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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 343 records · Page 19

Nanoporous Fe 2 O 3 and Soluble Fe(II) Intermediates Accelerate the Electrodeposition of Fe in NaOH(aq)

Electrochemical conversion of iron oxide to iron metal can enable low-cost batteries for long duration energy storage and zero-emissions ironmaking for steel. Iron oxides, such as hematite, can be electrochemically reduced to metallic iron in concentrated alkaline electrolytes at modest temperatures, but the relative influences of solid-state and dissolved intermediates at practical reaction rates remains unclear. Here, in this study, we prepare a homologous set of well-defined hematite particles to measure how the nanoscale morphology of oxides controls both their reactivity and apparent reduction mechanism in concentrated hydroxide. Correlated electron microscopy and rotating-ring-disk-electrode measurements revealed that nanoporous hematite and solid intermediates formed iron via a dissolution-redeposition pathway. In contrast, dense hematite particles directly formed iron metal via reactive fracture. While previous studies on iron electrowinning have primarily emphasized the role of particle diameter at the micron scale, these results demonstrate the importance of the dissolution-redeposition pathway to support rapid reaction rates and suggest that nanoscale porosity controls iron oxide reactivity at temperatures <100 °C. Therefore, iron-oxide-to-metal electrolyzers and fast-charging iron-air batteries supported by curtailed electricity can increase the rate of metal formation by accelerating fracture and dissolution in reactant oxides.

TEM↗

Asymmetric ether solvents for high-rate lithium metal batteries

Recent electrolyte solvent design based on weakening lithium-ion solvation have shown promise in enhancing cycling performance of Li-metal batteries. However, they often face slow redox kinetics and poor cycling reversibility at high rate. Here we report using asymmetric solvent molecules substantially accelerates Li redox kinetics. Asymmetric ethers (1-ethoxy-2-methoxyethane, 1-methoxy-2-propoxyethane) showed higher exchange current densities and enhanced high-rate Li 0 plating/stripping reversibility compared to symmetric ethers. Adjusting fluorination levels further improved oxidative stability and Li 0 reversibility. The asymmetric 1-(2,2,2-trifluoro)-ethoxy-2-methoxyethane, with 2 M lithium bis(fluorosulfonyl)imide, exhibited high exchange current density, oxidative stability, compact solid–electrolyte interphase (~10 nm). This electrolyte exhibited superior performance among state-of-the-art electrolytes, enabling over 220 cycles in high-rate Li (50 μm)||LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811, 4.9 mAh cm −2 ) cells and for the first time over 600 cycles in anode-free Cu | |Ni95 pouch cells (200 mAh) under electric vertical take-off and landing cycling protocols. Our findings on asymmetric molecular design strategy points to a new pathway towards achieving fast redox kinetics for high-power Li-metal batteries.

batteries↗

Cracking the failure of lithium batteries

Lithium batteries that use a solid electrolyte have the potential to improve safety and increase the amount of stored energy . This makes solid-state electrochemical cells a promising option for electric vehicles and wearable devices. However, nonuniform plating or stripping of lithium at the interface between an anode (negative electrode) and the electrolyte during charging and discharging leads to growth of detrimental lithium filaments (dendrites) that short-circuit the battery cell. This problem even occurs when the battery operates at small currents. The underlying mechanism of this failure is not well understood. On page 311 of this issue, Wang et al. (1) report that structural defects accumulate in the lithium metal anode under repeated charging and discharging at a small current. This is similar to mechanical fatigue that is observed over longer periods of intermittent straining of a material. Here, the observation could guide the design of lithium batteries with increased life span.

25 ENERGY STORAGE↗

Innovative Symmetrical Electrolyte Architecture Enables Ultra-Flat and Thermal Resilient Protonic Ceramic Electrochemical Cells

Protonic ceramic electrochemical cells (PCECs) represent a promising class of solid‐state energy conversion devices capable of high‐efficiency hydrogen production and power generation. However, the practical deployment of planar PCECs is fundamentally constrained by severe structural deformation and mechanical failure during fabrication, stemming from asymmetric shrinkage between the thin electrolyte and the thick NiO‐based support layer. Here, in this work, a functionally integrated, symmetry‐engineered double‐sided electrolyte (DE) design is unveiled, which not only suppresses thermally induced curvature but also unlocks significant gains in electrochemical performance and stability. This architecture intrinsically balances shrinkage dynamics across the cell bilaterally, enabling the fabrication of ultra‐flat 5 × 5 cm 2 cells with sub‐100 µm thickness variation. A numerical solid mechanics simulation is introduced to investigate and interpret this achievement. Beyond structural advantages, the DE configuration enhances the cell operational stability, delivering a low open‐circuit voltage degradation of 9.5 mV/100 h across 80 thermal cycles. This work establishes a compelling paradigm wherein architectural symmetry directly translates to both mechanical fidelity and functional enhancement, offering a promising route toward PCECs scale‐up.

