Charge Storage Research Articles

Multifunctional polymeric coating on stainless steel current collectors in aqueous energy storage devices

Herein, low cost stainless steel foils are employed as current collectors in aqueous Na-ion supercapacitors, while the foils are coated with following conducting polymers, namely, polyimide (PI), Schiff base polymer (SBP), polyanthraquinone sulfide (PAQS) and polyaniline (PANI). The foremost purpose of these polymeric coatings is the prevention of corrosion, and the resultant improvements in device performances. Notwithstanding, these polymeric coatings provide few additional benefits in device characteristics, and these are following: (i) enhancement of electrolyte stability window, (ii) contributing charge storage capacitance, (iii) conversion of 2D pristine substrate to 3D porous current collector. The four coating polymers are electrochemically characterized, and PI is selected for fabricating Na-ion supercapacitor cells. The PI-coating reduces the stainless steel’s corrosion rate ∼ 68 times, expands the electrolyte stability window ∼ 1.2 times, and delivers ∼ 2 times higher capacitance with respect to pristine current collector, whereas no appreciable interfacial resistances are observed. The supercapacitor cell with PI-functionality demonstrates ∼ 6.6 times improved capacitance than that of pristine cell at 25 mA/g current density, while > 95 and ∼ 90 % Faradaic efficiencies are noted for former and latter, respectively. The distinct enhancement of cell performances clearly demonstrates the effectiveness of multifunctional polymeric coating on corrosion-prone metallic current collectors.

Engineering Mn Vacancies to Enhance Ion Kinetics in Layered Manganese Silicate for High-Energy and Durable Intercalation Pseudocapacitance.

Transition metal silicates (TMSs) are potential electrodes for aqueous metal-ion intercalation pseudocapacitors owing to their superior theoretical capacity and high structural stability. However, the narrow interlayer spacing and intrinsic inert basal plane of TMSs lead to sluggish ions and charge transfer, causing an undesirable energy storage performance. Herein, rich Mn vacancies are introduced in layered manganous silicates (M2-xS@FA) to expedite K+ diffusion, while enhancing charge storage capacity and prolonging lifespan. In situ characterizations validate the K+ intercalation pseudocapacitance mechanism with evident crystal structure and valence state variations in M2-xS@FA. Both theoretical calculations and electrochemical experimental evaluations elucidate the imperative role of Mn vacancies in enhancing K+ diffusion kinetics and electron transfer through increased interlayer spacing and activated basal plane. Mn vacancies further boost the charge storage capacity by providing additional K+ storage sites, while simultaneously reinforcing local atomic bonding within M2-xS@FA, thereby augmenting structural stability. The assembled aqueous asymmetric solid-state cell, featuring a M2-xS@FA cathode, demonstrates exceptional power and energy densities (144.08 W h kg-1 at 375.80 W kg-1) and ultralong lifespan (100% capacity retention after 10,000 cycles). This work heralds a paradigm whereby modulating cation vacancies in layered TMSs significantly enhances K+ storage and stability for high-energy intercalation pseudocapacitance.

Enhancing Zn2+/H+ Joint Charge Storage in MnO2: Concurrently Tailoring Mn's Local Electron Density and O's p-Band Center.

Enhancing proton storage in the zinc-ion battery cathode material of MnO2 holds promise in promoting its electrochemical performance by mitigating the intense Coulombic interaction between divalent zinc ions and the host structure. However, challenges persist in addressing the structural instability caused by Jahn-Teller effects and accurately modulating H+ intercalation in MnO2. Herein, the doping of high-electronegativity Sb with fully occupied d-orbital in MnO2 is reported. The Sb doping strategy engenders the formation of Mn-O-Sb path in the structure with a strong dipole polarization field, which facilitates the delocalization of eg orbital electron in Mn and thus mitigates the Jahn-Teller effects. Simultaneously, adjusting the level of Sb doping in MnO2 leads to modulation of the p-band center of O, optimizing its interaction with hydrogen and thereby enhancing proton storage. Consequently, MnO2 doped with 6% Sb exhibits commendable performance in both rate capability and cycling endurance, delivering 113 mAh g-1 at 2 A g-1 after 2000 cycles. This investigation underscores the crucial role of electronic structural engineering in elevating the electrochemical performance of cathode materials for zinc-ion batteries.

