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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Al Substitution for Mn during Co-Precipitation Boosts the Electrochemical Performance of LiNi 0.8 Mn 0.1 Co 0.1 O 2

We report nickel-rich layered oxides, such as LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC 811), are considered as one of the most promising candidates for the next-generation cathode because of their high energy densities and relatively low cost. However, the poor first Coulombic efficiency of NMC 811 leads to around a 15% capacity loss in the first cycle at a cut-off voltage of 4.4 V. Moreover, the structure degradation during cycling results in capacity fading and safety concerns, due to potential oxygen loss after charging. Here, with aluminum substitution for manganese through a developed continuous co-precipitation approach, the electrochemical performance of NMC 811 cathodes has been greatly enhanced. Among different Al% substituted samples, LiNi 0.8 Mn 0.06 Co 0.1 Al 0.04 O 2 cathodes reduced by 50% the first capacity loss of pristine NMC 811(18.0 vs 35.9 mAh g -1 ) and improved the capacity retention from 81.4 to 96.4% after 60 cycles at 0.5C in the voltage range of 2.8–4.4 V.

25 ENERGY STORAGE↗
DOE OSTI2021

Unraveling transition-metal-mediated stability of spinel oxide via in situ neutron scattering

The energy materials performance is intrinsically determined by structures from the average lattice structure to the atom arrangement, valence, and distribution of the containing transition metal (TM) elements. Understanding the mechanism of the structure transition and atom rearrangement via synthesis or processing is key to expediting the exploration of excellent energy materials. In this work, in situ neutron scattering is employed to reveal the real-time structure evolution, including the TM-O bonds, lattice, TM valence and the migration of the high-voltage spinel cathode LiNi 0.5 Mn 1.5 O 4 . The transition-metal-mediated spinel destabilization under the annealing at the oxygen-deficient atmosphere is pinpointed. Additionally, the formation of Mn 3+ is correlated to the TM migration activation, TM disordered rearrangement in the spinel, and the transition to a layered-rocksalt phase. The further TM interdiffusion and Mn 2+ reduction are also revealed with multi-stage thermodynamics and kinetics. The mechanisms of phase transition and atom migrations as functions of temperature, time and atmosphere present important guidance on the synthesis in various-valence element containing oxides.

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

Enhancing Chemical Interaction of Polysulfide and Carbon through Synergetic Nitrogen and Phosphorus Doping

The shuttling effect of the polysulfide (PS) is the most detrimental factor that causes capacity fading of Li–S batteries. By substituting carbon atoms with heteroatoms, the host materials can provide a chemical interaction with PS to trap it within the electrochemically active range of the cathode. In this study, first-principles-based calculations identify the most stable nitrogen (N) and phosphorus (P) codoped atomic structures and their corresponding adsorption energy toward different PS species. Based on the simulated predictions, we introduce a glucosamine-derived carbon nanotube aerogel (CNA) with a secondary dopant of P during the synergetic polymerization and carbonization process. The N–P codoped CNA and S composite (NPCNA-S) renders a highly stable performance even at a sulfur loading of 3.5 mg cm –2 . In conclusion, the specific capacity is >900 mAh g –1 and the stabilized capacity retention is >70% over 450 cycles at 0.2 C rate (1 C = 1675 mA g –1 ).

25 ENERGY STORAGE↗
NASA NTRS1975

Electrochemical generation of oxygen. 1: The effects of anions and cations on hydrogen chemisorption and anodic oxide film formation on platinum electrode. 2: The effects of anions and cations on oxygen generation on platinum electrode

The effects were studied of anions and cations on hydrogen chemisorption and anodic oxide film formation on Pt by linear sweep voltammetry, and on oxygen generation on Pt by potentiostatic overpotential measurement. The hydrogen chemisorption and anodic oxide film formation regions are greatly influenced by anion adsorption. In acids, the strongly bound hydrogen occurs at more cathodic potential when chloride and sulfate are present. Sulfate affects the initial phase of oxide film formation by produced fine structure while chloride retards the oxide-film formation. In alkaline solutions, both strongly and weakly bound hydrogen are influenced by iodide, cyanide, and barium and calcium cations. These ions also influence the oxide film formation. Factors considered to explain these effects are discussed. The Tafel slope for oxygen generation was found to be independent on the oxide thickness and the presence of cations or anions. The catalytic activity indicated by the exchange current density was observed decreasing with increasing oxide layer thickness, only a minor dependence on the addition of certain cations and anions was found.

