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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Improving Cycling Performance of Anode-Free Lithium Batteries by Pressure and Voltage Control

The anode-free lithium (Li) batteries (AFLBs) have great potential to provide higher energy density than most other batteries. However, the performance of AFLBs is very sensitive to pressure and other operating parameters, especially for coin cells widely used in AFLB investigations. Therefore, optimizing cell assembly parameters and test protocol is critical to get reliable and comparable results in this field. In this work, the operating voltage range of AFLBs using a localized high concentration electrolyte has been optimized. The morphology of the deposited Li in AFLBs is much more indicting to the pressure than other type of batteries due to the absence of anode active material (i.e. Li) as a pressure cushion layer in the as prepared cells. With an optimized cycling protocol, a thin layer of uniform nucleation sites can be formed in the initial cycle which will facilitate smooth Li desposition/stripping in the subsequent cycles of AFLBs. The solid electrolyte interphase layer formed under optimized pressure and uniform pressure distribution exhibits a good mechanical stability even after long-term cycling. In conclusion, with an optimized cell configuration, the internal pressure in the coin cells has been optimized to improve the cycling performance of AFLBs (Cu||NMC811) with 72% of capacity retention in 100 cycles.

25 ENERGY STORAGE↗
DOE OSTI2022

Scalable High-H 2 Flux, Robust Thin Film Solid Oxide Electrolyzer

This project was aimed at the development of proton-conducting SOEC (P-SOEC) technology that has the potential to meet key DOE H 2 production targets. A decreased proton resistance of the electrolyte and Faradaic efficiency improvements were sought to increase the fraction of consumed electrolysis power that is used to actually generate H 2 , while simultaneously decreasing cost dramatically. Moreover, the development project was intended to yield maximum durability through the use of a steam protective layer. Furthermore, sputtering was used to overcome processing challenges that have hampered P-SOEC development, while the low-temperature operation goal of 500 °C was expected to aid in mitigating thermally activated long-term degradation. The approach to high-performance, lower-temperature SOECs leveraged our existing SOFC Ni-cermet anode support and extensive thin-film sputtering layer-deposition experience. Rather than an all-in-one, reversible fuel cell approach which has many unacceptable tradeoffs, we focused on the many benefits to hydrogen generating SOECs, including the existence of synergies for reduced manufacturing costs (e.g., SOECs and SOFCs share supporting layers and overall manufacturing processing). The end result of this project was expected to increase current performance at 500 °C from approximately 0.8 A/cm 2 (at 60% Faradaic efficiency) at 1.4 V to > 1 A/cm 2 (at > 95% Faradaic efficiency) with a > 40% reduction in system cost and to enable operation of P-SOECs in steam contents >> 20% for a goal of a > 40,000 hours lifetime. To enable 500 °C operation in a very high steam atmosphere (> 20%), we proposed the use of a sputtered dense thin film (~0.1-1 µm thick) of high-stability Ba(Zr,Y)O 3 (BZY) to protect the Ba(Ce,Zr,Y,Yb)O 3 (BCZYYb) electrolyte. The BZCYYb, in turn, blocks the hole conductivity of the BZY to boost Faradaic efficiency. As FE increases, more of the consumed electricity is used in electrolysis to generate H 2 , rather than being shunted. Additionally, as cell resistance decreases, the voltage required to maintain current decreases, as well as the power required to generate the same amount of H 2 . With the proposed enhancements, these two factors result in the final 46% decrease in power needed to run the system. Likewise, a production rate of 50,000 kg H 2 /day will require 55% less active area, such that a system will need only 650 cells for an 80 cm 2 active area instead of ~1,440. Taking the 2016 DOE projected current cost and modifying the electricity cost and linearly scaling the other costs (except thermal feedstock) based on the cell area improvement, results in a 44% decrease in lifetime system cost, or a decrease from $\$$4.95/kg H 2 to $\$$2.75/kg H 2 . This is well below the 2018 DOE target of $\$$4/kg H 2 . The results from this project showed that we can create a P-SOEC with enhanced steam stability using two different electrolytes (i.e., one on top of the other) and achieve sufficiently low area specific resistance (ASR) to achieve the target performance. Unfortunately, due to extended delays at the beginning of the project and related supply chain and equipment access issues, we were not able to completely show increased Faradaic efficiency for the P-SOEC and therefore were unable to demonstrate the full proof of concept within the first budget period budget. While there are still challenges that remain to be solved, significant progress was made during this project and the concept still has merit that warrants further development.

