High Output Current Research Articles

A hybrid nanogenerator based on wind energy harvesting for powering self-driven sensing systems

The increase in energy demand makes it urgent to explore green energy sources. And wind energy is one of the most promising renewable energy sources. In this paper, a rotating hybrid nanogenerator with a combination of a direct-current triboelectric nanogenerator (DC-TENG) and an electromagnetic generator (EMG) is designed; the design concept is to harvest wind energy. First, an optimized ternary DC-TENG is designed based on the ternary dielectric triboelectrification effect. A soft contact structure is designed, which can effectively increase the frictional area as well as reduce the frictional resistance. Then, by introducing the EMG unit, the output power of the device and the speed of charging the capacitor are increased. The high output voltage of the DC-TENG and the high output current of the EMG complement each other to produce excellent power output. At 180 rpm/min, the output power of DC-TENG and EMG can reach 1.78 mW and 215 mW, respectively. With a simple power management circuit design, the device is successfully implemented to power small electronic devices. By charging a suitable capacitor, the device can be used as a power supply to power the sensor. Together with the sensor and power management circuit, it forms a self-powered sensing system that can drive the sensor for continuous operation. This work provides a simple, convenient, and reliable design that offers new insights into energy harvesting in nature.

Design Considerations of Multi-Phase Buck DC-DC Converter

The main objective of this article is to propose a rational methodology for designing multi-phase step-down DC-DC converters, which can find applications both in engineering practice and in power electronics education. This study discusses the main types of losses in the multi-phase synchronous buck converter circuit (transistors’ conduction losses, high-side MOSFET’s switching losses, reverse recovery losses in the body diode, dead time losses, output capacitance losses in the MOSFETs, gate charge losses in MOSFETs, conduction losses in the inductor, and losses in the input and output capacitors) and provides analytical dependencies for their calculation. Based on the control examples for applications characterized by low voltage and high output current, the multi-phase buck converter’s output and input current ripples are analyzed and compared analytically and graphically (3D plots). Furthermore, graphical results of the converter efficiency at different numbers of phases (N = 2, 4, 6, 8, and 12) are presented. An analysis of the impact of various parameters on power losses is conducted. Thus, a discussion on assessing the factors influencing the selection of the number of phases in the multi-phase synchronous buck converter is presented. The proposed systematized approach, which offers a fast and accurate method for calculating power losses and overall converter efficiency, reduces the need for extensive preliminary computational procedures and achieves optimized solutions. Simulation results for investigating power losses in 8-phase multi-phase synchronous buck converters are also presented. The relative error between analytical and simulation results does not exceed 4%.

MXene Lubricated Tribovoltaic Nanogenerator with High Current Output and Long Lifetime

HighlightsSuccessfully solves the key issue of tribovoltaic nanogenerators (TVNGs) lifetime (90,000 cycles) and improves its output current density (754 mA m−2) simultaneously.Conductive polar liquid with MXene as additive is proposed as the dominant factor in enhancing the electrical output performance and durability of TVNG simultaneously.The mechanism of lubricated TVNG with enhanced output performance is explained from the perspective of solution polarity at the first time.Mxene solution exhibits universality in different types of semiconductor systems (Cu and P-type Si, and Cu and N-GaAs as material pairs).

Mechanoreceptor-inspired in-ear triboelectric sensor for unconstrained physiological monitoring and human–machine interaction

Recently emerged wearable electronics intended for human–machine interfaces and on-body healthy monitoring present undesired constraints on the human body despite considerable efforts to be flexible and more skin-compliant. In addition, the bulky back-end signal processing circuits hinder the miniaturization integration and commercialization of these wearable devices. Here, we propose a mechanoreceptor-inspired ear-worn triboelectric sensor which realizes unconstrained facial expression monitoring, such as eye and mouth motion, as well as demonstrating a hands-free typing system based solely on eye movements. The integration of an organic electrochemical transistor with low power consumption and high output current can amplify the current signal of the triboelectric sensor by at least 3 orders, enabling accurate extraction of minute pressure changes stimulated by pulse wave in the ear canal. In addition, the signal retention capability endowed by the organic electrochemical transistor enables an expanded control mode, which is demonstrated in an eye-triggered music playback control system. Our work presents the immense potential of ear-worn triboelectric sensor for unencumbered health monitoring and seamless human–machine interaction.