Huang, C. J.↗
NASA NTRS1984

Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

Stonehart, P.↗
NASA NTRS2009

Symmetrical, bi-electrode supported solid oxide fuel cell

The present invention is a symmetrical bi-electrode supported solid oxide fuel cell comprising a sintered monolithic framework having graded pore electrode scaffolds that, upon treatment with metal solutions and heat subsequent to sintering, acquire respective anodic and cathodic catalytic activity. The invention is also a method for making such a solid oxide fuel cell. The graded pore structure of the graded pore electrode scaffolds in achieved by a novel freeze casting for YSZ tape.

Cable, Thomas L.↗
DOE OSTI2021

Reinforced matrix for molten carbonate fuel cell and method for manufacturing the same

A reinforced electrolyte matrix for a molten carbonate fuel cell includes a porous ceramic matrix, a molten carbonate salt provided in the porous ceramic matrix, and at least one reinforcing structure comprised of at least one of yttrium, zirconium, cerium or oxides thereof. The reinforcing structure does not react with the molten carbonate salt. The reinforced electrolyte matrix separates a porous anode and a porous cathode in the molten carbonate fuel cell.

Surendranath, Arun↗
DOE OSTI2023

Constructing “Li-rich Ni-rich” oxide cathodes for high-energy-density Li-ion batteries

The current exploration of high-energy-density cathode materials for Li-ion batteries is mainly concentrated on either so-called “Li-rich” or “Ni-rich” oxides. However, both are suffering from formidable practical challenges. Here, we combine these two concepts to obtain “Li-rich Ni-rich” oxides in pursuit of more practical high-energy-density cathodes. As a proof of concept, we synthesized an array of Li 1+y Ni( 3-5y)/3 Mo 2y/3 O 2 oxides, whose structures were identified to be the coexistence of LiNiO 2 -rich and Li 4 MoO 5 -rich domains with the aid of XRD, TEM, and NMR techniques. Such an intergrowth structure of 5–20 nm size enables excellent mechanical and structural reversibility for the layered rock-salt LiNiO 2 -rich domain upon cycling thanks to the robust cubic rock-salt Li 4 MoO 5 -rich domain enabling an “epitaxial stabilization” effect. As a result, we achieved high capacities (>220 mA h g -1 ) with Ni contents as low as 80%; the Li 1.09 Ni 0.85 Mo 0.06 O 2 member (y = 0.09) shows much improved cycling performances (91% capacity retention for 100 cycles at C/10) compared with pure LiNiO 2 . Further, this work validates the feasibility of constructing Li-rich Ni-rich compounds in the form of intergrowing domains and hence unlocks vast possibilities for future cathode design.

25 ENERGY STORAGE↗
DOE OSTI2020

Nonflammable Lithium Metal Full Cells with Ultra-high Energy Density Based on Coordinated Carbonate Electrolytes

Coupling thin Li metal anodes with high-capacity/high-voltage cathodes such as LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) is a promising way to increase lithium battery energy density. Yet, the realization of high-performance full cells remains a formidable challenge. Here, we demonstrate a new class of highly coordinated, nonflammable carbonate electrolytes based on lithium bis(fluorosulfonyl)imide (LiFSI) in propylene carbonate/fluoroethylene carbonate mixtures. Utilizing an optimal salt concentration (4 M LiFSI) of the electrolyte results in a unique coordination structure of Li + -FSI - -solvent cluster, which is critical for enabling the formation of stable interfaces on both the thin Li metal anode and high-voltage NCM811 cathode. Under highly demanding cell configuration and operating conditions (Li metal anode = 35 μm, areal capacity/charge voltage of NCM811 cathode = 4.8 mAh cm -2 /4.6 V, and anode excess capacity [relative to the cathode] = 0.83), the Li metal-based full cell provides exceptional electrochemical performance (energy densities = 679 Wh kg cell -1 /1,024 Wh L cell -1 ) coupled with nonflammability.

25 ENERGY STORAGE↗
DOE OSTI2024

The role of Li doping in layered/layered Na x Li y Ni 0.4 Fe 0.2 Mn 0.4 O 2 intergrowth electrodes for sodium ion batteries

