Energy Harvesting Devices Research Articles

Exploring novel Zr2GeX (X = C, N, F) MAX phases by first-principles approach

In recent years, there has been a surge of interest in the thermodynamically stable nanolaminate ternary carbides/nitrides known as MAX phases. In this first-principles research work, we focus on the MAX phases with a particular emphasis on Zr2GeX (X = C, N, F) compounds. These novel Zr2GeX compounds exhibited considerable values of cohesive energy, demonstrating stability comparable to well-established MAX compounds. Our calculations for the structural parameters of Zr2GeX agree well with the literature, indicating the reliability of our results. The absorption coefficients for ultraviolet (UV) light are approximately 105/cm and 106/cm, respectively, highlighting their significance for energy harvesting devices. Additionally, these metallic compounds demonstrate impressive reflectivity, reflecting over 50% of infrared and visible light. Similarly, they exhibit the highest refraction for infrared light, with a significant decrease in refraction for visible and UV light. Consequently, the transparency of Zr2GeX compounds diminishes, rendering them opaque against UV light and highly likely to absorb most incident UV radiation. Results presented in this paper highlight the potential applications of Zr2GeX MAX phases for optoelectronic devices due to their exceptional electronic and optical properties.

Integrated device for multiscale series vibration reduction and energy harvesting

A multi-degree-of-freedom device is proposed, which can achieve efficient vibration reduction as the main objective and energy harvesting as the secondary purpose. The device comprises a multiscale nonlinear vibration absorber (NVA) and piezoelectric components. Energy conversion and energy measurement methods are used to evaluate the device performance from multiple perspectives. Research has shown that this device can efficiently transfer transient energy from the main structure and convert a portion of transient energy into electrical energy. Main resonance and higher-order resonance are the main reasons for efficient energy transfer. The device can maintain high vibration reduction performance even when the excitation amplitude changes over a large range. Compared with the single structures with and without precompression, the multiscale NVA-piezoelectric device offers significant vibration reduction advantages. In addition, there are significant differences in the parameter settings of the two substructures for vibration reduction and energy harvesting.

A comparative analysis of flexible pvdf based smart films for advanced electromagnetic shielding applications using a machine learning approach

Due to emerging technology, the usage of electronic gadgets has paved a route for the arousal of Electromagnetic Interference (EMI) pollution. Electromagnetic pollution is considered a global threat that can harm all biological systems and technological equipment. To overcome this issue, a suitable shielding material has to be implemented to attenuate the incoming electromagnetic waves. On the other hand, compared to traditional materials, recently, polymers have grabbed excellent responses in various fields of material science and modern chemistry. Specifically, functional polymers are increasing their scope in industry and academia due to their unique features, such as magnetic, catalysis, optical and piezoelectric properties. In this regard, Polyvinylidene Fluoride (PVDF), a well-known semicrystalline polymer from the family of Fluoropolymers, has achieved remarkable in various applications of sensors, actuators, biomedical scaffolds and energy harvesting devices. PVDF has also contributed excellent outcomes as a shielding material as they are transparent to light and flexible. Hence, this research work attempts to fabricate PVDF thin films with various weight percentages of nanofillers such as Zinc oxide (ZnO), Zirconium oxide (ZrO2), and Titanium dioxide (TiO2). Further, all the samples were tested for electromagnetic shielding effectiveness (SE). Further, these experimental results were compared with statistical and computational approaches such as the Gradient Descent Algorithm (GDA) and Response Surface Methodology (RSM). Based on the experimental results, it was observed that the PVDF nanofilm fabricated with 0.3 wt% of ZrO2, 0.5 wt% of TiO2and 0.3 wt% of ZnO nanofillers had achieved a maximum EMI SE of 11.4 dB at X-band frequency of 8–12 GHz.

