Practical Power Source Research Articles

Moisture-driven energy generation by vertically structured polymer aerogel on water-collecting gel

In the realm of energy harvesting, free-standing, film-type, moisture-driven electricity generators (MEGs) based on polymer hydrogels with moisture-retaining capability are promising as a convenient and practical power source, making them potentially suitable for various self-powered, wearable, and patchable electronic devices. Their performance is, however, substantially degraded under low-humidity (<40%) conditions owing to the limited water supply to the device. This study presents a high-performance film-type MEG that functions at a low humidity of 20%. The MEG is based on an ion-selective polymer aerogel as an electricity-generating layer, constructed on a water-collecting gel as a water reservoir. The water-collecting gel in the bi-layered MEG absorbs moisture even under low-humidity conditions and efficiently delivers moisture to the electricity-generating aerogel layer. The energy-harvesting ability of the electricity-generating aerogel layer is further facilitated by its characteristic vertical microstructure, which comprises aerogel pores directionally grown on the frozen water-collecting gel during the freeze-drying process. The low humidity-tolerant MEG generated a stable open-circuit voltage of 1.1 V for more than 500 min even under dry conditions (20% relative humidity). Various self-powered electronic applications are demonstrated with the low-humidity-tolerant, bi-layered MEGs in dry environments. This study provides new insights for designing future MEGs for operation in low-humidity environments, further facilitating the development of green and sustainable power generation.

A Triboelectric Nanogenerator Based on Pendulum‐Rotation Transmission Mechanism for Harvesting Continuous Low‐Frequency Mechanical Energy

AbstractHarvesting the omnipresent mechanical energy emerges as an essential solution in combating environmental pollution and alleviating energy deficits. However, the ultra‐low frequencies and variable amplitudes of most ambient mechanical energy pose significant challenges to effective energy harvesting. To address this issue, this paper reports an innovative triboelectric nanogenerator based on pendulum‐rotation transmission mechanism (PR‐TENG) designed for efficacious harvesting of continuous low‐frequency mechanical energy. It comprises two synergistic units: a transmission unit and a power‐generating unit. The transmission unit is capable of converting external low‐frequency mechanical excitations into unidirectional rotation. Through an internal speed‐increasing mechanism, the rotational speed of the rotor can be further elevated, thereby enabling the power‐generating unit to produce a frequency‐multiplied output and markedly improving the energy transduction efficiency. The mechanism of triboelectrification employed by the power‐generating unit further reduces the total weight of the device, thus advancing its portability. In addition, the coherent coaxial configuration of the device's components significantly enhances compactness and optimizes spatial efficiency. As a practical power source, the PR‐TENG is shown to be capable of directly powering LEDs. Owing to its distinctive operational mechanism and structural innovation, the PR‐TENG is a promising method to efficiently harvest low‐frequency mechanical energy from the ambient environment.

항적 데이터에 기반한 하이브리드 추진 연료전지 선박의 효율 평가

Efforts have been made to reduce the greenhouse gas emissions from ships by limiting the energy efficiency index, and net zero CO2 emission was proposed recently. The most ideal measure to achieve zero emission ship is electrification, and fuel cells are considered as a practical power source of the electrified propulsion system. The electric efficiency in the electrochemical reaction of fuel cells can be achieved up to 60% practically. The remaining energy is converted to heat energy but most of them are dissipated by cooling. In the author’s previous research, a hybrid propulsion system utilizing not only electricity but also heat was introduced by combining electric motor and steam turbine. In this article, long term efficiency is evaluated for the introduced hybrid propulsion system by considering a virtual 24,000 TEU class container carrier model. To reflect a more practical operating condition, the actual navigation data of a similar real ship in the real world were collected from automatic identification system data and applied. From the result, the overall efficiency of the hybrid propulsion system is expected to be higher than a conventional electric propulsion fuel cell ship by 30%.

