bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Fundamental Understanding of Si-Based Anodes Using Carboxymethyl Cellulose (CMC) and Styrene-Butadiene Rubber (SBR) Binder for High Energy Lithium Ion Battery Applications
Authors: Kumar Kuldeep , Matts Ian L , Klementov Andrei , Sisco Scott , Simpson Dennis A. , Millero Edward R. , Kaleem Kareem , Terrago Gina M. , Lee Se Ryeon
Published: July 2022

With increasing demand of high energy density lithium ion batteries, silicon (Si) based anodes are an obvious substitute of graphite based systems due to their high capacity. However, large volume changes of Si during lithiation and delithiation processes causes pulverization of silicon particles. The resulting reduction in electrical continuity and solid electrolyte interphase (SEI) growth within the anode leads to a fast depletion of lithium reservoirs and an accelerates battery failure. High energy lithium ion battery applications such as electrical vehicles and electronic devices require high capacity retention over extended cycling, so improving performance of Si-based anodes is a critical need for many applications.

Commonly, a combination of sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) is used as a binder for waterborne Si anode slurries. In these systems, carboxyl (-COOH) groups on CMC form chemical bonding with hydroxyl (-OH) groups on Si active material surface and SBR addition provides enhanced flexibility in the anode layer. Several reports on electrode integrity improvement through adhesion promoters, increased crosslinking, different binding groups, etc. are available in the literature. Delving deeper into the weak mechanical integrity of Si based anodes, and understanding the parameters influencing the fabrication process and subsequent properties, is important. This presentation will focus on several variations in Si based anode slurries and electrodes using CMC-SBR binders. Physical, mechanical, and electrochemical properties are extensively studied as a function of these parameters and will be discussed.
3D Printing of Silicon-Based Anodes for Lithium-Ion Batteries
Authors: Rist Ulrich , Sterzl Yannic , Pfleging Wilhelm
Published: July 2022

In order to meet the target for the next generation lithium-ion batteries, electrochemical performance such as energy and power density must be increased significantly at the same time. Optimized electrode architectures including 3D battery concepts and advanced materials are in development to achieve this goal. The use of silicon-graphite composite electrodes instead of graphite anodes is currently investigated. This is due to the fact that silicon can provide almost one order of magnitude higher specific energy density (3579 mAh/g) in comparison to natural graphite (330 - 372 mAh/g). However, during lithiation, i.e., lithium silicide formation, a volume expansion of about 300 % can take place, while during lithium intercalation in graphite about 10 % volume expansion can be observed. A huge volume expansion leads to a tremendous mechanical degradation of the anode resulting in a drop in capacity, and a limited battery lifetime.

In the presented study, laser induced forward transfer (LIFT) is applied as printing technology to develop sophisticated graphite and graphite-silicon electrode architectures with advanced electrochemical performances. LIFT was performed using a pulsed nanosecond UV laser with a repetition rate of up to 30 kHz and a maximal power of 10 W. To enable an accurate printing process during LIFT, the properties and compositions of the active material inks as well as the laser and process parameters have to be optimized. The printing process in combination with laser structuring provides a high flexibility regarding the final electrode design. In the presented study, the formation of multi-layer electrodes with spatial variation in electrode composition is achieved. As active materials silicon nanoparticles (SNPs) and various types of graphite, i.e., natural graphite, mesocarbon microbeads (MCMB), and artificial flake-like graphite with an average particle diameter of 1 µm up to 15 µm are utilized. The geometry and thickness of each printed layer is adapted with regard to an optimized electrochemical performance and cell lifetime. A single layer thickness of 5 µm up to 20 µm was achieved, while areal capacities of multi-layer anodes reaches values of 2 to 4 mAh/cm². In addition to the applied active materials and architecture concepts, different solvent and binder systems are investigated with regard to process scalability and an improved environmental compatibility. The printed electrodes are electrochemically characterized by rate capability measurements at C-rates of up to 5C. A correlation between capacity retention and electrode architecture is achieved. The results are discussed in terms of upscaling and impact on the next generation anode material.
Optimal Charging Protocols to Restrict Lithium-Ion Battery Degradation
Authors: Uppaluri Maitri , Kolluri Suryanarayana , Subramanian Venkat R.
Published: July 2022

Lithium-ion batteries degrade due to several mechanisms that occur during cell operation. These mechanisms can be parasitic reactions that lead to loss of lithium inventory or loss of active material. Some examples of these side reactions include the growth of the solid-electrolyte interphase (SEI) layer, transition metal dissolution and deposition, lithium plating, solvent oxidation, etc. Thermal effects and mechanical fatigue on the electrodes also lead to cell aging and capacity fade.

For widespread implementation of lithium-ion batteries for electric vehicles, batteries should last approximately 10 years.1 Fast charging has also been heavily researched for accelerating this prevalent circumstance. However, charging at high currents can severely degrade the cell, affecting the cell’s lifetime. Algorithms that optimize charging can be effective to reduce cell aging. Physics-based battery models can be used to design these algorithms by restricting phenomena that occur in the cell that causes cell aging. For example, lithium plating can be prevented by restricting the overpotential of the reaction.