Fabrication and Characteristics of a Zinc Oxide Tunnel Effect Transistor with High Current Output

Fabrication and Characteristics of a Zinc Oxide Tunnel Effect Transistor with High Current Output

Nature-inspired surface for simultaneously harvesting water and triboelectric energy from ambient humidity using polymer brush coatings

Atmospheric water harvesting provides a promising, sustainable solution for alleviating the ever-growing water and energy crisis. Here, inspired by the Namib desert beetle, a wettability patterned surface was designed to simultaneously harvest water and triboelectric energy from ambient moisture. Indium tin oxide (ITO) conductive glass was coated by environmentally friendly perfluoropolyether (PFPE) polymer brushes to obtain a hydrophobic surface, decorated by hydrophilic patterns. The PFPE brushes enabled the droplet to slide down and served as the tribonegative material. The water and triboelectric energy harvesting performance of the hydrophilic-hydrophobic “patterned water and energy harvesting” (P-WEH) system was then investigated. In this regard, a water collection rate of 703 mg cm-2 h-1 was achieved when the P-WEH was placed within an artificial fog. The influence of pattern size and tilt angle, and their relationship with water droplet volume and speed on the triboelectric output, were measured. The effect of the water harvesting area on the output performance of the P-WEH was investigated. The P-WEH with an area of 100 cm2 and a tilt angle of 60° exhibited a high output current of 8.15 µA and a maximum output power of 3.35 µW. Finally, the P-WEH was integrated into a four-season greenhouse to demonstrate its application in reducing external water-energy consumption. This study presents insights into the design of simultaneous water and energy harvesting systems and may contribute to building a sustainable society.

High-density 2D hole gas in p-GaN/AlN/AlGaN on a silicon substrate with polarization-enhanced Mg ionization

Improving the hole concentration in p-GaN specimens has posed a major challenge due to the high activation energy of Mg doping in GaN. Recently, a delta doping technique for modulating the valence band and increasing the Mg ionization efficiency in GaN has been proposed. However, the memory effect of Mg in the reaction chamber greatly increases the difficulty of epitaxial growth; additionally, the Mg ionization efficiency remains too low. In this study, we demonstrate a novel p-GaN/AlN/AlGaN structure with an increased Mg ionization efficiency, from 5.16% to 14.22%, relative to the conventional p-GaN/AlGaN structure. The inserted AlN layer effectively modulates the valence band of p-GaN near the p-GaN/AlN interface and decreases the activation energy, as confirmed by density functional theory and the 1D Poisson–Schrodinger equation. Moreover, a high-performance p-channel GaN FinFET with a high output current of 114 mA/mm is fabricated, and the polarization-enhanced epitaxial layer shows great promise for next-generation digital ICs.

Plasma preparation of highly reactive Ag-Cu NPs anchored in N-PC as catalysts for Aluminum-air battery

Efficient, stable and economical catalysts play a crucial role in enhancing the kinetics of slow oxygen reduction reactions (ORR) in Aluminum-air batteries. Among the potential next-generation candidates, Ag catalysts are promising due to their high activity and low cost, but weaker oxygen adsorption has hindered industrialization. To address this bottleneck, Ag-alloying has emerged as a principal strategy. In this work, we successfully prepared Ag-Cu nanoparticles (NPs) with a rich eutectic phase and uniform dispersion structure using plasma evaporation. The increased solid solution of Ag and Cu led to changes in the electronic structure, resulting in an upward shift of the d-band center, which significantly improved oxygen adsorption. The combination of Ag and Cu in the NPs synergistically enhanced the adsorption of Ag and the desorption of Cu. Density functional theory (DFT) calculations revealed that Ag-Cu25 NPs exhibited the smallest limiting reaction barrier, leading to increased ORR activity. To further optimize the catalyst's performance, we utilized N-doped porous nanocarbon (N-PC) with high electrical conductivity and abundant mesoporous channels as the support for the Ag-Cu NPs. The N-PC support provided optimal mass transfer carriers for the highly active Ag-Cu25 NPs. As a result, the Ag-Cu25/NPC catalyst displayed excellent ORR activity in alkaline media, with a half-wave potential (E1/2) of 0.82 V. Furthermore, the Al-air battery incorporating the Ag-Cu25/NPC catalyst exhibited outstanding electrochemical performance. It demonstrated high open-circuit voltages of 1.89 V and remarkable power densities of 193 mW cm−2. The battery also sustained a high current output and maintained a stable high voltage for 120 hours under mechanical charging, showcasing its significant potential for practical applications.