Enhanced piezoelectric energy harvesting using hybrid composites of MWCNTs and partially-reduced GO in RTV-SR for stable voltage generation

Recent studies have explored the use of flexible devices for piezoelectric energy harvesting, which can generate energy at a few volts on a laboratory scale. In this context, multiwall carbon nanotubes (MWCNTs), partially-reduced GO (p-rGO), and their hybrid composites based on room temperature vulcanized silicone rubber (RTV-SR) have emerged as innovative and novel approaches for energy production. The composites were prepared by mixing an RTV-SR solution with MWCNTs and p-rGO powder as fillers, resulting in improved mechanical properties and reinforcement of the RTV-SR matrix. The p-rGO was synthesized from graphite nanoplatelets (GNP) using the modified Hummers' method, followed by chemical and thermal reduction. The MWCNTs were used as received from the supplier. Characterization techniques such as scanning electron microscopy, x-ray diffraction, transmission electron spectroscopy, and atomic force microscopy revealed that the p-rGO consisted of less than five layers stacked in a crystalline domain. Static mechanical property analysis demonstrated that MWCNTs exhibited exceptional filler characteristics compared to other fillers studied. Piezoelectric energy harvesting measurements were performed, and the results indicated higher voltage generation for MWCNTs; however, it exhibited instability and a decline in performance after a few cycles due to electrode cracking. In contrast, the hybrid composite demonstrated stable voltage generation. Moreover, walking and running activities may generate renewable, simple, and sufficient voltage to power light-emitting diodes (LEDs).

Lead-Free Piezoelectric Energy Harvester Based on 2D Bismuth Titanate.

The use of two-dimensional (2D) layered materials with a noncentrosymmetric structure dramatically increases the potential of nanoscale electromechanical systems and electronic devices. In this work, liquid-phase exfoliation of bulk bismuth titanate was employed to synthesize atomically thin 2D sheets and fabricate a high-performance piezoelectric energy harvester. The structural and morphological properties of the 2D sheets were analyzed, confirming their phase purity and layer formation. Piezoelectric properties of the 2D sheets were evaluated using Piezoresponse Force Microscopy (PFM), demonstrating a high d33 piezoelectric coefficient of 40 pm/V in a few-layer bismuth titanate nanosheet. A prototype energy harvesting device was fabricated with 2D bismuth titanate as the active material. The piezoelectric response of the fabricated device was recorded at different frequencies and forces, which yielded a maximum d33 of 57.8 pC/N at 1 Hz. Such a solid electromechanical performance at a relatively infinitesimal input response indicates that 2D bismuth titanate can be useful for piezoelectric energy harvesting applications.

Finite element modeling of piezoelectric cantilever-beam energy harvester

Piezoelectric energy harvesting from mechanical vibrations has attracted considerable attention during the last decade. The homogeneous harvesters were studied experimentally or numerically by various models such as single degree of freedom (SDOF) modeling, finite element (FE) modeling as well as using analytical solutions. In this work, FE models for simulating a piezoelectric beam bimorph power harvester consisting of a laminated piezoelectric beam, a proof mass, and an electrical load (series or parallel connections) configurations are developed. The effects of the material and size of the substrate, the proof mass have been studied on the resonance frequencies and the output parameters of the piezoelectric generator (PEG). Numerical results obtained using the proposed procedure for piezoelectric bimorph power harvesters are in good agreement with the experimental data available in the literature. The proposed method can be used for modeling accurately this class of energy harvesting devices.

Understanding the Enhanced Osmotic Energy Conversion in Heterogeneous Membranes Using Engineered Branched Alumina Nanochannel Membranes

Heterogeneous membranes with two composite layers of distinct pore sizes have emerged as promising candidates for efficient osmotic energy extraction from salinity gradients. Previous studies about heterogeneous membranes report a strong link between the induced diode‐like rectification property and improved osmotic energy conversion performance. Nevertheless, the inherently large interfacial resistance of heterogeneous membranes may offset such enhancement. To further understand the osmotic energy conversion behavior in heterogeneous membranes, a series of the branched alumina nanochannel (BAN) membranes consisting of large stem channels interconnected with small branched channels are designed. The interconnected and orderly aligned structure of the stem and branched channels ensures high effective driving force and ion selectivity while reducing interfacial resistance at the same time. Experimental and simulation results confirm the rectification effect induced by the asymmetric pores of BAN, which can achieve an osmotic power ≈130% higher than that of the conventional cylindrical nanochannel membranes. Additionally, a power density as high as 5.42 W m−2 is obtained by mixing seawater and river water, surpassing most of the existing heterogeneous membranes and the commercial benchmark. The BAN membrane proposed in this work provides a promising platform for the development of highly efficient osmotic energy harvesting devices.