Ti3C2Tx MXene/dopamine-modified polypyrrole flexible composite electrodes with application in energy storage devices

Ti3C2Tx MXene is a new 2D material with great potential for supercapacitor applications. Here, we propose a straightforward strategy to fabricate the composite electrode based on MXene. Firstly, the addition of dopamine-modified polypyrrole (DA-PPy) nanofibers prevents the MXene restacking during the fabrication process of the films by vacuum-assisted filtration and makes it easier for the rapid and reversible intercalation/deintercalation of ions. And then, the DA-PPy nanofibers provide more conductive channels for the charge carriers and effectively improve the electrochemical performance of the composite films. The composite electrode yielded the highest specific capacitance of 384.9 F g−1 at 1 A g−1 with 86.7 % capacitance retention after 3000 cycles at 2 A g−1. The CV curves of the supercapacitor assembled with the composite electrode and the conductive carbon cloth maintain an approximately rectangular shape, displaying the relatively ideal capacitive behavior. In addition, the MXene/DA-PPy film shows potential for triboelectric nanogenerator (TENG) applications. The MXene/DA-PPy 9–1 film was combined with the triboelectric layer to fabricate the flexible single-electrode type TENG, demonstrating its potential as the practical power source that can power small electronics, and be a promising candidate for energy storage applications.

An eccentric-structured hybrid triboelectric-electromagnetic nanogenerator for low-frequency mechanical energy harvesting

With the increasing aggravation of the environmental pollution and energy crisis, exploiting clean and renewable energy becomes imperative for human existence and development. In this paper, an eccentric-structured hybrid triboelectric-electromagnetic nanogenerator (EHNG) is proposed to harvest low-frequency mechanical energy. It mainly contains two parts, – a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG). Exploiting the unique eccentric structure, the EHNG can effectively transfer one-dimensional mechanical motion of an object to the rotation of the eccentric rotor, resulting in electricity generation. In comparison to a separate energy harvesting unit, the hybrid nanogenerator operates beyond the single energy harvesting mode, showing preferable electrical output performances including a broader output range and shorter time of voltage boosting. In terms of energy storage, the EHNG provides not only a higher saturation charging voltage and continuous charging from the TENG part, but also a rapid charging speed in the early charging phase from the EMG part. As a practical power source, the EHNG is shown to be capable of directly powering LEDs. The present work develops an effective and sustainable technique to maximally harvest mechanical energy from the environment.

A rotational vibration energy harvester for near-zero-energy applications in railway environment

The vibration in the railway environment contains a huge amount of available mechanical energy, which can be utilized as a practical power source for low-power independent distributed appliances. This paper proposed a rotational vibration energy harvester (RVEH) based on a linear cam mechanism for near-zero-energy applications in railway environment. The RVEH system mainly consists of a motion conversion mechanism (MCM) and electromagnetic generators. The motion conversion mechanism realizes the motion conversion from vibration to uni-directional rotation based on a linear cam and a one-way rectifier. The electromagnetic generators convert kinetic energy into electrical energy. The test shows that the electric outputs of the proposed RVEH is improved under vibration excitations compared with the conventional vibration energy harvester (VEH, the RVEH without a one-way rectifier). Also, the RVEH has a comparatively long duration of electric outputs after the vibration excitation, suitable for the intermittent vibration excitation input. And the RVEH can operate as a power supply, producing output characteristics of an average output power of 66 mW and a peak output power of 0.15 W, sufficient to power 155 LEDs in series or a thermometer. It is foreseeable that the RVEH is a promising self-powered solution for applications in railway environment.

