Large-scale Devices Research Articles

A pioneering melamine foam-based electrode via facile synthesis as prospective direction for vanadium redox flow batteries

Among the large-scale energy storage devices, vanadium redox flow batteries (VRFBs) are one of the most promising candidates. Carbon felt and graphite felt have been widely adopted as electrodes, however, poor electrochemical activities and low specific surface areas have limited their rollout in the market. Herein, a brand new type of three-dimensional N, P co-doped/reduced graphene oxide (rGO) coated carbonized melamine foam electrode has been proposed to address the above critical issues. Three-dimensional interconnected network structure provides smooth channels for the electrolyte, rGO can further improve the conductivity of the electrode, and heteroatom doping provides additional reaction sites for conversion reactions. Material and electrochemical characterizations demonstrate that the novel electrode possesses a high specific surface area and excellent electrochemical properties. Benefiting from the elaborate design of the electrode structure, the corresponding VRFB is able to yield an energy efficiency of 74.14% at the current density of 300 mA cm−2, and long-term cycling stability is also proved more than 200 consecutive charge–discharge cycles at 200 mA cm−2 without significant decay. All these show that the derivative of melamine foam has enormous advantages and wide application prospects as novel excellent electrode material.

Hybrid Organic-Inorganic Perovskite Halide Materials for Photovoltaics towards Their Commercialization.

Hybrid organic–inorganic perovskite (HOIP) photovoltaics have emerged as a promising new technology for the next generation of photovoltaics since their first development 10 years ago, and show a high-power conversion efficiency (PCE) of about 29.3%. The power-conversion efficiency of these perovskite photovoltaics depends on the base materials used in their development, and methylammonium lead iodide is generally used as the main component. Perovskite materials have been further explored to increase their efficiency, as they are cheaper and easier to fabricate than silicon photovoltaics, which will lead to better commercialization. Even with these advantages, perovskite photovoltaics have a few drawbacks, such as their stability when in contact with heat and humidity, which pales in comparison to the 25-year stability of silicon, even with improvements are made when exploring new materials. To expand the benefits and address the drawbacks of perovskite photovoltaics, perovskite–silicon tandem photovoltaics have been suggested as a solution in the commercialization of perovskite photovoltaics. This tandem photovoltaic results in an increased PCE value by presenting a better total absorption wavelength for both perovskite and silicon photovoltaics. In this work, we summarized the advances in HOIP photovoltaics in the contact of new material developments, enhanced device fabrication, and innovative approaches to the commercialization of large-scale devices.

Damage Potential, Proppant-Transport Traits of High-Viscosity Friction Reducers

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199736, “High-Viscosity Friction Reducers: Potential for Fracture Damage and Impact of Brines on Proppant-Transport Capability,” by Barry Hlidek, SPE, and Robert Duenckel, SPE, Stim-Lab. The paper has not been peer reviewed. High-viscosity friction reducer (HVFR) fracturing fluids are used widely for unconventional reservoir development. HVFRs are easy to apply and can reduce chemical costs. The objective of the study described in the complete paper is to measure polymer cleanup in both propped and unpropped fractures using multiple methods. Additionally, the study compares rheological measurements in proppant-transport observations in brines using a large-scale slot-flow device. Potential for Formation Damage High-polymer-concentration crosslinked fracturing-fluid systems often have been supplanted by linear (i.e., noncrosslinked) guar systems of lower-polymer loading (e.g. 20 lbm/1,000 gal or less) or slickwater systems often thought to be nondamaging. Recently, HVFRs have been used regularly not only to provide friction reduction during pumping of the fracture stimulation but also to offer some degree of proppant transport. These usually are polyacrylamides with concentrations of 2–3 gal/1,000 gal, but concentrations may be as high as 6 gal/1,000 gal. The potential for damage from these HVFRs is the subject of the authors’ study. The complete paper discusses evaluation of proppant-pack damage in conventional reservoirs as well, but this synopsis will focus on evaluation of proppant-pack damage in unconventional reservoirs.

