bluuebunny/crossref_metadata_2025 huggingface dataset:
Synergistic Effects of Plastic Deformation and Chloride Ions on Localized Corrosion of Steel Rebars in Concrete
Authors: Doi Kotaro , Hiromoto Sachiko
Published: December 2024

In typical concrete environments, alkalinity is generally maintained, contributing to the superior corrosion resistance of reinforcing steels due to the presence of a passive film. However, the passive film can be broken by some corrosion factors, and the corrosion initiates on the reinforcing steel. In this study, we studied the dissolution and repassivation behavior of reinforcing steel during rapid elongation in a simulated concrete solution containing Cl- to elucidate the effects of deformation and Cl- on the localized corrosion behavior of the reinforcing steel in concrete.

Commercial reinforcing steel samples were prepared and shaped for tensile testing. These samples were then placed in an electrochemical cell filled with a simulated concrete solution (saturated Ca(OH)2 solution) and attached to a tensile testing machine. Hausmann previously reported that corrosion of reinforcing steel occurs when the ratio of chloride ions to hydroxide ions ([Cl-] / [OH-]) exceeds 0.6 in a stress-free concrete environment1). To examine the effect of lower concentrations of Cl- on dissolution and repassivation when the passive film is broken by mechanical loading, NaCl was added to the simulated concrete solution at concentrations yielding [Cl-] / [OH-] ratios of 0, 0.2, and 0.4. Initially, the samples were polarized at the corrosion potential, followed by rapid elongation at a straining rate of 0.67 s-1 (corresponding to a tensile speed of 10 mm/s). The transient behaviors of strain, stress, and current were recorded with time.

An increase in current was observed during plastic deformation, whereas little increase was noted during elastic deformation. This suggests that the passive film on reinforcing steel remains intact or experiences minimal breakdown during elastic deformation, whereas dissolution occurs during plastic deformation due to the substantial increase in newly exposed surface area resulting from the formation of slip steps.

Following the finishing of elongation, the current rapidly decreased to pre-straining levels as a result of repassivation in the solution with [Cl-] / [OH-] ratio of 0. However, in solutions with [Cl-] / [OH-] ratios of 0.2 and 0.4, the current did not decrease rapidly and exhibited stagnation. In these cases, the charge generated after deformation significantly increased, leading to substantial metal dissolution. Examination of the sample surface via field emission scanning electron microscopy (FE-SEM) revealed localized corrosion along slip steps, leading to the extensive metal dissolution. These findings suggest that the critical chloride ion concentration for reinforcing steel corrosion in concrete environments is lower than that reported for stress-free environments.

1) A. Hausmann, Materials Protection, Vol. 6, No. 11, pp. 19-23 (1967).
Effect of Microalloying on Localized Corrosion and Mechanically Induced Corrosion of Magnesium-Zinc Based Ternary Alloys
Authors: Jiang Pingli , Blawert Carsten , Zheludkevich Mikhail
Published: December 2024

The Magnesium-zinc system (Mg-Zn) holds significant promise for developing cost-effective Mg alloys with enhanced strength and favorable corrosion performance. In this study, we explored low-Zn Mg-Zn alloys micro-alloyed with various ternary elements to achieve an optimal balance between corrosion resistance and mechanical properties. By investigating the impact of these alloying elements on the microstructures and localized corrosion behavior of Mg0.5Zn0.2X and Mg4Zn0.2X alloys (in wt.%), we identified three promising alloys: Mg0.5Zn0.2Ca, Mg0.5Zn0.2Ge, and Mg4Zn0.2Sn. Subsequently, we applied hot extrusion at varying speeds to enhance corrosion resistance and strength. Interestingly, the corrosion rates of Mg0.5Zn0.2Ge and Mg4Zn0.2Sn alloys decreased after extrusion, while that of Mg0.5Zn0.2Ca alloy remained relatively unaffected. Notably, the corrosion mechanism of Mg0.5Zn0.2Ge alloy shifted from localized corrosion to uniform corrosion due to refined microstructure and increased Zn participation in the corrosion product layer.

The tensile properties of all alloys deteriorated over time due to corrosion in salt spray, particularly when localized corrosion occurred. However, the trend in tensile properties closely correlated with the alloys’ corrosion resistance in salt fog. The corrosion fatigue behavior of the alloys was strongly linked to their corrosion behavior in various solutions, especially for the Mg4Zn0.2Sn alloy. We also investigated the susceptibility of these alloys to stress corrosion cracking (SCC) in four different electrolytes using constant load tests. Both Mg0.5Zn0.2Ca and Mg4Zn0.2Sn alloys exhibited resistance to SCC across all environments. In contrast, the Mg0.5Zn0.2Ge alloy showed susceptibility to SCC in all environments, particularly in deionized water. This susceptibility was attributed to the different corrosion product/substrate interfaces formed in various solutions, which influenced crack development.
(Invited) Nanostructured Silicon Loaded with FePt Nanoparticles – a Composite with High Energy Product
Authors: Rumpf Klemens , Granitzer Petra , Gonzalez-Rodriguez Roberto , Coffer Jeffery
Published: December 2024

