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Veith, Gabriel M

Publications and source records attributed to Veith, Gabriel M.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Impact of Lithium‐Free Borate Additives on the Cycle Life and Calendar Aging of Silicon‐Based Lithium‐Ion Batteries

Silicon-anode lithium-ion batteries (LIBs) suffer from limited cycle life and poor calendar life, constraining their large-scale commercialization. Integrating additives into electrolytes is a simple and cost-effective strategy to improve these aspects. The effects of lithium-free boron-based additives on cycling and calendar performance of high-loading Si-anode LIBs remain largely unexplored. In this work, the influence of five Li-free borate additives, each with distinct molecular structures and elemental compositions, is systematically investigated. All additives enhance cycle life to varying extents. Notably, the addition of 1 v/v% tri(2,2,2-trifluoroethyl) borate to the baseline electrolyte nearly doubles the cycle life at 50% state of health. This enhancement is attributed to three key factors. Specifically, borate additives 1) improve electrochemical activity, 2) act as anion receptors that interact with [PF6]- anions and carbonate solvents to reduce electrolyte decomposition, and 3) promote the formation of a stable and polymeric solid electrolyte interphase layer. Furthermore, these additives exhibited negligible impact in mitigating leakage current during a 180 h voltage-hold calendar-aging test, indicating their limited effect in calendar life. These findings provide insight into the role of Li-free borate additives in improving cycle life while addressing the knowledge gap regarding their influence on calendar aging.

Li, Defu↗
DOE OSTI2015

PdHx entrapped in covalent triazine framework modulates selectivity in glycerol oxidation [Modulation of palladium activity and stability by a covalent triazine framework]

The confinement of a Pd nanoparticle within a nitrogen-containing covalent triazine framework (CTF) material was investigated to understand if the highly tunable CTF chemistry mediates the Pd catalytic properties through an ensemble effect with the CTF nitrogen atoms or a confinement effect within the CTF pores. The results surprisingly demonstrate that the CTF stabilizes the formation of 2.6 nm PdHx particles within the pores. These PdHx particles are very active for the liquid phase oxidation of glycerol due to the in situ formation of H2O2 which catalytically promotes the initial C-C cleavage. In addition the confined particles are stable over many catalytic cycles whereas nanoparticles trapped outside of the pores loose activity rapidly. These results indicate that there is the potential to tune the CTF chemistry to significantly modify the chemistry of the catalytic metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Superior Conductive Solid-like Electrolytes: Nanoconfining Liquids within the Hollow Structures

The growth and proliferation of lithium (Li) dendrites during cell recharge is unavoidable, which seriously hinders the development and application of rechargeable Li metal batteries. Solid electrolytes with robust mechanical modulus are regarded as a promising approach to overcome the dendrite problems. However, their room-temperature ionic conductivities are usually too low to reach the level required for normal battery operation. Here, a class of novel solid electrolytes with liquid-like room-temperature ionic conductivities (> 1 mS cm-1) has been successfully synthesized by taking advantage of the unique nanoarchitectures of hollow silica (HS) spheres to confine liquid electrolytes in hollow space to afford high conductivities. In a symmetric lithium/lithium cell, such kind of solid-like electrolytes demonstrates a robust performance against Li dendrite problems, well stabilizing the cell system from short circuiting in a long-time operation at current densities ranging from 0.16 to 0.32 mA cm-2. Moreover, the high flexibility and compatibility of HS nanoarchitectures, in principle, enables broad tunability to choose desired liquids for the fabrication of other kinds of solid-like electrolytes, such as those containing Na+, Mg2+ or Al3+ as conductive media, providing a useful alternative strategy for the development of next generation rechargeable batteries.

hollow nanoarchitecture↗
DOE OSTI2014

Gold nanocatalysts supported on heterostructured PbSO4-MCF mesoporous materials for CO oxidation

Metal oxides are commonly used as the supports of gold nanoparticles for catalytic CO oxidation, whereas metal salts are rarely considered suitable supports. In the present work, we developed a new kind of gold nanocatalyst supported on heterostructured PbSO4-MCF mesoporous materials that was prepared by an in situ growth method using dodecylbenzenesulfonate (SOBS) as a sulfonate precursor. It was found that an Au/PbSO4-MCF (SDBS) catalyst preheated at 300 degrees C showed high CO conversion below 100 degrees C. In addition, the stability of selected catalysts was studied as a function of time on stream. Because of the alteration of surface properties, these Au nanocatalysts were highly sinter-resistant. Published by Elsevier B.V.

