Search NASA⌕ Search

SEARCH · Search NASA

Results for “electrode separator”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Deconvoluting the benefits of porosity distribution in layered electrodes on the electrochemical performance of Li-ion batteries

Thick Lithium Ion Battery (LIB) electrodes suffer from poor rate capability and high ionic impedance due to their thickness and mesostructure. Therefore, optimizing thick electrode architectures becomes crucial. In this work, we report a systematic assessment of the ionic resistance in heterogeneous porous electrodes through the combination of computational simulations using a 4D-resolved model and experimental measurements. The first part of the study is devoted to a general assessment of Electrochemical Impedance Spectroscopy (EIS) spectra, mapping the impact of ionic and electronic resistances on the overall impedances of uncalendered and calendered LiNi 1/3 Mn 1/3 Co 1/3 O 2 , LiFePO 4 and graphite electrodes. In the second part, in silico-generated electrodes with different porosities are used in computational EIS simulations to analyze the impact of the electrode porosity on the ionic impedance. As expected, the results show that a lower porosity leads to a higher ionic impedance because of a higher electrode tortuosity factor. Furthermore, in silico-generated electrodes with different porosities were stacked and assembled to create heterogeneities of porosity along the thickness, and used in computational EIS and galvanostatic discharge simulations. The computational results show that the porosity heterogeneity along the electrode thickness has a significant effect on the ionic impedance and capacity of the electrode. The electrode architecture with progressively decreasing porosity from separator to current collector shows the highest performance, a trend validated by our in house experimental EIS and galvanostatic discharge also reported in this manuscript. Overall, we conclude that the ionic resistance in a thick electrode can be effectively reduced through proper tuning of the porosity heterogeneity. The proposed heterogeneous electrode architectures presented here could enormously help building efficient thick electrodes for LIBs.

25 ENERGY STORAGE↗
DOE OSTI2022

The pH and Potential Dependence of Pb–Catalyzed Electrochemical CO 2 Reduction to Methyl Formate in a Dual Methanol/Water Electrolyte

The conversion of waste CO 2 to value-added chemicals through electrochemical reduction is a promising technology for mitigating climate change while simultaneously providing economic opportunities. The use of non-aqueous solvents like methanol allows for higher CO 2 availability and novel products. In this work, the electrochemistry of CO 2 reduction in acidic methanol catholyte at a Pb working electrode was investigated while using a separate aqueous anolyte to promote a sustainable water oxidation half-reaction. The selectivity among methyl formate (a product unique to reduction of CO 2 in methanol), formic acid, and formate was critically dependent on the catholyte pH, with higher pH conditions leading to formate and low pH favoring methyl formate. Furthermore, the potential dependence of the product distribution in acidic catholyte was also investigated, with a faradaic efficiency for methyl formate as high as 75% measured at -2.0 V vs Ag/AgCl.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Investigating the effect of heterogeneities across the electrode|multiphase polymer electrolyte interfaces in high-potential lithium batteries

Polymer electrolytes hold great promise for safe and high-energy batteries comprising solid or semi-solid electrolytes. Multiphase polymer electrolytes, consisting of mobile and rigid phases, exhibit fast ion conduction and desired mechanical properties. However, fundamental challenges exist in understanding and regulating interactions at the electrode|electrolyte interface, especially when using high-potential layered oxide active materials at the positive electrode. Here we demonstrate that depletion of the mobile conductive phase at the interface contributes to battery performance degradation. Molecular ionic composite electrolytes, composed of a rigid-rod ionic polymer with nanometric mobile cations and anions, serve as a multiphase platform to investigate the evolution of ion conductive domains at the interface. Chemical and structural characterizations enable the visualization of concentration heterogeneity and spatially resolve the interfacial chemical states over a statistically significant field of view for buried interfaces. We report that concentration and chemical heterogeneities prevail at electrode|electrolyte interfaces, leading to phase separation in polymer electrolytes. In conclusion, understanding the hidden roles of interfacial chemomechanics in polymer electrolytes enables us to design an interphase tailoring strategy based on electrolyte additives to mitigate the interfacial heterogeneity and improve battery performance.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Editorial for focus on nanophase materials for next-generation lithium-ion batteries and beyond

Lithium-ion batteries (LIBs) have revolutionized our society in many respects, and we are expecting even more favorable changes in our lifestyles with newer battery technologies. In pursuing such eligible batteries, nanophase materials play some important roles in LIBs and beyond technologies. Here, stimulated by their beneficial effects of nanophase materials, we initiated this Focus. Excitingly, this Focus collects 13 excellent original research and review articles related to the applications of nanophase materials in various rechargeable batteries, ranging from nanostructured electrode materials, nanoscale interface tailoring, novel separators, computational calculations, and advanced characterizations.