In this work silicon nanotubes (SiNTs) and porous silicon (PSi) are loaded with Co nanoparticles (NPs) and hard magnetic FePt nanoparticles. These composite systems are used as platform to create nanomagnet-arrays. The magnetic response of FePt-loaded composite materials is investigated, which have potential in high-performance magnets and as rare earth magnet alternatives. These results are compared with the PSi/SiNTs-Co composites. PSi/FePt demonstrates superior hard magnetic behavior with a higher coercivity and remanence compared to SiNTs/FePt. Varying the Fe molar ratio in deposits results in a small variation of the coercivity of about 5%. FePt-loaded samples consistently show increased coercivity and remanence compared to Co-loaded samples, with PSi exhibiting a stronger effect compared to SiNTs. The dependence of the magnetization on the temperature between 4.2 K and 300 K shows a decrease of the coercivity with increasing temperature, which is common for a ferromagnetic behavior. High temperature magnetization measurements allow to determine the Curie Temperature (TC) of PSi and SiNTs loaded with FePt NPs. The PSi templated system offers a lower TC compared to the SiNTs composite system.
Effect of Thermal Runaway Trigger Methods for Battery Safety Characterization
Authors: Boovaragavan Vijayasekaran , Mallarapu Anudeep , Sunderlin Nathaniel , Tamashiro Matthew , Peabody Christina , Pelloux-gervais Thibault , Li Xin , Sizikov Gregory
Published: December 2024

Lithium-ion batteries are prone to risks with fire hazard due to the possibility of thermal runaway propagation. During battery product development and subsequent safety tests for design validation and safety certification, the thermal runaway onset is triggered by various test methods such as nail penetration, thermal ramp, or external short circuit. This failure initiation method affects the amount of heat contributions and the composition of gas generations. This study1 compares two such trigger methods, by external heating and by using a thermally activated internal short circuit device (ISCD). The effects of the trigger method on total heat generation are experimentally investigated within 18650 cylindrical cells at single cell level as well as at multiple cell configuration level.

During thermal abuse conditions, it is known that internal short circuits occur before thermal runaway, but this joule heating does not contribute much to heat generation2. But during internal short circuits initiating at lower temperatures, joule heating plays a major role in thermal runaway process. Previous modeling studies have enhanced our understanding of the role of multiple physical processes during thermal runaway3-4. In this study we use a combination of models and experiments to characterize battery safety in terms of abuse tolerance, severity of thermal runaway and propagation. The severity of failure was observed to be worse for cells with ISC devices at single cell level whereas quite opposite results were observed at multiple cell configuration level. A preliminary numerical analysis was performed to better understand the battery safety performance with respect to thermal runaway trigger methods and heat transfer conditions.

Mallarapu, A., Sunderlin, N., Boovaragavan, V., Tamashiro, M., Peabody, C., Pelloux-gervais, T., Li, X., Sizikov, 2024, Effects of Trigger Method on Fire Propagation during the Thermal Runaway Process in Li-ion Batteries, Journal of The Electrochemical Society, 171 040514

Ren, D., Feng, X., Liu, L., Hsu, H., Lu, L., Wang, L., He, X., Ouyang, M., 2021, Investigating the relationship between internal short circuit and thermal runaway of lithium-ion batteries under thermal abuse condition, Energy Storage Materials 34, 563–573

Feng, X., He, X., Ouyang, M., Wang, L., Lu, L., Ren, D., Santhanagopalan, S., 2018, An electrochemical-thermal coupled overcharge-to-thermal-runaway model for lithium ion battery, Journal of The Electrochemical Society, 165 A3748

Coman, P. T., Darcy, E. C., Veje, C. T., White, R. E., 2017. “Modelling Li-Ion cell thermal runaway triggered by an internal short circuit device using an efficiency factor and arrhenius formulations.” Journal of The Electrochemical Society, 164 A587
Second Life of Lithium-Ion Batteries: Effects of Temperature Cycling
Authors: Ezeigwe Ejikeme Raphael , Woll Sivert Andre , Erichsen Lene Therese Backus , Wind Julia , Burheim Odne Stokke
Published: December 2024

Extending the lifespan of lithium-ion batteries (LIBs) can be achieved either by repurposing batteries under similar conditions within the same application segment, as a first-life extension, or by extending them into different segments with different operations as a second-life application. In the latter case, it is crucial to comprehend not only the remaining capacity and performance properties but also the safety aspect. To address these considerations, we cycled 30Ah NMC 433 graphite LIBs under different conditions to State of health capacities of 70-80 % and subsequently, subjected them to softer degradation environments. We then deployed Incremental capacity analysis (dQ/dV) (ICA) to understand degradation mechanisms, with a particular focus on how to detect Li plating. Cycling conditions and repeated measurements revealed rapid degradation, particularly during low-temperature cycling. Combining ICA with ex-situ post-mortem analysis methods allowed for Li indications and facilitated the comparison of capacity losses with degraded performances versus degraded safety issues [1], [2].

Overall, batteries cycled at high temperatures exhibited poor performance in terms of remaining capacity as depicted in Figure 1, and high resistance without significantly lowering thermal runaway temperatures. This contrasts with low-temperature degradation, where the thermal onset temperature decreases to as low as 85 oC. Intermediate temperature degradation resulted in some loss in performance, namely resistance and capacity, but not in safety. Using ICA alongside detailed more aggressive degradation allowed for detecting safety warning mechanics during the degradation testing.

References

[1] L. Spitthoff, P. J. S. Vie, M. S. Wahl, J. Wind, and O. S. Burheim, “Incremental capacity analysis (dQ/dV) as a tool for analysing the effect of ambient temperature and mechanical clamping on degradation,” J. Electroanal. Chem., vol. 944, p. 117627, 2023, doi: https://doi.org/10.1016/j.jelechem.2023.117627.

