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At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

DOE OSTI2021

Toward sustainable, cell-free biomanufacturing

Industrial biotechnology is an attractive approach to address the need for low-cost fuels and products from sustainable resources. Unfortunately, cells impose inherent limitations on the effective synthesis and release of target products. One key constraint is that cellular survival objectives often work against the production objectives of biochemical engineers. Additionally, industrial strains release CO2 and struggle to utilize sustainable, potentially profitable feedstocks. Cell-free biotechnology, which uses biological machinery harvested from cells, can address these challenges with advantages including: (i) shorter development times, (ii) higher volumetric production rates, and (iii) tolerance to otherwise toxic molecules. In this review, we highlight recent advances in cell-free technologies toward the production of non-protein products beyond lab-scale demonstrations and describe guiding principles for designing cell-free systems. Specifically, we discuss carbon and energy sources, reaction homeostasis, and scale-up. Expanding the scope of cell-free biomanufacturing practice could enable innovative approaches for the industrial production of green chemicals.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Understanding Recoverable vs Unrecoverable Voltage Losses and Long-Term Degradation Mechanisms in Anion Exchange Membrane Fuel Cells

Anion exchange membrane fuel cells (AEMFCs) have recently shown excellent progress in terms of their performance – e.g., achievable power and current density. However, very few AEMFCs have been demonstrated with the ability to operate for a long duration (>1000 h). In addition, it is unknown whether performance losses observed during operation are reversible, irreversible, or a combination of the two. In this study, a high-performance AEMFC operated continuously at 600 mA/cm 2 for 3600 h (150 days) at 80 °C with H 2 /O 2 reacting gases was demonstrated. Throughout testing, the electrochemical properties of the AEMFC were probed to provide information about performance degradation pathways and their degree of reversibility. It was found that a portion of the performance loss that occurs during AEMFC operation was due to suboptimal reaction conditions and can be recovered. At the end of the experiment, the cell was disassembled, and its structure and composition were evaluated at the nanoscale by aberration-corrected scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. The structure and composition of the electrode were compared to cells at the beginning of their operational life. It was found that the primary mechanism for long-term AEMFC performance loss was catalyst agglomeration. During the operational time, there was no evidence of significant polymer degradation, likely due to the high hydration state of the cell. By documenting the long-term changes in high-performing AEMFCs, this work provides important information for the systematic design of cell components and demonstrates the importance of controlling cell operation, which can aid in the commercialization and widespread deployment of low-cost, long-life AEMFCs.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2023

Characterization of Interconnects

Combined-accelerated stress testing (C-AST) simultaneously combines stress factors of the natural environment (including UV radiation, temperature, humidity, electrical current, and external mechanical force) into a single test that requires fewer modules, fewer chambers, and makes it possible to discover weaknesses in new designs that are not known a-priori. C-AST reduces risk, accelerates time to market, and improves bankability by reducing costly overdesign using test levels not exceeding those seen in the natural environment. This project seeks to evaluate strengths and weaknesses of modern cell interconnect designs with combined-accelerated stress testing (C-AST) to screen multiple climates along with finite element and failure analysis to determine the potential for a 50-year life. Supporting this, we seek to develop methods of characterization to assess the degradation of interconnects, enable predictive rate models with material forensics and FEA and show C-AST's ability to find interconnect failures and benchmark it relative to other accelerated stress test methods like temperature cycling and cyclic dynamic mechanical loading. Examples of modern interconnect designs covered are Canadian Solar Hetero Technology ribbon enabling closer cell interconnections, SmartWire (eg. Meyer-Berger technology), and shingled cells with new interconnect materials.

