Large Energy Storage Capacity Research Articles

Double layer capacitors in dye sensitized solar cells with large charge and energy storage capacity and controlled shape of output voltage signals.

The output signals in natural dyes-based solar cells (DSSC) can be either rising or decaying depending on the type of ions present in the system; these ions called added ions, are introduced by the additives: mordant and brighteners. The photon-dye interaction produces electrons, which eventually reach the electrode giving place to a superficially charged electrode in contact with an electrolyte where are the added ions. This combination produces, automatically, an electrical double-layer EDL structure which has important effects on the performance of the system: a) the added ions control, to a large extent, the initial shape of the output signal, giving rise to rising or decaying profiles; b) it is possible to store large amounts of energy and charge at high electric fields. This structure is found in many other systems that have a surface charged in contact with an electrolyte like piezoelectric materials in human body. This assertion was supported by determining important parameters such as the force between charged surfaces on both sides of the interface, the charge density, the energy density, and the capacitance. The Debye length has very small values then, many important quantities depend on this; it is possible to obtain large values for energy UDL ~ 3.6x105 Jm-3 and charge density ρDL ≈ 1.1x107 Cm-3 for double layer capacitors; these values are orders of magnitude larger than the corresponding values for electrostatic capacitors: Uelec ≈ 4.5x10-3 Jm-3 and ρelec ≈ 1.2 Cm-3. A non-linear model was also developed to fit unstable oscillations found in the output profiles produced by abrupt lighting.

The incorporation of cobalt ions into hydroxyapatite nanostructure for a novel range of electrochemical energy storage applications

Supercapacitors (SCs) have garnered extensive attention for their notable advantages, including extended cycle life, high energy density, and cost-effectiveness. Due to their large energy storage capacity and high output power, the development of pseudocapacitive materials for energy-oriented applications has been of great importance. The integration of nanoscale active materials in batteries results in faster redox kinetics. Consequently, alters the material's electrochemical characteristics from battery-like to pseudocapacitive-like behavior driven by enhanced surface area and reduced diffusion routes. This study aims to investigate the efficacy of pure hydroxyapatite and Co2+-doped hydroxyapatite (HAP) nanoparticles as electrode materials for SCs. The pure HAP and Co2+-doped HAP nanoparticles were synthesized via the Sol-Gel method. Electrochemical techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the electrochemical behavior of the developed electrode. The highest values of specific capacitance (Csp) and energy density for the SC with Co2+-doped HAP nanoparticles electrode were obtained at 324 F g−1 and 145.8 Wh kg−1, respectively, at a current density of 1.2 A g−1. According to the data above, Co2+-doped HAP nanoparticles can be used as a substitute to improve electrochemical performance in energy storage applications.

Multi-objective capacity configuration optimization of a nuclear-renewable hybrid system

Integrating the energy storage and the base-load energy can be an efficient solution to cover the fluctuation of renewable energy. A nuclear-renewable hybrid energy system consisting of a small modular thorium molten salt reactor, solar photovoltaics, wind turbines, thermal energy storage and battery storage with two operation modes is proposed to meet the community load demand. The methodology combining multi-objective evolutionary algorithms with multi-criteria decision-making method is used to identify the optimal operation mode and gain the optimal configuration of the proposed nuclear-renewable hybrid energy system. In the first stage, the multi-objective evolutionary algorithm with better performance is utilized to gain Pareto solutions to minimize the levelized cost of energy while ensuring an acceptable level of deficiency of power supply probability. In the second stage, the multi-criteria decision-making method is adopted to select the best solution from the obtained Pareto frontiers. The optimization results demonstrate that the nondominated sorting genetic algorithm has the best performance compared with other algorithms and the operation mode with battery discharged first is more cost competitive. It is concluded from the results analysis that the selection of optimal mode is influenced by seasonal variation that contributes to large energy storage capacity requirement.

