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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Understanding the Nature of Capacity Decay and Interface Properties in Li//LiNi 0.5 Mn 1.5 O 4 Cells by Cycling Aging and Titration Techniques

The spinel structure LiNi 0.5 Mn 1.5 O 4 (LNMO) is a propitious cathode material for next-generation lithium-ion batteries for fast charge–discharge applications, but its capacity decay mechanism and rate-limiting process are not yet well understood. In this work, electrochemical impedance spectroscopy (EIS) with galvanostatic intermittent titration (GITT) and cycling aging techniques were employed to investigate the nature of capacity decay in disordered-phase LNMO. Different resistive components were separated after every 10 cycles. Cell overvoltages (ΔVs) due to ohmic conduction, charge transfer (CT), and concentration polarization (CP) were individually determined. Results revealed that the cell exhibited a higher ΔV at a higher discharged state. However, the ΔV value for CP was higher at a higher state of charge (SOC), and the overall LNMO/electrolyte interface played a major role in the rate-determining step. Battery life was estimated based on the results. Battery calendar life was found to be more vulnerable than cycle life. Furthermore, results also indicated that the working SOC range could be optimized based on the resistance analysis by avoiding those SOCs that have the most detrimental impact (e.g., heat generation and fire hazard).

25 ENERGY STORAGE↗
DOE OSTI2020

Amorphous Manganese Oxides: An Approach for Reversible Aqueous Zinc-Ion Batteries

Crystalline manganese oxides have attracted the most attention in aqueous zinc-ion batteries due to their diverse nanostructures and low cost. However, extensive studies on amorphous manganese oxides are lacking. Here in this paper, we report a mesoporous amorphous manganese oxide (UCT-1-250) as a cathode material with high capacity (222 mAh g –1 ), good cyclability (57% capacity retention after 200 cycles), and an acceptable discharge plateau (between 1.2 and 1.4 V). An approach to mechanistic studies was performed by comparison of UCT-1-250 and other crystalline manganese oxides through electrochemical, elemental, and structural analyses. An in situ conversion to ZnMn 2 O 4 spinel phase after initial cycling contributes to the high performance. The irreversible capacity fading is due to the formation of the woodruffite phase.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Expanding the Material Search Space for Multivalent Cathodes

Multivalent batteries are an energy storage technology with the potential to surpass lithium-ion batteries; however, their performance have been limited by the low voltages and poor solid-state ionic mobility of available cathodes. A computational screening approach to identify high-performance multivalent intercalation cathodes among materials that do not contain the working ion of interest has been developed, which greatly expands the search space that can be considered for material discovery. This approach has been applied to magnesium cathodes as a proof of concept, and four resulting candidate materials [NASICON V 2 (PO 4 ) 3 , birnessite NaMn 4 O 8 , tavorite MnPO 4 F, and spinel MnO 2 ] are discussed in further detail. In examining the ion migration environment and associated Mg 2+ migration energy in these materials, local energy maxima are found to correspond with pathway positions where Mg 2+ passes through a plane of anion atoms. While previous studies have established the influence of local coordination on multivalent ion mobility, these results suggest that considering both the type of the local bonding environment and available free volume for the mobile ion along its migration pathway can be significant for improving solid-state mobility.

25 ENERGY STORAGE↗
DOE OSTI2022

Electrochemical Sodiation Mechanism in Magnetite Nanoparticle-Based Anodes: Understanding of Nanoionics-Based Sodium Ion Storage Behavior of Fe 3 O 4

We report electrochemical ion storage behaviors of Fe 3 O 4 nanoparticles, as a representative transition metal oxide for an environmentally benign and low-cost anode for a sodium-ion battery, are thoroughly investigated through a combination of electrochemical analysis and diagnostics of Fe 3 O 4 electrode cells, X-ray-based and spectroscopic analysis of material structure evolution as functions of depth of discharge (DoD) and state of charge (SoC), and first principle modeling. The gravimetric capacity is found to be 50 mA h/g for bulk Fe 3 O 4 (50 nm average crystallite size) and 100 mA h/g--about a tenth of the theoretical prediction for complete conversion--for Fe 3 O 4 nanoparticles (8.7 nm average particle size), respectively. A fundamental and mechanistic study of material evolution as functions of DoD and SoC shows that Fe 3 O 4 does not allow electrochemical incorporation of Na + ions into the empty cation positions of the inverse spinel structure, leading to our assertion that electrochemical intercalation of Na + ions to conversion of the Fe 3 O 4 anode in sodium-ion batteries is nonviable. A density functional theory investigation points to the impracticality of the intercalation of Na + ions into Fe 3 O 4 and further validates our experimental findings. We propose several possible mechanisms corresponding to the observed low capacity, including formation of solid electrolyte interphases with unfavorable properties and adsorption of Na + ions onto surfaces of nanoparticles and/or at heterointerfaces in Fe 3 O 4 composite electrodes in a NaPF 6 -based electrolyte system.

