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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Solution-Deposited and Patternable Conductive Polymer Thin-Film Electrodes for Microbial Bioelectronics

Microbial bioelectronic devices integrate naturally occurring or synthetically engineered electroactive microbes with microelectronics. These devices have a broad range of potential applications, but engineering the biotic–abiotic interface for biocompatibility, adhesion, electron transfer, and maximum surface area remains a challenge. Prior approaches to interface modification lack simple processability, the ability to pattern the materials, and/or a significant enhancement in currents. We report a novel conductive polymer coating that significantly enhances current densities relative to unmodified electrodes in microbial bioelectronics is reported. The coating is based on a blend of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) crosslinked with poly(2-hydroxyethylacrylate) (PHEA) along with a thin polydopamine (PDA) layer for adhesion to an underlying indium tin oxide (ITO) electrode. When used as an interface layer with the current-producing bacterium Shewanella oneidensis MR-1, this material produces a 178-fold increase in the current density compared to unmodified electrodes, a current gain that is higher than previously reported thin-film 2D coatings and 3D conductive polymer coatings. The chemistry, morphology, and electronic properties of the coatings are characterized and the implementation of these coated electrodes for use in microbial fuel cells, multiplexed bioelectronic devices, and organic electrochemical transistor based microbial sensors are demonstrated. It is envisioned that this simple coating will advance the development of microbial bioelectronic devices.

patterned bioelectronics↗
DOE OSTI2017

Formation and Diffusion of Metal Impurities in Perovskite Solar Cell Material CH 3 NH 3 PbI 3 : Implications on Solar Cell Degradation and Choice of Electrode

Abstract Solar cells based on methylammonium lead triiodide (MAPbI 3 ) have shown remarkable progress in recent years and have demonstrated efficiencies greater than 20%. However, the long‐term stability of MAPbI 3 ‐based solar cells has yet to be achieved. Besides the well‐known chemical and thermal instabilities, significant native ion migration in lead halide perovskites leads to current–voltage hysteresis and photoinduced phase segregation. Recently, it is further revealed that, despite having excellent chemical stability, the Au electrode can cause serious solar cell degradation due to Au diffusion into MAPbI 3 . In addition to Au, many other metals have been used as electrodes in MAPbI 3 solar cells. However, how the external metal impurities introduced by electrodes affect the long‐term stability of MAPbI 3 solar cells has rarely been studied. A comprehensive study of formation energetics and diffusion dynamics of a number of noble and transition metal impurities (Au, Ag, Cu, Cr, Mo, W, Co, Ni, Pd) in MAPbI 3 based on first‐principles calculations is reported herein. The results uncover important general trends of impurity formation and diffusion in MAPbI 3 and provide useful guidance for identifying the optimal metal electrodes that do not introduce electrically active impurity defects in MAPbI 3 while having low resistivities and suitable work functions for carrier extraction.

14 SOLAR ENERGY↗
DOE OSTI2016

Nanoscale elastic changes in 2D Ti 3 C 2 T x (MXene) pseudocapacitive electrodes

Designing sustainable electrodes for next generation energy storage devices relies on the understanding of their fundamental properties at the nanoscale, including the comprehension of ions insertion into the electrode and their interactions with the active material. One consequence of ion storage is the change in the electrode volume resulting in mechanical strain and stress that can strongly affect the cycle life. Therefore, it is important to understand the changes of dimensions and mechanical properties occurring during electrochemical reactions. While the characterization of mechanical properties via macroscopic measurements is well documented, in-situ characterization of their evolution has never been achieved at the nanoscale. Two dimensional (2D) carbides, known as MXenes, are promising materials for supercapacitors and various kinds of batteries, and understating the coupling between their mechanical and electrochemical properties is therefore necessary. Here we report on in-situ imaging, combined with density functional theory of the elastic changes, of a 2D titanium carbide (Ti 3 C 2 T x ) electrode in direction normal to the basal plane during cation intercalation. The results show a strong correlation between the Li+ ions content and the elastic modulus, whereas little effects of K+ ions are observed. Moreover, this strategy enables identifying the preferential intercalation pathways within a single particle.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Enhanced Rate Capability of Ion‐Accessible Ti 3 C 2 T x ‐NbN Hybrid Electrodes