08 HYDROGEN↗
DOE OSTI2022

Conformal LiF Stabilized Interfaces via Electrochemical Fluorination on High Voltage Spinel Cathodes (≈4.9 V) for Lithium-Ion Batteries

The high voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel is one of the promising cathodes for the lithium-ion batteries due to its high energy densities, good rate performance. However, its high operating potential (≈4.75 V) causes extensive oxidation of conventional carbonate electrolytes, resulting an unstable and thick cathode electrolyte interphase (CEI) layer with a large irreversible capacity and low coulombic efficiency. In this work, we report the formation of thin LiF stabilized interfaces on LNMO via electrochemical fluorination that significantly improves the cycling stability and enhanced the capacity. An electrochemically induced conformal LiF layer acts as a part of a robust CEI by reducing the leakage of electrons and allowing the conduction of Li ions through it. Because of the robust LiF stabilized CEI, LNMO delivers a discharge capacity of ≈148.5 and ≈117.1 mAh g -1 at 0.1 and 1 C rate, respectively. It exhibits excellent cyclability with 80% capacity retention (CR) after 600 cycles in lithium-half cell and ≈90% CR after 200 cycles in full cell with only 0.03% and 0.05% capacity decay per cycle in conventional carbonate electrolytes without additives. Such an excellent electrochemical performance could lead to the potential development of high energy density batteries with high voltage cathodes for grid-based applications.

25 ENERGY STORAGE↗
DOE OSTI2021

Quantifying lithium loss in amorphous silicon thin-film anodes via titration-gas chromatography

Silicon with a high theoretical capacity (3,579 mAh/g) is a promising anode candidate for lithium-ion batteries. However, commercialization is still impeded by low Coulombic efficiency, caused by solid electrolyte interphase (SEI) formation and trapped lithium (Li)-silicon (Si) alloy during repeated volume change. Quantifying capacity losses from each factor is crucial to formulate rational design strategies for further improvement. In this work, titration-gas chromatography and cryogenic transmission electron microscopy are applied to characterize the evolution of trapped Li-Si alloy and SEI growth in a silicon thin-film anode. It is found that continuous growth of the SEI is the dominant factor for lithium inventory loss during cycling, with only a marginal increase in trapped Li-Si alloy. This study offers a quantitative approach to differentiate Li in the SEI from trapped Li in Li-Si alloy through a silicon thin-film anode, providing unique insights into identifying critical bottlenecks for developing Si anodes.

25 ENERGY STORAGE↗
DOE OSTI2021

Probing the Effects of Acid Electrolyte Anions on Electrocatalyst Activity and Selectivity for the Oxygen Reduction Reaction

The local microenvironment at the electrode-electrolyte interface plays an important role in electrocatalytic performance. Herein, we investigate the effect of acid electrolyte anion identity on the oxygen reduction reaction (ORR) activity and selectivity of smooth Ag and Pd catalyst thin films. Cyclic voltammetry in perchloric, nitric, sulfuric, phosphoric, hydrochloric, and hydrobromic acid, at pH1, reveals that Ag ORR activity trends as follows: HClO 4 >HNO 3 >H 2 SO 4 >H 3 PO 4 >HCl>>HBr, while Pd ORR activity trends as: HClO 4 >H 2 SO 4 >HNO 3 >H 3 PO 4 >HCl>>HBr. Moreover, rotating-ring-disk-electrode selectivity measurements demonstrate enhanced 4 e - selectivity on both Ag and Pd, by up to 35% H 2 O 2 and 10% H 2 O 2 respectively, in HNO 3 compared to in HClO 4 . Relating physics-based modeling and experimental results, we postulate that ORR performance depends greatly on anion-related phenomena in the double layer, for instance competitive adsorption and non-covalent interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Dual-Band Electrochromism in Hydrous Tungsten Oxide