25 ENERGY STORAGE↗
DOE OSTI2023

Surface Oxygen Depletion of Layered Transition Metal Oxides in Li-Ion Batteries Studied by Operando Ambient Pressure X-ray Photoelectron Spectroscopy

A new operando spectro-electrochemical setup was developed to study oxygen depletion from the surface of layered transition metal oxide particles at high degrees of delithiation. An NCM111 working electrode was paired with a chemically delithiated LiFePO 4 counter electrode in a fuel cell-inspired membrane electrode assembly (MEA). A propylene carbonate-soaked Li-ion conducting ionomer served as an electrolyte, providing both good electrochemical performance and direct probing of the NCM111 particles during cycling by ambient pressure X-ray photoelectron spectroscopy. The irreversible emergence of an oxygen-depleted phase in the O 1s spectra of the layered oxide particles was observed upon the first delithiation to high state-of-charge, which is in excellent agreement with oxygen release analysis via mass spectrometry analysis of such MEAs. By comparing the metal oxide-based O 1s spectral features to the Ni 2p 3/2 intensity, we can calculate the transition metal-to-oxygen ratio of the metal oxide close to the particle surface, which shows good agreement with the formation of a spinel-like stoichiometry as an oxygen-depleted phase. This new setup enables a deeper understanding of interfacial changes of layered oxide-based cathode active materials for Li-ion batteries upon cycling.

25 ENERGY STORAGE↗
DOE OSTI2023

Multifunctional Effect of Fe Substitution in Na Layered Cathode Materials for Enhanced Storage Stability

In this study, developing stable cathode materials that are resistant to storage degradation is essential for practical development and industrial processing of Na-ion batteries, as many sodium layered oxide materials are susceptible to hygroscopicity and instability when exposed to ambient air. Among the various layered compounds, Fe-substituted O 3 -type Na(Ni 1/2 Mn 1/2 ) 1-x Fe x O 2 materials have emerged as a promising option for high-performance and low-cost cathodes. While previous reports have noted the decent air-storage stability of these materials, the role and origin of Fe substitution in improving storage stability remain unclear. In this study, we investigate the air resistant effect of Fe substitution in O 3 -Na(Ni 1/2 Mn 1/2 ) 1-x Fe x O 2 cathode materials by performing systematic surface and structural characterizations. We find that the improved storage stability can be attributed to the multifunctional effect of Fe substitution, which forms a surface protective layer containing an Fe-incorporated spinel phase and decreases the thermodynamical driving force for bulk chemical sodium extraction. With these mechanisms, the Fe-containing cathodes can suppress the cascades of cathode degradation processes and better retain the electrochemical performance after air storage.

25 ENERGY STORAGE↗
DOE OSTI2024

Facet-Dependent Ni Segregation in a Micron-Sized Single-Crystal Li 1.2 Ni 0.2 Mn 0.6 O 2 Cathode

Elemental surface segregation in cathode materials is critical for determining the phase and interfacial reaction between electrode and electrolyte, which consequently affects the electrochemical properties. Single-crystal cathode of Li 1.2 Ni 0.2 Mn 0.6 O 2 and Li 1.2 Ni 0.2 Mn 0.6 O 1.95 F 0.05 with an octahedral morphology of (102) and (003) dominated facets have been manifested to show enhanced electrochemical properties. However, the surface structural features of such single crystals have not been investigated. Herein, using scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, and electron energy loss spectroscopy, we probe the elemental surface segregation characteristics in these single-crystal cathode. We reveal that Ni surface segregation shows dependence on the crystal facet such that it occurs on crystal facets with a mix of cations and anions, but not on the facets with only cations or anions. Furthermore, facet-dependent surface reconstructions are observed, featuring a spinel-like structure at the Ni-rich facet but rock-salt structure at the facet without Ni segregation. The commonly known Mn reduction appears at the single crystal surfaces, more pronounced at the facet without Ni segregation. We further reveal that fluorination leads to the stabilization of surface oxygens. In conclusion, this study provides detailed structural and chemical information about the facet-dependent Ni surface segregation and the resulted phase formation in the rather less explored micron-sized octahedral Li 1.2 Ni 0.2 Mn 0.6 O 2 and Li 1.2 Ni 0.2 Mn 0.6 O 1.95 F 0.05 single crystals, which is key to further exploration of electrochemical properties of cathode in the form of micro-sized single crystal.