A Novel Differentiated Control Strategy for an Energy Storage System That Minimizes Battery Aging Cost Based on Multiple Health Features

In large-capacity energy storage systems, instructions are decomposed typically using an equalized power distribution strategy, where clusters/modules operate at the same power and durations. When dispatching shifts from stable single conditions to intricate coupled conditions, this distribution strategy inevitably results in increased inconsistency and hastened system aging. This paper presents a novel differentiated power distribution strategy comprising three control variables: the rotation status, and the operating boundaries for both depth of discharge (DOD) and C-rates (C) within a control period. The proposed strategy integrates an aging cost prediction model developed to express the mapping relationship between these control variables and aging costs. Additionally, it incorporates the multi-colony particle swarm optimization (Mc-PSO) algorithm into the optimization model to minimize aging costs. The aging cost prediction model consists of three functions: predicting health features (HFs) based on the cumulative charge/discharge throughput quantity and operating boundaries, characterizing HFs as comprehensive scores, and calculating aging costs using both comprehensive scores and residual equipment value. Further, we elaborated on the engineering application process for the proposed control strategy. In the simulation scenarios, this strategy prolonged the service life by 14.62%, reduced the overall aging cost by 6.61%, and improved module consistency by 21.98%, compared with the traditional equalized distribution strategy. In summary, the proposed strategy proves effective in elongating service life, reducing overall aging costs, and increasing the benefit of energy storage systems in particular application scenarios.

Silicon photonics-based high-energy passively Q-switched laser

Chip-scale, high-energy optical pulse generation is becoming increasingly important as integrated optics expands into space and medical applications where miniaturization is needed. Q-switching of the laser cavity was historically the first technique to generate high-energy pulses, and typically such systems are in the realm of large bench-top solid-state lasers and fibre lasers, especially in the long wavelength range >1.8 µm, thanks to their large energy storage capacity. However, in integrated photonics, the very property of tight mode confinement that enables a small form factor becomes an impediment to high-energy applications owing to small optical mode cross-sections. Here we demonstrate a high-energy silicon photonics-based passively Q-switched laser with a compact footprint using a rare-earth gain-based large-mode-area waveguide. We demonstrate high on-chip output pulse energies of >150 nJ and 250 ns pulse duration in a single transverse fundamental mode in the retina-safe spectral region (1.9 µm), with a slope efficiency of ~40% in a footprint of ~9 mm2. The high-energy pulse generation demonstrated in this work is comparable to or in many cases exceeds that of Q-switched fibre lasers. This bodes well for field applications in medicine and space.

Research on Design Parameters of Pumped Storage Power Station Based on Different Geographical Locations

Energy storage technology plays an extremely crucial role in the transition of the current social energy structure to renewable energy. Energy storage technology with high efficiency, safety and long storage period has become the key to breaking through the limitations of renewable energy utilization. As one of the most widely used large-scale energy storage technologies, pumped storage hydropower (PSH) has the advantages of high efficiency and large energy storage capacity. It has good development potential in countries with abundant water resources, but there are also problems such as high initial investment, high cost, construction. The cycle is long and largely limited by geographical conditions. This paper analyzes the parameters of PSH station in different geographical locations, compares their differences based on the cost per unit of electricity of the whole life cycle, explores the relationship between the location of pumped storage power plants and the cost of power per unit of electricity, and provides a basis for promoting the development of this technology. Provide effective technical support for development.

Electrochemically Triggered Self-Adaptive Reconstruction of an all-Purpose Electrode for Photothermally Enhanced Capacitors.

Large-capacity energy storage devices are attracting widespread research attention. However, the decreased capacity of these devices due to cold weather is a huge obstacle for their practical use. In this study, an electrochemical self-adaptive reconstructed Cux S/Cu(OH)2 -based symmetric energy storage device is proposed. This device provides a satisfactorily enhanced photothermal capacity under solar irradiation. After electrochemical reconstruction treatment, the morphological structure is rearranged and the Cux S component is partially converted to electrochemically active Cu(OH)2 with the introduction of a large number of active sites. The resulting Cux S/Cu(OH)2 electrode provides a significant capacitance of 115.2 F cm-2 at 5mA cm-2 . More importantly, its wide working potential range and superior photo-to-thermal conversion ability endow Cux S/Cu(OH)2 with superb performance as full-purpose photothermally enhanced capacitance electrodes. Under solar irradiation, the surface temperature of Cux S/Cu(OH)2 is elevated by 76.6°C in only 30 s, and the capacitance is boosted to 230.4% of the original capacitance at a low temperature. Furthermore, the assembled symmetric energy storage device also delivers a photothermal capacitance enhancement of 200.3% under 15min solar irradiation.

