Laboratory Directed Research And Development Research Articles

Designing a Stable and Electrically Conductive Colloidal Suspension for Improved Flow Electrode Capacitive Deionization

With increasing effects from major droughts and water shortages, water desalination has garnered significant technological interest. Like many technologies, desalination suffers from high energy consumption, capital cost, process inefficiencies, and material degradation. Flow electrode capacitive deionization (FCDI) is a relatively new water desalination technology that combines aspects of electrodialysis and capacitive deionization to deliver a device which can achieve >90% water recovery at high productivity and thermodynamic efficiency. A fundamental challenge in FCDI, though, is engineering an electrically conductive slurry with excellent colloidal stability. Here, we explore the tradeoff between electrical conductivity and sedimentation rate using commercially available surfactants. We find that the optimal surfactant is non-intuitive and strongly depends on the type of carbon used in the slurry (e.g., activated carbon, carbon black, etc.).This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant #22-DR-011. IM release number: LLNL-ABS-846651.

Improving the Durability and Performance of Anion Exchange Membranes for Water Electrolyzers

The two major drawbacks of most renewable sources are intermittency and availability. Renewables will naturally need to be efficiently integrated with electrochemical methodologies for storage (batteries), conversion (fuel cells) and application (electrolysis, CO2 reduction reactions). Alkaline anion exchange membranes (AAEM) have attracted considerable interest to navigate some of the economic hurdles native to polymer electrolyte membrane-based technologies. Despite many advances over the past decade, AAEM long-term stability towards hydroxide mediated degradation remains a significant challenge. Here we integrate anion exchange membrane synthesis, accelerated stress testing and characterization (structural, chemical, electrochemical) to understand and mitigate the effect of degradation of AAEM under electrochemical conditions on the performance of these materials.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 21-ERD-013. IM # LLNL-ABS-846373

Grooved Electrodes for High Power Density Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) are a promising alternative to internal combustion engines, owing to their intrinsic power density, decoupled energy storage and generation, and relatively short refueling time. However, challenges related to cost, performance, and durability continue to prevent wide adoption of PEMFCs.1 Development of alternative electrode structures, which can enable smaller and less expensive PEMFCs with higher power and lower precious metal content, provides a promising path to overcome these challenges.2 Here, we report grooved electrodes, where the transport pathways of H+ and O2 were partitioned. Specifically, H+ are transported through electrode ridges with optimized ionomer content, and O2 is transported through the grooves that separate the electrode ridges. The grooved electrodes made with commercial electrode materials enhanced the performance up to 50%, and the enhancement becomes greater after accelerated durability tests. We verify via electrochemical impedance analyses, limiting current measurements, and multiphysics modeling that the enhancement is due to improved H+ and O2 transport. The work also demonstrates that the electrodes can be further improved by optimizing the electrode geometry, proven via machine learning investigations. These results inform next generation electrode designs for enhanced PEMFC performance and durability. Acknowledgement: This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) through the Million Mile Fuel Cell Truck (M2FCT) consortia, technology managers G. Kleen and D. Papageorgopoulos. Financial support for this work from the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) is gratefully acknowledged (Projects 2020200DR and 20210915PRD2). ChungHyuk Lee acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC).

Highly Robust Fuel Cell Electrodes Using Pt Thin Film Catalysts As Reversal Tolerant Anodes

Recent years have seen a rise in interest in polymer electrolyte membrane fuel cells (PEMFCs) because of its high power density, high energy efficiency, and zero-emission characteristics. PEMFC-powered fuel cell electric vehicles (FCEVs) have the potential to significantly lower the transportation sector's carbon dioxide emissions, paving the way for the global adoption of the hydrogen economy. However, the durability and robustness of fuel cell systems must be increased before a wider commercialization of FCEVs is possible. The hydrogen starvation in anode, occurring during start-up/shutdown or cold start, can cause rapid and significant deterioration of the performance and durability of a PEMFC system through cell reversal. In hydrogen-starved conditions, the cell's performance can deteriorate in just a few minutes, leading to sudden cell failure. Prior studies have been conducted to understand the degradation caused by hydrogen starvation and cell reversal in PEMFCs, with the aim of identifying mitigation solutions that could minimize deterioration of membrane electrode assembly (MEA) components. In this work, we present a novel materials strategy to mitigate cell damage using a thin film Pt anode catalyst supported on Nafion nanowires in a co-axial configuration. Due to the high roughness of Nafion nanowire, the coaxial nanowire electrode (CANE) negates the needs for conventional carbon support and displays exceptional robustness to reversal tolerance. This work will present a systematic evaluation of CANE as reversal tolerant anodes compared to conventional supported catalyst (Pt/C). Further enhancement in durability by integration of iridium with CANE anode will also be presented. Acknowledgement This research was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) through the Million Mile Fuel Cell Truck (M2FCT) consortia, technology managers G. Kleen and D. Papageorgopoulos. Authors would also like to acknowledge support for this work from the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) (2020200DR).

