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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Surface and Bulk Stabilization of Silicon Anodes with Mixed-Multivalent Additives: Ca(TFSI) 2 and Mg(TFSI) 2

Here, silicon is drawing attention as the upcoming anode material for the next generation of lithium-ion batteries due to its higher capacity compared to commercial graphite. However, silicon anions formed during lithiation are highly reactive with binder and electrolyte components creating an unstable SEI layer and limiting the calendar life of silicon anodes. The reactivity of lithium silicide and the formation of an unstable SEI layer is mitigated by utilizing the use of a mixture of Ca and Mg multivalent cations as an electrolyte additive for Si anodes to improve their calendar life. The effect of mixed salts on the bulk and surface of silicon anodes was studied by multiple structural characterization techniques. Ca and Mg ions in the electrolyte formed relatively thermodynamically stable quaternary Li-Ca-Mg-Si Zintl phases in an in-situ fashion and more stable and denser SEI layer on the Si particles. These in turn protect silicon particles against side reactions with electrolytes in a coin cell. The full cell with the mixed cation electrolyte demonstrates enhanced calendar life performance with lower measured current and current leakage than that of the baseline electrolyte due to reduced side reactions. Electron Microscopy, HRXRD, and solid-state NMR results showed that electrodes with mixed cations tended to have less cracking on the electrode surface compared to Si electrodes with Gen2 + FEC and the presence of mixed cations enhances cation migration and formation of quaternary Zintl phases stabilizing bulk and forming a more stable SEI.

25 ENERGY STORAGE↗
DOE OSTI2022

Exploring the Promise of Multifunctional “Zintl-Phase-Forming” Electrolytes for Si-Based Full Cells

Li-M-Si ternary Zintl phases have gained attention recently due to their high structural stability, which can improve the cycling stability compared to a bulk Si electrode. Adding multivalent cation salts (such as Mg 2+ and Ca 2+ ) in the electrolyte was proven to be a simple way to form Li-M-Si ternary phases in situ in Si-based Li-ion cells. To explore the promise of Zintl-phaseforming electrolytes, we systematically investigated their application in pouch cells via electrochemical and multiscale postmortem analysis. The introduction of multivalent cations, such as Mg 2+ , during charging can form Li x M y Si ternary phases. They can stabilize Si anions and reduce side reactions with electrolyte, improving the bulk stability. More importantly, Mg 2+ and Ca 2+ incorporate into interfacial side reactions and generate inorganic-rich solid- electrolyte interphase, thus enhancing the interfacial stability. Therefore, the full cells with Zintl-phase-forming electrolytes achieve higher capacity retentions at the C/3 rate after 100 cycles, compared to a baseline electrolyte. Additionally, strategies for mitigating the electrode-level fractures of Si were evaluated to make the best use of Zintl-phase-forming electrolytes. In conclusion, this work highlights the significance of synergistic impact of multifunctional additives to stabilize both bulk and interface chemistry in high-energy Si anode materials for Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Polycarbonate‐Based Solid‐Polymer Electrolytes for Solid‐State Sodium Batteries

Solid-polymer electrolytes comprised of polypropylene carbonate (PPC) and varied sodium bis(fluorosulfonyl)imide (NaFSI) salt concentrations are investigated for implementation as a conductive solid polymer electrolyte into solid-state cathode composites utilizing a sodium-layered oxide active material. The ionic conductivity generally increases with NaFSI salt content, reaching ≈1 mS cm −1 at 80 °C at the highest salt concentration (PPC:NaFSI = 0.5:1). Through an all-in-one slurry casting method, Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode composites are fabricated in which the dispersed PPC electrolyte acts as the primary binder. Enabled by a bilayer polymer electrolyte system, cycling performance with the PPC cathode electrolyte is optimized with respect to salt concentration and anode material. The best cyclability is achieved with a moderate salt concentration electrolyte (PPC:NaFSI = 5:1), showcasing an initial capacity of 83 mA h g −1 with a remarkable 80% capacity retention after 150 cycles at C/5 rate and 60 °C. The superior performance of the lower salt concentration electrolyte is attributed to better electrochemical stability, as confirmed by linear sweep voltammetry and online electrochemical mass spectrometry measurements. In conclusion, these results underscore the potential of carbonate-based polymer electrolytes and the importance of balancing electrolyte conductivity and stability in cell design.

