Energy Storage Capability Research Articles

Effects of Co-doping on the microstructure and electrochemical performance of nickel vanadate (Ni3V2O8) electrode material for aqueous symmetric supercapacitor

Recently, there has been an increased focus on supercapacitors due to their reliable electrochemical energy storage capabilities. This study utilized an environmentally friendly facile hydrothermal method to prepare the nickel vanadate (NiVO) and cobalt-doped nickel vanadate (Co-doped Ni3V2O8) composite for supercapacitor applications. The prepared materials of pure and Co-doped Ni3V2O8 with different concentrations of Co (10 % and 15 %) were evaluated through three electrode assemblies. It is significant to note that although Co smoothed the surface of NiVO, most of the nickel vanadate crystals broke apart into tiny particles and increased the number of electroactive sites. Pure NiVO has a specific capacitance (Cs) of 1638.06 F/g at 5 mV/s. It has been observed that the electrochemical performance has been improved by adding Co 10 % and 15 % in NiVO. The 15 % Co-doped NiVO exhibits an outstanding Cs of 2641.99 F/g at a scan rate of 5 mV/s with a high capacitance retention of 98.14 % after 1k charge-discharges cycles. This excellent performance of the material is due to more electroactive sites and synergistic effects among Co and Ni in the composite. To further elaborate the electrochemical performance of 15 % Co-doped NiVO, it is employed for the fabrication of a symmetries supercapacitor (SSC) device, which shows that the fabricated device has a capacitance of 286 F/g at a current density (CD) of 0.5 A/g and high energy density of 39.7 Wh/kg at a power density of 333.33 W/kg. The symmetric device maintains a cyclic stability of 93.8 % while undergoing 5000 consecutive charge–discharge cycles at a current density of 10 A/g. Based on rigorous testing and analysis, these findings suggest that the prepared electrode material is reliable and suitable for implementation in forthcoming wearable electronic systems.

Collaborative Optimization for Active Distribution Network with Soft Open Point and Energy Storage

Background: The increasing use of high-penetration distributed clean energy has led to voltage fluctuations in the distribution network that surpass safety limits and pose challenges to economic and low-carbon operation. Traditional voltage regulation devices are unable to meet the real-time high-precision voltage control needs when encountering frequent fluctuations due to physical limitations. The Soft Open Point (SOP) can provide continuous reactive power to achieve rapid voltage regulation. Objective: We propose a collaborative optimization approach that fully considers the regulatory capabilities of SOP and energy storage to eliminate voltage violations and reduce network losses. Methods: This study introduces an active distribution network reactive power voltage optimization approach that incorporates intelligent SOP and energy storage, combining conventional devices (such as on-load tap changers and capacitor banks) with contemporary devices (such as SOP, distributed generators, and energy storage) to establish synergy. A coordinated optimization model was developed, considering various operational constraints to minimize network losses and regulate the voltage of distribution network nodes. By using linearization and quadratic relaxation, the original non-convex mixed-integer non-linear optimization model was transformed into a Mixed-Integer Second-Order Cone Programming (MISOCP) model to meet the requirements of rapid voltage regulation. Results: A case study was conducted on the IEEE 33-node test system, showing that the proposed approach effectively reduces network losses and eliminates voltage violations. Conclusion: The feasibility and effectiveness of the proposed methodology have been validated, confirming its ability to ensure the safe and economic operation of active distribution networks.

Attaining superior performance in an aqueous hybrid supercapacitor based on N-Doped highly porous carbon spheres and N-S dual doped Co3O4

Cobalt oxide (Co3O4) has seen a significant interest for its application as an electrode for supercapacitors, due to its cost-effectiveness, high theoretical capacitance and outstanding redox activity. However, Co3O4 exhibits poor electrical conductivity and cycle life restricting its high-power energy storage applications. High porosity carbons are materials of choice for applications in electric double layer charge storage but suffer from poor energy densities due to limited charge storage capabilities. Here we propose a hierarchical functionalization strategy to develop N, S co-doped Co3O4 and N doped high porosity carbon micro-spheres for efficient and durable hybrid supercapacitor. Benefiting from the structural eminence, improved electrical conductivity and high quantity of N content, the heteroatom enriched N, S co-doped Co3O4 and N doped porous carbon spheres demonstrates superior electrochemical performance. Moreover, hybrid supercapacitor cell with N, S co-doped Co3O4 as a cathode and N doped porous carbon spheres as anode deliver a high specific energy of 52 Wh kg-1 at power density of 1462 W kg-1 coupled with the capacity retention of 95 % after 5,000 charge-discharge cycles.Therefore, by improving both anode and cathode simultaneously can be considered an effective approach to enhance energy storage capabilities of hybrid supercapacitors while maintain exceptionally high-power densities.