The independent modulation of visible and near-infrared light by a single material, termed dualband electrochromism, is highly desirable for smart windows to enhance the energy efficiency of buildings. Tungsten oxides are commercially important electrochromic materials, exhibiting reversible visible and near-infrared absorption when electrochemically reduced in an electrolyte containing small cations or protons. The presence of structural water in tungsten oxides has been associated with faster electrochromic switching speeds. Here, we find that WO 3 ·H 2 O, a crystalline hydrate, exhibits dual-band electrochromism unlike the anhydrous WO 3 providing a heretofore unexplored route to tune the electrochromic response of tungsten oxides. Absorption of near-infrared light is achieved at low Li + /e - injection, followed by the absorption of visible light at higher Li + /e - injection as a result of an electrochemically-induced phase transition. We propose that this dual-band modulation is possible due to the more open structure of WO 3 ·H 2 O as compared to WO 3 . This facilitates a more extended solid solution Li + insertion regime that benefits the modulation of near-infrared radiation via plasmon absorption. Higher degrees of Li + /e - insertion lead to polaronic absorption associated with localized charge storage. Furthermore, these results inform how structural factors influence the electrochemically induced spectral response of transition metal oxides and the important role of structural water beyond optical switching speed.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Lithium-ion electrolytic substrates for sub-1V high-performance transition metal dichalcogenide transistors and amplifiers

Electrostatic gating of two-dimensional (2D) materials with ionic liquids (ILs), leading to the accumulation of high surface charge carrier densities, has been often exploited in 2D devices. However, the intrinsic liquid nature of ILs, their sensitivity to humidity, and the stress induced in frozen liquids inhibit ILs from constituting an ideal platform for electrostatic gating. Here we report a lithium-ion solid electrolyte substrate, demonstrating its application in high-performance back-gated n-type MoS 2 and p-type WSe 2 transistors with sub-threshold values approaching the ideal limit of 60 mV/dec and complementary inverter amplifier gain of 34, the highest among comparable amplifiers. Remarkably, these outstanding values were obtained under 1 V power supply. Microscopic studies of the transistor channel using microwave impedance microscopy reveal a homogeneous channel formation, indicative of a smooth interface between the TMD and underlying electrolytic substrate. These results establish lithium-ion substrates as a promising alternative to ILs for advanced thin-film devices.

42 ENGINEERING↗
DOE OSTI2020

Observation of single-defect memristor in an MoS2 atomic sheet

Non-volatile resistive switching, also known as memristor effect, where an electric field switches the resistance states of a two-terminal device, has emerged as an important concept in the development of high-density information storage, computing and reconfigurable systems. The past decade has witnessed substantial advances in non-volatile resistive switching materials such as metal oxides and solid electrolytes. It was long believed that leakage currents would prevent the observation of this phenomenon for nanometre-thin insulating layers. However, the recent discovery of non-volatile resistive switching in two-dimensional monolayers of transition metal dichalcogenide and hexagonal boron nitride sandwich structures (also known as atomristors) has refuted this belief and added a new materials dimension owing to the benefits of size scaling. Here we elucidate the origin of the switching mechanism in atomic sheets using monolayer MoS 2 as a model system. Atomistic imaging and spectroscopy reveal that metal substitution into a sulfur vacancy results in a non-volatile change in the resistance, which is corroborated by computational studies of defect structures and electronic states. These findings provide an atomistic understanding of non-volatile switching and open a new direction in precision defect engineering, down to a single defect, towards achieving the smallest memristor for applications in ultra-dense memory, neuromorphic computing and radio-frequency communication systems.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Intercalation–exfoliation processes during ionic exchange reactions from sodium lepidocrocite-type titanate toward a proton-based trititanate structure

