Material Loss Research Articles

An Electrochemically Rechargeable Fuel for Continuous Operation of Electric Aircraft and Vehicles

Aviation and long-distance transport represent more than 6% of global CO2 emissions, but electrifying these fleets requires significant improvements in battery specific energy and power. Regional and narrow-body all-electric aircraft require 600-1,000 Wh kg-1 while mass-produced rechargeable batteries have energy densities below 300 Wh kg-1. Furthermore, batteries should be able to recharge instantly to near-continuously operate the machines they power and offset their high sunk costs, yet fully charging current batteries still takes 1-16 hours.Overcoming these technical bottlenecks requires entirely new approaches for powering electric vehicles that go beyond the pioneering intercalation materials that have dominated modern advances in batteries. For example, there are many energy-dense materials that can improve battery specific energy but do not work well in an intercalation battery architecture, especially small molecules such as organic compounds, organosulfurs, halides, and gases. Batteries with energy-dense small molecules suffer from active material loss by dissolution, irreversible reactions due to material crossover between electrodes, slow ion transport in the bulk material, and the use of excessive carbon to provide electronic conduction. These challenges cause current batteries to fall short of their high theoretical energy and power densities and suffer from poor reversibility and slow recharging.In this talk, we explore the potential for electrochemical fuels that are filled with energy-dense small molecules that can be electrically discharged in a battery cell, not a fuel cell, at the high rates needed for electric aircraft, and can be ejected from the vehicle and recharged in an external electrochemical cell so that new fuel can be rapidly filled into the vehicle for continuous operation.Our solution uses CH3S3CH3 small molecules stored in a supporting electrolyte as a catholyte paired with Li metal anodes, which we discharge in our extractor cell. The active material ratio in the catholyte is 65-80 wt.% to maximize cell specific energy. The discharge reaction occurs on an engineered porous current collector and the products are made soluble in the catholyte, which is critical to removing them for recycling and recharging. The liquid-to-liquid conversion enables fast kinetics, minimal polarization, promotes ion, electron, and mass transport and enables full conversion of the small molecules, which has been challenging in prior work.We demonstrate this concept in a toy robot dog and a commercial DJI quadrotor helicopter. A 10.4 Ah extractor cell provided up to 192 A kg-1 and achieved a specific energy of up to 850 Wh kg-1 (counting the full cell mass), which doubled the flight time of the Li-ion battery powered helicopter from 20 to 41 minutes. The fuel was mechanically recharged in 77 seconds, so that multiple rapid refills allowed a helicopter to operate for 23 hours in a 24-hour period. The fuel had a 3.2-year storage life and delivered 98% of its room temperature capacity at -20°C. Different from the fuels used in engines and fuel cells, the discharged liquid is rechargeable (99.97% chemical efficiency) with electrical input and the regenerated Li and catholyte can be used again in the stomach in what we refer to as a mechagenic cycle. This recycling makes the stomach more cost-efficient than batteries and gasoline after 41 flights in an electric aircraft. We also demonstrate fuels that have up to 1,447 Wh kg-1 or are completely aqueous for fire-safe applications. Overall, the use of abundant small molecules as electrochemical fuels could lead to a more sustainable and better performing energy cycle than current batteries. Figure caption: A sustainable energy cycle based on electrochemically rechargeable fuels. a, Envisioned mechagenic energy cycle for electric vehicles and robots that are rapidly refilled and return the discharged fuels to a recycler where it is converted back to a charged catholyte and metal using sustainable electricity. b, Photographs of a DJI Mini 2 helicopter powered by an extractor cell (a) and the recorded flight time compared to its factory-pack Li-ion battery (b). The fuel-powered helicopter had a 41-minute flight time, which is two times longer than the helicopter with the factory-pack Li-ion battery. c, The conversion of CH3S3CH3 monitored by 1H NMR. d, Voltage profile of the extractor cell operated at room temperature and -20°C. e, The voltage profile of the catholyte stored after 3.2 years. f, Rate performance of the extractor cell. With current densities of 32 to 192 A kg-1, the cell delivered at least 1 V output. g, A recycler separated by a LiSICON solid electrolyte plate. The two split chambers were filled with a CNT foam and a liquid electrolyte, respectively, to recycle the catholyte and Li metal at high efficiency. Figure 1

Shining Light on New Additives for Lithium Sulfur Batteries through Polysulfide Shuttle Tracking Operando Optical Fluorescence Microscopy