Asymmetry stagger array structure ultra-wideband vibration harvester integrating magnetically coupled nonlinear effects

Traditional energy harvesters often have limitations in terms of bandwidth and power output, resulting in poor performance. This study reports a multi-strategy ultra-wideband energy harvesting device that utilizes an asymmetry, stagger array, magnetic coupling, and nonlinearity strategies to achieve high power output over an ultra-wideband frequency range without the need for external power input. The energy harvesting device consists of a base, two elastic beams, and two sets of asymmetric palm-shaped piezoelectric cantilever beam structures, each with a magnet attached at the tip. By reasonably arranging the palm-shaped mechanism and magnets, a magnetic coupling effect is introduced to achieve high power density output at non-resonant frequencies. Numerical analysis is conducted to evaluate the performance of the proposed structure, assess the influence of structural parameters, and establish a dynamic model to analyze the energy harvesting device. Experimental results demonstrate that the structure achieves a maximum power output of 60.49 mW at 19.9 Hz and 0.5 g, with a peak power density of approximately 8.065 × 103 W/m3. Within an ultra-wideband frequency range that spans 6 Hz to 64.2 Hz, the energy harvester maintains an output voltage which is more than 5 V. Furthermore, temperature and humidity monitoring are performed using Bluetooth sensors to adaptively assess the energy harvesting device, eliminating the need for lithium batteries and ensuring stable signal transmission. The device can be utilized for condition monitoring in any unstable vibration environment, contributing to the realization of distributed monitoring in the Internet of Things (IoT).

Generative optimization of bistable plates with deep learning

Bistate plates have found extensive applications in the domains of smart structures and energy harvesting devices. Most bistable curved plates are characterized by a constant thickness profile. Regrettably, due to the inherent complexity of this problem, relatively little attention has been devoted to this area. In this study, we demonstrate how deep learning can facilitate the discovery of novel plate profiles that cater to multiple objectives, including maximizing stiffness, forward snapping force, and backward snapping force. Our proposed approach is distinguished by its efficiency in terms of low computational energy consumption and high effectiveness. It holds promise for future applications in the design and optimization of multistable structures with diverse objectives, addressing the requirements of various fields.

Hybrid energy-harvesting device driven by membrane-based CO2 capture

Hybrid energy-harvesting device driven by membrane-based CO2 capture

Graphene wettability: Fundamentals, modulations, and applications in energy fields

Over the last decade, there has been a remarkable surge in the development of graphene-based energy generation, storage, transduction, and harvesting devices, driven by the exceptional electronic, optical, thermal, chemical, and mechanical properties of graphene. Notably, the tunable wettability of graphene offers an intriguing opportunity to enhance the performance of energy systems that utilize or involve water during device fabrication and usage stages, such as solar cells, nanogenerators, and supercapacitors. In this review, we provide an extensive overview of the latest research progress in the intrinsic wettability of graphene and its influencing factors, including substrate, contamination, defects, doping, and layer number. Subsequently, we highlight the representative applications in water-involved energy fields of high-quality graphene films synthesized via chemical vapor deposition. Lastly, we discuss current challenges in adopting graphene in the energy fields and propose future directions to promote the adoption of graphene in water-involved energy devices. Overall, this review presents critical insights into the significance of graphene wettability in advancing both the fundamental research and practical applications of graphene in energy fields.

