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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Ultrafast and Highly Reversible Sodium Storage in Zinc-Antimony Intermetallic Nanomaterials

The progress on sodium-ion battery technology faces many grand challenges, one of which is the considerably lower rate of sodium insertion/deinsertion in electrode materials due to the larger size of sodium (Na) ions and complicated redox reactions compared to the lithium-ion systems. Here, it is demonstrated that sodium ions can be reversibly stored in Zn-Sb intermetallic nanowires at speeds that can exceed 295 nm s -1 . Remarkably, these values are one to three orders of magnitude higher than the sodiation rate of other nanowires electrochemically tested with in situ transmission electron micro­scopy. It is found that the nanowires display about 161% volume expansion after the first sodiation and then cycle with an 83% reversible volume expansion. Despite their massive expansion, the nanowires can be cycled without any cracking or facture during the ultrafast sodiation/desodiation process. Additionally, most of the phases involved in the sodiation/desodiation process possess high electrical conductivity. More specifically, the NaZnSb exhibits a layered structure, which provides channels for fast Na + diffusion. This observation indicates that Zn-Sb intermetallic nanomaterials offer great promise as high rate and good cycling stability anodic materials for the next generation of sodium-ion batteries.

Nie, Anmin↗
DOE OSTI2019

Crystallographic-orientation dependent Li ion migration and reactions in layered MoSe 2

The lithium ion migration dynamics and the fast lithiation pathways in electrode materials are quite vital to the rate capability of lithium ion batteries (LIBs). To reveal the relationship between lithiation behavior and crystallographic orientations in layered MoSe 2 , its dynamic electrochemical reactions are investigated with in situ microscopy technique. Here, we report the crystallographic-orientation dependent lithium ion migration and reaction in MoSe 2 , where the preferential lithium-ion migration is observed along the $\langle10\bar{1}0\rangle$ orientations. These oriented-lithiation tips further assisted the surface to interior lithiation of layered MoSe 2 . At the same time, a phase transition from pristine 2H-MoSe 2 to 1T-Li x MoSe 2 and the following conversion reaction with the formation of Li2Se and Mo are observed during the first lithiation process. The lithiation induced stress and orientation-dependent interfacial reaction rate might be the main factor leading to the orientation-dependent lithiation behavior. The experimentally revealed crystallographic-orientation dependent lithium ion migration and reaction in layered MoSe 2 will provide intuitive understanding of the structural evolution during the discharge/charge cycling process, give guidance for the design of anode materials and can broaden the promising application of MoSe 2 in solid electrochemical devices.

Lithium ion battery↗
DOE OSTI2026

High Purity and Reduced Defects Hard Carbon Synthesis for Sodium-Ion Batteries

Hard carbon (HC) is the state-of-the-art anode material for sodium-ion batteries; however, the high-temperature carbonization of precursors (>1100 °C) often introduces inorganic impurities, an issue that remains largely underexplored. Here, we report a simple synthesis strategy for producing high purity HC by carbonizing a cellulose-derived precursor at 1400 °C under a slightly reducing Ar–H2 atmosphere on a graphite substrate, thereby eliminating the aluminum contamination observed during conventional carbonization on an alumina substrate under Ar. In addition, the modified synthetic condition reduces surface defects and the concentration of oxygen-containing functional groups, thereby altering the interphase formation on the HC surface. At a current density of 20 mA g−1, the impurity-rich HC exhibited an initial coulombic efficiency (ICE) of 74.1% and a reversible capacity of 248.8 mAh g−1. In sharp contrast, the high purity HC delivered a significantly improved ICE of 90.1% and a reversible capacity of 345.1 mAh g−1. These results underscore the critical importance of impurity and defect control during HC synthesis and highlight the clear electrochemical advantages of high purity HC with reduced defects for sodium-ion battery anodes.