Topochemical reactions involving ionic exchange have been used to assess a large number of metastable compositions, particularly in layered metal oxides. This method encompasses complex reactions that are poorly explored, yet are of prime importance to understand and control the materials’ properties. In this work, we embark on investigating the reactions involved during the ionic exchange between a layered Na-titanate (lepidocrocite-type structure) and an acidic solution (HCl), leading to a protonic (H 3 O + ) titanate (trititanate structure). The reactions involve an ionic exchange provoking a structural change from the lepidocrocite-type to the trititanate structure as shown by real-space refinements of ex situ pair distribution function data. Mobile Na + ions are exchanged by hydronium ions inducing high proton mobility in the final structure. Moreover, the reaction was followed by ex situ 23 Na and 1 H solid-state MAS NMR which allowed, among other things, confirming that the Na + ions are in the interlayer space and specifying their local environment. Strikingly, the ionic exchange reaction induces progressive exfoliation of the Na-titanate particles leading to 2–5 nm thin elongated crystallites. To further understand the different steps associated with the ionic exchange, the evolution of the electrolytic conductivity, using conductimetric titration, has been monitored upon HCl addition, enabling characterization of the intercalation(H + )/de-intercalation(Na + ) reactions and assessing kinetic parameters. Accordingly, it is hypothesized that the exfoliation of the particles is due to the accumulation of charges at the particle level in relation to the rapid intercalation of protons. This work provides novel insights into ionic exchange reactions involved in layered oxide compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Methods of forming electrode structures

An electrode structure and its method of manufacture are disclosed. The disclosed electrode structures may be manufactured by depositing a first release layer on a first carrier substrate. A first protective layer may be deposited on a surface of the first release layer and a first electroactive material layer may then be deposited on the first protective layer. Subsequently, the first carrier substrate may be delaminated from the first release layer. The first release layer may then be removed from the first protective layer by dissolution in an electrolyte. The first protective layer may have a low mean peak to valley surface roughness and/or may be thin. In some embodiments, an interface between the first protective layer and the first electroactive material layer has a low mean peak to valley surface roughness. In some embodiments, a thickness of the first protective layer is greater than a mean peak to valley roughness of the first release layer. In some embodiments, an adhesive strength between the first release layer and the first protective layer is greater than an adhesive strength between the first release layer and the first carrier substrate.

Mikhaylik, Yuriy V.↗
DOE OSTI2024

A dynamically bare metal interface enables reversible magnesium electrodeposition at 50 mAh cm −2

Understanding and facilitating pure magnesium nucleation/growth electrodeposition behavior with ultrahigh Coulombic efficiency is complicated by the phenomenon of solid electrolyte interphase (SEI) formation in state-of-the-art, halogen-free magnesium electrolytes. Defining the electrolyte properties necessary to achieve ideal electrodeposition/stripping (E/S) thus remains elusive. Here, in this work, we reveal for the first time, rapid magnesium electrodeposition behavior that forms densely aligned, micron-sized thin platelets by establishing a dynamic bare magnesium/electrolyte interface during high-rate net plating. This effectively “SEI-free” interface allows facile magnesium diffusion and migration in stripping with near-unity E/S efficiency under demanding conditions over long-term cycling. The intrinsic electrolyte stability of the salt/solvent at the molecular level is the key to forming such an interface. The efficacy of the dynamic bare interface and an electrodeposited, free-standing magnesium anode is demonstrated in a high-areal-capacity full cell. These findings provide new design principles and fundamental understanding of interfacial chemistry in multivalent metal batteries.