[2] L. Spitthoff, P. R. Shearing, and O. S. Burheim, “Temperature, Ageing and Thermal Management of Lithium-Ion Batteries,” Energies, vol. 14, no. 5. 2021. doi: 10.3390/en14051248.

Figure 1
Selection of Design Parameters to Reduce Maintenance
Authors: Shifler David
Published: December 2024

Seawater is a complex mixture of chemical, physical and biological species whose characteristics can be influenced by many factors such as geography, temperature, depth, ocean currents, etc. For centuries it has been recognized that seawater is the most corrosive natural environment towards engineering materials, particularly many metals and alloys. Some constituents and circumstances can accelerate attack while others may retard it. Corrosivity can vary to some degree, for example, with geographic location; however, no seawater, in its natural state, is considered to be non-corrosive anywhere in the world. A good understanding of the influence of environmental factors on seawater corrosivity, coupled with experience and test data can help optimize selection and/or utilization of materials in practical marine applications.

Marine environments are typically classified in terms of “zones” to which materials are exposed in given situations, for example, atmospheric, splash-and-spray, tidal, immersion or submerged, and bottom-mud or sediment. There are many complex environmental factors that influence seawater corrosivity. Many of these factors are interrelated and often synergistic. This can lead to unexpected behavior of materials performance in specific situations.

Materials and equipment that function in the marine environment are subjected to aggressive conditions. Salt is pervasive in all marine environments. Corrosion is a leading driver for maintenance and overall lifecycle costs. Proper material choices, corrosion control measures, and employing effective design to avoid corrosion are the most effective means to reduce maintenance and life cycle costs.

Design decisions are seldom absolute. There are multiple factors that should be considered when designing a system, some of which may override corrosion concerns. A designed component or system must satisfy its functional purpose, but corrosion may occur at critical sites that interfere with its true functionality.

The United States Navy is currently experiencing a growing backlog of maintenance for Navy ships caused by several factors, one of which is poor planning for sustainment during acquisition. It appears that past design practices are not meeting the maintenance backlog. A new approach to design is embracing digital engineering for new ship designs and providing multiple maintenance options virtually to determine the most effective pathway that lead to reduced maintenance. ONR and the Navy is attempting to develop models that will integrate corrosion databases with design software that could lead to design choices on corrosion resistance with other functional properties.
Investigation on Corrosion Behavior of Nickel Plated Steel in Copper Sulfate Solution and It's Applicability As a Defect Inspection
Authors: Lee Seung Hwan
Published: December 2024

The effects of defect on the corrosion behavior of electrolytically Ni-plated steel in copper sulfate solution were investigated using electrochemical methods and surface characterization techniques. The results show that copper is deposited on the Ni surface not on steel exposed through defect. In the case of incompletely-open defects, weight gain on the Ni surface due to the copper deposition is decreased with immersion time and levelled off within 3 hours. However, the copper deposition on the Ni surface with fully-open defects exhibits continuous weight gain by vertical growth of copper layer. This is because copper deposition proceeds in the lateral direction preferentially until exposure of steel to the corrosive environment is blocked in incompletely-open defects where connection between copper deposition layers on separate Ni plating is accomplished. In contrast, in fully-open defects, vertical growth of copper deposition layers on separate Ni plating is observed. The vertical growth of the copper deposition layer in fully-open defects means that the interface between the substrate and nickel plating layers is continuously exposed to a corrosive environment, which eventually leads to delamination of the Ni plating layer from its substrate.

The difference between incomplete and complete opening of defects is related to the defect area of the Ni plating layer, but verification of further electrochemical factors is required to distinguish the structural difference. These defects vary depending on the substrate and Ni plating process, but are inevitably accompanied by the subsequent forming process of Ni-plated steel. Since these defects are a major factor in determining the durability of the final products related to corrosion, it is important for manufacturers to identify and screen for these defects before moving on to the next step. Therefore, this study aims to identify the differences in copper sulfate test results according to the defect types and the correlation with product's durability due to corrosion. To verify this, analysis of the interfacial reaction through EIS (electrochemical impedance analysis) and current density and its overvoltage according to cathodic polarization related to the reaction of the copper deposition are in progress.
Galvanic and Local Corrosion of Aluminum Alloy 6061-T6 Coupled to Non-Passivating and Passivating Alloys
Authors: Wohner Natalie , Hihara Lloyd H.
Published: December 2024

Marine and aerospace structures sometimes combine lightweight aluminum alloys with dissimilar metals to optimize mechanical performance and reduce costs. Unfortunately, the exposure of such dissimilar couples in a harsh environment can cause severe corrosion damage to the aluminum structure due to its position in the galvanic series. Corrosion of Aluminum Alloy (AA) 6061-T6 coupled to non-passivating and passivating alloys was studied to elucidate galvanic effects on local corrosion. In this work, local and galvanic corrosion were quantified, the effects of cathode material on local electrolyte pH were explored, and a relationship between pH and local-corrosion of AA6061-T6 was established.

