Nickel-rich lithium-ion batteries (LIBs) with LiNi₀.₈Mn₀.₁Co₀.₁O₂ (NMC811) cathodes are central to global electrification, yet thermal runaway (TR) generates chemically complex and poorly characterized particulate emissions with potential carcinogenicity. This study quantifies size-resolved particulate emissions from 18650 NMC811 cells subjected to 50 kW/m² radiant heating under normoxic conditions, comparing states of charge (SOC) from 0% to 70%. Increasing SOC from 0% to 70% intensified TR, raising peak temperature from 680 to 806 °C and mass loss by 156% (7.59-19.47 g). Total particle number concentration (PNC) decreased by 69% (3.17 × 10⁸ to 9.88 × 10⁷ particles/cm³), yet ultrafine particles (UFPs≤0.1 µm) dominated at both conditions, decreasing from 94% at 0% SOC to 87% at 70% SOC. Conversely, the total PM mass increased by 50% (0.78-1.17 mg), while UFP PM mass decreased by 25%, and the fine (+66%) and coarse (+233%) fractions increased. Metal concentrations surged 531% (1.14-7.20 µg/m³), driven primarily by Ni and Co released from cathode lattice collapse. UFPs-bound high-molecular-weight PAHs increased 451% (945-5205 µgPAH/gPM), reflecting high-temperature polymer pyrolysis and radical-driven aromatic ring growth. Morphology progressed from discrete spheres to metal-decorated fractal agglomerates containing up to 8.24 wt% nickel, capable of penetrating the layers of a firefighter's personal protective jacket. These findings establish SOC as a pivotal modulator of toxicologically synergistic ultrafine metal-PAH hybrids during battery TR, underscoring the need for SOC-informed exposure guidelines, enhanced respiratory protection, and regulatory prioritization of these particles in occupational and environmental risk frameworks.

Lithium-ion batteries have been shown to exhibit accelerated degradation under thermal gradients, even though there remains no clear understanding of the altered underlying transport processes. In this work, we investigate how the temperature difference between anode and cathode, also known as interelectrode thermal gradients, influences the performance of single-layer NMC/graphite pouch cells compared to isothermal conditions. Using voltage profiles and electrochemical impedance spectroscopy, we show that relative to isothermal conditions, thermal gradients increase the total resistance of the cell at all states of charge by increasing the concentration polarization resistance. Moreover, we show that thermal gradients induce entropic and other residual effects in the cell. Galvanostatic intermittent titration technique (GITT) was used to quantify the observed reduction in the apparent diffusion coefficient under thermal gradient conditions. Using a Fickian transport framework, we show that the reduced diffusion necessitates a larger concentration gradient to sustain a constant current, providing a direct physical link to the increased concentration polarization resistance. Overall, this demonstrates how thermal gradients compromise cell performance and establish transport-limited conditions that are consistent with previously reported accelerated degradation observed in Li-ion cells subjected to thermal gradient conditions.