Harshita, Lohanni↗
DOE OSTI2014

Fe{sub 2}O{sub 3} nanowires on HOPG as precursor of new carbon-based anode for high-capacity lithium ion batteries

Iron Oxides nanostructures are very promising systems for new generation of anode material for Lithium-Ion batteries because of their high capacity associated to their surface area. A core-level photoemission study of Fe{sub 2}O{sub 3} nanowires deposited on highly-oriented pyrolitic graphite (HOPG) under Li exposure is presented. The Fe-2p, Fe-3p, and Li-1s core-level lineshape evolution upon Li exposure in ultra-high-vacuum conditions clearly brings to light the Fe ion reduction from fully trivalent to prevalently divalent at saturation. Furthermore, the graphite substrate allows allocation of a large amount of Li ions surrounding the iron-oxide nanowires, opening a new scenario towards the use of graphene for improving the ionic charge exchange.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Review—The Lithiation/Delithiation Behavior of Si-Based Electrodes: A Connection between Electrochemistry and Mechanics

Silicon is a promising alternative anode material to graphite because of its high gravimetric and volumetric energy densities. However, severe capacity fading is observed in Si electrodes, and it is a result of mechanical changes of Si, such as volume changes, stress or fracture. Furthermore, these mechanical behaviors are strongly coupled with the electrochemistry of the Li-Si alloying reaction in Si-based electrodes, including both thermodynamics and kinetics. Therefore, the electrochemical properties of Si-based electrodes are strongly dependent on the control of the mechanics of Si during lithiation/delithiation. As such, it is very important to understand the correlation between electrochemistry and mechanics. Here, we review lithiation/delithiation behaviors of various types of Si-based electrodes, applying a fundamental understanding of electrochemistry and mechanics and the correlation between them.

25 ENERGY STORAGE↗
DOE OSTI2014

Reduction Mechanism of Fluoroethylene Carbonate for Stable Solid–Electrolyte Interphase Film on Silicon Anode

Fluoroethylene Carbonate (FEC) is an effective electrolyte additive which can significantly improve the cyclability of Si and other anode materials. However, the fundamental mechanism on this improvement is still not well understood. Based on the results obtained from 6Li Nuclear Magnetic Resonance and X-ray Photoelectron Scanning study, we propose a molecular level mechanism on how FEC affects the formation of solid electrolyte interphase (SEI) film: 1) FEC is reduced through the opening of the five member ring leading to the formation of lithium poly (vinyl carbonate), LiF and some dimmers; 2) The high tensile strength of the FEC-derived lithium poly (vinyl carbonate) enhances the stability of the SEI film. This mechanism has been verified by the results of electrochemical tests.

Environmental Molecular Sciences Laboratory↗
NASA NTRS1994

(abstract) Studies on AB(sub 5) Metal Hydride Alloys with Sn Additives

The use of metal hydrides as negative electrodes in alkaline rechargeable cells is becoming increasingly popular, due to several advantages offered by the metal hydrides over conventional anode materials (such as Zn, Cd) in terms of specific energy environmental cycle life and compatibility. Besides, the similarities in the cell voltage pressure characteristics, and charge control methods of the Ni-MH cells to the commonly used Ni-Cd point to a projected take over of 25% of the Ni-Cd market for consumer electronics by the Ni-MH cells in the next couple of years. Two classes of metal hydrides alloys based on rare earth metals (AB(sub 5)) and titanium (AB(sub 2)) are being currently developed at various laboratories. AB(sub 2) alloys exhibit higher specific energy than the AB(sub 5) alloys but the state of the art commercial Ni-MH cells are predominately manufactured using AB(sub 5) alloys.

earth metals↗
DOE OSTI2020

Ultra-efficient polymer binder for silicon anode in high-capacity lithium-ion batteries