Lithium Sulfur (Li-S) batteries are uniquely poised to provide exciting new opportunities in the field of energy storage, possessing an impressive theoretical gravimetric specific capacity an order of magnitude greater than current lithium-ion batteries (1672 mA h g-1), and energy density over 5 times higher (2567 Wh kg-1), while also using far safer and more sustainable materials.However, their wilder proliferation and commercialisation suffers heavily from the polysulfide shuttle effect, where the lithium polysulfide intermediates generated at the cathode during the conversion mechanism of Li-S operation dissolve into the battery electrolyte and diffuse towards the lithium metal anode. This leads to parasitic reactions between the polysulfides and the anode, causing rapid cell degradation from active material loss, degradation of the anode solid electrolyte interface (SEI), and subsequent rapid dendrite formation. The shuttle effect is a primary mechanism of cell failure, and as such, most research into Li-S focuses on its mitigation. Current methods of characterizing the shuttle effect provide limited detail or are overly time consuming, so more robust characterization methods are required to further understand the distribution, dynamics, and degree of polysulfide transport.Here, the newly established Optical Fluorescence Microscopy (OFM) technique, for visualising the spatial distribution of polysulfides within the Li-S electrolyte and through sufficiently large cathode pores during operando cycling, is utilised for facile assessment of the efficacy of a variety of additives to Li-S batteries in reducing the polysulfide shuttle effect. Using a polysulfide sensitive fluorescent dye, established to be inert to both the components of a Li-S battery and the additives, the intermediate polysulfides formed throughout cycling can be made to fluoresce, and thus directly visualised. The correlation between fluorescence intensity and polysulfide concentration is also linear when below the linear concentration range of the dye, allowing for polysulfide concentration to be spatially quantified through use of a calibration curve. This enables direct observation of the kinetics of sulfur dissolution and the subsequent diffusion towards the anode and dendrite formation, and thus measurement of the efficacy of steps taken to prevent this.The effects of various additives are elucidated using this method – including the standard LiNO3 additive in sacrificially protecting the lithium anode through SEI formation, as well as novel fibroin-based additives trapping polysulfides within the cathode. Further, the total lack of solubilised intermediate polysulfides within the electrolyte potentially granted by a quasi-solid-state Li-S morphology is assessed through OFM. As is the impact of catalytic additives on the kinetics of the Li-S conversion mechanism, through reduction in the time polysulfides spend in the solubilised state. With OFM, one can directly and conveniently assess the real-time spatial distribution, dynamics, and degree of polysulfide transport in a cycling Li-S cell far faster and significantly easier then would be possible with other methods, and with a very robust dataset. OFM is thus an ideal platform for the development of polysulfide shuttle mitigation strategies, allowing rapid iteration of mitigation methods such as new additives or cathode morphologies. It has the potential for a widespread impact in the field of Li-S batteries, in both industry and academia, through collaboration with and usage by other researchers developing shuttle mitigation techniques. Figure 1

Deconvolved First Cycle Capacity Loss Mechanisms in All-Solid-State Batteries

Deconvolved First Cycle Capacity Loss Mechanisms in All-Solid-State Batteries All-solid-state batteries (SSBs) fail to compete with their traditional lithium-ion battery (LIB) counterparts due to severe capacity loss in their first cycle. While the key contributors to capacity loss have been identified, it remains unknown the relative contribution of each loss mechanism due to solid electrolyte (SE) redox and worsening kinetics which obscure the measure of capacity. For the chemically abundant sulfur-based composite electrodes in particular, these parallel processes present a formidable challenge to addressing first cycle Coulombic inefficiency.1 Using near-equilibrium electrochemical and X-ray techniques, we demonstrate a full accounting of the sources of capacity loss within our argyrodite SE (Li5PS6Cl) | uncoated Li(Ni0.5Mn0.3Co0.2)O2 (NMC) | carbon composite cathode. By modifying the components of the composite electrode, we differentiate between electrolyte redox at the electronic conductor (current collector + carbon)|SE and NMC|SE interfaces. Using these cell formats we investigate the persistence of electronic conductor interfacial redox across many cycles, as well as the impact of self-discharge on long-term cycling behavior. By modifying the cycling window, we also investigate sluggish discharge kinetics of cathode and oxidation reversibility. Using operando XRD, we compare LIBs and SSBs to track cathode redox throughout cycling, enabling us to differentiate and quantify sources of capacity loss. These findings highlight the need to address overlooked sources of resistance and active material loss in SSBs which are not mitigated by cathode coating solutions.[1] Janek, J., Zeier, W.G. Challenges in speeding up solid-state battery development. Nat Energy 8, 230–240 (2023).