Zinc Passivation in Zinc-Slurries Operated Beyond the Zincate Solubility Limit

Recently, zinc-air batteries have received revived interest as one of the proposed post lithium-ion technologies. This revival is driven by the demand for safe and environmentally friendly energy storage solutions for fluctuating renewable energy. These energy storage systems need to address variable power, capacity and profitability requests. Zinc-air-flow batteries with high specific energy density, low-cost, highly available and eco-friendly active materials are suitable to fulfill these requirements. The use of a flow battery type with zinc-particles suspended in an alkaline solution (zinc-slurry) in addition to high performance oxygen-reduction electrodes enables the development of high-power zinc-air batteries. Usually, the energy density of zinc-air-flow cells is limited by the solubility of the oxidation products in the electrolyte. In our cell, the electrolyte is supersaturated with oxidation products, before finally ZnO precipitates from the electrolyte. The cell is therefore operated beyond zincate solubility limit, which allows higher specific capacities than reported in literature, even though the zincate solubility of the electrolyte is much lower than reported [1].The flow cell has an active area of 100 cm² and incorporates a copper plate as current collector for the zinc-suspension electrode and an oxygen reduction electrode with gas-diffusion layer (supplied by Covestro). The zinc-slurry contains zinc-particles (supplied by Grillo) suspended in an alkaline solution (30 wt.-% KOH) and stabilized with polyacrylic acid.One of the main limiting factors of the specific capacity of the zinc-slurry is passivation. While the passivation of stationary electrodes in flowing or quiescent electrolytes is fairly well understood, see e. g. [2], there is no literature on the passivation behaviour of zinc-slurry electrodes. In this study we determined the starting point of ZnO precipitation and the critical factor for the passivation of these anodes by analysing cell voltage, potential of the zinc electrode and the zincate concentration in the liquid phase of the zinc-slurry. Depending on parameters like current density and additive selection, it is possible to reach specific capacities of 287 mAh/gslurry or 574 mAh/gzinc. Appleby, A.J. and M. Jacquier, The C.G.E. circulating zinc/air battery: A practical vehicle power source. Journal of Power Sources, 1976. 1(1): p. 17-34.Bockelmann, M., et al., Electrochemical characterization and mathematical modeling of zinc passivation in alkaline solutions: A review. Electrochimica Acta, 2017. 237: p. 276-298.

Boosting the lifespan of magneto-mechano-electric generator via vertical installation for sustainable powering of Internet of Things sensor

Sustainability is essential for magneto-mechano-electric (MME) energy harvesters that convert low-frequency magnetic noise into useful electrical energy to be considered a practical power source for implementing real-life Internet of Things (IoT) sensor networks. In this study, we propose a vertically installed MME energy harvester based on a piezoelectric lead magnesium niobate-lead zirconate titanate (Pb(Mn1/3Nb2/3)O3-Pb(Zr,Ti)O3, PMN-PZT) single-crystal macro fiber composite cantilever. The MME harvester generates 12.2 mW output power from a low-amplitude stray magnetic field of 2.5 Oe and exhibits a long-term usable lifetime of 2.5 × 109 cycles while maintaining over 90 % of its output. An accelerated life test method is employed to predict the usable lifetime of the MME harvester using an inverse power law-Weibull model with accelerating stress of magneto-mechanical vibration-induced strain. In addition, a standalone wireless environmental monitoring system is demonstrated to operate for 10 weeks by exploiting the harvested power from stray magnetic fields (~2.2 Oe) near the power cables of home appliances. This study paves the way for lifetime assessment and prediction of sustainable MME harvesters to increase the practicability of self-powered IoT devices in smart infrastructures.

High power generation in moisture via alkaline-treated MoS2 coating sponge

Hydroelectricity is an emerging novel electricity generation phenomenon that can generate electric power simply when nanostructured materials are in direct contact with omnipresent liquid water or moisture. In this work, after alkali treatment, a molybdenum disulfide (MoS2) sponge can produce a high-output voltage of about 430 mV and a remarkable output current of 62 μA under a relative humidity of 80%, which is over three times and 20 times as compared with that of pure MoS2 coating sponges, respectively, and it also achieves a continuous electric output over 1 h with good stability. The increasing number of movable cations after alkali treatment probably results in the improvement of power generation performance. Demonstrating the ability of the MoS2 coating sponges to function as a practical power source, the output voltage of the devices is further scaled up to 10 V by simple series connections, and capacitors charged to 5 V are able to power an electronic screen with single-chip computers.

