the charging/ discharging process and enabled fast electron transport through the graphene layers. Furthermore, this work presented an extensive study about the effect of temperature (from 25 °C to 80 °C) on the Cu2MoS4–rGO electrode in an aqueous Na2SO4 electrolyte. The effect of temperature on the electrochemical properties of the Cu2MoS4–rGO electrode was investigated using cyclic voltammetry (CV), charge–discharge (CD) tests and electrochemical impedance spectroscopy (EIS). The electrochemical performance of the Cu2MoS4–rGO electrode exhibited ∼128% improvement at 80 °C compared to that at 25 °C in CD profiles. These experimental results indicate a fundamental comprehension of the temperature- dependent supercapacitor electrodes for industrial, military and space applications.

Transition binary metal sulfides have fascinated much attention as electrode materials for energy storage applications. Herein, we report the use of binder-free copper tungsten sulfide (CWS) anchored on Ni foam and investigated its electrochemical properties as a negative electrode for supercapacitor application. The mechanism of CWS growth on the surface of Ni foam via hydrothermal process is explained based on recrystallization of metastable precursors (RMP) process and confirmed using laser Raman spectroscopic analysis. The electrochemical analysis using three-electrode configuration reveals that the charge-storage mechanism is due to the Type-B pseudocapacitance (due to intercalation with partial redox) nature of the CWS/Ni electrode with a high specific capacitance (areal capacitance/specific capacity) of 2666.6 F g−1 (888.8 mAh g−1/ 1866.6 mF cm−2) at a constant current of 10 mA. To emphasize the potential use of CWS/Ni electrode in energy storage sector, we fabricated an asymmetric supercapacitor device using CWS/Ni (negative electrode) and graphene (positive electrode) which delivers a device specific capacitance (107.93 F g−1/226.67 mF cm−2) with a high energy density (48.57 Wh kg−1/102 μWh cm−2), and excellent electrochemical stability for 10,000 charge-discharge cycles. These results confirm that the CWS/Ni electrode can act as an effective energy-storage electrode material for high performance supercapacitors.

Carbon- and carbon derivatives are widely employed as efficient electrode materials for supercapacitor applications. Herein, we demonstrate a cost-effective dip-coating process followed by dehydrohalogenation of PVDF-Ni for the preparation of carbyne enriched carbon anchored on nickel (CEC-Ni) as high-performance electrode material. The removal of halogens in the prepared CEC-Ni were widely characterized using XRD, XPS, Laser Raman, and FT-IR analysis. The occurrence of carbon-carbon vibration in the prepared CEC-Ni foam was confirmed using FT-IR spectroscopy. Laser Raman analysis confirms that the CEC-Ni foam contains both sp and sp2 hybridized carbon. The electrochemical properties of prepared carbyne enriched carbon anchored on nickel foam electrode (CEC-NiE) showed an ideal capacitive properties and delivered a maximum specific capacitance of about 106.12 F g
1 with excellent cyclic retention. Furthermore, the mechanism of charge-storage in the CEC-NiE was analyzed using Dunn’s method. In additon, the asymmetric supercapacitor device was fabricated using CEC-NiE as positive and rGO as negative electrode achieved a remarkable energy density of 33.57 Wh Kg
1 with a maximal power density of 14825.71WKg
1. These results suggested that the facile preparation of CEC-NiE could be a promising and effective electrode material for future energy storage application.

Two-dimensional siloxene sheets are an emerging class of materials with an eclectic range of potential applications including electrochemical energy conversion and storage sectors. Here, we demonstrated the dehydrogenation/ dehydroxylation of siloxene sheets by thermal annealing at high temperature (HT) and investigated their supercapacitive performances using ionic liquid electrolyte. The X-ray diffraction analysis, spectroscopic (Fourier transform infrared, laser Raman, and X-ray photoelectron spectroscopy) studies, and morphological analysis of HT-siloxene revealed the removal of functional groups at the edges/basal planes of siloxene, and preservation of oxygen-interconnected Si6 rings with sheet-like structures. The HT-siloxene symmetric supercapacitor (SSC) operates over a wide potential window (0−3.0 V), delivers a high specific capacitance (3.45 mF cm−2), high energy density of about 15.53 mJ cm−2 (almost 2-fold higher than that of the as-prepared siloxene SSC), and low equivalent series resistance (compared to reported silicon-based SSCs) with excellent rate capability and long cycle life over 10 000 cycles.