As a highly promising anode material for high-capacity lithium-ion batteries (LIBs), the low electronic conductivity and large volume variation of silicon (Si) make the slurry-coating Si based electrode requiring high content of “inert” materials and suffering rapid capacity fading. In this work, a polyimine, synthesized via one-step condensation reaction, has been demonstrated as an ultra-efficient polymer binder that can resolve the above issues. The polyimine binder containing Si electrode delivers superior electrochemical performance: a delithiation specific capacity of 804.4 mAh g –1 with capacity retention of 82.4% after 1000 cycles at the current density of 2 A g –1 . The high efficiency of polyimine binder for Si electrode has also been demonstrated with ultrahigh weight ratio of “active” material to “inert” material (R A/I ). The electrode with 95 wt% of Si (95Si/Polyimine, R A/I = 19) reveals a reversible delithiation capacity of 2114 mAh g –1 (capacity retention ~ 80.4%) over 200 cycles at the current density of 400 mA g –1 . Even at the high current density of 2 A g –1 , a delithiation capacity of 1087.8 mAh g –1 after 500 cycles can be obtained. Molecular simulations and atomic force microscopy (AFM) indentation are utilized to investigate the ultra-efficiency of polyimine binder. With simple manufacturing process and ultra-efficient binder performance, the designed polyimine binder will be definitely meaningful in achieving low-cost and high-capacity LIBs with prolonged cycle life.

25 ENERGY STORAGE↗
DOE OSTI2019

Encapsulating phosphorus inside carbon nanotubes via a solution approach for advanced lithium ion host

Conventional phosphorus anode materials in lithium/sodium-ion batteries are mainly based on the physical mixing and evaporation/condensation, in which external phosphorus on conductive matrix is unavoidable and hard to be removed due to the formation of crystalline phase. It has been found to break off from conductive matrix easily and deteriorate capacity rapidly. In this communication, we first report a solution processed encapsulation method which facilitates phosphorus anchored inside multi-walled carbon nanotubes (MWCNTs). Any possible external phosphorus adsorbents are hard to transform into crystalline and enable an easy removal by polar solvents. Eventually, the phosphorus rings and chains are successfully encapsulated only inside MWCNTs, exhibiting high cycling stability in lithium-ion battery because of the efficient physical confinement and unique discrete phosphorus segment assemblies inside MWCNTs which ensured enough vacant space for volume expansion.

25 ENERGY STORAGE↗
DOE OSTI2020

Microclusters of Kinked Silicon Nanowires Synthesized by a Recyclable Iodide Process for High-Performance Lithium-Ion Battery Anodes

Silicon shows great promise as a high-capacity anode material for lithium-ion batteries. Nanostructuring silicon minimizes the impact of fracturing during charging and discharging. However, synthesizing nanostructured silicon typically requires complicated procedures with high manufacturing costs. Additionally, these complicated procedures typically have poor secondary particle formation, a requirement to achieve a high tap density. Here, a cost-effective synthesis procedure which generates nearly ideal secondary particle clusters of nanostructured silicon is developed. The cost-effectiveness is a result of the in operando generation of silicon iodide from iodine gas and low-grade silicon microparticle. Decomposition of silicon iodide into crystalline silicon and iodine gas enables recycling of the iodine gas, allowing for near full reutilization of iodine in the following cycles. Additionally, the optimal nanostructures and microstructures of silicon synthesized by the recyclable iodide decomposition reaction enables 83.6% capacity retention over 1000 cycles. The good performance is a result of well-maintained morphology during cycling, enabling reutilization of the solid electrolyte interphase.

25 ENERGY STORAGE↗
DOE OSTI2020

Highly Reversible Plating/Stripping of Porous Zinc Anodes for Multivalent Zinc Batteries

Zinc continues to garner immense interest due to its versatility as an anode material in several configurations utilizing either alkaline or mild-pH electrolytes. Current research on using mild-pH electrolytes has improved the rechargeability aspect of Zn-based batteries since Zn2+ is solely utilized for plating/stripping of Zn. Several studies have incorporated Zn metal foils, yet, dramatic improvements can be achieved by expressing Zn as a porous structure. Herein, we use a quasi-pulsed electrodeposition process to prepare a conformal Zn coating onto 3D porous copper foam. By tuning the electrodeposition parameters, we achieved an optimal Zn coating that undergoes reversible plating/stripping when tested in symmetric Zn cells, which supported a low overpotential of ~60 mV for up to 100 cycles. We further investigated changes in the surface morphology by studying the Zn surface of both foil and 3D structure using scanning electron microscopy and X-ray micro-computed tomography. Both techniques showed that the Zn foil undergoes dramatic alterations at the surface, which results in inhomogeneous deposition of Zn, whereas the 3D form exhibited minimal changes. Lastly, we paired both Zn foil and 3D Zn with vanadium oxide and demonstrated that the porous structure supports high rate capability and high specific capacity.