Demonstration and thermal equilibrium analysis of a 10 kJ capacity energy storage coil made of MgB2 with liquid hydrogen indirect cooling

We have demonstrated an advanced superconducting power conditioning system, in which a superconducting magnetic energy storage (SMES) device, a generator based on a fuel cell (FC), and an electrolyzer are used to compensate for electricity fluctuations over a wide frequency range, combined with a liquid hydrogen storage system to both cool the SMES and provide pure hydrogen gas to the FC and other gas-dependent systems. To manufacture the coils for the SMES, we used MgB2, whose critical temperature is below the boiling temperature of hydrogen. We developed a 10 kJ SMES coil system indirectly cooled by liquid hydrogen using thermosyphon passive heat exchange to isolate the flammable hydrogen from the electrical components. We performed a successful demonstration of this system for both DC and AC currents ramped at different rates. In the present study, we use computer simulations involving heat balance equations to evaluate the stability of the system. The results obtained are expected to lead to the design of future large-capacity energy storage systems, such as the MJ class, which offer comparable performance to conventional NbTi SMES devices.

Electroactive site enriched battery-type worm-like cobalt tungstate nanoarchitecture electrode material for performance-enhanced hybrid supercapacitor

The supercapacitor performances of stable and highly efficient electrode materials crucially depend on their physicochemical parameters, which are influenced by the preparation conditions and techniques. Herein, the worm-like CoWO4 (CWO) nanoarchitecture is achieved through a facile hydrothermal method followed by pyrolysis. The effect of pyrolysis temperature on the physicochemical properties, such as crystallinity, surface area, porosity, particle size, and morphology of the prepared CWO nanomaterials, is examined. From these observations, the pyrolyzing temperature significantly impacts the physicochemical characteristics and the associated electrochemical performances. Further, the final product's crystallite size increases, and surface area concomitantly fall from 16 to 34 nm and 26.1–12.9 m2 g−1, respectively, as the pyrolyzing process is increased from 400 to 600 °C. The distinct morphological feature of worm-like CWO-A nanostructure pyrolyzed at 400 °C is advantageous to have effective charge transfer and large energy storage capacity. Markedly, the worm-like CWO-A electrode depicts a superior specific capacity of 445 and 284 C g−1 at 1 and 20 A g−1, respectively, suggesting an excellent rate performance. Moreover, the constructed hybrid supercapacitor (CWO-A//AC) attains a maximum energy density of 41.38 Wh kg−1 at a power density of 627.42 W kg−1 with an outstanding long-term cyclic retention and ∼9.3% of capacity loss for 10,000 cycles. Thus, this study highlights that the distinct worm-like CWO-A nanostructure could be a suitable electrode material for supercapacitor applications.

Embedment of hollow SiO2 spheres into flower-like Ti3C2Tx MXene framework with decoration of carbon for efficient microwave absorption

With the advancement of modern microwave communication technologies, the development of lightweight absorption materials with high capacity and a wide absorption bandwidth has aroused great interest. Despite its low density, strong temperature resistance, high strength, and great electromagnetic energy storage capacity, SiO2 still has a long way to go in terms of efficiently dissipating microwaves due to its low polarization loss and conductive loss. Herein, the 3D sandwich-like M-Ti3C2Tx @SiO2 @C hybrids are synthesized by inserting SiO2 hollow spheres into the flower-like Ti3C2Tx MXene framework and decorating with carbon. SiO2 hollow spheres securely attached on monolayer Ti3C2Tx MXene nanosheets provide large electromagnetic energy storage capacity as well as additional interfacial polarization. The 3D flower-like Ti3C2Tx MXene framework and carbon coating ensure high conductive loss. The 3D sandwich-like M-Ti3C2Tx @SiO2 @C hybrids shows excellent microwave absorption performance. Under 40 wt% filler loadings, the 3D sandwich-like M-Ti3C2Tx @SiO2 @C hybrids deliver minimum reflection loss of − 43.97 dB at 4.5 mm thickness. At 1.5 mm thickness, their effective absorption band expands to 4.12 GHz. The facile and scalable synthesis strategy offers a novel design concept for the commercialization of high-performance microwave absorbers.