Molybdenum sulfide materials receive high attention as high-performance electrodes for electrochemical energy storage devices. In this study, we investigate the electrochemical energy storage properties of amorphous MoS3 and crystalline MoS2 materials (prepared via thermal decomposition of ammonium tetrathiomolybdate) using an organic liquid electrolyte. Physicochemical characterization using X-ray diffraction pattern and laser Raman analysis confirms the formation of amorphous MoS3 and crystalline MoS2, respectively. The energy storage properties of MoS3 and MoS2 based symmetric supercapacitor devices were comparatively studied using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge analysis. The cyclic voltammetry analysis reveals the mechanism of charge storage in MoS3 and MoS2 is due to the ion-intercalation/de-intercalation pseudocapacitance. Electrochemical impedance spectroscopy studies reveal the better capacitance and charge-transfer nature of the crystalline MoS2 symmetric supercapacitor compared to that of the amorphous MoS3 symmetric supercapacitor. The charge–discharge analysis suggests that the MoS2 symmetric supercapacitor device possesses better electrochemical energy storage properties with a high specific capacity of 20.81mA h g−1 (24.98 F g−1) and energy density of about 20.69 W h kg−1 with the excellent cyclic stability of about 2000 cycles. The experimental results suggest that the crystalline MoS2 sheets might be a better choice than amorphous MoS3 as an electrode material for supercapacitors using an organic liquid electrolyte.

Research on the development of all-in-one self-charging supercapacitor power cells (SCSPCs) has received increasing attention during recent years. Herein, we reported a novel SCSPC device comprising twodimensional graphene sheets as electrodes for energy storage and a porous PVDF incorporated TEABF4 electrolyte as a solid-like piezo-polymer separator. Initially, the energy harvesting properties of porous PVDF films and the energy storage performance of the graphene based SCSPC device were evaluated separately. The porous PVDF film generated a voltage from 4 to 11 V when subjected to compressive forces of 5–20 N, respectively. The graphene SCSPC device delivered a highest specific device capacitance of 28.46 F g
1 (31.63 mF cm
2) with a specific energy of 35.58 Wh kg
1 and high-power density of 7500 W kg
1, respectively. Further, evaluation of the self-charging properties of the graphene SCSPC was performed by subjecting the SCSPC device to various applied compressive forces. Strikingly, the graphene SCSPC device can be charged up to 112 mV under a compressive force of 20 N within 250 seconds and the mechanism of self-charging via the piezo-electrochemical energy conversion process is discussed in detail. The experimental findings on the graphene SCSPC device can provide new insights towards the development of next-generation all-in-one energy conversion and storage devices.

Layered ternary metal chalcogenides and their hybrids are receiving fabulous attention as electrode materials for supercapacitors. Herein, we report a facile one-step hydrothermal preparation of layered famatinite/graphene hybrid-sheets and explored its electrochemical properties as a negative electrode for supercapacitors. The mechanism of formation of 2D/2D hybrid heterostructures comprising famatinite and graphene sheets is discussed using physico-chemical characterization such as X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopic analyses respectively. The famatinite/graphene hybrid-sheet electrode demonstrates high specific capacitance of about 527.76 F g􀀀 1 (specific capacity of 205.24 mAh g􀀀 1) which is 5- and 3- fold higher compared to the bare famatinite and graphene electrodes. This astonishing performance of famatinite/graphene hybrid electrode is due to the enhancement of electrolyte ion insertion/extraction kinetics compared to that of bare famatinite and graphene electrodes, as evidenced using Dunn’s method. Further, the famatinite/graphene symmetric supercapacitor exhibits an excellent energy density of about 13.45 Wh kg􀀀 1 with the maximal power density of 1250 W kg􀀀 1. Additionally, famatinite/graphene symmetric supercapacitor displays high cyclic stability of 95.5% with marvellous rate capability, indicating great promise towards the commercialization of energy storage device.