Mg full cell↗
DOE OSTI2023

Ultrasmooth Epitaxial Pt Thin Films Grown by Pulsed Laser Deposition

Platinum (Pt) thin films are useful in applications requiring high-conductivity electrodes with excellent thermal and chemical stability. Ultrasmooth and epitaxial Pt thin films with single-crystalline domains have the added benefit of providing ideal templates for the subsequent growth of heteroepitaxial structures. Here, we grow epitaxial Pt (111) electrodes (ca. 30 nm thick) on sapphire (α-Al 2 O 3 (0001)) substrates with pulsed laser deposition. This versatile technique allows control of the growth process and fabrication of films with carefully tailored parameters. X-ray scattering, atomic-force microscopy, and electron microscopy provide structural characterization of the films. Various gaseous atmospheres and temperatures were explored to achieve epitaxial growth of films with low roughness. A two-step (500 °C/300 °C) growth process was developed, yielding films with improved epitaxy without compromising roughness. The resulting films possess ultrasmooth interfaces (<3 Å) and high electrical conductivity (6.9 × 10 6 S/m). Finally, Pt films were used as current collectors and templates to grow lithium manganese oxide (LiMn 2 O 4 (111)) epitaxial thin films, a cathode material used in Li-ion batteries. In conclusion, using a solid-state ionogel electrolyte, the films were highly stable when electrochemically cycled in the 3.5-4.3 V vs Li/Li + range.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Electrodeposition method development for Californium Rare Isotope Breeder Upgrade (CARIBU) Source

Electrodeposition is one of the most widely utilized techniques for thin-film production with high yields. Although it is used extensively, this technique still presents several issues limiting its usefulness, including excess thickness and frequent cracking of deposited films. Efforts to improve thin-film production recently undertaken at Oak Ridge Laboratory by the authors have included studying operating conditions and applied electrolytes. Samarium was used as a surrogate material for californium, and yield was compared with different deposition condition. The final procedure from the optimized condition will be applied during production of the californium-252 source for the Californium Rare Isotope Breeder Upgrade (CARIBU) project, and the fission fragment will be analyzed.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Femtosecond Laser Additive Manufacturing of Multi-Material Layered Structures

Laser additive manufacturing (LAM) of a multi-material multi-layer structure was investigated using femtosecond fiber lasers. A thin layer of yttria-stabilized zirconia (YSZ) and a Ni–YSZ layer were additively manufactured to form the electrolyte and anode support of a solid oxide fuel cell (SOFC). A lanthanum strontium manganite (LSM) layer was then added to form a basic three layer cell. This single step process eliminates the need for binders and post treatment. Parameters including laser power, scan speed, scan pattern, and hatching space were systematically evaluated to obtain optimal density and porosity. This is the first report to build a complete and functional fuel cell by using the LAM approach.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Influence of Water Sorption on Ionic Conductivity in Polyether Electrolytes at Low Hydration

Ion-containing polymers are subject to a wide range of hydration conditions across electrochemical and water treatment applications. Significant work on dry polymer electrolytes for batteries and highly swollen membranes for water purification has informed our understanding of ion transport under extreme conditions. However, knowledge of intermediate conditions (i.e., low hydration) is essential to emerging applications (e.g., electrolyzers, fuel cells, and lithium extraction). Ion transport under low levels of hydration is distinct from the extreme conditions typically investigated, and the relevant physics cannot be extrapolated from existing knowledge, stifling materials design. In this study, we conducted ion transport measurements in LiTFSI-doped polyethers that were systematically hydrated from dry conditions. A semiautomated apparatus that performs parallel measurements of water uptake and ionic conductivity in thin-film polymers under controlled humidity was developed. For the materials and swelling range considered in this study (i.e., <0.07 g water/g dry polymer electrolyte), ionic conductivity depends nonlinearly on water uptake, with the initial sorbed water weakly affecting conductivity. With additional increases in swelling, more significant increases in conductivity were observed. Remarkably, changes in conductivity induced by water sorption were correlated with the number of water molecules per lithium ion, with the normalized molar conductivity of different samples effectively collapsing onto one another until this unit of hydration exceeded the solvation number of lithium ions under aqueous conditions. Furthermore, these results provide important knowledge regarding the effects of trace water contamination on conductivity measurements in polymer electrolytes and demonstrate that the lithium-ion solvation number marks a key transition point regarding the influence of water on ion transport in ion-containing polymers.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Orientation microscopy–assisted grain boundary analysis for protonic ceramic cell electrolytes