Experimental studies quantified local and galvanic corrosion of AA6061-T6 coupled to 316 stainless steel, copper, titanium alloy Ti6Al4V, and 316 stainless steel coated with titanium nitride, chromium nitride, and a sol-gel nano-coating. Galvanic couples were misted with 3.15 wt.% sodium chloride solution and exposed in a controlled temperature-humidity chamber. Galvanic currents were measured during exposure, and the total mass loss of the aluminum alloy was determined to quantify the corrosion damage. Exposure tests showed that galvanic corrosion decreases over time and accounts for less than 15% of the total corrosion of AA6061-T6. Therefore, most aluminum corrosion damage was caused by local corrosion. In addition, immersion experiments of AA6061-T6 galvanic couples in gelled 3.15 wt.% NaCl solutions showed that galvanic coupling influences the evolution of electrolyte pH leading to severe acidification at the aluminum anode surface and alkalization around the cathode. The solution pH at the aluminum surface was decreased by galvanic action and severity of pH decrease depends on galvanic couple materials and design. To quantify the effect of acidity on local corrosion of AA6061-T6, potentiodynamic polarization tests were performed in aerated and deaerated 3.15 wt.% NaCl solution adjusted to different pH values. Anodic dissolution reactions and cathodic oxygen reduction reactions show significantly higher anodic and cathodic currents for more acidic solutions due to the instability of the passive oxide film of aluminum. This film is stable in near-neutral solutions and unstable in highly acidic solutions. As a result, the breakdown of the passive film increases the effective area contributing to anodic or cathodic currents resulting in enhanced local corrosion.

The series of experimental results show that galvanic interaction leads to a decrease of pH at the aluminum anode, and therefore increasing local corrosion of the aluminum surface. The increase of local corrosion induced in a galvanic couple depends on the cathode material and underlines the importance of accounting for local corrosion and pH-dependent corrosion kinetics when predicting the galvanic compatibility of aluminum alloys.
Recent Trends and Challenges of Automated Disassembly for Electric Vehicle Batteries
Authors: Harter Jonathan
Published: December 2024

As electric vehicle (EV) technology continues to advance, the circularity and identification of key failure mechanisms of battery packs are of major concern. This discussion introduces a novel technology designed to characterize batteries at the pack level and identify failing cells within EV battery building blocks such as sections, modules, and cells. Leveraging advancements in machine learning, sensor technology, and data analytics, this innovative approach offers a comprehensive solution for early detection and serviceability for EV battery packs. Preventing premature discarding of valuable, high integrity, components of EV batteries is one of many methods to improve economics of end-of-life batteries and extending the useful life of critical material containing systems. In this discussion, I will highlight the challenges associated with automated disassembly of EV packs as well as give insights into new strategies to achieve automation of these processes. I will discuss initial results from a technology that utilizes high-resolution electrochemical data collected at the cell level within the battery pack to identify compromised cells to aid disassembly processes. This may be achieved by processing the data through sophisticated algorithms capable of detecting subtle deviations from expected behavior (healthy electrochemical characteristics), indicative of cell degradation or impending failure.
Changes in Properties of Superalloy Powder According to Changes in Gas Spray Process Parameters
Authors: Lee HAN Chan , Son Myeong Kyun , Kim Keun Hwan , Ham Sol , Kim Da Jeong , Choi Sun ho
Published: December 2024

In this study, we investigated the production of Ni-based superalloy powder to repair turbine blades in gas turbines by 3D printing. The alloy powder was produced using gas atomization, and we investigated changes in the properties of the powder by varying the molten metal flow rate, orifice design, and gas injection nozzle to control the yield, particle size, and shape. The particle size and shape of the produced alloy powder were analyzed using a Particle Size Analyzer (PSA) and Scanning Electron Microscope (SEM). Additionally, Inductively Coupled Plasma (ICP) and Oxygen-Nitrogen-Hydrogen (ONH) analyses were conducted to verify the powder's composition and the levels of oxygen and nitrogen. The study found that using an orifice with an inner diameter of ∅6 mm and a tip angle of 32° at an injection pressure of 45 bar improved the yield of powder manufacturing. Furthermore, replacing a nozzle from 2 holes to 4 holes led to higher and more uniform production of alloy powder, enhancing the existing fuel and pressure system.
Highly Safe and Fast Charing Method Based on Electrochemical Thermal Life Model for Lithium Ion Battery
Authors: Yu Kyungjin , Adeyinka Adekanmi M. , Du Xiaoniu , Choe Song-Yul , Lee Wooju
Published: December 2024

Long charging time is one of the technical barriers that should be overcome for the wide acceptance of electric vehicles (EVs) in the market. The charging time can be simply reduced by an increased charging current that adversely reduces lifespan and deteriorates the safety of batteries. Therefore, the design of an appropriate charging protocol is a challenging issue. We have developed a fast charging method based on a reduced order electrochemical life model (ROM) considering side reactions and lithium plating. Among different fast charging profiles, the negative pulse (NP) charging method is selected. The pulse discharging current between high charging currents can promote lithium stripping so that lithium ions can be recovered from the plated lithium. The fast charging currents are optimized using a nonlinear model predictive control (NMPC) algorithm. The objectives are set to reduce the charging time with minimized degradation speed. Multiple constraints are considered in NMPC such as state of charge, cutoff voltage, side reaction rate, anode potential, and ion concentrations. The proposed fast charging algorithm is tested in real-time using a Battery-In-the-Loop (BIL) system. The results have shown that the charging time can be reduced while degradation rate can be maintained compared with the normal charging method.