Lithium plating is a critical degradation mechanism in lithium-ion batteries (LIBs) during low-temperature charging, where reduced ionic mobility and slower intercalation kinetics promote metallic lithium deposition on the graphite anode. However, plating behavior in large-format cells such as the commercial 4680 (46 mm diameter, 80 mm height) remains under-characterized. In this work, we investigate lithium plating in 4680 24 Ah cylindrical cells at sub-zero temperatures of −20 °C, −10 °C, and 0 °C, using 22 °C as a baseline. During testing, surface temperatures were monitored using FLIR infrared camera and a thermocouple attached to the battery surface. Cells were charged from 2.7 V to 4.2 V under a constant-current, constant-voltage (CCCV) protocol at C-rates of 0.05C, 0.5C, and 1C, with electrochemical impedance spectroscopy (EIS) performed at designated voltages (state of charge, SOC). EIS results show clear signatures of lithium plating emerging at low temperatures and high charging rates. As temperature decreases from 0 °C to −20 °C, the mid-frequency impedance (1–10 Hz range) exhibits pronounced features indicative of Li plating, with the magnitude of these features increasing at both mid-SOC and 100% SOC conditions. Raising the charge rate to 1C further intensifies the plating-related impedance response and shifts it toward the upper end of the frequency range, reflecting a greater tendency for Li metal deposition during fast charging in cold conditions. Distribution of relaxation times (DRT) analysis of the EIS spectra isolates a distinct peak associated with plating kinetics, separating it from overlapping processes and confirming the presence of a plating process under these conditions. To correlate the impedance signatures with internal cell conditions, a three-dimensional electro-thermal model of the 4680 cell was developed in COMSOL Multiphysics [1]. The model simulates coupled heat generation and electrochemical behavior during charge-discharge, revealing substantial internal temperature gradients and anode overpotentials at sub-zero ambient temperatures. Specifically, at −20 °C and high current, the anode potential drops to levels that thermodynamically favor Li metal deposition. These modeling insights align with the EIS/DRT observations, linking the appearance of mid-frequency plating features to the actual onset of lithium plating within the cell. Overall, the combination of experimental diagnostics, DRT analysis, and physics-based electro-thermal modeling provides a comprehensive understanding of lithium plating in 4680 cells at low temperatures and offers guidance for safer charging strategies in cold-climate electric vehicle operation. Acknowledgment Authors gratefully acknowledge financial support from the Department of War (DoW) Office of Naval Research (ONR) and Air Force Office of Scientific Research through the Defense Established Program to Stimulate Competitive Research (DEPSCoR) under award number FA9550-24-1-0164. References [1] B. R. Das Goswami, Y. Abdisobbouhi, H. Du, F. Mashayek, T. A. Kingston, and V. Yurkiv, “Advancing battery safety: Integrating multiphysics and machine learning for thermal runaway prediction in lithium-ion battery module,” J Power Sources , vol. 614, Sep. 2024, doi: 10.1016/j.jpowsour.2024.235015.

Today, there remains a limited understanding regarding how the use-case conditions of a battery in the first life can affect viability for regeneration to enable equivalent use-case outcomes in a second life. Here, we conducted a systematic study using over 60 regenerated lithium iron phosphate (LFP) cells to evaluate second-life performance with varying first- and second-life cycle stress parameters. Our findings demonstrate that cells subjected to more stressful first-life cycling protocols, such as higher C-rates and depth of discharge, displayed improved second-life cycle-life performance compared to those cycled under milder first-life conditions. This is related to the interplay of degradation mechanisms between loss of active material versus loss of lithium inventory, which dictates the initial state and internal resistance of the cell at the start of its second life. Further, we employ a shallow neural network model for state-of-health (SOH) prediction to a heterogeneous starting population of regenerated second-life cells and demonstrate the use of voltage inputs to enable accurate and reliable SOH analysis. This study demonstrates how the diversity of practical first-life use cases of Li-ion batteries is a key factor in designing effective pathways for high-performing second-life cells.

Growing concerns about public health and national security necessitate the development of compact, integrated systems capable of continuous, real-time collection and detection of biothreats (e.g., viruses and bacteria). In this work, we report an inertial microfluidic-based aerosol capture device for the real-time collection and analysis of airborne particles (e.g., biothreats), motivated by the need for rapid detection capabilities. A two-stage spiral microchannel is designed, fabricated, and evaluated for capturing aerosolized particles with diameters ranging from 0.20 to 1.60 mu m, and its performance is compared to a traditional U-shaped microchannel. The spiral microchannel design is developed with the aid of multiphase computational fluid dynamics (CFD) simulations and tested experimentally to investigate the flow dynamics and particle capture efficiencies. Overall, the experimentally measured particle capture efficiencies agreed well with the simulation results and the two-stage spiral microchannel resulted in significant improvement over the traditional U-shaped microchannel. Both the simulations and experiments on the spiral microchannel design demonstrated approximately a two-fold increase in diversion efficiency and a five-fold increase in entrapment efficiency, on average, while having less than a two-fold increase in pressure drop. The performance improvement in the two-stage spiral microchannel design suggests a promising avenue for the development of next-generation devices capable of providing real-time collection and enrichment of aerosolized biothreats.

