bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Nanoscale Devices for Accelerating AI Algorithms
Authors: Kapadia Rehan , Ahsan Ragib , Chae Hyun Uk , Tao Jun 
Published: February 2024

The energy consumption of training and deploying state-of-the-art artificial intelligence (AI) models has experienced exponential growth, driven by increasing model parameters and the necessary training data. Recent models demand over 1 billion PetaFLOPs of total computation for training, potentially taking weeks to complete. With current GPU performance at approximately 1-3 TOPS/W, GPU training energy consumption alone can exceed 100,000 kWh, equivalent to the monthly energy expenditure of 100 US households. Over the next decade, these models are expected to scale up further, driving total computing energy to constitute a significant portion of global consumption. In this talk, we describe both synaptic and neuronal devices that can accelerate AI algorithms with potentially multiple orders of magnitude improvement in power efficiency.
First, we describe an oscillatory retinal neuron (ORN) that directly converts incident DC light into voltage spikes. Coupled arrays of this device result in an imager that carries out in-sensor processing while capturing an image. Uniquely, the conversion from input light to output voltage spikes occurs without external power. When coupled in arrays, the neighboring neurons interact with each other to influence the spiking frequency spectrum. This allows the arrays to carry out frequency multiplexed computation on an input image. It is shown that this approach can achieve>20,000 TOPS/W, multiple orders of magnitude greater than the current approaches. Theory and simulation is used to elucidate how coupled ORNs carry out computation on an input image. When coupled, each output frequency band encodes a unique computation on the input image. By tuning the coupling impedances and the frequency bands, user defined computations can be carried out on the input. We experimentally show that this can be carried out with a 3x3 array that demonstrates simultaneous edge detection, intensity filtering, image segmentation and other functions. This hardware is then used to demonstrate improvement in MNIST handwritten digit classification accuracy over a traditional imager connected to a fully connected network.
Next, we describe spiking synaptic devices that can be directly fabricated in the back-end of line of CMOS devices. These devices consist of an InP transistor channel with an engineered gate stack. Using a uniform gate insulator, we can demonstrate behaviors of biological synapses, such as potentiation, depression, spike number dependent plasticity, and spike timing dependent plasticity. By introducing a heterostructured gate insulator, it is shown that short-term to long-term memory transitions can be designed into the device. Finally, by using a transparent gate, an in-sensor synaptic phototransistor is demonstrated and the performance of these devices at a system level is demonstrated.
(Invited) Safety of Li-Ion Batteries: Current Challenges in a Policy Context
Authors: Pfrang Andreas , Adanouj Ibtissam , Bruchhausen Matthias , Da Costa Barata Ricardo , Hildebrand Stephan , Lazareanu Mircea , Leite Patrão Rafael , Lebedeva Natalia 
Published: February 2024

Batteries are a key technology required to meet our objective for climate neutrality, to reduce dependency on fuel imports as well as to ensure maximum use of renewable electricity. Over 80 GW / 160 GWh of stationary batteries and over 50 million electric vehicles are expected in the EU by 2030. Lithium-ion batteries are expected to dominate the market well beyond 2030, while developments in other technologies will continue in parallel. Battery-related policies are currently of high interest and have to evolve quickly in order to facilitate and accommodate technological progress.
With increasing numbers of electric vehicles and batteries in operation and the parallel rise of energy density in lithium-ion batteries, risks related to battery safety e.g., through battery fires, increase. The Joint Research Centre (JRC) carries out research on battery safety to support policymaking and develop fit-for-purpose testing methodologies: the recently proposed Batteries Regulation, aiming at a sustainable battery value chain, foresees new safety requirements for stationary batteries. Another example is the Global Technical Regulation on Electric Vehicle Safety, where a thermal propagation test procedure is being developed with international partners.
In this context, thermal runaway initiation methods and criteria for thermal runaway events had been analysed. A rapid heating method and suitable criteria for thermal runaway were applied in a thermal propagation test campaign on full electric vehicles and corresponding battery packs. While a high degree of reproducibility was observed, a difference in severity between pack and vehicle-level tests was found, and gas emissions from the tests are currently being analysed.