Selective Etching of SiO2 over Si3N4 through Varying the Concentration of Fluorine Species

Silicon dioxide (SiO2) and silicon nitride (Si3N4) are widely used as an insulating layer to separate interconnection, due to the characteristic of their wide band gap. As the feature size of semiconductors has been continuously decreasing and their structures have become more complex recent years, SiO2 as an insulating layer is reaching its limit. One of the ways to overcome this limitation, next generation 3D structure semiconductors are developed. In order to manufacture these kinds of devices, a removal of SiO2 is required, however, as both SiO2 and Si3N4 layers are revealed, the highly selective SiO2 etching process over Si3N4 is needed. If the Si3N4 layers were etched during the SiO2 layer etching process, the Si3N4 layer could not be function as an insulating layer and an etch stop layer. As an etchant for the SiO2 layer, hydrofluoric acid (HF) and ammonium fluoride (NH4F) combining solution is mainly used. However, it is known that HF solution also causes the material loss of the Si3N4 layers. Therefore, the study of etching behaviors of SiO2 and Si3N4 in HF solution is needed. In HF solutions, main etching species of SiO2 and Si3N4 exists as fluorine species. The concentration of these fluorine species depends on various conditions, such as pH of the solution or the composition of HF and NH4F. Therefore, the dependence of SiO2 and Si3N4 etching rates on the conditions of HF solutions were investigated.To investigate the etching rates of SiO2 and Si3N4, the blanket SiO2 and Si3N4 wafer in which deposited on Si wafer by the low-pressured chemical vapor deposition method were used, respectively. A patterned SiO2/Si3N4 multi-stack structures were fabricated by plasma-enhanced chemical vapor deposition, to verify whether SiO2 was selectively etched over Si3N4 in HF solution. The HF solutions were prepared by adding various concentrations of HF to deionized water and NH4F was added in some cases. The pH of the HF solution was controlled by adding hydrochloric acid or ammonium hydroxide. The temperature maintained at 25 °C during the etching processes using a water bath. The blanket SiO2 and Si3N4 wafers were immersed in these solutions for 3 and 60 mins, respectively. The etching depth of the SiO2 and Si3N4 films was measured by spectroscopic ellipsometry. The morphology of patterned SiO2/Si3N4 multi-stack structures after etching process was observed using field-emission scanning electron microscopy (FE-SEM). The pH and the concentrations of each fluorine species of the prepared HF solutions were calculated based on the equilibrium constants, molar balance, and charge balance.To obtain the HF solution with the high SiO2 etching selectivity over Si3N4, blanket SiO2 and Si3N4 wafers were etched under various pH and initial concentrations of HF solution. As the pH of the HF solution was increased, at the same initial HF concentration, the SiO2/Si3N4 etching selectivity was increased. Meanwhile, the etching selectivity of SiO2 over Si3N4 was increased with the initial concentrations of HF increased, at a fixed pH of the solution. To investigate the reason for the dependencies of the SiO2 and Si3N4 etching rates on pH and initial concentrations of HF, the concentrations of each fluorine species were calculated. As a result, the etching mechanisms and the etching behaviors of SiO2 and Si3N4 in the HF solutions were suggested. Based on the etching kinetics of SiO2 and Si3N4, a patterned SiO2/Si3N4 multi-stack structure etching conditions were controlled to investigate the SiO2/Si3N4 selective etching ability of the HF solution. The cross-sectional FE-SEM images visually showed that high SiO2 etching selectivity compared to Si3N4 was achieved. As a result, highly selective SiO2 etching without loss of Si3N4 was obtained by adjusting only the concentrations of HF and NH4F, without any special additives through the suggested SiO2 and Si3N4 etching kinetics.