Here, the layered NaTMO 2 (TM = Ni, Fe, Mn) materials with the O3-type structure are attractive as positive electrodes for sodium ion batteries because of their high theoretical capacity. Additionally, Li doping in these materials has been shown to offer substantial enhancements to their electrochemical properties by promoting the formation of intergrowth structures, which are combinations of specific phases. However, the mechanism by which the intergrowth modifies the electrochemical properties is often unclear. Systematic variation of Li content in Na x Li y Ni 0.4 Fe 0.2 Mn 0.4 O 2 (NFM-Li y ) was conducted to identify its role in structural modification and electrochemical performance. Li contents of 0.15 and greater generate a layered/layered Na-O3/Li-O’3 intergrowth structure. 7 Li and 23 Na nuclear magnetic resonance and x-ray absorption spectroscopy identify that when the total solubility for alkali ions in the layered structure is exceeded, Li continues to form the Li-O’3 phase while the excess Na forms residual sodium compounds such as Na 2 O. Higher Li content is associated with improved capacity retention in the initial cycles from the superior stability of the mechanically linked NaO3/Li-O’3 structure that suppresses the P3 to OP2 phase transition during charge. However, high Li contents are associated with increased rates of parasitic side reactions that reduce long-term cycling stability. These side reactions are associated with the instability of the cathode-electrolyte interphase, which can be partially mitigated by atomic layer deposition (ALD) coating with alumina, which significantly enhances the capacity retention and Coulombic efficiency over many cycles. Overall, we find that the layered/layered Na-O3/Li-O’3 intergrowth structure is able to provide structural stability and suppress undesired phase transformations but is overwhelmed by the increased reactivity of the surface if not protected by surface coating.

25 ENERGY STORAGE↗
DOE OSTI2022

Conformal PEDOT Coating Enables Ultra-High-Voltage and High-Temperature Operation for Single-Crystal Ni-Rich Cathodes

Single-crystal Ni-rich Li[Ni x Mn y Co 1-x-y ]O 2 (SC-NMC) cathodes represent a promising approach to mitigate the cracking issue of conventional polycrystalline cathodes. However, many reported SC-NMC cathodes still suffer from unsatisfactory cycling stability, particularly under high charge cutoff voltage and/or elevated temperature. Herein, we report an ultraconformal and durable poly(3,4-ethylenedioxythiophene) (PEDOT) coating for SC-NMC cathodes using an oxidative chemical vapor deposition (oCVD) technique, which significantly improves their high-voltage (4.6 V) and high-temperature operation resiliency. The PEDOT coated SC LiNi 0.83 Mn 0.1 Co 0.07 O 2 (SC-NMC83) delivers an impressive capacity retention rate of 96.7% and 89.5% after 100 and 200 cycles, respectively. Significantly, even after calendar aging at 45 degrees C and 4.6 V, the coated cathode can still retain 85.3% (in comparison with 59.6% for the bare one) of the initial capacity after 100 cycles at a 0.5 C rate. Synchrotron X-ray experiments and interface characterization collectively reveal that the conformal PEDOT coating not only effectively stabilizes the crystallographic structure and maintains the integrity of the particles but also significantly suppresses the electrolyte's corrosion, resulting in improved electrochemical/thermal stability. Our findings highlight the promise of an oCVD PEDOT coating for single-crystal Ni-rich cathodes to meet the grand challenge of high-energy batteries under extreme conditions.

25 ENERGY STORAGE↗
DOE OSTI2025

Vanadium-enhanced Na 2 FePO 4 F cathodes for high-performance sodium-ion batteries

Sodium fluorophosphate Na 2 FePO 4 F holds great potential for sodium-ion batteries due to its high theoretical capacity, excellent structural stability, abundant resources, and affordability. However, its poor electronic and ionic conductivities limit its practical applications. Therefore, ion doping and carbon coating have been employed as synergistic strategies in this study to overcome these limitations. A one-step, energy-efficient solid-state method using sucrose as a carbon coating source was used to synthesize Na 2 FePO 4 F/C (NFPF/C) and its doped variant, Na 2 Fe 0.85 V 0.1 PO 4 F/C (NFVPF/C). 23 Na-MAS-NMR spectra confirm the existence of two distinct sites for sodium (Na1/Na2). The ex-situ 23 Na-MAS-NMR performed at different states-of-charge reveals the activity of only one sodium. The scanning electron microscopy findings reveal a reduction in the particle size with V-introduction, enhancing the energetic performances. NFVPF/C delivers higher specific capacity of 122 mAh g −1 compared to 116 mAh g −1 for NFPF/C at 0.1C. It also demonstrates improved cycling stability, retaining 81 % of its initial capacity after 120 cycles, in contrast to 46 % for the pristine material. The doped phase outperforms the pristine at higher current rates, delivering specific capacities of 81 and 55 mAh g −1 at 2C and 3C, respectively, compared to 35 and 17 mAh g −1 for NFPF/C.