Role of graded microstructure and electrolyte distribution in electrochemical capacitance of compressible three-dimensional carbon nanotubes-polymer foam based supercapacitor

Three-dimensional microstructure of carbon materials has a prime importance in supercapacitor for energy storage. Carbon nanotubes (CNT) provide microstructurally porous structure via entangled nodes that dynamically changes with the uniaxial compression. A unique graded CNT-polymer based three-dimensional compressible cellular foam is used as an electrode material for the solid-state supercapacitor. A direct correlation was established between the applied strain and resulting electrochemical capacitance when the foam electrode was soaked and unsoaked in the electrolyte. In a novel finding, unsoaked electrodes revealed in an extraordinary enhancement of ∼1216% in gravimetric capacitance measured at a uniaxial strain of 80% and to no surprise, the electrochemical capacitance of electrolyte-soaked electrodes remained nearly invariant from its uncompressed state. The response of electrochemical capacitance under compression is also observed varying with the mode of compression i.e. quasi-static versus pre-compressed state to a targeted strain. The role of graded microstructure during uniaxial compression was verified by using as-grown CNT mat for the electrodes of a supercapacitor. The results demonstrated a dominating contribution of dynamic variation in the density of nodes in the compressed CNT mat. The impact of macroscopic variation on the response of electrochemical capacitance of a compressed cellular CNT-polymer foam was further understood using the separators of varying pore sizes. Our results pave the way to engineer the three-dimensional compressible cellular structures for extraordinarily large energy storage capacity.

Research on Electromagnetic System of Large Capacity Energy Storage Flywheel

A large capacity and high power flywheel energy storage system (FESS) is developed and applied to wind farms, focusing on the high efficiency design of the important electromagnetic components of the FESS, such as motor/generator, radial magnetic bearing (RMB) and axial magnetic bearing (AMB). Firstly, a axial flux permanent magnet synchronous machine (AFPMSM) based on soft magnetic composite material (SMC) is designed. Then, considering the structure of FESS and machine, a permanent magnet biased radial magnetic bearing (PMRMB) and a HALBACH axial passive magnetic bearing (PMB) is proposed which have the advantages of low power consumption and large bearing capacity, then the analyses are carried out according to the load capacity requirements. Finally, the flywheel prototype is fabricated and tested. The experimental results verify the relevant theoretical analysis, and finally can achieve stable and reliable operation.

Structure and Optimization Design of Cup Winding Permanent Magnet Synchronous Machine in Flywheel Energy Storage System

A cup winding permanent magnet synchronous machine(PMSM) is proposed in the application of large capacity energy storage flywheel (FESS), which can effectively improve the efficiency of the FESS and reduce the axial height of the flywheel. Firstly, the structure of the whole flywheel system and the cup winding PMSM are given. Secondly, the preliminary design scheme of the machine is obtained, and the effect of changing each parameter on the machine performance is analyzed. On this basis, a new optimization strategy combining BP-ANNs, GA and multi-objective PSO algorithm is proposed to optimize the efficiency and volume characteristics of the machine, and the results of the optimization are compared with the preliminary scheme to verify the correctness of the optimization method.