In contrast to the extreme cycling conditions required for accelerated aging studies, most commercial 18650s experience mild cycling over their lifetime. To understand how cells’ operational thermal stability changes after mild C-rate cycling, thermal, crystallographic, and electrochemical characterization approaches were combined and applied to LiNi x Co y Al z O 2 /Graphite+Si 18650s that were cycled at C/3 until 70% remaining useful life (>1000 cycles). Contrary to the idea that lower capacity cells generate less heat, the aged cells showed an increase in both instantaneous heat generation (as confirmed by isothermal calorimetry) and temperature (as confirmed by adiabatic calorimetry) during galvanostatic operation. Heat generation was accurately modeled using a two-component reconstruction of reversible heating and joule heating components, measured from entropic potential testing, akin to a temperature-modulated galvanostatic intermittent titration technique experiment. At the same time, entropic potential testing enabled the deconvolution of thermodynamic and kinetic components of heat. Changes in the thermodynamic component (reversible heat generation) directly correlated with crystallographic heterogeneity, as tracked via synchrotron-based in-situ x-ray diffraction (XRD) mapping, suggesting diminished redox activity and a loss of lithium inventory. Changes in the kinetic component (Joule heating) correlated to increased overpotential and internal resistance and jelly roll collapse. This study places the two-component reconstruction and entropic potential testing in conversation with structural (XRD) and electrochemical (dQ/dV) approaches as a key degradation detection technique for the separation of thermodynamic and kinetic factors. This research was performed on APS beam time award from the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

The growing use of lithium-ion batteries (LIBs) in critical applications such as electric vehicles and grid energy storage has escalated concerns regarding their safety, particularly thermal runaway (TR) incidents. This review systematically examines the existing mechanical, electrical, thermal, and chemical abuse testing methodologies for LIBs, highlighting significant variability and inconsistencies across international testing protocols. Through comparative analysis of industry and regulatory standards, the paper identifies inconsistencies and key gaps such as varying heating rates, ambiguous criteria for TR initiation, and inadequate chemical abuse tests. Conversely, successful standardized approaches such as the EUCAR hazard classification and the UL9540 standard illustrate effective methods for reducing risks. Key findings emphasize the urgent need for harmonized international testing protocols incorporating clearly defined metrics across all abuse scenarios (mechanical, thermal, electrical, and chemical) to ensure comparability of results and robust safety margins. For example, mechanical abuse tests should adopt agreed-upon crush and penetration procedures that reflect real-world collision impacts, and electrical abuse tests should use standardized overcharge conditions and cutoff criteria to yield consistent outcomes. The inclusion of chemical exposure tests (such as battery immersion or contamination scenarios) is also advocated, as these are often missing from current standards. Advanced diagnostic tools are discussed as valuable enhancements for early fault detection and risk mitigation. By adopting this framework, stakeholders can significantly enhance the reliability and comparability of LIB safety assessments, thereby mitigating TR risks, fostering innovation, and bolstering consumer confidence in rechargeable batteries.

ABSTRACT This study demonstrates that subjecting Nickel Manganese Cobalt Oxide (NMC) graphite single‐layer pouch cells to temperatures down to −60°C during rest periods leads to performance reduction over 4× greater than control cells tested without low‐temperature exposure. A combination of the observed irreversible electrolyte phase separation effects along with mechanochemical stress build‐up during cathode delithiation results in a combined series of short‐ and long‐term degradation effects associated with low‐temperature exposures. In particular, these findings show that low‐temperature exposures lead to more brittle behavior of primary NMC particles that restrict c ‐axis expansion during delithiation and accelerate localized primary and secondary particle cracking as a long‐term sustained low‐temperature degradation mode. These findings provide mechanistic atomic‐ and molecular‐scale insight into an ongoing and controversial topic of low‐temperature effects in batteries that are central for emerging applications in military, commercial, and space systems.

ABSTRACT Aerosol jet printing presents opportunities for conformal, flexible, and hybrid electronics given its materials compatibility and noncontact nature. However, adoption into production environments remains challenged by complex tradeoffs between throughput, precision, and motion constraints. This is particularly relevant for high‐aspect‐ratio or 3D patterning; however, most literature investigating process optimization regards throughput considerations as secondary to resolution. This work adopts a systematic approach, pushing throughput for aerosol jet printing to identify and address technical challenges associated with ink stability and throughput‐resolution tradeoffs. A heated bubbler is implemented to mitigate ink composition drift within the atomizer, while in‐line heating reduces the effect of throughput on resolution by ∼53%. Operating at high deposition rates pushes the printing process into a liquid wetting regime driven by capillarity, leading to an atypical throughput‐resolution correlation. This knowledge, and associated process advances, enable practical operation of aerosol jet printing for high‐aspect‐ratio structures, demonstrated by printing thermal fins directly onto silicon to realize a ∼69% reduction in thermal resistance under convective cooling. By addressing mechanistic limitations to high‐deposition‐rate aerosol jet printing, this work facilitates a more practical printing process, opening pathways to address complex manufacturing challenges requiring adaptability and precision for high‐value printed electronics.