Preinserted Ammonium in MnO2 to Enhance Charge Storage in Dimethyl Sulfoxide Based Zinc-Ion Batteries.

Nonaqueous zinc-ion batteries (NZIBs) featuring manganese dioxide (MnO2) cathodes position themselves as viable options for large-scale energy storage systems. Herein, we demonstrate the use of ammonium cation as a preintercalant to improve the performance of the δ-MnO2 cathode in wet dimethyl sulfoxide based electrolytes. Employing in situ X-ray absorption spectroscopy, Raman spectroscopy, and synchrotron X-ray diffraction, we reveal that the integration of ammonium cations promotes the formation of NH-O-Mn networks. These networks are crucial for manipulating the distortion of the MnO6 octahedral units during discharging, thereby mitigating charge disproportionation, which is a primary limitation to MnO2's charge-storage efficiency. The modified MnO2, through this idea, displays a notable improvement in capacity (∼247 mAh/g) and can pass charge-discharge cycles up to 500 cycles with a capacity retention of 85%. These findings underscore the potential of modified MnO2 in advancing MnO2-based hosts for Zn-MnO2 batteries, marking significant progress toward next-generation energy storage solutions.

Polyelectrolyte-coated zeolite-templated carbon electrodes for capacitive deionization and energy generation by salinity exchange

As global demands for freshwater and renewable energy intensify, capacitive deionization (CDI) emerges as a promising technique for water purification, desalination, and ionic separation. Reciprocally, energy harvesting has been made possible from exchanging solutions with different salinity, using the so-called capacitive mixing (CapMix) methods, now taking their first steps towards a wider range of application. In all the techniques mentioned, porous electrodes are used in order to maximize the stored charge, making it essential to properly select the material of which the electrode is composed. This work focuses on exploring the performance of zeolite-templated carbon (ZTC) as a highly promising electrode material. ZTC offers ordered pore distribution and high electrical conductivity, making it in principle ideal for energy harvesting and water purification applications. In order to optimize its performance, the surface of the ZTC is for the first time modified by application of polyelectrolyte coatings, resulting in so-called soft electrodes or SEs. This combination of electrode material and functionalization gives rise to a highly efficient and low energy-consuming strategy to fully realize the potential of this carbon material in CDI and CapMix techniques for tackling global freshwater and energy challenges. Energy and power generation values up to 25 mJ and 7.5 mW m−2 have been obtained (with measured potential rises of 131 mV by only exchanging salinities of the bathing solution), which overcome values such as 4.3 mW m−2 previously found in our laboratory under similar conditions.

S‐Tetrazine‐Bridged 2,2′‐Bipyrimidine as Superior Atom‐Economic Multi‐Charge Cathode Material for Lithium‐Ion Batteries

AbstractNitrogen‐containing heterocyclic molecules feature metal resource‐independence, flexible conjugation structure and fast charge storage kinetics, making them promising to be used as the electrode material in lithium‐ion batteries. However, an insufficiently high capacity (<400 mAh g−1) seriously threatens their practical application. Herein, a novel molecule, viz. 3,6‐bis(2‐pyrimidinyl)‐1,2,4,5‐tetrazine (DPmT), is developed by inserting an electron‐withdrawing π‐bridge unit of s‐tetrazine between two pyrimidine rings, in which a dense assembly of multiple active sites is realized. The DTmP exhibits a remarkable atom economy of 40 g (mol e)−1, which refers to the molecule mass per unit of charge transferred. The cathode material of DPmT yields a high capacity of 653 mAh g−1 and an energy density of 1188 Wh kg−1 at 50 mA g−1 at 70 °C. And 80% capacity retention is achieved after 500 cycles at 500 mA g−1, confirming its superior cyclability. Spectroscopy studies and theoretical calculations are performed to investigate the charge storage process. First, the C═N and N═N are claimed as plausible binding sites for the lithium ions. Second, the introduction of s‐tetrazine significantly enhances molecular planarity, thereby promoting charge delocalization and molecular stability. This work provides a novel strategy for designing atom‐economic multi‐charge electrode materials with high capacity.

