Unprecedented Voltage Research Articles

A voltage-decoupled Zn-Br2 flow battery for large-scale energy storage

The flow battery represents a highly promising energy storage technology for the large-scale utilization of environmentally friendly renewable energy sources. However, the increasing discharge power of rechargeable battery results in a higher charge voltage due to its coupling relationship in charge-discharge processes, intensifying the burden of renewable energy power systems. Herein, we proposed a voltage-decoupled Na+-conducting Zn-Br2 flow battery (Ud-Na-ZBFB). Within a pH-regulation strategy, both neutral Zn/Zn2+ and alkaline Zn/Zn(OH)42− negative redox couples are integrated into one device, so as to increase discharge voltage a 0.5 V theoretical increase while remains a low charge voltage. The proof-of-concept Ud-Na-ZBFB demonstrates an unprecedented voltage characteristic, achieving a discharge voltage of up to 2.18 V while maintaining a remarkably low charge voltage of 1.78 V at a current density of 20 mA cm−2. Benefiting from the high discharge voltage, the peak power density of Ud-Na-ZBFB reaches 580 mW cm−2, nearly twice higher than the traditional ZBFB. Besides, the Ud-Na-ZBFB cycling operates for 45 h with excellent stability and resilience. With the “cycle-to-stage” operational mode, battery state of Ud-Na-ZBFB can be completely recovered after a long-term operation stage with several cycles, which electrolyte utilization efficiency of one stage is up to 41 %. This work offers a brand-new utilization pattern for high-power rechargeable battery that possesses a great potential in energy storage application scenes.

Piezoelectric conductive electrospun nanocomposite PCL/Polyaniline/Barium Titanate scaffold for tissue engineering applications

Recent trends in tissue engineering technology have switched to electrical potentials generated through bioactive scaffolds regarding their appropriate effects on cell behaviors. Preparing a piezo-electrical stimuli scaffold with high electrical conductivity for bone and cartilage tissue regeneration is the ultimate goal of the present study. Here, Barium Titanate nanoparticles (BaTiO3 NPs) were used as piezoelectric material and highly conductive binary doped Polyaniline nanoparticles (PANI NPs) were synthesized by oxidative polymerization. Polycaprolactone (PCL) was applied as carrier substrate polymer and conductive spun nanofibrous scaffolds of PCL/PANI composites were prepared in two different amounts of PANI (3 and 5 wt.%). The conductivity of PCL/PANI nanofibers has been analyzed by standard four probes test. Based on the obtained results, the PCL/PANI5 (with 5 wt.% PANI) was selected due to the superior electrical conductivity of 8.06 × 10–4 s cm - 1. Moreover, the piezoelectric nanofibrous scaffolds of PCL/BT composite were electrospun in three different amounts of BT (20, 30, and 40 wt.%). To investigate the synergic effect of conductive PANI and piezoelectric BT, ternary nanocomposite scaffolds of PCL/PANI/BT were prepared using the dual jet electrospinning technique. The piezoelectric properties have been analyzed by determining the produced voltage. The morphological assessment, contact angle, mechanical test, and MTT assay have been conducted to evaluate other properties including biocompatibility of nanofibrous scaffolds. The PCL/PANI5/BT40 composite resulted in an unprecedented voltage of 1.9 Volt. SEM results confirm that BT NPs have been distributed and embedded inside PCL fibers quite appropriately. Also, the chosen scaffolds were homogeneously intertwined and possessed an average fiber diameter of 288 ± 180 nm, and a contact angle of 92 ± 7°, making it a desirable surface for cell attachment and protein interactions. Moreover, Young’s modulus, ultimate tensile stress, and elongation were obtained as 11 ± 1 MPa, 5 ± 0.6 MPa, and 109 ± 15% respectively. Obtained results assert the novel potential of piezo-electrical stimuli conductive nanocomposite scaffold for tissue engineering applications.

Analysis of interactions between regulated distribution transformers (RDT) and local voltage control Q(V) by means of the harmonic balance method

The increase of decentralized power generation in low voltage grids imposes new challenges on the conventional operating strategies for electrical grids, as power transmission used to predominantly pass from high voltage levels to low voltage levels. Distributed generation in low voltage grids lead to unprecedented voltage limit violations, which can efficiently be solved by implementing new control systems e.g. regulated distribution transformers (RDT) or local voltage control (e.g. Q(V)). Both correspond to closed-loop control systems and thus, are prone to stability issues and possible interactions with other control elements. Furthermore, the nonlinear characteristics of RDTs complicate the systems' stability analysis. This paper introduces the harmonic balance method as an approach to characterize the nonlinear behavior of an RDT and assess the system stability as well as possible interactions with other linear controllers in the electrical grid.