25 ENERGY STORAGE↗
DOE OSTI2021

New Insights into the High‐Performance Black Phosphorus Anode for Lithium‐Ion Batteries

Abstract Black phosphorus (BP) is a promising anode material in lithium‐ion batteries (LIBs) owing to its high electrical conductivity and capacity. However, the huge volume change of BP during cycling induces rapid capacity fading. In addition, the unclear electrochemical mechanism of BP hinders the development of rational designs and preparation of high‐performance BP‐based anodes. Here, a high‐performance nanostructured BP–graphite–carbon nanotubes composite (BP/G/CNTs) synthesized using ball‐milling method is reported. The BP/G/CNTs anode delivers a high initial capacity of 1375 mA h g −1 at 0.15 A g −1 and maintains 1031.7 mA h g −1 after 450 cycles. Excellent high‐rate performance is demonstrated with a capacity of 508.1 mA h g −1 after 3000 cycles at 2 A g −1 . Moreover, for the first time, direct evidence is provided experimentally to present the electrochemical mechanism of BP anodes with three‐step lithiation and delithiation using ex situ X‐ray diffraction (XRD), ex situ X‐ray absorption spectroscopy (XAS), ex situ X‐ray emission spectroscopy, operando XRD, and operando XAS, which reveal the formation of Li 3 P 7 , LiP, and Li 3 P. Furthermore, the study indicates an open‐circuit relaxation effect of the electrode with ex situ and operando XAS analyses.

Li, Minsi↗
DOE OSTI2022

Performance of Lithium-Ion Batteries with 3D Printed Anodes and Compressible Carbon Structures

Carbon scaffolds have been shown to improve the performance of Li metal anodes in Li-ion batteries by acting as conductive hosts for Li metal plating and stripping. The scaffolds provide a more uniform electric field, and their 3D geometry enables smaller diffusion paths for the Li ions. In this project, several different types of carbon lattices were 3D printed, mechanically tested, and analyzed in coin cells. Planar and 3D printed graphite coatings were evaluated as the baseline, since graphite is a common anode material. The results showed that implementing a 3D graphite lattice into a coin cell improved the Li plating and stripping efficiency compared to the planar coating. However, since graphite can intercalate Li ions, other carbon materials were also explored that should act as better hosts for Li plating/stripping. To improve the compressibility of these non-graphite carbon scaffolds, five different carbon ink formulations were 3D printed in lattice configurations. SEM imaging and compression testing showed that both the final dimensions and the compressibility of the carbon lattices depended on the type of carbon precursors used. The two most suitable compositions were found to be those made with graphene oxide-resorcinol formaldehyde and graphene oxide-ammonium hydroxide. In the future, these formulations will be further refined to increase their mechanical strength, and their performance as scaffold hosts for Li metal anodes will be evaluated in coin cells.

25 ENERGY STORAGE↗
DOE OSTI2020

Engineering Surface Oxygenated Functionalities on Commercial Carbon toward Ultrafast Sodium Storage in Ether-Based Electrolytes

The pursuit of a high-capacity anode material has been urgently required for commercializing sodium-ion batteries with a high energy density and an improved working safety. In the absence of thermodynamically stable sodium intercalated compounds with graphite, constructing nanostructures with expanded interlayer distances is still the mainstream option for developing high-performance carbonaceous anodes. In this regard, a surface-functionalized and pore-forming strategy through a facile CO 2 thermal etching route was rationally adopted to engineer negligible oxygenated functionalities on commercial carbon for boosting the sodium storage process. Benefitted from the abundant ionic/electronic pathways and more active reaction sites in the microporous structure with noticeable pseudocapacitive behaviors, the functionalized porous carbon could achieve a highly reversible capacity of 505 mA h g -1 at 50 mA g -1 , an excellent rate performance of 181 mA h g -1 at 16,000 mA g -1 , and an exceptional rate cycle stability of 176 mA h g -1 at 3200 mA g -1 over 1000 cycles. These outstanding electrochemical properties should be ascribed to a synergistic mechanism, fully utilizing the graphitic and amorphous structures for synchronous intercalations of sodium ions and solvated sodium ion compounds, respectively. Finally, the controllable generation and evolution of a robust but thin solid electrolyte interphase film with the emergence of obvious capacitive reactions on the defective surface, favoring the rapid migration of sodium ions and solvated species, also contribute to a remarkable electrochemical performance of this porous carbon black.