Unveiling the Hidden Potential of Two-Dimensional Black Phosphorus for Advanced Supercapacitor Applications.

In response to the contemporary energy crisis, researchers have intensified efforts to explore green and renewable energy sources alongside developing robust energy storage devices. Supercapacitors stand out among various storage options due to their high-power density and rapid charge-discharge cycles. However, their lower energy density poses a challenge, leading to exploration of diverse electrode materials, including black phosphorus (BP). BP, with its two-dimensional (2D) layered structure akin to graphene, exhibits exceptional properties, making it a promising candidate for various applications, including energy storage. This Perspective focuses on the properties of BP as an electrode material for supercapacitors, covering electrochemical performance, charge storage mechanisms, and synthesis methods. Challenges such as restacking and stability have prompted innovative strategies to enhance BP-based supercapacitors, both qualitatively and quantitatively. Furthermore, the fabrication of BP-based hybrid nanocomposites with carbonaceous polymers, conducting polymers, and other 2D materials is discussed, highlighting their efficacy as electrode materials along with future outlooks.

Enhanced electron transfer kinetics via constructing co-catalytic system of cerium oxide and carbon dots enabling efficient electrosynthesis of hydrogen peroxide in neutral media

The sluggish kinetics coupled with the competition of four-electron pathway in neutral media diminishes the production efficiency of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e− ORR). To address this dilemma, this contribution proposes one electron modulation strategy to expedite the charge transfer capability by integrating carbon dots with CeO2 (CDs/CeO2) for the efficient neutral electrosynthesis of H2O2. It was found that the integration could effectively bolster both the activity and selectivity of 2e− ORR on CDs and CeO2. Remarkably, the highest 2e− selectivity could reach up to 92 % for the optimized CDs/CeO2, substantially surpassing that (77 %) of pristine CeO2, together with about 1.5 times enhancement of activity. Meanwhile, it also delivered a superior long durability at 20 mA cm−2 for 24 h and a high Faraday efficiency of 97 %. Further in-situ transient potential scanning (TPS) technique revealed that the pseudo-capacitance and charge storage capacity of CeO2 were significantly tuned by CDs during dynamic ORR process, being conducive to the reaction kinetics and the 2e− selectivity. The findings in this work not only extends the co-catalytic system based on CDs and rare earth materials for 2e− ORR, but also offers novel insights into correlation between their electron distribution dynamics and 2e− ORR performance.

One-Step Synthesis of Heterostructured Mo@MoO2 Nanosheets for High-Performance Supercapacitors with Long Cycling Life and High Rate Capability.

Supercapacitors have gained increased attention in recent years due to their significant role in energy storage devices; their impact largely depends on the electrode material. The diversity of energy storage mechanisms means that various electrode materials can provide unique benefits for specific applications, highlighting the growing trend towards nanocomposite electrodes. Typically, these nanocomposite electrodes combine pseudocapacitive materials with carbon-based materials to form heterogeneous structural composites, often requiring complex multi-step preparation processes. This study introduces a straightforward approach to fabricate a non-carbon-based Mo@MoO2 nanosheet composite electrode using a one-step thermal evaporating vapor deposition (TEVD) method. This novel electrode features Mo at the core and MoO2 as the shell and demonstrates exceptional electrochemical performance. Specifically, at a current density of 1 A g-1, it achieves a storage capacity of 205.1 F g-1, maintaining virtually unchanged capacity after 10,000 charge-discharge cycles at 2 A g-1. The outstanding long-cycle stability is ascribed to the vertical two-dimensional geometry, the superior conductivity, and pseudocapacitance of the Mo@MoO2 core-shell nanosheets. These attributes significantly improve the electrode's charge storage capacity, charge transfer speed, and structural integrity during the cycling process. The development of the one-step grown Mo@MoO2 nanosheets offers a promising way for the advancement of high-performance, non-carbon-based supercapacitor nanocomposite electrodes.