(Invited) Low Energy Methods for Highly Selective Etching and Surface Treatment of Advanced Nanodevices

In the pursuit of higher performance semiconductors, device length scales continue to shrink down to nanometer dimensions with emerging chip designs increasingly dependent on 3D structures to maintain scaling. Memory manufacturers have already deployed 3D NAND devices with ongoing development for 3D DRAM devices. Advanced logic manufacturers have already deployed 3D FinFET devices and are beginning to deploy more complex GAA (Gate-All-Around) 3D devices as well. Building 3D structures has increased the need for more sophisticated selective etching. As these selective etches have become critical to the formation of the device, atomic precision material loss is required with low contrast materials. We review several materials systems where insufficient selectivity control in plasma-based radical etch necessitates innovative approaches such as atomic layer passivation, low energy metastable activated radicals and plasma-less low energy thermal chemical etching.Dummy polysilicon removal requires full removal of the polysilicon with minimal film loss to dielectric films such as silicon oxide and silicon nitride. While polysilicon can be removed by either wet etch or dry etch, each approach has certain limitations that narrow the overall process window. Wet etch chemistries such as TMAH (tetramethyl ammonium hydroxide) anisotropically etch polysilicon preferentially along crystalline planes which can result in silicon residues at the bottom corners of trenches. Highly isotropic dry etch radical chemistries minimize silicon residues but have greater tendency to damage the underlying epitaxial silicon layer due to either excessive film loss or halogen radical penetration through the encapsulating film. We show that the introduction of atomic layer passivation modifies the top monolayer of an oxide encapsulation layer and consequently widens the epi damage-free window.Selective mask removal requires full removal of the organic mask with high selectivity to exposed epitaxial silicon surfaces. While plasma-generated radicals have been effectively used for some time, it has become increasingly difficult for both advanced FinFET and GAA devices as the epi film loss requirements lower to a single atomic layer. We propose the tail energy distribution of reactive species formed in the plasma region is the driving factor for epitaxial film loss. To reduce these effects, we apply MARS (Metastable Activated Radical Source) technology where reactive species are indirectly formed outside the plasma region though collisions with metastable intermediates. The result is a significant reduction in higher energy species flux to the surface corresponding to a lower epi loss than conventional radical approaches.GAA device integration relies on depositing and subsequently removing SiGe layers to form Si-nanowires or nanosheets. Fluorine radical-based chemistries have limited selectivity to silicon because the bond strength difference between Si-Si and Si-Ge is exceedingly narrow and about 0.3 eV. We show a thermal chemical etching approach that achieves substantially higher SiGe:Si selectivity than radical etching on both blanket films and test structures. In addition, we highlight the strict film loss requirements that require highly selective native oxide removal prior to removing SiGe layers. We describe a thermal chemical etching approach that applies wet etch mechanisms in a vacuum environment to achieve high selectivity to both silicon and silicon nitride.

Observation of orbital angular momentum from an ultrathin topological insulator metasurface.

Orbital angular momentum (OAM) existing in the vortex light beam with isolated singularities and spiral phase distribution presents significant applications in optical communications and light-field manipulation. The generation of OAM based on plasmonic metasurfaces is generally limited by the large optical loss and weak tunability of metal materials. Three-dimensional (3D) topological insulators (TIs) with insulating bulk states and topologically protected surface states allow the excitation of surface plasmons with low loss in the high-frequency region. Herein, we designed and fabricated an ultrathin Sb2Te3 TI plasmonic metasurface using the magnetron sputtering deposition and focused ion beam lithography. The results show that the 18 nm thick TI metasurface can efficiently generate surface plasmon resonances (SPRs) in the visible spectrum, which can effectively modulate the spatial phase of incident light for the generation of OAM. We find that the OAM conversion efficiency of the TI-based metasurface is remarkable compared with that of the gold-based metasurface. The experimental results obtained by a self-built OAM testing system demonstrate that the ultrathin TI metasurface can generate a distinct vortex beam with a first-order topological charge. This work will provide a new approach for generating OAM in ultrathin structures and exploring the applications of TIs in light-field manipulation.

Carbon Footprint of Additively Manufactured Precious Metals Products

Traditionally, precious metals are processed by either lost-wax casting or the casting of semi-finished products followed by cold or hot working, machining, and surface finishing. Long process chains usually conclude in a high material input factor and a significant amount of new scrap to be refined. The maturing of Additive Manufacturing (AM) technologies is advantageous with regard to resources among other criteria by opening up new processing techniques like laser-based powder bed fusion (LPBF) for the production of near net shape metal products. This paper gives an insight into major advantages of the powder-based manufacturing of precious metal components over conventional methods focusing on product carbon footprints (PCF). Material Flow Cost Accounting (MFCA) for selected applications show energy and mass flows and inefficient recoverable losses in detail. An extended MFCA approach also shows the greenhouse gas (GHG) savings from avoiding recoverable material losses and provides PCF for the products. The PCF of the precious metals used is based on a detailed Life Cycle Assessment (LCA) of the refining process of end-of-use precious metals. In the best case, the refining of platinum from end-of-life recycling, for example, causes 60 kg CO2e per kg of platinum. This study reveals recommended actions for improvements in efficiency and gives guidance for a more sustainable production of luxury or technical goods made from precious metals. This exemplary study on the basis of an industrial application shows that the use of AM leads to a carbon footprint of 2.23 kg CO2e per piece in comparison with 3.17 kg CO2e by conventional manufacturing, which means about a 30 percent reduction in GHG emissions and also in energy, respectively.