25 ENERGY STORAGE↗
DOE OSTI2022

Insights into the Effect of Heat Treatment and Carbon Coating on the Electrochemical Behaviors of SiO Anodes for Li-Ion Batteries

The use of SiO as an anode material has attracted significant interest due to its high capacity and long cycling life. Many promising approaches, including structural design and carbon coating at high temperatures, effectively improve its intrinsic low electrical conductivity and poor Coulombic efficiency. However, the “heat treatment process-composition and microstructure-electrochemical properties” relationship of the SiO anode is not fundamentally understood. Here the structure and composition evolution in amorphous SiO and graphene-coated SiO is investigated using different heat-treatment conditions. X-ray absorption near-edge structure techniques are also employed to analyze the surface and bulk composition change during the initial lithiation process, supplemented by physical or chemical characterization and electrochemical testing. Here results reveal the structural transition of SiO during heat treatment, from amorphous to disproportionated hierarchical structure, where the as-formed dielectric exterior SiO 2 shell and interior SiO 2 matrix severely polarizes electrodes, hindering the lithiation process. Carbon coating on SiO effectively restricts the growth of the SiO 2 shell and facilitates charge transfer, leading to improved electrochemical performance. A schematic model is proposed to reveal the relationship between the treatments, the resultant structural evolutions, and corresponding electrochemical behaviors.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Unraveling the Mechanism of Water-Mediated Sulfur Tolerance via Operando Surface-Enhanced Raman Spectroscopy

While several proton-conducting anode materials have shown excellent tolerance to sulfur poisoning, the mechanism is still unclear due largely to the inability to probe miniscule amounts of sulfur-containing species using conventional surface characterization techniques. Here we present our findings in unraveling the mechanism of water-mediated sulfur tolerance of a proton conductor under operating conditions empowered by surface-sensitive, operando surface-enhanced Raman spectroscopy (SERS) coupled with impedance spectroscopy. Contrary to the conventional view that surface-adsorbed sulfur is removed mainly by oxygen anions, it is found that –SO 4 groups on the surface of the proton conductor are converted to SO 2 by a water-mediated process, as confirmed by operando SERS analysis and density functional theory (DFT)-based calculations. Furthermore, the combination of operando SERS performed on a model electrode and theoretical computation offers an effective approach to investigate into complex mechanisms of electrode processes in various electrochemical systems, providing information vital to achieve the rational design of better electrode materials.

25 ENERGY STORAGE↗
DOE OSTI2021

Systematic Evaluation of Carbon Hosts for High-Energy Rechargeable Lithium-Metal Batteries

Rechargeable lithium batteries (RLBs) have attracted wide attention for achieving high energy and low cost, but the poor stability of the Li anode has remained as a large challenge. In the last several years, great efforts have been made to develop carbon anode structures for RLB applications. A wide range of carbon structures as well as many chemical modification strategies have been investigated to improve the Coulombic efficiency and extend the cycle life of the anodes or the cells. However, currently there is no clear conclusion on key factors that determine the performance of such the types of carbon structures due to the wide range of experimental conditions used in such studies. In this study, we systematically evaluated and compared the electrochemical properties of representative carbon anode materials as well as chemically functionalized carbon materials in different electrolytes. We have found that chemical functionalization, metallic loading, and the types of micro or nano-structures all have an effect on Li deposition/stripping process, but by far the most critical factor is the nature of the electrolytes. All carbon materials produced poor Coulombic efficiency and cycle life in conventional carbonate or ether-based electrolytes. However, when a Li metal compatible is used, the average Coulombic efficiency of Li metal deposition on all carbon structures is increased to 99% or higher. This study provides critical lessons on the directions for carbon anodes for RLBs. Based on these findings, we constructed Li metal coin cells using prelithiated hard carbon, LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode, and compatible electrolyte and tested the cells under conditions of lean electrolyte, lean Li metal and high cathode loading required for more than 300 Wh kg-1 specific energy. More than 200 stable cycles were demonstrated with over 80% capacity retention. Furthermore, the existing challenges and potential approaches have been discussed to further extend the cyclability of lithium-metal batteries under practical conditions.