In our previous work, we have shown optimal charging profiles where the intercalation induced stresses, lithium plating and the SEI layer growth was restricted using reformulated physics-based models using model-based control 2
-
3 In this talk, we show different optimal charging protocols for restricting different mechanisms, and analyze the interplay between them to predict optimal charging profiles.

References

M. T. Lawder, P. W. C. Northrop, and V. R. Subramanian, J. Electrochem. Soc., 161, A2099–A2108 (2014).

B. Suthar, P. W. C. Northrop, R. D. Braatz, and V. R. Subramaniand, J. Electrochem. Soc., 161, F3144–F3155 (2014).

M. Pathak, D. Sonawane, S. Santhanagopalan, R. D. Braatz, and V. R. Subramanian, ECS Trans., 75, 51–75 (2017).
(Digital Presentation) Parameterization of a Commercial 18650 High-Power Lithium-Ion Cell for a Physico-Chemical Model
Authors: Ahamad Salahuddin , Sundaramaan K. V. , Singh Parmender
Published: July 2022

Li-ion battery is an integral part for the electric or hybrid electric vehicles, as they provide high energy density and power density with extended cycle-life compared to their closest rivals, Ni-MH batteries [1]. Electric vehicles (EVs) require an advanced real-time based battery management system (BMS) that ensure a safe and efficient energy utilization, estimate state-of-charge (SOC) and state-of-health (SOH), and cell balancing [1]. A high performing BMS needs an accurate cell model that can precisely capture the cell dynamics in EVs. Due to the inherent complexity of the physics-based model, BMS are often based on equivalent circuit models [2-4] that are relatively easy to implement but lack the important underlying physico-chemical processes. In order to predicts an accurate cell response, a physico-chemical model based on fundamental governing equations of migration and diffusion processes as well as the kinetics of intercalation require precisely evaluated model parameters for the material under consideration [5].

In this work, a commercial 18650 cell is analyzed in order to parameterize a physico-chemical model. The parameters are estimated by the results of experiments performed on the cell material under investigation. For this, the fully discharged cell was opened in a glove box under inert environment with both moisture and oxygen level below 0.5 ppm. The material samples were collected in an air tight desiccator and analyzed using different methodology.

The results obtained based on the proposed methodology are presented as: electrodes, electrolyte, and separator composition; kinetic, transport, and thermodynamics parameters; electrodes and separator physical properties, e.g., porosity, microstructure, particle size distribution etc.; cell internal configuration, e.g., jelly roll dimension, electrode tab location and their dimension etc.; and full-cell electrode balancing determination. A range of electrochemical techniques were used to determine the kinetic and thermodynamic properties of the electrode materials, e.g., galvanostatic intermittent titration technique (GITT) was used to estimate the diffusion coefficient of Li-ion in anode and cathode at different state of charge (SOC) also, to ascertain the open circuit voltage (OCV) of the respective electrodes. In order to estimate the exchange current density, electrochemical impedance spectroscopy (EIS) was employed. The SEM images to illustrate the microstructures of cathode, anode and separator and the particle size distribution of cathode and anode are shown in Figure.

References:

D. Rahn, and C. Y. Wang, Battery Systems Engineering, Wiley, State College, PA (2013).

L. Plett, J. Power Sources, 134, 252 (2004).

W. Verbrugge, and R. S. Conell, J. Electrochem. Soc., 149, A45 (2002).

L. Moss, G. Au, E. J. Plichta, and J. P. Zheng, J. Electrochem. Soc., 155, A986 (2008).

S. Ahamad, and A. Gupta, Electrochim. Acta, 297, 916 (2019).

Figure 1
Automated Data Gathering, Classification, Standardization and Evaluation Connected with AI in Smart Li-ion Battery Cell Production
Authors: Hagen Markus , Ngyuen Josef Quan , Lau David Hui Shyan , Nave Eran , Tübke Jens
Published: July 2022

The production of lithium-ion batteries is characterized by high scrap rates. With material costs of 70-80% of the cell price, these are a significant cost factor. By using AI, correlations of process data and cell properties can be determined and particularly quality-relevant process steps can be identified.

However, the prerequisite for the use of AI is a clean collection, description and allocation of data which is very time-consuming.

In the BMBF-funded projects “KontElPro”, for solvent-free electrode production and “AgiloBat2”, for the agile production of format-flexible cells, software is being developed to solve this problem.

The corresponding software system "Batalyse" is capable of automatically collecting, categorizing, linking and evaluating test, analysis and production data. Quality-relevant parameters of the produced (lab) cells such as capacity, resistance and power can thus be directly correlated with process parameters and data. The complete process chain of input materials, (intermediate) products, sensors, equipment, process parameters and all evaluated result data of the produced cells is stored in the database. All data, correlations and logic is provided by this database via an interface for AI applications.

The aim is to use this data to generate digital twins of each individual process step and to optimize them step by step. Later, the processes are to be controlled autonomously by AI applying optimized process parameters to avoid or at least to reduce scrap.