Reference

[1] Yin Y., Bi Y., Hu Y., Choe, S. Y. (2021). Optimal Fast Charging Method for a Large-Format Lithium-Ion Battery Based on Nonlinear Model Predictive Control and Reduced Order Electrochemical Model. Journal of The Electrochemical Society, 167, 160559

[2] Yin Y., and Choe, S. Y. (2020). Actively temperature controlled health-aware fast charging method for lithium-ion battery using nonlinear model predictive control. Applied Energy, 271, 115232.

[3] Song M., Choi M., and Choe, S. Y. (2023). Start-Up Charging Strategy for a Large-Format NMCA/Graphite Pouch Cell from Subzero Temperature Using an Electrochemical, Thermal, and Mechanical Life Model. Journal of The Electrochemical Society, 170, 060533

[4] Song M., and Choe, S. Y. (2019). Fast and safe charging method suppressing side reaction and lithium deposition reaction in lithium ion battery. Journal of Power Sources, 436, 226835
(Keynote) Discovery and Progress of Solid State Perovskite Solar Cells
Authors: Park Nam-Gyu
Published: December 2024

Since the groundbreaking report in 2012 demonstrating the 9.7% efficient and 500-hour stable solid-state perovskite solar cell (PSC) based on methylammonium lead iodide, the power conversion efficiency (PCE) has rapidly increased to 26.1%. This remarkable progress can be attributed to the defect-tolerant nature of halide perovskite combined with a high absorption coefficient. The subsequent development of PSC-employed tandem solar cells reached an impressive PCE of 33.9%, marking a promising step towards the commercialization of PSCs. However, challenges persist, particularly in achieving robust stability, especially concerning light stability during light soaking and thermal stability exceeding 85°C. Two common types of PSCs, namely n-i-p and p-i-n structures, exhibit differing stability characteristics, with indications that the p-i-n type may offer superior stability compared to the n-i-p type. Nevertheless, the efficiency of p-i-n PSCs falls short of that achieved by n-i-p PSCs. In this presentation, discovery of the solid state PSC will be briefly introduced, which is followed by addressing topics for the future research directions, including methodologies for higher PCEs, better stability, synthesis of low-cost precursor materials and lead immobilization.
A Recyclable Reducing Agent to Minimize Sn4+ in Pb-Sn Mixed Perovskite Precursor Solution for Sustainable All-Perovskite Tandem Solar Cells
Authors: Passarut Boonmongkolras , Yang Sung Woong , Kim Sunwoo , Yun Jungchul , Yun Yeonghun , Seo You-Hyun , Jeon Nam Joong , Han Gill Sang , Im Doyun , Lee Sangwook
Published: December 2024

With the increasing demand of high efficiency solar cells, all-perovskite tandem solar cells have spotlighted. However, power conversion efficiency (PCE) of all-perovskite tandem solar cells suffer from the charge carrier losses of Pb-Sn perovskite, which are induced from the Sn2+ oxidation. In this report, we introduce metallic Ni as a sustainable reducing agent for Pb-Sn mixed perovskites. Metallic Ni can effectively reduce the oxidized Sn4+ in the perovskite precursor solution by oxidizing itself, and the generated Ni2+ did not affect to the perovskite lattice. In addition, by utilizing a simple magnetic filtration system, metallic Ni can remain in the perovskite precursor solution while the precursor solution is using. We also confirmed the availability of recycle of the metallic Ni without any further processing. Single-junction Pb-Sn mixed perovskite solar cells used metallic Ni achieved 22.26% of PCE (aperture size of 0.094 cm2), and 90% of the initial PCE was maintained for 1250 hours. Consequently, all-perovskite tandem solar cells reached to 28.13% of PCE (aperture size of 0.094 cm2), by adopting the metallic Ni as a reducing agent.
(Invited) De-Doping Control Engineering for High Efficent and Stable Perovskite Solar Cells
Authors: Kim Dong Suk , Shin Yun Seop
Published: December 2024

The use of 2,2’,7,7’-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (spiro-OMeTAD) as a hole transfer layer (HTL) in normal n-i-p type perovskite solar cells (PSCs) has been pivotal since their inception in 2009, sparking extensive research. To advance towards commercial viability, PSCs must endure rigorous stability tests, including exposure to extreme conditions. Achieving stability under harsh temperatures exceeding 85 ℃ remains challenging. Here, we unveil the pivotal role of effectively optimizing quantity of additives to minimize the de-doping process, a crucial factor impacting the efficiency of PSCs. The optimization of spiro-OMeTAD additives enables changes in the morphology deformation of the hole transfer layer, fostering relatively ordered structures, stabilized complexes, and a significant rise in the T

g
, > 110 ℃. These results enable the PCE of the PSCs to go over 26%, alongside a resilient operational thermal stability of 85 ℃ over 1000 hours, demonstrating its suitability for commercialized PSCs.
(Invited) Ultrathin Polymer Insulating Layers By Initiated Chemical Vapor Deposition for Low-Power Soft Electronics
Authors: Im Sung Gap
Published: December 2024