Abstract Although 2D Ti 3 C 2 T x is a good candidate for supercapacitors, the restacking of nanosheets hinders the ion transport significantly at high scan rates, especially under practical mass loading (>10 mg cm −2 ) and thickness (tens of microns). Here, Ti 3 C 2 T x ‐NbN hybrid film is designed by self‐assembling Ti 3 C 2 T x with 2D arrays of NbN nanocrystals. Working as an interlayer spacer of Ti 3 C 2 T x , NbN facilitates the ion penetration through its 2D porous structure; even at extremely high scan rates. The hybrid film shows a thickness‐independent rate performance (almost the same rate capabilities from 2 to 20 000 mV s −1 ) for 3 and 50 µm thick electrodes. Even a 109 µm thick Ti 3 C 2 T x ‐NbN electrode shows a better rate performance than 25 µm thick pure Ti 3 C 2 T x electrodes. This method may pave a way to controlling ion transport in electrodes composed of 2D conductive materials, which have potential applications in high‐rate energy storage and beyond.

Wang, Hao↗
DOE OSTI2021

Probe the Localized Electrochemical Environment Effects and Electrode Reaction Dynamics for Metal Batteries using In Situ 3D Microscopy

Uncontrollable dendrite growth is closely related to non-uniform reaction environments. However, there is a lack of understanding and analysis methods to probe the localized electrochemical environment (LEE). Here the effects of the LEE are investigated, including localized ion concentrations, current density, and electric potential, on metal plating/stripping dynamics and dendrite minimization. A novel in situ 3D microscopy technique is developed to image the morphology dynamics and deposition rate of Zn plating/stripping processes on 3D Zn–Mn anodes. Using the in situ 3D microscope, the electrode morphology changes during the reactions are directly imaged and Zn deposition rate maps at different time points are obtained. It is found that reaction kinetics are highly correlated to LEE and electrode morphology. To further quantify the LEE effects, the digital twin technique is employed that allows the accurate calculation of the electrochemical environments, such as localized ion concentrations, current density, and electric potential, which cannot be directly measured from experiments. We found that the curvature of the 3D electrode surface determines the LEE and significantly influences reaction kinetics. This provides a new strategy to minimize the dendrite formation by designing and optimizing the 3D geometry of the electrode to control the LEE.

36 MATERIALS SCIENCE↗
DOE OSTI2023

High‐Loaded Electrode Filaments for Additive Manufacturing of Structural Batteries

Abstract The unique capability of 3D printing to create geometric complex structures presents a promising avenue for producing 3D electrodes aimed at enhancing power and energy densities within constrained spaces, which is challenging to achieve through traditional slurry casting methods. However, despite advancements over the years, 3D‐printed batteries have faced limitations in terms of mechanical robustness to endure significant volume changes during cycling and restricted electrochemical performance due to the lack of adequate electrode feedstock development or post‐processing treatments. Herein, a high‐loaded electrode filament with ≈65 wt.% fillers, enabling the fabrication of structural electrodes with improved electrochemical performance and superior mechanical properties, is developed. Through a combination of 3D printing and post‐processing techniques, interdigitated structures with high areal‐loading density, resulting in a full cell with an enhanced areal capacity of ≈12.28 mAh cm −2 at ≈0.92 mA cm −2 is fabricated. Moreover, the structural batteries, treated through the carbonizing process, are integrated by the carbon coating generated during carbonization, exhibiting remarkable compressive properties (with a modulus of 18.5 MPa and a strength of 1.09 MPa). Overall, the findings demonstrate the promising potential of 3D printed batteries for practical applications, while showcasing the scalability and design flexibility offered by 3D printing technology.

Chemistry↗
DOE OSTI2019

A Four‐Electron Sulfur Electrode Hosting a Cu 2+ /Cu + Redox Charge Carrier

Abstract The elemental sulfur electrode with Cu 2+ as the charge carrier gives a four‐electron sulfur electrode reaction through the sequential conversion of S↔CuS↔Cu 2 S. The Cu‐S redox‐ion electrode delivers a high specific capacity of 3044 mAh g −1 based on the sulfur mass or 609 mAh g −1 based on the mass of Cu 2 S, the completely discharged product, and displays an unprecedently high potential of sulfur/metal sulfide reduction at 0.5 V vs. SHE. The Cu‐S electrode also exhibits an extremely low extent of polarization of 0.05 V and an outstanding cycle number of 1200 cycles retaining 72 % of the initial capacity at 12.5 A g −1 . The remarkable utility of this Cu‐S cathode is further demonstrated in a hybrid cell that employs an Zn metal anode and an anion‐exchange membrane as the separator, which yields an average cell discharge voltage of 1.15 V, the half‐cell specific energy of 547 Wh kg −1 based on the mass of the Cu 2 S/carbon composite cathode, and stable cycling over 110 cycles.