25 ENERGY STORAGE↗
DOE OSTI2020

Distinct Surface and Bulk Thermal Behaviors of LiNi 0.6 Mn 0.2 Co 0.2 O 2 Cathode Materials as a Function of State of Charge

Understanding how structural and chemical transformations take place in particles under thermal conditions can inform designing thermally robust electrode materials. Such a study necessitates the use of diagnostic techniques that are capable of probing the transformations at multiple length scales and at different states of charge (SOC). In this study, the thermal behavior ofLiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC-622) was examined as a function of SOC, using an array of bulk and surface-sensitive techniques. In general, thermal stability decreases as lithium content is lowered and conversion in the bulk to progressively reduced metal oxides (spinels, rock salt) occurs as the temperature is raised. Hard X-ray absorption spectroscopy (XAS) and X-ray Raman spectroscopy (XRS) experiments, which probe the bulk, reveal that Ni and Co are eventually reduced when partially delithiated samples (regardless of the SOC) are heated, although Mn is not. Surface-sensitive synchrotron techniques, such as soft XAS and transmission X-ray microscopy (TXM), however, reveal that for 50% delithiated samples, apparent oxidation of nickel occurs at particle surfaces under some circumstances. This is partially compensated by reduction of cobalt but may also be a consequence of redistribution of lithium ions upon heating. TXM results indicate the movement of reduced nickel ions into particle interiors or oxidized nickel ions to the surface or both. These experiments illustrate the complexity of the thermal behavior of NMC cathode materials. The study also informs the importance of investigating the surface and bulk difference as a function of SOC when studying the thermal behaviors of battery materials.

25 ENERGY STORAGE↗
DOE OSTI2020

Enhancing the Electrocatalysis of LiNi 0.5 Co 0.2 Mn 0.3 O 2 by Introducing Lithium Deficiency for Oxygen Evolution Reaction

LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), as a cathode material for rechargeable lithium-ion batteries, has attracted considerable attention and been successfully commercialized for decades. NCM is also a promising electrocatalyst for the oxygen evolution reaction (OER), and the catalytic activity is highly correlated to its structure. In this paper, we successfully obtain NCM523 with three different structures: spinel NCM synthesized at low temperature (LT-NCM), disordered NCM (DO-NCM) with lithium deficiency obtained at high temperature, and layered hexagonal NCM at high temperature (HT-NCM). By introducing lithium deficiency to tune the valence state of transition metals in NCM from Ni 2+ to Ni 3+ , DO-NCM exhibits the best catalytic activity with the lowest onset potential (~1.48 V) and Tafel slope (~85.6 mV dec -1 ), whereas HT-NCM exhibits the worst catalytic activity with the highest onset potential (~1.63 V) and Tafel slope (~241.8 mV dec -1 ).

36 MATERIALS SCIENCE↗
DOE OSTI2022

Lithium-Ion Battery Materials as Tunable, “Redox Non-Innocent” Catalyst Supports

The development of general strategies for the electronic tuning of a catalyst’s active site is an ongoing challenge in heterogeneous catalysis. To this end, herein, we describe the application of Li-ion battery cathode and anode materials as redox non-innocent catalyst supports that can be continuously modulated as a function of lithium intercalation. A zero-valent nickel complex was oxidatively grafted onto the surface of lithium manganese oxide (Li x Mn 2 O 4 ) to yield isolated Ni2+ occupying the vacant interstitial octahedral site in the Li diffusion channel on the surface and subsurface of the spinel structure (Ni/Li x Mn 2 O 4 ). Additionally, the activity of Ni/Li x Mn 2 O 4 for olefin hydrogenation, as a representative probe reaction, was found to increase monotonically as a function of support reductive lithiation. Simulation of Ni/Li x Mn 2 O 4 reveals the dramatic impact of surface redox states on the viability of the homolytic oxidative addition mechanism for H 2 activation. Catalyst control through support lithiation was extended to an organotantalum complex on Li x TiO 2 , demonstrating the generality of this phenomenon.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Exploring the First High-Entropy Thin Film Libraries: Composition Spread-Controlled Crystalline Structure