On-demand solid-state artistic ultrahigh areal energy density microsupercapacitors

Practical application of microsupercapacitors (MSCs) has been plagued by challenging task of achieving high energy density, shape/configuration diversity, and mechanical flexibility. Here, we present on-demand solid-state artistic ultrahigh areal energy density MSCs (a-MSCs). Direct-ink-writing (DIW) printing of rheology-tuned electrode inks and ultraviolet-curable gel polymer electrolyte inks allows the construction of thick electrodes with microscale features/arbitrary form factors and ionic isolation between unit cells (enabling electrochemical tailoring of voltages and capacitances in a single a-MSC). A nickel/gold-plated polyimide substrate is introduced as a flexible current collector that allows an increase in areal mass loading of electrodes. A DIW-printed polydimethylsiloxane layer shifts the location of a neutral plane to electrode-current collector interface to improve flexibility. The resulting a-MSC exhibits high areal energy density (61.34 µWh cm−2) and on-demand (in-series/in-parallel) cell configuration with artistic versatility. Moreover, the a-MSC is aesthetically unitized with complex-shaped electronic devices, acting as a customized practical monolithic power source.

An eccentric mass-based rotational energy harvester for capturing ultralow-frequency mechanical energy

The omnipresent ultralow-frequency vibrations and swings contain a huge amount of mechanical energy, but the low harvesting efficiency hinders their application as a practical power source. To address this issue, this paper reports an innovative eccentric mass-driven rotor (EMDR) that is capable of transforming ultralow-frequency excitations to uni-directional rotation. This motion transformation is enabled by a two-layered cantilevered plectrum that provides a sufficiently large driving stiffness for the anticlockwise rotation of a rotator but a very small sliding friction resistance during its clockwise rotation with respect to the rotator. A rotational energy harvester (REH) based on the EMDR is designed and fabricated, which exhibits remarkably improved electric outputs under ultralow-frequency excitations as compared with the conventional REH without the EMDR. Moreover, the designed REH has a comparatively long duration of electric outputs after the applied excitation vanishes, making it adapt well to the real-world excitations featuring intermittent availability. When the designed REH is attached to the human arm or leg, the generated electric energy under jogging is sufficient for running some small electronic devices. This study demonstrates the promising application foreground of the proposed EMDR in realizing high-output ultralow-frequency energy harvesters.

A human-machine interactive hybridized biomechanical nanogenerator as a self-sustainable power source for multifunctional smart electronics applications

Biomechanical energy harvesting has been attracting increased attention for powering electronic devices and reducing battery dependency. Here, we report a human–machine interactive hybridized biomechanical nanogenerator (HMI-HBNG) including an electromagnetic generator (EMG) using a Halbach magnet array and an interdigitated electrode-based triboelectric nanogenerator (TENG). The Halbach magnet array enhances the magnetic flux density, increasing the output power of the EMG eightfold. Introducing a nanowire structure in a polytetrafluoroethylene (PTFE) film and incorporating a novel phase inversion technique for microstructure modifications in the nylon/11 film increase the energy harvesting efficiency of the TENG. The performance of the HMI-HBNG is investigated from different perspectives and shows a maximum output power density of 185 W/m2 across an optimum load resistance of 1.6 kΩ at 5 Hz under 20 m/s2 acceleration. In a human motion experiment, the HMI-HBNG charges a Li-ion battery (18 mAh) from 0 V to 3 V in approximately 10 s and operates multiple electronics devices simultaneously for 3 min. By using a customized power management circuit, the HMI-HBNG can provide a self-sustainable power source for driving multifunctional smart electronic devices, including Bluetooth computer mice, smartwatches, and smartphones. This work represents significant progress toward a self-powered system and practical power source.

A miniaturized, self-sustaining, and integrable bio-solar power system

Abstract We demonstrate a practical and sustainable bacterial power source for low-power electronic applications. Self-sustainable electricity is produced from revolutionarily structured microliter-scale bio-solar cells using a co-culture of heterotrophic and autotrophic bacteria. Two bio-solar cells are integrated on a single chip and connected in series, continuously generating light-responsive electricity from heterotrophic bacterial respiration with the organic substrates produced by photosynthetic autotrophs. Agar-based anolyte, catholyte, and salt-bridge provided solid-state ionic environments for more efficient syntrophic interactions between co-cultures without bacterial competition, further enhancing the device performance and lifespan. The solid-phase platform allows versatile device configuration in a small footprint without a cumbersome fluidic feeding system and permits easy integration and operation with solid-state applications. The device is sealed with a gas-permeable polydimethylsiloxane (PDMS) membrane to facilitate gas exchange to the bacteria and cathodic reactions, even ideally allowing for replenishing bacterial gasses from environments for self-sustainable energy harvesting. A DC-DC booster circuit is integrated with the stacked bio-solar cells to increase the operational voltage (~500 mV) to a maximum output of >3 V for self-powering an on-chip, light-emitting diode (LED). This is the first demonstration of the microliter-scale bio-solar cell as a practical power source.