25 ENERGY STORAGE↗
DOE OSTI2014

Electrochemical characteristics of plasma-etched black silicon as anodes for Li-ion batteries

Nanostructured silicon as an anode material for Li-ion batteries is produced for the first time by inductively coupled plasma–plasma etching of Si wafers in the black silicon regime. The microscopic structure strongly resembles other types of nanostructured silicon, with a well-arranged nanostructure possessing a sufficient porosity for accommodating large volume expansion. Despite these features, however, a high first-cycle irreversible capacity loss and a poor cycle life are observed. The main reason for these poor features is the formation of a thick solid-electrolyte interphase (SEI) layer related to the surface condition of the pristine nanostructured black silicon (b-Si) electrode. Therefore, the cycle life of the b-Si electrode is heavily influenced by the constant reformation of the SEI layer depending upon the surface composition in spite of the presence of nanostructured Si. In the fast lithiation experiments, the nanostructure region of the b-Si electrode is detached from the Si substrate owing to the kinetics difference between the lithium ion diffusion and the electron injection and phase transformation in the nanostructured Si region. This means that more Si substrate is involved in lithiation at high current rates. It is therefore important to maintain balance in the chemical kinetics during the lithiation of nanostructured Si electrodes with a Si substrate.

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

Deliberate Modification of Fe 3 O 4 Anode Surface Chemistry: Impact on Electrochemistry

Fe 3 O 4 nanoparticles (NPs) with an average size of 8-10 nm have been successfully functionalized with various surface-treatment agents to serve as model systems for probing surface chemistry-dependent electrochemistry of the resulting electrodes. The surface-treatment agents used for the functionalization of Fe 3 O 4 anode materials were systematically varied to include aromatic or aliphatic structures: 4-mercaptobenzoic acid (MBA), benzoic acid (BA), 3-mercaptopropionic acid (MPA), and propionic acid (PA). Both structural and electrochemical characterizations have been used to systematically correlate the electrode functionality with the corresponding surface chemistry. Surface treatment with ligands led to better Fe 3 O 4 dispersion, especially with the aromatic ligands. Electrochemistry was impacted where the PA and BA-treated Fe 3 O 4 systems without the -SH group demonstrated higher rate capability than their thiol-containing counterparts and the pristine Fe 3 O 4 . Specifically, the PA system delivered the highest capacity and cycling stability amongst all samples tested. Notably, the aromatic BA system outperformed the aliphatic PA counterpart during extended cycling under high current density, due to the improved charge transfer and ion transport kinetics as well as better dispersion of Fe 3 O 4 NPs, induced by the conjugated system. Our surface engineering of the Fe 3 O 4 electrode presented herein, highlights the importance of modifying the structure and chemistry of surface-treatment agents as a plausible means of enhancing interfacial charge transfer within metal oxide composite electrodes without hampering the resulting tap density of the resulting electrode.