Transition metal chalcogenides become emerging materials as electrodes for electrochemical energy storage devices. In this study, we are reporting the preparation of a-MnSe nanoparticles using a one-pot hydrothermal method and examined its use as an electrode material for supercapacitors. Physicochemical characterizations such as X-ray diffraction, laser Raman, and field emission scanning electron microscopic analyses revealed the formation of a-MnSe nanoparticles. The electrochemical analysis such as cyclic voltammetry and electrochemical impedance spectroscopy suggested the mechanism of chargestorage is due to the pseudocapacitive nature of a-MnSe electrode. The a-MnSe electrode delivered a specific capacitance of 96.76 F g
1 from galvanostatic charge-discharge obtained at a constant current density of 0.1mA cm
2 with a corresponding energy density of 8.60Wh kg
1 and better cyclic stability over 2000 cycles. Further, the electrochemical performance of the a-MnSe symmetric supercapacitor device shows that the specific capacitance is about 23.44 F g
1 at a current density of 0.1mA cm
2, with a potential window of 0.8 V. The superior electrochemical performance of a-MnSe highlights the potential use as electrode material in energy storage sector.

In this study, we demonstrated the usefulness of proton conducting electrolytes (such as ammonium thiocyanate (NH4SCN) and ammonium nitrate (NH4NO3)) for electrochemical energy storage devices using activated carbon (AC) as the electrode material. The cyclic voltammetry analysis revealed the presence of rectangular shaped cyclic voltammograms indicating the presence of electrical double layer capacitance in AC electrode using NH4SCN and NH4NO3 electrolytes. The mechanism of charge-storage in AC electrode using the proton conducting electrolytes has been studied in detail using electrochemical impedance spectroscopy (Nyquist and Bode plots). The galvanostatic charge-discharge analysis revealed that a maximum specific capacitance of AC electrode using NH4SCN and NH4NO3 electrolytes was found to be 136.75 mF cm
2 and 113.38 mF cm
2 at a current density of 0.5 mA cm
2. This study would open a new avenue for the use of ammonium based proton conducting electrolytes for supercapacitor applications.

Two-dimensional nanostructured metal chalcogenides have significant consideration as electrode materials for energy storage application owing to their fascinating properties. In this work, we have grown two-dimensional MoSe2 sheets directly on the surface of nickel foam via facile one-step electrochemical deposition method and examined their use as a binder-free electrode for supercapacitor. The physicochemical characterizations such as X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectrum, and Raman analysis confirmed the formation of MoSe2 sheets on Ni foam. The effect of deposition time (5 and 10 min) on the electrochemical properties of the MoSe2 sheets are examined in detail using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopic analyses, respectively. The cyclic voltammetry profiles confirmed that the charge-storage mechanism in MoSe2 sheets is due to the ion intercalation/de-intercalation kinetics. A high specific capacity of 548mAh g
1 was obtained for the MoSe2/Ni electrode from CV profile measured using a scan rate of 5mV s
1. The MoSe2/Ni electrode delivered a specific capacity of 325.92 mAh g
1 from charge-discharge analysis obtained at constant discharge current density of 4mA cm
2 with good cyclic stability. The capacitive properties and the mechanism of charge-storage in the MoSe2/Ni electrode deposited at different time intervals were examined by the electrochemical impedance spectroscopy using Nyquist and Bode phase angle plot. The experimental results ensure that the MoSe2/Ni electrode might be used as the high-performance electrode for the next-generation energy storage devices.

