Microstructure Optimization of LSM/YSZ Air Electrodes for Catalyst Infiltration
Poster for 2023 Fossil Energy and Carbon Management Spring R&D Project Review Meeting.
Liu, Jian↗
SEARCH · Search NASA
Results for “electrode microstructure”
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.
In Situ and Surface-Enhanced Raman Spectroscopy Study of Electrode Materials in Solid Oxide Fuel Cells
Solid oxide fuel cells (SOFCs) represent next-generation energy sources with high energy conversion efficiencies, low pollutant emissions, good flexibility with a wide variety of fuels, and excellent modularity suitable for distributed power generation. As an electrochemical energy conversion device, the SOFC’s performance and reliability depend sensitively on the catalytic activity and stability of electrode materials. To date, however, the development of electrode materials and microstructures is still based largely on trial-and-error methods because of the inadequate understanding of electrode process mechanisms. Therefore, the identification of key descriptors/properties for electrode materials or functional heterogeneous interfaces, especially under in situ/operando conditions, may provide guidance for the design of optimal electrode materials and microstructures. Here, Raman spectroscopy is ideally suited for the probing and mapping of chemical species present on electrode surfaces under operating conditions. And to boost the sensitivity toward electrode surface species, the surface-enhanced Raman spectroscopy (SERS) technique can be employed, in which thermally robust SERS probes (e.g., Ag@SiO 2 core–shell nanoparticles) are designed to make in situ/operando analysis possible. Furthermore, this review summarizes recent progresses in the investigation of SOFC electrode materials through Raman spectroscopic techniques, including topics of early stage carbon deposition (coking), coking-resistant anode modification, sulfur poisoning, and cathode degradation. In addition, future perspectives for utilizing the in situ/operando SERS for investigations of other electrochemical surfaces and interfaces are also discussed.
25 ENERGY STORAGE↗
Microstructure Characterization and Modeling for Improved Electrode Design
This presentation describes research work led by NREL with team members from Argonne National Laboratory and Texas A&M University in microstructure analysis, modeling and validation under DOE's Computer-Aided Engineering of Batteries (CAEBAT) program. The goal of the project is to close the gaps between CAEBAT models and materials research by creating predictive models that can be used for electrode design.
33 ADVANCED PROPULSION SYSTEMS↗
A Comprehensive Experimental Study on Microstructure‐Graded Graphite Anodes for Enhancing Fast‐Charging Capability of Lithium‐Ion Batteries
Lithium‐ion batteries with high gravimetric capacity density and improved cycle life performance under fast‐charging conditions are crucial for widespread electric vehicle (EV) adoption. This study investigates how designing graphite anode microstructure, specifically porosity, and particle‐size gradients, improves lithium‐ion (Li + ) transport during fast‐charging conditions. Three‐layered graphite anodes with varying porosity (24%, 36%, 46%) and particle size gradients (3, 5, 10 μm) were compared to a conventional single‐layered electrode in half‐cell configurations. At room temperature and high discharge rate (2C), both gradient structures showed significantly enhanced capacity retention (80% and 67% vs. 50%) compared to the conventional electrode, highlighting the effectiveness of microstructure engineering for fast charging. The study also investigated the temperature's impact on cycle life. After 200 cycles at 2°C and 45°C, all gradient structures demonstrated superior capacity retention (≈80%) compared to the conventional electrode (35%), suggesting the gradients mitigate degradation rate at high temperatures. Electrochemical impedance spectroscopy confirmed superior Li+ diffusion and lower resistivity in gradient electrodes. Simulations explored the influence of gradient profiles on reaction kinetics across the electrode thickness. Overall, this research demonstrates that the fast‐charging capability of graphite electrodes can be greatly enhanced by engineering the electrode microstructure, thereby making EV technology more accessible and appealing.
Ahmadi, Soma↗
High spatial resolution neutron imaging of lithium-ion batteries: Correlating microstructure and lithium transport
Thick electrodes for lithium-ion batteries can increase the overall energy density, but increasing the electrode thickness introduces charge transport limitations. These limitations may be mitigated through proper electrode structuring. Here, high spatial resolution neutron imaging was used to understand the correlation between microstructure and lithium transport in lithium-ion anodes. Batteries with distinct graphite anode microstructures were produced and studied with high spatial resolution in operando neutron radiography to observe the effects of structure on transport. High spatial resolution neutron computed tomography was performed following in operando neutron radiography. X-ray computed tomography and scanning electron microscopy were used to observe the finer scale anode structure to complement neutron imaging. Solvent-free anodes containing a tightly-packed layered structure confined lithium movement close to the separator. This structure limited capacity, but supported better rate capability. Conversely, a more open pore structure in the wet cast anodes yielded higher capacity with reduced rate capability. Together, these results show that lithium distributions can be controlled by the macroscopic structure of the electrodes, the microstructural pore network, and the microscale active areas that support electrochemical reactions. Furthermore, multimodal imaging applying the complementary strengths of neutron and X-ray methods is shown as a tool for advancing battery design.