Effect of dispersion technique and applied load on the dry sliding wear behavior of combined stir-squeeze-cast AA6061–0.5 wt % CNT composite against a steel counter body at both room temperature and elevated temperature

Wear behavior of three different AA6061-0.5 wt% CNT composites fabricated using different dispersion techniques by stir-squeeze-casting have been studied against a steel ball counter body. The uniform CNT distribution in composites fabricated by dropping pellets of Al-powder and CNT (PD composite) yields the lowest coefficient of friction (COF) and specific wear rate (SWR) for both the composite material and the counter body. Both COF and SWR increase as the load increases from 5 N to 10 N, but drop as the load increases further to 15 N. Even at 150 °C, the presence of CNTs improved the tribological performance of AA6061. A detailed study of CNT morphologies on the worn surface and Raman spectroscopy indicate their beneficial role as a solid lubricant to reduce COF and material loss during wear.

Losses and emissions in polypropylene recycling from household packaging waste

In this study we replicated a typical high-quality post-consumer polypropylene (PP) recycling process to investigate its losses and emissions and study potential improvements. To our knowledge this is the first time that quantitative measurements on all process steps have been performed instead of an accumulated yield and emissions in water. In the process an overall PP yield of 85 wt% based on pure PP input is achieved. The loss of target material is largest at the two mechanical dryer steps (6.6 wt%) and in the wet grinder combined with friction washers (4.0 wt%). In the process we observed approx. 3.9 wt% of the PP input as microplastics in the wastewater before the dissolved air flotation unit which is capable of 97–99 % mass-based removal of microplastics (MPs). Around 330 µg of PP was emitted to air at the mechanical drying step for each kg of input material. This is a very low mass fraction, but considering the particle size distribution the number of particles is vast. This emission can be reduced by using air filters at locations where MPs are generated. To reduce losses and emissions we investigated a few potential process changes. Compared to current practice, positive results were achieved by ensuring that the knives of the wet grinder remain sharp. The mechanical drying process can be improved by lowering the centrifugal speed which reduces the generated microplastics here from 4 wt% to 1 wt% without significantly affecting the moisture content.

Multiple Fano resonances in all-dielectric porous array structures

High Q metasurfaces play an important role in fields such as high-sensitivity sensing and nonlinear optics due to their strong localized electromagnetic field enhancement. Although ultra-high Q resonance has been developed in the field of optics, it is still a challenging task due to the loss of dielectric materials, design and fabrication of nanostructures. In this paper, we have designed an all-dielectric symmetric perforated array structure that supports multiple Fano resonances within the 0–1 THz range and realizes the anapole mode through this array perforation structure. By calculating the phase difference between different modes at the resonance frequencies, we explain the mechanism of the formation of resonance-coupled BIC. The Q-factors of the three modes have been calculated, where the highest Q-value can be up to 2703, it is excited by the MQ. Then, we analyzed the sensing performance and the highest sensitivity can reach 27,000 nm/RIU. Since the metasurface always maintains c_4v symmetry and mirror symmetry, all three resonances are polarization independent. The proposed metasurfaces can be applied to light-matter interactions, enhanced nonlinear response, and sensing.

Analisis Yuridis Terhadap Pelaku Tindak Pidana Penganiayaan Anak (Studi Putusan: Nomor 2561/PID.SUS/2022/PN MDN)