08 - HYDROGEN↗

Effective Li-Ion Transport Quantification in Composite Cathodes for All-Solid-State Batteries via Multiscale Modeling and Experiments

The tortuosity factor of composite cathodes significantly affects the rate performance of all-solid-state batteries (ASSBs) and has significant differences from systems with liquid electrolytes. Here, in this work, we report a simulation-experiment combined approach that quantifies the effective Li-ion transport in an ASSB composite cathode, which links tortuosity factor on ∼ μm scale to terminal voltage during cycling at the cell level (on ∼ cm scale). Two independent approaches of tortuosity factor quantification are considered: fitting electrochemical cycling data and verifying at different cycling rates and calculating from segmented tomography images, with the tortuosity factor quantified from both methods reaching self-consistency. The simulated terminal voltage using the quantified tortuosity factor has a small relative error of <3% compared to the experimental measurements. We find a significantly reduced value of the Bruggeman exponent of the catholyte phase (1.75), and using shape analysis, we show that rod-shaped catholyte particles play an important role in lowering the tortuosity factor.

Yao, Archie Mingze [Univ. of Michigan, Ann Arbor, ↗

Hydrogen-bromine fuel cell advance component development

Advanced cell component development is performed by NASA Lewis to achieve improved performance and longer life for the hydrogen-bromine fuel cells system. The state-of-the-art hydrogen-bromine system utilizes the solid polymer electrolyte (SPE) technology, similar to the SPE technology developed for the hydrogen-oxygen fuel cell system. These studies are directed at exploring the potential for this system by assessing and evaluating various types of materials for cell parts and electrode materials for Bromine-hydrogen bromine environment and fabricating experimental membrane/electrode-catalysts by chemical deposition.

Charleston, Joann↗

Novel Superionic Na Conductors for Solid‐State Na batteries: Materials and Interface

This project aims to advance the fundamental understanding on how the cation or anion doping influence on the crystal structure, phase stability and ion transport of novel Na superionic conductors. Specifically, we focus on the Na 3-x A x SbS 4-y X y family solid electrolytes (A: cation dopant, X: anion dopant), a class of promising materials for all-solid-state sodium batteries owing to their high ionic conductivity and compositional tunability. By integrating materials synthesis, neutron scattering, and electrochemical characterization and theoretical simulations, this project sees to elucidate 1) how does the synthesis approaches (solid-state reaction, low-temperature reaction) on the phase purity and doping process; 2) how chemical doping (A: cation dopants such as Sn; X: anion dopants such as Se, F) modulate lattice dynamics and Na+ migration as well as interface stability toward Na metal. Specifically, this project’s proposed technology involves three objectives: (1) synthesize novel Na-ion conductors (anion or cation doped Na 3 SbS 4 ) with high phase purity and examine their structural features (e.g., phase stability); (2) understand Na-ion conductive properties of new Na-ion conductors through a combination of experimental characterizations and theoretical simulations; (3) investigate the interface stability of novel Na superionic conductors with electrode materials in solid-state Na batteries. These objectives will be achieved through combined experimental synthesis/characterizations and computational approaches. The obtained knowledge will provide a comprehensive synthesis-structure-property correlation, enabling the rational design of novel solid-state conductors with excellent conductivity and stability.

25 ENERGY STORAGE↗

A family of dual-anion-based sodium superionic conductors for all-solid-state sodium-ion batteries

The sodium (Na) superionic conductor is a key component that could revolutionize the energy density and safety of conventional Na-ion batteries. However, existing Na superionic conductors are primarily based on a single-anion framework, each presenting inherent advantages and disadvantages. Here we introduce a family of amorphous Na-ion conductors (Na 2 O 2 –MCl y , M = Hf, Zr and Ta) based on the dual-anion framework of oxychloride. Benefiting from a dual-anion chemistry and with the resulting distinctive structures, Na 2 O 2 –MCl y electrolytes exhibit room-temperature ionic conductivities up to 2.0 mS cm -1 , wide electrochemical stability windows and desirable mechanical properties. All-solid-state Na-ion batteries incorporating amorphous Na 2 O 2 –HfCl 4 electrolyte and a Na 0.85 Mn 0.5 Ni 0.4 Fe 0.1 O 2 cathode exhibit a superior rate capability and long-term cycle stability, with 78% capacity retention after 700 cycles under 0.2 C (1C = 120 mA g -1 ) at room temperature. The discoveries in this work could trigger a new wave of enthusiasm for exploring new superionic conductors beyond those based on a single-anion framework.