Self-charging supercapacitor power cell (SCSPC) received much attention for harvesting and storing energy in an integrated device, which paves the way for developing maintenance free autonomous power systems for various electronic devices. In this work, a new type of SCSPC device is fabricated comprising 2D molybdenum di-selenide (MoSe2) as an energy storing electrode with polyvinylidene fluoride-co-hexafluoropropylene/ tetraethylammonium tetrafluoroborate (PVDF-co-HFP/TEABF4) ion gelled polyvinylidene fluoride/sodium niobate (PVDF/NaNbO3) as the piezopolymer electrolyte. The fabricated SCSPC delivers a specific capacitance of 18.93 mF cm−2 with a specific energy of 37.90 mJ cm−2 at a specific power density of 268.91 μW cm−2 obtained at a constant discharge current of 0.5 mA. The MoSe2 SCSPC device can be self-charged with the aid of mechanical deformation induced using the applied compressive force, thus making it harvest and store energy. The MoSe2 SCSPC device can be charged up to a maximum of 708 mV under a compressive force of 30 N in 100 s, and the mechanism of charge-storage is discussed in detail. The experimental findings of this work demonstrate the high efficiency of the fabricated MoSe2 SCSPC device, which can provide new insights for developing sustainable power sources for the next generation wearable electronic applications.

The ever-growing demand for energy storage devices necessitates the development of novel energy storage materials with high performance. In this work, copper molybdenum sulfide (Cu2MoS4) nanostructures were prepared via a one-pot hydrothermal method and examined as an advanced electrode material for supercapacitor. Physico-chemical characterizations such as X-ray diffraction, laser Raman, field emission scanning electron microscope with elemental mapping, and X-ray photoelectron spectroscopy analyses revealed the formation of I-phase Cu2MoS4. Electrochemical analysis using cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) showed the pseudocapacitive nature of charge-storage via ion intercalation/deintercalation occurring in the Cu2MoS4 electrode. The Cu2MoS4 electrode delivered a specific capacitance of 127 F g
1 obtained from the CD measured using a constant current density of 1.5 mA cm
2. Further, Cu2MoS4 symmetric supercapacitor (SSC) device delivered a specific capacitance of 28.25 F g
1 at a current density of 0.25 mA cm
2 with excellent rate capability. The device acquired high energy and power density of 3.92 Wh kg
1 and 1250 W kg
1, respectively. The Nyquist and Bode analysis further confirmed the pseudocapacitive nature of Cu2MoS4 electrodes. The experimental results indicate the potential application of Cu2MoS4 nanostructures as a novel electrode material for energy storage devices.

In this study, a facile one-pot hydrothermal route has been employed for the preparation of Cu3SbS4 nanoplates and its use as an electrode material for supercapacitors has been demonstrated. The physicochemical characterizations such as X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscope, and laser Raman spectroscopic studies revealed the formation of Cu3SbS4 with plate-like structures. The electrochemical properties of the Cu3SbS4 electrodes was studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) analyses. The CV analysis indicated the presence of a pair of redox peaks suggesting the pseudocapacitive nature of the Cu3SbS4 electrode with a high specific capacitance of 60 F g
1 (obtained at a scan rate of 5 mV s
1). The Cu3SbS4 electrode possess a specific capacitance of about 41.78 F g
1 obtained from the CD profiles recorded using an applied current of 0.25 mA. The Cu3SbS4 electrode possess a high energy of about 11.375Wh kg
1 and power density of 175Wkg
1 with excellent cyclic stability over 2500 cycles. The collective findings of this work suggested that the use of Cu3SbS4 nanoplates as an advanced electrode for supercapacitor applications.

Herein, we are demonstrating the use of a binder-free electrode based on copper–molybdenum–sulfide nanostructures grown on nickel foam (CMS/Ni) as a novel negative electrode for supercapacitors. The cyclic voltammetry and charge–discharge analyses reveal the pseudocapacitive nature of the CMS/Ni electrode with a high specific capacity of 633 mAh g−1 (∼20-fold higher than the binder-based CMS electrode) which is mainly due to their superior electronic conductivity and short ion transport pathways. Furthermore, the fabricated symmetric supercapacitor using the CMS/Ni electrode delivered a high device capacitance (265.62 F g−1), high energy density (23.61 Wh kg−1) and long cycle-life. The results ensure that the CMS/Ni binder-free electrode will be a promising negative electrode for high-performance supercapacitors.