How to Get the Best Gas Separation Membranes from State-of-the-Art Glassy Polymers

Herein we focus on fundamental polymer science factors in membrane-based gas separation to open another chapter on this important topic. Realistically thinking about nanometer and angstrom scale matrix attributes that are translatable into higher performance thin glassy polymer asymmetric membrane layers in practical large-scale devices is crucial. Such thinking should be guided by expertise in both polymer and membrane communities to advance the state-of-the-art. Polymer structures, membrane morphologies, and effects of operating conditions are discussed here by using specific examples to illustrate key issues. Rubbery polymers are not the focus of this discussion since they lack diffusive discrimination for size-similar penetrants, which glassy polymers provide and make them the focus here. Four scalable subtopics guide necessary thinking: (i) plasticization, (ii) antiplasticization, (iii) dual-mode transport involving saturation of unrelaxed free volume, and (iv) nonuniform free volume and stress profiles in thin skin glassy polymer asymmetric or composite membranes. Using these subtopics in the context of macromolecular science, we discuss issues needed to expand the state-of-the-art in gas separation membranes.

Electrolyte Engineering Enables High Performance Zinc-Ion Batteries.

Zinc-ion batteries (ZIBs) feature high safety, low cost, environmental-friendliness, and promising electrochemical performance, and are therefore regarded as a potential technology to be applied in large-scale energy storage devices. However, ZIBs still face some critical challenges and bottlenecks. The electrolyte is an essential component of batteries and its properties affect the mass transport, energy storage mechanisms, reaction kinetics, and side reactions of ZIBs. The adjustment of electrolyte formulas usually has direct and obvious impacts on the overall output and performance. In this review, advanced electrolyte strategies are overviewed for optimizing the compatibility between cathode materials and electrolytes, inhibiting anode corrosion and dendrite growth, extending electrochemical stability windows, enabling wearable applications, and enhancing temperature tolerance. The underlying scientific mechanisms, electrolyte design principles, and recent progress are presented to provide a better understanding and inspiration to readers. In addition, a comprehensive perspective about electrolyte design and engineering for ZIBs is included.

Gate-tunable large-scale flexible monolayer MoS2 devices for photodetectors and optoelectronic synapses

Gate-tunable large-scale flexible monolayer MoS2 devices for photodetectors and optoelectronic synapses

Instrumented electromagnetic generator: Optimized performance by automatic self-adaptation of the generator structure

Electromagnetic generators are widely used to power both small-scale and large-scale devices. They are suitable to operate as self-powering technologies, allowing customizable upscaling and downscaling, ensuring low production and maintenance costs, and even able to integrate into hybrid solutions. As their architectures are well-suited to power a broad range of multifunctional devices, their performance optimization is a research topic of utmost importance. Their performance, strongly dependent on the frequency and amplitude of mechanical excitations and hysteretic behaviors, still needs to be improved. In this paper, a theoretical and experimental study is provided to demonstrate the effectiveness of a new concept of self-adaptive electromagnetic generator. An instrumented generator using a magnetic levitation architecture was implemented using a stepper motor, an accelerometer and a processing system. Self-adaptability was realized by changing the generator’s effective length and resonance frequency as a function of the mechanical excitation characteristics. Considering the power consumption of instrumentation, output power gains around 30% were achieved under conditions of harmonic inputs with time changing frequencies and amplitudes. These are very promising results that highlight the potential of self-adaptive energy harvesting technologies for opening new research directions towards the emerging of a new line of highly sophisticated autonomous generators.

Evidence for dual anions co-insertion in a transition metal chalcogenide cathode material NiSe2 for high-performance rechargeable aluminum-ion batteries

Rechargeable aluminum-ion batteries (RAIBs) are the subject of great interest owing to their attractive features like natural abundance, trivalent character, ultrahigh theoretical volumetric energy density and inherent safety, which endow RAIBs great prospect for large-scale energy storage devices. Nevertheless, the application of transition metal chalcogenide compounds as energy-dense cathode materials for RAIBs is currently hindered by their poor cycling stability and inadequate understanding of energy storage mechanisms. Here, we report dramatically enhanced aluminum storage performance from well-designed three-dimensional (3D) NiSe2 sponges wrapped with graphene oxide nanosheets (3D NiSe2 sponges@carbon composite). Electrochemical studies confirm that high capacity, superior rate capability and extraordinary cycling stability can be achieved from the prepared 3D NiSe2 sponges@carbon composite, rendering it a competitive cathode material for RAIBs. Moreover, combining comprehensive experimental measurements with systematic theoretical calculations, we show that dual anions co-insertion of AlCl4− and Cl− involved charge storage mechanism can be uncovered for the first time in NiSe2-based RAIBs. This new understanding of the aluminum storage mechanism provides chemical clues to further exploit the transition metal chalcogenide compounds electrode with substantial energy benefits.

Cheap, Large-Scale, and High-Performance Graphite-Based Flexible Thermoelectric Materials and Devices with Supernormal Industry Feasibility.