Exergo and enviro-economic analysis of thermal energy storage assisted finned solar still

The current investigation focuses on improving the performance of a single slope solar still integrated with Phase Change Material as energy storage media. The problem of low thermal conductivity of PCM which hinders the energy storage capability has been addressed by incorporating fins with different profiles into the energy storage unit. Initially, an experimental investigation was conducted and analyzed to assess the effective performance of a Conventional Single Slope Solar Still (CSS) using various water depth levels: 1–4 cm. The optimal basin water depth for testing solar still with energy storage material along with fins was identified as 2 cm. Subsequently, the CSS was subjected to performance enhancement investigation under three different conditions: Case 1 – Solar Still (SS) with PCM storage unit, Case 2 – SS with fins at the PCM storage unit, and Case 3 – SS with fins at the storage unit and a parallel plate attached to the other end of the fins. The experimental results demonstrated the production of fresh water and efficiency improvements are as follows 26.95%, 55.86%, 69.14% and 24.34%, 52.83%, 68.83% for cases I, II, and III, respectively. Further, it was observed that Case III exhibited a lower cost of water production and a shorter payback period compared to CSS. The enviro-economic analysis revealed that the net CO2 emissions (NCEM) and Carbon Credits Earned (CCE) for Case III were 15.60 tons and 312.07 USD respectively against 9.22 tons and 184.31 USD for CSS.

Porous structural battery composite for coordinated integration of mechanical and electrical functionalities

AbstractStructural battery composites (SBCs) represent an emerging multifunctional technology in which materials functionalized with energy storage capabilities are used to build load‐bearing structural components. However, due to the liquid electrolyte contamination in structural battery electrolyte (SBE) and the large volume expansion of active battery materials, the poor interlayer interfacial in multilayer SBCs often causes difficulties in practical use. In this study, a new porous LiFePO4‐graphite SBC is designed and fabricated by independently distributing battery materials and resin matrix on carbon fiber fabric in pattern lattice form to prepare electrodes prepreg. The cured porous composite framework supports the load‐bearing function while limiting the electrochemical reaction in liquid electrolyte within lattices. The electrodes show reversible electric resistance after 3000 bending cycles with radius as small as 10 mm. The mechanical properties enhance significantly with tensile strength of 486.1 MPa and Young's modulus of 9.1 GPa compared to that with a liquid–solid biphasic mixed SBE structure. The SBC also exhibits a favorable capacity of 27.8 mAh/g at 0.1C. This straightforward integration path of mechanical and electrical functionalities is compatible with the manufacturing process of aerospace composite structures, which will provide an efficient and convenient energy supply solution for distributed electronics.Highlights A porous full‐cell structural battery composite (SBC) was designed and fabricated with prepregs. A suspension deposition and volatilization method was developed for robust battery material coating. Electrodes layer exhibited reversible electric resistance after 3000 tensile/bending cycles. The tensile strength and modulus increased significantly compared to the SBC with liquid–solid biphasic mixed structural battery electrolyte. Coordinated integration path was completely compatible with the manufacturing process of aerospace composite structures.