25 ENERGY STORAGE↗

Pathway to High Rate Capability in Interconnected Composite Electrolytes: A Case Study with a Single-Ion-Conducting Polymer

In a three-dimensional interconnected polymer/ceramic composite electrolyte (3D composite), both the polymer and ceramic electrolyte phases are individually connected with a polymer-rich surface layer to provide conformal contact with the electrodes. This work investigates how the transference number of the polymer phase affects the electrochemical properties of the 3D composite. Here, we fabricate a 3D composite using a “single-ion” conducting polymer electrolyte (PE), Li 1+x+y Al x Ti 2–x Si y P 3–y O 12 (LICGC) ceramic, and compare its electrochemical properties with the neat polymer, and with a 3D composite made with a dual-ion-conducting PE (we reported previously). Our results reveal that changing the polymer phase from a dual-ion-conducting PE to a single-ion-conducting PE results in a 9-fold increase in the limiting current density, although the interfacial impedance between the polymer and LICGC ceramic remains high (and contributes significantly to the total impedance of the 3D composite). Further, the limiting current density of the 3D composite is dictated by the PE and minimally affected by the ceramic scaffold. The ceramic scaffold, however, helps to ease the concentration gradient buildup within the PE and moderately improves the overall transference number. The LICGC scaffold does not provide any additional Li dendrite resistance due to its high reactivity with Li.

25 ENERGY STORAGE↗

Tailoring Binder Molecular Weight to Enhance Slurry-Cast NMC Cathodes for Sulfide Solid-State Batteries

We demonstrate for the first time the critical influence of binder molecular weight on the performance of slurry-cast lithium nickel manganese cobalt oxide (NMC) cathodes in sulfide-based all-solid-state batteries (SSBs). SSBs are increasingly recognized as a safer and potentially more efficient alternative to traditional Li-ion batteries, owing to the superior ionic conductivities and inherent safety features of sulfide solid electrolytes. However, the integration of high-voltage NMC cathodes with sheet-type sulfide solid electrolytes presents significant fabrication challenges. Our findings reveal that higher molecular weight binders not only enhance the discharge capacity and cycle life of these cathodes but also ensure robust adhesion and structural integrity. By optimizing binder molecular weights, we effectively shield the active materials from degradation and mechanical stress, significantly boosting the functionality and longevity of SSBs. These results underscore the paramount importance of binder properties in advancing the practical application of high-performance all-solid-state batteries.

25 ENERGY STORAGE↗

Chemo-Mechanical Behavior and Stability of High-Loading Cathodes in Solid-State Batteries

Solid-state batteries can offer higher energy density and improved safety compared to lithium ion batteries, which use flammable liquid electrolytes. Increasing the ratio of cathode active materials in composite cathodes enhances the energy density and reduces manufacturing costs. Changes in the ratio of cathode active materials alter the microstructure and chemo-mechanical response of a cathode during operation. Understanding the relationship between composition, microstructure, and chemo-mechanical interactions is critical for optimizing solid-state cathodes. Here, in this study, we engineered composite cathodes with varying ratios of LiNi 0.8 Co 0.1 Mn 0.1 O 2 and Li 6 PS 5 Cl to systematically investigate the role of microstructural evolution in long-term chemo-mechanical transformations. Chemo-mechanical stresses resulting from the volume changes of the cathode active materials led to degradation mechanisms, such as fracture and interfacial delamination. Active material fracture and delamination led to underutilization of active material and significant capacity decay during cycling. Coatings that suppress active material-active material interactions during cycling may aid in suppressing the generation of local stress hotspots.