Exploring the Use of Static Mixers for Enhanced Flow-Electrode Capacitive Deionization

Water desalination plays a major role in alleviating water scarcity issues, but it faces major barriers due to high energy use, low water utilization, and significant environmental impacts. Flow electrode capacitive deionization (FCDI) is a new ultra-efficient electrochemical water treatment technology capable of desalinating saline streams (e.g., brackish water, seawater) with less than 10% of the feed water rejected as waste. Here we use a structured flow plate design to maximize charge transfer while incurring a negligible pressure drop penalty. Different 3D printed flow plate structures were characterized individually in a flow capacitor arrangement to quantify their relative merits in terms of the tradeoff between conductivity and flow characteristics with carbon slurries containing 5-9 wt% activated carbon and 0-1 wt% carbon black.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 22-DR-011. IM #LLNL-ABS-846456

Improved Iron Flow Battery Designs for Low-Cost Grid Storage

To achieve grid-scale energy security through widespread deployment of flow batteries we need to rapidly advance low-cost, scalable, and durable technologies. Even though, earth-abundant iron-based technologies offer low-cost storage solutions projecting levelized cost for storage >$0.05/kWh, durability is yet a major issue hindering the commercialization.Hybrid nature of the system is also another barrier to achieve energy-dense scalable systems compared to all soluble flow batteries. Our present study focuses on understanding the factors affecting long-term durability of the full-cell device and overcoming them by improving electrolyte properties, key reactor components including membrane separators and electrode structures and the kinetics of metal deposition/ dissolution process.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 22-DR-014. IM release number: LLNL-ABS-847140.

Enhanced Durability of Nickel-Based Electrocatalysts for Oxygen Evolution Reaction (OER) at High Current Densities Using External Stimulation

Hydrogen (H2) is one of the most promising energy carriers for future clean energy production. The cleanest method to produce H2 is by water electrolysis using renewable electricity. Among electrolysis technologies, alkaline water electrolysis (AWE) is significantly cheaper than other techniques. While AWE is cost effective, it suffers from low power densities due to limited electrochemical stability at high current densities. Most stability challenges arise from anode degradation, where the oxygen evolution reaction (OER) occurs. The OER is key to achieve economic viability of AWE and current state-of-the-art electrocatalysts for OER are costly and scarce. Nickel-based catalysts are inexpensive, earth-abundant, and exhibit high OER performance but still exhibit durability challenges under high current densities. While several approaches have been reported to enhance durability of these catalysts, they are often complicated and time-consuming. We present a novel and simple method through which external stimulation can be used to enhance the durability of single metal catalysts. In this work, the durability of nickel-based electrocatalysts for OER under alkaline conditions (1 M NaOH) at high current densities was evaluated as a function of external stimulation in a chemically stable custom electrochemical cell. This cell was fabricated using additive manufacturing (AM), which enabled the direct application of external stimulation onto nickel-based materials in the cell. In addition, the performance of the electrocatalysts at high OER current densities for extended periods of time was measured as a function of various external stimulation parameters. Acknowledgements Financial support from the Los Alamos National Laboratory, Laboratory-Directed Research and Development (LDRD) is gratefully acknowledged. The authors would also like to thank the NNSA Minority Serving Institutes Partnership Program and LANL: Under-Represented Minority Partnership Program for their funding support. References Vij, Varun, et al. "Nickel-based electrocatalysts for energy-related applications: oxygen reduction, oxygen evolution, and hydrogen evolution reactions." Acs Catalysis10 (2017): 7196-7225.Foroughi, Faranak, et al. "Understanding the Effects of Ultrasound (408 kHz) on the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) on Raney-Ni in Alkaline Media." Ultrasonics Sonochemistry 84 (2022): 105979.Foroughi, Faranak, et al. "Sonoactivated polycrystalline Ni electrodes for alkaline oxygen evolution reaction." Ultrasonics Sonochemistry 86 (2022): 106013.