In the talk we present the structure, status and use of the software for research data management and in the use of in the research production of Li-ion cells.
Conversion of Carbon Dioxide into Value Added Chemicals Using Electrochemical Reduction Method on Supported Bimetallic Catalysts
Authors: Birhanu Mulatu Kassie
Published: July 2022

Currently, many studies reveal that the level of carbon dioxide in the atmosphere is rising continuously and disrupt the environment due to its cause for global warming. For this reason, advanced and emerging technologies associated with conversion of CO2 are highly essential. Among many of the methods, electrocatalytic reduction of CO2 is the most efficient and easy way to reduce CO2 into CO, alcohols, hydrocarbons and other products. Bimetallic nanoparticles of Au and Cu and the parent monometallics of each metal are synthesized and supported on functionalized multiwalled carbon nanotubes (MWCNT). The supported bimetallic nanoparticles are dispersed uniformly on fiber carbon papers (CP). To evaluate and correlate the performance of the reduction, tuning the size and structural properties of AuCu electrocatalyst are investigated by incorporating polyvinylpyrrolidone (PVP) for electrochemical reduction (ECR) of CO2. Different amounts of PVP are applicable for each bimetallic and monometallic electrocatalysts (AuCu/MWCNT/CP, Au/MWCNT/CP and Cu/MWCNT/CP). The significant role of PVP on the atomic distribution of AuCu nanoparticles (NPs) and its particle size have been studied in advance. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) are key measurements to estimate the alloying extent of Au Cu in the alloy including the coordination numbers of each metal. The electrocatalysts, which are prepared with PVP, have a better activity and selectivity compared to the bimetallic synthesized without PVP. The amount of PVP affects the structure and significantly minimizes the size of NPs that influences the activity and selectivity of products. At -0.91 V vs. RHE, the faradaic efficiency (FE%) of CO using AuCu/CNT (1.5 g PVP) was around 88%, but in the absence of PVP, the same test resulted in ~71%, indicating the effect of PVP in the product selectivity.
Characterization of Interfacial Properties in Electrochemical Nitrate Reduction to Optimize Ammonia Production
Authors: Guo Jinyu , Corson Elizabeth R. , Tarpeh William Abraham
Published: July 2022

Nitrate pollution of wastewater from agricultural runoff and industrial waste streams is common around the globe. Nitrate negatively impacts the environment through harmful algal blooms and can be dangerous for human consumption. Rather than treat nitrate as a waste, we electrochemically reduce nitrate (NO3RR) to ammonia (NO3
- + 9H+ + 8e- → NH3 + 3H2O), a commonly used fertilizer and clean fuel. Electrochemical treatment can enable on-site, modular treatment powered by renewable energy. As an inner-sphere reaction involving multiple hydrogenation and electron-transfer steps, the activity and selectivity of electrochemical NO3RR to NH3 are strongly influenced by properties at the electrode–electrolyte interface. When potential is applied, the electric double layer (EDL) forms that comprises ordered molecular layers extending up to 10 Å from the surface. This EDL is the primary environment where the heterogeneous NO3RR occurs and can impact the reaction in several ways, including blocking catalytic sites and stabilizing reactants and reaction intermediates. To understand the molecular mechanisms of these impacts, the EDL structure is studied with x-ray reflectivity (XRR), which provides atomic-level resolution of the near-surface electron density profile and reveals the number of ordered layers, the distance of each layer from the surface, the ion surface coverage, and the degree of hydration of ions in each layer. We complement these investigations with operando attenuated total reflectance–surface-enhanced infrared absorption spectroscopy (ATR–SEIRAS) under similar reaction conditions to investigate the adsorbed reactants, intermediates, and local pH. Furthermore, composition and structure of the EDL can change with varying bulk electrolyte compositions and mass transport regimes, which also provide levers to control reaction activity and selectivity. We use a continuum model (generalized modified Poisson–Nernst–Planck, GMPNP) to develop the spatial profiles of the electric field, reactant nitrate concentration, cation concentrations, and pH outside the EDL and how they change as functions of applied potential, bulk electrolyte composition, and flow rate. Taken together, our results relate 1) bulk electrolyte properties with interfacial EDL properties and 2) interfacial properties with reaction activity and selectivity, informing the choice of operating parameters such as electrolyte composition and flow rate to optimize ammonia production in electrochemical NO3RR.
Flow System with Liquid Active Sorbents for Electrochemically Mediated Carbon Capture
Authors: Diederichsen Kyle , Liu Yayuan , Hatton T. Alan
Published: July 2022

Within the field of carbon capture, electrochemically driven methods have drawn increasing attention due to their ability to operate at ambient temperature, their efficient scaling, and potentially low energetic cost. An important consideration in such systems is the method of gas contacting to enable efficient CO2 separation from the feed gas. Previous flow-based electrochemical processes that enable large-area gas contacting and desorption of concentrated CO2 at a point location all utilize water as the solvent and can require significant water feeds due to high evaporation rates. Here, we demonstrate the use of liquid, redox-active sorbents in a flow system that can decouple the electrode size from gas contacting area. The concept sorbent is a nonvolatile, liquid quinone species that can be reversibly reduced and oxidized to capture and release CO2, respectively. In this initial study, we employ the liquid quinone with sodium salts to achieve sorbent capacities near 2.5M CO2 and couple this sorbent to a ferrocene-derived counter electrolyte in a continuous capture – release process. Through this, we illustrate considerations in the salt choice, counter-electrolyte, and system design to best enable this concept sorbent, and discuss many opportunities for future optimizations.
(Invited) Nanoscale Wetting and Its Connection with Macroscopic Young's Equation
Authors: Yamaguchi Yasutaka , Kusudo Hiroki , Bistafa Carlos , Surblys Donatas , Omori Takeshi , Kikugawa Gota
Published: July 2022

