Large Capacitance Research Articles

Highly Stable Solid Contact Calcium Ion-Selective Electrodes: Rapid Ion-Electron Transduction Triggered by Lipophilic Anions Participating in Redox Reactions of CunS Nanoflowers.

Solid contact (SC) calcium ion-selective electrodes (Ca2+-ISEs) have been widely applied in the analysis of water quality and body fluids by virtue of the unique advantages of easy operation and rapid response. However, the potential drift during the long-term stability test hinders their further practical applications. Designing novel redox SC layers with large capacitance and high hydrophobicity is a promising approach to stabilize the potential stability, meanwhile, exploring the transduction mechanism is also of great guiding significance for the precise design of SC layer materials. Herein, flower-like copper sulfide (CunS-50) composed of nanosheets is meticulously designed as the redox SC layer by modification with the surfactant (CTAB). The CunS-50-based Ca2+-ISE (CunS-50/Ca2+-ISE) demonstrates a near-Nernstian slope of 28.23 mV/dec for Ca2+ in a wide activity linear range of 10-7 to 10-1 M, with a low detection limit of 3.16 × 10-8 M. CunS-50/Ca2+-ISE possesses an extremely low potential drift of only 1.23 ± 0.13 μV/h in the long-term potential stability test. Notably, X-ray absorption fine-structure (XAFS) spectra and electrochemical experiments are adopted to elucidate the transduction mechanism that the lipophilic anion (TFPB-) participates in the redox reaction of CunS-50 at the solid-solid interface of ion-selective membrane (ISM) and redox inorganic SC layer (CunS-50), thereby promoting the generation of free electrons to accelerate ion-electron transduction. This work provides an in-depth comprehension of the transduction mechanism of the potentiometric response and an effective strategy for designing redox materials of ion-electron transduction triggered by lipophilic anions.

Carbon Nanotube-Based Printed All-Organic Microelectrode Arrays for Neural Stimulation and Recording.

In this paper, we report a low-cost printing process of carbon nanotube (CNT)-based, all-organic microelectrode arrays (MEAs) suitable for in vitro neural stimulation and recording. Conventional MEAs have been mainly composed of expensive metals and manufactured through high-cost and complex lithographic processes, which have limited their accessibility for neuroscience experiments and their application in various studies. Here, we demonstrate a printing-based fabrication method for microelectrodes using organic CNT/paraffin ink, coupled with the deposition of an insulating layer featuring single-cell-sized sensing apertures. The simple microfabrication processes utilizing the economic and readily available ink offer potential for cost reduction and improved accessibility of MEAs. Biocompatibility of the fabricated microelectrode was suggested through a live/dead assay of cultured neural cells, and its large electric double layer capacitance was revealed by cyclic voltammetry that was crucial for preventing cytotoxic electrolysis during electric neural stimulation. Furthermore, the electrode exhibited sufficiently low electric impedance of 2.49 Ω·cm2 for high signal-to-noise ratio neural recording, and successfully captured model electric waves in physiological saline solution. These results suggest the easily producible and low-cost printed all-organic microelectrodes are available for neural stimulation and recording, and we believe that they can expand the application of MEA in various neuroscience research.

Mn-doped nickel-copper phosphides as oxygen evolution reaction electrocatalyst in alkaline seawater solution

Compared with traditional water electrolysis, electrolysis of seawater has larger resources and a brighter future. However, seawater contains more elements that have greater corrosive effects on electrodes; especially chloride ions (seawater contains more chloride ions) have the greatest impact. The existence of the corrosion problem creates greater difficulties in electrolyzing seawater, further limiting the efficiency of the electrocatalyst for electrolysis of seawater. In this paper, we report a Mn-doped Ni2P/Cu3P as an environmentally friendly monofunctional electrode for seawater electrolysis, which was made by a simple hydrothermal phosphatization operation method. The experimental results show that Mn-doped Ni2P/Cu3P presents overpotential of only 161 mV for oxygen evolution reaction (OER) at iR compensation of 90 and a current density of 10 mA cm−2. It has a small Tafel slope (25.15 mV dec−1) and a large capacitance (9.58 mF cm−2 on 1 × 1 nickel foam), which exceeds most reported oxygen evolution activities of non-precious metal-based electrocatalysts for electrolysis of alkaline seawater. The performance of Ni2P/Cu3P was probably significantly enhanced due to Mn doping by some characterization means. Through Density functional theory (DFT) analysis, it is known that the doping of Mn gives a large enhancement in the adsorption energy of water when Ni2P/Cu3P is electrolyzed with seawater. This paper provides train of thought for the exploration of excellent electrocatalysts for electrolysis of alkaline seawater.