SARS-CoV-2 variant transition dynamics are associated with vaccination rates, number of co-circulating variants, and convalescent immunity

Throughout the COVID-19 pandemic, the SARS-CoV-2 virus has continued to evolve, with new variants outcompeting existing variants and often leading to different dynamics of disease spread. In this paper, we performed a retrospective analysis using longitudinal sequencing data to characterize differences in the speed, calendar timing, and magnitude of 16 SARS-CoV-2 variant waves/transitions for 230 countries and sub-country regions, between October 2020 and January 2023. We then clustered geographic locations in terms of their variant behavior across several Omicron variants, allowing us to identify groups of locations exhibiting similar variant transitions. Finally, we explored relationships between heterogeneity in these variant waves and time-varying factors, including vaccination status of the population, governmental policy, and the number of variants in simultaneous competition. This work demonstrates associations between the behavior of an emerging variant and the number of co-circulating variants as well as the demographic context of the population. We also observed an association between high vaccination rates and variant transition dynamics prior to the Mu and Delta variant transitions. These results suggest the behavior of an emergent variant may be sensitive to the immunologic and demographic context of its location. Additionally, this work represents the most comprehensive characterization of variant transitions globally to date. Laboratory Directed Research and Development (LDRD), Los Alamos National Laboratory.

Effect of Cobalt Cation Concentration on PEMFC Electrode Performance

Metal alloy catalysts, such as Pt-Co, reduce the activation energy of oxygen reduction reaction, leading to improved proton exchange membrane fuel cell (PEMFC) performance. However, leaching of non-noble elements contaminates the ionomer and membrane, which has a negative impact on the durability of PEMFCs [1,2]. For the commercial success of metal alloy catalysts, understanding the mechanisms of how cation contamination affects PEMFC performance is crucial. Here, we investigate the effect of cobalt cation contamination effects through intentional doping of decal electrodes. Electrochemical testing results are coupled with membrane conductivity and water uptake measurements, as well as impedance modeling to identify the mechanisms of performance loss. Our results provide a comprehensive understanding of how cation contamination affects performance, which can inform mitigation strategies and new materials development that can enable the use of metal alloy catalysts in PEMFCs. Acknowledgement This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) through the Million Mile Fuel Cell Truck (M2FCT) consortia, technology managers G. Kleen and D. Papageorgopoulos. Financial support for this work from the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) is gratefully acknowledged (Projects 2020200DR and 20210915PRD2). ChungHyuk Lee acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC). References Cai et al., ECS Trans., 69, 1047 (2015)P. Braaten et al., J. Electrochem. Soc., 166, F1337 (2019) Figure 1

(2021-2022 ECS Toyota Young Investigator Fellowship) Understanding and Suppression of Cation Transport into Polymer Electrolyte Membrane Fuel Cell

Polymer electrolyte membrane fuel cells (PEMFCs) are a viable zero-emissions option for the electrification of the heavy duty transportation sector. However, PEMFCs still suffer from degradation of materials over the fuel cell lifetime. Cation contaminants can be generated from corrosion of bipolar plates and balance of plant components, water contaminants, and environmental sources (e.g., Fe3+, Ca2+, Na+), making them present in the fuel or oxidant stream during operation(1). Cations have been shown to be detrimental to the performance of the PEMFC by reducing water uptake, ionic conductivity, and O2 transport, resulting in performance loss and degradation. Metal cations such as Fe3+ can also lead to chemical degradation of the membrane ionomer (2-4). It is critical to understand the mechanism and rate of cation transport from the bipolar plate channel to the membrane to develop mitigation strategy to suppress the cation transport.In this work, we present the study of the cation (Fe3+) transport mechanism through the gas diffusion layer (GDL) by introducing a cation solution in the cathode channel. Transport rates across the GDL are studied using an ex-situ GDL holder where Fe solution is introduced in the GDL substrate side with water transported through to the microporous layer side (MPL) and is collected and analyzed for Fe concentration, as shown in Figure 1a. Effect of the Fe concentration on transport rates is also studied using computational modeling. Understanding of the transport mechanism is then leveraged to identify mitigation solutions and suppress cation transport from the flow field to the electrode using a GDL with dual MPL architecture as shown in Figure 1b. Optimization of the dual MPL architecture for both durability and performance is also presented. Acknowledgements This research is supported by the 2021-2022 ECS Toyota Young Investigator fellowship and U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT). Authors acknowledge the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL). References D. D. Papadias, R. K. Ahluwalia, J. K. Thomson, H. M. Meyer, M. P. Brady, H. L. Wang, J. A. Turner, R. Mukundan and R. Borup, Journal of Power Sources, 273, 1237 (2015).R. K. Ahluwalia, D. D. Papadias, N. N. Kariuki, J. K. Peng, X. P. Wang, Y. F. Tsai, D. G. Graczyk and D. J. Myers, Journal of the Electrochemical Society, 165, F3024 (2018).J. P. Braaten, X. M. Xu, Y. Cai, A. Kongkanand and S. Litster, Journal of the Electrochemical Society, 166, F1337 (2019).A. Kneer, J. Jankovic, D. Susac, A. Putz, N. Wagner, M. Sabharwal and M. Secanell, Journal of The Electrochemical Society, 165, F3241 (2018). Figure 1