Child abuse not only causes material losses but also profound psychological impacts, such as emotional and psychological trauma. One case of child abuse is recorded in Decision Number 2561/Pid.Sus/2022/PN Mdn. In this case, the defendant M. Syafri, also known as Muhammad Saprik, committed violence against a child, Abdan Yolanda Lubis, causing a torn wound on the child’s left ring finger. As a result, the defendant was sentenced to 2 years in prison. Based on Law Number 23 of 2022 on Child Protection, Article 80, paragraph (1) stipulates that perpetrators of child abuse, such as assault, can be sentenced to a maximum of 3 years and 6 months in prison, without the possibility of detention. The method used in this study is normative legal research, descriptive-analytical in nature, employing both a statutory approach and a case study approach. This research uses secondary data consisting of primary, secondary, and tertiary legal materials. The analysis results indicate that the legal provisions regarding the detention of perpetrators of child abuse are regulated in Article 76C of Law Number 35 of 2014. The law prohibits anyone from committing violence against children, either directly or through an order. Legal protection for children who are victims of abuse is carried out preventively through law enforcement and repressively through socialization to children and related institutions. The analysis of the verdict indicates that the punishment imposed on the defendant is considered too lenient and does not match the suffering experienced by the victim. The prosecutor's demands and the ruling are not maximal, while the law stipulates a prison sentence of 3 years and 6 months and/or a fine of up to IDR 72,000,000.

Advancing aluminum-ion batteries: unraveling the charge storage mechanisms of cobalt sulfide cathodes

Rechargeable aluminum-ion batteries (AIBs) stand out as a potential cornerstone for future battery technology, thanks to the widespread availability, affordability, and high charge capacity of aluminum. However, the efficacy of current AIBs on the market is significantly limited by the charge storage process within their graphite cathodes. To fully realize the capabilities of AIBs, the discovery of a new cathode material is essential. Transition metal sulfides present an attractive option for cathode materials, although there has been a variety of conflicting reports regarding the exact nature of their charge storage mechanisms. This paper investigates cobalt sulfide (CoSx) cathodes in AIBs, with a particular focus on deciphering the mechanisms of charge storage. Through synthesis, electrochemical testing, and post-cycling characterization, we illuminate the roles of AlCl4− intercalation, cobalt sulfide to Al2S3 conversion, and sulfur to Al2S3 conversion in charge storage. As cycling progresses, Al2S3 synthesis from segregated sulfur segments emerged as the predominant mechanism, showcasing its potential to fully leverage the high capacity of aluminum metal and propel AIBs towards higher energy densities. Despite these promising findings, the study also uncovered significant challenges, notably material loss, intra-cathode diffusion limitations, and irreversible reactions that precipitously diminish charge capacity over time. These issues highlight the critical need for enhanced electrode stability, improved electrolyte compatibility, and accelerated aluminum diffusion. The research paves the way for further exploration of transition metal sulfides as cathode materials in AIBs, highlighting the imperative for innovations that bolster mechanical and chemical stability while optimizing ion transport. This work not only contributes to the fundamental understanding of charge storage in AIBs but also charts a course for the development of more durable and efficient battery systems.

Achieving High Performance with Less Energy Consumption: Intermittent Ultrasonic-Mediated Operation Mode for Fe/V Non-Aqueous Redox Flow Battery

Deep eutectic solvents (DESs) have attracted much attention as sustainable electrolytes for redox flow batteries. Despite the tremendous advantages of DES-based electrolytes, their high viscosity property has a negative effect on their mass transfer, limiting current density and power density. The ultrasonic effect has been demonstrated as an efficient strategy to improve mass transfer characteristics. Incorporating ultrasonic waves into a deep eutectic solvent (DES) electrolyte enhances the mobility of redox-active ions, thereby accelerating the reaction dynamics of the Fe(III)/Fe(II) redox pair. This enhancement makes it suitable for use in non-aqueous electrolyte-based redox flow batteries. However, it is necessary to consider the loss of ultrasonic on the internal structure of the battery, as well as the loss of battery component materials and ultrasonic energy consumption in practical applications. Moreover, the continuous extension of the duration of ultrasonic action not only hardly leads to a more significant improvement of the battery performance, but is also detrimental to the energy and economic savings. Herein, intermittent ultrasound is used to overcome the quality transfer problem and reduce the operating cost. Good electrochemical performance enhancement is maintained with a roughly 50% reduction in energy consumption values. The mechanism as well as the visualization of the pulsed ultrasonic field on each half cell has been envisaged through fundamental characterization. Finally, the feasibility of interrupted ultrasonic activation applied to Fe/V RFB using DES electrolytes has been demonstrated, demonstrating similar behavior with continuous ultrasonic operation. Therefore, the interrupted ultrasonic field has been found to be a more effective operation mode in terms of energy cost, avoiding alternative undesirable effects like overheating or corrosion of materials.

Unusual Lignocellulosic Bioresins: Adhesives and Coatings for Metals and Glass.