Synergizing Battery-Powered Permanent Magnet Synchronous Motor Control with Integrated Modular Multilevel Converter Systems

This proposed work presents a comprehensive examination of a modular multilevel converter (MMC) combined with a permanent magnet synchronous motor (PMSM) for battery energy management in applications. In order to provide effective energy transfer and dynamic control, the Modular Multilevel Converter serves as a bridge between the battery system and the Permanent Magnet Synchronous Motor drive. By cleverly controlling energy flow and minimizing losses during charging and discharging cycles, the combination of MMC with PMSM seeks to increase energy efficiency and prolong battery life. Since the energy source provides all of the power for the motor, it runs at a constant pace. When the accelerating mode finishes, the energy storage receives just enough power to maintain a steady voltage. The energy storage system utilizes the majority of the renewable power generated by the electric motor when it is in deceleration mode to raise the voltage in the system. During the subsequent acceleration mode, the stored energy might be released the MMC-BESS, which combines a modular multilevel converter with a battery energy storage system, is gaining popularity due to its high adaptability and dependability. This system integrates batteries into a sub module. Sub-modular capacitor voltage fluctuations are caused by the significant reactive power that is generated through the workings of modular multilevel converters. To reduce the fluctuation, large capacitance capacitors is required, which would significantly increase the system's capacity. The proposed approach means to upgrade energy proficiency and execution in electric vehicle applications. By joining the benefits of battery power with the flexibility of MMC frameworks, the arrangement offers upgraded control accuracy, decreased misfortunes, and further developed adaptation to non-critical failure. This combination works with consistent power the executives, guaranteeing ideal use of assets while meeting severe execution prerequisites. Through exhaustive examination and recreation, the adequacy of this incorporated framework is illustrated, displaying propelling the field of electric vehicle impetus and power conversion potential.

Solution-processable low-voltage carbon nanotube field-effect transistors with high-k relaxor ferroelectric polymer gate insulator

Achieving energy-efficient and high-performance field-effect transistors (FETs) is one of the most important goals for future electronic devices. This paper reports semiconducting single-walled carbon nanotube FETs (s-SWNT-FETs) with an optimized high-k relaxor ferroelectric insulator P(VDF-TrFE-CFE) thickness for low-voltage operation. The s-SWNT-FETs with an optimized thickness (∼800 nm) of the high-k insulator exhibited the highest average mobility of 14.4 cm2 V−1s−1 at the drain voltage (I D) of 1 V, with a high current on/off ratio (I on/off >105). The optimized device performance resulted from the suppressed gate leakage current (I G) and a sufficiently large capacitance (>50 nF cm−2) of the insulating layer. Despite the extremely high capacitance (>100 nF cm−2) of the insulating layer, an insufficient thickness (<450 nm) induces a high I G, leading to reduced I D and mobility of s-SWNT-FETs. Conversely, an overly thick insulator (>1200 nm) cannot introduce sufficient capacitance, resulting in limited device performance. The large capacitance and sufficient breakdown voltage of the insulating layer with an appropriate thickness significantly improved p-type performance. However, a reduced n-type performance was observed owing to the increased electron trap density caused by fluorine proportional to the insulator thickness. Hence, precise control of the insulator thickness is crucial for achieving low-voltage operation with enhanced s-SWNT-FET performance.

Porous carbon-MnO2 heterostructures for high energy density aqueous ammonium-ion asymmetric supercapacitors

Aqueous ammonium-ion (NH4+) is gaining attention as a viable energy storage option due to the use of NH4+ as the charge carrier, offering advantages of resource abundance, safety, fast diffusion, and a unique storage mechanism. Despite these benefits, the development of storage devices with NH4+ as the charge carrier are still in the early stages, highlighting the crucial need to explore suitable electrode materials for the production of high-performance devices. In this study, broken porous carbon nanocages (BPCs) serve as the support structure to form a heterostructure with δ-MnO2 nanosheets (MnO2-BPCs) grown onto them, building aqueous NH4+ asymmetric supercapacitors (ASCs). Both MnO2-BPCs and BPCs act as host materials for storing aqueous NH4+, exhibiting high specific capacitance and long cycling durability. The assembled NH4+ ASCs present good capacitive performance, with a large specific capacitance of 223 F g−1 and capacitance preservation of 91.4 % over 10,000 cycles. The high energy density achieved by NH4+ ASCs is crucial for advanced energy storage thanks to their elevated specific capacitance and broad operating voltage. The balanced capacitive performance of the positive and negative electrodes is essential in enhancing the energy storage capabilities of NH4+ ASCs. This work provides a straightforward method for creating porous carbon-MnO2 heterostructures for NH4+ storage and paves the way for designing aqueous NH4+-based sustainable energy storage systems (SESSs) for capacitive energy storage.