Thermal variations can evolve within Li-ion batteries as a result of (1) applied cooling, (2) varied thermal conductivity of components, or (3) local defects. We investigated the role of through-plane (current collector to current collector) thermal gradients on li-ion coin cells and single layer pouch cells and observed rapid degradation (within 10 cycles) with a thermal gradient of ~2⁰C. Data analysis and post mortem of the electrode determined that directionality of the through-plane gradient dictated positive electrode or negative electrode dominated degradation modes. We note that within a commercial cell, if a thermal gradient evolves through the layers, alternating thermal gradients will develop due to the use of double-sided electrode coatings on each current collector. We probe the response of 18650 cells undergoing cycling through operando diffraction experiments at the Advanced Photon Source. Extensive cycling of commercial cells under similar cooling environments reveals more rapid degradation than cells subject to less cooling. Further, in efforts to understand the fundamental thermodynamic pheonomena contributing to accelerated degradation, we isolated the response of the electrode and electrolyte components to a thermal gradient using novel electrode entropic potential and solvent entropy measurements. The talk concludes with recommendations to limit thermal gradients and limit performance degradation.

Elucidating the mechanisms of heterogeneous condensation on viral and bacterial envelopes is crucial for understanding biothreat transport phenomena and optimizing capture efficiency in condensation-based detection devices. We investigate the impact of viral envelope geometric parameters [e.g., surface structure pitch-to-diameter ratio (p/d)] due to protruding glycoproteins and surface wettability [via liquid-solid interaction intensity (f)] on heterogeneous condensation using molecular dynamics simulations. Complex glycoprotein structures were modeled as cylindrical pillars to analyze condensation rates and active surface areas across a range of p/d ratios (1.0, 1.2, 1.3, 1.7, 2.0, and ∞) and contact angles (θ = 15°, 75°, and 105°, corresponding to f = 3.0, 2.0, and 1.5) to address envelope geometries for a wide variety of viruses. The results indicate that initial condensation rates on surfaces with intermediate p/d ratios (e.g., 1.2-1.3) are significantly higher due to increased active surface area and droplet cluster formations. The rapid initial condensation fills up the gap between the pillars, reducing the active surface area and leading to a gradual decrease and a plateau in the condensation rate. The increased peak condensation rates are not observed as p/d increased to and above 1.7, as the exhibited behavior is like condensation on the unstructured surface. An increase in surface hydrophilicity (θ = 15°, f = 3.0) leads to faster nucleation and higher peak condensation rates compared to hydrophobic surfaces (θ = 105°, f = 1.5). The influence of viral envelope geometries and surface wettability on the heterogeneous condensation mechanisms offers foundational insights required to understand airborne biothreat transmission, which is particularly important in the atmosphere and respiratory tract, and improve biothreat detection methods utilizing condensation-based capture devices.