Wetting plays a key role in the cleaning process to remove impurities as one of the essential processes for the fabrication of semiconductor device, where cleaning of trenches with water, replacement with IPA (isopropyl-alcohol) and its removal are iteratively carried out. This process is still required upon recent reduction of the line width under 10 nm; however, this size is already at the border of the continuum limit where the theories of fluid mechanics can be applied. The authors adopted molecular dynamics (MD) simulations to examine the liquid behavior, especially regarding wetting at the nanoscale with respect to simple Lennard-Jones fluid [1-3], water [4,5], methanol as well as IPA as the liquids [6,7], while simple non-polar crystal [1-3,6], silica partially terminated with OH as the solids [4,5,7]. In these series of studies, we have shown how the solid-liquid, solid-vapor and liquid-vapor interfacial tensions can be defined in nanoscale to be consistent with Young’s equation as the macroscopic description about wetting.

In the presentation, we will discuss how the interfacial tensions as the free energy can be properly calculated by MD simulations from mechanical and thermodynamic viewpoints.

[1] Y. Yamaguchi, H. Kusudo, D. Surblys, T. Omori and G. Kikugawa, J. Chem. Phys. 150 (2019), 044701.

[2] H. Kusudo, T. Omori, Y. Yamaguchi, J. Chem. Phys. 151 (2019), 154501.

[3] Y. Imaizumi, T. Omori, H. Kusudo, C. Bistafa, Y. Yamaguchi, J. Chem. Phys., 153 (2020), 034701.

[4] D. Surblys, F. Leroy, Y. Yamaguchi, F. Mueller-Plathe, J. Chem. Phys. 148 (2018), 134707.

[5] C. Bistafa, D. Surblys, H. Kusudo, Y. Yamaguchi, J. Chem. Phys., 155 (2021), 064703.

[6] D. Surblys, Y. Yamaguchi, K. Kuroda, M. Kagawa, T. Nakajima, and H. Fujimura, J. Chem. Phys. 140 (2014), 034505.

[7] Y. Yamaguchi, S. Nakaoka, T. Hayashi, M. Kawakami, D. Yano, ECS Trans. 92 (2019), 87.
A Gradual Change in Al1-XScX N Ferroelectric Film upon Switching Reversal
Authors: Tsai Sung-Lin , Hoshii Takuya , Wakabayashi Hitoshi , Tsutsui Kazuo , Kakushima Kuniyuki
Published: July 2022

Ferroelectric materials have been utilized for non-volatile memory applications [1]. Recently, Al1-x
Sc
x
N (ASN) films were reported to exhibit ferroelectricity with a high remnant polarization of over 100 µC/cm2 which is attractive for future non-volatile memory [2]. The feasibility of FeRAM application has been confirmed based on material and electrical properties [3]. One of the issues of ASN films is the lack of reliability and endurance properties, as the number of switching cycles of 104 to 105 is the typical endurance of the ASN films before breakdown [4]. In this study, we infer the gradual change in the ASN film upon switching cycles.

A 50-nm-thick ASN film with x of 0.22 was characterized with TiN electrodes at top and bottom. The as-fabricated film is self-polarized in an upward direction; the negative voltage applied to the top electrode triggers the switching reversal. Capacitance-voltage (C-V) characteristics, double sweeping the voltage to the negative, and then to the positive directions, were used to observe the switching voltage. A sinusoidal wave with an amplitude of 28 V at 2 kHz was used to switch the capacitor, ending with a positive voltage applied to the top electrode.

The C-V curve for the as-fabricated sample (fresh), shown in figure 1, showed only a single peak capacitance for each sweep. The voltage at the peak capacitance during the negative sweep shifted from -20.8 to -17.4 V from the first to third sweep, larger than the shift during the positive sweep. This indicates that the switching voltage, or the coercive field, was reduced during the first negative sweep. After stressing the sample by 103-cycle switching, the C-V curve revealed two capacitance peaks in the negative direction, as shown in figure 2; the peak at -20.2 and -15.2 V are referred to as the peaks obtained in the first and third sweeps for the fresh device. The capacitance peak at -20.2 V gradually decreased moving to merge to the peak at -15.2 V. During this transition, little change of the peak in the positive region was observed, indicating that a gradual transformation in the ASN film upon switching reversal is happening only when the film is switched from upward to downward direction. We hypothesized the creation of nitrogen-vacancy (VN) during the switching, facilitating the movement of N atoms to reduce the coercive field. One can understand that the transformation is completed during the C-V measurement for the fresh sample as the time for the measurement is long.

In conclusion, we observed a gradual change in the switching voltage upon switching reversal. A lower coercive field was found to gradually appear after switching, decreasing, and shifting the initial coercive field.