Insulating layers based on oxides and nitrides provide high capacitance, low leakage, high breakdown field and resistance to electrical stresses when used in electronic devices based on rigid substrates. However, their typically high process temperatures and brittleness make it difficult to achieve similar performance in flexible or organic electronics. Here, we show that poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane) (pV3D3) prepared via a one-step, solvent-free technique called initiated chemical vapour deposition (iCVD) is a versatile polymeric insulating layer that meets a wide range of requirements for next-generation electronic devices. Highly uniform and pure ultrathin films of pV3D3 with excellent insulating properties, a large energy gap (>8 eV), tunnelling-limited leakage characteristics and resistance to a tensile strain of up to 4% are demonstrated. The low process temperature, surface-growth character, and solvent-free nature of the iCVD process enable pV3D3 to be grown conformally on plastic substrates to yield flexible field-effect transistors as well as on a variety of channel layers, including organics, oxides, and graphene. In this presentation, we will review the advantageous characteristics of iCVD gate dielectric layers for soft electronics and their various device applications.
(Invited) Influence of Very Low Energy Ions on Monolayer Graphene: An Experimental and Theoretical Investigation
Authors: Vinchon Pierre , Miyamoto Yoshiyuki , Hamaguchi Satoshi
Published: December 2024

With the ever-decrease in semiconductor device dimensions, a precise understanding of plasma-surface interactions becomes crucial. It is especially necessary to study how low-pressure plasma can generate surface defects even if its ion impact energy is sufficiently low. Upon contact with the sample, plasma-excited species induce out-of-equilibrium phenomena on surfaces, whose influences are difficult to quantify. Furthermore, synergistic phenomena can arise with simultaneous irradiation of the sample by other plasma-excited species such as metastable and VUV photons. These effects are often invoked but rarely understood. As a result, a mechanistic understanding of plasma-surface interactions involving all excited species remains a challenge.

It has been shown that low-pressure argon plasma irradiation of graphene induces a significant amount of defects even with ultralow energy ions (~12 eV). This is even more remarkable considering that the threshold energy to generate defects in graphene is well established at 18-22 eV [1]. There is reason to believe that ion neutralization to the surface may also contribute to the defect generation of graphene [2]. On the other hand, argon metastable influence, often overlooked for 3D material treatments, has been observed to have a non-negligible influence on graphene, promoting vacancy migration and nucleation [3]. Both ions and metastables are suspected to generate transient hot electrons and holes in graphene, leading to out-of-equilibrium surface physics.

We will present how numerical simulations can support experiments of plasma-graphene interaction, which enables a better understanding of the mechanisms of graphene surface dynamics under extreme conditions. However, the standard classical Molecular Dynamics (MD) simulation is typically applicable only to charge-neutral or constant-charge systems. Since ion neutralization involves electron dynamics, it is necessary to use first principles simulations such as Time Dependence Density Functional Theory (TD-DFT). Coupled with MD, TD-DFT simulation can provide insight into electron energy and density influence on the graphene defect generation. More generally, a study coupling experiments and numerical simulations for monolayer graphene can benefit other plasma processes requiring atomic-scale control.

[1] F. Banhart, J. Kotakoski, and A. V. Krasheninnikov, Structural Defects in Graphene, ACS Nano 5, 26 (2011).

[2] P. Vinchon, X. Glad, G. Robert Bigras, R. Martel, and L. Stafford, Preferential Self-Healing at Grain Boundaries in Plasma-Treated Graphene, Nat Mater 20, 49 (2021).

[3] P. Vinchon, X. Glad, G. R. Bigras, A. Sarkissian, R. Martel, and L. Stafford, Plasma–Graphene Interactions: Combined Effects of Positive Ions, Vacuum-Ultraviolet Photons, and Metastable Species, Journal of Physics D: Applied Physics 54, 295202 (2021).
Plasma Etch of IGZO Thin Film and IGZO/SiO2 Interface Diffusion in Inductively Coupled CH4/Ar Plasmas
Authors: Li Jie , Souriau Laurent , Kundu Shreya , Bezard Philippe , Lazzarino Frederic
Published: December 2024

InGaZnO (IGZO) has recently gained considerable attention as a promising alternative channel material for semiconductor devices. Thoroughly investigating and precisely controlling the manufacturing processes, including plasma etching of IGZO material, become essential for the fabrication of IGZO-channel devices. In this work the etching characteristics of IGZO thin films were systemically investigated in inductively coupled CH4/Ar plasmas with various gas ratios, bias voltages, and surface temperatures. The ion flux in CH4/Ar plasmas were analyzed using bias power and voltage, and the relative densities of CH and H radicals were quantified through optical actinometry. The change in the density of CH3 radicals, considered as the primary etchant, is also estimated based on plasma kinetics analysis. O2 plasma step was applied after CH4/Ar plasma to mitigate hydrocarbon deposition during CH4/Ar plasma processing. At low CH4 ratios the IGZO etch rate increases with a higher CH4 proportion, aligning with the ascending trend of CH3 radical density, which suggests that CH3 radical density acts as a limiting factor (radical-limited regime). However, IGZO etch rate decreases at high CH4 ratios, corresponding to the reduction in ion flux, which indicates that ion flux becomes a limiting factor in this ion-limited regime. IGZO etch rate shows a linear relationship with bias voltage and follows the Arrhenius equation with varying surface temperature in plasmas without bias voltage. A spontaneous etch rate model was proposed for radical-limited etch regime. In this model, the etch rate is determined by CH3 radical density and IGZO surface reactivity, where both ion energy and surface temperature play important roles. IGZO thin film was deposited on SiO2 during the fabrication of a three-dimensional ferroelectric field-effect transistor (FerroFET) device, and the interaction between IGZO and SiO2 in CH4/Ar plasmas was investigated using time-of-flight secondary ion mass spectrometry. The efficacy of removing IGZO atoms that had diffused into the below SiO2 network was enhanced when subjected to CH4/Ar plasma with a bias voltage compared to the process without bias voltage. However, exposure to CH4/Ar plasma resulted in a deeper diffusion of IGZO atoms into SiO2 network, primarily attributed to ion bombardment rather than elevated surface temperature. A significant improvement in surface smoothness was achieved after IGZO and SiO2 etch by introducing BCl3 into the SiO2 etching chemistry.
Novel Multilevel Memory Behavior of CsPbBr3 perovskite Nanocrystals with Assistance of High Performance 2D MoS2 channel
Authors: Chen-Yu Tsai , Lu Ming-Pei , Lu Ming-Yen
Published: December 2024