2D Carbonaceous Materials for Molecular Transport and Functional Interfaces: Simulations and Insights.

ConspectusCarbon-based two-dimensional (2D) functional materials exhibit potential across a wide spectrum of applications from chemical separations to catalysis and energy storage and conversion. In this Account, we focus on recent advances in the manipulation of 2D carbonaceous materials and their composites through computational design and simulations to address how the precise control over material structure at the atomic level correlates with enhanced functional properties such as gas permeation, selectivity, membrane transport, and charge storage. We highlight several key concepts in the computational design and tuning of 2D structures, such as controlled stacking, ion gating, interlayer pillaring, and heterostructure charge transfer.The process of creating and adjusting pores within graphene sheets is vital for effective molecular separation. Simulations show the power of controlling the offset distance between layers of porous graphene in precisely regulating the pore size to enhance gas separation and entropic selectivity. This strategy of controlled stacking extends beyond graphene to include covalent organic frameworks (COFs) such as covalent triazine frameworks (CTFs). Experimental assembly of the layers has been achieved through electrostatic interactions, thermal transformation, and control of side chain interactions.Graphene can interface with ionic liquids in various forms to enhance its functionality. A computational proof-of-concept showcases an ion-gating concept in which the interaction of anions with the pores in graphene allows the anions to dynamically gate the pores for selective gas transport. Realization of the concept has been achieved in both porous graphene and carbon molecular sieve membranes. Ionic liquids can also intercalate between graphene layers to form interlayer pillaring structures, opening the slit space. Grand canonical Monte Carlo simulations show that these structures can be used for efficient gas capture and separation. Experiments have demonstrated that the interlayer space can be tuned by the density of the pillars and that, when fully filled with ionic liquids and forming a confined interface structure, the graphene oxide membrane achieves much higher selectivity for gas separations. Moreover, graphene can interface with other 2D materials to form heterostructures where interfacial charge transfers take place and impact the function. Both ion transport and charge storage are influenced by both the local electric field and chemical interactions.Fullerene can be used as a building block and covalently linked together to construct a new type of 2D carbon material beyond a one-atom-thin layer that also has long-range-ordered subnanometer pores. The interstitial sites among fullerenes form funnel-shaped pores of 2.0-3.3 Å depending on the crystalline phase. The quasi-tetragonal phases are shown by molecular dynamics simulations to be efficient for H2 separation. In addition, defects such as fullerene vacancies can be introduced to create larger pores for the separation of organic solvents.In conclusion, the key to imputing functions to 2D carbonaceous materials is to create new interactions and interfaces and to go beyond a single-atom layer. First-principles and molecular simulations can further guide the discovery of new 2D carbonaceous materials and interfaces and provide atomistic insights into their functions.

Expediting Photo‐Charging of Semiconductors through a Bipolar Charge Storage Junction for Responsive Dark Photocatalysis

AbstractPhoto‐charging of semiconductors stores electrons for decoupled solar utilization, overcoming intermittent sunlight availability. However, the sluggish photo‐charging process impedes responsive charge storage. Herein, a bipolar charge storage junction is demonstrated to expedite the photo‐charging process within a renowned ionic‐CN/Co3O4 configuration, benefiting from their mismatched photo‐charging kinetics. Rapid photo‐hole storage associated with structural evolution at geometrically dependent Co sites in Co3O4 improves sluggish electron storage for ionic‐CN, while slow recovery of altered [CoO4] and [CoO6] structures delayed electron‐hole recombination. By passivating individual atomic sites, rapid hole storage is attributed to synergistic contributions of tetrahedral Co2⁺ and octahedral Co3⁺ species. The bipolar charge storage junction is photo‐charged at 0.86 A g−1, rivaling the electrical charging rate in ion batteries. With 60 s photo‐charging, the junction yields 0.27 mmol g−1 of “dark” hydrogen, the benchmark for such a short photo‐charging timeframe. This proof‐of‐concept design empowers the fast photo‐charging ability of bipolar charge storage junctions, advancing responsive photo‐charge storage for decoupled solar utilization.