Thin films of two types of high-entropy oxides (HEOs) have been deposited on 76.2 mm Si wafers using combinatorial sputter deposition. In one type of the oxides, (MgZnMnCoNi)O x , all the metals have a stable divalent oxidation state and similar cationic radii. In the second type of oxides, (CrFeMnCoNi)O x , the metals are more diverse in the atomic radius and valence state, and have good solubility in their sub-binary and ternary oxide systems. Therefore, the resulting HEO thin films were characterized using several high-throughput analytical techniques. The microstructure, composition, and electrical conductivity obtained on defined grid maps were obtained for the first time across large compositional ranges. The crystalline structure of the films was observed as a function of the metallic elements in the composition spreads, that is, the Mn and Zn in (MgZnMnCoNi)O x and Mn and Ni in (CrFeMnCoNi)O x . The (MgZnMnCoNi)O x sample was observed to form two-phase structures, except single spinel structure was found in (MgZnMnCoNi)O x over a range of Mn > 12 at. % and Zn < 44 at. %, while (CrFeMnCoNi)O x was always observed to form two-phase structures. Composition-controlled crystalline structure is not only experimentally demonstrated but also supported by density function theory calculation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Applying Configurational Complexity to the 2D Ruddlesden–Popper Crystal Structure

The layered Ruddlesden–Popper crystal structure can host a broad range of functionally important behaviors. In this work, we establish extraordinary configurational disorder in a layered Ruddlesden–Popper (RP) structure using entropy stabilization assisted synthesis. A protype A 2 CuO 4 RP cuprate oxide with five cations on the A-site sublattice is designed and fabricated into epitaxial single crystal films using pulsed laser deposition. When grown on a near lattice matched substrate, the (La 0.2 Pr 0.2 Nd 0.2 Sm 0.2 Eu 0.2 ) 2 CuO 4 film features a T'-type RP structure with uniform A-site cation mixing and square-planar CuO4 units. These observations are made with a range of combined characterizations using X-ray diffraction, atomic-resolution scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray absorption spectroscopy measurements. It is further found that heteroepitaxial strain plays an important role in crystal phase formation during synthesis. Compressive strain over ~1.5% results in the formation of a non-RP cubic phase consistent with a Cu X 2O 4 spinel structure. The ability to manipulate configurational complexity and move between 2D layered RP and 3D cubic crystal structures in cuprate and related materials promises to enable flexible design strategies for a range of functionalities, such as magnetoresistance, unconventional superconductivity, ferroelectricity, catalysis, and ion transport.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Spatial quantification of dynamic inter and intra particle crystallographic heterogeneities within lithium ion electrodes

The performance of lithium ion electrodes is hindered by unfavorable chemical heterogeneities that pre-exist or develop during operation. Time-resolved spatial descriptions are needed to understand the link between such heterogeneities and a cell's performance. Here, operando high-resolution X-ray diffraction-computed tomography is used to spatially and temporally quantify crystallographic heterogeneities within and between particles throughout both fresh and degraded Li x Mn 2 O 4 electrodes. This imaging technique facilitates identification of stoichiometric differences between particles and stoichiometric gradients and phase heterogeneities within particles. Through radial quantification of phase fractions, the response of distinct particles to lithiation is found to vary; most particles contain localized regions that transition to rock salt LiMnO 2 within the first cycle. Other particles contain monoclinic Li 2 MnO 3 near the surface and almost pure spinel LixMn2O4 near the core. Following 150 cycles, concentrations of LiMnO 2 and Li 2 MnO 3 significantly increase and widely vary between particles.

