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All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Operando bulk and interfacial characterization for electrochemical energy storage: Case study employing isothermal microcalorimetry and X-ray absorption spectroscopy

Abstract The global shift to electricity as the main energy carrier will require innovation in electrochemical energy storage (EES). EES systems are the key to the “electron energy economy,” minimizing losses and increasing reliability between energy supply and demand. However, steep challenges such as cost, cycle/calendar life, energy density, material availability, and safety limit widespread adoption of batteries for large-scale grid and vehicle applications. Battery innovation that meets today’s challenges will require new chemistries, which can originate from understanding charge transport phenomena at multiple time and length scales. The advancement of operando characterization can expedite this progress as changes can be observed during battery function. This article highlights progress in bulk and interfacial operando characterization of batteries. Specifically, a case study involving Fe 3 O 4 is provided demonstrating that combining X-ray absorption spectroscopy and isothermal microcalorimetry can provide real-time characterization of productive faradaic redox processes and parasitic interfacial reactions during (de)lithiation. Graphic abstract

36 MATERIALS SCIENCE↗
DOE OSTI2024

High Refractive Index Adhesives for Laser Glass Cladding Applications (ABBREVIATED Report)

To eliminate parasitic light oscillations (amplified spontaneous emission (ASE)), high energy laser systems often utilize polymeric materials to adhere optically absorptive cladding materials to laser gain media (glass or crystal). Most of these polymeric optical adhesives are index matched to lower index gain media, and there was no capability to achieve refractive indices (RI) greater than 1.60 with low color, while also maintaining mechanical compliance to serve as adhesives for cladding applications. The completion of LDRD 23-FS-043 shows we can chemically develop novel suitable adhesive candidates with refractive indices above 1.64 at 532 nm while also exhibiting Shore A hardness between 50-90, with high optical clarity, low color, and minimal haze for films ~1-2 mm thick (84 %Transmission at 532 nm). This will enable us to begin mapping a process space to allow future customizable adhesive formulations for building a variety of laser systems with tunable refractive index matching for various gain and cladding media.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A model investigation of the impact of lower hybrid wave scattering angle on current drive profile in EAST and Alcator C-Mod

Lower hybrid current drive (LHCD) is beneficial for developing a steady-state operation scenario in a tokamak. This paper conducts a modeling investigation to identify an optimum rotation angle of the initial lower hybrid perpendicular (to the background magnetic field $\overrightarrow{B}$) wavevector for best matching the experimental RF current profile. It is hypothesized that central RF power deposition widely observed in the present-day LHCD experiments arises from wave scattering by turbulence. In a standard model without considering such interactions, the predicted power deposition profile is generally broad with off-axis peaking, not in agreement with experimental observations. A heuristic approach is adopted by introducing a spectral broadening mechanism by modifying the initial orientation of the perpendicular wavevector. The ray-tracing/Fokker–Planck solver GENRAY/CQL3D is utilized within the python-based π-scope framework. A focus is given to identify the perpendicular wavenumber orientation angle with respect to the magnetic surface normal vector at the initial ray location. Our modeling study shows that rotating the perpendicular wavevector in such a way as to increase the initial poloidal component is effective in reproducing the centrally peaked current profile observed in normal shear plasmas on both EAST and C-Mod. These waves can readily be absorbed to the central plasma, which reduces the sensitivity of the power deposition profile to a slight change of the plasma condition. The same approach is also found to help broaden the off-axis power deposition profile in a reverse-shear EAST plasma, leading to a better agreement with the experiment. The results presented here suggest that spectral modification arising from edge density fluctuations in a tokamak may need to be considered in understanding wave propagation and absorption. A further experimental and theoretical/modeling study is vital as a reverse approach is adopted in this study. Finally, our work suggests that mitigation or control measures are critical for parasitic effects occurring on the first pass in a reactor regime.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