C-AST↗

DOE OSTI2021

Beam Stability Overview [Slides]

Radiographic spot size is affected by many factors, including beam motion due to instabilities. Instabilities and effects that can influence the radiation-source spot size are being evaluated for the Scorpius flash-radiography accelerator. The Scorpius LIA design has a direct influence on beam stability. Many features of the design were specifically incorporated to mitigate instability. The major beam dynamics concerns for high-current LIAs are being evaluated for the long, 102-cell Scorpius design. For these results, all tools available were used including experimental data, analytic theory, and physics simulation codes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2023

Protonic Ceramic Electrochemical Cells for Synthesizing Sustainable Chemicals and Fuels

Abstract Protonic ceramic electrochemical cells (PCECs) have been intensively studied as the technology that can be employed for power generation, energy storage, and sustainable chemical synthesis. Recently, there have been substantial advances in electrolyte and electrode materials for improving the performance of protonic ceramic fuel cells and protonic ceramic electrolyzers. However, the electrocatalytic materials development for synthesizing chemicals in PCECs has gained less attention, and there is a lack of systematic and fundamental understanding of the PCEC reactor design, reaction mechanisms, and electrode materials. This review comprehensively summarizes and critically evaluates the most up‐to‐date progress in employing PCECs to synthesize a wide range of chemicals, including ammonia, carbon monoxide, methane, light olefins, and aromatics. Factors that impact the conversion, selectivity, product yield, and energy efficiencies are discussed to provide new insights into designing electrochemical cells, developing electrode materials, and achieving economically viable chemical synthesis. The primary challenges associated with producing chemicals in PCECs are highlighted. Approaches to tackle these challenges are then offered, with a particular focus on deliberately designing electrode materials, aiming to achieve practically valuable product yield and energy efficiency. Finally, perspectives on the future development of PCECs for synthesizing sustainable chemicals are provided.

03 NATURAL GAS↗

DOE OSTI2020

Understanding and applying coulombic efficiency in lithium metal batteries

Coulombic Efficiency (CE) has been widely used in battery research as a quantifiable monitor to compare the properties and performances of materials, electrolytes, interfaces and the entire electrochemical cells. While CE with ultra high precision effectively predicts the lifespan and health for lithium ion (Li-ion) batteries, it is not necessarily true in rechargeable lithium (Li) metal batteries. A large variation of CE is often seen even from the same materials and electrolytes in Li metal cells. This work discusses the fundamental definition of CE in different configurations of Li metal-based cells. The similarities and differences of CE in Li-ion and Li metal cells have been clarified and used to understand the relevance/irrelevance between CE and cycling. Long-standing goal of this study is to help rational design of cell testing protocols and elaborate electrochemical results. The insights from this work are broadly applicable in many other rechargeable metal cells e.g., Zn, Mg and Na batteries to accelerate reseach innovation.

Xiao, Jie↗

DOE OSTI2021

Rational design of platinum-group-metal-free electrocatalysts for oxygen reduction reaction

Platinum-group-metal (PGM)-free materials have been promised as potential replacement for Pt as the cathodic catalyst in proton exchange membrane fuel cells. Critical design criteria of the PGM-free catalyst reside on the high active site density to compensate its generally lower turn-over frequency and improved mass-charge transfers during the electrocatalysis. Herein, this short review summarizes the research activities in recent years from our team at Argonne National Laboratory in preparing highly active oxygen reduction reaction (ORR) catalysts using rationally designed porous organic precursors, as reported in the First Telluride Science Research Center (TSRC) Workshop on PGM-free Electrocatalysis in 2019. More recent studies by others are also discussed.

25 ENERGY STORAGE↗

DOE OSTI2022

Environmental cell for in situ X-ray synchrotron micro-CT imaging with simultaneous acoustic measurements

Synchrotron radiation provides the necessary spatial and temporal resolution for non-invasive operando studies of dynamic processes under complex environmental conditions. Here a new environmental cell for simultaneous in situ dynamic X-ray imaging and measuring acoustic properties of geological samples is presented. The primary purpose of this cell is to study gas-hydrate formation in porous geo-materials and its influence on their acoustic properties. The cell is designed for cylindrical samples of 9 mm in diameter, confining and pore pressures up to 12 MPa, and temperatures from –20°C to room temperature. The cell is portable and can be easily assembled and operated at different X-ray sources. This cell enables a wide range of experiments studying physical/chemical processes in the Earth subsurface that change the mechanical properties of rocks (geochemical reactions, phase transitions, etc.).