A high-performance aqueous Li-ion hybrid capacitor (LHC) using sonochemically prepared copper hexacyanoferrate (Cu-HCF) and sodium alginate-derived graphitic carbon (GC) nanoparticles are capable of serving as positive and negative electrodes, respectively, is described in this report. The electrode materials were prepared in a cost-effective manner and characterized using X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR). High-resolution transmission electron microscopy (HRTEM) and surface area measurements revealed the formation of 30- to 60-nm Cu-HCF and 40- to 60-nm GC particles with specific surface areas of 48 and 802 m2ge1, respectively. Electrochemical studies including cyclic voltammetry (CV), galvanostatic charge-discharge (CD) analysis and electrochemical impedance spectroscopy (EIS) using a three-electrode configuration confirmed the presence of intercalative capacitance in the Cu-HCF electrode and double-layer capacitance in the GC electrode. Furthermore, the constructed Cu-HCFkGC aqueous LHC system operates over a wide voltage window (2.2 V) and delivers a high capacitance (63.64 F g1) and high energy density (42.78 Wh kg1) with a good rate capability. These key features make the LHC system an ideal candidate for next-generation electrochemical energy storage devices.

Sodium-ion capacitors have received much attention compared to lithium-based systems, owing to the improved safety and earth abundancy. Here, we assembled an aqueous sodium-ion capacitor by using nickel hexacyanoferrate and graphene as positive and negative electrodes, respectively, in 1 M Na2SO4 electrolyte. The fabricated capacitor can work in a wide potential window from 0 to 2 V, giving an energy density of 39.35 Whkg1 with better capacitance retention of about 91%, even after 2000 cycles. Besides, the cost-effective precursors as well as environmentally friendly and earth-abundant electrolytes with high safety will ensure that the fabricated sodium-ion capacitor system is suitable for next-generation energy storage applications.

Two dimensional sheets based on transition metal carbides have attracted much attention in electrochemical energy storage sectors. In this work, we demonstrated the fabrication and performance of titanium carbide based wire type supercapacitors (WSCs) towards next generation energy storage devices. The layered titanium carbide sheets were prepared via selective extraction of Al from the precursor Ti2AlC using hydrofluoric acid and are extensively characterized using X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform-infrared spectroscopy, and laser Raman spectral analyses, respectively. The X-ray photoelectron spectroscopy studies confirmed the presence of oxygen and fluorinated functional groups attached on the surface of titanium carbide. The electrochemical studies of the fabricated titanium carbide WSC devices showed ideal capacitive properties with a specific length capacitance of 3.09 mF cm
1 (gravimetric capacitance of about 4.64 F g
1), and specific energy density of about 210 nW h cm
1 (in length) or 315 mW h kg
1 (in gravimetric) with excellent cycling stability. Further, a detailed examination of the capacitive and charge-transfer behavior of titanium carbide WSCs has been investigated via electrochemical impedance analysis using Nyquist and Bode plots. Additionally, we have also demonstrated the practical application of the titanium carbide WSCs, highlighting the path for their huge potential in energy storage and management sectors.

Porous multi component Nickel Cobalt Manganese Sulfide (NCMS) nanosheets have been grown on Ni foam by cathodic electrodeposition method. The as-prepared NCMS nanosheets sample is used as an electrode material for supercapacitor application due to its large electrochemically active surface and high porosity structure. Moreover, NCMS nanosheets have good electrical and mechanical connections to the conductive Ni foam to achieve enhanced reaction kinetics with improved electrode integrity. The NCMS nanosheets exhibit an ultrahigh specific capacitance of 2717 F/g at a current density of 1 A/g with excellent cyclic stability and energy density of 94.07 Wh/kg. The electrodeposited NCMS nanosheets with extraordinary electrochemical performance enable the novel electrodes to hold great potential for high efficient energy storage systems.