Nickel-Copper Bimetallic Oxide Nanoparticles Prepared by Simple Coprecipitation Method as High Performance Electrode Materials for Asymmetric Supercapacitors.

Supercapacitors with transition bimetallic oxides as pseudocapacitive materials have been of wide concern for their excellent energy storage performance. In this work, a simple coprecipitation method was used to synthesize the precursor, followed by calcination to prepare Ni-Cu bimetallic oxide materials. The structure, morphology and properties of the materials prepared by different precipitating agents and different calcination temperatures of NCO-H2C2O4 precursor were investigated. The optimum precipitant was determined to be H2C2O4, and Ni-Cu nanoparticles with regular lamellar microstructure were obtained at the calcination temperature of 400 °C. The nanostructure and morphology provide a large active channel for the rapid diffusion of electrolyte ions, and the specific capacitance of NCO-H2C2O4-400 electrode material can reach 740.31 F/g Cs at 1 A/g. The investigation of charge storage mechanism shows that the contribution rate of capacitance and diffusion control is about 37.9% and 67.2%, respectively. The electrochemical test results of the asymmetric supercapacitors (ASC) constructed with NCO-H2C2O4-400 and activated carbon show that the specific capacitance, energy density, and power density of the capacitor are 52.66 F/g, 16.45 Wh/kg, and 759.51 W/kg, respectively. Even after 5000 charge/discharge cycles at 5 A/g, it can still keep 90.57% of its initial capacity. This work not only provides competitive electrode materials for energy storage devices but also provides a feasible strategy for producing complex transition metal oxide materials with high capacitance performance.

Advanced Porous Gold-PANI Micro-Electrodes for High-Performance On-Chip Micro-Supercapacitors.

The downsizing of microscale energy storage devices is crucial for powering modern on-chip technologies by miniaturizing electronic components. Developing high-performance microscale energy devices, such as micro-supercapacitors, is essential through processing smart electrodes for on-chip structures. In this context, we introduce porous gold (Au) interdigitated electrodes (IDEs) as current collectors for micro-supercapacitors, using polyaniline as the active material. These porous Au IDE-based symmetric micro-supercapacitors (P-SMSCs) show a remarkable enhancement in charge storage performance, with a 187% increase in areal capacitance at 2.5 mA compared to conventional flat Au IDE-based devices, despite identical active material loading times. Our P-SMSCs achieve an areal capacitance of 60 mF/cm2, a peak areal energy density of 5.44 μWh/cm2, and an areal power of 2778 μW/cm2, surpassing most reported SMSCs. This study advances high-performance SMSCs by developing highly porous microscale planar current collectors, optimizing microelectrode use, and maximizing capacity within a compact footprint.

Structural properties, dielectric relaxation, and impedance spectroscopy of NASICON type Na3+xZr2−xPrxSi2PO12${\rm Na}_{3+x} {\rm Zr}_{2-x} {\rm Pr}_{x} {\rm Si}_2 {\rm PO}_{12}$ ceramics

AbstractWe investigate the dielectric and impedance spectroscopic investigation of Pr‐doped NASICON type () samples as a function of temperature and frequency. The Rietveld refinement of X‐ray diffraction patterns confirms the monoclinic phase having C2/c space groups for all the samples. The scanning electron microscopy shows the granular‐like structure and energy dispersive X‐ray analysis confirms the desired compositions. The temperature (90–400 K) and frequency (20 Hz–2 MHz) dependence of electric permittivity are explained using Maxwell–Wagner–Sillars (MWS) polarization and space charge polarization mechanisms. The dielectric relaxation shows nearly equal activation energy for all the samples with a non‐Debye type of relaxation in the measured temperature range. The complex impedance analysis shows the presence of broad grain and grain boundary relaxation peaks. The stretched exponent analysis of electric modulus using the Kohlrausch–Williams–Watts (KWW) function further confirms the non‐Debye type of relaxation. Moreover, scaling analysis of the electric modulus shows a similar type of relaxation for all the samples. The ac conductivity data are fitted using modified power law, where the temperature dependence of exponent () confirms the correlated barrier hopping (CBH) type conduction for all the samples. Our results indicate that the Pr‐doped NASICON samples are potential candidates for charge storage devices due to their large electric permittivity.