A ruthenium oxide thermometer for dilution refrigerators operating down to 5 mK

At the lowest temperatures achieved in dilution refrigerators, ruthenium oxide resistance thermometers often saturate and therefore lose their sensitivity. In an effort to extend the range of such temperature sensors, we built a thermometer which maintains sensitivity to 5 mK. A key component of this thermometer is an in situ radio frequency filter which is based on a modern rf absorption material. Here, we show that the use of such a filter is only effective when it is encased in the same rf-tight enclosure as the ruthenium oxide sensor. Our design delivers an attenuation level that is necessary to mitigate the effects of parasitic heating of a fraction of pW present in our circuit. Furthermore, we show that the likely origin of this parasitic heating is the black body radiation present within the experimental space of the refrigerator. We found that the equilibration time of the thermometer increases rapidly as the temperature is lowered; below 5 mK this thermometer becomes impractical because of the prohibitively long equilibration times.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Development and Bench-Scale Testing of a Novel Biphasic Solvent-Enabled Absorption Process for Post-Combustion Carbon Capture (Final Technical Report)

A new class of biphasic solvents was developed, and the concept of the enabled carbon dioxide (CO 2 ) absorption process was tested for post-combustion carbon capture in our previous lab-scale research. The primary goals of this project were to advance the development of the novel biphasic CO 2 absorption process (BiCAP) and validate its technical advantages by testing the integrated technology at a 40 kWe bench-scale with actual coal-derived flue gas in a power plant environment. The project was led by the University of Illinois at Urban-Champaign (UIUC), and Trimeric Corporation served as a sub-awardee providing support in basic design and techno-economic studies. To achieve the project goals and objectives, solvent management studies, process modeling and optimization, bench-scale equipment design, construction and testing, and technical, economic and environmental assessments have been conducted. The two top-performing biphasic solvents developed in our previous research were used in this project. Biphasic solvent emissions and control were investigated in the laboratory. The emissions of the biphasic solvents from the absorber were comparable to or lower than the reference 30 wt% monoethanolamine (MEA) solution, while they could be more effectively removed in the water wash column. Lab-scale testing of solvent degradation reclamation has revealed that vacuum distillation was feasible for biphasic solvent reclamation. Aspen Plus models were used to optimize the BiCAP, and a CO 2 stripping configuration introducing a secondary cold solvent feed to the stripper was identified to be the most energy efficient. A 40 kWe bench-scale, integrated BiCAP system was successfully designed, fabricated, and installed at the UIUC’s Abbott Power Plant. Parametric testing with synthetic flue gas has demonstrated that the two biphasic solvents required a more than 40% lower heat duty for CO 2 desorption as compared to the reference MEA tested on the same bench-scale skid. Slipstream testing with actual coal flue gas for a total of 31 days in two test campaigns has further demonstrated stable operation of the bench-scale skid. During the first campaign targeting 90% CO 2 removal, the heat duty averaged at 2,183 MJ/tonne of CO 2 captured and during the second campaign targeting 95% removal, the heat duty averaged at 2,450 MJ/tonne of CO 2 captured. A techno-economic analysis has revealed that for integration of the BiCAP into a 650-MWe pulverized coal-fired power plant, the parasitic power loss was reduced by ~20%, and the cost of CO 2 capture was reduced by ~21% ($36.3/tonne on a December 2018 dollar basis) compared to the U.S. Department of Energy (DOE)’s baseline Case B12B. As progression from this bench-scale development effort, a new project “Engineering-Scale Testing of the Biphasic Solvent Based CO 2 Absorption Capture Technology at a Covanta Waste-to-Energy Facility” was awarded by the DOE, launched in February 2023, to allow the team to further test the technology and demonstrate its technical and economic advantages at a pilot scale.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Effects of midplane density gradient in the propagation of high-harmonic fast waves considering high temperature anisotropy in the scrape-off layer of NSTX-U

High-Harmonic Fast Wave (HHFW) heating experiments in NSTX have shown that up to 60% of the injected power can be lost in the Scrape-Off Layer (SOL) when the density is above the fast wave cutoff density in front of the antenna, for which the fast wave is able to propagate into the plasma. This work models HHFW propagation in the SOL plasmas of NSTX-U using a 2D divertor SOL profile derived from the pressure assumption and the finite element temperature solution, which accounts for the high anisotropy of heat conduction in a 2D axisymmetric geometry. In this work, the two-dimensional axisymmetric SOL temperature profile is first evaluated by solving the steady-state non-linear heat conduction equation, in which thermal conductivity depends on temperature, using a finite element approach in the Petra-M workbench. A 2D density profile is then obtained from a prescribed density profile at the outer midplane assuming pressure is uniform along a flux tube in the SOL. This approach results in density and temperature profiles in which the strong asymmetric nature of heat conduction between the parallel and perpendicular background magnetic field is successfully captured. Furthermore, this work focuses on investigating the effect of the SOL plasma density profile on parasitic HHFW propagation in the SOL. The simulation results show that the radial gradient of the density profile affects the wavefield propagation in the SOL. As the density profile broadens, the wavefield intensity and its poloidal extent are reduced in the SOL, and the core coupling increases. Similarly, as shown by collisional power deposition, a proxy for power absorption, the fraction of power deposited in the SOL decreases with a broadening profile.