References

[1] T. S. Böscke, et al., Appl. Phys. Lett., 99, 102903 (2011). [2] S. Fichtner, et al., J. Appl. Phys., 125, 114103 (2019). [3] C. Liu, et al., IEDM Tech. Dig. (2021). [4] S.-L. Tsai, et al., Jpn. J. Appl. Phys. 60, SBBA05 (2021).

Figure 1
(Invited) Breakthrough Avalanche and Short Circuit Robustness in Vertical GaN Power Devices
Authors: Zhang Yuhao , Zhang Ruizhe , Song Qihao , Li Qiang , Liu J.
Published: July 2022

After decades of relentless efforts, GaN power devices, specifically, the lateral GaN high-electron mobility transistor (HEMT), have been commercialized in the 15-650 V classes. Owing to GaN’s competitive physical properties over Si and SiC for power electronics, GaN HEMTs allow for higher switching frequency and therefore, have already seen wide adoptions in fast chargers, wireless charging, data centers, and electrified transportation. Despite the success of lateral GaN HEMTs, a vertical device structure is usually believed to be more favorable for high-voltage, high-power devices. In the last few years, with the advent and maturity of large-diameter, low-dislocation GaN wafers on freestanding GaN substrates, a new generation of vertical GaN power devices have been developed to extend GaN’s application space beyond 650 V. Very recently, several industrial vertical GaN devices in the voltage classes of 1.2-1.7 kV have been demonstrated, which are close to commercialization.

This presentation will review the key advancements in vertical GaN power devices in the past decade, with a focus on the device technologies that are being commercialized, and provide a prospective for research and development in the next decade. The devices to be covered will include two-terminal power rectifiers including the p-n diodes, Schottky barrier diodes, junction barrier Schottky diodes, and trench MIS/MOS barrier Schottky diodes. The transistors will include the trench and planar MOSFETs, current-aperture vertical electron transistors, fin-channel MOSFETs, and fin-channel JFETs. Particular emphasis will be on large-area rectifiers and transistors with a device performance superior to similarly-rated Si and SiC transistors. The newly demonstrated avalanche and short-circuit robustness in vertical GaN devices, which are lacking in lateral GaN HEMTs, as well as their underlying device physics, will also be introduced. The presentation will be concluded by a discussion of current challenges and future application spaces of vertical GaN devices, as well as emerging vertical GaN devices (e.g., superjunction) under development.
Power Cycling Test Failure Analysis of SiC MOSFET Devices
Authors: KIM Mijin , Kang Inho , SEO Jae HWA , Hong Tae-eun , Jeong Jee-Hun , Yoo Dahui , Lee Ho-Jun
Published: July 2022

In recent years, gradual development in industry and automobiles and the field of renewable energy production has been achieved led to significant growth in the field of power semiconductors.

In particular, operation and non-operation are repeated in such a field, so reliability issues such as delamination and cracking are critical factors.

Therefore, there is an increasing demand for reliability verification such as power cycling tests(PCT).

In this study, reliability was evaluated using PCT (Mentor Graphics’ Power Tester 1500A), which repeats the heating and cooling of the device by applying continuous gate pulses in the same way as in the actual operating environment.

Keysight's B1506A was used to compare the electrical characteristics before and after the PCT.

It was found that this increased the turn-on resistance(Ron) on the output curve.

The components of the turn-on resistance are:

Ron = Rpack + Repi + Rch + R*

Where, Rpack is the packaging resistance due to bond wire, metallization, etc., Repi is the drift layer resistor, Rch is the channel resistance, and R* is the other components resistance e.g., the substrate.

If there is an increase of Ron, it might be due to Rpack, which is typical power cycling aging [1].

We also performed Scanning Electron Microscopy (SEM) analysis for failure analysis and confirmed that the bond wire cracked after PCT.

We performed a Scanning Acoustic Microscopy (SAM) analysis for further failure analysis and confirmed that voids were formed in the solder after PCT.

Both results are due, as is previously known, to bond wire degradation resulting from thermal-mechanical stress due to the coefficient of thermal expansion (CTE) mismatch between packaging materials [2].

Figure 1
Vertical Oxide Channel Thin Film Transistor for Ultra-High-Resolution Display
Authors: Lee Sein , Sung Taehoon , Song Min-Kyu , Kwon J.-Y.
Published: July 2022

The significance of backplane devices for ultra-high-resolution (UHR) display has increased with the recent development of augmented reality (AR) and virtual reality (VR) devices. Since the human visual resolution can distinguish up to 60 pixels per degree (PPD), the AR/VR device panel needs at least 3000 pixels per inch (PPI) to exceed the human retina resolution limit for clear display without screen effect. As a results, the unit pixel pitch of thin film transistor (TFT) for UHR display should be not only smaller than a few micrometers (~3 μm), TFT channel length should also be sub-micrometers level. In active matrix organic light emitting diode (AMOLED) display type, self-aligned top gate (SATG) TFT has been widely used as a planar backplane device structure because of its low parasitic capacitance and tolerance of illumination degradation caused by the light from emitting layer [1-2]. However, SATG TFT has fundamental disadvantages for device miniaturization due to its essentially required area of metallization region for reducing contact resistance and scaling limit of channel induced by carrier diffusion shrinking effective channel length. For this reason, we suggested a size tunable oxide channel VTFT structure that can achieve a high pixel density on account of structural benefit on device footprint.