Structural, Morphological, Optical and Dielectric Studies of RE3+ Doped CoFe2O4

Cobalt ferrite nanoparticles, both undoped and Eu³⁺-doped, with the formula CoEuxFe2-xO4 (where x = 0.00 and 0.10), were produced using the citrate gel auto-combustion technique. X-ray diffraction confirmed the successful formation of the phase and the purity of the synthesized nanoparticles. The morphological analysis was conducted using scanning electron microscopy (SEM). The optical properties of cobalt ferrite were analyzed using UV-Vis spectrometer. Dielectric properties, such as the real part of the dielectric constant and loss tangent, were evaluated using an LCR meter. Doping cobalt ferrite nanoparticles with europium resulted in a significant improvement in charge storage and transport characteristics.

Porous carbon derived from center part of the corn cob for high-performance symmetrical supercapacitors

The central part of agricultural waste biomass corn cob was used as carbon precursor and KHCO3 as activating agent, and porous carbon materials were prepared by one-step carbonization method. The effect of KHCO3 on the structure and properties of porous carbon was studied. The results show that KHCO3 has an etching effect on porous carbon, and the greater the amount of KHCO3, the stronger the etching effect. The obtained biomass porous carbon material has abundant pores, reasonable pore size distribution and high specific surface area, which is conducive to ion transfer and charge storage. In addition, the heteroatom self-doping of porous carbon can improve surface hydrophilicity and generate additional pseudocapacitance, thereby improving its electrochemical properties. Electrochemical characterization shows that the porous carbon has a specific capacitor of up to 323 F g−1. The assembled symmetric supercapacitor (SSC) has an energy density of 20 Wh kg−1 at a power density of 350 W kg−1. This low-cost, high-performance electrode material has potential applications in high-power supercapacitors.

Facile and scalable fabrication of flexible microsupercapacitor based on boron modified 2D/2D 1 T MoS2/MXene hybrids

Micro-supercapacitors (MSCs) with outstanding flexibility and electrochemical performance are critical for portable and miniaturized electronics. This study utilizes the potential utilization of Boron-modified MoS2/MXene heterostructure for fabricating highly efficient and durable microsupercapacitors. The Boron incorporation and hybrid formation significantly enhance the electrochemical performance of 1 T MoS2 and MXene (Ti3C2Tx) by activating their basal plane. The boron modified MoS2/Ti3C2Tx(B-1 T MoS2/Ti3C2Tx_) demonstrates excellent energy storage performance with a capacitance of around 420 Fg−1 in two-electrode system. Laser scribed graphene (LSG), chosen for its superior wettability, serves as the current collector facilitating the development of these MSC based on B-1 T MoS2/Ti3C2Tx. The resulting MSC demonstrates a high areal capacitance of nearly 72.31 mF/cm2 and excellent stability over 10,000 cycles. Density functional theory (DFT) simulations support these findings, indicating that hybridization with Ti3C2Tx and B substitution enhances the conductivity of the 1 T-MoS2 system. The quantum capacitance of B-substituted hybrid system surpasses that of the pristine material, validating the experimental observations of enhanced charge storage performance.