This minireview presents some unusual but encouraging examples of lignocellulosic-based adhesives and coatings used for metals, glass, and some other difficult-to-adhere materials. The reactions and applications presented are as follows. (i) The reactions of tannins and wood lignin with phosphate salts, in particular triethylphosphate, to adhere and join steel and aluminum to Teflon, in particular for non-stick frying pans. These adhesive coatings have been shown to sustain the relevant factory industrial test of 410 °C for 11 min and, moreover, to present a 50% material loss even at 900 °C for 5 min. (ii) Non-isocyanate polyurethanes (NIPU) based on glucose and sucrose as coatings of steel and glass. These were obtained by the carbonation of carbohydrates through reaction with the inexpensive dimethyl carbonate followed by reaction with a diamine; all materials used were bio-sourced. Lastly, (iii) the use of citric acid-based adhesive coupled with any hydroxyl groups carrying material for coating metals is also described. These three approaches give a clear indication of the possibilities and capabilities of biomaterials in this field. All these are presented and discussed.

A method for estimating lithium-ion battery state of health based on physics-informed machine learning

Data-driven approaches are widely applied in estimating the State of Health (SOH) of Lithium-Ion Batteries (LIB). However, these methods often suffer from a lack of interpretability. To address this issue, this article proposes a method called Battery Physics-Informed Neural Network (BPINN) to enhance the interpretability of the Feedforward Neural Network (FNN) in SOH prediction. This article is based on the concept of Physics-Informed Neural Networks (PINN). Features are initially extracted from Incremental Capacity (IC) curves to characterize the battery aging process. Notably, IC curve peaks (P-IC) reflect electrochemical reactions during charge and discharge cycles. The degradation of these peaks is directly related to the loss of active materials, causing SOH reduction. This article transforms the monotonic relationship between P-IC and SOH into a physical constraint, which is embedded into model training. Furthermore, during prediction, a secondary “training” based on physical constraints is applied to the FNN prediction results, enhancing the model's interpretability and accuracy. The proposed method is validated using publicly available battery datasets from NASA and the University of Oxford. Results show BPINN effectively improves SOH prediction accuracy, reducing the Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) to below 0.4 %.

Research on aging mechanism and capacity attenuation of automotive lithium-ion batteries

In order to investigate the internal mechanism and the variation law of capacity attenuation of LIBs, a simplified electrochemical model of the LIBs was established using the nickel-cobalt-aluminum LIBs as the research object, and the aging model of solid electrolyte interface SEI growth and lithium evolution was added to simulate the electrochemical behavior of the batteries. The results showed that the porosity of the anode/diaphragm reduced continually at the start of the cycle, while the SEI film grew continuously. The loss of active materials accelerated as the number of cycles increased, while the side reaction of lithium development continued. Finally, the aging mechanism was confirmed by using microscopic morphology. The results show that the negative particles are obviously crushed and contain white deposited substances. The formation of these compounds increases the oxygen content, reduces the carbon content, reduces the porosity of the electrode, increases the overpotential of the electrolyte transport, and becomes the main reason for the attenuation of the battery life. Finally, the positive particles expand and break, which leads to the sudden reduction of the battery capacity. This study determined the evolution process of aging mechanism in the whole life cycle, and provided a theoretical basis for the establishment of mechanism aging model.

Penetration of a spherical vortex into turbulence

The penetration of a spherical vortex into turbulence is studied theoretically and experimentally. The characteristics of the vortex are first analysed from an integral perspective that reconciles the far-field dipolar flow with the near-field source flow. The influence of entrainment on the vortex drag force is elucidated, extending the Maxworthy (J. Fluid Mech., vol. 81, 1977, pp. 465–495) model to account for turbulent entrainment into the vortex movement and vortex penetration into an evolving turbulent field. The physics are explored numerically using a spherical vortex (initial radius $R_0$ , speed $U_{v0}$ ), characterised by a Reynolds number $Re_0(=2R_0U_{v0}/\nu$ , where $\nu$ is the kinematic viscosity) of 2000, moving into decaying homogeneous turbulence (root-mean-square $u_0$ , integral scale $L$ ) with turbulent intensity $I_t=u_0/U_{v0}$ . When the turbulence is absent ( $I_t=0$ ), a wake volume flux leads to a reduction of vortex impulse that causes the vortex to slow down. In the presence of turbulence ( $I_t> 0$ ), the loss of vortical material is enhanced and the vortex speed decreases until it is comparable to the local turbulent intensity and quickly fragments, penetrating a distance that scales as $I_t^{-1}$ . In the experimental study, a vortex ( $Re_0\sim 1490\unicode{x2013}5660$ ) propagating into a statistically steady, spatially varying turbulent field ( $I_{ve}=0.02$ to 0.98). The penetration distance is observed to scale with the inverse of the turbulent intensity. Incorporating the spatially and temporally varying turbulent fields into the integral model gives a good agreement with the predicted trend of the vortex penetration distance with turbulent intensity and insight into its dependence on the structure of the turbulence.