25 ENERGY STORAGE↗
DOE OSTI2023

Designing Electrolytes With Controlled Solvation Structure for Fast‐Charging Lithium‐Ion Batteries

Recharging battery-powered electric vehicles (EVs) in a similar timeframe as those used for refueling gas-powered internal combustion vehicles is highly desirable for rapid penetration of the EV market. It is well known that the electrolyte in a battery plays a critical role in fast-charging capability of the battery because it determines the rate of ion transport together with its derived electrode/electrolyte interphases on both cathode and anode of the battery. In this study, the effects of contents of salt, coordinating solvent, and noncoordinating diluent on salt dissociation degree and electrolyte ionic conductivity are investigated, and a controlled solvation structure electrolyte is developed to improve the lithium ion mobility and conductivity in the electrolyte and to enhance the kinetics and stability of the electrode/electrolyte interphases in the battery. This electrolyte enables fast-charging capability of high energy density lithium-ion batteries (LIBs) at up to 5 C rate (12-min charging), which significantly outperforms the state-of-the-art electrolyte. The controlled solvation structure sheds light on the future electrolyte design for fast-charging LIBs.

25 ENERGY STORAGE↗
DOE OSTI2022

Structural design strategies for superionic sodium halide solid electrolytes

We report sodium all-solid-state batteries (ASSBs) with superionic solid electrolytes (SEs) show substantial potential for large-scale energy-storage applications. Recently, lithium halide SEs have attracted attention owing to their potential compatibility with high-voltage cathode materials and high ionic conductivity. Although sodium halide SEs are believed to exhibit good electrochemical stability, very few compounds have been reported. This study provides design principles for superionic sodium halide SEs through systematic theoretical investigations of Na 3 MX 6 (X = Cl, Br, and I). The Na 3 MX 6 structures depend on the types and sizes of M and X: Na 3 MCl 6 and Na 3 MBr 6 prefer the $P\bar{3}$1c, P2 1 /n and $R\bar{3}$ phases, whereas Na 3 MI 6 prefers the C2/m phase. The Na 3 MI 6 C2/m phase is found to exhibit reasonably high ionic conductivity (~10 -4 S/cm -1 ) and anion mixing with Br further improve Na-ion migration, leading to an even higher ionic conductivity (~10 -3 S/cm -1 ) for Na 3 MBr 3 I 3 . The material design principles in this study provide fundamental guidelines for the development of superionic Na halide SEs for high-voltage Na ASSBs

25 ENERGY STORAGE↗
DOE OSTI2022

Cylindrical C 96 Fullertubes: A Highly Active Metal-Free O 2 -Reduction Electrocatalyst

A new isolation protocol was recently reported for highly purified metallic Fullertubes D 5h -C 90 , D 3d -C 96 , and D 5d -C 100 , which exhibit unique electronic features. Here, we report the oxygen reduction electrocatalytic behavior of C 60 , C 70 (spheroidal fullerenes), and C 90 , C 96 , and C 100 (tubular fullerenes) using a combination of experimental and theoretical approaches. C 96 (a metal-free catalyst) displayed remarkable oxygen reduction reaction (ORR) activity, with an onset potential of 0.85 V and a halfway potential of 0.75 V, which are close to the state-of-the-art Pt/C benchmark catalyst values. Here we achieved an excellent power density of 0.75 W cm −2 using C 96 as a modified cathode in a proton-exchange membrane fuel cell, comparable to other recently reported efficient metal-free catalysts. Combined band structure (experimentally calculated) and free-energy (DFT) investigations show that both favorable energy-level alignment active catalytic sites on the carbon cage are responsible for the superior activity of C 96 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Exploring the potential and impact of single-crystal active materials on dry-processed electrodes for high-performance lithium-ion batteries

Roll-to-roll powder-to-film dry processing (DP) and single-crystal (SC) active materials (AMs) with many advantages are two hot topics of lithium-ion batteries (LIBs). However, DP of SC AMs for LIBs is rarely reported. Consequently, the impact of SC AMs on dry-processed LIBs is not well understood. Herein, for the first time, via a set of experimental and theoretical studies of the conventional polycrystalline-AM- and SC-AM-based DPed electrodes (DPEs), this work not only reports a high-performance dry SC-AM cathode for LIB manufacturing, but also establishes some fundamental understanding of SC-based dry-processed electrodes, including their morphology, structure, mechanical strength, electronic conductivity and LIB electrochemical behavior. Further, the results suggest that DP of SC AMs is promising, which can dramatically improve the electrochemical kinetics at electrode level and particle level. Specifically, for the rate capability and long-term cyclability in full cells, SC DPEs exhibit a discharge specific capacity of 152.1 mAh g -1 at 1C and a capacity retention rate of 79.9 % at C/3 over 500 cycles, which are superior to those of PC DPEs (135.6 mAh g -1 and 68.3 %) at the same conditions and are further confirmed by the simulation data from the theoretical modelling study. Therefore, this comprehensive work marks a significant milestone for DP strategy and SC AMs, enlightening future research and development of LIB manufacturing.

25 ENERGY STORAGE↗