Understanding the interplay between electrochemical and thermomechanical phenomena in lithium-ion batteries (LIBs) is critical because of its influence on battery performance and safety. In particular, adverse environmental conditions can lead to accelerated degradation and even catastrophic and unexpected thermal runaway [1]. While commercial cylindrical batteries are well-suited for space applications, their behavior under associated freeze-thaw conditions has yet to be thoroughly investigated. Cathode particle cracking and electrode deformation have been previously identified in LIBs subjected to low temperatures [2]. In this work, we investigate the effect of freeze-thaw cycling on commercial cylindrical cells at various states of charge (SOC). A custom liquid nitrogen-based testing setup is used to subject the batteries to controlled-rate freeze-thaw cycles while under vacuum. Electrochemical cycling and analysis and X-ray computed tomography are performed at room temperature. The effects of SOC and freeze-thaw cycles on electrochemical and thermomechanical phenomena are identified and presented. Gaining insight into these effects is essential to developing LIBs capable of withstanding harsh environments, such as extreme cold. Acknowledgments The authors gratefully acknowledge the NASA Established Program to Stimulate Competitive Research (EPSCoR) Program for funding this research (NASA Grant Number 80NSSC23M0068). The authors also acknowledge Dr. William West and Dr. Marshall Smart (NASA Jet Propulsion Laboratory) for technical discussion of this work and Dr. Sara Nelson, Ms. Hailey Waller, and Ms. Alesha Roll (Iowa NASA EPSCoR) for administrative services. References [1] B. Ng, P. T. Coman, E. Faegh, X. Peng, S. G. Karakalos, X. Jin, W. E. Mustain, and R. E. White, "Low-temperature lithium plating/corrosion hazard in lithium-ion batteries: Electrode rippling, variable states of charge, and thermal and nonthermal runaway," ACS Appl. Energy Mater. , vol. 3, no. 4, pp. 3653–3664, 2020, doi: 10.1021/acsaem.0c00130. [2] J. Li, S. Li, Y. Zhang, Y. Yang, S. Russi, G. Qian, L. Mu, S.-J. Lee, Z. Yang, J.-S. Lee, P. Pianetta, J. Qiu, D. Ratner, P. Cloetens, K. Zhao, F. Lin, and Y. Liu, "Multiphase, multiscale chemomechanics at extreme low temperatures: Battery electrodes for operation in a wide temperature range," Adv. Energy Mater. , vol. 11, no. 37, p. 2102122, 2021, doi: 10.1002/aenm.202102122.

Non-uniform temperature distributions within lithium-ion cells caused by internal heat generation and external cooling can create thermal gradients that adversely affect performance and safety [1-3]. The direction of these gradients impacts local transport mechanisms, leading to varied degradation modes. Previous studies have shown that static thermal gradients, which remain constant during charging and discharging, can cause accelerated capacity fade [3-4]. However, thermal gradients are dynamic in practical applications due to fluctuating power demands, heat rejection, and environmental conditions. In this work, we investigate the effects of thermal gradient directions on lithium-ion migration directions using a unique thermal gradient modulation capability. Instrumented three-electrode single-layer pouch cells featuring NMC cathodes and graphite anodes are utilized to investigate each electrode’s overpotential under isothermal and static and dynamic thermal gradient conditions. The direction of the thermal gradient relative to the Li-ion migration direction is shown to significantly impact the cell characteristics. Post-mortem analysis is also used to corroborate the electrochemical behavior. Acknowledgments The authors thank Dr. Michele Anderson (Office of Naval Research, grant N00014-22-1-2411) for financial support of this work References [1] D. Werner, S. Paarmann, A. Wiebelt, and T. Wetzel, “Inhomogeneous temperature distribution affecting the cyclic aging of Li-Ion cells. Part I: Experimental investigation,” Batteries , vol. 6, no. 1, 2020, doi: 10.3390/batteries6010013. [2] C. Fear, M. Parmananda, V. Kabra, R. Carter, C. T. Love, and P. P. Mukherjee, “Mechanistic underpinnings of thermal gradient induced inhomogeneity in lithium plating,” Energy Storage Mater. , vol. 35, no. July 2020, pp. 500–511, 2021, doi: 10.1016/j.ensm.2020.11.029. [3] R. Carter, T.A. Kingston, R.W. Atkinson, M. Parmananda, M. Dubarry, C. Fear, P.P. Mukherjee, and C.T. Love “Directionality of thermal gradients in lithium-ion batteries dictates diverging degradation modes,” Cell Reports Phys. Sci. , vol. 2, no. 3, p. 100351, 2021, doi: 10.1016/j.xcrp.2021.100351. [4] R. Carter and C. T. Love, “Modulation of Lithium Plating in Li-Ion Batteries with External Thermal Gradient,” ACS Appl. Mater. Interfaces , vol. 10, no. 31, pp. 26328–26334, 2018, doi: 10.1021/acsami.8b09131.

