High Energy Storage Capacity Research Articles

Polyethylene Glycol Confined in SiO2-Modified Expanded Graphite as Novel Form-Stable Phase Change Materials for Thermal Energy Storage.

Form-stable phase change materials (FSPCMs) composed of poly(ethylene glycol) (PEG) encapsulated in SiO2-modified expanded graphite (EG@SiO2) were prepared and investigated for thermal energy storage behaviors. The modification of SiO2 on EG was done using a simple sol-gel method, and then the resulting EG@SiO2 was introduced to confine PEG at varying content (60-90 wt %). Surface properties (including microstructure, morphology, and functional groups), PEG adsorptivity, leakage-proof ability, and thermal energy storage of the prepared materials were thoroughly characterized and discussed. The EG@SiO2 with 15 wt % SiO2 outstandingly adsorbed PEG as compared to the pristine EG, showing up >80 wt % of PEG. As a result, PEG was well stabilized in EG@SiO2 porous network without leakage, owing to capillary force, surface tension, and hydrogen bonding interactions. The optimal 80 wt % PEG/EG@SiO2 composite possessed high crystallinity (93.5%), high thermal energy storage capacity (132.5 J/g), and excellent thermal conductivity (4.086 W/m·K). In addition, it exhibited good cycling durability after 500 repeated melting/crystallization cycles. The high thermal efficacy and inexpensiveness would make the PEG/EG@SiO2 FSPCMs suitable for scale-up applications in thermal energy storage.

Thermophysical properties and solar thermal energy storage performance of phase change composites manufactured by vat photopolymerization 3D printing technique

Phase change materials (PCMs) refer to a group of semi-solid/liquid materials that have high energy storage capacity that are released during the phase transitioning period. Although the impact of utilizing PCMs are considerable, often suitable conservation from leakage is a major issue for these materials' uses. Considering this issue, this study incorporates a Vat Photopolymerization technique to print a composite resin filament containing lauric acid (LA) used as a PCM. LA were mixed with resin in four different proportions of 20, 30, 40 and 50 vol%, and then printed for testing. To thoroughly analyze the characteristics of the resin/LA composites that were manufactured, a range of tests focusing on mechanical, thermal, and microstructural aspects were carried out on the produced samples. Additionally, solar thermoregulation properties were also investigated using a specifically developed testing instrument. The obtained results show that the highest latent heat enthalpy value (83.7 J/g) was found in 50 % LA added composites that also contained a homogeneous internal structure compared to undoped resin materials. Although 50 % LA additive provides superior heat energy storage, it causes a decrease in mechanical properties, since the resin has five times higher tensile strength than that of LA. Nonetheless, the results show that PCMs (specifically LA, in this case), can be 3D printed in real-time with resins without concerns over the leakage problem. This novel use of PCMs can significantly improve the leaking issue and provide a solid mean for energy storage purposes that can support major insulating and energy savings.

Partially unzipped carbon nanotubes-CaCu3Ti4O12/ferroelectric polymer nanodielectric composites with high permittivity, high energy storage capacity and low dielectric loss

Partially unzipped carbon nanotubes-CaCu3Ti4O12/ferroelectric polymer nanodielectric composites with high permittivity, high energy storage capacity and low dielectric loss

High-energy storage capacity of cellulose nanofiber supercapacitors using bound water

The performance of electric double-layer capacitors and lithium-ion batteries deteriorates with increasing humidity. The desirable effect of bound water on the energy-storage properties of physically dry cellulose nanofiber (Na-ACF) supercapacitors with sodium (Na) carboxylate radicals was investigated using infrared and near-infrared spectroscopy, and nuclear magnetic resonance spectroscopy, alternating current impedance analyses, and first-principles calculations. The storage capacity decreased gradually upon heating to 423 K and reached zero upon exceeding 483 K, accompanied by increasing electrical resistance, forming a distorted semicircle in Nyquist diagram and drawing the phase angle to zero in Bode diagram. This is attributed to the water in the hydration gel bound to the Na+-ions that cross-link the cellulose chains, evaporating as the temperature increases, and finally becoming Na2O. The increased band-gap energy from the increase in bound water prevents leakage from the supercapacitor. In contrast to ordinary batteries, bound water is necessary for developing Na-ACF supercapacitors.