25 ENERGY STORAGE↗
3D microstructure design of lithium-ion battery electrodes assisted by X-ray nano-computed tomography and modelling
Driving range and fast charge capability of electric vehicles are heavily dependent on the 3D microstructure of lithium-ion batteries (LiBs) and substantial fundamental research is required to optimise electrode design for specific operating conditions. Here we have developed a full microstructure-resolved 3D model using a novel X-ray nano-computed tomography (CT) dual-scan superimposition technique that captures features of the carbon-binder domain. This elucidates how LiB performance is markedly affected by microstructural heterogeneities, particularly under high rate conditions. The elongated shape and wide size distribution of the active particles not only affect the lithium-ion transport but also lead to a heterogeneous current distribution and non-uniform lithiation between particles and along the through-thickness direction. Building on these insights, we propose and compare potential graded-microstructure designs for next-generation battery electrodes. To guide manufacturing of electrode architectures, in-situ X-ray CT is shown to reliably reveal the porosity and tortuosity changes with incremental calendering steps.
33 ADVANCED PROPULSION SYSTEMS↗
Electrochemistry Coupled Mesoscale Complexations in Electrodes Lead to Thermo-Electrochemical Extremes
Thermo-electrochemical extremes continue to remain a challenge for lithium-ion batteries. Contrary to the conventional approach, we propose herein that the electrochemistry-coupled and microstructure-mediated cross talk between the positive and negative electrodes ultimately dictates the off-equilibrium-coupled processes, such as heat generation and the propensity for lithium plating. The active particle morphological differences between the electrode couple foster a thermo-electrochemical hysteresis, where the difference in heat generation rates changes the electrochemical response. The intrinsic asymmetry in electrode microstructural complexations leads to thermo-electrochemical consequences, such as cathode-dependent thermal excursion and co-dependent lithium plating otherwise believed to be anode-dependent.
25 ENERGY STORAGE↗
Silicon sealing for high performance battery anode materials
A battery electrode is provided that includes a porous silicon microstructure precursor, a silicon shell coating deposited on the silicon microstructure precursor, and a graphene coating deposited on the silicon shell coating, where the graphene coating encapsulates the silicon shell coating forming a graphene-encapsulated silicon-shell-protected porous silicon microstructure precursor battery electrode.
Cui, Yi↗
4D nano-tomography of electrochemical energy devices using lab-based X-ray imaging
Electrochemical energy devices offer a variety of alternate means for low-carbon, multi-scale energy conversion and storage. Reactions in these devices are supported by electrodes with characteristically complex microstructures. To meet the increasing capacity and lifetime demands across a range of applications, it is essential to understand microstructural evolutions at a cell and electrode level which are thought to be critical aspects influencing material and device lifetime and performance. X-ray computed tomography (CT) has become a highly employed method for non-destructive characterisation of such microstructures with high spatial resolution. However, sub-micron resolutions present significant challenges for sample preparation and handling particularly in 4D studies, (three spatial dimensions plus time). Here, microstructural information is collected from the same region of interest within two electrode materials: a solid oxide fuel cell and the positive electrode from a lithium-ion battery. Using a lab-based X-ray instrument, tomograms with sub-micron resolutions were obtained between thermal cycling. The intricate microstructural evolutions captured within these two materials provide model examples of 4D X-ray nano-CT capabilities in tracking challenging degradation mechanisms. Furthermore, this technique is valuable in the advancement of electrochemical research as well as broader applications for materials characterisation.
25 ENERGY STORAGE↗
Stochasticity at Scales Leads to Lithium Intercalation Cascade
Porous intercalation electrodes are synonymous with the promise of lithium-ion batteries toward electromobility. These electrodes exhibit stochastic geometrical features spanning different length scales. The implication of microstructural inhomogeneity on the lithium intercalation dynamics is hitherto unknown. In this work, starting from three-dimensional (3D), X-ray tomograms of intercalation electrode microstructures, we characterize the microstructural variability in porous intercalation electrodes. Furthermore, a physics-based analysis of electrochemical response reveals that the stochastic features can cause preferential lithiation fronts.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Simulating Microstructure Evolution in Ni-YSZ Electrodes of Solid Oxide Cell Under Operating Conditions
TMS 2022, Virtual, February 27–March 3, 2022
Lei, Yinkai↗
Probing Impedance and Microstructure Evolution in Lithium–Sulfur Battery Electrodes
Not provided.