Fast charging can induce thermal gradients within batteries, significantly affecting their performance and safety characteristics. Through-plane (interelectrode) thermal gradients can accelerate cell degradation and often lead to lithium plating at the anode [1]. Since electrolyte transport properties, such as ionic conductivity and diffusion coefficient, are dependent on both temperature and salt concentration, their impact under varying thermal conditions warrants investigation [2-4]. These changes in transport properties can result in exacerbated aging in batteries due to hindered ion transport. This study explores the effects of electrolyte salt concentrations on LFP/graphite cell performance under various imposed thermal gradients. LiPF 6 salt dissolved in EC:DEC was used as the electrolyte because of its commercial popularity. . Resistance due to concentration polarization is quantified, revealing elevated resistances under interelectrode thermal gradient conditions across all electrolyte concentrations. Notably, cells with higher electrolyte concentrations exhibit larger concentration polarization resistances under thermal gradients compared to lower electrolyte concentrations. These findings provide insights into the coupled effects of electrolyte concentration and thermal gradients on battery degradation. Acknowledgments The authors thank Dr. Michele Anderson (Office of Naval Research, grant N00014-22-1-2411) for financial support of this work. The authors also acknowledge Dr. Rachel Carter, Dr. Louis Morris, and Dr. Patrick West (U.S. Naval Research Laboratory) for the technical discussion of this work.

Two-phase gas-liquid flows are commonly encountered in various industrial processes. The slug flow regime, characterized by alternating streamwise segments of gas bubbles and liquid slugs, is frequently observed in microscale channels where capillary forces play an important role. Accurate knowledge of the liquid film thickness surrounding bubbles during slug flow is crucial for predicting various hydrodynamic, interfacial, and thermal transport characteristics of interest, such as heat transfer during microchannel flow boiling. In this study, we experimentally and numerically investigate the effect of bubble length and velocity on liquid film thickness in an air-water slug flow in a single microchannel of circular cross-section. In the experiments, an open-loop flow facility is used to generate air-water slug flow in a circular microchannel with independently varying bubble lengths and velocities. A laser confocal displacement meter is used to measure the liquid film thickness, while the bubble length and velocity are extracted from high-speed visualizations. The liquid film thickness is observed to increase with increasing bubble velocity and length; while this effect of velocity has been reported in the literature, this is the first reporting of the influence of bubble length on liquid film thickness. Additionally, numerical simulations that replicate the experimental boundary conditions are performed using a two-phase volume-of-fluid approach to corroborate this trend. Furthermore, as the bubble length increases for a given bubble velocity, the film thickness asymptotically approaches a maximum value that agrees with the semiinfinite bubble approximation previously reported in the literature. A new empirical correlation is developed that is valid for all bubble lengths and offers accurate predictions [9 % mean absolute error (MAE)] of the liquid film thickness as a function of the dimensionless bubble length and dimensionless capillary number.

A comprehensive understanding of the solid-electrolyte interphase (SEI) in lithium-ion batteries is crucial for improving energy efficiency, battery performance, and safety. In this study, a transformer-based instance segmentation framework, integrating deep convolutional neural networks is introduced with a feature pyramid network (FPN), to quantitatively analyze High-Resolution Transmission Electron Microscopy (HRTEM) images and explain the complex microstructural features of the SEI. The model is trained on a dataset of simulated HRTEM images generated using Density Functional Theory (DFT)-optimized grain boundary (GB) structures and calibrated with experimental microscope parameters. The model achieves robust segmentation performance, with training and validation mean intersection over union (mIOU) values of 0.98 and 0.96, respectively. On unseen test data, the model attains mean area match (AM) scores of 91.4% for GBs, 92.3% for Li2CO3, 91.7% for LiF, 88.7% for LiOH, and 88.6% for Li2O. These quantitative results highlight the model's high fidelity and its ability to capture subtle variations in crystallographic orientations and material contrasts. By enabling detailed, statistically grounded segmentation of SEI components, the approach offers valuable insights into ion transport and degradation mechanisms, paving the way for more resilient and efficient energy storage solutions.