47 OTHER INSTRUMENTATION↗

DOE OSTI2021

Cellular fluidics

The natural world provides many examples of multiphase transport and reaction processes that have been optimized by evolution. These phenomena take place at multiple length and time scales and typically include gas–liquid–solid interfaces and capillary phenomena in porous media. Many biological and living systems have evolved to optimize fluidic transport. However, living things are exceptionally complex and very difficult to replicate, and human-made microfluidic devices (which are typically planar and enclosed) are highly limited for multiphase process engineering. In this paper, we introduce the concept of cellular fluidics: a platform of unit-cell-based, three-dimensional structures—enabled by emerging 3D printing methods—for the deterministic control of multiphase flow, transport and reaction processes. We show that flow in these structures can be ‘programmed’ through architected design of cell type, size and relative density. We demonstrate gas–liquid transport processes such as transpiration and absorption, using evaporative cooling and CO 2 capture as examples. We design and demonstrate preferential liquid and gas transport pathways in three-dimensional cellular fluidic devices with capillary-driven and actively pumped liquid flow, and present examples of selective metallization of pre-programmed patterns. Our results show that the design and fabrication of architected cellular materials, coupled with analytical and numerical predictions of steady-state and dynamic behaviour of multiphase interfaces, provide deterministic control of fluidic transport in three dimensions. Cellular fluidics may transform the design space for spatial and temporal control of multiphase transport and reaction processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Impact of Salt Chemistry and Interlayer Architecture on Solid Electrolyte Interphase Composition and Performance

Reversible lithium metal anodes require interphases that are chemically stable, mechanically robust, and compatible with scalable processing. Here, we use slot-die-coated, salt-rich PEO interlayers to design SEI nanolayers on Cu current collectors and isolate how salt anion chemistry controls interphase composition and lithium plating/stripping behavior in architectures relevant to Li plating and anode-free cells. Mesoscale modeling shows that dendrite initiation at SEI defects is governed by a tradeoff among interphase thickness, ionic conductivity, and stiffness through defect-driven current focusing, motivating controlled formation from thin precursor layers. Using UHV-transferred XPS and ToF-SIMS depth profiling after controlled Li deposition, we find that fluorinated sulfonylimide salts (LiTFSI, LiFSI) form mixed inorganic/organic interphases containing LiF and PEO-derived alkoxides, with LiFSI producing a more LiF-dominant Li-facing surface than LiTFSI under identical conditions. In contrast, LiNO 3 -containing interlayers yield a comparatively thick nitrate-derived interphase that reduces upon Li contact to an N-rich inorganic layer (Li–N/N 3− , LiN x O y ). In Cu| |Li cells, these designed interlayers reduce interfacial resistance and improve Coulombic efficiency (CE) and critical current density (CCD) relative to uncoated controls, with LiFSI- and LiNO 3 -based interlayers providing the highest CE/CCD. Overall, the results demonstrate a manufacturing-relevant approach to engineer SEI nanolayers by salt chemistry, providing pathways to improve reversible lithium metal anodes while reducing reliance on LiTFSI.

anion chemistry↗

DOE OSTI2021

Exploring wave propagation in heterogeneous metastructures using the relaxed micromorphic model

Metamaterials are artificial structures that can manipulate and control sound waves in ways not possible with conventional materials. While much effort has been undertaken to widen the bandgaps produced by these materials through design of heterogeneities within unit cells, comparatively little work has considered the effect of engineering heterogeneities at the structural scale by combining different types of unit cells. In this paper, we use the relaxed micromorphic model to study wave propagation in heterogeneous metastructures composed of different unit cells. We first establish the efficacy of the relaxed micromorphic model for capturing the salient characteristics of dispersive wave propagation through comparisons with direct numerical simulations for two classes of metamaterial unit cells: namely phononic crystals and locally resonant metamaterials. We then use this model to demonstrate how spatially arranging multiple unit cells into metastructures can lead to tailored and unique properties such as spatially-dependent broadband wave attenuation, rainbow trapping, and pulse shaping. In the case of the broadband wave attenuation application, we show that by building layered metastructures from different metamaterial unit cells, we can slow down or stop wave packets in an enlarged frequency range, while letting other frequencies through. In the case of the rainbow-trapping application, we show that spatial arrangements of different unit cells can be designed to progressively slow down and eventually stop waves with different frequencies at different spatial locations. Finally, in the case of the pulse-shaping application, our results show that heterogeneous metastructures can be designed to tailor the spatial profile of a propagating wave packet. Collectively, these results show the versatility of the relaxed micromorphic model for effectively and accurately simulating wave propagation in heterogeneous metastructures, and how this model can be used to design heterogeneous metastructures with tailored wave propagation functionalities.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2022