(Invited) Transient Absorption and Compressive Sensing for Understanding Dynamics in Photocatalytic Nanoparticles and Energy Conversion Materials

Transient absorption (TA) is a well-known tool for understanding the dynamical response of materials following the absorption of a photon. TA allows the dynamics of photoinduced energy flow and energy conversion to be monitored, along with other competing dissipative processes. With current technologies, TA can provide dynamical information over the ultraviolet, visible, near-infrared, mid-infrared, and terahertz spectral ranges, which allows the study of a concomitant range of photoinduced processes of relevance to photocatalysis. However, since TA usually involves very small changes in absorption, the approach can be quite time consuming and, as a result, signal averaging for hours is not uncommon. In addition to time limitations, long signal averages are challenging for many materials, including photocatalytic systems, because many materials degrade under long periods of laser illumination. Longer experiments also place greater demands on the stability of lasers, usually leading to the need for environmental controls, which adds cost and complexity to TA spectroscopies. Thus, there are several important reasons to increase the speed of TA as long as accuracy and sensitivity can be maintained.In this talk, I present recent efforts to dramatically decrease the time needed to perform TA through compressive sensing, whereby a smaller number of data points are randomly collected over the chosed dynamical range of the TA experiment.[1] The general principle works well when the transformation of the optical signal to another domain has a low density of TA features. Studies and applications to colloidal plasmonic nanoparticles, such as nanostructures made of refractory materials, and energy conversion materials are shown. I also present imaging efforts using femtosecond optical pulses in scattering environments where conventional imaging is difficult.[2] By utilizing enhanced second harmonic generation from high peak-power ultrashort pulses, combined with compressive sensing approaches, successful reconstruction of optical images can be undertaken.Work performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This material is based on work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357. References Adhikari, S., Cortes, C. L., Wen X., Panuganti, S., Gosztola, D. J., Schaller, R. D., Wiederrecht, G. P., Gray, S. K., “Accelerating ultrafast spectroscopy with compressive sensing,” Phys. Rev. Appl., Vol. 15, 024032, 2021.Wen, X., Adhikari, S., Cortes, C. L., Gosztola, D. J., Gray, S. K., Wiederrecht, G. P., “Ghost imaging second harmonic generation microscopy,” Appl. Phys. Lett., Vol. 116, 191101, 2020.

Corrosion Mechanisms in Additively Manufactured 316L Stainless Steels

Additively manufactured 316L stainless steels (316L SS) using laser powder bed fusion technique (L-PBF) exhibit an excellent combination of high strength and ductility compared to the conventional counterpart. The outstanding material mechanical properties originate from the sub-grain cellular structures developed during the rapid solidification inherent to L-PBF. These structures consist of elongated cells decorated by high density of dislocations, trapped solute, and fine precipitates at their boundaries. The impact of such cellular structures on corrosion resistances, however, remains incompletely understood. In addition, the L-PBF process leads to high surface roughness and usually around 0.1 to 0.5% of porosity. However, the pitting potential of the L-PBF 316L SS can be an order of magnitude higher than the conventional, well annealed counterpart.In this talk, we will first present a detailed multi-scale characterization of the microstructural features unique to L-PBF 316L SS. In a second part, we will present our experimental-simulation integration approach where we combine surface chemistry mapping and electron and atomic force microscopy with multi-scale simulations to understand the effect of local microstructure variations on pitting and metal dissolution rates in NaCl and HCl environments.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Authors acknowledge the support of the Laboratory Directed Research and Development (LDRD) program (20-SI-004) at LLNL.