Wu, Xianyong↗
DOE OSTI2019

A Four-Electron Sulfur Electrode Hosting a Cu 2+ /Cu + Redox Charge Carrier

The elemental sulfur electrode with Cu 2+ as the charge carrier gives a four–electron sulfur electrode reaction through the sequential conversion of S↔CuS↔Cu 2 S. The Cu–S redox–ion electrode delivers a high specific capacity of 3044 mAh g –1 based on the sulfur mass or 609 mAh g –1 based on the mass of Cu 2 S, the completely discharged product, and displays an unprecedently high potential of sulfur/metal sulfide reduction at 0.5 V vs. SHE. The Cu–S electrode also exhibits an extremely low extent of polarization of 0.05 V and an outstanding cycle number of 1200 cycles retaining 72 % of the initial capacity at 12.5 A g –1 . Here, the remarkable utility of this Cu–S cathode is further demonstrated in a hybrid cell that employs an Zn metal anode and an anion–exchange membrane as the separator, which yields an average cell discharge voltage of 1.15 V, the half–cell specific energy of 547 Wh kg –1 based on the mass of the Cu 2 S/carbon composite cathode, and stable cycling over 110 cycles.

25 ENERGY STORAGE↗
DOE OSTI2023

Accelerated Characterization of Electrode‐Electrolyte Equilibration

Operational durability is poorly characterized by traditional (photo)electrocatalyst discovery workflows, creating a barrier to scale-up and deployment. Corrosion is a prominent degradation mechanism whose thermodynamics depend on the concentration of corrosion products in electrolyte. We present an automated system for characterizing the equilibration of (photo)electrodes with dissolved metals in electrolyte for a given electrode, pH, and electrochemical potential. Automation of electrode selection, electrolyte preparation, and electrolyte aliquoting enables rapid identification of self-passivating electrodes and estimation of the equilibrium dissolved metals concentrations. The technique is demonstrated for metal oxide photoanodes in alkaline electrolyte, where BiVO 4 is found to continually corrode, in agreement the literature. An amorphous Ni−Sb−O photoanode is found to passivate with a Ni-rich coating on the order of 1 monolayer with less than 1 μM total dissolved metals in electrolyte, demonstrating its suitability for durable photoelectrochemical operation. The automation and throughput of the instrument are designed for incorporation in accelerated electrocatalyst discovery workflows so that durability can be considered on equal footing with activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Interrogating the Surface Intermediates and Water Oxidation Products of Boron‐Doped Diamond Electrodes with Scanning Electrochemical Microscopy

Abstract Boron‐doped diamond (BDD) electrodes are widely used in electrochemical sensing and water purification owing to their chemical and structural stability under harsh reaction conditions. Water oxidation at BDD electrodes is known to produce reactive oxygen species, but the discharged and surface chemistries involved in these processes have not been studied in depth. Here, we present scanning electrochemical microscopy (SECM) studies of electrogenerated intermediates and products formed on sp 2 carbon‐containing BDD electrodes that display stark differences in their reactivity as a function of electrolyte type and pH during water oxidation. The most reactive and abundant species discharged from the electrode were observed at pH 11 in sulfate electrolyte. With the surface interrogation mode of SECM, two kinetically distinct surface intermediates were clearly distinguished, with one forming two orders of magnitude faster than the other but displaying a slower desorption rate. The surface coverage of these species was estimated in the range of 4–7×10 −5 mol/cm 2 for the first, and 3–4.4×10 −5 mol/cm 2 for the second one. SECM imaging suggested that regions of increased product evolution have decreased electron transfer kinetics and limited surface sites for intermediate binding. This work establishes methods for studying highly reactive intermediates found in BDD and paves the way for the inspection of other interfaces where solvolysis impacts their reactivity and evolution.

Counihan, Michael J.↗
DOE OSTI2020

Sustainable Direct Recycling of Lithium-Ion Batteries via Solvent Recovery of Electrode Materials

Separation of electrode materials from their current collectors is an enabling step toward recovering critical materials from spent lithium-ion batteries. In this study, a highly efficient, cost-effective, and environmentally sustainable separation process was developed for that purpose. Ethylene glycol, a vital commodity chemical as an antifreeze and polymer precursor, is used to delaminate electrode materials at low temperatures in seconds without altering the crystalline structure and morphology of active electrode materials. The recovered current collectors were intact without any corrosion. The authors also found that the solvent could be continuously reused, leading to the development of a closed-loop ecosystem and lithium-ion battery circular economy. The ultrafast delamination was driven by the competitive inhibition of binding through the weakening of hydrogen bonding. The ethylene glycol-based separation is a sustainable electrode recovery process that paves the way for battery recycling.