Dynamic Perovskite Homojunction Based Light‐Assisted, Direct Current Tribovoltaic Nanogenerators

AbstractTribovoltaic nanogenerators (TVNG) are an emerging energy technology featuring high direct current density and continuous power output. Recently, a new kind of perovskite/metal Schottky‐based TVNG has attracted increasing attention, which can co‐harvest mechanical and solar energy to dramatically improve the DC output performance. However, the instability of the perovskite‐metal interface and unnecessary carrier recombination loss limit its practicability. Here, a novel light‐assisted TVNG based on a dynamic N‐type perovskite/P‐type perovskite homojunction is developed. The homojunction design can ensure stable interface contact, and contributes to forming a strong built‐in electric field to promote efficient carrier separation/extraction and decrease interfacial charge recombination loss. In addition, the innovative design of the dual perovskite functional electrode maximizes its photovoltaic characteristics and further facilitates the excitation of more charges based on tribo‐photovoltaic coupling effects. Eventually, the output voltage and current of dynamic perovskite homojunction can boost up to ≈8.72 V and ≈30.84 µA under illumination, showing outstanding performance among the state‐of‐the‐art perovskite‐based TVNGs. These findings demonstrate the great potential of perovskite materials in generating DC power and present a feasible strategy to construct efficient, multifunctional TVNGs.

Research on High Power Fuel Cell DC-DC Based on SiC Devices

With the increasing shortage of traditional energy resources, new energy resources such as fuel cells are widely used. However, the front-end output voltage of new energy power generation systems such as fuel cells is low, which cannot directly supply power to the load. Therefore, an efficient DC converter with a high boost ratio is needed to raise the voltage to the required level. The staggered parallel DC boost converter has the characteristics of small input current ripple and high voltage gain, which is very suitable for low voltage and high current input and high voltage output. Compared with Si Mosfet, SiC Mosfet has better on-state and on-switch characteristics. In this paper, the requirements of fuel cells in DC-DC are analyzed, the characteristics and applications of SiC devices are introduced, and the topology and working principle of DC-DC are studied. By comparing the topology of isolated DC-DC and non-isolated DC-DC, the staggered Boost circuit topology is selected. The advantages and working state of multiple staggered parallel circuits are studied in detail.

Biomimetic Aerogel with Aligned Porous Structures from Ice Templating for Water Evaporation‐Induced Electricity Generation

AbstractWater evaporation is a ubiquitous natural process for collecting thermal energy from the environment. Carbon nanomaterial‐based aerogels are good candidates for use as hydroelectric generators (HEGs), permitting substantial interaction with water through electronic coupling, and have been considered for application in evaporation‐induced electricity generation. However, the water transport and electricity generation ability of the aerogels are affected by their pore structures. Inspired by the directional transport of the water vessel elements of the xylem, a biomimetic partially reduced graphene oxide aerogel (prGO) with an aligned porous structure is prepared, assisted by directional ice templating. The as‐prepared prGO aerogel presents a high capillary water transport rate and can efficiently transport water to the top, which is the basis for efficient current generation. This biomimetic prGO is scalable, providing an avenue for assembling other low‐dimensional carbon materials into high current output HEGs.

A new low voltage low power fully differential CMOS class AB current output stage with unique current drive capability

ABSTRACT This paper presents a novel low-voltage low power fully differential class AB current output stage with high linearity and unique current drive capability. The proposed circuit is based on a simple and efficient structure to obtain high linearity by minimising the channel length modulation effect and also avoids cascade structure to act best in low-voltage applications. Giving the complete analyses and equations of the circuit, its properties are verified by Cadence using TSMC 0.18 µm CMOS parameters. In order to study its performance at the presence of non-idealities, Pre-layout and Post-layout both plus Monte–Carlo simulations are also performed. Under±0.9 V supply and 35 µA output bias current, it can deliver the ever high output current of ±350 mA with THD of −49 dB and output impedance of 2.8 MΩ, which leads to a unique high current drive ratio (Ioutmax/Ibias) of 10,000 and low consumed power of 150 µw in pre-layout simulation. In post-layout plus Monte–Carlo simulation, the results will be as ±320 mA output current, −42 dB THD, 2.2 MΩ output impedance, 40 µA DC current of the output branch, 8000 current drive ratio and 160 µw consumed power. These remarkable results prove the proposed novel COS not only as the unique one in the world but Longley ahead of the yet second rank COS by some unbeatable ratios as 11300×,14×,4× and3× in F T , I outmax , (Ioutmax/power), and current drive, respectively, that promise to keep it as the lead one for many years in low-voltage/power ultra-high current applications.

