Light Energy Storage Research Articles

Preparation and properties of polyurethane film with photothermal conversion and energy storage capability

Purpose This paper aims to provide a flexible polyurethane (PU) film with visible light trapping ability, photothermal conversion and energy storage performance by covalently bonded a visible light absorbing dye into the polymer through copolymerization. Design/methodology/approach For this target solution copolymerization of diphenyl-methane-diisocyanate (MDI), poly(1,4-butylene adipate) (PBA2000), polyethylene glycol (PEG) of different molecular weight, self-made dye, 1,4-butanediol (BuOH) was carried out in a flame-dried flask under an inert nitrogen (N2) atmosphere. First, an isocyanate-terminated prepolymer of dried PEG, MDI and PBA2000 was prepared in dimethylformamide and stirred for 1 h at 35°C. Then, self-made dye and 1, 4-butanediol (BuOH) were added and heated at 85°C for 3 h to get photothermal conversion polyurethane (PTPU) solution. Allowed the solution to dry at room temperature for seven days and then at 65°C for 12 h to get PTPU films. Findings The flexible PU films with photothermal conversion and energy storage performances were successfully synthesized and the functional films presented both excellent energy storage and mechanical property when the molecular weight of PEG was in the range of 6,000∼10,000. Research limitations/implications The materials that were used in this research paper had a reasonably low cost. Also, the procedures for the synthesis of dye and polymers were extremely easy because there was no need for high pressure or temperature and no dangerous solvents were used. Practical implications The photothermal conversion property and mechanical performance of the synthesized flexible PU films were characterized. The results have proved that these films were soft and elastic, and have certain photothermal conversion and energy storage ability, thus can be used in the surface finishing of special fabric and leather. Originality/value Visible light trapping photothermal conversion PU flexible film with energy storage capability was prepared for the first time.

Review on Comparison of Different Energy Storage Technologies Used in Micro-Energy Harvesting, WSNs, Low-Cost Microelectronic Devices: Challenges and Recommendations

This paper reviews energy storage systems, in general, and for specific applications in low-cost micro-energy harvesting (MEH) systems, low-cost microelectronic devices, and wireless sensor networks (WSNs). With the development of electronic gadgets, low-cost microelectronic devices and WSNs, the need for an efficient, light and reliable energy storage device is increased. The current energy storage systems (ESS) have the disadvantages of self-discharging, energy density, life cycles, and cost. The ambient energy resources are the best option as an energy source, but the main challenge in harvesting energy from ambient sources is the instability of the source of energy. Due to the explosion of lithium batteries in many cases, and the pros associated with them, the design of an efficient device, which is more reliable and efficient than conventional batteries, is important. This review paper focused on the issues of the reliability and performance of electrical ESS, and, especially, discussed the technical challenges and suggested solutions for ESS (batteries, supercapacitors, and for a hybrid combination of supercapacitors and batteries) in detail. Nowadays, the main market of batteries is WSNs, but in the last decade, the world’s attention has turned toward supercapacitors as a good alternative of batteries. The main advantages of supercapacitors are their light weight, volume, greater life cycle, turbo charging/discharging, high energy density and power density, low cost, easy maintenance, and no pollution. This study reviews supercapacitors as a better alternative of batteries in low-cost electronic devices, WSNs, and MEH systems.

Electrical and Capacitive Response of Hydrogel Solid-Like Electrolytes for Supercapacitors.