Liu, Yao↗
DOE OSTI2021

Engineering the Si Anode Interface via Particle Surface Modification: Embedded Organic Carbonates Lead to Enhanced Performance

Si nanoparticles (SiNPs) are recognized as a promising anode material for next-generation high-energy lithium-ion batteries. However, due to the more stringent requirements resulting from severe volume change, the solid-electrolyte interphase (SEI) on SiNPs plays a critical role in determining their cycling performance. Engineering the interface for higher stability has become an effective yet challenging approach to accommodate the deterioration of the silicon anode from the repeated lithiation/delithiation process. Herein, we report a novel approach of engineering a covalently bonded organic monolayer of ethylene carbonates onto the surface of the SiNPs that can help form a sturdy SEI. Finally, this molecule-level surface modification provides an effective approach to enable high-energy lithium-ion batteries with Si anodes.

25 ENERGY STORAGE↗
DOE OSTI2025

Resistive Switching of Spinel Li 4 Ti 5 O 12 Lithium-Ion Battery Material for Neuromorphic Computing

The rapid rise of AI has exposed significant limitations in conventional Von Neumann computing architecture, particularly in regard to speed and energy efficiency. To address these challenges, researchers are exploring a brain-inspired neuromorphic architecture that mimics biological neural networks, enabling massive parallel processing with reduced power consumption for complex AI computational demands. Recent interest has focused on utilizing battery electrodes and solid electrolyte materials for their resistive switching properties in developing a neuromorphic architecture. These properties are precisely tuned through local- and bulk-level chemical composition modifications via voltage bias stimuli. In this study, we demonstrate fabricating a three-terminal lithium-ion electrochemical transistor based on lithium titanium oxide (Li 4 Ti 5 O 12 ), a popular lithium-ion battery anode material. We deposited and characterized LTO thin films using RF sputtering, demonstrating a 6 orders of magnitude increase in electronic conductivity upon lithiation, with conductivity plateauing after 20% lithiation. Density functional theory calculations revealed transformation from the insulating to conducting state, supported by experimental characterization through X-Ray Photoelectron Spectroscopy (XPS) and Direct Current (DC) polarization analyses. The fabricated transistor consisted of LTO as the channel layer, gold as source/drain terminals, lithium phosphorus oxynitride (LiPON) as the lithium-ion conductor, and copper as the gate terminal. The device exhibited clear hysteresis in transfer characteristics due to lithium insertion/extraction processes. Long-term potentiation (LTP) and long-term depression (LTD) measurements showed an asymmetric ratio of 1.425 and maximum/minimum conductance ratio of 7.83. When implemented in a deep neural network (DNN) for MNIST handwritten digit recognition, the device achieved 92.03% accuracy over 20 training epochs. Detailed transport mechanism analysis revealed the crucial role of oxygen vacancies and interface effects in device operation. Our preliminary findings establish LTO-based lithium-ion electrochemical transistors as promising candidates for energy-efficient neuromorphic computing applications, offering potential solutions to traditional Von Neumann architecture limitations.

25 ENERGY STORAGE↗
DOE OSTI2022

Spontaneous Lithiation of Binary Oxides during Epitaxial Growth on LiCoO 2

Epitaxial growth is a powerful tool for synthesizing heterostructures and integrating multiple functionalities. Interfacial mixing can readily occur at temperatures required for complete film crystallization and can significantly modify the properties of layered structures, particularly for those containing energy storage materials with smaller cations. Here we show a two-step sequence involving the growth of an epitaxial LiCoO 2 cathode layer followed by the deposition of a binary transition metal oxide (WO 3 , TiO 2 , and others) in which controlled lithiation of the binary oxide occurs. Orientation-controlled epitaxial synthesis of the model solid-state-electrolyte Li 2 WO 4 and model anode material Li 4 Ti 5 O 12 occurs as WO 3 and TiO 2 nucleate their respective host lattices and attract Li ions from the underlying cathode. The cathode layer readily provides a tunable amount of Li ions for the controlled lithiation of the subsequent layer. We demonstrate that this approach can be used for energy materials discovery and exploring different combinations of epitaxial interfaces that can serve as well-defined model systems for mechanistic studies of energy storage and conversion processes.