The photo-memory functions as a non-volatile floating gate photo-memory (FGPM) by utilizing light-induced electron generation and subsequent storage in the floating layer. This design effectively mitigates the problem of vertical leakage current and the utilization of lasers can result in electrons being produced at faster write speeds. This study presents the demonstration of a FGPM utilizing oligomeric silica-coated CsPbBr3 perovskite nanocrystals as the active layer. The configuration of FGPM device is shown in Figure 1a, with high mobility MoS2 to facilitate efficient charge transfer from the active layer and minimize recombination. In our study, the optical properties of CsPbBr3 (Figure 1b) exhibits the sharp emission peak at 530 nm and the absorption edge around 540 nm. Moreover, TEM image of CsPbBr3 in Figure 1c reveals the nanocubes with high crystallinity, the size is uniformly distributed around 8 nm. After incorporating with MoS2 flake, the FGPM device shows the favorable characteristics associated with transistor behavior with the on/off ratio of 103. Moreover, in the presence of laser illumination, a noticeable shift in the threshold voltage is attributed to the trapping of electrons in the hybrid layer. The storage of multi-bits is accomplished through the manipulation of laser wavelength, power and the duration of illumination. In addition, the utilization of a laser enables the attainment of multi-bits memory, thereby enhancing data storage capabilities. Consequently, the well designed device in the present study has the potential to significantly enhance the performance of FGPM in addressing the growing demand for storage.

Figure 1
CMOS-Compatible Ultra-Low-Current Electrochemical Random-Access Memory Having Ruthenium Oxide Reservoir for Analog in-Memory Computing
Authors: Kim Jae Kyeong , Woo Dae-Seong , Park Gwang-Ho , Shim Tae-Hun , Park Jinsub , Park Jea-Gun
Published: December 2024

Memristive devices with a two-terminal structure have been suffered an intrinsic read disturbance problem in which stored data (i.e., conductance) changes during the inference process of a deep learning accelerator due to identical read and write paths1. Thereby, the recognition accuracy of a deep learning accelerator can be remarkably degraded. To solve this issue, the light element ions-based (i.e., Li or H) or metal oxide-based electrochemical random-access memory (ECRAM) with a three-terminal structure has been reported to be capable of separating read and write processes2-4. However, Li or H ion-based ECRAM are not compatible with CMOS process because light elements ions (Li or H) cannot be controlled due to generation of undesirable diffusion at high temperatures. In addition, a high energy efficiency in cross-point arrays using the metal-oxide-based ECRAM cannot be obtained due to its high operating current.

In this study, for the first time, we report an ultra-low-current ECRAM utilizing ruthenium oxide-based reservoir layer for analog in-memory computing. The proposed ruthenium oxide reservoir-based ECRAM demonstrated an ultra-low-current of ~300 nA during write process at a gate amplitude of 5V. In addition, the ruthenium oxide reservoir-based ECRAM exhibited the gate-tunable synaptic plasticity (i.e., long-term potentiation and long-term depression) by varying the pulse width of the gate bias. Moreover, we investigated the gate polarity-induced migration of Ru ions via time-of-flight secondary ion mass spectrometry analysis. Finally, we designed convolutional neural networks (i.e., LeNet-5) using the TensorFlow and Keras frameworks in Python environments and achieved a classification accuracy of 98.58 % in the image recognition task. We present in detail about the mechanism of ultra-low-current ECRAM and its application.
Structural and Electrical Properties of (1-x)Pb(Zr, Ti)O3-Xpb(Zn0.4Ni0.6)1/3Nb2/3O3 Piezoceramics with R-PC-T Multistructure
Authors: Lee Geun-Soo , Kim Jung-Soo , Kwak San , Nahm Sahn
Published: December 2024

The structural and electrical properties of (1-x)Pb(Zr1-zTiz)O3-xPb(Zn0.4Ni0.6)1/3Nb2/3O3[(1-x)P(Z1-zTz)-xPZNN] piezoceramics have been systematically investigated to identify compositions exhibiting the rhombohedral-pseudocubic-tetragonal (R-PC-T) multistructure. Rietveld refinement reveals that the pseudocubic (PC) structure observed in the (1-x)P(Z1-zTz)-xPZNN piezoceramics is very similar to the Pm3m cubic structure. However, the PC structure cannot be a cubic structure because the (1-x)P(Z1-zTz)-xPZNN piezoceramics with the PC structure exhibit ferroelectric and piezoelectric properties. The R-PC-T multistructure was identified in the (1-x)P(Z1-zTz)-xPZNN piezoceramics (0.335 ≤ x ≤ 0.44) with different z values and the compositions with the R-PC-T multistructure have been suggested. The piezoceramics with the R-PC-T multistructure typically exhibit excellent piezoelectric properties with a high TC. Particularly, the 0.58P(Z0.41T0.59)-0.42PZNN piezoceramic (x = 0.42 and z = 0.59) shows the large d33 of 825 pC/N, kp of 0.7 and strain of 0.185 % at 3.0 kV/mm with a high TC of 240 oC.
Stabilizing P-Doped Radical Via De-Doping Control for Highly Efficient and Thermal-Stable Perovskite Solar Cells
Authors: Shin Yun Seop , Kim Dong Suk
Published: December 2024