36 MATERIALS SCIENCE↗

Operando Investigation on the Role of Densification and Chemo-Mechanics on Solid-State Cathodes

All solid-state batteries are desirable for a range of energy storage applications which require high energy density. Achieving a high energy density in a solid-state battery requires the operation of an energy dense anode with a composite solid-state cathode. Pores and/or voids within a solid state cathode are ion-blocking and thus control over the concentration and distribution of pores in the initial electrode and cycled electrode is desirable. This study provides an understanding of the interplay between electrode microstructure and mechanics on active material utilization in solid state cathodes composed of NCM 811 and Li 6 PS 5 Cl. Decreasing the solid electrolyte particle size leads to greater active material-electrolyte contact and less total deformation when exposed to an external load. Composite cathodes with greater compliance can potentially decrease strain between the active material and solid electrolyte, decrease delamination events and result in higher overall active material utilization and high capacity retention.

25 ENERGY STORAGE↗

Creep Resistance of ZrO2 Ceramic Improved by the Addition of a Small Amount of Er2O3

Zirconia (ZrO2) has great technological importance in structural, electrical, and chemical applications. It is the crucial component for state-of-the art thermal barrier coatings and an enabling component as a solid electrolyte for solid-oxide fuel cell systems. Pure ZrO2 is of limited use for industrial applications because of the phase transformations that occur. Upon the addition of stabilizers, cubic (c-ZrO2) and tetragonal (t-ZrO2) forms can be preserved. It is the stabilized and partially stabilized forms of zirconia that function as thermal barrier coatings, solid electrolytes, and oxygen sensors and that have numerous applications in the electrochemical industry. The cubic form of ZrO2 is typically stabilized through Y2O3 additions. However, Y2O3-stabilized zirconia is susceptible to deformation at high temperatures (greater than 900 C) because of the large number of slip systems and the high oxygen diffusion rates, which result in high creep rates at high temperatures. Successful use of ZrO2 at high temperatures requires that new dopant additives be found that will retain or enhance the desirable properties of cubic ZrO2 and yet produce a material with lower creep rates. At the NASA Glenn Research Center, erbium oxide (Er2O3) was identified as a promising dopant for improving the creep resistance of. ZrO2. The selection of Er2O3 was based on the strong interactions of point defects and dislocations. Single crystals of 5 mol% Er2O3- doped ZrO2 rods (4 mm in diameter) and monofilaments (200 to 300 mm in diameter and 30 cm long) were grown using the laser-heated float zone technique, and their creep behavior was measured as a function of temperature. The addition of 5 mol% Er2O3 to single-crystal ZrO2 improved its creep resistance at high temperatures by 2 to 3 orders of magnitude over state-of-the-art Y2O3-doped crystals. Detailed microstructural characterization of ZrO2-Er2O3 single crystals has identified new mechanisms for improving the creep resistance of this class of materials. Adding Er2O3 to ZrO2 results in microstructure of stable and metastable tetragonal precipitates that with thermal treatment evolve to a tweed structure of nanosize tetragonal lamellae. The superior high-temperature creep resistance of Er2O3-doped ZrO2 is attributed to nanoscale precipitation hardening. Doping with Er2O3 will significantly increase the upper-use temperature limit of ZrO2. Potential applications include using Er2O3-doped ZrO2 as a high-temperature fiber for structural applications and adding Er2O3 to reduce the sintering rates of ZrO2 thermal barrier coatings. This work was conducted at Dpto. de F sica de la Materia Condensada, Universidad de Sevilla, Spain, and at NASA Glenn.

Martinez-Fernandez, Julian↗

Eliminating chemo-mechanical degradation of lithium solid-state battery cathodes during >4.5 V cycling using amorphous Nb2O5 coatings

Abstract Lithium solid-state batteries offer improved safety and energy density. However, the limited stability of solid electrolytes (SEs), as well as irreversible structural and chemical changes in the cathode active material, can result in inferior electrochemical performance, particularly during high-voltage cycling (>4.3 V vs Li/Li + ). Therefore, new materials and strategies are needed to stabilize the cathode/SE interface and preserve the cathode material structure during high-voltage cycling. Here, we introduce a thin (~5 nm) conformal coating of amorphous Nb 2 O 5 on single-crystal LiNi 0.5 Mn 0.3 Co 0.2 O 2 cathode particles using rotary-bed atomic layer deposition (ALD). Full cells with Li 4 Ti 5 O 12 anodes and Nb 2 O 5 -coated cathodes demonstrate a higher initial Coulombic efficiency of 91.6% ± 0.5% compared to 82.2% ± 0.3% for the uncoated samples, along with improved rate capability (10x higher accessible capacity at 2C rate) and remarkable capacity retention during extended cycling (99.4% after 500 cycles at 4.7 V vs Li/Li + ). These improvements are associated with reduced cell polarization and interfacial impedance for the coated samples. Post-cycling electron microscopy analysis reveals that the Nb 2 O 5 coating remains intact and prevents the formation of spinel and rock-salt phases, which eliminates intra-particle cracking of the single-crystal cathode material. These findings demonstrate a potential pathway towards stable and high-performance solid-state batteries during high-voltage operation.