HHFW↗
DOE OSTI2020

Probing Depth-Dependent Transition-Metal Redox of Lithium Nickel, Manganese, and Cobalt Oxides in Li-Ion Batteries

Layered lithium nickel, manganese, and cobalt oxides (NMC) are among the most promising commercial positive electrodes in the past decades. Understanding the detailed surface and bulk redox processes of Ni-rich NMC can provide useful insights into material design options to boost reversible capacity and cycle life. Both hard X-ray absorption (XAS) of metal K-edges and soft XAS of metal L-edges collected from charged LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) and LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) showed that the charge capacity up to removing ~0.7 Li/f.u. was accompanied with Ni oxidation in bulk and near the surface (up to 100 nm). Of significance to note is that nickel oxidation is primarily responsible for the charge capacity of NMC622 and 811 up to similar lithium removal (~0.7 Li/f.u.) albeit charged to different potentials, beyond which was followed by Ni reduction near the surface (up to 100 nm) due to oxygen release and electrolyte parasitic reactions. Overall, this observation points toward several new strategies to enhance reversible redox capacities of Ni-rich and/or Co-free electrodes for high-energy Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2021

Aerosol emissions from water-lean solvents for post-combustion CO 2 capture

Advanced water-lean solvents (WLS) for post-combustion CO 2 capture have been gaining interest due to their ability to reduce the parasitic penalty from energy needed for solvent regeneration. Commercial implementation of these novel CO 2 capture technologies hinges on successful control of amine emissions. RTI conducted a parametric study of fundamental and operational variables influence on overall amine aerosol and vapor emissions from our water-lean solvent eCO 2 Sol™ using our 6-kW equivalent bench-scale gas absorption system. The parametric testing used a simulated flue gas with 15 % CO 2 , 2.3–4.2 % H 2 O, and 0–6 ppm sulfite (SO 3 ) to examine the impact of the presence of aerosols to the capture performance and amine emissions from the system. The SO 3 reacts with water in the flue gas to create H 2 SO 4 , which forms liquid aerosol droplets and provide nucleation sites for growth of aerosols. Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer instruments monitored the aerosol particle size distribution. Parametric testing results suggested that the presence of the aerosols in the flue gas could increase the overall amine emissions by 10X compared to the baseline emissions from WLS’s vapor pressure. Principal component analysis (PCA) and projection to latent squares (PLS) developed models to predict the aerosol-based amine emissions from process data. The predictive PLS model had a correlation coefficient (Q 2 ) of 0.92 and could predict the aerosol-based emissions from the NAS process with ±15 % accuracy (average absolute deviation, AAD). The PLS regression model also identified key variables affecting aerosol-based emissions from WLS.

42 ENGINEERING↗
DOE OSTI2023

In situ microscopy and spectroscopy characterization of microsized Sn anode for sodium-ion batteries

Microsized Sn is a promising anode material for sodium-ion batteries in terms of cost, specific capacity, and volumetric energy density, which however suffers from huge volume changes and rapid cell degradation upon cycling. Despite recent advances via nanostructured electrode design and interface engineering, the correlation between mechanical stability, solid-electrolyte interphase (SEI) and reaction kinetics/reversibility remains controversial and elusive. Here, in this work, by combining in situ scanning electron microcopy and X-ray absorption spectroscopy as well as X-ray photoelectron spectroscopy, we have investigated the underlying electro-chemo-mechanical behavior and their coupling effects during charge/discharge of microsized Sn anode. Our results revealed that microsized Sn is pulverized into nanoparticles with simultaneous formation of numerous voids and pores upon the 1st charge/discharge, while the electrolytes composition plays a critical role on the consequent parasitic reactions and eventually the sodiation/de-sodiation reversibility. In contrast to carbonate-based electrolytes, ether-based electrolytes enabled formation of inorganic species dominated SEI with improved mechanical strength, thus leading to higher specific capacity and improved cycling stability. The present findings are crucial for future development of microsized anode materials for rechargeable batteries with high volumetric energy density.