Thermal runaway (TR) in commercial lithium-ion batteries (LIBs), is a critical challenge for electric vehicles (EVs) safety. This research presents a comprehensive approach to predicting and mitigating TR by integrating experimental testing, multiphysics modeling, and machine learning (ML). Experimental tests were conducted on high capacity commercial cylindrical batteries (e.g., 24 Ah) under thoroughly controlled temperature and humidity conditions, with surface temperatures monitored via FLIR infrared cameras and thermal sensors. Battery cycling was performed across a range of C-rates, including Federal Test Procedure 75 ( FTP75) driving cycle to emulate realistic usage patterns, with temperatures varying from –20 °C to 40 °C to assess battery performance under both extreme cold and heat. Throughout these tests, electrochemical impedance spectroscopy (EIS) was conducted at various states of discharge to capture dynamic resistance characteristics and to assess degradation over time. Prolonged cycling experiments were also performed to monitor capacity fade and identify early signs of TR through changes in impedance. Accelerated rate calorimetry (ARC) was employed to identify the onset of exothermic reactions and quantify heat generation rates. Overcharge and overdischarge tests were conducted to investigate distinct thermal and electrochemical signatures during abusive conditions. These results were contextualized with thermal and electrochemical data collected during cycling, providing comprehensive insights into the battery's thermal behavior and response under varied operational and stress conditions. Data from these experiments informed a previously developed multiphysics model 1 simulating internal heat generation, solid-electrolyte interphase (SEI) layer dynamics, and the formation of thermal hotspots under diverse operational scenarios. For ML, both surface battery temperature data from thermal camera and sensor readings were utilized, providing a rich dataset to train models on the spatial and temporal aspects of thermal behavior. A transformer-based ML model with attention mechanisms was employed to predict temperature evolution and identify conditions that correlate to early onset of TR. The attention mechanism allowed the model to focus on critical time steps and temperature readings that correlate strongly with TR onset, enhancing its ability to detect TR accurately. This transformer-based approach achieved high accuracy in identifying early warning signs of TR, enabling real-time monitoring and supporting enhanced safety measures in practical battery systems. This integrated methodology represents significant progress in TR prediction for Li-ion cells, aligning with the growing demand for advanced safety solutions in electric vehicles and stationary energy storage applications. Acknowledgment: Authors gratefully acknowledge financial support from the Department of Defense (DoD) Office of Naval Research (ONR) and Air Force Office of Scientific Research through the Defense Established Program to Stimulate Competitive Research (DEPSCoR) under award number FA9550-24-1-0164. References (1) Das Goswami, B. R.; Abdisobbouhi, Y.; Du, H.; Mashayek, F.; Kingston, T. A.; Yurkiv, V. Advancing Battery Safety: Integrating Multiphysics and Machine Learning for Thermal Runaway Prediction in Lithium-Ion Battery Module. J Power Sources 2024 , 614 . https://doi.org/10.1016/j.jpowsour.2024.235015.

Understanding the mechanisms of thermo-electrochemical coupling in lithium-ion batteries (LIBs) is critical due to their safety, reliability, and performance implications [1]. This study examines the effects of electrolyte concentration and thermal gradients on concentration polarization resistance in single-layer instrumented LIB cells featuring nickel manganese cobalt (NMC) oxide cathodes and graphite (Gr) anodes. In this investigation, we vary the concentration of LiPF 6 salt in a 50:50 by-volume mixture of ethylene carbonate and diethyl carbonate to create the electrolytes. By subjecting cells with varying electrolyte concentrations to various thermal gradient conditions during electrochemical cycling, we explore their interplay and its effect on concentration polarization in NMC/Gr batteries. We also utilize electrochemical impedance spectroscopy and pseudo-open circuit voltage to quantify the impact on concentration polarization and the corresponding resistance. These insights aim to advance the understanding of thermal and electrochemical interplay in NMC-based LIBs, providing a pathway for better battery design and performance under various operating conditions. Acknowledgments The authors thank Dr. Michele Anderson (Office of Naval Research, grant N00014-22-1-2411) for the financial support of this work. The authors also acknowledge Dr. Rachel Carter, Dr. Louis Morris, and Dr. Patrick West (U.S. Naval Research Laboratory) for the technical discussion of this work. References [1] S. Ma, M. Jiang, P. Tao, C. Song, J. Wu, J. Wang, T. Deng, W.J.P.i.N.S.M.I. Shang, Temperature effect and thermal impact in lithium-ion batteries: A review, 28 (2018) 653-666.