Figure 1
Modeling and Analysis of Coupled Thermal and Mechanical Capacity Degradation in Silicon-Based Lithium-Ion Batteries
Authors: Mishra Lubhani , Subramaniam Akshay , Garrick Taylor R. , Subramanian Venkat R. 
Published: February 2024

Large-format cells are gaining popularity for battery electric vehicles (BEVs) to maximize volumetric and gravimetric energy densities but are associated with challenges in ensuring adequate thermal management. Spatial current density and temperature variations negatively affect overall cell utilization and lifetime.In addition, the mechanical stresses generated within the silicon-based battery electrodes also cause aging and resultant capacity loss. The coupled effects of the thermal and mechanical factors could thus particularly exacerbate cell capacity degradation. Rigorous mechano-thermo-electrochemical models for battery degradation can be a powerful complementary tool to understand these phenomena better. Simulating performance scenarios can significantly improve cell design and experimentation while reducing time and cost commitments. Model-based design approaches thus have the potential to yield substantial economic benefits.
This work shall serve as an extension to the previously developed thermal degradation model for non-uniform aging in lithium-ion batteries by coupling with mechanical models predicting the effects of volume change within the batteries over cycling. The observed capacity fade trend for a given battery is ultimately the result of an interplay between multiple degradation mechanisms, which depend on a range of design and operating parameters. The errors between the model predictions and experimental data can provide information on the suitability of a given model and the relative prevalence of a given degradation mechanism, with functional and practical benefits, as there exists significant variation in the parameters, mechanisms, and predictive capability of models in the literature. In addition, a rigorous model of volume changes increases the accuracy of predictions of dynamic stress-strain profiles, which in turn helps improve predictions of associated mechanical degradation phenomena. As a first step towards including mechanical effects, the current model builds on the previously reported studies for modeling volume change in porous electrodes due to intercalation (deintercalation) during lithiation (delithiation). This volume change leads to dimensional and porosity changes in the porous electrodes. Furthermore, these mechanical models will help predict generated stresses and strain profiles within the battery and will be related to models of resultant degradation, especially in the case of silicon/graphite electrodes characterized by substantial volume changes.
Swelling of Polypropylene Separators and Its Effect on the Lithium-Ion Battery Performance
Authors: Gor Gennady , Maksimov Andrei V , Maksimova Olga , Molina Marcos 
Published: February 2024