Flexible thermoelectric materials and devices show great potential to solve the energy crisis but still face great challenges of high cost, complex fabrication, and tedious postprocessing. Searching for abnormal thermoelectric materials with rapid and scale-up production can significantly accelerate their applications. Here, we develop superlarge 25 × 20 cm2 commercial graphite-produced composite films in batches, achieved by a standard 10 min industrial process. The high cost effectiveness (S2σ/cost) of 7250 μW g m-1 K-2 $-1 is absolutely ahead of that of the existing thermoelectric materials. The optimized composite film shows a high power factor of 94 μW m-1 K-2 at 150 °C, representing the optimal value of normal carbon materials so far. Furthermore, we design two types of flexible thermoelectric devices fabricated based on such a novel composite, which achieve an output open-circuit voltage of 3.70 mV using the human wrist as the heat source and 1.33 mV soaking in river water as the cold source. Our study provides distinguished inspiration to enrich flexible and cost-effective thermoelectric materials with industrial production.

Scalable Hamiltonian learning for large-scale out-of-equilibrium quantum dynamics

Large-scale quantum devices provide insights beyond the reach of classical simulations. However, for a reliable and verifiable quantum simulation, the building blocks of the quantum device require exquisite benchmarking. This benchmarking of large scale dynamical quantum systems represents a major challenge due to lack of efficient tools for their simulation. Here, we present a scalable algorithm based on neural networks for Hamiltonian tomography in out-of-equilibrium quantum systems. We illustrate our approach using a model for a forefront quantum simulation platform: ultracold atoms in optical lattices. Specifically, we show that our algorithm is able to reconstruct the Hamiltonian of an arbitrary size quasi-1D bosonic system using an accessible amount of experimental measurements. We are able to significantly increase the previously known parameter precision.

Science Translation During the COVID-19 Pandemic: An Academic-Public Health Partnership to Assess Capacity Limits in California.

On the basis of an extensive academic-public health partnership around COVID-19 response, we illustrate the challenge of science-policy translation by examining one of the most common nonpharmaceutical interventions: capacity limits. We study the implementation of a 20% capacity limit in retail facilities in the California Bay Area. Through a difference-in-differences analysis, we show that the intervention caused no material reduction in visits, using the same large-scale mobile device data on human movements (mobility data) originally used in the academic literature to support such limits. We show that the lack of effectiveness stems from a mismatch between the academic metric of capacity relative to peak visits and the policy metric of capacity relative to building code. The disconnect in metrics is amplified by mobility data losing predictive power after the early months of the pandemic, weakening the policy relevance of mobility-based interventions. Nonetheless, the data suggest that a better-grounded rationale for capacity limits is to reduce risk specifically during peak hours. To enhance the connection between science, policy, and public health in future times of crisis, we spell out 3 strategies: living models, coproduction, and shared metrics. (Am J Public Health. 2022;112(2):308-315. https://doi.org/10.2105/AJPH.2021.306576).

An IoT-Based Smart System with an MQTT Broker for Individual Patient Vital Sign Monitoring in Potential Emergency or Prehospital Applications.

Emergency care is a critical area of medicine whose outcomes are influenced by the time, availability, and accuracy of contextual information. The success of critical or emergency care is determined by the quality and accuracy of the information received during the emergency call and the data collected during emergency transportation. The Internet of Things (IoT) consists of many smart devices and components that communicate via their connection to the Internet, which is used to collect data with sensors that obtain personal health parameters. In the past, most health measurement systems were based on a single dedicated orientation, and few systems had multiple devices on the same platform. In addition to traditional health measurement technologies, most such systems use centralized data transmission, which means that health measurement data have become the exclusive intellectual asset of the system developer. Therefore, this study develops an IoT-based message-broker system that is deployed and demonstrated for five health devices: blood oxygen, blood pressure, forehead temperature, body temperature, and body weight sensors. A central controller accessed by radio-frequency identification (RFID) collects clients' health profiles on the cloud platform. All collected data can be quickly shared, analyzed, and visualized, and the health devices can be changed, added to, and removed reliably when the requirements change. Additionally, following the message queuing telemetry transport (MQTT) protocol, all devices can communicate with each other and be integrated into a higher-level health measurement standard (such as blood pressure plus weight or body temperature plus blood oxygen). We implement a smart healthcare monitoring system (SHMS) and verify its reliability. We use MQTT to establish an open communication format that other organizations can follow to perform individual patient vital sign monitoring in potential applications. The robustness and flexibility of this research can be verified through the addition of other systems. Through this structure, more large-scale health detection devices can be integrated into the method proposed in this research in the future. Personal RFID or health insurance cards can be used for personal services or in medical institutions, and the data can easily be shared through the mechanism of this research. Such information sharing will enable the utilization of medical resources to be maximized.