Machine learning-based optimization of segmented thermoelectric power generators using temperature-dependent performance properties

Segmented thermoelectric generators (STEGs) provide an excellent platform for thermal energy harvesting devices because they improve power generation performance across a broad range of operating temperatures. Despite the benefit of direct thermal energy-to-electricity conversion, conventional STEG optimization approaches are unable to provide a systematic method for selecting the optimal multiple stacks of p- and-n-type thermoelectric materials (TEs) legs from a set of numerous TE materials. In this study, we propose a systematic optimization method based on machine learning to find the optimal STEG for performance maximization. A deep neural network (DNN) is trained using an initial dataset generated via the Finite Element Method (FEM), with inputs including the temperature-dependent properties of p- and n-type TE materials, the lengths of each segment, and external loads, as well as the corresponding performance outputs. The trained DNN captures the inherent nonlinear relationship between these inputs and outputs. The combination of a trained DNN and a genetic algorithm (GA) efficiently navigates a vast design space using 88 p-type and 70 n-type TE materials along with device factors. It formulates four stacked segment pairs in p- and n-leg TEGs, targeting new superior designs with enhanced power, efficiency, or both. The DNN is iteratively refined via active learning (AL) by incorporating new superior STEG designs to enhance prediction accuracy. The optimized STEGs exhibit power and efficiency that are 1.91 and 1.5 times higher, respectively, than the top designs from the initial training dataset composed of 157,916 STEGs. Furthermore, compared to conventional TEG designs without segmentation, our method discovered numerous high-performing STEG designs.

Enhancing energy harvesting performance of bilayered parylene triboelectric nanogenerators through interfacial polarization

Self-powered multifunctional devices have found applications in various fields including internet of things, smart robotics, and wearable haptic technologies. Triboelectric Nanogenerators (TENGs) are particularly noteworthy as they operate based on simple triboelectrification between contacting materials, and provide significantly higher output performance compared to other energy harvesting devices. In this study, we introduce soft bilayer structured films to significantly enhance the interfacial polarization and the resulting triboelectric output performance. The soft bilayer film is composed of two layers: a layer of parylene derivatives with different functional groups and a composite layer of polydimethylsiloxane (PDMS) embedded with multi-wall carbon nanotube (MWCNT). The parylene-deposited MWCNT-PDMS films effectively induce interfacial polarization due to the difference in permittivity between the parylene derivatives and MWCNT-PDMS, resulting in substantial improvement in triboelectric performances. Moreover, the specific functional groups present in the parylene monomers significantly affect the triboelectric polarity of the parylene-deposited bilayer films. The bilayer films deposited with parylene including fluorine, methyl hydroxyl, and hydroxyl groups, which improve the electron-withdrawing capability, exhibit negative triboelectric properties. In contrast, the bilayer film deposited with parylene including methyl amine group, which enhances the electron-donating ability, exhibits a positive triboelectric property. Owing to the highly improved interfacial polarization in the parylene-deposited bilayer films, our TENG consisting of paired bilayer films demonstrates superior output performance (4.57 W/cm2 and 10.28 W/cm2 for contact and separation step, respectively) compared to devices based solely on single layers of parylene- or PDMS (less than a few of mW/cm2). Our approach to designing layer-structured dielectric films offers a simple yet effective method to significantly enhance the output performance of self-powered flexible devices through improved polarization.

A comparative DFT study of CdKF3 and CdKCl3 halide perovskite materials for energy harvesting applications

Lead-free halide perovskites have been investigated as promising materials for energy harvesting and thermoelectric device applications. The current article thoroughly explains the electronic behavior, stability, optical and thermoelectric characteristics of CdKF3 and CdKCl3 halide perovskite. For structural stability, the elastic constant and phonon dispersion of both halides are investigated. Additionally, thermodynamic stability is demonstrated by the investigation of formation energy (-2.45 to −1.89 eV). The ductile nature of both halides is confirmed by calculating the Poisson ratio, and their significance for the manufacturing of devices. The direct bandgap nature (2.65 eV and 0.9 eV) of both halides is observed through electronic band structures using mBJ-GGA, which has been employed to obtain more precise results for optoelectronic applications. Both halides show remarkable optoelectronic performance, with low reflectivity, high optical absorption, and conductivity. Thermal and electrical conductivity are also used to study the thermoelectric characteristics. Both halides show the figure of merit (ZT) near unity, ZT indices highlight their importance for thermoelectric devices.