(Invited) Exploring the Potential of Machine Learning and AI for ALD Process Optimization

Over the past years there has been a surge of interest on the application of machine learning, and more broadly, artificial intelligence, to scientific applications. This interest has been spurred by an advancement of our computational capabilities coupled with the development of a large set of methods and machine learning frameworks to carry out complex analysis of large datasets in ways that were not possible in the past. In this presentation, I will explore the application of machine learning techniques to the area of atomic layer deposition, and in particular to process optimization. While most ALD processes are highly reproducible, the optimization of both new and existing ALD processes in novel reactors is often time consuming and labor intensive. This motivated us to search for ways of accelerating this task using both ex-situ and in-situ experimental data that is readily available in many laboratories.First, I will focus on the development of surrogate models that can predict the saturation dose times based on partially saturated growth profiles, a type of data that is part of the routine characterization of ALD processes in many labs. In order to develop this surrogate model, we first created a dataset using simulated data providing growth profiles across one of our ALD reactors for a wide range of possible experimental conditions, including precursor pressure, surface reactivity, growth per cycle, flow conditions, and dose times. We then used this dataset to train deep neural networks to predict the dose time that would lead to complete saturation. By tailoring the complexity of the model, the number of growth profiles per condition, and the structure/depth of the neural network we can explore the minimum number experiments and data points required to accurately predict saturation for an unknown ALD process. Our results show that for the optimization of a single precursor, neural networks can accurately predict saturation times using just a single growth profile and its corresponding dose time as an input.Then, I will focus on the use of in-situ techniques for the automatic optimization of ALD processes without a human in the loop. The advantage of using in-situ techniques is that they can provide a much faster response, reducing optimization times by more than two orders of magnitude. Using a realistic model of a single quartz crystal microbalance, we have developed both expert systems and Bayesian optimization-based models that are capable of exploring the process conditions and converge on optimal conditions leading to saturation. We then implemented the expert system model in one of our experimental reactors, experimentally validating this approach. This methodology can be expanded to other in-situ techniques, such as spectroscopic ellipsometry, or more sophisticated arrangement including more than one probe to obtain spatially dependent data.Finally, I will briefly discuss other potential applications of machine learning, for instance for process optimization using spatial ALD configurations, or to predict the self-limited nature of novel processes.This material is based upon work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-06CH11357.

Membrane-Electrode-Assembly Design Parameters and Their Impact on CO2 Reduction

CO2 electrolyzers that operate at high current densities and selectivities are essential for commercializing CO2 electroreduction and for a sustainable, CO2-neutral green energy paradigm. As part of this, membrane-electrode assemblies (MEAs) are critical components that enable industrial-scale electrochemical CO2 conversion to value-added fuels and chemicals. They consist of humidified gaseous feeds at one or both electrodes and a solid, ion-conducting polymer (ionomer) as the electrolyte. Such assemblies can overcome the experimentally observed ohmic and mass-transfer limitations characteristic of aqueous gas-diffusion electrode (GDE) and planar systems, respectively, which limit their maximum achievable current densities and render these systems impractical for industrial implementation.Foundational design parameters that characterize the ionomer-based catalyst layers unique to MEA systems include the ionomer-to-catalyst (I:Cat) ratio, the catalyst loading, and the catalyst layer thickness. In this talk, the results of a comprehensive experimental study on a Ag-cathode CO2 reduction (CO2R) MEA will be reported, where we systematically analyzed the effects of these design parameters on CO2R MEA performance and selectivity. An optimum, intermediate I:Cat ratio was uncovered and rationalized based on electrochemically-active surface area and ionomer distribution arguments. The effect of decreasing the catalyst loading and/or thickness corroborates previous modeling work, resulting in an optimum range for catalyst layer utilization for CO2R. The effect of MEA anolyte/exchange solution concentration on system performance is also explored, yielding an efficient Ag-cathode CO2R MEA that operates at 200 to 1000 mA/cm2, at CO FEs of 78 to 91%, and with an area-specific resistance of 1 Ω*cm2.The scientific and experimental design learnings from our Ag-cathode MEA studies are subsequently applied to a Cu-cathode MEA, which has farther reaching and impactful applications due to its ability to produce value-added chemical precursors like ethylene and ethanol. The Cu-MEA cathodic I:Cat ratio and catalyst loading are fixed based on settings from the optimized Ag-MEA and additional catalyst layer parameters and operating conditions are examined. This systematic exploration provides deeper insights into the underlying interrelationships between physical phenomena in the Cu-MEA system. Overall, these studies provide a fundamental understanding of the relationships between critical design parameters and inherent operating and materials tradeoffs for practical CO2 reduction devices. Acknowledgements The authors gratefully acknowledge Lawrence Berkeley National Laboratory’s Laboratory Directed Research and Development (LDRD) Grant for funding.