Microencapsulation study of bioderived phase change material beeswax with ethyl cellulose shell for thermal energy storage applications

ABSTRACT The commercial shape-stabilized phase change material (PCM) products are obtained from synthetic raw materials. These materials are produced from carbon-intensive petroleum-refining processes. The carbon footprint can be minimized by using biobased products. Beeswax is a naturally available PCM with high phase transition enthalpy comparable to synthetic PCMs. In the previous literature studies, beeswax was shape-stabilized with synthetic materials. In the present study, beeswax was shape-stabilized with biopolymer ethyl cellulose by emulsion solvent evaporation method. The study aims to determine optimum microencapsulation process parameter levels for synthesizing microcapsules with high thermal energy storage (TES) capacity. The optimized process parameters for formulating microcapsules were 60:40 core/shell ratio, 2% PVA concentration, ethyl acetate solvent, and 40°C evaporation temperature. The microcapsules prepared with optimized process parameters were characterized using differential scanning calorimeter (DSC), T-history analysis, Fourier transform infrared (FTIR) spectroscope, and scanning electron microscope (SEM). FTIR and SEM analysis confirmed ethyl cellulose shell formation over the beeswax core. The optimized MPCM formulation possesses 115.8 J/g melting enthalpy with peak phase transition temperature of 58.2°C and thermal conductivity of 0.219 W/mK. The porous structure of the shell reduced melting enthalpy of optimized MPCM formulation to 84.6 J/g after 50 thermal cycles. The synthesized microcapsules comprise sustainable materials and have high TES capacity. The fabricated microcapsules can be used as TES additive in composite and coating formulations in food packaging.

Fabrication of Activated Multiporous Carbon Nanofibers Using Vacuum Plasma for High-Capacity Energy Storage

Porous carbon nanofibers are widely used as supercapacitor electrode materials due to their excellent physical adsorption/desorption operation and smooth transport of ions. The acid/base activation method is commonly used to generate micropores on the surface of carbon nanofibers, but controlling the activation level and minimizing the release of harmful chemicals pose challenges. This study proposed a method for producing activated multiporous carbon nanofibers that is easier to operate and more environmentally friendly. It utilizes the vacuum plasma process to enhance surface area and introduce functional groups onto the electrospun polymer nanofibers. Subsequent heat treatment results in the formation of activated multiporous carbon nanofibers. The type and density of the functional group introduced into the carbon structure were adjusted to the type of plasma gas (O2, NH3 and C4F8) being exposed. Among them, oxygen plasma-treated carbon nanofibers (O-MPCNFs) not only have a much larger active surface (517.84 m2 g−1) than other gases (290.62 m2 g−1 for NH3 and 159.29 m2 g−1 for C4F8), but also generate a lot of micropores, promoting rapid adsorption/desorption-inducted charges; therefore, they have excellent energy storage capacity. The O-MPCNF-based symmetrical two-electrode supercapacitor has a high specific capacitance (173.28 F g−1), rate capability and cycle stability (94.57% after 5000 cycles).

Fabrication of Multi-Layered Paper-Based Supercapacitor Anode by Growing Cu(OH)2 Nanorods on Oxygen Functional Groups-Rich Sponge-Like Carbon Fibers.