Science & Technology - Other Topics↗

Surface-Treated Composite Polymer as a Stable Artificial Solid Electrolyte Interphase Layer for Lithium Metal Anodes

Lithium (Li) metal batteries (LMBs) are one of the most promising high energy density batteries to meet the demands of electric transportation. However, the practical applications of LMBs are hindered by short cycle life and safety concern, mainly associated with side reactions between Li metal anode and liquid electrolyte and the growth of Li dendrites during cycling. In this study, we develop a stable artificial solid electrolyte interphase (aSEI), which consists of a surface-treated (S T ) PEO–Li 6.4 Ga 0.2 La 3 Zr 2 O 12 composite polymer coating layer (CPL) on Li metal anode. The developed aSEI is stable against selected electrolyte and enables a uniform electrodeposition of Li. Therefore, S T CPL@Li||LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cells exhibit improved cycling stability compared with bare Li||NMC811 cells at moderate to high current densities. Notably, using a 50 µm thick Li and a practical NMC811 cathode (~4.8 mAh cm -2 ), a capacity retention of 85% is obtained for S T CPL@Li||NMC811 cells at a current density of 2.4 mAcm -2 after 300 cycles compared with 24% for bare Li||NMC811 cells. Furthermore, S T CPL@Li||NMC811 cells demonstrate higher capacities at charge current densities of 2.4, 4.8 and 7.2 mAcm -2 compared with bare Li||NMC811 cells. Further, these findings suggest that S T CPL is promising for high current density practical LMBs.

25 ENERGY STORAGE↗

Stress Corrosion Cracking of NaSICON Membranes in Aqueous Electrolytes for Redox-Flow Batteries

The sodium super-ionic conductor (NaSICON) has versatile applications as a ceramic electrolyte for energy storage, where it can serve as an impermeable separator in solid-state batteries and redox flow systems. In particular, NaSICON systems have been proposed to be relatively stable in contact with water, making them compatible with aqueous battery chemistries. However, owing to their brittle nature and metal oxide constituents, stress-corrosion cracking (SCC) is an important failure mechanism that has not been previously explored. In this study, we assess the fracture toughness of NaSICON membranes in contact with aqueous solutions that are relevant to redox flow systems. Microindentation was performed to generate visible surface cracks and residual stress, which were observed to grow in length after exposure to aqueous solutions. This allows for a quantitative measurement of fracture toughness, which decreases after exposure to water. To contextualize these results, we develop a simplified model of the fracture behavior in aqueous redox-flow batteries that incorporate NaSICON membranes, illustrating the importance of SCC in cell design. This work provides quantitative insights into SCC as a failure mode in NaSICON, enhancing our understanding of the chemo-mechanical behavior of ceramic electrolytes in contact with aqueous solutions.

Zhang, Mengyao↗

Surprising Relationship between Silicon Anode Calendar Aging and Electrolyte Components in a Localized High-Concentration Electrolyte System

Although localized high-concentration electrolytes (LHCEs) have been shown to improve the calendar lifetime of silicon anodes, the roles of the electrolyte constituents in calendar aging are not well understood. Here, in this work, we utilize a voltage hold protocol and an LHCE with varying molar ratios of lithium bis(fluorosulfonyl)imide (LiFSI), tetramethylene sulfone (TMS), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) to probe the component roles during aging. Interestingly, the estimated calendar lifetime and irreversible lithium losses from the V-hold experiments are independent of the electrolyte formulations. Contrarily, the solid electrolyte interphase (SEI) composition depends on the electrolyte formulation. X-ray photoelectron spectroscopy shows that TMS-coordinated species decompose to form insoluble alkanes and lithium hydroxide (LiOH), while lithium fluoride (LiF) originates from the anion-coordination complex. The SEI composition does not appear to play a significant role in the silicon anode passivity, as measured by parasitic current, suggesting that the SEI-electrolyte interactions dictate the calendar aging mechanisms.

Si anode↗