Flexible hydrogels are attracting significant interest as solid-like electrolytes for energy storage devices, especially for supercapacitors, because of their lightweight and anti-deformation features. Here, we present a comparative study of four ionic conductive hydrogels derived from biopolymers and doped with 0.1 M NaCl. More specifically, such hydrogels are constituted by κ-carrageenan (κC), carboxymethyl cellulose (CMC), poly-γ-glutamic acid (PGGA) or a phenylalanine-containing polyesteramide (PEA). After examining the morphology and the swelling ratio of the four hydrogels, which varies between 483% and 2356%, their electrical and capacitive behaviors were examined using electrochemical impedance spectroscopy. Measurements were conducted on devices where a hydrogel film was sandwiched between two identical poly(3,4-ethylenedioxythiophene) electrodes. The bulk conductivity of the prepared doped hydrogels is 76, 48, 36 and 34 mS/cm for PEA, PGGA, κC and CMC, respectively. Overall, the polyesteramide hydrogel exhibits the most adequate properties (i.e., low electrical resistance and high capacitance) to be used as semi-solid electrolyte for supercapacitors, which has been attributed to its distinctive structure based on the homogeneous and abundant distribution of both micro- and nanopores. Indeed, the morphology of the polyestermide hydrogel reduces the hydrogel resistance, enhances the transport of ions, and results in a better interfacial contact between the electrodes and solid electrolyte. The correlation between the supercapacitor performance and the hydrogel porous morphology is presented as an important design feature for the next generation of light and flexible energy storage devices for wearable electronics.

Layer-by-Layer Assembly of Reduced Graphene Oxide and MXene Nanosheets for Wire-Shaped Flexible Supercapacitors.

As the demand for wearable electronic devices increases, interest in small, light, and deformable energy storage devices follows suit. Among these devices, wire-shaped supercapacitors (WSCs) are considered key components of wearable technology due to their geometric similarity to woven fiber. One potential method for creating WSC devices is the layer-by-layer (LbL) assembly technique, which is a "bottom-up" method for electrode fabrication. WSCs require conformal and adhesive coatings of the functional material to the wire-shaped substrate, which is difficult to obtain with other processing techniques such as vacuum filtration or spray-coating. However, the LbL assembly technique produces conformal and robust coatings that can be deposited onto a variety of substrates and shapes, including wires. In this study, we report WSCs made using the LbL assembly of alternating layers of positively charged reduced graphene oxide functionalized with poly(diallyldimethylammonium chloride) and negatively charged Ti3C2Tx MXene nanosheets conformally deposited on activated carbon yarns. In this construct, the added LbL film enhances capacitance, energy density, and power density by 240, 227, and 109%, respectively, relative to the uncoated activated carbon yarn, yielding high specific and volumetric capacitances (237 F g-1, 2193 F cm-3). In addition, the WSC possesses good mechanical stability, retaining 90% of its initial capacity after 200 bending cycles. This study demonstrates that LbL coatings on carbon yarns are promising as linear energy storage devices for fibrous electronics.

Palm oil mill effluent treatment using tungsten trioxide: Adsorption and photocatalytic degradation

Abstract Today, some of the major disadvantages of conventional palm oil mill effluent (POME) treatment are that the process is time consuming, as well as space consuming. Besides, most of the recent photocatalyst still have a limitation that able to demonstrate their good performances only under sources of light. The visible-light-driven energy storage photocatalyst, which is tungsten trioxide (WO3), has been developed to overcome the limitations mentioned. Therefore, the present study aims to investigate the comparative calcination temperature and the degradation of POME using WO3 as a photocatalyst in adsorption and photocatalytic processes under visible light irradiation. An eco-friendly WO3 photocatalyst was synthesized by coprecipitation method. Subsequently, the resulting WO3 was characterized by Fourier-transform infrared spectroscopy (FTIR) to evaluate the significance of calcination temperature towards WO3. Furthermore, the adsorption activity of WO3 towards POME was investigated at different sources of ponds (cooling, anaerobic and aeration) throughout 300 min. This study reports on the efficiency of adsorption activity of WO3-400 °C towards pond aeration pollution, which showed that it was better than that in anaerobic and cooling ponds based on the chosen study criteria of color and suspended solid removal for the investigation of photocatalytic activity. Moreover, WO3 was proven to be able to conserve energy, where it was demonstrated that POME can still degrade consistently in darkness, with the highest color removal of approximately 48% was obtained. An extraordinary photocatalytic treatment with WO3 functioning simultaneously as the light harvesting and energy storage material is deemed as an efficient photocatalyst for POME in terms of decolorization and removal of suspended solid.