High-performance porous activated carbon derived from Acacia catechu bark as nanoarchitectonics material for supercapacitor applications

BackgroundThe increasing energy demands stemming from the extensive utilization of portable electronic devices are creating a huge energy deficit between demand and supply. In this scenario, it is not only sufficient to pursue and innovate the new renewable energy sources but also requires an ideal device for energy storage and conversion. MethodsIn this work, activated carbon (AC) was prepared from matured bark of Acacia catechu through a series of steps; pre-carbonization, carbonization, and activation. The AC was synthesized at different temperatures (400–800 °C) under inert atmosphere, using orthophosphoric acid as an activator. As-prepared sample (ACBH) was characterized by well-known characterization techniques. Energy storage capability was assessed in terms of Cyclic voltammetry, Galvanostatic charge-discharge, Electrochemical impedance, and Cyclic stability by three-electrode setup. Significant findingsThe ACBH-8 sample demonstrated superior electrochemical performance compared to other samples. The sample ACBH-8, as Negatrode, exhibited a specific capacitance of 282.4 F g−1 at 0.5 A g−1 and retained 95.4 % cyclic stability under 10,000 cycles. The excellent energy storage performance by green-class negatrode materials from the bio-waste substance empowers commercial applications.

Adoption of lib (Lithium Batteries) for hybrid propulsion on small passenger vessel and consequences on damage stability

Nowadays the Hybrid Propulsion is a reality, increasing its diffusion. The main principle is the storing of energy in battery packs to provide energy for the propulsion system of the vessel, aiming the fundament of hybrid propulsion is the use of Li-Ion or Li-Po batteries, with high capability of energy storage (MWh). This good capability has the disadvantage of the explosion risk if exposed to heat. The solutions adopted can impact on damage stability. This paper will analyze the aspects connected with hybrid propulsion in small passenger vessels, considering the State of Art of Rules regarding the fire safety and the possible solutions adopted regarding Lithium batteries. The paper refers to the consequences of adoption of new technology of Lithium batteries developed to be used in maritime application, batteries indicated as “LiB”. The paper is not referring to Lithium metal batteries with the Lithium used as metallic anode and all the consequences on fire risks. The paper is not about the risk of fire due to the battery technology, but is related to the consequences on stability of small vessels if, for security reason a large amount of water is used to cool down the battery packs. The paper will consider the case study of a small passenger ship, examining the general arrangement adopted and the position of the batteries, and the consequences caused by the installation on board of the battery packs. The results will show how the fire safety is important and requires special attention, also in consideration of the various possibilities to contain the fire or prevent the risk of explosion. The aim is to give a suggestion for set new standards for firefighting in presence of large batteries and also to focus on possible problems arising in case of fire on hybrid vessels.

Deep-trap ultraviolet persistent phosphor for advanced optical storage application in bright environments

Extensive research has been conducted on visible-light and longer-wavelength infrared-light storage phosphors, which are utilized as promising rewritable memory media for optical information storage applications in dark environments. However, storage phosphors emitting in the deep ultraviolet spectral region (200–300 nm) are relatively lacking. Here, we report an appealing deep-trap ultraviolet storage phosphor, ScBO3:Bi3+, which exhibits an ultra-narrowband light emission centered at 299 nm with a full width at half maximum (FWHM) of 0.21 eV and excellent X-ray energy storage capabilities. When persistently stimulated by longer-wavelength white/NIR light or heated at elevated temperatures, ScBO3:Bi3+ phosphor exhibits intense and long-lasting ultraviolet luminescence due to the interplay between defect levels and external stimulus, while the natural decay in the dark at room temperature is extremely weak after X-ray irradiation. The impact of the spectral distribution and illuminance of ambient light and ambient temperature on ultraviolet light emission has been studied by comprehensive experimental and theoretical investigations, which elucidate that both O vacancy and Sc interstitial serve as deep electron traps for enhanced and prolonged ultraviolet luminescence upon continuous optical or thermal stimulation. Based on the unique spectral features and trap distribution in ScBO3:Bi3+ phosphor, controllable optical information read-out is demonstrated via external light or heat manipulation, highlighting the great potential of ScBO3:Bi3+ phosphor for advanced optical storage application in bright environments.