25 ENERGY STORAGE↗
DOE OSTI2023

An Overview of Challenges and Strategies for Stabilizing Zinc Anodes in Aqueous Rechargeable Zn-Ion Batteries

Aqueous rechargeable zinc ion batteries (ZIBs) have been revived and are considered a promising candidate for scalable electrochemical energy storage systems due to their intrinsic safety, low cost, large abundance, mature recyclability, competitive electrochemical performance, and sustainability. However, the deployment of aqueous rechargeable ZIBs is still hampered by the poor electrochemical stability and reversibility of Zn anodes, which is a common, inherent issue for most metal-based anodes. This review presents a comprehensive and timely overview of the challenges and strategies of Zn anodes toward durable ZIBs. First, several challenges that significantly reduce the Coulombic efficiency and cycling stability of Zn anodes are briefly discussed including dendrite formation, hydrogen evolution, and corrosion. Then, the mitigation strategies are summarized in terms of modifying the electrode/electrolyte interfaces, designing electrode structures, and optimizing electrolytes and separators. Further, we comprehensively discuss the mechanisms behind these issues and improvement strategies with respect to the anodes, electrolytes, and separators. Lastly, we provide perspectives and critical analyses of remaining challenges, outlook, and future direction for accelerating the practical application of aqueous rechargeable ZIBs.

25 ENERGY STORAGE↗
DOE OSTI2021

Application of electron backscatter diffraction techniques to quantify effects of aging on sub-grain and spatial heterogeneity in NMC cathodes

Identification and evaluation of structural heterogeneity in spent cathode materials is crucial to developing appropriate remediation strategies for novel recycling processes. Native heterogeneities may be exacerbated during the cell's operational lifetime, as sub-particle-scale variations induce anisotropic expansion and contraction upon cycling. Structural transformations resulting from repeated cycling and calendar aging predominantly occur at the secondary particle surface and at the grain boundaries (GBs) between primary particles. However, the diffusion and stress build up around and across GBs are poorly understood. In this study, electron backscatter diffraction (EBSD) is employed to track sub-grain lattice structure across a statistically relevant number of Li(Ni0.33Mn0.33Co0.33)O2 (NMC-111) particles. Specifically, differences in lattice misorientation – measured as the deviation from the grain's average orientation – are tracked as a function of position within the electrode (near current collector, middle, and near separator) and as a function of electrochemical cycling. Further, a novel method of structural analysis is developed, offering insight into sub-grain diffusion behavior by comparing lattice misorientation near the grain boundary versus in the grain bulk. The present results suggest that electrode-scale spatial heterogeneity in lattice structure is induced by initial manufacturing conditions, and that radial gradients in lattice misorientation evolve at the primary particle scale with repeated electrochemical cycling.

25 ENERGY STORAGE↗
DOE OSTI2020

Electrochemical behavior and separation of iodide in molten LiF-NaF-KF melt

This work studied the electrochemical behavior of iodide in molten LiF-NaF-KF mixture and the separation of iodide from the molten salt at 973 K using a graphite working electrode. The cyclic voltammetry (CV) and chronoamperometry (CA) measurements indicated an anodic passivation layer was formed on the graphite electrode in this melt and the layer blocked the charge transfer across the electrolyte/electrode interface. However, the added I- ions could pass through the passivation layer and were oxidized at the graphite electrode. The characterization of the obtained products proved that iodide ions was efficiently oxidized to I2 gas during electrolysis. Furthermore, the graphite anode showed excellent stability without any obvious change in dimensions after electrolysis, which showed the high current efficiency of I2 evolution reaction. Thus, the graphite electrode was possible to be served as an excellent anode to separate other anions (such as Br) from molten fluoride salts.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Gradient Architecture Design in Scalable Porous Battery Electrodes

Because it has been demonstrated to be effective toward faster ion diffusion inside the pore space, low-tortuosity porous architecture has become the focus in thick electrode designs, and other possibilities are rarely investigated. Here, to advance current understanding in the structure-affected electrochemistry and to broaden horizons for thick electrode designs, we present a gradient electrode design, where porous channels are vertically aligned with smaller openings on one end and larger openings on the other. With its 3D morphology carefully visualized by Raman mapping, the electrochemical properties between opposite orientations of the gradient electrodes are compared, and faster energy storage kinetics is found in larger openings and more concentrated active material near the separator. As further verified by simulation, this study on gradient electrode design deepens the knowledge of structure-related electrochemistry and brings perspectives in high-energy battery electrode designs.