25 ENERGY STORAGE↗
DOE OSTI2025

Electrochemical Reduction Pathways from Goethite to Green Iron in Alkaline Solution with Silicate Additive

Energy-efficient and low-temperature iron electrolysis in alkaline solutions is a low-cost and sustainable ironmaking process with zero-carbon emissions when renewable electrical sources are involved. However, its implementation is hindered by electrochemically inert Fe 3 O 4 and parasitic H 2 gas formation during the electrochemical reduction process, resulting in the low energy efficiency of iron electrolysis. Here, we further explore the potential of electrochemical reduction of goethite (FeOOH) by employing a low concentration of silicate additive in an alkaline solution to mitigate Fe 3 O 4 accumulation and H 2 generation. Electrochemical measurements coupled with operando X-ray diffraction and X-ray absorption spectroscopy suggested FeOOH → Fe 3 O 4 → Fe(OH) 2 → Fe reduction pathways. Interestingly, a poorly crystalline or amorphous Fe(OH) 2 phase formed in the NaOH/silicate mixed electrolyte, possibly due to the inhibitive effect of silicate on water and ion transport, which eventually contributed to the improved reduction of Fe 3 O 4 , also supported by atomistic simulations. This work demonstrates the potential for silicate as a low-cost and effective electrolyte additive to improve room-temperature green iron formation via electrolysis.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The role of Li doping in layered/layered Na x Li y Ni 0.4 Fe 0.2 Mn 0.4 O 2 intergrowth electrodes for sodium ion batteries

Here, the layered NaTMO 2 (TM = Ni, Fe, Mn) materials with the O3-type structure are attractive as positive electrodes for sodium ion batteries because of their high theoretical capacity. Additionally, Li doping in these materials has been shown to offer substantial enhancements to their electrochemical properties by promoting the formation of intergrowth structures, which are combinations of specific phases. However, the mechanism by which the intergrowth modifies the electrochemical properties is often unclear. Systematic variation of Li content in Na x Li y Ni 0.4 Fe 0.2 Mn 0.4 O 2 (NFM-Li y ) was conducted to identify its role in structural modification and electrochemical performance. Li contents of 0.15 and greater generate a layered/layered Na-O3/Li-O’3 intergrowth structure. 7 Li and 23 Na nuclear magnetic resonance and x-ray absorption spectroscopy identify that when the total solubility for alkali ions in the layered structure is exceeded, Li continues to form the Li-O’3 phase while the excess Na forms residual sodium compounds such as Na 2 O. Higher Li content is associated with improved capacity retention in the initial cycles from the superior stability of the mechanically linked NaO3/Li-O’3 structure that suppresses the P3 to OP2 phase transition during charge. However, high Li contents are associated with increased rates of parasitic side reactions that reduce long-term cycling stability. These side reactions are associated with the instability of the cathode-electrolyte interphase, which can be partially mitigated by atomic layer deposition (ALD) coating with alumina, which significantly enhances the capacity retention and Coulombic efficiency over many cycles. Overall, we find that the layered/layered Na-O3/Li-O’3 intergrowth structure is able to provide structural stability and suppress undesired phase transformations but is overwhelmed by the increased reactivity of the surface if not protected by surface coating.

25 ENERGY STORAGE↗
DOE OSTI2021

Investigations of LHW-plasma coupling and current drive at high density related to H-mode experiments in EAST

Two important issues in achieving lower hybrid current drive (LHCD) high confinement plasma in EAST are to improve lower hybrid wave (LHW)-plasma coupling and to drive the plasma current at a high density. Studies in different configurations with different directions of toroidal magnetic field (Bt) show that the density near the antenna is affected by both the radial electric field induced by plasma without a LHW (Er-plasma) in the scrape off layer (SOL), and the radial electric field induced by LHW power (Er-LH) near the grill. Investigations indicate that Er× Btin the SOL leads to a different effect of configuration on the LHW-plasma coupling and Er-LH× Btaccounts for the asymmetric density behaviour in the SOL observed in the experiments, where Eris the total radial electric field in the SOL. Modelling of parametric instability (PI), collisional absorption (CA) and scattering from density fluctuations (SDF) in the edge region, performed considering the parameters of high density LHCD experiments in EAST, has shown that these mechanisms could be responsible for the low current drive (CD) efficiency at high density. Radiofrequency probe spectra, useful for documenting PI occurrence, show sidebands whose amplitude in the case of the lithiated vacuum chamber is smaller than in the case of poor lithiation, consistently with growth rates from PI modeling of the respective reference discharges. Since strong lithiation is also expected to diminish the parasitic effect on the LHCD of the remaining possible mechanisms, this appears to be a useful method for improving LHCD efficiency at a high density.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