This work addresses the challenges in developing carbon fiber paper-based supercapacitors (SCs) with high energy density by focusing on the limited capacity of carbon fiber. To overcome this limitation, a sponge-like porous carbon fiber paper enriched with oxygen functional groups (OFGs) is prepared, and Cu(OH)2 nanorods are grown on its surface to construct the SC anode. This design results in a multi-layered carbon fiber paper-based electrode with a specific structure and enhanced capacitance. The Cu(OH)2 @PCFP anode exhibits an areal capacitance of 547.83 mF cm-2 at a current density of 1mA cm-2 and demonstrates excellent capacitance retention of 99.8% after 10 000 cycles. Theoretical calculations further confirm that the Cu(OH)2 /OFGs-graphite heterostructure exhibits higher conductivity, facilitating faster charge transfer. A solid-state SC is successfully assembled using Ketjen Black@PCFP as the cathode and KOH/PVA as the gel electrolyte. The resulting device exhibits an energy density of 0.21Wh cm-2 at 1.50mW cm-2 , surpassing the performance of reported Cu(OH)2 SCs. This approach, combining materials design with an understanding of underlying mechanisms, not only expands the range of electrode materials but also provides valuable insights for the development of high-capacity energy storage devices.

A comprehensive study of Bi2Sr2Co2Oy misfit layered oxide as a supercapacitor electrode material

Recently, the development of multiple functional energy storage materials having high energy storage capacity, expanded stability, and cost-effectiveness with eco-friendly nature is primary choice. Bi2Sr2Co2Oy (BSC-222) is misfit-layered oxide having significant thermoelectric (TE) capability with high temperature stability and eco-friendly characteristics. In present work, we successfully synthesized misfit layered BSC-222 oxide by using sol–gel method. X-ray diffraction, scanning electron microscopy, and atomic force microscopy are used to describe the structure and morphology of calcined BSC-222. Average thickness of prepared oxide sheets was found to be ∼30 to ∼40 nm. By using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 3 M KOH, the electrochemical analysis of produced BSC-222 electrodes was carried out. The CV and GCD analysis showed that the BSC-222 oxide having high secondary cobaltite phases has better charge storage capacity (166.6C × g−1) at 2 mVs−1 and majorly charge is stored through diffusion-controlled charge storage mechanism. A chemical reactions schematic is proposed for the charge storage mechanism. Moreover, this calcined BSC-222 exhibits better cycling stability of 68.8 % up to 5000 GCD cycles at 1.5 Ag−1 current density. Hence, BSC-222 misfit layered oxide demonstrates that it has capability to store charge with its good TE ability. This present work provides the first step towards utilizing good TE misfit layered materials even after some doping or modulation in their structure to fabricate high energy density energy storage devices with multifunctional characteristics.

Development and Characteristics Analysis of Novel Hydrated Salt Composite Adsorbents for Thermochemical Energy Storage

New composite adsorbents are proposed to further improve the application of thermochemical energy storage technology in buildings. A volcanic is taken as an adsorption substance, which is impregnated in 36.50 wt% and 54.00 wt% saturated MgCl2 and CaCl2 solutions to prepare composite adsorbents, which are called composite-MgCl2 and composite-CaCl2, respectively. According to the characterization, the main pore structure of the original volcanic is macropores (>100 nm), and hydrated salts tend to fill them. Compared with zeolite-MgCl2, the final water uptake of composite-MgCl2 and composite-CaCl2 increased by 0.15 g/g and 0.03 g/g. Meanwhile, the TG-DSC measurement results show that the thermochemical energy storage densities of composite-MgCl2 and composite-CaCl2 are 1.02 and 1.56 times that of zeolite-MgCl2, which are 642 kJ/kg and 983 kJ/kg, respectively. Moreover, the composition of the thermochemical energy storage densities of the composites is obtained by theoretical calculations, and the theoretically calculated results are close to the measured results. After several cycles, the composites still have high thermochemical energy storage capacity and low energy storage density cost.