Investigation on novel ultralight weight thermally insulated fireproof composite

Abstract This study highlights the performance of ultra-lightweight fireproof composite. Polyacrylonitrile based carbon fiber (CF) has been reinforced in Polyetherimide (PEI) polymer to develop the composite. The Surfac2e of CF and PEI film was modified by low-pressure plasma to improve the bonding strength between matrix and reinforcement. The polymeric composite was fabricated by compression molding with a pressure of 2 bar, temperature of 380 °C and holding time of 30 min. CF/PEI composite was used to make a hybrid composite by layering of silicone foam in between the layers. The hybrid composite was exposed to a Bunsen burner under sustained flame for a duration of 10 min. The composite panel’s flame-facing side reached 676.2 °C after 10 min of fire exposure, while the temperature on the other side only reached 58.2 °C. The fabricated hybrid composite was exposed to very low temperature in order to test its ability of thermal insulation under extreme cold temperature. Over the specific period of testing, the temperature of the dry ice decreased from 25 °C to −3.1 °C. After exposure to fire, only minimal loss of material was observed. The hybrid composite of carbon fiber and PEK film, sandwiched between silicone foam, exhibits excellent fire resistance due to its high limiting oxygen index. This composite is considered to be among the best thermally insulating and fire-resistant materials. Thermogravimetric analysis of carbon fiber and PEI-Carbon fiber composite was performed to determine the optimal processing temperature of compression molding for the composite, upon heating, it showed a modest weight decrease of 6.053%. The composite shows a significant improvement of impact resistance, compressive strength and thermal stability. A simulation model was developed under Ansys fluent software for both heating and cooling. The analysis of developed model also shows similar results.

Evaluation of Wear Resistance in Tungsten-Doped Diamond-like Carbon Coatings (WC/C) on Coated and Uncoated Surfaces Under Starved Oil Lubrication with R452A Refrigerant.

This article assesses the potential of using a diamond-like carbon coating doped with tungsten, a-C:H:W (WC/C), on the sliding pairs of refrigeration compressors. The ability of WC/C coating to provide low wear and a low coefficient of friction was experimentally verified in a specific refrigeration compressor operating environment (lubrication with oil diluted with refrigerant) and under extreme operating conditions (starved lubrication with a small amount of oil). Conditions of starved lubrication with a substance of reduced lubricity promote a temperature increase and high mechanical (friction) stresses on the surface of the sliding pairs. These situations can hinder the effective operation of WC/C coatings. Comparative wear tests were carried out for S235JR steel samples with and without WC/C coating. It was found that the samples with the WC/C coating had the lowest wear values and the lowest friction coefficients (approximately 0.06). A low coefficient of friction suggests that even a small amount of oil (one drop) is likely sufficient to achieve mixed lubrication conditions between the tested sliding surfaces and reduce material loss. The tested WC/C coating can protect sliding friction pairs in refrigeration compressors under extreme operating conditions caused by a lack of oil. Less friction reduces the need for energy to drive the refrigeration compressor. Additionally, the significance of this research is highlighted by the fact that the wear tests were conducted using R452A, a novel, eco-friendly refrigerant.

Acoustic sub-wavelength imaging via a virtual super-lens

Overcoming the diffraction limit has been a long-lasting pursuit for researchers owing to the great potential it offers in going beyond the fundamental resolution restriction in imaging processes. In acoustics, meta-lenses have been a promising way to achieve sub-wavelength imaging, the practical application of which, however, has been limited by expensive material manufacturing, complex system setup, and material loss. Here, we propose a set of procedures equivalent to a virtual super-lens that selectively amplifies the evanescent wave components in the measured acoustic field spectrum, thereby enabling super-resolution imaging without any auxiliary setups or purposely designed super-lens. The proposed virtual super-lens is experimentally verified by considering the imaging of an irregularly shaped sample with sub-wavelength features. We further demonstrate the robustness of the high-quality imaging performance remains acceptable with some environment background noises. In the light of the simple experimental setup involved, our proposed method is flexible and can be readily applied to various practical imaging scenarios.