Li-ion batteries (LIBs) are at the forefront of modern-day sustainable energy storage solutions, with an ever-increasing interest in lithium iron phosphate (LFP) cathodes. With a growing need for energy storage solutions at extreme temperature conditions (e.g., space and electric vehicle applications), which are known to have detrimental effects on battery performance [1–2], mechanistically determining the low-temperature effects on these battery systems is of utmost necessity. Recent studies indicate that storing NMC-based LIBs at low temperatures can lead to electrode degradation and hence, reduced performance under normal temperatures [3]. Moreover, our previous studies reveal that numerous freeze-thaw cycles on NMC-based LIBs typically results in reduced performance due to electrode degradation and other detrimental effects on the electrolyte. However, the effects of low-temperature exposure on LFP-based LIBs are currently not well understood. In this work, we investigate these effects using single-layer LFP/Gr pouch cells. These cells are thermally cycled using controlled heating and cooling rates between 25°C and -60°C. Galvanostatic cycling and electrochemical impedance spectroscopy are performed between the thermal cycles to quantify the electrochemical performance and the effects of the low-temperature exposures. Overall, the cells exhibit increased capacity fade, polarization, and interface resistance, even with a relatively low number of thermal cycles. Post-mortem analysis (e.g., X-ray diffraction and scanning electron microscopy) is then performed to further assess the underlying mechanisms. Acknowledgments The authors gratefully acknowledge the NASA Established Program to Stimulate Competitive Research (EPSCoR) Program for funding this research (NASA Grant Number 80NSSC23M0068). The authors also acknowledge Dr. William West and Dr. Marshall Smart (NASA Jet Propulsion Laboratory) for technical discussion of this work and Dr. Sara Nelson, Ms. Hailey Waller, and Ms. Alesha Roll (Iowa NASA EPSCoR) for administrative services. References [1] Li Q, Jiao S, Luo L, Ding MS, Zheng J, Cartmell SS, et al. Wide-Temperature Electrolytes for Lithium-Ion Batteries. ACS Appl Mater Interfaces 2017;9:18826–35. https://doi.org/10.1021/acsami.7b04099. [2] Ng B, Coman PT, Faegh E, Peng X, Karakalos SG, Jin X, et al. Low-Temperature Lithium Plating/Corrosion Hazard in Lithium-Ion Batteries: Electrode Rippling, Variable States of Charge, and Thermal and Nonthermal Runaway. ACS Appl Energy Mater 2020;3:3653–64. https://doi.org/10.1021/acsaem.0c00130. [3] Li J, Li S, Zhang Y, Yang Y, Russi S, Qian G, et al. Multiphase, Multiscale Chemomechanics at Extreme Low Temperatures: Battery Electrodes for Operation in a Wide Temperature Range. Adv Energy Mater 2021;11. https://doi.org/10.1002/aenm.202102122.

The growing threat of airborne biological agents necessitates rapid, sensitive, and portable detection systems to mitigate risks to public health and national security. We present a comprehensive overview of biosensor technologies developed for airborne biothreat detection, with a focus on aptamer-based electrochemical sensors. These sensors offer key advantages in portability, chemical stability, and adaptability for multiplexed detection in field settings. The urgency for real-time surveillance tools capable of identifying viral, bacterial, and toxin-based agents is discussed, particularly in the context of biodefense. Aerosolized particle capture strategies are reviewed, focusing on microfluidics for micron-sized particles and condensation-based systems for submicron-sized particles, which are preferred for their small-volume operation and seamless integration with biosensors. Key biosensor components are described, including recognition elements-such as aptamers-and transduction mechanisms like electrochemical impedance spectroscopy. EIS is highlighted for its label-free, miniaturizable, and real-time readout capabilities, making it well-suited for portable biosensors. Advances in sensing strategies for both viral and bacterial targets are explored, featuring innovations in nanoporous membrane platforms, nanomaterials, and multiplexed assay formats. Recent developments demonstrate improved sensitivity through nanopore-based signal amplification and enhanced selectivity using engineered aptamer libraries. The review concludes by addressing current limitations, including environmental stability, system integration, and the need for validation with complex real-world samples. Future directions point toward the development of fully integrated, field-deployable biosensing platforms that combine effective aerosol capture with robust and selective biosensing technologies.