Binder-free pinecone-like NiSe/MnSe nanostructure arrays via electrochemically controlled one-step synthesis towards high-performance semi-solid-state supercapacitor

Bimetallic selenides with nanostructures have attracted widespread interest to improve the electrochemical properties of supercapacitors due to their intrinsic properties such as high energy storage capacity, stability, and reliability. Herein, we report the novel synthesis of binder-free pinecone-like nanostructure arrays of Ni2MnSe4 on nickel foam via a facile electrodeposition technique. The electrode materials with various stoichiometric ratios of Ni:Mn as NixMn3-xSe4 (x = 1, 2, and 2.5) are synthesized to study the effect on their surface morphology and electrochemical properties. Ni2MnSe4 is optimized with pinecone-like structure arrays formed by intraconnected rough nanosheets (two-dimensional structure) with interconnected microstructures (pinecone structure), which further offers continuous channels for rapid electron/ion transfer and accelerates the diffusion kinetics of the counter ions, thus leading to improved capacitive property of the electrode material. The as-prepared Ni2MnSe4 electrode exhibits the areal capacitance value of 2160 mF cm−2 at 4 mA cm−2 with superior cycling stability (92 % of capacitance retention over 10,000 cycles). Additionally, the Ni2MnSe4 is utilized as a positive electrode for a semi-solid-state hybrid supercapacitor device (SHSC). The assembled SHSC delivers the energy and power density values of 0.15 mWh cm−2 and 15.51 mW cm−2, respectively with excellent prolonged cycling stability.

Numerical investigation of the melting characteristics of spherical-encapsulated phase change materials with composite metal fins

A spherical phase change material (PCM) capsule with embedded composite fins for latent thermal energy storage is proposed and studied in this paper. A three-dimensional numerical model is established and validated by comparing with experimental data in the literature. The influences of the embedded fins with different structures, capsule size, and heating temperature on the melting performance are analyzed. Results show that the insertion of composite metal fins promotes the melting process owing to the extension of thermal surface. The fin with perforations exhibits higher energy storage performance as compared to the non-perforated one, which can be attributed to the reduction of the blockage effect as well as the increment in the filling volume of PCM. The punched fin with three perforations in each sheet is preferable to adopting in spherical PCM capsule in view of the less time required for completely melting and the higher energy storage capacity. However, as the size of capsule increases, the heat transfer enhancement contributed by the inclusion of the embedded fins reduces. In addition, the melting process can be accelerated significantly by raising the temperature of external shell surface from 340 to 360 K, while such improvement tends to be less pronounced for the further increase in heating temperature. This study can provide useful guidance for the optimal design of thermal energy storage system with spherical PCM capsules.

Holey Graphene/Sulfur Composite Cathodes Via Coupling with Ferroelectric Nanoparticles for Sustainable and High-Capacity Lithium-Sulfur Batteries

Lithium-Sulfur (Li-S) batteries have been considered promising for high energy density batteries to be used in electronic devices, electric vehicles (EV) and aircrafts which are becoming more prevalent. In addition, Li-S batteries have high theoretical capacity of 1,675 mAh/g in comparison to LIBs of 300 mAh/g. Although Li-S batteries are in great demand, their development is still plagued by rapid capacity fading mainly stemming from polysulfide shuttle. To improve the electrochemical performance of the cathode in Li-S batteries, holey graphene (hG) and carbon-based materials are employed. Holey graphene (HG) contains conductive skeletons as electron transfer paths and abundant mesoporous for longitudinal transport of ions. This architecture ensures efficient charge delivery throughout a thick electrode and maximizes electrode utilization, achieving high-rate and high-capacity energy storage. The coupling of a highly polarized ferroelectric nanoparticles materials (FNPs) layer is an approach that can be used to reduce the characteristic polysulfide shuttling in Li-S batteries. This coupling helps to build up an internal electric field and induces macroscopic charge separations on the surface of the cathode of Li-S batteries. The dry compression manufacturing process facilitates bonding between Sulfur and ferroelectric nanoparticles to generate a more stable cathode. In the present report we are presenting preliminary results of cathode having composition S47.5(FNPs)5hG47.5 in terms of structure, surface morphology and electrochemical performance. A reversible capacity of ~1,400 mAh/gs has been achieved with high coulombic efficiencies (> 87%) and low-capacity fading rate of 0.016% per cycle upto 60 cycles. The active sulfur mass loading ranging from 5.72 mgs/cm2 to 7.01 mgs/cm2 allows maximum high areal capacity up to ~10 mAh/cm2 and superior rate capability for 0.2mA/cm2 and 0.5 mA/cm2. These results suggest sustainable and high-yielding Li–S batteries can be obtained for potential commercial applications.