A Process with Decoupled Absorber Kinetics and Solvent Regeneration through Membrane Dewatering and In-Column Heat Transfer (Final Report)

This report summarizes the work conducted on project DE-FE0031604 where University of Kentucky Center for Applied Energy (UK CAER) has validated its intensified CO 2 capture process through substantial enhancements to the kinetics of the absorption process and energy reductions by absorber temperature profile modification, dewatering and heat integration technologies for achieving significant capital and operating cost reductions. To address DOE’s objective of improving post-combustion CO 2 capture technology and reducing associated cost, UK CAER employed an intensified process which combined three key aspects targeted at overcoming inherent limitations or barriers in the conventional CO 2 capture and desorption process. The process designed to be independent of the type of solvent used, included (1) the use of 3-D printed two-channel structured packing material to control the temperature profile and increase the CO 2 absorption rate in the absorber, (2) a zeolite membrane dewatering unit for dewatering of the carbon-rich solvent to decouple solvent concentration needs for CO 2 absorption and desorption, and (3) a rich-split feed with two-phase flow heat transfer prior to the stripper that provided a secondary point of vapor generation to provide energy savings in steam extraction and solvent regeneration. The project was executed over two budget periods. This involved testing of individual process components which included the advanced heat transfer packing and the dewatering membrane on UK CAER’s 30 liter per minute (L/min) CO 2 (3” Column) capture bench unit with simulated flue gas in the first budget period. Subsequent scaled-up testing of these components together with the split-feed configuration were also tested in UK CAER’s 0.1 MWth CO 2 capture unit with coal-derived flue gas in the second-budget period. Long term studies were done during this period to assess process and solvent performance over extended duration. Project partners Lawrence Livermore National Laboratory (LLNL) and Media & Process Technology (MPT) led the development efforts for the advanced packing material and dewatering membrane respectively. Data from the long term testing was used as input for an environmental, health and safety (EH&S) assessment for the process and scaled technology performed by ALL4 LLC. Trimeric Corporation also completed a techno-economic analysis (TEA) for the UK CAER technology which was compared to the DOE reference Case B12B. Tests on the 3” column capture unit showed that the advanced heat transfer packing could be used to lower the bulge temperature in the absorber, and this was also proven in the scaled testing in the 0.1 MWth CO 2 capture unit. The bulge temperature could be lowered by >10 °C, changing the temperature profile in the absorber, and showed potential to enhance absorption with the ability to tailor the profile to provide conditions suitable for a solvent’s properties and kinetics. Conditions for short term evaluation of a 19” zeolite dewatering membrane on the 3” column capture unit yielded desirable fluxes and sustained rejection rates of >80%. However, for the scaled testing of six membrane modules consisting of 21 parts of 31-inch-long membrane tubes in each bundle (surface area 0.3 m 2 ), over a more extended duration, similar rejection rates could not be achieved. With the split-feed of the rich stream to the stripper, improved heat recovery minimized waste heat exiting the top of the stripper. The stripper exhaust temperatures could be reduced by >10 °C; reducing the amount of water vaporization contributed to lowering the regeneration energy by ~ 15%. The energy benefit could be sustained from the long term monitoring of the solvent performance. The solvent properties were not significantly impacted over the long-term operations. The benefits of the UK CAER process demonstrated experimentally were mostly validated from the TEA comparing a commercial scale application of the technology to DOE reference Case B12B. The cost of CO 2 capture for the UK CAER technology was estimated to be ~$34.97/tonne of CO 2 captured; a reduction of 23% compared to Case B12B. The increase in cost of electricity was also shown to be 16% lower than that of Case B12B. The total parasitic demand was also shown to be 11% lower. The key drivers for the benefits are a result of the process intensification approaches employed in the UK CAER technology for enhanced solvent performance, effective heat recovery and improved energy performance. The EH&S assessment did not find any major environmental concerns or barriers to the full scale implementation of the technology.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2020