25 ENERGY STORAGE↗
DOE OSTI2024

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↗
DOE OSTI2025

Data-driven design of electrolyte additives supporting high-performance 5 V LiNi 0.5 Mn 1.5 O 4 positive electrodes

LiNi 0.5 Mn 1.5 O 4 (LNMO) is a high-capacity spinel-structured material with an average lithiation/de-lithiation potential at ca. 4.6–4.7 V vs Li + /Li, far exceeding the stability limits of electrolytes. An efficient way to enable LNMO in lithium-ion batteries is to reformulate an electrolyte composition that stabilizes both graphitic (Gr) negative electrode with solid-electrolyte-interphase and LNMO with cathode-electrolyte-interphase. In this study, we select and test a diverse collection of 28 single and dual additives for the Gr||LNMO battery system. Subsequently, we train machine learning models on this dataset and employ the trained models to suggest 6 binary compositions out of 125, based on predicted final area-specific-impedance, impedance rise, and final specific-capacity. Such machine learning-generated new additives outperform the initial dataset. This finding not only underscores the efficacy of machine learning in identifying materials in a highly complicated application space but also showcases an accelerated material discovery workflow that directly integrates data-driven methods with battery testing experiments.

batteries↗
DOE OSTI2023

In situ formed partially disordered phases as earth-abundant Mn-rich cathode materials

Abstract Earth-abundant cathode materials are urgently needed to enable scaling of the Li-ion industry to multiply terawatt hours of annual production, necessitating reconsideration of how good cathode materials can be obtained. Irreversible transition metal migration and phase transformations in Li-ion cathodes are typically believed to be detrimental because they may trigger voltage hysteresis, poor kinetics and capacity degradation. Here we challenge this conventional consensus by reporting an unusual phase transformation from disordered Li- and Mn-rich rock salts to a new phase (named δ ), which displays partial spinel-like ordering with short coherence length and exhibits high energy density and rate capability. Unlike other Mn-based cathodes, the δ phase exhibits almost no voltage fade upon cycling. We identify the driving force and kinetics of this in situ cathode formation and establish design guidelines for Li- and Mn-rich compositions that combine high energy density, high rate capability and good cyclability, thereby enabling Mn-based energy storage.

25 ENERGY STORAGE↗
DOE OSTI2025

Navigating thermal stability intricacies of high-nickel cathodes for high-energy lithium batteries

High-nickel oxide cathodes, LiNi x M 1−x O 2 (x ≥ 0.8), are preferred in automotive lithium batteries, but they face thermal instability challenges. Inconsistent literature reports and unstandardized testing protocols further complicate quantitative assessments of the thermal stability of these cathodes. Here, we present here a statistical thermal analysis based on the differential scanning calorimetry measurements of 15 representative cathode materials with different compositions, morphologies and states of charge. The findings reveal that each cathode has a critical state of charge that defines its safe operating limit, which is affected by the metal–oxygen bond strength and surface reactivity. The thermal runaway temperature is dictated by the layered Li 1−x NiO 2 to LiNi 2 O 4 spinel-like phase transition, which is thermodynamically determined by the metal–oxygen bond covalency and kinetically influenced by the cation mixing and particle size. Raman spectroscopy is used to predict the thermal runaway temperature on the basis of the linear relationship between them. Finally, we propose a thermal stability index to quantify cathode thermal stability as a guide for developing safer high-nickel cathodes.

batteries↗
DOE OSTI2025

Five-volt-class high-capacity all-solid-state lithium batteries

Advances in battery technology have been impeded by the voltage constraints of electrolytes. Here, in this study, we present a high-energy all-solid-state battery design featuring >5 V operation and an ultrahigh areal capacity of 35.3 mAh cm −2 ; these attributes were enabled by a highly conductive and ultrahigh-voltage stable fluoride solid electrolyte, LiCl–4Li 2 TiF 6 (1.7 × 10 −5 S cm −1 at 30 °C). LiCl–4Li 2 TiF 6 shields high-voltage spinel oxide cathodes, achieving 106 mAh g −1 at 2C with 75.2% retention over 500 cycles for LiNi 0.5 Mn 1.5 O 4 , sharply contrasting with the conventional LiNbO 3 counterpart, which decomposes and fails to prevent detrimental interfacial degradation. The efficacy of LiCl–4Li 2 TiF 6 is validated across various systems, including LiCoMnO 4 , LiFe 0.5 Mn 1.5 O 4 and pouch-type LiNi 0.5 Mn 1.5 O 4 ||Li (or Ag–C) all-solid-state batteries, and further demonstrated by operability down to 2.3 V with 258 mAh g −1 and ultrathick 1.8-mm electrodes. This shielding layer with >5 V stability introduces a transformative design paradigm by revisiting the previously forbidden high-voltage cathodes.

36 MATERIALS SCIENCE↗