We report growth of nickel cobalt sulfide (NCS) ultrathin nanosheets directly on Ni foam substrate by a facile and novel electrodeposition method. The as-prepared NCS sample is used as an electrode material for supercapacitor application due to their large electrochemically active surface area and interconnected nanosheet channels for the facilitation of ion transportation. The NCS nanosheets possess enhanced electrochemical performance in terms of fast and high reversible faradaic reactions characterized by prominent oxidation and reduction peaks. NCS nanosheets showed an ultrahigh specific capacitance of 1712 Fg
1 at a current density of 1 Ag
1 with excellent cyclic stability. The excellent supercapacitor performance of NCS nanosheets can be attributed to its rich redox reactions as well as high transport rate for both electrolyte ions and electrons.

Herein, we report a facile and low-cost electrodeposition approach for the synthesis of Copper Cobaltite (CuCo2O4) nanosheets on indium doped tin oxide (ITO) coated glass substrates. The crystal structure and morphology of the material are characterized by X-ray diffraction, energy dispersive X-ray analysis, Raman spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy. The synthesized CuCo2O4 nanosheets are composed of numerous nanoparticles and showed enhanced electrochemical activity for the glucose sensing and supercapacitor applications. The non-enzymatic glucose sensing performance of the nanosheets exhibits sensitivity of 8.25 mAmM
1 cm
2, linear range of detection of 5e110 mM and response time of 15 s towards glucose molecules. Similarly, supercapacitor fabricated using the CuCo2O4 nanosheets as the active electrode shows high specific capacitance of 100 F/ g at a current density of 1 A/g with remarkable cycling stability

In this study, we have reported a facile growth of ultrathin mesoporous manganese cobalt sulfide (MCS) nanosheet arrays on Ni-foam substrate by a facile electrodeposition approach for high performance supercapacitor applications. We have developed the extremely energy-saving and rapid synthetic methodologies for the growth of highly active binary transition metal sulfide. The nanosheet architectures have been characterized using the techniques such as XRD, FESEM, TEM, XPS and Raman spectroscopy to understand the growth mechanism. The high porosity, high surface area and good electrical conductivity of the MCS nanosheets arrays make it a promising electrode material for supercapacitor. MCS nanosheets exhibit a high specific capacitance of 2421 Fg
1 at a current density of 1 Ag
1 along with excellent cycling stability, demonstrating its potential as an efficient electrode material for next generation supercapacitors.

This study reports a facile hydrothermal synthesis of Copper tungsten oxide (CuWO4) and CuWO4-reduced graphene oxide hybrid nanoparticles and its application as an electrode for supercapacitor application. The morphology and composition has been characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and EDAX. The supercapacitive behavior has been studied from cyclic voltammetry and galvanostatic charge-discharge tests. The CuWO4-reduced graphene oxide hybrid nanoparticles show highest specific capacitance of 35.71 F/g at a current density of 0.25 A/g with excellent cycling stability.

Herein, we report a facile, low-cost and one-step electrodeposition approach for the synthesis MnCo2O4 (MCO) nanosheet arrays on indium doped tin oxide (ITO) coated glass substrates. The crystalline phase and morphology of the materials are studied by x-ray diffraction, energy dispersive x-ray analysis and field-emission scanning electron microscopy. The supercapacitor performance of the MCO nanosheets are studied in a three-electrode configuration in 2M KOH electrolyte. The as-prepared binder-free electrode shows a high specific capacitance of 290 F g−1 at 1 mV s−1 with excellent cyclic stability even after 1000 charge/discharge cycles. The obtained energy density and power density of the MCO nanosheets are 10.04 Wh kg−1 and 5.2 kW kg−1 respectively. The superior electrochemical performances are mainly attributed to its nanosheet like structure which provides a large reaction surface area, and fast ion and electron transfer rate.

Herein, we report successful synthesis method of spinel NiCo2O4 nanorods by a low-cost and facile hydrothermal route. Cyclic Voltametry (CV) and galvanostatic Charge-Discharge (CD) measurements deduce ideal supercapacitive performance (823 F/g) of spinel NiCo2O4 nanorods at a nominal current density of 0.823 A/g with excellent cyclic stability and energy density of 28.51 Wh/Kg.