Application of a Heat Integrated Post-combustion CO 2 Capture System with Hitachi Advanced Solvent into Existing Coal-Fired Power Plant (Final Technical Report)

The goal of this final project report is to comprehensively summarize the work conducted on project DE-FE0007395. In accordance with the Project Management Plan (PMP), Revision F dated 5/10/2019, and Statement of Project Objectives (SOPO) within, the University of Kentucky (UK) Center for Applied Energy Research (CAER) (Recipient) has successfully demonstrated a unique, versatile CO 2 capture system (CCS) using a heat integrated process combined with two-stage stripping for process intensification, heat recovery and demineralized (DM) water generation. This project involved the design, fabrication, installation, testing of and data analysis from the UK CAER 0.7 MWe small pilot scale CO2 capture process installed at Kentucky Utilities (KU) E.W. Brown Generating Station in Harrodsburg, KY. During each of the four project Budget Periods (BPs), UK CAER met all project deliverables, all project milestones, with National Energy Technology Laboratory (NETL) approved adjustments made to the campaign long-term hours during BP4. The CCS was constructed in modular skids. Two solvent campaigns were initially conducted; the first with a 30 wt% monoethanolamine (MEA) as a baseline, and the second with the Hitachi H3-1 advanced solvent. Additional tests were performed with two advanced solvents including CAER and Proprietary Solvent C. Short-period testing with a higher concentration of 40 wt% MEA was conducted to evaluate the potential saving with high alkalinity. From the various solvent campaigns, unique aspects of the UK CAER CCS technology, as well as its flexibility and versatility were experimentally validated and demonstrated. With respect to solvent evaluation efforts in identifying candidates with significant operational and capital cost savings potential, performance of solvents were evaluated to determine the energy requirements for regeneration; environmental impacts from secondary emissions and degradation products; degradation rates, solvent make-up rates and stability. The assessments were done from parametric tests that determined optimum operating conditions for the individual solvents to maximize process efficiency and minimize the parasitic load of the power plant, and from long term campaigns (1000 hours for 30 wt% MEA and 1000 hours for H3-1) which collectively informed the techno-economic analyses (TEA) of the process. The long term campaigns included corrosion studies which used three types of metal coupons in different sections of the process: (absorber, primary stripper, lean carbon-loaded and rich carbon loaded flow streams in process) to mimic heat and flow dynamics process equipment were exposed to. The estimated corrosion rates were used to elucidate corrosion mechanisms and to further guide process material selection for potential capital cost savings.

gas separation↗
DOE OSTI2025

Investigation of electrode-electrolyte interfaces to enable non-flammable Li-ion batteries operating up to 125°C with liquid electrolyte

Non-flammable and high-temperature stable ionic liquid (IL)-based electrolytes could eliminate catastrophic battery failures and improve battery safety, but their poor electrochemical interaction with the LiNi x Mn y Co z O 2 (NMC) family of cathodes is a long-standing problem due to severe parasitic reactions at high temperature. Understanding surface and bulk structural mechanisms of NMC-type cathodes at elevated operational temperature is of paramount importance to facilitate stable electrochemical performance. Here, we report a non-flammable phosphonium IL-based cell chemistry that offers stable electrode-electrolyte interfaces, leading to electrochemical performance up to 125°C and high-temperature safety. We combine electrochemistry with multimodal X-ray spectroscopy methods to understand interfaces at elevated temperature (100°C). This nanoscale understating enables a proof-of-concept high-temperature cylindrical cell (14500), and the design achieves an average Coulombic efficiency of ≈99.5% up to 300 cycles at 100°C. The results ascertain the significance of depth-dependent degradation at the interface, guiding room-temperature Li-ion technology toward extreme-temperature applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Structure-Based Discovery and Development of Highly Potent Dihydroorotate Dehydrogenase Inhibitors for Malaria Chemoprevention

Malaria remains a serious global health challenge, yet treatment and control programs are threatened by drug resistance. Dihydroorotate dehydrogenase (DHODH) was clinically validated as a target for treatment and prevention of malaria through human studies with DSM265, but currently no drugs against this target are in clinical use. We used structure-based computational tools including free energy perturbation (FEP+) to discover highly ligand efficient, potent, and selective pyrazolebased Plasmodium DHODH inhibitors through a scaffold hop from a pyrrole-based series. Optimized pyrazole-based compounds were identified with low nM-to-pM Plasmodium falciparum cell potency and oral activity in a humanized SCID mouse malaria infection model. The lead compound DSM1465 is more potent and has improved absorption, distribution, metabolism and excretion/pharmacokinetic (ADME/PK) properties compared to DSM265 that support the potential for once-monthly chemoprevention at a low dose. This compound meets the objective of identifying compounds with potential to be used for monthly chemoprevention in Africa to support malaria elimination efforts.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Emissions mitigation technology for advanced water-lean solvent-based CO 2 capture processes