Hybrid Turbo Compound Fan Engine an Eco-Efficient Propulsion System for Aviation

The path to electric propulsion systems depends on the development of powerful, compact and very light energy storage system with a high storage density. In order to create an environment-friendly intermediate solution in the medium term, especially for aircraft engines of medium power classes, it makes sense to use an innovative, electrically parallel hybrid unit based on rotary engines and electric boosters for start and climb phases as a propulsion system. An aero-engine application, based on the HSD concept (HSD = hybrid super-drive – hybrid Wankel rotary engine) for different hybrid-parallel propulsion systems is presented. In this article, the introduced technology is based on a currently produced family of multi-component Wankel rotary engines. The proposed HSD concept uses a chamber volume of 650ccm per rotor. The projected power range (0.8 to 1.36 MW) is covered by an innovative hybrid electric parallel turbo compound concept together with 2x4 rotary engine units. A novel, air-bearing turbo engine with integrated electric drive is used as a turbocharger for charging the rotary engine. For the aero-engine technology, the counter-rotating fan (CRF) concept shown as an example for an aircraft technology carrier (light jet) leads to a further increase in the efficiency of a complete system.

Investigation of germanium selenide electrodes for the integrated photo‐rechargeable battery

Autonomous photo-rechargeable electronic energy storage device has become a new type of solution to the problems of renewable energy fluctuations and storage. The combination of light conversion equipment and energy storage equipment improves the packaging efficiency of the equipment, however how to explore a type of electrode materials for energy collection and storage become a real challenging issue. Here, we try to explore the GeSe nanoparticles as the potential idea electrode for the integrated photo-rechargeable battery. On the one hand, GeSe nanoparticle electrode shows good Li+ storage performances. At the current density of 0.2 A g−1, its reversible capacity is 670 mAh g−1 after 100 cycles. On the other hand, during the photo-voltaic measurement, GeSe electrodes could generate a photocurrent that increases by 8 uA/cm2 under the visible light irradiation in aqueous electrolyte. When LiClO4 in polycarbonate solvent is used as the electrolyte, the electrons move in the reverse direction from the GeSe electrode, form reverse current, reduce Li+ to lithium metal, and finally store light energy into chemical energy in a short time. Considering its presenting behaviors in Li+ storage and photon harvesting, our research proposed the possibility for the application of GeSe materials in the integrated photo-rechargeable batteries.

Photoactivated Artificial Molecular Machines that Can Perform Tasks.

Research on artificial photoactivated molecular machines has moved in recent years from a basic scientific endeavor toward a more applicative effort. Nowadays, the prospect of reproducing the operation of natural nanomachines with artificial counterparts is no longer a dream but a concrete possibility. The progress toward the construction of molecular-machine-based devices and materials in which light irradiation results in the execution of a task as a result of nanoscale movements is illustrated here. After a brief description of a few basic types of photoactivated molecular machines, significant examples of their exploitation to perform predetermined functions are presented. These include switchable catalysts, nanoactuators that interact with cellular membranes, transporters of small molecular cargos, and active joints capable of mechanically coupling molecular-scale movements. Investigations aimed at harnessing the collective operation of a multitude of molecular machines organized in arrays to perform tasks at the microscale and macroscale in hard and soft materials are also reviewed. Surfaces, gels, liquid crystals, polymers, and self-assembled nanostructures are described wherein the nanoscale movement of embedded molecular machines is amplified, allowing the realization of muscle-like actuators, microfluidic devices, and polymeric materials for light energy transduction and storage.