25 ENERGY STORAGE↗
DOE OSTI2023

Crystallographic Insight of Reduced Lattice Volume Expansion in Mesoporous Cu 2+ -Doped TiNb 2 O 7 Microspheres during Li + Insertion

TiNb 2 O 7 represents a promising anode material for lithium-ion batteries (LIBs), but its practical applications are currently hampered by the non-negligible volumetric expansion and contraction during the charge/discharge process and the sluggish ion/electron kinetics. Here a combination technique is reported by systematically optimizing the porous and spherical morphology, crystal structure, and surface decoration of mesoporous Cu 2+ -doped TiNb 2 O 7 microspheres to enhance the electrochemical Li + storage performance and stability simultaneously. The Cu 2+ dopants preferentially replace Ti 4+ in crystal lattices, which decreases the Li + diffusion barrier and increases the electronic conductivity, as confirmed by density functional theory (DFT) calculation and demonstrated by diverse electrochemical characterizations. The successful Cu 2+ doping significantly reduces the lattice expansion coefficient from 7.26% to 4.61% after Li + insertion along the b-axis of TiNb 2 O 7 , as visualized from in situ and ex situ XRD analysis. The optimal 5% Cu 2+ -doped TiNb 2 O 7 with surface coating of N-doped carbon exhibits significantly enhanced specific capacity and rate and cyclic performances in both half- and full-cell configurations, demonstrating an excellent electrochemical behavior for fast-charging LIB applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Benzene Ring Knitting Achieved by Ambient-Temperature Dehalogenation via Mechanochemical Ullmann-Type Reductive Coupling

The current approaches capable of affording conjugated porous networks (CPNs) still rely on solution-based coupling reactions promoted by noble metal complexes or Lewis acids, on-surface polymerization conducted in ultrahigh-vacuum environment at very high temperatures (>200 °C), or mechanochemical Scholl-type reactions limited to electron-rich substrates. To develop simple and scalable approaches capable of making CPNs under neat and ambient conditions, herein, a novel and complementary method to the current oxidative Scholl coupling processes is demonstrated to afford CPNs via direct aromatic ring knitting promoted by mechanochemical Ullmann-type reactions. The key to this strategy lies in the dehalogenation of aromatic halides in the presence of Mg involving the formation of Grignard reagent intermediates. Products (Ph-CPN-1) obtained via direct C-C bond formation between 1,2,4,5-tetrabromobenzene (TBB) monomer feature high surface areas together with mesoporous architecture. The versatility of this approach is confirmed by the successful construction of various CPNs via knitting of the corresponding aromatic rings (e.g., pyrene and triphenylene), and even highly crystalline graphite product was obtained. The CPNs exhibit good electrochemical performance as the anode material in lithium-ion batteries (LIBs). Overall, this approach expands the frontiers of CPN synthesis and provides new opportunities to their scalable applications.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Rationalization of Diversity in Spinel MgFe 2 O 4 Surfaces

Spinel magnesium ferrite (MgFe 2 O 4 ) is a prospective anode material for lithium ion batteries (LIBs). In this study, using density functional theory the first systematic study of diverse MgFe 2 O 4 surfaces is reported in three types of spinel structures: normal, mixed, inverse, which can have significant impact on the initial lithiation. The results show that the faceting and therefore the shape of MgFe 2 O 4 crystals strongly depend on the bulk structures. Upon going from normal, mixed to inverse spinel, the energetically preferred facets of MgFe 2 O 4 vary from the combination of (1 0 0) and (3 1 1), soly {1 0 0} to a combination of (1 0 0), (0 0 1), (1 1 1), and (3 1 1), respectively, depending on the distribution of Mg 2+ in the spinel structure. However, there is one common descriptor to the stable surfaces among all three MgFe 2 O 4 systems: high density of Mg 2+ exposed to the surface. Finally, this study rationalizes the essential effect of the substitution of Zn 2+ for Mg 2+ in ferrites and provides new insights on how to control the shape of ferrite materials and thus tune the performances of LIBs.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Phosphorus-Graphene Nanosheet Hybrids as Lithium-Ion Anode with Exceptional High-Temperature Cycling Stability

A red phosphorus-graphene nanosheet hybrid is reported as an anode material for lithium-ion batteries. Graphene nanosheets form a sea-like, highly electronically conductive matrix, where the island-like phosphorus particles are dispersed. Benefiting from this structure and properties of phosphorus, the hybrid delivers high initial capacity and exhibits promising retention at 60 °C.

36 MATERIALS SCIENCE↗