This technical final report submitted to DOE/NETL presents all the research activities performed during the entirety of DE-FE0031660 project-Emissions Mitigation Technology for Advanced Water-Lean Solvent-Based CO 2 Capture Processes which spans from October 2018 through March 2022. RTI International has been conducting studies from fundamental and operational aspects to reduce the overall amine emissions from the advanced Water-Lean Solvent (WLS) systems, specifically RTI’s Non-Aqueous Solvent (NAS). This technical final report will highlight the key findings from project which align closely to the project objectives which are: Identify the contribution of vapor loss, entrainment, and aerosols to the overall emissions of water-lean systems; Determine the significance of CO 2 capture system operating parameters to the amine emissions; Develop an emissions model based on critical operating parameters; Evaluate the effectiveness of emissions mitigation devices to reduce the amine emissions to <1 ppm under flue coal-fired flue gas; and, Determine the contribution of the ECTs to the overall CO 2 capture cost. The following are the key findings based on numerous tests using both lab-scale setups and parametric testing performed at RTI’s Bench-scale Gas Absorption System (BsGAS). During the BP1, the aerosol generation system and monitoring equipment were installed at BsGAS to produce and determine the aerosol characteristics during the NAS CO 2 capture process. The aerosol produced by this setup produced aerosols with the peak diameter and concentration of 50 micron and 1.2E10 7 cm -3 , respectively. These particle sizes and concentrations are matched to those observed in the actual coal-fired power plant flue gases and expected to be found at the absorber inlet of the CO 2 capture system. Over 1,300 hours of parametric testing have been conducted to evaluate the impact of the aerosols and operating conditions during the CO 2 capture with NAS on the overall amine emissions in the treated flue gas. At the worse condition tested, the presence of the aerosols in the flue gas could increase the overall emissions by 10X compared to the baseline emissions from NAS’s vapor pressure. CO 2 capture rate was found to be a main factor impacting the overall emissions as well as aerosol size and concentrations in the absorber off-gas. The higher CO 2 capture rate, the higher amine emissions in the treated gas. The temperature difference between the temperature bulge seen in the absorber and the water wash temperature also impacts the particle growth where the larger the temperature difference, the more amine emissions from aerosols in the treated gas. The majority of the aerosols did not grow substantially in the system, and the particle concentrations remained nearly constant between the absorber inlet and wash outlet. Only a small portion of the particles were found to grow significantly. The high efficiency demister with mesh size of 5-10 micron can be installed to remove a portion of the aerosols from the gas stream leaving the water wash. Overall, these results from parametric testing have established the emission baseline and validate our assumption on the need of emission control technologies (ECT) in order to minimize the emissions from the baseline NAS CO 2 capture process. Over 2,000 of BsGAS operating hours was used to investigate a handful of process improvements which led to a selection of the vital few changes that effectively control the amine emissions. These process improvements are lime-coated-filters for absorber gas inlet, advanced demister at the top of the absorber, a second water wash with amine recovery unit were designed, installed, and tested at BsGAS at the end of BP1. The result showed that the NAS CO 2 capture process with these additional emission control devices could lower the amine emission in the treated gas to about 1 ppm using a simulated coal-fire flue gas stream. The main contributor in lowering the amine emission came from the second water wash with amine recovery unit where the amine concentration in the scrubbing water was kept below 2 wt% through a continuous amine removal via an adsorbent bed, resulting in a low amine vapor pressure. The adsorbent bed was regenerated via a direct steam regeneration and the recover amine was returned to the absorber to minimize wastewater and makeup amine. A flue gas generation system was designed and installed during the first half of BP2 to support the emission testing using a real coal-derived flue gas. The system is capable of generating both coal- and natural gas- derived flue gases with the composition of the gaseous species highly resemble to that of the power plant flue gases. The particulates detected in the coal-derived flue gas showed the mean diameter of 1 micron. The CO 2 capture operating was then proceed using the real coal-derived flue gas where