In this work, we fabricated amorphous indium gallium zinc oxide (a-IGZO) based VTFT. The previously published VTFT structure, channel length is determined by the thickness of spacer between source and drain electrodes [3]. Owing to spacer etching process, uneven backchannel roughness and high off current has become well-known issues of VTFT. On the contrary, the proposed VTFT structure has a controllability of effective channel aspect ratio because source and drain electrodes are able to be patterned by photolithography process. Furthermore, the parasitic capacitance is also relatively less than the formerly reported VTFTs controlled by inevitable thickness limit structurally due to the electrodes.

To sum up, we not only realized the oxide channel VTFT that meets high performance for AR/VR display, but opened new application possibility to UHR electronic devices platform.

Figure 1. (a) Schematic of the proposed VTFT (b) Transfer characteristic of VTFT

Acknowledgement

This work was supported by the Korea Evaluation Institute of Industrial Technology(KEIT) grant funded by the Korea government (MOTIE) (No. 2021-11-1283)

References

Kang, Dong Han, et al. "Self-aligned coplanar a-IGZO TFTs and application to high-speed circuits." IEEE electron device letters 32.10 (2011): 1385-1387.

Wang, Guoying, et al. "8.3: High Stability Against Light and Heat Based on the Top Gate Self‐Aligned a‐IGZO TFTs under OLED Dislplay." SID Symposium Digest of Technical Papers. Vol. 49. 2018.

Petti, Luisa, et al. "Flexible quasi-vertical In-Ga-Zn-O thin-film transistor with 300-nm channel length." IEEE Electron Device Letters36.5 (2015): 475-477.

Figure 1
“Presenting of Sound and Non-Sound Waves Signal Analysis “
Authors: Pozinkevych Ruslan
Published: July 2022

Our research is an attempt to derive mathematical formula to describe the state of a system created by to or more waves resulting in a shockwave production

The shockwave produced is a carrier of an energy that can be used for motion in gases and liquids

To be able to utilize this energy we must be able to describe the state of a system of two or more waves at any given time thus deriving a formula that links energy produced to the component characteristics of the wave e.g frequency amplitude etc

A mathematical model is used which presents a system of waves as a sum or difference of two vectors which is the resulting vector or a shockwave It is a model that has been obtained after using detailed analysis of both longitudinal and transverse waves

To simplify the description we are going to look at the waves purely as a carrier of an energy that can further be utilized for different purposes and from that standpoint its easier to regard our waves and a resulting shockwave as a vector I am going to try and explain it from the point of view of mathematics

Lets take a look at the sum (difference) of the two vectors The resulting sum (difference) vector is our sought shockwave which in itself is a carrier of energy

In the attachment to my submission I am presenting a f-la of the wave as a carrier of energy

Its a universal approach towards wave analysis and can be applied to different kind of waves acoustic and non acoustic In that sense analysis of the latter fits well into the agenda and will lead to a detailed explanation on how this principle works (pls see the attached file)

Figure 1
(Digital Presentation) Synthesis of Multisize Layered Silica Inverse Opal Photonic Crystals
Authors: Sadat Arabjafari Maliheh , Bayat Farzaneh , Jamshidi-Ghaleh Kazem , Amani-Ghadim Ali Reza , Fatemi Ali , Rasouli Milad
Published: July 2022

Today, human beings have found an increasing need for energy. The ever-increasing effort to shrink information systems at higher speeds has led to the common idea that photons are used as carriers of information instead of electrons. Photonic crystals have a structure whose dielectric constants and refractive indices change alternately in one, two, or three dimensions, which are called one-dimensional, two-dimensional, and three-dimensional photon crystals. Periodicity in the refractive index of the crystal structure causes a photonic bandgap that includes a range of frequencies in which light with a frequency of this range is not allowed to pass the crystal structure and is reflected or absorbed.

In this work, Poly(methyl methacrylate) (PMMA) microspheres of different sizes were first synthesized using the suspension polymerization method. Concentrations of used materials including initializer, monomer, reaction temperature, reaction time, and rotation speed play important roles in determining the final diameter of PMMA microspheres. Then, the vertical deposition method is used for the growth of multi-layered opals of different sizes, one on top of another. On the other hand, inverse opals have porous and organized structures that are made using opals as the template. The method used in this study to make multisize layered inverse opal made of silica is as follows: 1- Fabrication of a uniform layer of polymer microspheres on a glass substrate with a specified size as a colloidal crystal template 2- Infiltration of void space between the microspheres of the opal template 3- Creating the next layer with different size on the first layer 4- Reinjection of the silica precursor. 5- Repeating the coating layer and injection of the precursor. 6- Finally, selective removal of the opal template by calcination or etching with an organic solvent to create the porous structure of the multisize layered Silica inverse opal photonic crystals. The silica precursor contains a mixture of ethanol, TEOS tetraethyl orthosilicate, and hydrochloric acid.