The safety of lithium-ion batteries (LIBs) depends on separators -- porous materials providing ionic transport between the electrodes while preventing them from direct contact. Many commercial separator materials are polymers, e.g., polypropylene. Polypropylene has a non-polar structure, so it tends to interact favorably with non-polar solvents, such as carbonates used in LIBs as electrolyte solvents. These favorable interactions result in two effects: separator plasticization (softening) [1] and swelling [2]. Both swelling and plasticization affect the battery performance and cause safety concerns.
Here we present a model which predicts the swelling of a porous polymer separator based on the molecular structures of the polymer and the solvent. The model is based on Flory's theory of polymer solutions and the Flory–Huggins parameter for polymer–solvent interactions. We introduced two additional parameters to Flory's theory, taking into account the complex structure of the porous polymers. These two parameters can be obtained from experimental data on two solvents. The Flory–Huggins parameter is calculated based on the UNIFAC-FV group contribution method for a given polymer–solvent pair. Our model predicts swelling of polypropylene separators in various solvents, matching the experimental data [3] quite well. By relating the swelling of the separator to the change in its porosity and tortuosity, we estimated the increase of cell impedance as a result of the swelling.
Finally, the plasticization of the separator makes it less persistent to mechanical impacts, increasing the chances of failure. Since the solvent-induced plasticization of the separator is correlated with its swelling [3], our model can also be utilized to assess this effect. Therefore, our model can be used to quickly evaluate various polymer–solvent pairs for application in lithium-ion batteries.
1. Sheidaei, A.; Xiao, X.; Huang, X.; Hitt, J. Mechanical behavior of a battery separator in electrolyte solutions. J. Power Sources 2011, 196, 8728−8734.
2. Cannarella, J.; Liu, X. Y.; Leng, C.; Sinko, P.; Gor, G. Y.; Arnold, C. B. Mechanical properties of a battery separator under compression and tension. J. Electrochem. Soc. 2014, 161, F3117−F3122.
3. Gor, G. Y.; Cannarella, J.; Leng, C. Z.; Vishnyakov, A.; Arnold, C. B. Swelling and softening of lithium-ion battery separators in electrolyte solvents. J. Power Sources 2015, 294, 167−172.
4. Maksimov, A. V.; Molina, M.; Maksimova, O. G.; Gor, G. Y. Prediction of Swelling of Polypropylene Separators and Its Effect on the Lithium-Ion Battery Performance. ACS Appl. Polym. Mater. 2023, 5(3), 2026-2031.
All-Solid-State Battery Safety Investigation in Calorimeter Coupled with Fast X-Ray Radiography
Authors: Charbonnel Juliette , Darmet Natacha , Deilhes Claire , Broche Ludovic , Reytier Magali , Thivel Pierre Xavier , Vincent Remi 
Published: February 2024

All-solid-state battery (ASSB) are expected to be a solution to increase energy density in Li-ion technology. However, high-energy storage capacities make the safety a crucial issue. The main reactions leading to thermal runaway in conventional LiB are anode/electrolyte at 110 °C, electrolyte decomposition at 150 °C and cathode/electrolyte at 300 °C. Therefore, without liquid electrolyte, it can be expected that ASSB are less likely to have a thermal runaway.
To assess safety of such non-fully mature battery technologies, a new methodology is proposed and a closed calorimeter was designed to perform operando experiments in abuse conditions with high-speed synchrotron X-ray radiography and measurement of temperature, pressure and energy. The data and image of thermal runaway of all-solid-state batteries are presented and compared to the result of Li-ion batteries with liquid electrolyte. An 11 % decrease of heat release was measured for cell with solid electrolyte. Gas volume, amount of matter that reacts in the cell and reaction kinetics have also been compared.
Such a methodology allows deepening hypotheses on associated material degradation and that can assist in development of new battery technologies, by evaluating battery safety from the start of the design from battery composition to cell shape.
Linking Microstructure Modeling of Lithium-Ion Batteries during Rapid Charging to System Performance
Authors: Teel Hunter , Lopata Joseph Steven , Garrick Taylor R. , Wang Fengkun , Zhang Han , Zeng Yangbing , Shimpalee Sirivatch 
Published: February 2024

Battery models can be used to predict conditions ripe for lithium metal plating in the anode during rapid charging. One common procedure is to simulate a rapid charge using a pseudo-two-dimensional (P2D) model and determine if and when the minimum local potential reaches 0.0 V with respect to metallic lithium in the anode. This normally occurs at higher states of charge during a DC fast charging or rapid regenerative charging event. However, we have recently determined that three-dimensional (3D) models, while broadly agreeing with P2D results, demonstrate much variation in the in-plane and through plane direction, which P2D models cannot resolve. Because P2D models employ effective medium approximations, any “local” value in the P2D space along the through-plane coordinate represents an average across a slice of the domain. Therefore, it may be insufficient to use minimum anode potentials from P2D models as indicators of local plating and may only be representative of global lithium plating onset.
The results of rapid-charge 3D microstructure simulations are compared to P2D results [1,2]. This allows us to verify whether rapid charging induces negative local potentials at the anode active material surface that are left undetected in a P2D model. The expected result implies that the 3D microstructure model is necessary to predict the onset of lithium plating. We then extend our previous study to look at the impact of design changes on the microstructure performance, and then link the microstructure performance changes to performance metrics at the battery cell, module, pack, and vehicle level.
References