A miniaturized dual band pass frequency selective surface insensitive to oblique angles and polarizations of wave

Abstract A Dualband Pass Frequency Selective Structure (DPSFSS) with miniaturized elements is proposed in this article. The miniaturized elements induce high inductance and capacitance values. The meandered line concept is used which extensively increases inductance of the dipole element. Very large capacitance is obtained between two meandered elements which have wide common area perpendicular to electric field for wave propagating in Z-direction. Two pass band poles and two zeros are obtained by perpendicular arrangement of meandered patterns on two sides of the substrate. Orthogonal arrangement of patterns ensure polarization symmetry (polarization insensitive) for Transverse Electric (TE) and Transverse Magnetic (TM) modes of exciting wave. Two pass band pole frequencies are positioned at 1.84 GHz and 4.53 GHz with low Insertion Losses (IL) of 0.67 dB and 1 dB, respectively. The lower and higher frequency bands have factional bandwidths of 41 % and 46 %, respectively. The transmission nulls occupy 2.8 GHz and 6.58 GHz frequencies. The structure is miniaturized to 0.032λ 0 × 0.032λ 0 dimensions with respect to lowest resonance residing at 1.83 GHz. The low IL at both pass bands is realized despite of using a lossy FR-4 material that can be improved to less than 0.5 dB at both the bands using less lossy materials such as F4BME or RO4003C. The proposed DPSFSS design is elaborated using Equivalent Circuit Model (ECM) and Surface Current Distribution (SCD). Measurements are performed on fabricated DPSFSS prototype and it is observed that the measured results coincide well with the simulated response. Angle stability of the DPSFSS is excellent and no unwanted resonances are observed at oblique angles upto 80° for dual polarizations of wave.

Growth and physical-chemical characterization of manganese oxide and graphene-manganese oxide films for potential applications in energy store devices

The need for progress in the development of energy supply devices such as batteries and large capacitors has led to the improvement and innovation of these devices so that they can store energy efficiently, and additionally, they must be small, light, with low production costs, and friendly to the environment. For these reasons, in this investigation results of the characterization of physical and chemical behaviors of graphene-manganese oxide and copper and manganese oxide-copper systems are studied. The graphene was synthesized through the electrochemical exfoliation technique and deposited as a film on common glass and silicon substrates via the spray technique, and over this film, Mn2O3 films were deposited through spin coating. The Raman results showed the presence of peaks D and G, located at 1534 and 1597 cm−1, respectively. XPS analysis demonstrated that the graphene is made up of three layers. TEM studies determined that the graphene is polycrystalline, and XRD established the manganese oxide coatings’ growth along the (222) and (440) planes of Mn2O3. The optical behavior indicated that the absorbance of the graphene-Mn2O3 system decreases the energy gap in 0.8 eV concerning Mn2O3 films. The voltage-current measurements suggest that the density current in the discharge process of the Mn2O3–Cu electrode system was improved approximately 3-fold with the graphene-Mn2O3–Cu electrode system. The obtained results conclude that the addition of graphene to manganese oxide coatings increases their electrochemical performance, so graphene-manganese oxide could be used in energy storage devices.

Electrochemical Exfoliation and Growth of Nickel–Cobalt Layered Double Hydroxides@Black Phosphorus Hetero‐Nanostructure Textiles for Robust Foldable Supercapacitors