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

Composite Solid Ion Conductor with Engineered Lithium Interface

Successful widespread commercialization of electric vehicles is contingent upon development of safe high energy density batteries capable of long cycle life. Lithium metal affords the highest theoretical capacity (3,860 mAh/g) and lowest electrochemical potential (-3.04V vs SHE), which offers the highest specific energy density of anode materials today. While Li-ion batteries are capable of delivering energy densities of 400-600 Wh/kg, the development of lithium metal batteries such as Li-S and Li-air may boost this number up to 650 and 950 Wh/kg, respectively. However, significant progress towards the passivation of lithium metal must occur before the energy density benefit can be realized. Issues with lithium dendrite formation, anode volume expansion, and continuous solid electrolyte interphase (SEI) build-up often result in significant safety concerns, high cell resistance, and poor cycle life. The intrinsic high reactivity between lithium metal with conventional lithium ion electrolytes (organic carbonate-based solvents) makes it extremely difficult to overcome these problems. In this project, Wildcat performed focused, fundamental research and development on composite polymer/ceramic electrolytes and protected lithium metal anodes to develop an all solid state lithium metal battery targeting the DOE requirements to enable commercialization. Wildcat successfully leveraged its high throughput battery platform and explored a broad composite electrolyte compositional space. Additionally, Wildcat screened large numbers of inorganic and organic coatings for lithium metal protection using in situ liquid methods and translated the best results to all solid cells. The proposed composite polymer/ceramic electrolyte and a protected lithium metal anode enabled a solid-state lithium metal battery. The ultimate targets from this effort will deliver a safe all solid-state lithium metal pouch cell with over 350 Wh/kg and over 1,000 cycles (C/3) with the cost estimate below $100/kWh. During the course of the project, we demonstrated stable cycling of 10’s of cycles with the composite SSE and our protected lithium. The work has continued after the conclusion of the DOE funding, demonstrating further improvements in catholyte composition and thinner composite solid electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2025

Influence of surface chemistry on Li nucleation energetics on graphene-based surfaces

Lithium metal is a promising high-capacity anode material for solid-state batteries, but it typically suffers from poor cyclability. Carbon scaffold hosts have the potential to improve this performance due to their high electronic conductivity and large surface area, which facilitates lithium-ion adsorption and desorption. Scaffold surface chemistry is known to significantly influence performance outcomes, but the details of these interactions are not fully understood. Here, this study employs first-principles simulations to explore lithium transport and nucleation on graphene anodes with various surface chemistries. Using enhanced sampling techniques, ab initio molecular dynamics, and density functional theory calculations, we find that although surface chemistry has a minimal impact on lithium interfacial transport, it influences surface nucleation significantly. Both heteroatom dopants and intrinsic defects lower the nucleation barrier, creating a more favorable environment for lithium nucleation compared to pristine graphene. In addition, our results reveal a complex interplay between surface lithium concentration, lithium transport, and nucleation kinetics. These findings highlight the potential of surface modifications to precisely control nucleation processes on carbon-based anodes and provide design guidance for reducing dendrite formation and improving the cycle life of solid-state batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Voltammetry measurements in lithium chloride-lithium oxide (LiCl–Li 2 O) salt: An evaluation of working electrode materials

Instrumentation to provide process monitoring (PM) and safeguards for the oxide reduction (OR) step in the electrochemical processing of used oxide nuclear fuel is necessary to ensure equipment is operated as declared. Cyclic voltammetry (CV) has been proposed for real-time monitoring of the operation of an OR process for safeguards purposes. In this study, different materials including 316 stainless steel (SS), tantalum (Ta), molybdenum (Mo), tungsten (W), platinum (Pt), and iridium (Ir) were evaluated as potential working electrode (WE) materials based on their chemical inertness, corrosion resistance, and sensitivity in detecting Li 2 O and other chloride salts in the OR electrolyte. Of the electrodes evaluated, 316 SS, Ir, and Pt all performed reasonably well in the LiCl-Li 2 O electrolyte. Here, stainless steel was operated in the cathodic potential and had reasonable corrosion resistance and is relatively inexpensive. Iridium could be operated in both the cathodic and anodic potentials and was the most corrosion resistant of those evaluated. Platinum is limited to the anodic potential range, had reasonable corrosion resistance, and was the most sensitive to Li 2 O concentrations in the salt. In the development of a stand-alone safeguards instrumentation, our recommendation is a CV sensor fitted with both Ir and Pt WEs. The results in this study may also be helpful for anode material selection in other electrometallurgy industries, such as molten salt electrolysis.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