25 ENERGY STORAGE↗
DOE OSTI2021

Switching CO 2 Electroreduction Selectivity Between C 1 and C 2 Hydrocarbons on Cu Gas-Diffusion Electrodes

We report that regulating the selectivity toward a target hydrocarbon product is still the focus of CO 2 electroreduction. Here, we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness, local pH, and facet in governing the selectivity toward C 1 or C 2 hydrocarbons. The selectivity toward C 2 H 4 progressively increases, while CH 4 decreases steadily upon lowering the Cu oxidation species fraction. At a relatively low electrodeposition voltage of 1.5 V, the Cu gas-diffusion electrode with the highest Cu δ+ /Cu 0 ratio favors the pathways of hydrogenation to form CH 4 with maximum Faradaic efficiency of 65.4% and partial current density of 228 mA cm -2 at -0.83 V vs RHE. At 2.0 V, the Cu gas-diffusion electrode with the lowest Cu δ+ /Cu 0 ratio prefers C–C coupling to form C 2+ products with Faradaic efficiency topping 80.1% at -0.75 V vs RHE, where the Faradaic efficiency of C 2 H 4 accounts for 46.4% and the partial current density of C 2 H 4 achieves 279 mA cm -2 . This work demonstrates that the selectivity from CH 4 to C 2 H 4 is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.

36 MATERIALS SCIENCE↗
DOE OSTI2018

An Improved Design and Versatile New Lamination Fabrication Method for Twin Electrode Thin Layer Cells Utilizing Track‐etch Membranes

Abstract Reported here are laminated membrane electrodes, an improved design and more advantageous method of fabrication for previously reported thin layer cell electrode systems developed on track‐etch membranes. The laminated membrane approach potentially further improves flow resistance by dramatically reducing the surface area to volume ratio, but also produces a cohesive device that can be more readily applied to a broad range of applications. In addition, this new fabrication method was implemented in a scalable, commercial process and resulting product demonstrations indicate that volume manufacturing is feasible. Characterization of laminated membrane electrodes reveal redox cycling amplification factors as high as 30 with linear responses to variable concentrations of redox couple. These performance characteristics are shown to be comparable to similar generator‐collector systems fabricated through much more laborious laboratory methods. This combination of added versatility, cost‐reduced fabrication and exceptional performance clearly reveals unrealized potential of track‐etch membrane approaches and boosts their candidacy as powerful new options for generator‐collector electrode systems.

Hauke, Adam↗
DOE OSTI2021

High Energy Density and Stable Three-Dimensionally Structured Se-Loaded Bicontinuous Porous Carbon Battery Electrodes

Here, 3D structured Se-loaded bicontinuous porous carbon (BPC) electrodes were fabricated through colloidal templating of BPC followed by pulsed-voltage Se electrodeposition. The resultant electrodes were found to deliver a specific capacity of 665 mA h g -1 at a rate of 0.1 C, near the theoretical value for Se. When a vinylene carbonate containing electrolyte was utilized, the capacity fade over 500 cycles at 1 C rate was as small as a few percent. Impedance measurements and physical characterization of cycled electrodes indicated the exceptionally stable cycling performance was possibly due to vinylene carbonate resulting in formation of a stable SEI during cycling. Along with cycling stability, the rate performance of the 3D Se/BPC electrodes was also good. Due to the bicontinuous structure of carbonaceous current collector at rates as high as 5 C, the deliverable capacity was about 300 mA h g -1 .