AbstractAdvanced innovation of flexible electrode with adequate redox activity and stably mechanical endurance that promotes charges kinetic migration and faradaic storage is pivotal for textile‐based supercapacitors (T‐SCs). Herein, this study reports a high‐performance T‐SCs electrode based on nickel–cobalt layered double hydroxides@black phosphorus (NiCo‐LDHs@BP) on a conductive silk (c‐silk) textile (NiCo‐LDHs@BP/c‐silk). Under negative voltage‐induced electrochemical exfoliation, the Ni2+ and Co2+ are embedded into bulk BP framework to form exfoliated BP nanosheets, and the NiCo‐LDHs are in situ grown within the BP networks, generating 3D NiCo‐LDHs@BP hetero‐nanostructure. Significantly, the NiCo‐LDHs@BP exhibits a large space‐charge area, enhanced adsorption energy for OH− and accelerated charges transfer/storage as confirmed using density functional theory calculations. Additionally, the T‐SCs electrode is fabricated by loading the blended NiCo‐LDHs@BP, sericin, and carbon nanotubes on fibroin textile via a silk reconstruction strategy, producing large area production, superior mechanical flexibility, and impressive electrochemical performance. The resultant NiCo‐LDHs@BP/c‐silk electrode exhibits large specific capacitance of 1291.3 F g−1 and considerable rate capacity in 1 M KOH electrolyte. Furthermore, the flexible solid‐state asymmetric T‐SCs deliver high specific areal energy density of 279.6 µWh cm−2 and robust folding capability (85.6% capacitance retention after 5000 folding cycles), which successfully power wearable watch and heart rate meter devices.

Pinecone derived hierarchical carbon nanostructure as a transducer in a solid-state ion-selective electrode for in vivo analysis of calcium ion

Monitoring extracellular calcium ion (Ca2+) chemical signals in neurons is crucial for tracking physiological and pathological changes associated with brain diseases in live animals. Potentiometry based solid-state ion-selective electrodes (ISEs) with the assist of functional carbon nanomaterials as ideal solid-contact layer could realize the potential response for in vitro and in vivo analysis. Herein, we employ a kind of biomass derived porous carbon as a transducing layer to prompt efficient ion to electron transduction while stabilizes the potential drift. The eco-friendly porous carbon after activation (APB) displays a high specific area with inherit macropores, micropores, and large specific capacitance. When employed as transducer in ISEs, a stable potential response, minimized potential drift can be obtained. Benefiting from these excellent properties, a solid-state Ca2+ selective carbon fiber electrodes (CFEs) with a sandwich structure is constructed and employed for real time sensing of Ca2+ under electrical stimulation. This study presents a new approach to develop sustainable and versatile transducers in solid-state ISEs, a crucial way for in vivo sensing.

A novel separator material derived from discarded disposable medical mask waste for supercapacitor applications

ABSTRACT The coronavirus disease (COVID-19) pandemic outbreak occurring approximately 2019–2022 required everyone to wear a mask to reduce the number of transmissions of this virus; thus, the use of disposable medical masks has increased very sharply. As a result, the use of disposable medical masks produces a large amount of mask waste, which leads to negative effects on biosafety and the environment. To address this problem, in this work, for the first time, disposable medical mask waste was used as a separator material in supercapacitor devices. The aim of this work was to utilize discarded medical mask waste as a separator material in supercapacitor devices, and its performance was compared with that of eggshell membrane-based separators. The morphological structure of the separator materials revealed similar morphologies based on the SEM image. The electrochemical performance results showed large specific capacitances of 254 F g−1, 299 F g−1, and 205 F g−1 for YCCFs-MW1, YCCFs-MW2, and YCCFs-MW3, respectively. This work showed that disposable medical mask waste has huge potential for use as a separator in supercapacitor devices based on its electrochemical performance.

DBS−-doped polypyrrole/CNTs with 3D conductive architecture connected with MoS2 as symmetrical electrodes for boosted CDI capability

Molybdenum disulfide (MoS2), as an appealing Faradaic material for efficient capacitive deionization (CDI), is limited by unsatisfactory electrical conductivity, inferior removal rate, and restacking. Herein, we develop a CNT/PPy/MoS2 ternary composite using a robust 3D conductive interconnected structure CNT/PPy, constructed from multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy) doped with dodecyl benzene sulfonate (DBS-), as the growing substrate to mitigate the aggregation of MoS2 nanoflakes. In this design, CNT/PPy ameliorates the wettability of the composite, provides convenient movement pathways, a fast charge transport rate, and facilitates ions diffusion process. Moreover, reinforced dispersibility and enlarged interlayer spacing of MoS2 nanoflakes supply sufficient embedded sites for ion uptake and rapid transfer. Meanwhile, tight chemical coupling of Mo-N-C bonds can maintain the structural integrity of the composite electrode. Particularly, the symmetrical electrode configuration was established to address the kinetical unbalance of HCDI system. Consequently, the CNT/PPy/MoS2 displays a large specific capacitance of 160.83 F g−1 at 5 mV s−1, which is nearly 4.33 times that of MoS2 (37.17 F g−1). The optimized CNT/PPy/MoS2 cell achieves a maximum desalination capacity of 24.8 mg g−1, ultra-high deionization rate of 5.24 mg g−1 min−1, and superior capacity retention rate of 92.7% over 25 cycles. In addition, Na+ ions were captured by the joint action of cation-exchange of DBS--doped PPy, electrostatic adsorption of CNTs, and intercalation reaction of MoS2. The proposed composite structural design and electrode configuration should be a potential avenue to realize highly efficient deionization.