Tribological and morphological properties of bentonite nano‐clay/CaCO3 reinforced high‐density polyethylene nanocomposites

AbstractElastomeric polymers such as high‐density polyethylene, have a variety of desirable features, that have supplanted traditional materials. However, high‐density polyethylene (HDPE) shows inadequate wear resistance, which limits its use for industrial applications, particularly in low‐load‐bearing applications such as flexible energy harvesting devices and sensors. The current work is engrossed in investigating the influence of hybrid reinforcements CaCO3 particles and bentonite nano clay as secondary reinforcements in high‐density polyethylene (HDPE)‐based composites on the wear and friction properties. The reinforcements were melt compounded with HDPE using a Brabender mixer and sampled using an injection molding machine. The wear test (ASTM G‐99‐04) was performed by a pin‐on‐disk tribo‐tester. In comparison to a base matrix, the synthesized hybrid composite achieved the maximum improvement in wear rate of 93%. The results revealed that there is a significant improvement in wear resistance. Morphological analysis revealed that due to the encapsulation and compatibilization effect of bentonite nano clay the hybrid composite exhibited improved wear performance. The results signify the synergistic effect of filler particles resulted in sufficient bonding for stress transfer due to the encapsulation of CaCO3 by nano clay. The wear mechanism observed optically was abrasion, fatigue, and adhesion wear that changed with the change in the weight percent of nanoparticles. Finally, the prepared composite with enhanced tribological properties such as low wear rate, low friction coefficient, and enhanced morphology can be used in low load‐bearing wear applications such as turbo nanogenerators and piezo nanogenerators.Highlights Bentonite nano clay and CaCO3 dispersed homogeneously in HDPE matrix. Wear resistance of HDPE increases by reinforcing particles (nano‐clay and CaCO3). Micro‐cutting, deformations, and particle husks were the possible wear mechanism. Encapsulation effects the hybrid composite to exhibit improved wear performance.

Progress of Triboelectric Nanogenerators with Environmental Adaptivity

AbstractAs a distributed environmental energy harvesting device, triboelectric nanogenerators (TENGs) inevitably encounter different and extreme application scenarios, such as environment with high temperature, high humidity, corrosion condition, frequent mechanical stimulus, and physical damages, which resulting in triboelectric performance degradation either by damaging device structure or reducing surface potential, and accelerating dissipation of surface bound charge. Therefore, tremendous efforts are dedicated to improving the TENG performance, enabling devices are competent in sustaining various challenging conditions. This review summarizes and highlights the latest research progress of strategy to achieve TENGs with high environmental adaptivity in three representative application fields of interfacial devices, wearable devices and implantable devices, aiming to gain insights in terms of material selection, structural design, preparation technology, working mode and integration strategy. The future development of the TENG would transform from static to dynamic device that possesses multifunction, high stability, autonomous response and actuation ability to adapt complex application environment. It is hoped that this review article could steer the development of environment‐adaptive TENGs to a higher level.

Efficiency Improvement of Energy Harvesting Device Using Light Pressure Through Plasmon Coupling at the Interface Between Grained Ag Layer and Au Nanoparticles

AbstractElectricity generation using the piezoelectric effect is an important energy harvesting method. In this study, a solar radiation pressure‐driven crater‐shaped light pressure electric generator (LPEG) device with a Pb(Zr0.52, Ti0.48)O3 (PZT) piezoelectric layer and grained Ag layer is fabricated on GaAs(100) wafer. The electrical output of the device is improved by adsorbing Au nanoparticles (AuNPs) on the Ag layer with the surface of closely connected Ag nanoparticles (AgNPs). By controlling the size and concentration of the AuNPs, a maximum power density of 867.5 µW cm−2 is obtained under a solar simulator (AM 1.5G), which represents a 151.7% improvement over the case without AuNP adsorption. The results of Raman spectra, finite‐difference time‐domain (FDTD) simulations, and COMSOL Multiphysics demonstrate that the newly formed hotspots between AgNPs─AuNPs and AuNPs─AuNPs enhance the electric field of the incident light significantly and extend the region where the electric field is maximally amplified to 600–800 nm, resulting in increased solar radiation pressure on the PZT piezoelectric layer.