Nickel sulfide nanoparticles decorated on carbon spheres derived from Verbena officinalis for high-performance asymmetric all-solid-state flexible supercapacitors

The crafting and development of electrode materials possessing extensive energy storage capacities, alongside their adherence to environmental and economic principles, along with their outstanding capacitive behaviors, stand as pivotal elements in propelling the technological progress of supercapacitors. In this study, we utilized discarded Verbena officinalis (VOCs) as a carbon substrate and successfully synthesized porous hollow carbon spheres through an in-situ hydrothermal method, subsequently depositing NiS nanoparticles to form a shell-like structured material. The optimized VOCs/NiS-3 composite material exhibited an exceptional specific capacitance of 202.8 mAh g−1 at a current density of 1.0 A g−1; it maintained 71 % of its capacitance even at a high current density of 10 A g−1 (144.2 mAh g−1). After enduring 10,000 charge-discharge iterations, the preservation of charge storage capacity was 81.7 %, highlighting the material's outstanding performance in terms of rapid charge-discharge rates and enduring stability. Furthermore, within a PVA/KOH gel electrolyte, we fabricated an asymmetric all-solid-state supercapacitor device that delivered an energy density of 32.58 Wh k g−1 at a power density of 800 W k g−1. The device sustained a capacitance loss rate of 9.9 % and a coulombic efficiency of 96.8 % after 5000 cycles. Even after 3000 repeated bending at 120°, the capacitance retention reached 88.3 %, indicating the device's exceptional specific capacitance, flexibility and longevity. This research offers a renewable and waste-resource recycling design strategy for synthesizing outstanding-performance, flexible, all-solid-state supercapacitor electrode materials with NiS deposited on discarded biomass carbon, unveiling considerable potential for enhancing energy storage efficiency.

2D TiO2/Zn3V2O8 flake-like composites for hybrid storage device and simulation-based analysis of capacitive and diffusive contribution

Current electrochemical energy storage technology necessitates the development of a single energy system capable of meeting the high electrochemical efficiency demands of high energy density, power density, and long cyclic stability. To meet these requirements, it is highly desirable to develop new energy storage materials as well as understand the multiple charge storage mechanism in these materials. In this study, titanium dioxide‑zinc vanadate nanocomposites were synthesized as high electrochemical efficiency electrode materials. The electromechanical measurements showed an improved specific capacity of 525 Cg−1 for TiO2/Zn3V2O8 nanocomposite as compared to 400 Cg−1 for Zn3V2O8 at a current density of 1 Ag−1. The outstanding power density of 6562 WKg−1 with 66 WhKg−1 energy density was attained at 1 Ag−1. Moreover, the assembled device shows excellent performance by achieving 114.11 Whkg−1 energy density and 2600 Wkg−1 power density at 1 Ag−1. The practical viability of the device is demonstrated by fabricating the asymmetric coin cell which can operate the commercially available calculator for ~21 min. Additionally, MATLAB simulations at different voltage step potentials are performed to elucidate the charge storage mechanism which shows higher accuracy as compared with the conventional methods.

Strength in Unity: Designing of hybrid heterostructure (NiSe2/rGO/PANI) electrode towards high Performance, Flexible, asymmetric supercapacitor device for renewable energy storage

Heterostructure creation has been an effective strategy to synthesise hybrid supercapacitor electrodes by combining materials of various charge storage mechanisms, leveraging the advantages, and minimising the drawbacks of individual materials as separate entities. Herein, a hybrid supercapacitor electrode has been fabricated producing ternary NiSe2/rGO/PANI heterostructure, through simple hydrothermal followed by in-situ polymerisation techniques. Owing to the synergy between the materials, the electrode decorated on a flexible carbonaceous template exhibits a remarkable capacity of 657.36C g−1@1 A g−1 offering excellent stability over 12,000 cycles. Subsequently, a hybrid asymmetric supercapacitor (HASC) constructed using NiSe2/rGO/PANI as a positive electrode and AC as a negative electrode possesses a high energy density of 98.82 Wh kg−1 at a power density of 750.05 W kg−1 with a capacitive retention of 95.04 %. Encasing the complete device with Polydimethylsiloxane (PDMS) mould acting as an energy storage band demonstrates an unaltered device performance at various bending angles of 0° to 135°, which refers to its compatibility in flexible electronics. Further, the practical usefulness of the as-designed prototype has been exhibited by powering several devices such as; Light Emitting Diodes (LEDs) of various colours, homemade windmill, Arduino board, and LCD monitor via charging through a commercial silicon solar panel paving the way to bloom renewable energy conversion and storage.