Unveiling the Mn3+/ Mn4+ and Ni2+ potential as a high-capacity material for next-generation energy storage devices

In this study, we synthesized MnOx nanowires via hydrothermal methods and explored the impact of nickel (Ni) doping on their morphology and electrochemical properties. We investigated the structural and chemical changes induced by Ni incorporation by utilizing TEM and XPS analyses. Our results revealed that Ni doping influenced the distribution of manganese oxidation states, with 1.6 wt% Ni-doped nanowires exhibiting the optimized condition. Also, we observed a balance between the Mn3+/Mn4+ ratio with the Ni doping. Electrochemical characterization demonstrated enhanced capacity in Ni-MnOx nanowires at the 1.6 wt% Ni doping level. Galvanostatic charge-discharge measurements confirmed the superior performance of this level of Ni doping; moreover, the fabrication of asymmetric supercapacitor cells using these nanowires showed improved energy storage capabilities. The main results showed exceptionally high capacity (955.55 and 383.33 mAh g−1 at 1 and 20 A g−1, respectively) and an excellent rate capability. Cycling stability tests over 8500 cycles demonstrated excellent retention of capacity, underscoring the durability of the optimized Ni-MnOx nanowires, with a retention of 85 % of its initial capacity. Thus, this study emphasizes the significance of Ni doping in MnOx nanowires for enhancing electrochemical performance when the synthetic process is controlled, offering valuable insights for high-performance energy storage device development.

Superior energy storage performance in lead-free SrTiO3 films via ion doping and crystalline optimization

SrTiO3 paraelectric materials exhibit significant potential to be used as lead-free energy storage dielectrics due to their distinctive linear-like polarization behavior. Nonetheless, the application in advanced thin-film capacitors is challenging due to their low polarization strength and structural anomalies, which reduce the breakdown field strength and diminish the energy storage density. This study proposes a synergistic approach that integrates ion doping with the optimization of thermal treatment to enhance the energy storage capabilities of SrTiO3 thin films. Initially, Mn2+ doping in SrTiO3 films mitigates oxygen vacancies and forms Mn2+-VO•• defect dipoles, thereby refining the polarization behavior and reducing the leakage current density. Subsequently, the crystalline degree of SrTi0.99Mn0.01O3 thin films can be regulated by adjusting the annealing temperature. The optimal breakdown field strength of the resultant SrTi0.99Mn0.01O3 films reaches 4681 kV/cm with a 1 mol% Mn2+ doping level, enhancing the recoverable energy storage density (Wrec) to 32.17 J/cm3. Furthermore, the recoverable energy storage density of SrTi0.99Mn0.01O3 films escalates to 36.62 J/cm3 with an efficiency of 80.28 %, upon reducing the annealing temperature to 625 °C. Moreover, SrTi0.99Mn0.01O3 films demonstrate superior thermal stability, frequency stability, and electrical fatigue resistance, underscoring their potential as efficacious materials for film capacitor applications.

Triplet-Sensitized Switching of High-Energy-Density Norbornadienes for Molecular Solar Thermal Energy Storage with Visible Light.

Norbornadiene-based photoswitches have emerged as promising candidates for harnessing and storing solar energy, holding great promise as a viable solution to meet the growing energy demands. Despite their potential, the effectiveness of their direct photochemical conversion into the resulting quadricyclanes has room for improvement owing to (i) moderate quantum yields, (ii) poor overlap with the solar spectrum and (iii) photochemical back reactions. Herein, we present an approach to enhance the performance of such molecular solar thermal energy storage (MOST) systems through the triplet-sensitized conversion of aryl-substituted norbornadienes. Our study combines deep spectroscopic analyses, irradiation experiments, and quantum mechanical calculations to elucidate the energy transfer mechanism and inherent advantages of the resulting MOST systems. We demonstrate remarkable quantum yields using readily available sensitizers under both LED and solar light irradiation, significantly surpassing those achieved through direct excitation with photons of higher energy. In contrast to the conventional approach, light-induced back reactions of the high-energy products do not play any role, allowing quantitative switching within minutes. These results not only underscore the potential of triplet-sensitized MOST systems to leverage the high energy storage capabilities of multistate photoswitches but they might also stimulate the broader usage of sensitization strategies in photochemical energy conversion.