Ultra-thick, dense dual-encapsulated Sb anode architecture with conductively elastic networks promises potassium-ion batteries with high areal and volumetric capacities

Ultra-thick, dense alloy-type anodes are promising for achieving large areal and volumetric performance in potassium-ion batteries (PIBs), but severe volume expansion as well as sluggish ion and electron diffusion kinetics heavily impede their widespread application. Herein, we design highly dense (3.1 ​g ​cm−3) Ti3C2Tx MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti3C2Tx-G) with high-conductivity elastic networks (1560 ​S ​m−1) and compact dually encapsulated structures, which exhibit a large volumetric capacity of 1780.2 ​mAh cm−3 (gravimetric capacity: 565.0 ​mAh g−1), a long-term stable lifespan of 500 cycles with 82% retention, and a large areal capacity of 8.6 ​mAh cm−2 (loading: 31 ​mg ​cm−2) in PIBs. Using ex-situ SEM, in-situ TEM, kinetic investigations, and theoretical calculations, we reveal that the excellent areal and volumetric performance mechanism stems from the three dimensional (3D) high-conductivity elastic networks and the dual-encapsulated Sb architecture of Ti3C2Tx and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti3C2Tx also decreases the K+ diffusion energy barrier, and the ultra-thick compact electrode ensures volumetric and areal performance. These findings provide a feasible strategy for fabricating ultra-thick, dense alloy-type electrodes to achieve high areal and volumetric capacity energy storage via highly-dense, dual-encapsulated architectures with conductive elastic networks.

Augmenting electrochemical performance of nickel-rich NMC for lithium-ion batteries by combining material synthesis modification and redistribution of transition metal ion concentration

Modification of synthesis approach and material surface are well known to be elegant straightforward routes to augment the electrochemical performance of cathode materials for lithium-ion batteries. In this study, we combined the co-precipitation method modification and surface modification of material by redistributing the transitions metal ions content to synthesis nickel-rich NMC (Li1.0Ni0.8Mn0.1Co0.1O2, NMC811 M). The pristine NMC811, and NMC811 M both exhibit high energy storage capacity with initial discharge specific capacity up to approximately 220 mAh g−1 at a current density of 10 mA g−1. The achieved results also indicate that, the NMC811 M with transition metal ion content redistribution is of better capacity retention than the pristine NMC811, it maintains approximately 73% of its original capacity after 100 cycles corresponding to a specific capacity of 153 mAh g−1. This work provides a simple but effective approach dedicated to significantly enhancing the electrochemical performance of nickel-rich NMC, and thus paves a way towards high performance battery electrodes.

Carbon-cement supercapacitors as a scalable bulk energy storage solution.