Computational insights into the electronic structure of functionalized monolayer hBN supercapacitor electrodes

In this study, we examined a collection of functionalized hBN monolayers’ electronic structure and quantum capacitance. Different ad-atom adsorption techniques have been used to functionalize the hBN monolayer. Density functional theory calculations are performed to precisely determine the electrical structure of an ad-atom doped hBN monolayer with a range of doping concentrations. The quantum capacitance of every functionalized system was then calculated. Above 500 μF/cm2, a noticeable quantum capacitance has been seen. Our calculations demonstrate that ad-atom doping at hollow position of hBN honeycomb lattice greatly increases the quantum capacitance of hBN monolayer. The microscopic cause of this system’s increased quantum capacitance has been investigated. Our DFT-based calculation shows that the system has a very large quantum capacitance due to the creation of new electronic states in the vicinity of the band edge and the Fermi level shift caused by the ad-atom adsorption.

Wiring surface loss of a superconducting transmon qubit

Quantum processors using superconducting qubits suffer from dielectric loss leading to noise and dissipation. Qubits are usually designed as large capacitor pads connected to a non-linear Josephson junction (or SQUID) by a superconducting thin metal wiring. Here, we report on finite-element simulation and experimental results confirming that more than 50% of surface loss in transmon qubits can originate from Josephson junctions wiring and can limit qubit relaxation time. We experimentally extracted dielectric loss tangents of qubit elements and showed that dominant surface loss of wiring can occur for real qubits designs. Finally, we experimentally demonstrate up to 20% improvement in qubit quality factor by wiring design optimization.

MOF-Mediated Construction of NiCoMn-LDH Nanoflakes Assembled Co(OH)F Nanorods for Improved Supercapacitive Performance.

The application of transition metal hydroxides has long been plagued by its poor conductivity and stability as well as severe aggregation tendency. In this paper, a novel hierarchical core-shell architecture, using an F-doped Co(OH)2 nanorod array (Co(OH)F) as the core and Mn/Ni co-doped Co(OH)2 nanosheets (NiCoMn-LDH) as the shell, was constructed via an MOF-mediated in situ generation method. The obtained Co(OH)F@ NiCoMn-LDH composites exhibited excellent supercapacitive performance with large specific capacitance as well as improved rate capability and long-term stability. The effect of the Ni/Mn ratio on the supercapacitive performance and energy storage kinetics was systematically investigated and the related mechanism was revealed.

Facile Solid-State Chemical Synthesis of CoMoO4 Nanorods for High-Performance Supercapacitors.

The development of electrode materials with excellent performance serves as the key for researchers to enhance the energy density of supercapacitors. Cobalt molybdate (CoMoO4) nanomaterials have been regarded as one of the most prospective electrode materials for supercapacitors due to their high theoretical capacitance and excellent electrical conductivity. In this paper, three kinds of CoMoO4 nanorods were prepared directly via simple and environmentally friendly solid-phase chemical reactions with solid inorganic salts as raw materials. According to X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) test results, different reagents had certain effects on the size and morphology of CoMoO4, and these affected its electrochemical performance. In particular, the samples prepared with Co(NO3)2·6H2O as raw material took on a more uniform micromorphology, with a better crystallinity. Simultaneously, electrochemical test results showed that the samples synthesized with Co(NO3)2·6H2O presented relatively good electrical conductivity and a large specific capacitance (177 F g-1). This may be due to the nitrates reacting more slowly during the reaction and the crystals having difficulty aggregating during growth. Therefore, the structure of the prepared CoMoO4 nanomaterial was more uniform, and it was resistant to collapse during the charging and discharging process; thus, the capacitor presents the best performance.