First test of a high voltage feedthrough for liquid Argon TPCs connected to a 300 kV power supply

Voltages above a hundred kilo-volt will be required to generate the drift field of future very large liquid Argon Time Projection Chambers. One of the most delicate component is the feedthrough whose role is to safely deliver the very high voltage to the cathode through the thick insulating walls of the cryostat without compromising the purity of the argon inside. This requires a feedthrough that is typically meters long and carefully designed to be vacuum tight and have small heat input. Furthermore, all materials should be carefully chosen to allow operation in cryogenic conditions. In addition, electric fields in liquid argon should be kept below a threshold to reduce risks of discharges. The combination of all above requirements represents significant challenges from the design and manufacturing perspective. In this paper, we report on the successful operation of a feedthrough satisfying all the above requirements. The details of the feedthrough design and its manufacturing steps are provided. Very high voltages up to unprecedented voltages of −300 kV could be applied during long periods repeatedly. A source of instability was observed, which was specific to the setup configuration which was used for the test and not due to the feedthrough itself.

High-Energy Density Redox Flow Lithium Battery with Unprecedented Voltage Efficiency

A redox flow lithium battery (RFLB) has decoupled energy storage and power generation units like a conventional redox flow battery, while it stores energy in solid materials by virtue of the unique redox targeting concept. Hence, it presents superior energy density and represents a promising approach for large-scale energy storage. In a RFLB, the potential difference between the redox shuttle molecules used in the same electrolyte normally brings about an intrinsic voltage hysteresis, resulting in a compromised voltage efficiency of the battery. Here we report a novel redox shuttle molecule pair to minimize the voltage hysteresis: anatase TiO2 is reduced by bis(pentamethylcyclopentadienyl)chromium (CrCp*2), while LixTiO2 is oxidized by cobaltocene (CoCp2). The potential difference between CoCp2 and CrCp*2 is only 0.15 V. A redox flow lithium battery is successfully demonstrated with an unprecedented voltage efficiency of 84%. The RFLB shows good cycling stability, and >90% Coulombic efficiency was demonst...

Interface-Located Photothermoelectric Effect of Organic Thermoelectric Materials in Enabling NIR Detection.

Organic photothermoelectric (PTE) materials are promising candidates for various photodetection applications. Herein, we report on poly[Cux(Cu-ett)]:PVDF, which is an excellent polymeric thermoelectric composite, possesses unprecedented PTE properties. The NIR light irradiation on the poly[Cu(x)(Cu-ett)]:PVDF film could induce obvious enhancement in Seebeck coefficient from 52 ± 1.5 to 79 ± 5.0 μV/K. By taking advantage of prominent photothermoelectric effect of poly[Cu(x)(Cu-ett)]:PVDF, an unprecedented voltage of 12 mV was obtained. This excellent performance enables its promising applications in electricity generation from solar energy and NIR detection to a wide range of light intensities ranging from 1.7 mW/cm(2) to 17 W/cm(2).

Low voltage extrinsic switching of ferroelectric δ-PVDF ultra-thin films

Non-volatile memories operating at low voltage are indispensable for flexible micro-electronic applications. To that end, ferroelectric δ-PVDF films were investigated as a function of layer thickness down to 10 nm ultra-thin films. Capacitors were fabricated using PEDOT:PSS as non-reactive electrode. Full polarization reversal was obtained at an unprecedented voltage below 5 V. The remanent polarization of 7 μC/cm2 and coercive field of 120 MV/m are independent of layer thickness, demonstrating that ferroelectric switching in δ-PVDF is extrinsic, dominated by inhomogeneous nucleation and growth. The ease of processing of δ-PVDF allowed to determine a lower limit of the critical ferroelectric thickness.

Thin film metal coated fiber optic hydrophone probe

Our purpose is to improve the performance sensitivity of a fiber sensor used as a fiber optic hydrophone probe (FOHP) by the addition of nanoscale thin film gold coating. The fiber is designed to provide a uniform and spatial averaging free response up to 100 MHz by etching down to an active diameter of approximately 9 mum. The performance sensitivity of straight cleaved (i.e., full size core and cladding) uncoated, tapered uncoated, and tapered thin film gold-coated fiber sensors was compared in the frequency range from 1.5 to 20 MHz in the presence of acoustic amplitude pressure levels as high as 6 MPa. An unprecedented voltage sensitivity of -245 dB relative to 1 V/muPa (560 mV/MPa) was measured for a thin film gold-coated FOHP by optimizing the gold coating thickness.