High‐Performance Integrated Iontronic Circuits Based on Single Nano/Microchannels

Recently, artificial channel-based ionic diodes and transistors are extensively studied to mimic biological systems. Most of them are constructed vertically and are challenging to be further integrated. Several examples of ionic circuits with horizontal ionic diodes are reported. However, they generally require nanoscale channel sizes to meet the demand for ion-selectivity, resulting in low current output and restricting potential applications. In this paper, a novel ionic diode is developed based on multiple-layer polyelectrolyte nanochannel network membranes. Both bipolar and unipolar ionic diodes can be achieved by simply switching the modification solution. Ionic diodes with a high rectification ratio of ≈226 are achieved in single channels with the largest channel size of 2.5µm. This design can significantly reduce the channel size requirement and improve the output current level of ionic devices. The high-performance ionic diode with a horizontal structure enables the integration of advanced iontronic circuits. Ionic transistors, logic gates, and rectifiers are fabricated on a single chip and demonstrated for current rectification. Furthermore, the excellent current rectification ratio and the high output current of the on-chip ionic devices highlight the promise of the ionic diode as a component of complex iontronic systems for practical applications.

Research on DC Power Supply for Electrolytic Water to Hydrogen Based on Renewable Energy

Hydrogen production from electrolytic water based on Renewable Energy has been found as a vital method for the local consumption of new energy and the utilization of hydrogen energy. In this paper, the hydrogen production power supply matching the working characteristics of electrolytic water production was investigated. Through the analysis of the correlation between the electrolysis current and temperature of the proton exchange membrane electrolyzer and the electrolyzer port voltage, energy efficiency, and hydrogen production speed, it was concluded that the hydrogen production power supply should be characterized by low output current ripple, high output current, and wide range voltage output. To meet the requirements of the system of hydrogen production from electrolytic water based on new energy, a hydrogen production power supply scheme was proposed based on Y which is the type three, is the phase staggered parallel LLC topology. In the proposed scheme, the cavity with three is the phase staggered parallel output is resonated to meet the operating characteristics (high current and low ripple) of the electrolyzer, and pulse frequency control is adopted to achieve resonant soft in the switching operation and increase conversion efficiency. Lastly, a simulation model and a 6kW experimental prototype were built to verify the rationality and feasibility of the proposed scheme.

Development of Phase-Shift Full-Bridge Converter With Integrated Winding Planar Two-Transformer for LDC

This study proposes a new phase-shift full-bridge (PSFB) converter with an integrated winding planar two-transformer for a low-voltage dc–dc converter (LDC). An LDC is a dc–dc converter that supplies power to a 12-V auxiliary battery (A_BAT) and loads from the main battery (M_BAT) of electric vehicles (EVs), used in low-voltage and high-current output applications. PSFB converter is widely used as a suitable topology for such systems. In order to improve the power density, the integrated planar magnetics is designed in the proposed PSFB converter. Furthermore, the size of the transformer is optimized considering the footprint and core loss of components. To confirm the validity of the proposed converter, a 2.1-kW prototype LDC with an input voltage range of 400–800 V and an output voltage of 14 V is analyzed, and the operating characteristics are described. The proposed converter achieves a maximum efficiency of 95.4% and a power density of 5.2 kW/L.

High-Output Wearable Flow Ring-Based Triboelectric Nanogenerator via Opposite Charging Intermediate Layer

Triboelectric nanogenerator (TENG) is one of the emerging energy harvesting technologies with the potential to be an alternative energy source. Owing to the various advantages of TENG, such as low cost, simple design, and high applicability, several researchers reported wearable TENG devices that can power electronics by harvesting human motion. However, as the human body has limited movement, the existing wearable TENG devices can only generate low power to turn on the electronics. In this study, a flow ring-based TENG (FR-TENG) is fabricated, which can be applied to wearable devices to generate high voltage and current output by including an opposite charging intermediate layer. By the simulation and experimental results, FR-TENG is optimized to generate a high output, that is, peak open-circuit voltage and closed-circuit current of up to 1020 V and 260 mA, respectively, owing to the electrostatic discharge. By these results, sleeve-type wearable FR-TENG is fabricated which can effectively harvest energy from arm movement. The sleeve-type FR-TENG can generate a high output owing to the working mechanism of FR-TENG; the high output was used to turn on 200 LEDs.