Excess Deaths Reveal the True Spatial, Temporal, and Demographic Impact of COVID-19 on Mortality in Ecuador

Background: In early 2020, Ecuador reported one of the highest surges of per capita deaths across the globe.Method: We collected a comprehensive dataset containing individual death records between 2015 and 2020 from the Ecuadorian National Institute of Statistics and Census and the Ecuadorian Ministry of Government. We computed the number of excess deaths across time, geographical locations and demographic groups using Poisson regression methods.Findings: Between January 1st and September 23rd, 2020, the number of excess deaths in Ecuador is 36,402 (95% CI: 35,762-36,827) or 208 per 105 population, which is 171% of the expected deaths in that period in a typical year. Only 20% of the excess deaths are attributable to confirmed COVID-19 deaths. Strikingly, in provinces that were most affected by COVID-19, such as Guayas and Santa Elena, the all-cause deaths are more than double the expected number of deaths that would have occurred in a normal year. The extent of excess deaths in men is higher than in women, and the number of excess deaths increases with age. Indigenous populations had the highest level of excess deaths among all ethnic groups.Interpretation: Overall, the exceptionally high level of excess deaths in Ecuador highlights the enormous burden and heterogeneous impact of COVID-19 on mortality especially in older age groups and indigenous populations in Ecuador that was not fully revealed by COVID-19 death counts. Together with the limited testing in Ecuador, our results suggest that the majority of the excess deaths were likely to be undocumented COVID-19 deaths.Funding: The work is partially funded by the Laboratory Directed Research and Development (LDRD) Rapid Response Program through the Center for Nonlinear Studies at Los Alamos National Laboratory, and LDRD grants 20200699ER and 20210709ER. RK and SP would like to acknowledge funding from DARPA (HR0011938513), the Center for Nonlinear Studies. ERS was funded though NIH grant (R01AI135946).Conflict of Interest: We declare no competing interests.Ethical Approval: Ethics committee approval was obtained from the Ecuadorian Ministry of Public Health. The analysis by Los Alamos National Laboratory team was approved by that institution’s IRB.

Understanding the Role of Electrochemically Inactive Substituent in Layered Oxide Cathode Materials for Advanced Sodium Ion Batteries

The importance of electrochemical energy storage systems for large-scale application has been growing increasingly over the last decades. Due to high cost, limited source and several technical barriers of the lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) are considered as one of promising candidates for large-scale energy storage systems based on their cost-effective, earth abundant and recyclable characteristics.[1] As promising cathode materials for SIBs, P2-type sodium iron manganese oxide with layered structures (Na x Mn y Fe1-y O2, 0.5 < x < 0.8) demonstrates similar high energy density analogous to the LiBs.[2] However, the capacity retention of the cell with layered structure cathode is not optimized especially when it is charged and discharged with wide voltage window to obtain higher capacity. The major reason for this is a phase transition induced by gliding of transition metal slabs, which causes irreversible structural changes gradually during cycling.[3]To address this phase transition issue, we introduce electrochemically inactive component (e.g., Mg2+) in the material. The introduction of the Mg2+ by substituting with existing transition metal(s) is able to provide improved capacity retention due to their enhanced structural stability. We systematically analyzed the capacity fading trends at high and low voltage regions, where each different transition metal dominantly contributes to the redox reactions, which provides mechanistic understanding of the structural degradation of P2-type NaxMnyFe1-yO2 and the effect of Mg2+ on transition metal redox behaviors. In addtion, by tracing the structural changes in the cathode, we demonstrated that the introduction of Mg2+ effectively abbreviates the unwanted phase transitions. The results can provide the insights of the phase transition mechanism and redox behaviors of layered type cathode materials and the strategies to stabilize the structure by employing electrochemically inactive substituent(s), thus enabling rational design of new cathode materials for the development of next generation SIBs.[1] M. D. Slater, D. Kim, E. Lee, C. S. Johnson, Adv. Funct. Mater. 23 (2013) 947-958.[2] C. Delmas, C. Fouassier, P. Hagenuller, Physica B+C 99 (1980) 81-85.[3] E. Talaie, V. Duffort, H. L. Smith, B. Fultz, L. F. Nazar, Energy Environ. Sci., 5 (2015) 2512. Acknowledgement J. Yang and S.-D. Han acknowledge funding support by the Laboratory Directed Research and Development (LDRD) program at National Renewable Energy Laboratory (NREL).The work done at Brookhaven National Laboratory was supported by Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. DOE, through the Advanced Battery Materials Research (BMR) Program under contract DE-SC0012704.