Wide-bandwidth multi-resolutional analysis of a surface-mounted PM synchronous machine

Advances in power semiconductor devices have led to inverters with unprecedented voltage edge rates. This has decreased inverter switching losses and enabled the use of increasingly higher switching frequencies. However, faster edge rates and higher switching frequencies increase electromagnetic compatibility (EMC) problems, machine insulation stress, bearing currents, and other aspects of system design. Typical computer simulations used to design and evaluate proposed electric drive systems cannot be used to predict these high-frequency effects. A wide-bandwidth multiresolutional analysis that allows designers to anticipate and quantify high-frequency effects is detailed in this paper. The approach is specifically applied to permanent magnet synchronous machine drives, and is validated experimentally.

Ferranti and the British Electrical Industry, 1864–1930 by J. F. Wilson

TECHNOLOGY AND CULTURE Book Reviews 169 Lewchuk’s book, based on detailed research in archival collections on both sides of the Atlantic, reflects new levels of sophistication in work on the motor industry. It will be of interest to readers in a range of disciplines from labor industry to the history of technology. In the detailed discussion of the problems of adapting production technol­ ogy to old institutions, Lewchuk’s work has a place alongside David Hounshell’s From the American System to Mass Production 1800—1932 (1984) and Michael Cusumano’s The Japanese Automobile Industry: Technology and Management at Nissan and Toyota (1985). Gerald T. Bloomfield Dr. Bloomfield is a professor of geography at the University of Guelph. His research interests include the historical geography of the automotive industry in Britain and North America. Ferranti and the British Electrical Industry, 1864—1930. By J. F. Wilson. Manchester and New York: Manchester University Press and St. Martin’s Press (distributor), 1988. Pp. ix+ 165; appendix, bibli­ ography, index. $39.95. The career of Sebastian Ziani de Ferranti (1864—1930), the ItalianBritish electrical engineer, contradicts the stereotypical image of the conservative British entrepreneur of the late Victorian and Edward­ ian periods. With no advanced scientific or engineering education, Ferranti quickly established an international reputation as an imagi­ native and bold electrical inventor who was far ahead of his contem­ poraries. Most of this reputation rests on the Deptford plant, a large central station built 8 miles from London on the other side of the Thames River (where land, coal, and water were inexpensive) in 1888—91. Ferranti designed the plant to supply alternating current to the city from four gigantic generators (10,000 horsepower each) through underground cables operating at the unprecedented voltage of 10,000 volts. Despite the plant’s many misfortunes—reduction of its service area by the Board of Trade in 1889, disruption of service and loss of customers caused by two fires in 1890, and the directors’ decision in 1891 not to complete the 10,000-hp generators—several historians have credited Deptford as the forerunner of modern electricity supply (transmission of high-voltage AC over long dis­ tances). Others, notably Thomas Hughes, have praised Ferranti for seeing the value of high-voltage AC but have criticized him for scaling up too quickly and for overlooking the advantages of polyphase over single-phase current (the former was better equipped at the time to provide electric power, as well as light, because of the recent invention of the induction motor). The extent of Ferranti’s technological “genius” is an important question for this new biography. One ofJ. F. Wilson’s main arguments 170 Book Reviews TECHNOLOGY AND CULTURE is that a restricted economic market and lack of financial support, not unfavorable laws or the lack of ingenuity, handicapped the British electrical industry in the late 19th century. The weak British economy thus constrained Ferranti’s inventive drive, which would have thrived in Germany or the United States. Paradoxically, Wilson also argues that much of the success which the Ferranti firm enjoyed before World War I was due to its executives’ reining in Ferranti’s inventive­ ness (e.g., persuading him to stop improving machines so they could be shipped out the door). Wilson admires Ferranti’s technical achieve­ ments and credits his technically led strategy for the firm’s success after World War I. But the real heroes of the book—published in a business history series—are the professional managers of the Ferranti company who introduced modern business methods that saved the firm—during its checkered history of fires and commercial failures— from the inept business decisions of its founder. Although better than the biography published by Ferranti’s daugh­ ter in the 1930s and more comprehensive than the booklet published by the London Science Museum, Wilson’s book is disappointing in many ways. Technical matters are described poorly, an unfortunate quality in a book that criticizes Hughes and others for their appraisal of Ferranti’s technical achievements. Wilson is not convincing on this score or in his attempt to explain the “failure” of British entrepre­ neurship in this period. Although based on research in the Ferranti...