Halide chemical vapor deposition of 2D semiconducting atomically-thin crystals: From self-seeded to epitaxial growth

Atomically-thin crystals remain an epicenter of today's ongoing efforts of materials exploration for both fundamental knowledge and technological applications. We show that key modifications in the nucleation and growth steps lead to a controlled self-seeded growth of the monolayer transition metal dichalcogenide (TMDC) crystals and their lateral heterostructures via an halide chemical vapor deposition (HCVD) process which is a proven industrial scale and carbon-free synthesis technique for various material types. We present a general growth model with the limiting conditions on the nucleation density and crystal size of the 2D TMDCs grown in HCVD process. Furthermore, upon reduction of the self-seeded growth by a suitable surface pre-treatment, and by the modification of the nucleation step, epitaxial growth of monolayer TMDCs is also demonstrated using HCVD approach. The steady-state and time-resolved photoluminescence spectroscopic studies revealed the high optical and electronic quality of the as-grown 2D TMDCs semiconducting crystals. Field-effect transistor device characteristics of HCVD grown monolayer MoS2 using SiO2 gate dielectric shows an average mobility of 26 ± 7 cm2.V−1.s−1 and on-off ratio of ∼107, promising for large-scale device applications.

Large-Scale Inverse Design of a Planar On-Chip Mode Sorter

Spatial modes of light can be used as carriers of information in classical optical communication or as an alphabet in quantum optical communication. In order to exploit the spatial domain, it is required to (de)multiplex different modes from a shared input channel into different output ports. Mode sorters have been employed in free-space and fiber systems but to date have not been realized for planar guided waves. Here we present a general method for compact on-chip sorting of different planar beams with a micrometric footprint and nanometric thickness. The designs were generated using a linkage-tree-based genetic algorithm and were experimentally demonstrated on a surface plasmon polariton platform by sorting of Hermite–Gaussian beams. The method used here can be readily applied to optimize complex, large-scale optical devices involving beam propagation methods.

A crucial phase in plants - it's a gas, gas, gas!

A crucial phase in plants - it's a gas, gas, gas!

MQTT Protocol Extension for Real Time Location based Service

This paper introduces an extension of the MQTT protocol to reduce communication overhead in real-time location-based service system where mobile MQTT clients move and change their administrative district location frequently. The MQTT protocol was extended to handle UNSUBSCRIBE and SUBSCRIBE processing with a single step and the LBS server was revised to handle the extended protocol. Instead of directly processing SUBSCRIBE and UNSUBSCRIBE, mobile clients need to send their GPS location to the LBS server. LBS Server communicate with MQTT Broker to using extended protocol on behalf of each client. In an environment where large number of clients frequently move, the extended MQTT protocol can drastically reduce the number of messages between MQTT Broker and clients. This is mainly because clients do not need to issue SUBSCRIBE and UNSUBSCRIBE request to MQTT Broker. In addition, in contrast to our previous study where clients receive new administrative area name after sending its GPS location to LBS server, in this research, using extended MQTT protocol, mobile clients do not need to receive new administrative name even though they move across different district areas and as a result, the number of message exchanges can also be reduced. The LBS system applying the extended MQTT protocol can be used as a real-time location-based information service for large-scale mobile devices, such as real-time pedestrian population and vehicle traffic analysis, and location-based message delivery.

One-pot synthesis of nanosized MnO incorporated into N-doped carbon nanosheets for high performance lithium storage

As potential anode materials for lithium-ion batteries, transition metal oxides have been extensively investigated due to their high theoretical capacity. Nevertheless, how to address rapid capacity degradation and improve rate capability is still a big challenge. Herein, nanosized MnO incorporated into N-doped carbon nanosheets (MnO/NCN) was rationally designed by a facile one-pot salt-templated synthesis method. The nanosized MnO particles (around 20 nm) were powerfully anchored on the ultrathin N-doped carbon nanosheets to build a high-efficiency electrons/ions hybrid conductive framework. In addition, based on the stable interfacial interaction between MnO and N-doped carbon nanosheets, the MnO/NCN hybrid exhibits great structural stability, thus delivering high reversible lithium storage capacity (719 mA h g−1 at 0.1 A g−1) and superior stability (497 mA h g−1 at 1 A g−1 over 1000 cycles). Besides, the assembled lithium-ion capacitor with MnO/NCN anode exhibits excellent energy-power characteristics (142 W h kg−1 at 412 W kg−1). Such impressive lithium storage performance demonstrates that the MnO/NCN electrode is promising for large-scale energy storage devices.