KG-COVID-19: A Framework to Produce Customized Knowledge Graphs for COVID-19 Response

Integrated, up-to-date data about SARS-CoV-2 and coronavirus disease 2019 (COVID-19) is crucial for the ongoing response to the COVID-19 pandemic by the biomedical research community. While rich biological knowledge exists for SARS-CoV-2 and related viruses (SARS-CoV, MERS-CoV), integrating this knowledge is difficult and time consuming, since much of it is in siloed databases or in textual format. Furthermore, the data required by the research community varies drastically for different tasks - the optimal data for a machine learning task, for example, is much different from the data used to populate a browsable user interface for clinicians. To address these challenges, we created KG-COVID-19, a flexible framework that ingests and integrates biomedical data to produce knowledge graphs (KGs) for COVID-19 response. This KG framework can also be applied to other problems in which siloed biomedical data must be quickly integrated for different research applications, including future pandemics.Funding: This work was supported by grants from the Director, Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy [to J.R., D.U., S.C., N.L.H., M.J., C.J.M], the Laboratory Directed Research and Development (LDRD) Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231, the NIH (Monarch R24 OD011883, Illuminating the Druggable Genome U01 CA239108-01), a Training Grant from the NLM, NIH to the University of Colorado Anschutz Medical Campus Computational Bioscience Training Program [T15LM009451 to T.J.C.], the National Virtual Biotechnology Laboratory (NVBL), and the Google Cloud COVID-19 Research Grants program. Conflict of Interest: The authors declare no competing interests.

Effect of Substituents on the Activity of Organic Molecular Electrocatalysts for Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) is a fundamental and critical process that enables H2 production through electrochemical water splitting. Conventional HER catalysts are based on metal-containing materials in which the metal atoms function as the catalytic centers. Recently, we demonstrated a metal-free organic molecular electrocatalyst (OMEC) for HER in acidic media with high activity and durability.1, 2 This OMEC is based on a small pyridine-based heterocycle. A density functional theory (DFT) study of the HER mechanism catalyzed by this molecule revealed that the thermodynamic limiting potential is related to the atomic hydrogen adsorption energy at the pyridyl-N site.1, 2 Further, our systematic study of the substituent effects on the proton-coupled electron transfer (PCET) potential at nitrogen-containing heterocycles provided guidance to the rational design of OMECs for HER.3 In this talk, we will present a study on the substituent effects on the activity of the organic molecular electrocatalyst mentioned above.1,2 Several substituents with electron-withdrawing/donating character will be included in this study. The HER activity of these substituted molecules is determined experimentally through electrochemical measurement. Their HER onset potentials are further correlated with the H adsorption energy values at pyridyl-N sites predicted from DFT calculations. Through the combined experimental-computational approach, we demonstrate the structure-activity relationship within this particular type of OMECs, guiding future OMEC research. Acknowledgments Financial support for this research by Los Alamos National Laboratory through Laboratory Directed Research and Development (LDRD) Exploratory Research (ER) program is gratefully acknowledged. References X. Yin, L. Lin, H. T. Chung, U. Martinez, A.M. Baker, S. Maurya, P. Zelenay. Organic Molecular Catalyst for Hydrogen Evolution Reaction, Meeting s, The Electrochemical Society, MA2017-02, 1659 (2017).X. Yin, L. Lin, U. Martinez, H. T. Chung, P. Zelenay. Bifunctional Organic Molecular Electrocatalyst for Hydrogen Evolution Reaction and Hydrogen Peroxide Production, Meeting s, The Electrochemical Society, MA2018-02, 1609 (2018).X. Yin, E. F. Holby, P. Zelenay. Structure-Activity Data Mining for Hydrogen Evolution Reaction at Organic Molecular Electrocatalysts, Meeting s, The Electrochemical Society, MA2019-01, 1429 (2019).