Leakless end-to-end transport of small molecules through micron-length DNA nanochannels

Designed and engineered protein and DNA nanopores can be used to sense and characterize single molecules and control transmembrane transport of molecular species. However, designed biomolecular pores are less than 100 nm in length and are used primarily for transport across lipid membranes. Nanochannels that span longer distances could be used as conduits for molecules between nonadjacent compartments or cells. We design micrometer-long, 7-nm-diameter DNA nanochannels that small molecules can traverse according to the laws of continuum diffusion. Binding DNA origami caps to channel ends eliminates transport and demonstrates that molecules diffuse from one channel end to the other rather than permeating through channel walls. These micrometer-length nanochannels can also grow, form interconnects, and interface with living cells. This work thus shows how to construct multifunctional, dynamic agents that control molecular transport, opening ways of studying intercellular signaling and modulating molecular transport between synthetic and living cells.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2021

Pressure-Induced Enhancement of Thermoelectric Figure of Merit and Structural Phase Transition in TiNiSn

Half-Heusler thermoelectric materials are potential candidates for high thermoelectric efficiency. Here, we report high-pressure thermoelectric and structural property measurements, density functional theory calculations on the half-Heusler material TiNiSn, and an increase of 15% in the relative dimensionless figure of merit, ZT, around 3 GPa. Thermal and electrical properties were measured utilizing a specialized sample cell assembly designed for the Paris–Edinburgh large-volume press to a maximum pressure of 3.5 GPa. High-pressure structural measurements performed up to 50 GPa in a diamond-anvil cell indicated the emergence of a new high-pressure phase around 20 GPa. A first-principles structure search performed using an ab initio random structure search approach identified the high-pressure phase as an orthorhombic type, in good agreement with the experimental results.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Design and characterization of “flow-cell” integrated-flow active cooling for high-average-power ceramic optics

We used COMSOL Multiphysics to design a prototype actively cooled “flow-cell” substrate targeted at high-average-power applications, fabricated the prototype from cordierite ceramic, and tested the substrate under load in our thermal loading test stand. Sub-aperture testing revealed average-power handling up to 3.88-W/cm 2 absorbed power density, in excellent agreement with model predictions. Gratings fabricated on 2-in.-diam cordierite coupons were subjected to laser-damage testing and showed a damage threshold of 250 mJ/cm 2 .

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Pure-Water-Fed Forward-Bias Bipolar Membrane CO 2 Electrolyzer

Coupling renewable electricity to reduce carbon dioxide (CO 2 ) electrochemically into carbon feedstocks offers a promising pathway to produce chemical fuels sustainably. While there has been success in developing materials and theory for CO 2 reduction, the widespread deployment of CO 2 electrolyzers has been hindered by challenges in the reactor design and operational stability due to CO 2 crossover and (bi)carbonate salt precipitation. Herein, we design asymmetrical bipolar membranes assembled into a zero-gap CO 2 electrolyzer fed with pure water, solving both challenges. By investigating and optimizing the anion-exchangelayer thickness, cathode differential pressure, and cell temperature, the forward-bias bipolar membrane CO 2 electrolyzer achieves a CO faradic efficiency over 80% with a partial current density over 200 mA cm –2 at less than 3.0 V with negligible CO 2 crossover. In addition, this electrolyzer achieves 0.61 and 2.1 mV h –1 decay rates at 150 and 300 mA cm –2 for 200 and 100 h, respectively. Postmortem analysis indicates that the deterioration of catalyst/polymer– electrolyte interfaces resulted from catalyst structural change, and ionomer degradation at reductive potential shows the decay mechanism. Furthermore, all these results point to the future research direction and show a promising pathway to deploy CO 2 electrolyzers at scale for industrial applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Graded Buffer Bragg Reflectors with High Reflectivity and Transparency for Metamorphic Optoelectronics