25 ENERGY STORAGE↗
DOE OSTI2025

Cycling Performance and Structure Evolution of Co-Free Lithium- and Manganese-Rich Layered Oxides in Lithium-Ion Batteries

Lithium- and manganese-rich (LMR) layered oxides are high-capacity cathode materials that are being considered for electric vehicle (EV) lithium-ion batteries (LIBs). Here, we investigate the electrochemical cycling behavior of cells containing a cobalt-free LMR oxide, 0.3Li 2 MnO 3 ·0.7LiMn 0.5 Ni 0.5 O 2 , paired with either Li or graphite anodes. Two- and three-electrode cells are cycled under varying conditions to examine the effects of oxide activation, upper cutoff voltage, separator type, and electrolyte composition. Post-cycling characterization of harvested electrodes, with electrochemical, X-ray absorption spectroscopy, and solid-state 6 Li nuclear magnetic resonance spectroscopy techniques, are used to correlate cell performance changes with redox state evolution in the oxide and Li inventory shifts in the cell. Our results show that capacity fade and impedance rise primarily originate at the graphite anode and LMR cathode, respectively. Notably, while Ni undergoes reversible redox, Mn shows no evidence of bulk redox activity even in highly-aged electrodes: only relithiated LMR electrodes show some reduction of Mn. Graphite electrodes degrade due to particle isolation and SEI growth, exacerbated by Mn dissolution and deposition on graphite anodes. These findings highlight the coupled structural and electrochemical degradation mechanisms in LMR/graphite cells and underscore lithium inventory retention and electrode interfacial stability as critical factors for enhancing long-term performance.

Badami, Pavan P. [Argonne National Laboratory (ANL↗
DOE OSTI2020

Patterned electrode catalyst

Disclosed herein are embodiments of a patterned electrode comprising regions of catalyst and segregating regions that separate the regions of catalyst. The segregating regions may be regions of non-catalytic material. The catalyst regions may correspond to the channels of a flow field. The electrode provides improved fuel cell performance, particularly at high current densities. The electrode may be for all suitable applications, such as in a membrane electrode assembly and/or a fuel cell. Also disclosed is a method for making the patterned electrode. The method may comprise using masks to apply the catalyst and non-catalyst material to a substrate.

Macauley, Natalia↗
DOE OSTI2020

Spatial dynamics of lithiation and lithium plating during high-rate operation of graphite electrodes

The principal inhibitor of fast charging lithium ion cells is the graphite negative electrode, where favorable conditions for lithium plating occur at high charge rates, causing accelerated degradation and safety concerns. The local response of graphite, both at the electrode and particle level, when exposed to fast charging conditions of around 6C is not well understood. Consequently, the conditions that lead to the onset of lithium plating, as well as the local dynamics of lithium plating and stripping, have also remained elusive. Here, we use high-speed (100 Hz) pencil-beam X-ray diffraction to repeatedly raster along the depth of a 101 μm thick graphite electrode in 3 μm steps during fast (up to 6C) charge and discharge conditions. Consecutive depth profiles from separator to current collector were each captured in 0.5 seconds, giving an unprecedented spatial and temporal description of the state of the electrode and graphite's staging dynamics during high rate conditions. The electrode is preferentially activated near the separator, and the non-uniformity increases with rate and is influenced by free-energy barriers between graphite's lithiation stages. The onset of lithium plating and stripping was quantified, occurring only within the first 15 μm from the separator. The presence of lithium plating changed the behavior of the underlying graphite, such as causing co-existence of LiC 6 and graphite in the fully discharged state. Finally, the staging behavior of graphite at different rates was quantified, revealing a high dependency on rate and drastic hysteresis between lithiation and delithiation.

25 ENERGY STORAGE↗
DOE OSTI2025

Enhanced Laser-Induced Graphene Microfluidic Integrated Sensors (LIGMIS) for On-Site Biomedical and Environmental Monitoring

The convergence of microfluidic and electrochemical biosensor technologies offers significant potential for rapid, in-field diagnostics in biomedical and environmental applications. Traditional systems face challenges in cost, scalability, and operational complexity, especially in remote settings. Addressing these issues, laser-induced graphene microfluidic integrated sensors (LIGMIS) are presented as an innovative platform that integrates microfluidics and electrochemical sensors both comprised of laser-induced graphene. This study advances the LIGMIS concept by resolving issues of uneven fluid transport, increased hydrophobicity during storage, and sensor biofunctionalization challenges. Key innovations include Y-shaped reservoirs for consistent fluid flow, hydrophilic polyethyleneimine coatings to maintain wettability, and separable microfluidic and electrochemical components enabling isolated electrode nanoparticle metallization and biofunctionalization. Multiplexed electrochemical detection of the neonicotinoid imidacloprid and nitrate ions in environmental water samples yields detection limits of 707 nm and 10 -5.4 m with wide sensing ranges of 5–100 µm and 10 -5 –10 -1 m, respectively. Similarly, uric acid and calcium ions are detected in saliva, demonstrating detection limits of 217 nm and 10 -5.3 m with sensing ranges of 10–50 µm, and 10 -5 –10 -2.5 m, respectively. Overall, this biosensing demonstrates the capability of the LIGMIS platform for multiplexed detection in biologically complex solutions, with applications in environmental water quality monitoring and oral cancer screening.