New Reference Electrodes for Air and Moisture Stable Ionic Liquids

The use of room temperature ionic liquids (RTILs) for electrochemical applications such as fuel cells, batteries, dye-sensitized solar cells, and supercapacitors, has gained significant interest over the last decade. Despite the increase in attention, a universal reference electrode for use in RTIL electrochemistry has not been adopted. A stable, easy to prepare, and reproducible reference electrode, analogous to Ag/AgCl reference electrodes for aqueous electrochemistry, is crucial for accurately determining redox potentials as well as for comparing these potentials between RTILs and between research labs. Electrochemical work in RTILs often rely on quasi-reference electrodes (QREs),1 such as Ag or Pt wire, which must be calibrated by the addition of a redox couple (e.g. ferrocene/ferrocenium) after each electrochemical measurement. These quasi-reference electrodes are difficult to reproduce, likely due to the quality of the wire used and the presence of surface adsorbates. Furthermore, they have been known to exhibit potential drift during use, with 10s to 100s of mV drift often observed. Ferrocene is added after the experiment, however this one-point calibration of the QRE does not necessarily apply throughout the entire experiment, as the QRE may drift during the measurement.2 We report on reference electrodes designed for use in ionic liquids, which exhibit stable potential over several months of experimental use. One successful example is based on a silver wire coated with silver sulfide.3 The reference electrode potential is determined by the concentrations of Ag+ and S2 −, which are established by the solubility of the Ag2S coating on the Ag wire. Our reference electrode can be prepared and used in a normal air atmosphere, and does not need to be assembled and used in a glovebox, or protected from light. The reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five RTILs investigated over the course of 2+ months. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-047. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release LLNL-ABS-748348. (1) Electrochemical aspects of ionic liquids, 2nd ed.; Ohno, H., Ed.; John Wiley & Sons Inc., 2011. (2) Torriero, A. A. J.; Sunarso, J.; Howlett, P. C. Electrochim. Acta 2012, 82, 60–68. (3) Horwood, C.; Stadermann, M. Electrochem. commun. 2018, 88, 105–108.

Investigation of Metal Ion Diffusion and Reduction Potential in Several Ionic Liquids

Electrodeposition is proving to be a promising technique for forming metal capsules and other components required for Inertial Confinement Fusion (ICF) experiments performed at the National Ignition Facility. While we have recently demonstrated that non-porous, defect free parts can be electrodeposited from a variety of water-based solutions,1,2 many of the preferred metals for the ICF program (beryllium, uranium, etc.) cannot be deposited because electrolysis of water occurs at the potential required to reduce such metals. To circumvent this, we are currently investigating Ionic Liquids (ILs) as solvents for metal electrodeposition, as the wide (~ 6 V) electrochemical window of ILs is expected to allow electrodeposition of Be, U, and many other metals.3 We are investigating the key parameters of metal ion diffusion and reduction potential for two model metals, silver and copper, in several different ionic liquids. We use electrochemical measurements along with first principles density functional theory (DFT) simulations to understand how ionic liquids affect diffusion and reduction potential, and this understanding will be applied to selecting appropriate ILs for deposition of metals such as Be and U. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-047. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release LLNL-ABS-771850. (1) Horwood, C.; Stadermann, M.; Bunn, T. L. Fusion Sci. Technol. 2018, 73 (3). (2) Bunn, T.; Horwood, C.; Stadermann, M. Cathode System for Electrodeposition of Metals on Microspheres. US Patent 16336-000075-US-PS1, 2018. (3) Electrodeposition from ionic liquids, 2nd ed.; Endres, F., Abbott, A., MacFarlane, D., Eds.; Wiley-VCH: Weinheim, Germany, 2017.