The results show that the fabricated inverse opals are organized, crack-free, and uniform. It is possible to make the desired number of layers by changing the concentration of the PMMA microspheres' colloidal suspension. By changing the characteristics of photonic crystals, such as their constituent materials and refractive indices, lattice constants, and the number of layers, it is possible to control their photonic properties which are beneficial for different applications.
(Invited) Ir Strangelove: Or How I Learned to Stop Worrying and Embrace the PEM
Authors: Mittelsteadt Cortney
Published: July 2022

There are extremely ambitious plans for rapid growth in hydrogen generation from renewables. PEM (polymer electrolyte membrane) electrolysis is particularly well suited to work with these intrinsically intermittent power sources due to their ability to duty cycle on the seconds timescale. An oft-sited liability of PEM is their reliance on precious group metal, PGM materials, specifically the use of Iridium for the oxygen evolution reaction (OER). Iridium is the rarest natural element on earth, with global production a scant 10 tons/year[1]. Speculation on increased demand has led to a recent price surge as well (Figure 1). Current Ir usage is estimated around 400 g Ir/MW of electrolysis[2]. This would put a cap of 25 GW/year of PEM electrolysis, assuming 100% of production was steered towards electrolysis, away from current uses, which include crucibles, chlor-alkali catalyst and spark plugs.

These perceived challenges have motivated a healthy increase in alkaline exchange membrane (AEM) electrolysis, which can operate without the use of PGMs. AEMs have yet to demonstrate suitable durability, and have other system implications. The iridium availability cap can be greatly increased, however, by lowering Ir loadings on an areal basis and increasing current density. Furthermore, platinum which is far more prevalent can be used as a substitute, however at the cost of efficiency. This talk will look at how much iridium is needed, the likelihood of increased production, the cost iridium in PEM electrolysis, the use of substitutes, either membrane or catalyst systems to determine if the total addressable market for hydrogen electrolysis can be met by PEM.

[1] M. Garside Statista, https://www.statista.com/statistics/585840/demand-for-iridium-worldwide/

[2] Ahmad Mayyas, Mark Ruth, Bryan Pivovar, Guido Bender, and Keith Wipke,
Manufacturing Cost Analysis for Proton Exchange Membrane Water Electrolyzers
. NREL, Aug, 2019. https://www.nrel.gov/docs/fy19osti/72740.pdf

Figure 1
(Invited) AEM Electrolyzers for Green Hydrogen: Current Status and Future Challenges
Authors: Yan Yushan
Published: July 2022

Green hydrogen from wind and solar electricity is necessary to decarbonize certain sectors of our economy that are inaccessible by renewable electricity, and it has the potential to reduce more than 30% of the global carbon emission. For low temperature membraned electrolyzers, polymer electrolytes play a critical role in controlling their cost, performance, and durability, and consequently their economic viability. In this presentation, I will focus on our work on anion exchange membrane electrolyzers. More specifically I will highlight the progress we have made in developing one of the most stable membranes and the corresponding electrolyzers. Current status and future challenges will be presented.
Alteration of Oxygen Evolution Mechanisms in Layered LiCoO2 Structures By Intercalation of Alkali Metal Ions
Authors: Kim Yohan , Kim Seongmin , Shim Minyoung , Oh Yusik , Lee Kug-Seung , Jung Yousung , Byon Hye Ryung
Published: July 2022

The word ‘Sustainability’, including carbon neutrality, has dominated the direction of social development over the past decade. In particular, energy conversion reactions through electrochemical methods are one of the efficient methods of obtaining small carbon footprint fuels. The oxygen evolution reaction (OER) is a key step in determining the overall reaction efficiency of fuel-related electrochemical reactions such as CO2 reduction reaction and H2 evolution reaction. However, electron transfer is sluggish for OER due to 4 electrons per one O2 molecule. This promotes multiple studies on the metal oxide electrocatalyst structure.

The Alkali-transition metal oxides with the layered structure are one of the attractive OER electrocatalyst series. For example, lithium cobalt oxide (LiCoO2, LCO) presented OER activity through Li+ extraction (delithiation) from the lattice structure. In this work, we investigated the insertion effect of large alkaline cations (A+: Na+, K+, and Cs+) at the delithiated LCO for OER activity and stability.

The intercalations of hydrated Na+ and K+ induced significant phase transformation of the delithiated LCO structure. In addition, the relative ratio between Co and alkali metal species determined the average Co oxidation state of LCO. We found that OER activity was improved in the order of Li+ < Na+ < K+, which was associated with the increased Co valence state and the Co-O bond covalency. Consistently, density functional theory (DFT) simulation also predicted the formation of efficient OER active sites by the K+ insertion. In comparison, Cs+ insertion exhibited the highest OER activity and demonstrated different OER processes. Due to the larger Cs+ size, the cation insertion was predominantly achieved at the delithiated LCO surface, resulting in imposing tensile strain to the surface edge. This catalyst showed the significant pH dependency on the OER property, suggesting the lattice-oxygen-based pathway for LCO. However, the bulk structure was preserved with little phase transformation, demonstrating better OER stability than others. In the presentation, I will discuss the catalytic activity responsible for the cation sizes and two different mechanisms in detail.