environmental monitoring↗
DOE OSTI2022

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecular-level thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst-support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free high-performance and durable alkaline fuel cells and related technologies.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Driving Zn-MnO2 grid-scale batteries: A roadmap to cost-effective energy storage

Highlights Zn-MnO 2 batteries promise safe, reliable energy storage, and this roadmap outlines a combination of manufacturing strategies and technical innovations that could make this goal achievable. Approaches such as improved efficiency of manufacturing and increasing active material utilization will be important to getting costs as low as $100/kWh, but key materials innovations that facilitate the full 2-electron capacity utilization of MnO 2 , the use of high energy density 3D electrodes, and the promise of a separator-free battery with greater than 2V potential offer a route to batteries at $50/kWh or less. Abstract Large-scale energy storage is certain to play a significant, enabling role in the evolution of the emerging electrical grid. Battery-based storage, while not a dominant form of storage today, has opportunity to expand its utility through safe, reliable, and cost-effective technologies. Here, secondary Zn–MnO 2 batteries are highlighted as a promising extension of ubiquitous primary alkaline batteries, offering a safe, environmentally friendly chemistry in a scalable and practical energy dense technology. Importantly, there is a very realistic pathway to also making such batteries cost-effective at price points of $50/kWh or lower. By examining manufacturing examples at the Zn–MnO 2 battery manufacturer Urban Electric Power, a roadmap has been created to realize such low-cost systems. By focusing on manufacturing optimization through reduced materials waste, scalable manufacturing, and effective materials selection, costs can be significantly reduced. Ultimately, though, coupling these approaches with emerging research and development advances to enable full capacity active materials utilization and battery voltages greater than 2V are likely needed to drive costs below a target of $50/kWh. Reaching this commercially important goal, especially with a chemistry that is safe, well-known, and reliably effective stands to inject Zn–MnO 2 batteries in the storage landscape at a critical time in energy storage development and deployment. Graphical abstract

Spoerke, Erik D. (ORCID:0000000322862560)↗
DOE OSTI2020

Hybrid anodes for energy storage devices

Energy storage devices having hybrid anodes can address at least the problems of active material consumption and anode passivation that can be characteristic of traditional batteries. The energy storage devices each have a cathode separated from the hybrid anode by a separator. The hybrid anode includes a carbon electrode connected to a metal electrode, thereby resulting in an equipotential between the carbon and metal electrodes.

25 ENERGY STORAGE↗
DOE OSTI2023

Technology Strategy Assessment: Findings from Storage Innovations 2030 Supercapacitors

Electrochemical capacitors, which are commercially called supercapacitors or ultracapacitors, are a family of energy storage devices with remarkably high specific power compared with other electrochemical storage devices. Supercapacitors do not require a solid dielectric layer between the two electrodes, instead they store energy by accumulating electric charge on porous electrodes filled with an electrolyte solution and separated by an insulating porous membrane. Supercapacitors offer large specific capacitance and high power output. They can be charged and discharged very quickly, offer excellent cycle life and long operational life, and operate over a broad temperature range. The major drawbacks of supercapacitors are low energy density and a high self-discharge rate. For example, a supercapacitor passively discharges from 100% to 50% in a month compared with only 5% for a lithium-ion battery [1]. The high capital cost and low energy density of supercapacitors make the unit cost of energy stored ($/kWh) more expensive than alternatives such as batteries. Their attributes make them attractive for uses in which frequent small charges/discharges are required (e.g., ensuring power quality or providing frequency regulation). Their attributes and cost make them less attractive for long-duration energy storage, which favors technologies with low self-discharge that cost less per unit of energy stored.

25 ENERGY STORAGE↗
DOE OSTI2021

Recovery of Cathode Materials and Aluminum Foil Using a Green Solvent

Effective separation of cathode materials and current collectors is one of the most enabling steps, yet a very challenging step, in recycling electrode scraps and spent Li-ion cells. Here, a green solvent, triethyl phosphate, was used to recover invaluable cobalt-containing cathodes, such as NMC622, by dissolving the polymeric binder of poly(vinylidene fluoride). Electrochemically active materials were separated from cathode scraps collected at the manufacturing step of electrodes through a solvent-based separation method without jeopardizing their physical characteristics, crystalline structure, and electrochemical performance. In this work, we found that the recovered aluminum foils were clean without any sign of corrosion and that the polymeric binder could be recovered via a non-solvent-induced phase separation. Additionally, recovery of cathode materials from spent cells was achieved using refined separation parameters based on the recycling of cathode scraps. It is anticipated that this green solvent-based separation for cathode recovery will attract significant interest by the lithium-ion battery manufacturing and recycling communities.

25 ENERGY STORAGE↗