Strategies towards Cost Reduction in the Manufacture of Printable Perovskite Solar Modules

Among different perovskite solar cell architectures, the carbon-based perovskite solar cell (C-PSC) is a promising candidate for upscaling and commercialization related to low-cost components and simple manufacturing methods. For upscaling a PV technology, three parameters must be considered, corresponding to efficiency, stability, and cost. While the efficiency and lifetime of perovskite technology are the focus of many research groups, the cost parameter is less studied. This work aims to provide information on the manufacturing cost of C-PSC based on experimental data in order to give the readers a panoramic overview of parameters influencing a fabrication process. To analyze the commercialization viability of this technology, we estimated the cost of raw materials and the manufacturing process for sub-modules using two different methods: registration and scribing. The fabrication cost of a sub-module fabricated using the scribing method with 7.9% efficiency was approximately 44% less than that of a device with 6.8% efficiency prepared using registration. We demonstrated that this is due to both the design parameters and performance. In addition, we showed a 51% cost reduction for registration devices by appropriate choice of solar cell components, fabrication steps, and equipment based on the existing infrastructures for the manufacturing of large-scale devices.

Bioinspired Topological Surfaces for Mitigating Water, Thermal and Energy Crises

ConspectusThe remarkable advances in technical and industrial fields have stimulated the world’s economic prosperity and population growth while also exacerbating the global water, thermal, and energy crises. To mitigate these crises, numerous large-scale devices have been constructed to harvest water, dissipate heat, and generate energy, yet they still encounter several bottlenecks, such as bulky size and climatic and/or geographic constraints. In contrast, miniature and portable water-based devices have demonstrated their tremendous potential in water harvesting and thermal/energy management due to the ubiquitous existence, large phase-change latent heat, and abundant kinetic energy of water. Owing to the strong dependence of their performance on the interfacial interactions between water and a surface, designing novel surface topology, in both physical and chemical aspects, is of practical importance to impart them with the ability to control the interfacial interaction/exchange among water, heat, and energy in an efficient, precise, and programmable manner.Developing novel, functional, and topological surfaces can involve learning from nature because many living organisms have evolved functional surface topologies to fundamentally tailor their interactions with liquids to survive in complicated and harsh environments. Although great progress has been made in bioinspired topological surfaces, two major bottlenecks consisting of a fundamental understanding and practical applications remain elusive. From the perspective of a fundamental understanding, the principles by which the surface topology of an organism controls the dynamic behavior of water droplets need to be deciphered comprehensively. From the perspective of practical applications, rationally designing surface topologies to achieve multifunctionality in industrial processes, especially in complex and harsh conditions, is of great importance. In this Account, we systematically review our recent progress in promoting bioinspired topological surfaces toward practical applications. We start with a fundamental investigation of various topological surfaces for rapid droplet bouncing facilitated by specific surface structures or a slippery liquid film. Subsequently, we introduce different surface topology designs for directional liquid transport. On the basis of these fundamental understandings, we further demonstrate their representative practical applications, including water harvesting, thermal management, and energy conversion. Finally, we offer a brief summary and perspectives on the development of novel bioinspired topological surfaces.

Data‐driven optimal scheduling for underground space based integrated hydrogen energy system

Integrated hydrogen energy systems (IHESs) have attracted extensive attention in mitigating climate problems. As a kind of large-scale hydrogen storage device, underground hydrogen storage (UHS) can be introduced into IHES to balance the seasonal energy mismatch, while bringing challenges to optimal operation of IHES due to the complex geological structure and uncertain hydrodynamics. To address this problem, a deep deterministic policy gradient (DDPG)-based optimal scheduling method for underground space based IHES is proposed. The energy management problem is formulated as a Markov decision process to characterize the interaction between environmental states and policy. Based on DDPG theory, the actor-critic structure is applied to approximate deterministic policy and actor-value function. Through policy iteration and actor-critic network training, the operation of UHS and other energy conversion devices can be adaptively optimised, which is driven by real-time response data instead of accurate system models. Finally, the effectiveness of the proposed optimal scheduling method and the benefits of underground space are verified through time-domain simulations.