Simultaneously Enhanced Energy Harvesting and Storage Performance Achieved by 3D Mix‐Phase Mose2‐Nise/NF

AbstractAs an energy harvesting device, the newly emerged thermocell has attracted great interest. However, it requires an additional energy storage device to complete a functional recycling system. As the core part of energy harvesting and storage devices, the design of electrodes with both high thermoelectric and electrochemical conversion efficiencies is particularly important. Herein, a high‐performance thermocell and supercapacitor device are constructed by employing the same mix‐phase MoSe2‐NiSe/NF electrode for both energy harvesting and storage. The thermocell exhibits an enhanced Seebeck coefficient of −1.69 mV K−1 and a superior output of 0.58 mW m−2 K−2 for low‐grade heat harvesting. Meanwhile, the supercapacitor device shows a great energy density of 54 Wh kg−1 at a power density of 806 W kg−1 and excellent cycling stability with a 92.8% retention rate after 50 000 cycles. This work offers a universal approach for the rational design of synergistic electrode materials to simultaneously achieve high‐energy harvesting and storage devices and lays a foundation for the recycling system of thermoelectric harvesting, conversion, and storage.

A Generalized Residue Number System Design Approach for Ultralow-Power Arithmetic Circuits Based on Deterministic Bit-Streams

The peak power consumption has become an important concern in the hardware design process of some of today’s applications, such as Energy Harvesting (EH) and Bio-Implantable (BI) electronic devices. The limited peak harvested power in EH devices and heating concerns in BI devices are the main reasons for power control’s importance in these devices. This paper proposes a generalized design approach for ultra-low-power arithmetic circuits. The proposed circuits are based on Residue Number System (RNS) combined with deterministic bit-streams. The resulting circuits can be used in systems with a restricted power budget. We suggest several approaches to design generic hardware-efficient adders, multipliers, multiply-accumulate units (MAC), forward converters (FC), and reverse converters (RC). Using the proposed approach, designing these components for any moduli of the RNS can be performed through simple bit-width adjustments in the circuits. The synthesis results show that the proposed adder achieves, on average, 69% and 2% lower area compared to the bit-serial and a state-of-the-art RNS adder, respectively. Furthermore, the proposed multiplier outperforms the bit-serial, interleaved, and a state-of-the-art design for multiplying RNS numbers by, on average, 57%, 60%, and 77% in terms of power consumption, respectively. The efficiency of our approach is shown via two essential applications, digital signal processing and machine learning. We implement an FFT engine using the proposed method. Compared to prior RNS implementations, our design achieves 47% lower power consumption. We also implement a CNN accelerator’s Processing Element (PE) with the proposed computation elements. Our design provides considerable speedup and lower power consumption compared to a state-of-the-art ultra-lower-power design.

Investigation of manganese doped BaSe for energy harvesting and spintronics devices

Abstract The incorporation of magnetism to a solid material may drastically alter its electrical transport behavior, providing a way to modify the magneto-optoelectronic and thermoelectric features that have recently drawn a lot of scientific attention. In this regard, we utilized density function theory (DFT) based full potential linearized augmented plane wave (FP-LAPW) approach to study doping effect of Mn on physical characteristics of barium selenide (BaSe). Pristine BaSe is nonmagnetic semiconductor with indirect bandgap of 2.11 eV. Concentration dependent Mn doping in BaSe introduces spin polarized intermediate bands in the vicinity of Fermi level primarily composed of Mn-3d orbitals. Asymmetric band profiles indicate the ferromagnetic semiconductor nature of of Mn doped BaSe compounds. Total magnetic moment value of 5.0 μ B, 10.0 μ B, and 20.0 μ B are obtained for corresponding Ba1−xMnxSe (x = 6.25%, 12.5%, 25%) systems. Furthermore, the analysis of optical and thermoelectric characteristics reveals the importance of studied alloy for application in advanced technologies including low energy light absorbers and thermoelectric generators.