Polyethylene glycol based self-luminous phase change materials for both thermal and light energy storage

Except for the improvement enthalpy value and thermal conductivity of conventional solid-solid phase change materials (SSPCMs), expansion of additional functions other than thermal energy storage function of that has been particularly attractive. In this work, a novel self-luminous SSPCMs based polyethylene glycol have been successfully synthesized via incorporation of long afterglow luminescence (LAL) particles into SSPCMs in the absence of any isocyanates and solvents. The prepared self-luminous SSPCMs have high melting latent heats with a maximum value at 120.2 J g−1, maximum encapsulation ratio of 80.6%, and a suitable phase change temperature around 28 °C. Importantly, the prepared self-luminous SSPCMs with different concentrations of LAL particles can absorb and store visible light sources in the daylight but can slowly release blue light in the dark over a long time. Furthermore, the prepared self-luminous SSPCMs after thermal cycling tests and storing-releasing light energy cycling tests have preeminent thermal reliability, luminescence repeatability and chemical structure reliability for a long time practical application.

Optimizing Light Storage in Scattering Media with the Dwell-Time Operator

We prove that optimal control of light energy storage in disordered media can be reached by wave front shaping. For this purpose, we build an operator for dwell times from the scattering matrix and characterize its full eigenvalue distribution both numerically and analytically in the diffusive regime, where the thickness L of the medium is much larger than the mean free path ℓ. We show that the distribution has a finite support with a maximal dwell time larger than the most likely value by a factor (L/ℓ)^{2}≫1. This reveals that the highest dwell-time eigenstates deposit more energy than the open channels of the medium. Finally, we show that the dwell-time operator can be used to store energy in resonant targets buried in complex media, without any need for guide stars.

An Intrinsic Photothermal Liquid for Light Detection and Energy Storage.

Photothermal materials (PTMs) have been intensively investigated in the fields of photothermal conversion. Superior to solid PTMs, liquid PTMs are leading the trends in satisfying the demands of high flexibility and easy recycling. Successful examples of liquid PTMs are mostly formulated by dispersing solid PTMs in solvents, but suffer from the problems of phase segregation and solvent pollution. In this work, a low-cost formulation is proposed, which involves an oxidative product of ethyl oleate by iodine. It is an intrinsic liquid PTM, preserving the fluidic nature as well as possessing considerable ability for photothermal conversion. In addition to understanding the mechanism of light absorption in the visible and even near infrared windows, two examples are presented to demonstrate the great potential of liquid PTMs in broad areas such as light sensing and energy storage.

Improved energy density and charge-discharge efficiency in solution processed highly defined ferroelectric block copolymer-based dielectric nanocomposites

The development of light and flexible capacitive energy storage devices with high electrical energy densities is of crucial significance to respond to the ever-rising demands in advanced applications and electricity needs. Incorporation of high dielectric constant ceramic fillers inside the ferroelectric polymer matrix offers great potential to improve the energy density of dielectric materials. However, this approach often suffers from highly reduced breakdown strength caused by the large difference of the matrix and filler dielectric constants together with often poor dispersion of the ceramic additives inside the polymer. Here, we demonstrate a simple method for the preparation of improved polymer-based dielectric nanocomposites based on self-assembly of medium dielectric constant hafnium oxide nanorods using ferroelectric block copolymer. The prepared nanocomposites exhibit both improved discharged energy densities and charge-discharge efficiencies, whereas they preserve their function up to comparable electric fields as the pristine block copolymer. The enhancement of the properties is mostly ascribed to the formation of deeper charge traps due to nanorod induced crosslinking inside amorphous domains and the reduction of ferroelectric loss influenced by creation of an additional paraelectric phase in nanocomposites.