A triboelectric nanogenerator powered piezoresistive strain sensing technique insensitive to output variations

With the increasing trend of self-powered sensing in the era of Internet of Things (IoTs), triboelectric nanogenerator (TENG) sensors have attracted great attention due to their high efficiency, versatile configuration, and low cost. However, because of their inherent variation of outputs due to changing environmental conditions, the output magnitude of TENGs cannot be used directly as the primary sensing signal in practical scenario. To address this issue, herein a new method of extracting sensing signal is proposed that is independent of TENG output variations. The core idea is to split the output current of TENG into two parallel branches containing a piezoresistive strain sensor and reference resistors, respectively. The ratio of the currents in the two branches can be used to accurately determine the applied strain because the ratio is uniquely dependent on the resistance of the piezoresistive sensor and is insensitive to the TENG output magnitude, thus eliminating the effect of output variation on the sensing performance. As demonstrated in this work, a TENG can be used as the power source to activate piezoresistive sensors without knowing its output characteristics, although higher current outputs are preferred to minimise error from noise. This new method provides a new self-powered sensing solution that is invariant to output vairations due to changing environments.

Traceability Technology of DC Electric Energy Metering for On-Site Inspection of Chargers

The on-site inspection of high-power DC chargers results in new DC high-current measurement and DC energy traceability system requirements. This paper studies the traceability technology of electric energy value for automotive high-power DC chargers, including: (1) the traceability method of the built-in DC energy meter and shunt of the charger; (2) precision DC high current and small precision DC voltage output and measurement technology. This paper designs a 0.1 mA~600 A DC high current measurement system and proposes a 0.005 level DC power measurement traceability system. The uncertainty evaluation experiment of the DC power measurement calibration system and the high-power DC charger’s on-site calibration experiment results verify the method’s effectiveness and feasibility in this paper. The experimental results show that the combined standard uncertainty of the DC power metering verification system can be 0.0451%.

AlN micro-honeycomb reinforced stearic acid-based phase-change composites with high thermal conductivity for solar-thermal-electric conversion

The designed solar-thermal-electric device using the as-prepared MH-AlN/SA composite presents a high output voltage and current of 409 mV and 110.8 mA, respectively. Its peak output power density is high up to 113.3 W m−2.

Designing High Interfacial Conduction beyond Bulk via Engineering the Semiconductor-Ionic Heterostructure CeO2-δ/BaZr0.8Y0.2O3 for Superior Proton Conductive Fuel Cell and Water Electrolysis Applications.

Proton ceramic fuel cells (PCFCs) are an emerging clean energy technology; however, a key challenge persists in improving the electrolyte proton conductivity, e.g., around 10-3-10-2 S cm-1 at 600 °C for the well-known BaZr0.8Y0.2O3 (BZY), that is far below the required 0.1 S cm-1. Herein, we report an approach for tuning BZY from low bulk to high interfacial conduction by introducing a semiconductor CeO2-δ forming a semiconductor-ionic heterostructure CeO2-δ/BZY. The interfacial conduction was identified by a significantly higher conductivity obtained from the BZY grain boundary than that of the bulk and a further improvement from the CeO2-δ/BZY which achieved a remarkably high proton conductivity of 0.23 S cm-1. This enabled a high peak power of 845 mW cm-2 at 520 °C from a PCFC using the CeO2-δ/BZY as the electrolyte, in strong contrast to the BZY bulk conduction electrolyte with only 229 mW cm-2. Furthermore, the CeO2-δ/BZY fuel cell was operated under water electrolysis mode, exhibiting a very high current density output of 3.2 A cm-2 corresponding to a high H2 production rate, under 2.0 V at 520 °C. The band structure and a built-in-field-assisted proton transport mechanism have been proposed and explained. This work demonstrates an efficient way of tuning the electrolyte from low bulk to high interfacial proton conduction to attain sufficient conductivity required for PCFCs, electrolyzers, and other advanced electrochemical energy technologies.