Triplet‐Sensitized Switching of High‐Energy‐Density Norbornadienes for Molecular Solar Thermal Energy Storage with Visible Light

Norbornadiene‐based photoswitches have emerged as promising candidates for harnessing and storing solar energy, holding great promise as a viable solution to meet the growing energy demands. Despite their potential, the effectiveness of their direct photochemical conversion into the resulting quadricyclanes has room for improvement owing to (i) moderate quantum yields, (ii) poor overlap with the solar spectrum and (iii) photochemical back reactions. Herein, we present an approach to enhance the performance of such molecular solar thermal energy storage (MOST) systems through the triplet‐sensitized conversion of aryl‐substituted norbornadienes. Our study combines deep spectroscopic analyses, irradiation experiments, and quantum mechanical calculations to elucidate the energy transfer mechanism and inherent advantages of the resulting MOST systems. We demonstrate remarkable quantum yields using readily available sensitizers under both LED and solar light irradiation, significantly surpassing those achieved through direct excitation with photons of higher energy. In contrast to the conventional approach, light‐induced back reactions of the high‐energy products do not play any role, allowing quantitative switching within minutes. These results not only underscore the potential of triplet‐sensitized MOST systems to leverage the high energy storage capabilities of multistate photoswitches but they might also stimulate the broader usage of sensitization strategies in photochemical energy conversion.

Deep eutectic solvent and laser-reduced graphene oxide: Synergistic effects in ternary nanocomposite supercapacitors

In recent years, flexible supercapacitors (FSCs) have gained considerable attention as reliable power supplies for wearable and portable electronic devices. However, optimizing both energy and power densities remains a challenge and requires effective enhancement of two key components: the electrolyte and the electrode. To address this, we have developed a new and efficient approach to FSC fabrication using a ternary nanocomposite of laser-reduced graphene@polyaniline/NiFe₂O₄(LrGO@Pani-NF) as the electrode and stable polymer hydrogels as the electrolyte. Also, we constructed FSC devices using a cross-linked poly (vinyl alcohol)/deep eutectic solvent (DES) gel electrolyte (PVA/ChCl/EG) and a PVA/Polyaniline/Nickel Ferrite gel electrolyte (PVA/Pani/NF). Among these devices, the LrGO@Pani-NF//LrGO@Pani-NF demonstrated a remarkable energy density of 48.4 Wh kg⁻¹ at 401.8 W kg⁻¹ and a long cycle life of 1000 cycles with 96.9 % capacity retention at 2 mA cm⁻². Furthermore, the supercapacitors assembled with the DES gel exhibited excellent stability at higher voltages, operating within a potential window of −3.0–3.0 V. This work not only enhances FSC electrochemical performance with graphene nanocomposite electrodes but also introduces a novel method for FSC design using conductive, stable gel electrolytes, thereby improving energy storage capabilities under harsh conditions.

Enhanced energy storage performance of Bi(Mg0.5Hf0.5)O3 modified K0.5Na0.5NbO3 relaxor ferroelectric ceramics via synergistic strategy

K0.5Na0.5NbO3 (KNN)-based ceramics with large polarization (Pmax) and submicron grain size are considered as promising candidates for dielectric capacitors. However, the existence of significant remnant polarization (Pr) imposes constraints on achieving high recoverable energy storage density (Wrec) and efficiency (η). In this study, we developed and produced ceramic materials by utilizing the composition of (1-x)K0.5Na0.5NbO3-xBi(Mg0.5Hf0.5)O3 ((1-x)KNN-xBMH, x = 0–0.22), employing a viscous polymer rolling technique. We utilized a combined strategy to improve the energy storage capabilities of these materials by manipulating their crystal structures, inducing relaxor behavior, and minimizing microdefects. As a result, we obtained an optimum Wrec of 3.32 J/cm3 and η of 85.37 % at an electric field strength of 350 kV/cm in the x = 0.18 ceramic. Furthermore, excellent temperature stability was observed within the temperature range 20–120 °C, along with frequency stability across frequencies between 5 and 500 Hz. Moreover, at 200 kV/cm in the same composition (i.e., 0.82KNN-0.18BMH), we obtained a power density value as high as 103.13 MW/cm3, accompanied by a fast discharge speed reaching 30.6 ns. Overall, our results demonstrate that the comprehensive energy storage performances exhibited by the 0.82KNN-0.18BMH ceramic make it highly promising for applications in pulsed-power supply.