the amine emission was controlled to be about 0-3 ppm for the total run time of about 200 hours. Similar testing was conducted with natural gas-derived flue gas and the result showed a highly amine emission of 30 ppm under the total run time of 200 hours. The Principal Component Analysis (PCA) and the Partial Least Squares Projection to Latent Structures (PLS) techniques were applied to the parametric testing data to derive a multivariate statistical model. The model was validated and trained with half of the data collected, and the predictive ability of the model was evaluated using the remaining half of the data. The resulting empirical model was capable of predicting the overall emissions from the NAS process without the ECTs with ±15% accuracy (average absolute deviation, AAD) in BP1. As more emission data were obtained under the real coal-flue gas in the BP2, the model incorporated these new set of data to reflect the final process configuration, operating parameters, and amine emission. This results in the updated empirical model predicting the amine emission from the NAS CO 2 capture process with 84% goodness-of-fit (R 2 ), 85% predictability (Q 2 ), and 15% AAD. The study evaluates the use of RTI’s Non-Aqueous Solvent technology for 90% CO 2 capture from a net 650 MWe pulverized coal power plant, downstream of the flue-gas desulfurization unit. The captured CO 2 has a purity of > 95% CO 2 , and is dried, compressed to 15.3 MPa (2,215 psia), ready for sequestration. The analysis uses Case B12B from the DOE Baseline study on Bituminous Coal, Revision 4 where the Cansolv CO 2 capture plant is replaced by the RTI CO 2 Capture plant. The CO 2 capture plant has been sized to capture >90% CO 2 from flue gas derived from a net 650 MWe supercritical pulverized coal power plant. The CO 2 capture plant is equipped with emission control technologies that limits the amine emissions to < 1 ppm. Two different cases were evaluated for the technoeconomic study. The key difference between the two cases is the regenerator pressure. In Case 1, the regenerator operates at 0.195 MPa (28.3 psia), whereas in Case 2, the regenerator pressure is 0.44 MPa (64 psia) thus removing the need for the first stage of compression of the eight-stage compression train. Results from the TEA are compared against the DOE reference cases for SCPC plant with and without CO 2 Capture (Case B12A and Case B12B of the DOE Baseline study, respectively). Case 2 with CO 2 regeneration at higher pressure results in the lower cost of CO 2 capture. The total capital cost of the capture process has been estimated using 2018 dollars in Aspen Process Economic Analyzer and was estimated to be $579 MM. The capture plant operation leads to a total parasitic power loss rate of 96 MWe, resulting in a decrease in pulverized coal power plant efficiency of 7.8% points. The resulting cost of electric power increases from 64.4 mills/kWh, for no capture, to 97.5 mills/kWh, with 90% capture, an increase of 51% in the COE. The cost of capturing 90% CO 2 was estimated to be $38.2/tonne-CO 2 , and meets the DOE target of $40/t-CO 2 . Emission control technologies (ECT) investigated in this project includes a second water wash with use of activated carbon beds for removal of amine from the wash water prior to recirculation in the water wash. These ECT allow operation of the CO 2 capture plant with < 1 ppm amine emissions with the treated flue gas and contributes to $2.4/t-CO 2 captured. Amine emissions derived from thermal and oxidative degradations were investigated under this project along with the emissions derived from aerosols for the NAS system. The thermally degraded of the lean NAS showed less than 4% decreased of the original total amine content in the NAS at 150 °C while the result obtained at 120 °C showed no drop in total amine content, suggesting that thermal degradation of the NAS is minimal. These results also suggested that the thermally degraded species are not likely formed and contributed to the emissions due to the low regeneration temperature of the NAS at 90-105 °C. The oxidative degradation, on the other hand, could become problematic as some of these oxidative degraded species were observed during the NAS-5 testing at National Carbon Capture Center (NCCC) and SINTEF in our previous project. The rapid screening of selected inhibitors suggested that oxidative degradation of NAS can be suppressed using thiol containing compounds in amounts of at least 1 mol%. The detailed mechanistic degradation pathway was conceived for a specific amine used in NAS formulation during BP2. he reduction of the nitrosamines caused by the NO x present in the flue gas was also examined. The study suggested that the thermo-chemical treatment of the NAS solvent would be a more effective and economically viable compared to removing NO x at the DCC.

01 COAL, LIGNITE, AND PEAT↗