The large-scale implementation of renewable energy systems necessitates the development of energy storage solutions to effectively manage imbalances between energy supply and demand. Herein, we investigate such a scalable material solution for energy storage in supercapacitors constructed from readily available material precursors that can be locally sourced from virtually anywhere on the planet, namely cement, water, and carbon black. We characterize our carbon-cement electrodes by combining correlative EDS-Raman spectroscopy with capacitance measurements derived from cyclic voltammetry and galvanostatic charge-discharge experiments using integer and fractional derivatives to correct for rate and current intensity effects. Texture analysis reveals that the hydration reactions of cement in the presence of carbon generate a fractal-like electron-conducting carbon network that permeates the load-bearing cement-based matrix. The energy storage capacity of this space-filling carbon black network of the high specific surface area accessible to charge storage is shown to be an intensive quantity, whereas the high-rate capability of the carbon-cement electrodes exhibits self-similarity due to the hydration porosity available for charge transport. This intensive and self-similar nature of energy storage and rate capability represents an opportunity for mass scaling from electrode to structural scales. The availability, versatility, and scalability of these carbon-cement supercapacitors opens a horizon for the design of multifunctional structures that leverage high energy storage capacity, high-rate charge/discharge capabilities, and structural strength for sustainable residential and industrial applications ranging from energy autarkic shelters and self-charging roads for electric vehicles, to intermittent energy storage for wind turbines and tidal power stations.

Homogeneous Li deposition guided by ultra-thin lithiophilic layer for highly stable anode-free batteries

Li-metal batteries (LMBs) are intensively studied to keep up with the growing demand for sustainable and high-capacity energy storage devices. However, the practical implementation of LMBs is still challenging owing to the catastrophic side effects associated with the growth of dendritic Li and inferior Coulombic efficiency. To enhance the long-term electrochemical stability and high-rate performance of LMBs, it is crucial to control the morphology of Li deposition over the current collectors. Herein, we propose surface-modified current collectors to investigate how a lithiatable layer affects the morphology of Li deposition and thus contributes to the stable electrochemical performance of LMBs at high current densities. The lithiatable layer improves the electrolyte wetting ability, which efficiently diminishes the interfacial resistance between electrode and electrolyte. Moreover, the lithiatable layer induces homogeneous Li nucleation, consequently leading to the uniform Li deposition over the surface of current collectors. Due to these synergistic effects, the anode-free cells with surface-modified current collectors have achieved excellent cycle stability in comparison to that with conventional Cu current collector.

High Mechanical Energy Storage Capacity of Ultranarrow Carbon Nanowires Bundles by Machine Learning Driving Predictions

Energy storage and renewable energy sources are critical for addressing the growing global energy demand and reducing the negative environmental impacts of fossil fuels. Carbon nanomaterials are extensively explored as high reliable, reusable, and high‐density mechanical energy storage materials. In this context, machine learning techniques, specifically machine learning potentials (MLPs), are employed to explore the elastic properties of 1D carbon nanowires (CNWs) as a promising candidate for mechanical energy storage applications. The study focuses on the elastic energy storage properties of these CNWs, utilizing MLPs trained with data from first‐principles molecular dynamics simulations. It is found that these materials exhibit an exceptionally high tensile elastic energy storage capacity, with a maximum storage density ranging from 2262 to 2680 kJ kg−1. Furthermore, it is discovered that some CNWs exhibit a superior torsional energy storage capacity compared to their tensile energy storage capacity. Overall, this research demonstrates the effectiveness of machine learning‐based computational approaches in accelerating the exploration and optimization of novel materials. It also highlights the potential of CNWs as promising candidates for future energy storage applications.

The sono-PCM reactors: A new approach for recovering the heat dissipated from ultrasonic reactors using a phase change material

To keep sonochemical reactors at a constant temperature, cryothermostat systems (equipped with a pump, cooling fluids and tubing) are commonly used. The cryothermostat serves a dual purpose, supplying both heating and cooling as needed to keep the temperature stable. However, this device is an energy consumer, especially when the sonochemical reaction is carried out over an extended period of time (hours to days). As a result, alternative systems are required to reduce the operating cost of sonosystems. The present work introduces a new approach of incorporating phase change materials (PCMs) for the recovery and storage of heat dissipated from ultrasonic reactors (i.e. the sono-PCM reactor approach). The purpose of the project is to go as far as replacing the circulating fluid-based cooling system with a small PCM unit capable of absorbing the generated heat flux and storing it in the form of latent heat (with phase change). The analysis was made on sonicated water (300 mL) in a standing wave ultrasonic reactor operating at 300 kHz, where the dissipated heat flux was measured calorimetrically. After that, using a computational fluid dynamics (CFD) model (implemented in ANSYS Fluent® software), the energetic performance of the PCM unit was assessed by tracking the system (i.e. the sono-PCM reactor) response (i.e. average and spatial evolutions of temperature, enthalpy, total energy, velocity and PCM-melting kinetics) to the imposed acoustic energy. Paraffin RT31 was selected as PCM because of its suitable characteristics such as low melting point (27–31 °C) and high thermal energy storage capacity (165 kJ kg−1). Despite the relatively low thermal conductivity of the used PCM (0.2 W m− 1 °C − 1), promising results have been obtained in terms of thermal energy management and storage using a phase change material (PCM) instead of a water-cooling system.