One-step self-assembled biomass carbon aerogel/carbon nanotube/cellulose nanofiber composite for supercapacitor flexible electrode

Flexible and exceptionally lightweight energy storage devices are crucial for wearable electronic gadgets. Biomass materials are emerging as ideal flexible electrode components due to their biocompatibility and non-toxic nature. In this study, pineapple leaf fibers were utilized to create activated biomass carbon aerogel (Bio-CAA). Then, carbon nanotubes (CNTs) were integrated as conductive additives, combined with sturdy pineapple leaf cellulose nanofibers (CNFs) to establish a robust 3D framework. Utilizing a one-step self-assembly method, carbon aerogel/carbon nanotube/carbon nanofiber (Bio-CAA/CNT/CNF) flexible composite electrode materials were successfully synthesized. The porous structure of Bio-CAA effectively minimized the aggregation of CNTs, thereby significantly enhancing the electrochemical performance of the electrode material. The characterization indicated that the carbon aerogel composite exhibited a high specific surface area (684.275 m2 g−1) after tablet compression. The material was light yet robust, capable of being bent arbitrarily and recovering its original shape and withstanding 400 Kpa of pressure at an 88 % strain rate, demonstrating excellent mechanical properties. In a three-electrode system, the Bio-CAA/CNT/CNF = 19:1:1 based electrode exhibited a capacitance of 481 F g−1 at a current density of 1 A g−1. The CAA/CNT/CNF = 19:1:1 based solid symmetric supercapacitor (SSC) displayed excellent cycling stability, preserving 91.7 % capacitance after 10,000 cycles at a current density of 5 A g−1. It achieved an energy density of 39.63 Wh kg−1 at a power density of 500 W kg−1. This biomass-derived carbon aerogel-based composite material demonstrates exceptional energy storage capabilities, and its lightweight attributes make it highly suitable for use in flexible displays, wearable devices, and related fields.

Development and evaluation of alkali-activated concrete with thermal energy storage capability for energy geostructures

Energy geostructures, such as energy piles, tunnels, and continuous underground walls, offer an innovative solution for harnessing shallow geothermal energy while serving structural functions. However, their limited energy density often leads to inefficient heat exchange and fluctuations in structural stability, along with significant challenges related to ion erosion in practical applications. This study introduces Alkali-Activated Concrete with Thermal Energy Storage Capability (AAC-TESC), which incorporates Phase Change Material (PCM) with high thermal storage density into Alkali-Activated Concrete (AAC), for energy geostructures. For the first time, the mechanical properties, volume stability, and durability of AAC-TESC under the operational conditions of energy geostructures were systematically investigated. The results reveal that the inclusion of Thermal Energy Storage Aggregate (TESA) containing PCM significantly reduces temperature-induced deformations by 44.8–76.9 % while maintaining compressive strength within the range of 30–60 MPa, making AAC-TESC highly suitable for energy geostructure applications. Additionally, AAC-TESC shows enhanced resistance to chloride diffusion, attributed to increased thermal cycling and lower operating temperature, potentially reducing its activation energy. This study offers valuable insights into the potential of AAC-TESC to improve the volume stability and durability of energy geostructures, presenting a sustainable solution to contemporary construction challenges.

Ti3C2Tx MXene/Graphene hybrid frameworks for constructing thermally conductive phase change composites with solar-thermal conversion ability

Application of three-dimensional (3D) carbon framework in phase change material (PCM) has aroused a tremendous interest. However, implementing a high alignment carbon framework with low interfacial thermal resistance (ITR) remain challenging. Herein, we demonstrated a synergetic effect strategy by Ti3C2Tx MXene and graphene nanoplate (GNP) to achieve a 3D thermally conductive framework with high alignment skeleton and low filler-to-filler ITR. Typically, the 3D anisotropic carbon framework is fabricated by unidirectional ice template freezing cellulose nanofibers (CNF)/GNP solution with the assistance of MXene. The abundant functional groups of MXene and the similar layered structure promote the dispersion stability of GNP in CNF aqueous solution, resulting in the significant improvement in GNP alignment and the filler-to-filler ITR. Therefore, the final phase change composites obtained by impregnating polyethylene glycol (PEG) into the framework achieves a satisfactory thermal conductivity (TC) of up to 3.49 W/m K at only 6.25 vol% filler loading. Combining the solar-thermal conversion ability of graphene and MXene, the PCM reveals a rapid energy conversion, transfer and storage capability. More importantly, the phase change enthalpy of the PCM can be as high as 164.3 J/g, with little change even after 50 heating-cooling cycles, and the existence of carbon framework can effectively prevent the leakage phenomenon in solid-liquid conversion process, ensuring its shape stability.