MEMS-based Micro-scale Wind Turbines as Energy Harvesters of the Convective Airflows in Microelectronic Circuits

As an alternative to conventional batteries and other energy scavenging techniques, this paper introduces the idea of using micro-turbines to extract energy from wind forces at the microscale level and to supply power to battery-less microsystems. Fundamental research efforts on the design, fabrication, and test of micro-turbines with blade lengths of just 160 µm are presented in this paper along with analytical models and preliminary experimental results. The proof-of-concept prototypes presented herein were fabricated using a standard polysilicon surface micro-machining silicon technology (PolyMUMPs) and could effectively transform the kinetic energy of the available wind into a torque that might drive an electric generator or directly power supply a micro-mechanical system. Since conventional batteries do not scale-down well to the microscale, wind micro-turbines have the potential for becoming a practical alternative power source for microsystems, as well as for extending the operating range of devices running on batteries.

Reliable DC voltage generation based on the enhanced performance triboelectric nanogenerator fabricated by nanoimprinting-poling process and an optimized high efficiency integrated circuit

Intensive research on triboelectric nanogenerators (TENGs) has been established since they were first introduced, but their application as a practical power source remains to face several challenges. Herein, we report a one-step process of thermal nanoimprinting and simultaneous electric poling to increase the total energy obtained by each cycle of a TENG with a ferroelectric thermoplastic polymer. The synergetic effect generated by the resultant formation of surface topography and the enhancement of effective dipole strength is systematically verified, and a wind energy harvester with enhanced electrical output performance is demonstrated. Furthermore, this paper also presents a novel integrated circuit (IC) that can generate reliable DC voltage even when an intermittent and irregular electrical output of the TENG is supplied. In the automatic control of the moment when the electrical output of the TENG is transferred into the electronic device, the present IC shows a conversion efficiency over 70% even when the input power is about 2.5 μW. This work intensively addresses the issues hindering the utilization of TENGs as a practical and reliable power source and thus may serve as a reference in the development of TENG-based self-powered systems in the future.

Rationally designed rotation triboelectric nanogenerators with much extended lifetime and durability

Triboelectric nanogenerators (TENG) is a promising route for harvesting ambient mechanical energy to obtain clean and renewable electricity. However, the durability of materials still limits its practical applications for continuous operation. Here, a radial-arrayed TENG was integrated with a transmission mechanism, which successfully maximized the sustainable operation with less triboelectric material wear and damage. Through the rational design of the transmission mechanism, triboelectric layers were first charged by the contact electrification due to the wave impact from the sides, and charges were transferred by the electrostatic induction continuously because of the tumbler's design. In this case, frictional resistance between the triboelectric layers were successfully eliminated, which largely enhances its robustness and durability. After running for 500 k cycles, there is only 1.8% degradation. The TENG could convert one single impact into multiple cycles of rotations, which improves the energy harvesting efficiency for sustainably driving and charging commercial electronics, immediately demonstrating the feasibility of the TENG as a practical power source with extended lifetime and durability. Given exceptional durability and unprecedented applicability resulting from novel designs, this work provides an attractive strategy for the study of triboelectric nanogenerator's durability and facilitates the development of the self-powered systems.

Self-Sustainable Wearable Textile Nano-Energy Nano-System (NENS) for Next-Generation Healthcare Applications.