Experimental study on thermal performance of ultra-thin heat pipe with a novel composite wick structure

The rapid advancement of high-performance electronic devices and high-capacity energy storage has prompted the development of ultra-thin heat pipes with a higher heat transfer limit, faster start-up speed, and lower thermal resistance. In the present study, a novel double-layer wick structure comprising sintered copper powder and spiral woven mesh was proposed to analyze how various combinations of porous media properties, structures, and heating surfaces influence the thermal performance of ultra-thin heat pipes. The wick structure consists of two layers: a layer of sintered copper powder with four different particle sizes and a layer of spiral woven mesh. To improve the starting characteristics, the starting time under different thermal loads was studied. Additionally, a comparison study was conducted between the ultra-thin heat pipe with a single type wick structure and the proposed wick structure. The results revealed that the ultimate power in the two horizontal states was 50 W. The thermal resistance of Horizontal-1 (heat applied to the sintered copper powder side) was 0.069 W/°C, and for Horizontal-2 (heat applied to the spiral woven mesh side), it was 0.093 W/°C, both measured at their respective ultimate thermal loads. Additionally, among all four structures in Horizontal-1, the shortest start-up time occurred at a power of 30 W, with a duration of 42 s. Finally, when compared to the single wick structure, the proposed double-layer wick structure exhibited an 11.1% increase in ultimate power.

Introducing non-conjugated ionic spacer in metallo-supramolecular polymer: Generation of nanofibers for high-performance electrochromic supercapacitor

The use of indicative electrochromic (EC) supercapatteries is gaining significant attention for their ability to indicate their charging and discharging status through optical color changes and their high energy and power densities, making them a promising renewable alternative energy source. In this study, we performed molecular engineering to prepare a non-conjugated pyridinium cation-containing bisterpyridine ligand (TpyNTpy) and its metallo-supramolecular polymer (MSP), Fe-TpyNTpy. The MSP was thoroughly characterized through spectroscopic, morphological, and structural studies, revealing a homogeneous nanofiber morphology with good thermal stability. The gel-state EC devices, fabricated using Fe-TpyNTpy as the active layer, demonstrated EC color changes from purple to dirty white, with a large optical contrast of 47% at 570 nm, fast coloration (1.5 s) and bleaching (2.4 s) times, high coloration efficiency of 312.8 cm2C-1, longer optical memory, and extremely high EC cycle stability. Incorporating nonconjugated and ionic ligands helped address the opposite electrochemical behaviors, such as EC fastness and optical memory. The Fe-TpyNTpy film showed good supercapacitive properties in solution electrolytes, and the energy storage behavior was correlated with EC transmittance/color change. The energy storage properties were evaluated by preparing a hybrid ESD. The Fe-TpyNTpy and Prussian blue containing hybrid ESD exhibited an improved volumetric capacitance of 73 ± 2F/cm3 with low iR drop, high energy storage capacity (energy density 61 mWh/cm3 at a power density of 8.5 W/cm3), and 95% retention of initial volumetric capacitance after 10,000 charge–discharge cycles. The hybrid ESD can illuminate a single LED, demonstrating the practical applicability of the ESD.