25 ENERGY STORAGE↗
DOE OSTI2020

Electrowetting‐Mediated Transport to Produce Electrochemical Transistor Action in Nanopore Electrode Arrays

Abstract Understanding water behavior in confined volumes is important in applications ranging from water purification to healthcare devices. Especially relevant are wetting and dewetting phenomena which can be switched by external stimuli, such as light and electric fields. Here, these behaviors are exploited for electrochemical processing by voltage‐directed ion transport in nanochannels contained within nanopore arrays in which each nanopore presents three electrodes. The top and middle electrodes (TE and ME) are in direct contact with the nanopore volume, but the bottom electrode (BE) is buried beneath a 70 nm silicon nitride (SiN x ) insulating layer. Electrochemical transistor operation is realized when small, defect‐mediated channels are opened in the SiN x . These defect channels exhibit voltage‐driven wetting that mediates the mass transport of redox species to/from the BE. When BE is held at a potential maintaining the defect channels in the wetted state, setting the potential of ME at either positive or negative overpotential results in strong electrochemical rectification with rectification factors up to 440. By directing the voltage‐induced electrowetting of defect channels, these three‐electrode nanopore structures can achieve precise gating and ion/molecule separation, and, as such, may be useful for applications such as water purification and drug delivery.

Kwon, Seung‐Ryong↗
DOE OSTI2022

Latticed-Confined Conversion Chemistry of Battery Electrode

The electrochemical conversion reaction, usually featured by multiple redox processes and high specific capacity, holds great promise in developing high energy rechargeable battery technologies. However, the complete structural change accompanied by spontaneous atomic migration and volume variation during the charge/discharge cycle leads to electrode disintegration and performance degradation, therefore severely restricting the application of conventional conversion-type electrodes. Herein, latticed-confined conversion chemistry is proposed, where the “intercalation-like” redox behavior is realized on the electrode with a “conversion-like” high capacity. By delicately formulating the high-entropy compounds, the pristine crystal structure can be preserved by the inert lattice framework, thus enabling an ultra-high initial Coulombic efficiency of 92.5% and a long cycling lifespan over a thousand cycles after the quasistatic charge–discharge cycle. This lattice-confined conversion chemistry unfolds a ubiquitous insight into the localized redox reaction and sheds light on developing high-performance electrodes toward next-generation high-energy rechargeable batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Dilute Regeneration-Driven Membrane Capacitive Deionization of Synthetic Seawater Using Nanopatterned Membranes and Prussian Blue Analog Electrodes

Membrane capacitive deionization (MCDI) offers energy-efficient seawater desalination but is limited at high salinity by membrane resistance and incomplete electrode regeneration. Nanopatterned ion-exchange membranes, dilute regeneration protocols, and Prussian blue analog (PBA)-functionalized electrodes are combined in a flow-by-MCDI cell. Nanopatterned ion-exchange membranes (hexagonal, octagonal, double-ring, rectangular) enhance interfacial ion transport, with hexagonal geometry delivering ≈12.5% greater surface area and the best performance. PBA-functionalized electrodes increase salt adsorption and charge-transfer kinetic rates. The integrated system lowers the area-specific resistance by 45 Ω cm2, resulting in a 500 mV reduction in the cell voltage for a current density of 2 mA cm−2 for a 35 000 ppm NaCl feed. This improves the energy-normalized salt adsorption six fold (64–382 mmol J−1). Low salinity (2000 ppm) and mixed-salt regeneration sustains a ≈39% water recovery and stable performance for at least seven cycles. Overall, combining nanopatterned membranes, which promote confinement-enhanced ion mobility, and PBA electrodes, which enhance salt adsorption, improved the energy efficiency of MCDI.

Hasan, Mahmudul↗
DOE OSTI2021

Chemical Heterointerface Engineering on Hybrid Electrode Materials for Electrochemical Energy Storage

Abstract The chemical heterointerfaces in hybrid electrode materials play an important role in overcoming the intrinsic drawbacks of individual materials and thus expedite the in‐depth development of electrochemical energy storage. Benefiting from the three enhancement effects of accelerating charge transport, increasing the number of storage sites, and reinforcing structural stability, the chemical heterointerfaces have attracted extensive interest and the electrochemical performances of hybrid electrode materials have been significantly optimized. In this review, recent advances regarding chemical heterointerface engineering in hybrid electrode materials are systematically summarized. Especially, the intrinsic behaviors of chemical heterointerfaces on hybrid electrode materials are refined based on built‐in electric field, van der Waals interaction, lattice mismatch and connection, electron cloud bias and chemical bond, and their combination. The strategies for introducing chemical heterointerfaces are classified into in situ local transformation, in situ growth, cosynthesis, and other strategy. The recent progress about the chemical heterointerfaces engineering specially focusing on metal‐ion batteries, supercapacitors, and Li–S batteries are introduced in detail. Furthermore, the classification and characterization of chemical heterointerfaces are briefly described. Finally, the emerging challenges and perspectives about future directions of chemical heterointerface engineering are proposed.

Li, Wenbin↗