Flexible phase change composite materials with simultaneous light energy storage and light-actuated shape memory capability

Phase change materials (PCMs) are widely used in the thermal energy storage fields. However, the strong rigidity and poor photoabsorption ability of PCMs have inhibited their advanced applications. In this work, the flexible and light-responsive PCM composites consisting of paraffin and olefin block copolymer (OBC) filled with carbon nanotubes (CNTs) were prepared. The paraffin/OBC blend with appropriate ratio (60/40 wt%) not only has good encapsulation ability and high latent heat (111.7 J/g), but also shows thermal-actuated shape memory effect by triggering the phase transition of paraffin. Furthermore, by adding a small amount of CNTs, the paraffin/OBC/CNT composites exhibit simultaneous light-to-thermal energy storage and light-actuated shape memory capability. A light-responsive and temperature-controlled actuator is further exploited, which is beneficial for the installation and thermal management of devices with limited space. Considering the easy processing and inexpensive sources, the flexible and light-responsive PCM composites have great prospect in advanced light energy storage systems.

Graphene for Energy Storage and Conversion: Synthesis and Interdisciplinary Applications

2D graphene materials possess excellent electrical conductivity and an sp2 carbon atom structure and can be applied in light and electric energy storage and conversion applications. However, traditional methods of graphene preparation cannot keep pace with real-time synthesis, and therefore, novel graphene synthesis approaches have attracted increasing attention from researchers to accurately control graphene structure and morphology. Based on this, this review will discuss the novel synthesis of graphene for interdisciplinary applications of energy storage and conversion, which is a promising direction in the research for novel applications in photoelectrochemical cells, photo-assisted batteries, piezoelectric nanogenerators, photothermal and photomechanical devices, etc.

Self-luminous wood composite for both thermal and light energy storage

High efficient energy storage devices for both thermal energy and light energy are scarce in the development of modern society to reduce energy consumption. In this work, a novel self-luminous wood composite based on phase change materials (PCMs) with superior thermal energy storage and long afterglow luminescence (LAL) materials with excellent light energy storage is reported. The obtained self-luminous wood composites shows high latent heat of fusion (146.7 J g-1), suitable phase change temperature at about 37 ℃, favorable thermal reliability and thermal stability below 105 ℃ with excellent shape-stability. More importantly, the self-luminous wood composites can absorb ultraviolet and visible light from lighting source and natural light, and emit green light in the dark for 11 h. More interesting, the addition of LAL particles can improve the thermal conductivity of self-luminous wood composites. All results demonstrate self-luminous wood composites can store both thermal energy and light energy, and have great potential in applications including furniture, emergency light, storage and building energy conservation.

α-Fe2O3 thin film on stainless steel mesh: A flexible electrode for supercapacitor

Abstract Light and flexible energy storage devices have taken great attention from the industrial point of view. We report for the first time the deposition of α-Fe 2 O 3 on thin, light weight and flexible stainless steel mesh substrate. Liquid phase deposition (LPD) which is simple, inexpensive and additive/binder free method is used for deposition. Supercapacitive performance of α-Fe 2 O 3 thin films deposited on stainless steel mesh are studied in 0.5 M Na 2 SO 3 electrolyte. The highest specific capacitance obtained is 960 F g −1 at 4 mA cm −2 from charge-discharge curves. The supercapacitive performance is significantly improved when α-Fe 2 O 3 thin films are deposited on mesh substrate as compared to flat substrate.

Flexible Asymmetric Microsupercapacitors from Freestanding Hollow Nickel Microfiber Electrodes

AbstractThe increasing demand for flexible and wearable microelectronics is a major driving force for the development of high‐performance small‐volume energy sources. Microsupercapacitors exhibit significant potential in energy storage as they provide high power and good cycle stability. Yet, most microsupercapacitors display low energy densities limiting their practical use in microelectronics. Here, synthesis of high surface area freestanding electrodes comprising hollow nickel microfibers is demonstrated. The microfiber nickel electrodes constitute a platform for flexible asymmetric microsupercapacitors exhibiting excellent mechanical resilience as well as high energy density (0.11 mWh cm−2) and power density (37.5 mW cm−2). The freestanding nature and extensive surface area of the electrodes contribute to pronounced areal and volumetric capacitance, energy storage values, and stability after numerous (hundreds) physical bending cycles. The simple preparation scheme and use of an inexpensive building block (e.g., nickel) underscore potential uses as light and flexible energy storage devices.