Wearable electronics presage a future in which healthcare monitoring and rehabilitation are enabled beyond the limitation of hospitals, and self‐powered sensors and energy generators are key prerequisites for a self‐sustainable wearable system. A triboelectric nanogenerator (TENG) based on textiles can be an optimal option for scavenging low‐frequency and irregular waste energy from body motions as a power source for self‐sustainable systems. However, the low output of most textile‐based TENGs (T‐TENGs) has hindered its way toward practical applications. In this work, a facile and universal strategy to enhance the triboelectric output is proposed by integration of a narrow‐gap TENG textile with a high‐voltage diode and a textile‐based switch. The closed‐loop current of the diode‐enhanced textile‐based TENG (D‐T‐TENG) can be increased by 25 times. The soft, flexible, and thin characteristics of the D‐T‐TENG enable a moderate output even as it is randomly scrunched. Furthermore, the enhanced current can directly stimulate rat muscle and nerve. In addition, the capability of the D‐T‐TENG as a practical power source for wearable sensors is demonstrated by powering Bluetooth sensors embedded to clothes for humidity and temperature sensing. Looking forward, the D‐T‐TENG renders an effective approach toward a self‐sustainable wearable textile nano‐energy nano‐system for next‐generation healthcare applications.

A Nonencapsulative Pendulum‐Like Paper–Based Hybrid Nanogenerator for Energy Harvesting

AbstractThe newly invented triboelectric nanogenerator (TENG) is deemed to be a more efficient strategy than an electromagnetic generator (EMG) in harvesting low‐frequency (&lt;2 Hz) water wave energy. Various TENGs with different structures and functions for blue energy have been developed, which can be roughly divided into two types: liquid–solid contact electrification TENGs and fully enclosed solid–solid contact electrification TENGs. Robustness and packaging are critical factors in the development of TENGs toward practical applications. Furthermore, for fully enclosed TENGs, the requirements and costs of packaging are very high, and they can difficult to disassemble after enclosed, if there is something wrong with the devices. Herein, a nonencapsulative pendulum‐like paper based hybrid nanogenerator for energy harvesting is designed, which mainly consists of three parts, one solar panel, two paper based zigzag multilayered TENGs, and three EMG units. This unique structure reveals the superior robustness and a maximum peak power of zigzag multilayered TENGs up to 22.5 mW is realized. Moreover, the device can be used to collect the mechanical energy of human motion in hand shaking. This work presents a new platform of hybrid generators toward energy harvesting as a portable practical power source, which has potential applications in navigation and lighting.

A string-suspended and driven rotor for efficient ultra-low frequency mechanical energy harvesting

The abundant mechanical energy distributed in ambient environments features ultra-low frequency. Implementation of self-sustained low-power electronic systems is largely dependent on the efficient exploitation of the ubiquitous ultra-low frequency mechanical energy. This paper reports a fundamentally different approach for constructing high-output rotational energy harvesters on the basis of a novel string-suspended and driven rotor, which uses only two strings to suspend and actuate a rotor. Distinguished from the conventional energy harvesters that convert various mechanical motions to vibrations of a mechanical oscillator with high resonant frequency, the proposed approach converts vibrations or linear reciprocating motions to either rapid rotation motion or high-frequency small twisting vibration of a rotor, making the harvester well suited for harnessing ultra-low frequency mechanical motions. We demonstrate the superior performance of this approach by applying it to electromagnetic energy harvesting from ultra-low frequency vibrations and human body motions. Under a periodical excitation with amplitude of 23 mm, the fabricated electromagnetic energy harvester achieves 12.3 mW power with a matched resistive load (25 Ω) at 2.6 Hz. With human body motion as the energy source, the harvester can sustainably drive as well as charge various small electronic devices, manifesting the promising potential of the proposed approach for capturing ultra-low frequency mechanical energy as a practical power source.

Review on Solar Energy Monitoring Using Internet of Things

The IoT has a vision in which the web stretches out into certified conventional things. The IoT engages things to be recognized similarly as controlled remotely over existing structure foundation, making openings joining blend of the physical world into pc based frameworks, and acknowledging improved proficiency, exactness and cash related favoured position notwithstanding reduced human intercession. This advancement has various applications like Sun oriented urban networks, Savvy towns, Small scale cross sections; Sun oriented Road lights, and so on. This paper administers checking and controlling the voltage yield of sunshine based board kept at out of reach region and watching the yield in the server utilizing Web of Things (IoT). With the guide of this system, the checking and controlling method is made straightforward and powerful. Examination impacts on the practical power source use and power issues.