Enhanced Thermal Conductivity of Phase Change Microcapsules Based on Boron Nitride/Graphene Oxide Composite Sheets

Large energy storage capacity and high heat conduction are very important for phase change materials. Phase change microcapsules (PCMCs) were synthesized through in situ polymerization by using paraffin as the core material. The melamine–formaldehyde (MF) polymer shell of PCMCs was modified with boron nitride/graphene oxide composite sheets (BN/GO CSs) to improve thermal conduction. The preparation condition of BN/GO CSs through the self-assembly process and the synthesis process of composite PCMCs (CPCMCs) in the presence of BN/GO CSs were systematically investigated. The thermal conductivity of CPCMCs synthesized under the optimized condition significantly increased about 190% relative to the incorporated paraffin. Promisingly, the introduction of BN/GO CSs hardly influenced the encapsulation process, allowing high encapsulation rate (>93%) and high phase change enthalpy (∼200 J·g–1). This work is an enlightening complementarity to the very limited research attempts that incorporating multiple fillers in PCMCs. We postulated and proved the synergistic effect of BN/GO CSs and their advantages in improving the thermal conductivity of the resultant PCMCs without scarifying the essential heat storage capacity. We envision that the insights and the CPCMCs synthesized can be applied in a range of material designs for energy and electronic applications.

Energy storage device based on a hybrid system of a CO2 heat pump cycle and a CO2 hydrate heat cycle

A new large-capacity energy storage device (with a storage capacity of several megawatt-hours or more) based on a hybrid cycle of a CO2 heat pump cycle and a CO2 hydrate heat cycle is investigated using an experiment-based numerical analysis. In the charging mode of the CO2 heat pump cycle, the work of the compression process is input with surplus electricity from renewable energy sources. Liquid CO2 is stored in a tank after the condensation process. In the discharge (power generation) mode, the liquid CO2 stored in the tank is heated by outside air, and the expanded gas is supplied to the expander, which then operates the generator to obtain electricity from the expansion work. However, if the outside temperature is low, the expansion of liquid CO2 will be insufficient. The abovementioned CO2 hydrate heat cycle is added to the CO2 heat pump cycle. The resulting energy volume density of the proposed system is 80–140 kWh/m3, with a charge–discharge efficiency of 60%–106%, and the equipment costs should be similar to those of pumped storage. At ambient temperatures of <10 °C, the hybrid system with energy storage by gas hydrates is more effective, with a higher energy volume density and charge–discharge efficiency than previous systems.

Study on Energy Storage and Cost Saving Scheme of Traction Substation

Based on the energy-saving and economical operation requirements of high-speed railways, the traction power supply system adopts large-capacity energy storage devices. The paper takes the measured data of a traction substation as an example to compare the energy-saving effects of the two energy storage schemes and give suggestions.

Elaborately designed 3D honeycomb M−Ti3C2Tx@MoS2@C heterostructures as advanced microwave absorbers

Microwave absorption materials with lightweight, high absorption performance, and a broad absorption bandwidth are becoming increasingly popular due to the rapid advancements in wearable devices and portable electronic products. The two-dimensional Ti3C2Tx MXene is a highly promising electromagnetic shielding material thanks to its excellent conductivity, rich functional groups and customizable surface chemistry. However, the low dielectric loss of this material restricts its applications in microwave absorption. Herein, 3D honeycomb M−Ti3C2Tx@MoS2@C heterostructures were synthesized by simple hydrothermal and secondary annealing methods. Vertically assembled MoS2 nanosheets ensured a large electromagnetic energy storage capacity and promoted additional interfacial polarization. The honeycomb surface structure facilitated the electromagnetic wave attenuation through multiple reflections. The carbon coating and M−Ti3C2Tx matrix resulted in high conductive loss in the final products. The three-dimensional honeycomb M−Ti3C2Tx@MoS2@C heterostructures demonstrated exceptional microwave absorption performance. When filler loadings reached 40 wt%, the 3D honeycomb M−Ti3C2Tx@MoS2@C heterostructures delivered a minimum reflection loss of −47.55 dB at a thickness of 4.0 mm, with the added benefit of increasing the effective absorption bandwidth to 4.02 GHz. These findings paved the way for the commercialization of advanced microwave absorbers.