Stash: Flexible Energy Storage for Intermittent Sensors

Batteryless sensors promise a sustainable future for sensing, but they face significant challenges when storing and using environmental energy. Incoming energy can fluctuate unpredictably between periods of scarcity and abundance, and device performance depends on both incoming energy and how much a device can store. Existing batteryless devices have used fixed or run-time selectable front-end capacitor banks to meet the energy needs of different tasks. Neither approach adapts well to rapidly changing energy harvesting conditions, nor does it allow devices to store excess energy during times of abundance without sacrificing performance. This article presents Stash, a hardware back-end energy storage technique that allows batteryless devices to charge quickly and store excess energy when it is abundant, extending their operating time and carrying out additional tasks without compromising the main ones. Stash performs like a small capacitor device when small capacitors excel and like a large capacitor device when large capacitors excel, with no additional software complexity and negligible power overhead. We evaluate Stash using two applications—temperature sensing and wearable activity monitoring—under both synthetic solar energy and recorded solar and thermal traces from various human activities. Our results show that Stash increased sensor coverage by up to 15% under variable energy-harvesting conditions when compared to competitor configurations that used fixed small, large, and reconfigurable front-end energy storage.

Defect engineering of Cu2-xGaxO/PDINH nanomaterial for significantly improved photocatalytic antibacterial activities

The judicious engineering of defects and microstructure in novel photocatalysts is essential for optimizing their functional properties. This study focuses on the design of copper oxide (Cu2O)-based catalysts employing defect engineering and heterogeneous composition with perylene-3,4,9,10-tetracarboximide (PDINH) to enhance their photocatalytic antibacterial performance. Introducing transition metals such as gallium (Ga) into the Cu2O lattice serves to 1) generate Cu vacancies to accelerate reactive oxygen species (ROS) kinetics, 2) induce a small size effect in Cu2O nanoparticles to amplify photocatalytic activities, and 3) fine-tune electronic characteristics by modulating the electron density near the Fermi level and the d-band center. The defect engineering of doped Ga atoms and the p-n junction construction with PDINH resulted in a notable redshift of the light absorption edge of Cu2O. The optimized Cu2-xGaxO/PDINH (x=0.2) nanomaterials displayed superior photocatalytic antibacterial performance, achieving bacterial inhibition rates greater than 91% against Staphylococcus aureus and Pseudomonas aeruginosa. The nanomaterial also exhibited a large double-layer capacitance, elevated photocurrent density, and substantial ROS production. Cu1.8Ga0.2O/PDINH nanomaterial was a potent candidate for photocatalysis and environmentally friendly antibacterial treatments.

Power Quality Improvement of Micro Grid by Using DVR

Power quality is defined as the degree of voltage, current, frequency and waveform of power system under designed specification of the system. While transmitting the power from one end (generation) to another (load) utility has to face some power quality issues such as voltage sag, voltage swell, harmonics, inter-harmonics, voltage imbalance, voltage fluctuation, short duration voltage variation, long duration voltage variation, transient, power frequency variation, waveform distortion etc. These power quality issues directly effect on the efficiency of the power system and performance of the load equipment’s. Problems like voltage sag, voltage swell occurs due to sudden removal of large load from the system, energization of large capacitor bank or system fault like single-line-to-ground fault. These types of problems directly effect on equipment performance and accuracy, especially on sensitive equipment’s as computer, medical instruments, some electronic devices etc. To mitigate voltage sag, voltage swell problem in power system various devices are used such as DVR (dynamic voltage restorer) Key Words: Voltage sag, Voltage swell, Power quality, MATLAB simulation, Single-phase AC system, Single-phase AC load.

Voltage Detector Integrated Circuit as Versatile Toolbox for Charge Management of Thermally Chargeable Supercapacitor

AbstractInternet of Things (IoT) is crucial for a sustainable society from the viewpoints of optimization of energy consumption and using timing, thus aiding reduced CO2 emissions. Traditional power supply methods such as batteries are impractical for driving the trillions of sensors that future systems will likely utilize for collecting extensive environmental information. Thermoelectric power generators that enable direct heat‐to‐electricity energy conversion are considered a promising power supplying technology without maintenance because thermal energy is a ubiquitous energy source. This study develops a new class of thermoelectric modules using redox‐free electrolytes—‐thermally chargeable supercapacitor (TCS)—‐with extremely high thermoelectromotive force, generating over 2 V from a temperature difference of ≈65 °C without requiring a DC‐to‐DC converter. Additionally, using a voltage detector is demonstrated to be a versatile and efficient toolbox for the charge management of TCS. Optimization of the circuit comprising the TCS module with the ultrahigh open‐circuit voltage and voltage detector enables the automatic charging of a large capacitor, which intermittently powers different devices such as a beacon, LED, piezo speaker, and motor with the desired frequency. This approach represents a significant step toward sustainable energy in the context of low‐grade thermal energy harvesting and optimized energy consumption through IoT.