Chemistry↗
Parameters of a Microstructure of Erosion Regions during the Action of a Spark Discharge on a Copper Electrode Surface in Air
The parameters of a microstructure of regions of action of a spark discharge on a copper plane electrode surface in air at atmospheric pressure in the spike–plane gap both for positive and negative polarity of a spike have been studied using scanning electron microscopy. It has been found that regions of action have the appearance of rounded spots or groups of spots with an internal structure in the form of agglomeration of a large number of microcraters. It has been shown that the statistical distributions of microcrater diameters and intermicrocrater distances are characterized by several local maximums that determine the presence of several predominant values of these parameters in a spot. It has been revealed that the microstructure of a spot is characterized by the fractal behavior and the fractal dimensionalities of the microstructure have been determined.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Mesoscale characterization of local property distributions in heterogeneous electrodes
We report the performance of electrochemical devices depends on the three-dimensional (3D) distributions of microstructural features in their electrodes. Several mature methods exist to characterize 3D microstructures over the microscale (tens of microns), which are useful in understanding homogeneous electrodes. However, methods that capture mesoscale (hundreds of microns) volumes at appropriate resolution (tens of nm) are lacking, though they are needed to understand more common, less ideal electrodes. Using serial sectioning with a Xe plasma focused ion beam combined with scanning electron microscopy (Xe PFIB-SEM), two commercial solid oxide fuel cell (SOFC) electrodes are reconstructed over volumes of 126 × 73 × 12.5 and 124 × 110 × 8 μm 3 with a resolution on the order of ≈ 50 3 nm 3 . The mesoscale distributions of microscale structural features are quantified and both microscale and mesoscale inhomogeneities are found. We analyze the origin of inhomogeneity over different length scales by comparing experimental and synthetic microstructures, generated with different particle size distributions, with such synthetic microstructures capturing well the high-frequency heterogeneity. Effective medium theory models indicate that significant mesoscale variations in local electrochemical activity are expected throughout such electrodes. Finally, these methods offer improved understanding of the performance of complex electrodes in energy conversion devices.
30 DIRECT ENERGY CONVERSION↗
3D-printed electrode, gas diffusion electrode (GDE) and gas diffusion layer (GDL) for fuel cell applications
An electrocatalytically active ink composition is used with an additive manufacturing process, such as 3D printing, to produce electrodes having consistent, adaptable, and high surface area structures. The electrocatalytically active ink composition includes a mixed powdered precursor and a polymer matrix. The mixed powdered precursor includes a carbon source, a dopant source, and/or a metal-containing catalyst. The material and electrochemical properties of the ink composition may facilitate 3D printing of electrochemically active electrodes for energy conversion and storage devices, and may allow fine-tuning of macro- and microstructures to develop electrodes having improved activity and efficiency.
Lee, Kwan-Soo↗
Analysis of Long-Range Interaction in Lithium-Ion Battery Electrodes
The lithium-ion battery (LIB) electrode represents a complex porous composite, consisting of multiple phases including active material (AM), conductive additive, and polymeric binder. This study proposes a mesoscale model to probe the effects of the cathode composition, e.g., the ratio of active material, conductive additive, and binder content, on the electrochemical properties and performance. The results reveal a complex nonmonotonic behavior in the effective electrical conductivity as the amount of conductive additive is increased. Insufficient electronic conductivity of the electrode limits the cell operation to lower currents. Once sufficient electron conduction (i.e., percolation) is achieved, the rate performance can be a strong function of ion-blockage effect and pore phase transport resistance. In conclusion, even for the same porosity, different arrangements of the solid phases may lead to notable difference in the cell performance, which highlights the need for accurate microstructural characterization and composite electrode preparation strategies.
25 ENERGY STORAGE↗
Performance of solid oxide fuel cells approaching the two-dimensional limit
We model electrochemical kinetics and physical conduction mechanisms for carrier transport in electrolyte membranes to determine the limits of dimensionality reduction (down to 1 nm) on maximum power output of solid oxide fuel cells with symmetric Pt electrodes. Using Y-doped ZrO{sub 2}, we find a minimum thickness of ∼6 nm to realize near ideal chemical potential in such fuel cells, which is limited by electronic breakdown when approaching the dielectric breakdown strength. For larger electrolyte thicknesses, the greatest source of electronic leakage influencing power loss is from Ohmic transport of minority carriers and emission of trapped carriers. For porous metallic electrodes, an ideal microstructure with the particle size comparable to particle spacing dimensions is found to accurately model experimental results. The role of electronic trap states in the electrolyte band gap on power density characteristics is highlighted.
36 MATERIALS SCIENCE↗