A graded buffer Bragg reflector (GBBR) is a bifunctional device component that provides the reflection of a distributed Bragg reflector and the adjustable lattice constant of a compositionally graded buffer. Prior work showed that these properties can be combined with low threading dislocation density and high reflectivity. Here, we design and demonstrate complex GBBRs for specific metamorphic solar cell applications. We design buffers that provide (1) high reflectivity over a narrow bandwidth, for quantum well solar cells, (2) reflectivity over a wide bandwidth, for optically thin solar cells, and (3) low sidelobe reflection, for multijunction devices that demand low out-of-band reflection. Apodized and triple GBBRs are demonstrated, and transparency is always considered, requiring designs with carefully engineered material combinations. A GBBR with a reflection of 99% is demonstrated, as well as a triple GBBR that has over 80% reflection for 100?nm of the spectrum around 800?nm. We also analyze potential deviations in a baseline GBBR from that of a perfect DBR using transmission electron microscopy to analyze imperfections in the material and modeling to analyze the impact of imperfect refractive index data for lattice-mismatched AlGaInAs. Minimal crosshatch roughness and unintentional thickness variation occur throughout the buffer, which likely influences reflection slightly. Small deviations between the calculated AlGaInAs and utilized AlGaAs refractive index exist, giving methods for future GBBR improvement. While the GBBR designs are intended for metamorphic solar cells, the broad and high reflection may also be useful for other optoelectronic devices such as light-emitting diodes or lasers.

41 EE - Solar Energy Technologies Office (EE-4S)↗

DOE OSTI2020

Assessing the roles of Cu- and Ag-deficient layers in chalcopyrite-based solar cells through first principles calculations

Chalcopyrites are a demonstrated material platform for realizing efficient thin-film photovoltaics, with the most well known Cu(In,Ga)Se 2 (CIGS)-based solar cells exceeding 23%. Several factors, including flexibility in tuning the absorber bandgap, enhanced surface treatments, and the electrically benign nature of common defects are responsible for the existing high performance and future promise in chalcopyrite-based photovoltaic devices. The introduction of Cu-poor phases (also known as ordered-vacancy compounds or OVCs) between the absorber and buffer layers in CIGS solar cells is known to enhance device performance; however, the overall properties and role of OVCs remain poorly understood. Using first principles calculations based on the density functional theory with screened hybrid functionals, here we explore the electronic structure and stability of OVCs and their band offsets with defect-free chalcopyrite layers in Cu- and Ag-based compounds (ABX 2 where A=Cu, Ag; B=In, Ga, Al; and X=S, Se). Using AB 3 X 5 and AB 5 X 8 stoichiometries as model OVC systems, we report on the variation of the bandgap with the A/B ratio and discuss the trends in other Cu- and Ag-based chalcopyrites beyond CuInSe 2 . We find that the valence and conduction bands are lower in energy in OVCs with respect to the parent ABX 2 chalcopyrite owing to a reduced p–d interaction between X and A atoms. We additionally perform device-level simulations to assess the implications of the results, finding that the valence band offsets of OVCs are favorable, while the conduction band offsets of chalcopyrites beyond CuInSe 2 -based absorbers may be detrimental in conventional solar cell device designs.

14 SOLAR ENERGY↗

DOE OSTI2023

Recruitment of Polo-like kinase couples synapsis to meiotic progression via inactivation of CHK-2

Meiotic chromosome segregation relies on synapsis and crossover (CO) recombination between homologous chromosomes. These processes require multiple steps that are coordinated by the meiotic cell cycle and monitored by surveillance mechanisms. In diverse species, failures in chromosome synapsis can trigger a cell cycle delay and/or lead to apoptosis. How this key step in ‘homolog engagement’ is sensed and transduced by meiotic cells is unknown. Here we report that in C. elegans , recruitment of the Polo-like kinase PLK-2 to the synaptonemal complex triggers phosphorylation and inactivation of CHK-2, an early meiotic kinase required for pairing, synapsis, and double-strand break (DSB) induction. Inactivation of CHK-2 terminates DSB formation and enables CO designation and cell cycle progression. These findings illuminate how meiotic cells ensure CO formation and accurate chromosome segregation.

59 BASIC BIOLOGICAL SCIENCES↗