Abstract Grain boundaries in protonic ceramic cell (PCC) electrolytes hinder proton transport, reducing interfacial conductivity. In multicomponent PCC electrolytes, the inclusion of sintering aids further accentuates the complexity of grain boundaries. In this study, we synthesize nanocrystalline BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3− δ thin films via pulsed laser deposition and analyze their grain boundary character distributions using orientation data collected by precession electron diffraction technique. The results reveal an anisotropic distribution of grain boundary characters, with notably high populations of 180°‐tilt and twist grain boundaries. These findings provide critical insights into identifying the predominant grain boundaries in this PCC electrolyte material, assessing the vast five‐dimensional grain boundary space.

Patel, Sooraj [School of Aerospace and Mechanical ↗
DOE OSTI2021

Nanocolumnar Pt:Ni Alloy Thin Films by High Pressure Sputtering for Oxygen Reduction Reaction

Self-supported nanocolumnar Pt:Ni thin films (TFs) with varying Pt:Ni atomic ratios and Pt mass loadings were produced on a microporous layer (MPL)-like surface composed of carbon particles by high pressure sputtering and examined as oxygen reduction reaction (ORR) electrocatalysts for polymer electrolyte membrane fuel cells. Cauliflower-like microstructures were observed from scanning electron microscopy imaging. Various Pt:Ni atomic ratios were obtained by simply changing the relative deposition power between Pt and Ni source and investigated by X-ray diffraction and quartz crystal microbalance analysis. Additionally, electrochemical characterization of the Pt:Ni-TF/MPL-like-layer/glassy-carbon samples was conducted through benchtop cyclic voltammetry and rotating disk electrode measurements. The electrochemically active surface area (ECSA) was found to be between 22–42 m 2 g -1 for different Pt:Ni atomic ratios. Lower Pt mass loadings exhibited a higher ECSA and the catalytic activity of all Pt:Ni ratios increased with the increase in Pt mass loading. The ORR activity of the Pt:Ni-TFs increased in the order of 3:1 < 1:1 < 1:3 with exhibiting a specific activity of 1781 μA cm -2 and mass activity of 0.66 A mg -1 for the Ni-rich film with 1:3 ratio. The catalytic performance of Pt:Ni-TFs were higher than traditional high surface area carbon supported Pt nanoparticles, elemental Pt nanorods, and Pt-Ni nanorods.

08 HYDROGEN↗
DOE OSTI2024

Durability enhancement of all-solid-state electrochromic devices by adjusting the charge density ratio between electrochromic and counter electrode layers

Here, owing to an increase in global warming, smart-window devices based on charge-balanced electrochromic devices (ECDs), which exhibit high potential to increase the thermal efficiency of buildings, have gained prominence. However, studies on the fabrication and cycling stability of charge-balanced ECDs are scarce. In this study, WO 3 and NiO x films were deposited on indium-tin-oxide (ITO)-coated glass substrates by reactive direct-current magnetron sputtering, and the deposition time was varied to control the thickness and charge density of the thin films. Subsequently, the NiO x /ITO/glass and WO 3 /ITO/glass substrates were laminated with a Li-based polymeric electrolyte to fabricate all-solid-state ECDs comprising electrochromic (EC) and counter-electrode (CE) layers in charge-density ratios of 12.6, 6.4, 2.3, and 1.1. Changes in the electrochromic properties, device-layer microstructure, crystal structure, and elemental composition of the as-constructed ECDs before and after degradation were investigated to understand the influence of the charge-density ratio of the EC and CE layers on the long-term durability of ECDs. Increasing the charge-density ratio decreased the cycling stability of the device owing to changes in the microstructure and crystal structure of the NiO x layer in the microstructural deep-trap sites. Among all the ECDs, those comprising EC and CE layers with similar charge densities showed the most stable optical modulation and highest long-term durability. Finally, based on the aforementioned results, a degradation mechanism for charge-imbalanced all-solid-state ECDs was proposed. This study is expected to open new frontiers in designing optimal-performance electrochemical devices with a wide variety of potential applications.

14 SOLAR ENERGY↗