In conventional n-i-p perovskite solar cells, unsolved issues persist, especially with regards to their notorious performance degradation under prolonged heat exposure at 85 ℃. Poor device stability arises from the presence of large amounts of additives in the widely used hole-transporting layer (HTL), spiro-OMeTAD, causing its glass transition temperature (T
g) to drop below 80 ℃. By reducing the concentration of 4-tert-butylpyridine (tBP) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and adjusting their molar ratio to one, we achieved a dramatic increase in the heat stability of the PSC, while boosting its power conversion efficiency (PCE). The formation of a 1:1 tBP–Li+ complex was found to be crucial for preventing the presence of free tBP molecules in the hole conductor formulation. This suppressed the de-doping of the p-type spiro-HTL by tBP, and its deleterious ingression into the perovskite film as well as the release of tBP vapor under heat stress. We observed an increase in the p-doping efficiency, which boosted the electrical conductivity of the HTL while improving its energy alignment with the valence band of the perovskite. At the same time, the T
g of the HTL was raised to 105 ℃ greatly improving its thermal stability. As a result, the PSCs accomplished a PCE of 26.18% (certified 26.00%) while demonstrating remarkable resilience to prolonged heat exposure at 85 ℃. Furthermore, a perovskite solar mini-module with an aperture area of 25 cm2 achieved a PCE of 23.29%.
(Invited) Advanced Insitu Electron Microscopy for Batteries: Insights for Lithium-Ion and Beyond
Authors: He Kai
Published: December 2024

Rechargeable batteries are crucial for energy storage across consumer electronics and automobile propulsion applications, facilitating the transition towards carbon neutrality and advancing clean energy technologies. Despite great success of Li-ion batteries (LIBs) in the commercial market, alternative technologies based on beyond-Li chemistry are highly demanded for large-scale and power-intensive applications necessitating enhanced energy density, lifetime, and safety, where fundamental understanding of the structure-property relationship of novel battery materials is critically needed. Transmission electron microscopy (TEM) is an indispensable method to characterize materials structures and compositions at the atomic scale, which is of particular importance for battery research to investigate crystal lattices, defects, as well as microstructural and chemical heterogeneities within materials used in electrodes, electrolytes, and their interfaces. Further, with rapid technical development, in-situ TEM has enabled real-time observations of various dynamical phenomena and chemical processes during battery cycling and phase transformations. Leveraging advanced in-situ TEM techniques, our collaborative endeavors with Dr. Marca Doeff have enabled us to conduct comparative analyses of Li and Na reactions within battery electrodes, offering unique insights into in early-stage beyond-Li chemistry. Herein, we present a systematic exploration of in-situ TEM studies for LIBs and beyond, focusing on electrode materials through intercalation, alloying, and conversion reaction mechanisms. By direct comparison between electrochemical reactions with Li and Na, we found substantial differences in reaction mechanisms, pathways, and kinetics between lithiation and sodiation processes, which are fundamentally related to various factors, such as ionic diffusion barrier, electrochemically induced stress, and geometric constraints. This concept has been demonstrated in multiple case studies that allows us to enhance the sodiation kinetics by tuning the overall reaction energetics through nanostructure optimization and interfacial engineering. We envision that the knowledge learned from in-situ TEM will provide valuable insights into understanding the alkali-ion electrochemistry and kinetics, thereby serving as foundational principles guiding the advancement of beyond Li-ion battery technologies.
Dcir for in-Situ Analysis of Li-NMC Batteries
Authors: Lochala Joshua , Anderson Cassidy , Baar Kevin
Published: December 2024

This research delves into the qualitative analysis of internal processes in lithium nickel manganese cobalt oxide (Li-NMC) batteries by utilizing direct current (DC) techniques throughout the battery's lifecycle. Expanding on the comparative approach between electrochemical impedance spectroscopy (EIS) and DC techniques highlighted by Martin Winter1, this study emphasizes the exclusive application of DC techniques for an in-situ understanding of battery behavior without the potentially performance-impacting application of EIS. By systematically measuring resistance changes, this work uncovers the effects of lithium coatings, electrode thickness variations, and the operation of anode-free batteries on the internal resistance profiles. The methodology provides a non-invasive insight into the electrochemical dynamics, enabling a deeper understanding of the material and design factors that influence battery efficiency and longevity. Utilizing the information imbedded within the electrochemical data the plating overpotential which translates into the ohmic resistance, a pattern is seen connect the ohmic resistance to that of cycle stability. Understanding the resistance helps to identify characteristics that have been previously hidden without intrusive testing.

L. Stolz, M. Gaberšček, M. Winter and J. Kasnatscheew, Chemistry of Materials, 2022, 34, 10272-10278.