Bidirectional Power Control Strategy for Super Capacitor Energy Storage System based on MMC DC-DC Converter

Abstract: In order to equip more high-energy pulse loads and improve power supply reliability, the vessel integrated power system shows an increasing demand for high-voltage and large-capacity energy storage systems. Based on this background, this paper focuses on a super capacitor energy storage system based on a DC-DC converter. This paper analyzes the different topology of Hybrid Energy Storage System (HESS) and Demand Management System using HESS. Taking into account the shortcomings of the traditional bidirectional power control strategy, this paper proposes a control strategy where the HESS module of each branch independently controls the voltage of the sub-module capacitor. The outputs are validated and verified using MATLAB Simulink platform.

Design and optimization of composite phase change material for cylindrical thermal energy storage

Phase change materials store thermal energy in the form of latent heat, and are often integrated with high thermal conductivity metals to make composites that have both high power density and large energy storage capacity. In this study, we provide a theoretical framework to design and optimize cylindrical composites with three figures of merit – minimization of temperature rise, maximization of the effective volumetric heat capacity and maximization of the effective heat capacity based on mass. We validate the figures of merit experimentally by 3D printing AlSi12 alloy and using octadecane as phase change material for a heat flux of 13.3 Wcm−2 and heating time of 10 s. The metal component volume fractions in the printed structures vary from 15% to 70% for straight fin structures, 10% to 70% for the SC lattice structures, and 20% to 70% for branching fin structures. When minimizing temperature rise, the optimum volume fraction of thermally conductive material is 0.5–0.7. When maximizing the effective volumetric heat capacity, the optimum volume fraction for the high conductivity material is 0.3–0.5. Finally, when maximizing the effective heat capacity by mass in cylindrical composites, the optimum volume fraction for the high conductivity material is 0.2–0.3. Importantly, the optimum values depend on the applied thermal load, which is not captured in existing figures of merit for thermal storage systems. The volumetric and mass based heat capacity values of the optimized composites identified in this study are at least 10x higher when compared to single component PCMs that are widely used for volumetric and mass based thermal storage systems. The figures of merit developed here can assess the performance of most composite PCM systems and help to design future cylindrical composites while accounting for the thermal loads specific to the thermal storage application.

Enhancement in Thermal Properties of Organic Phase Change Material (Paraffin) via TiO2 Foam Doping

Phase change materials (PCM) can absorb or release a huge amount of latent heat in accordance with the increase or decrease of the surrounding temperature. Among all the studied PCMs, organic PCM paraffin has been chosen due to the large energy storage capacity for thermal energy storage (TES). The present work introduces a thermally modified phase change material by TiO2 foam impregnation in paraffin. Three TiO2/paraffin PCM composites TPCM1, TPCM2, and TPCM3 containing 10 wt.%, 15 wt.%, and 20 wt.% of TiO2 foam with paraffin have been successfully synthesized for thermal energy storage. The porous TiO2 foam can provide a high paraffin loading capacity of up to 80 % (TPCM3) due to hollow cavities. TiO2 foam is uniformly distributed over the inner and outer surface of the paraffin as a nano additive to enhance the thermal conductivity (TC) of the composite PCM. The structural, morphological, and thermal study revealed that doping of the supporting material has potentially modified all the criteria of PCM composite for TES. The highest leakage-proof result was obtained for 20 wt.% of TiO2 foam impregnated composite (TPCM3) by analysing mass loss across 500 thermal cycles in an oven at 80°C. The thermal reliability of the TPCM3 composite has also been investigated after 500 thermal cycles. The TPCM3 composite maintains its crystalline nature with homogeneous dispersion and thermal stability without affecting the thermal and chemical properties of the PCM. The latent heat of the TPCM3 composite reached 182.87 J/g, and the thermal conductivity has been calculated at 0.71 W/m-K, which is 3.73 times higher than paraffin. The results concluded that synthesized TPCM3 composite could be a potential candidate for TES due to chemical and physical compatibility, easy synthesis process, good thermal and chemical reliability, and acceptable energy storage capacity with enhanced thermal conductivity.