Investigating swastika fins to enhance heat transfer and melting process of nano-enhanced phase change materials units

The ability of nano-enhanced phase change materials (NePCM) to store thermal energy has garnered the interest of scientists. An approach to enhancing thermal conductivity involves the implementation of novel fins that facilitate a more rapid PCM melting process. The present investigation assessed the efficacy of eight distinct fin configurations in augmenting the thermal properties of NePCM. Four occurrences featured swastika fins, whereas the remaining instances exhibited a 45-degree tilt angle. The enthalpy-porosity method was implemented to simulate heat transfer and melting process. The present research investigates the effects of fin tilt angles and swastika fins on the NePCM-thermal energy storage (TES) unit's mean temperature, liquid percentage, and thermal energy storage. Compared to the straight fins (Case 1), the long-arm swastika fins (Case 4) decreased the melting time by a factor of 2.3. In addition, Case 4 demonstrated exceptional thermal energy storage capabilities. Case 7 demonstrated that the tilting angle significantly affected the melting time, with a reduction of 34.9 %, compared to the non-tilted swastika fins utilized in Case 2. However, the increase in the fins' length was more substantial. According to the findings of this study, Case 4 is the optimal fin configuration for NePCM-TES.

Analytical investigation of interleaved input/output parallel DAB converter for grid scale battery storage

With the surge of integration of intermittent renewable energy sources into the grid the installation of large scale battery energy storage is rising at a rapid rate to support the power system. The grid scale battery storage needs to be scalable with varying power system requirements. Parallel connected modular dual active bridge (DAB) converter with high frequency transformers interface can facilitate adjustable large power flow for grid scale battery storage. The high gain between LV and HV side can be achieved using isolated high frequency transformers and parallelism of the DAB converter with efficient and smooth bidirectional power transfer capability. In this paper, a generalized interleaving operation (ILO) on both input and output parallel connected DAB (IOPDAB) converter has been proposed for large energy storage capability and to enable improved quality of power flow. The generalized expressions of peak currents, average circulating current and active power flow, has been developed for the IOPDAB converter with n-parallel connected DAB modules. A detailed analytical investigation has been carried out to show the improved currents profile in both input and output sides in the interleaved mode. The operating performance of the IOPDAB converter has been shown using PSCAD/EMTDC software based simulation. The results are verified through laboratory experimental setup with two interleaved I/O parallel DAB using Spartan 3AN FPGA processor as controller. A performance comparison has been done with the non-interleaving operation (NILO) and interleaving operation (ILO) modes, and it is shown that the ILO mode has better performance in terms of efficiency, Input/output ripple current reduction, increased ripple frequency and circulating current minimization.

Balancing the Co‐Solvent Content in High Entropy Aqueous Electrolytes to Obtain 2.2 V Symmetric Supercapacitors

AbstractThe energy storage capability of supercapacitors (SCs) strongly depend on the operating cell voltage of the electrolytes of choice. In this regard, the inherent distinct electrochemical stability of cations and anions is a factor of relevance for the operating cell voltage. The use of double salts sharing one ion has been described as an approach to circumvent this problem, but whether modifying the solvation structure of cations and anions with different solvent molecules (coordinating and/or non‐coordinating) could help balance their electrochemical stability in SCs has not yet been fully addressed. In this work, electrolytes are prepared by combining solvent mixtures and double salts, specifically 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF4) in mixtures of water (H2O) and dimethysulfoxide (DMSO) as coordinating co‐solvents and acetonitrile (CH3CN) as a weakly coordinating one. It is found that the presence of this latter one helped to enhanced the cation solvation structure (above 9). This increase of the entropic features allows operating at cell voltages of up to 2.2 V and the subsequent enhancement of the energy storage capabilities and capacitance retentions (up to 15 Wh kg−1 and ≈87% after 10 000 cycles, respectively).