J. S. Lopata, T. R. Garrick, F. Wang, H. Zhang, Y. Zeng and S. Shimpalee, ECSarXiv (2022).

J. S. Lopata, T. R. Garrick, F. Wang, H. Zhang, Y. Zeng and S. Shimpalee, J Electrochem Soc, 170, 020530 (2023).
Comprehensive Analysis of Performance Evolution and Failure Mechanisms for Commercial Large-Format NMC-Gr Lithium-Ion Pouch Cells
Authors: Gasper Paul , Thakkar Foram , Sunderlin Nathaniel , Saxon Aron , Schiek Andrew , Finegan Donal P. , Smith Kandler 
Published: February 2024

With the accelerating adoption of lithium-ion battery systems, careful analysis of the performance evolution and failure mechanisms of commercially produced batteries is crucial for predicting the lifetime of battery systems, estimating operating and maintenance costs, and ensuring safe operation. Here, we present the results of a 2-year aging study conducted on large-format NMC-Gr pouch cells from a large battery manufacturer. Calendar and cycle aging tests were conducted on 23 cells, with calendar aging conducted at varying temperature and state-of-charge, and cycle aging conducted at varying temperatures, average voltage, voltage window, charge-discharge rates, using both constant-current cycling and drive cycles.
The evolution of cell performance throughout aging was observed using electrochemical characterization tests. DC pulses show a general trend of decreasing then increasing resistance, while EIS measurements are used to deconvolute resistance evolution modes. Capacity checks show decreasing capacity throughout life for all cells. Fitting of C/20 charge and discharge curves using half-cell voltage data is used to quantify loss of lithium inventory and loss of active material degradation modes, as well as reveal the de/lithiation window experienced by electrodes throughout aging.
While cell performance evolution is often neatly explained by a few key degradation modes, cell failures observed during testing were often the result of several interacting degradation mechanisms. Degradation mechanisms were identified by a variety of physical, electrochemical, and microstructural characterizations. Key degradation mechanisms observed were SEI growth at graphite/electrolyte interfaces, electrolyte decomposition and gassing leading, NMC particle cracking, Li plating, and electrode dry-out. Degradation mechanisms observable in early life often initiate new failure mechanism that lead to cell failure or safety concerns through physical or electrochemical interactions. The findings demonstrate the multi-faceted challenge of cell lifetime and failure prediction in real-world systems.
(Invited) Challenges in Fabricating and Scaling up Silicon Carbide Wafers and Devices
Authors: Das Hrishikesh , Kostelnik Petr , Kocian Karel , Novak Tomas , Domeij Martin , Sunkari Swapna , Justice Joshua 
Published: February 2024

Silicon Carbide is rapidly growing in the power electronics industry. This is fueled to a great degree by the adoption of electric cars and power electronics needed both inside the vehicle and to support the charging infrastructure. This attention from automotive industry comes with a clear spotlight on the cost, quality, and efficiency of SiC power devices. This in turn results in intense pressure and scrutiny to improve yields and reduce defects in every part of the manufacturing chain. There is a wide release and proliferation of Diode and MOSFET devices from various companies in the marketplace. Several companies are investing billions of dollars in capacity expansions driving exponential growth of wafers and devices.
In this review, we will discuss the steps and processes of fabricating a SiC wafer including crystal growth, wafering, epitaxy and device fabrication. The process challenges associated with the steps unique to SiC will be highlighted with a perspective on scaling up volumes and the transition to 200mm wafers. New innovations at some of the steps are enabling higher efficiency and output. The impact of these innovations will be presented. In addition, defects at each step of the process will be reviewed along with how they interact with the following steps [1]. Finally, the effect of various processes and defects on devices and reliability will be presented [2,3].
References:

H. Das, et. al., Mater. Sci. Forum, Vol. 1004, pp 458-463, (2020)

T. Neyer et. al., 2021 IEEE International Reliability Physics Symposium (IRPS), pp. 1-6, (2021)

S. Kochoska et. al., Mater. Sci. Forum, Vol. 1062, pp 554-559, (2022)
(Invited) Effect of Seed Crystal Orientation on Ammonothermal Growth of GaN
Authors: Valenzuela Jonny , Pimputkar Siddha 
Published: February 2024

Gallium nitride (GaN) is a wide bandgap semiconductor which has received widespread attention as it has enabled the development of short wavelength (UV, blue) optical emitters and promises a new generation of high efficiency power electronic devices. To enable widespread use of high power, high efficiency devices, the availability of large-area, inexpensive, low-defect-density GaN substrates is necessary.
The ammonothermal method is a bulk, single crystal growth method which has demonstrated growth of high structural quality GaN boules greater than 2 inches in diameter. Despite these demonstrations, challenges remain with regards to improving growth rates to reduce cost of boules and understanding the growth behavior of GaN in these environments to further improve upon crystal quality. In particular, the general trend and affect of the GaN seed crystal on growth rates and crystal quality has not been studied in detail.
This talk will discuss our current understanding of how the initial seed crystal orientation affects the resulting ammonothermal GaN growth, surface morphology, crystal quality, and impurity incorporation. Seed crystals were sourced from hydride vapor phase epitaxial (HVPE) grown GaN boules that were sliced and polished to atomically smooth crystallographic facets of varying orientations. Three series were created resulting in incrementally changing orientations ranging from +c-plane to m-plane to -c-plane, from +c-plane to a-plane to -c-plane and from m-plane to a-plane.
(Invited) Application of 3D in-Situ X-Ray Visualization to Track the Formation of Dislocation Clusters during PVT Growth of SiC
Authors: Wellmann Peter , Strüber Sven , Steiner Johannes , Ihle Jonas , Schultheiss Jana , Nguyen Binh Duong , Sandfeld Stefan , Salamon Michael , Uhlmann Norman 
Published: February 2024

SiC has become the key player among wide bandgap semiconductors for power electronic applications. Since the first description of the physical vapour transport (PVT) growth process of SiC by Tairov and Tsvetkov (J. Crystal Growth, 43, 209(1978)), there has been steady progress in SiC-based crystal growth, epitaxy and device processing. The success of SiC compared to Si is related to its superior material properties such as extremely high electrical breakdown field and high thermal conductivity compared to the standard silicon counterpart. In addition, SiC device processing utilises much of the standard Si processing equipment. A major reason for the success of SiC in power electronic applications compared to other wide bandgap counterparts such as GaN, Ga2O3 and diamond is related to the availability of large diameter SiC wafer materials (150mm = standard, 200mm = developped). Bulk SiC growth is now a very well developed process with comparatively high yields. The extraordinary physical properties also include obstacles related to the strong chemical bonding and complex phase diagram of the material, which pose challenges to the growth process. Therefore, there are still a number of open questions related to the nucleation, progression and termination of the bulk growth process that require fundamental research in materials science and technology.
The aim of this presentation is (i) to give an overview of the state-of-the-art PVT growth process and (ii) to discuss a current research topic dealing with the early stage of the growth process and the defect formation that can occur during the initial nucleation of SiC. We have applied 3D in-situ visualisation of the growth process using X-ray computed tomography to visualise island formation on the large seeding area. These data are related to growth process instabilities such as temperature variations during the seeding process and axial doping level changes from the seed to the newly grown crystal. Both process instabilities induce mechanical stress on the SiC lattice and act as sources for dislocation generation and multiplication. We will show a series of growth processes with varying growth parameters that shed light on the initial growth stage of SiC.
As the crystal diameter of SiC increases from 150 mm to 200 mm, the results of this study become increasingly important.