Quantum dots for light conversion, therapeutic and energy storage applications

In this review paper, we highlight the utilization of nanostructured quantum dots (QDs) in light-emitting diodes, biomedical, and energy-related applications. We discuss different preparation methods, cation-doping effects, and the optical applications of perovskite QDs. Cadmium selenide QDs are semiconductor materials with narrow bandgaps; therefore, their optical properties and electronic structures can be tuned. They can absorb photons (light energy) and convert multiple electron-hole pairs efficiently via multiple exciton generations. These effective light absorption properties are suitable for solar-driven water electrolysis processes and efficient photo-electrochemical lithium-air batteries. We focus on the utilization of upconverting nanoparticles in the field of biomedical applications. Suitable bandgap position, efficient charge separation, transportation, and photo-stability are the advantages of QD nanostructured materials. Hence, they are efficient and challenging candidates for the future.

Aerosol assisted chemical vapor deposition (AACVD) synthesis of nanostructured cauliflower patterning in MWCNT doped tungsten oxide

We report nanostructured tungsten oxide (WO) cauliflowers for the first time that are fabricated onto silica glass substrate at 400 °C by aerosol assisted chemical vapor deposition using tungsten hexacarbonyl and multiwalled CNTs in toluene. The deposited films are characterized by Scanning electron microscopy, Energy dispersive x-ray spectroscopy, X-ray diffractometry, Fourier transform infrared and UV–VIS spectroscopy and four-point probe for microstructural, optical and electrical properties. Surface morphology exhibits the growth of nanocauliflowers followed by the aggregation of spherical nanoparticles with high angle grain boundaries. Structural information reveals the transformation of triclinic to tetragonal phase with preferential switching from (0 2 0) to (0 0 1) plane having signatures of W-O-W symmetric vibration between (700cm-1 and 900 cm−1, somewhat perturbed by the addition of doping. In additions, films show inconsistent variation in electrical resistivity (15–109) Ω-cm due to agglomeration of MWCNTs at grain boundaries and appearance of “nanocracks” due to ionic radii mismatch of tungsten and CNTs at higher doping ratios. Black color films present decrease in optical transmittance for range of 300–400 nm attributed to trapping sites and defects generated due to incorporation of multiwalled CNTs. The splitting of Fermi level as a result of incorporation of MWCNTs caused the increase of band gap energy in range of 3.18 eV, useful in tungsten oxide based new material system which can act as the light harvesting material and energy storage simultaneously.

Facile morphology control of high aspect ratio patterned Si nanowires by metal-assisted chemical etching

Facile and effective method to fabricate highly ordered silicon nanowires (SiNWs) using metal-assisted chemical etching (MACE) was demonstrated. MACE solutions with various concentrations were studied to understand the etching mechanism for patterned Si substrates with different doping concentrations. MACE rate of Si (100) at different time periods was studied with different doping concentrations (p, p+, n, and n+) at a MACE solution concentration of 5:1:1 for an accurate morphology control and reproducibility of the SiNWs. Based on a four-step model, the SiNW formation mechanism was proposed involving anisotropic etching of SiNWs based on hole transfer between Au/Si interfaces exposed when subjected to MACE solution. Time dependent variation in etch rate of Si to fabricate SiNWs was observed with different doping concentration. The effect of the doping concentration on the etching was revealed based on band diagrams. However, agglomeration of p+-SiNWs was observed, which was attributed to their doping and ability to act against various forces like surface tension during drying. Different aspect ratios of SiNWs were observed for different time periods; n+-SiNWs exhibited the maximum aspect ratio of approximately 81. A visible-light absorbance analysis revealed the potential of the synthesized SiNWs can be good base and host materials for various light harvesting and energy storage devices.