Figure 1
Multi-Walled Carbon Nanotube Supported Manganese Selenide As Highly Active Bifunctional OER and ORR Electrocatalyst
Authors: Singh Harish , Hines McKenzie Marley , Chakravarty Shatadru , Nath Manashi
Published: July 2022

Transition metal selenides have attracted intensive interest as cost-effective electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) because of the continuous thrust in sustainable energy conversion. In this article a Mn-based bifunctional electrocatalyst, MnSe has been identified which shows efficient OER and ORR activity in alkaline medium. The catalytic activity could be further enhanced by using multiwalled carbon nanotubes (MWCNT) asadditives which increases the charge transfer and electronic conductivity of the catalyst composite. This MnSe@MWCNT catalyst composite exhibits a very low overpotential of 210 mV at 50 mA cm-2 when deposited on Ni foam, which outperforms state-of-the-art RuO2 as well as other oxide and Mn-based electrocatalysts. Furthermore, the composite’s facile OER kinetics was evidenced by its small Tafel slope of 54.76 mV dec–1 and low charge transfer resistance, indicating quick transport of the reactant species. The MnSe@MWCNT also exhibited efficient electrocatalytic activity for ORR with a Eonset of 0.94 V, which is among the best reported till date for chalcogenide based ORR electrocatalysts. More importantly, this MnSe-based ORR electrocatalyst exhibits high degree of methanol tolerance, showing no degradation of catalyst performance in presence of copious quantities of methanol, thereby out-performing state-of-the-art Pt electrocatalyst. The catalyst compositie also exhibited exceptional functional and compositional stability for OER and ORR after prolonged period of continuous operation in alkaline medium. The surface Raman analysis after OER revealed the retention of manganese selenide surface with evidence of Mn-oxo coordination confirming the formation of mixed anionic (oxy)selenide as the active surface for OER. Such efficient bifunctional OER and ORR activity makes this MnSe based catalyst attractive for overall electrolysis in regenerative as well as direct methanol fuel cells.
Dopant-Free Conductive SnO2/CNT Support for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolysis
Authors: Kim Eom-Ji , Bak Junu , Shin Dongwon , Song DongHoon , Cho EunAe
Published: July 2022

Polymer electrolyte membrane water electrolysis (PEMWE) is an energy conversion device for producing green hydrogen, which is one of the key elements for moving toward a hydrogen society. However, there are two obstacles to the commercialization of PEMWE, which are cost and durability. In particular, a large amount of a noble metal catalyst such as ruthenium (Ru) or iridium (Ir) is required for the oxygen evolution reaction (OER) occurring at the anode electrode. To reduce the usage of noble metal catalysts, carbon supports could be introduced. However, due to the harsh conditions resulting from the high voltage and acidic environment in the anode, the carbon easily corrodes and decomposes into carbon dioxide. To prevent corrosion of support materials, metal oxide support can be used. Tin oxide (SnO2) is one of good candidate support because it is stable under acidic and high potential conditions. However, the electrical conductivity of SnO2 needs to be increased to be used as an anode support material for PEMWE. In previous studies, the electrical conductivity of SnO2 was increased by the introduction of dopants such as antimony (Sb), indium (In), fluorine (F) and so on. However, recently, it was reported that these dopants can be dissolved under the OER conditions. Thus, a new approach for synthesizing dopant-free and stable metal oxide supports is required.

Herein, we report tin oxide-carbon nanotube composite (SnO2-CNT) support for the anode in PEMWE. The SnO2 nanoparticles were coated on CNT for high conductivity and stability. For evaluating the electrochemical performance, Ir nanoparticles were supported on SnO2-CNT. Ir/SnO2-CNT showed high OER activity and stability under acidic conditions. These results demonstrated that SnO2-CNT support can be utilized for reducing the amount of precious metal catalysts and increasing the stability of OER supported catalyst in PEMWE.
Gel Polymer Electrolytes for Zinc-Air Batteries Operating at Low Temperatures
Authors: Cui Jiayao , Chung Hyun-Joong , Ivey Douglas G
Published: July 2022

Zinc-air batteries (ZABs) have gained much attention from researchers in recent years, partly due to their high theoretical energy density as well as improved safety and the abundance of zinc relative to lithium in lithium-ion batteries (LIBs). Gel polymer electrolytes (GPEs) in ZABs can act as a separator and, therefore, can reduce the effect of dendrite formation at the zinc electrode. The temperature of many areas in Canada can be extremely low (less than -30oC) in the winter and many batteries do not work well at such low temperatures, mainly due to reduced rates for the electrochemical reactions in the battery. The objective of this work is to develop a GPE for ZABs using in-situ fabrication. The use of in-situ gelation can reduce the contact resistance between the GPE and the electrodes, thereby improving ion transport between the electrolyte and electrodes. The GPEs in this work are fabricated using poly(acrylic acid), crosslinked with KOH and a final immersion step in a mixture of additives. The additives are utilized to improve the performance of ZABs at low temperatures. As a redox mediator, KI can change the traditional oxygen evolution reaction in ZABs to a more thermodynamically favored reaction. ZnO is used to improve the cyclability of ZABs, whereas ethylene glycol is used to reduce the effect of hydrogel evolution at the zinc electrode.