Li, Lin↗
DOE OSTI2014

Sodium manganese oxide thin films as cathodes for Na-ion batteries

This paper presents the fabrication and characterization of sodium manganese oxide cathode thin films for rechargeable Na-ion batteries. Layered oxide compounds of nominal compositions Na0.6MnO2 and Na1.0MnO2 have been prepared by radio frequency magnetron sputtering and post-annealing at high temperatures under various conditions. The Na0.6MnO2 thin films possess either a hexagonal or orthorhombic structure while the Na1.0MnO2 films crystallize in a monoclinic structure, as shown by X-ray diffraction and X-ray absorption spectroscopy results. The potential profiles of the film cathodes are characterized by features similar to those measured for the powders and exhibit reversible storage capacities in the range of 50-60 Ah cm-2 m-1, which correspond to about 120-140 mAh g-1, and are maintained over 80 cycles.

Baggetto, Loic↗
DOE OSTI2014

The electrochemical reactions of pure In with Li and Na: anomalous electrolyte decomposition, benefits of FEC additive, phase transitions and electrode performance

Indium thin films are evaluated as an anode material for Li-ion and Na-ion batteries (theoretical capacities of 1012 mAh g-1 for Li and 467 mAh g-1 for Na). The native surface oxides are responsible for the anomalous electrolyte decomposition during the first cycle while oxidized In species are found to be responsible for the electrolyte decomposition during the subsequent cycles. The presence of 5wt% FEC electrolyte additive suppresses the occurrence of the anomalous electrolyte decomposition during the first cycle but is not sufficient to prevent the decomposition upon further cycling from 0 to 2 V. Prevention of the anomalous decomposition can be achieved by restricting the charge cut-off, for instance at 1.1 V, or by using larger amounts of FEC. The In films show moderately good capacity retention with storage capacities when cycled with Li (950 mAh g-1) but significantly less when cycled with Na (125 mAh g-1). XRD data reveal that several known Li-In phases (i.e LiIn, Li3In2, LiIn2 and Li13In3) form during the electrochemical reaction. In contrast, the reaction with Na is severely limited. The largest amount of inserted Na is evidenced for cells short-circuited 40 hrs at 65C, for which the XRD data show the coexistence of NaIn, In, and an unknown phase. During cycling, mechanical degradation due to repeated expansion/shrinkage, evidenced by SEM, coupled with SEI formation is the primary source of the capacity fade. Finally, we show that the In thin films exhibit very high rate capability for both Li (100 C) and Na (30 C).

Hawks, Samantha A↗
DOE OSTI2014

Synthesis and Characterization of Lithium Bis(fluoromalonato)borate (LiBFMB) for Lithium Ion Battery Applications

A new orthochelated salt, lithium bis(monofluoromalonato)borate (LiBFMB), has been synthesized and purified for the first time for application in lithium ion batteries. The presence of fluorine in the borate anion of LiBFMB increases its oxidation potential and also facilitates ion dissociation, as reflected by the ratio of ionic conductivity measured by electrochemical impedance spectroscopy ( exp) and that by ion diffusivity coefficients obtained using pulsed field gradient nuclear magnetic resonance (PFG-NMR) technique ( NMR). Half-cell tests using 5.0 V lithium nickel manganese oxide (LiNi0.5Mn1.5O4) as a cathode and EC/DMC/DEC as a solvent reveals that the impedance of the LiBFMB cell is much larger than those of LiPF6 and LiBOB based cells, which results in lower capacity and poor cycling performance of the former. XPS spectra of the cycled cathode electrode suggest that because of the stability of the LiBFMB salt, the solid electrolyte interphase (SEI) formed on the cathode surface is significantly different from those of LiPF6 and LiBOB based electrolytes, resulting in more solvent decomposition and thicker SEI layer. Initial results also indicate that using high dielectric constant solvent PC alters the surface chemistry, reduces the interfacial impedance, and enhances the performance of LiBFMB based 5.0V cell.

Liao, Chen↗
DOE OSTI2014

Fabrication and characterization of high energy density lithium-rich nickel manganese cobalt oxide cathode thin films

This paper reports a method to prepare Li-rich NMC (Li1.2Mn0.55Ni0.15Co0.1O2) thin film cathodes for Li-ion batteries using magnetron sputtering and post-annealing in O2. The use of thin films with no binder and conductive additives enables to study in detail the surface reaction chemistry upon cycling as well as the microstructural changes in the bulk. We show that it is essential to control the deposition pressure to obtain the expected layered(R-3m)-layered(C2/m) structure, thus providing large reversible capacities up to 270 mAh g-1 and voltage profiles close to those expected. This is substantiated by TEM/SAED results showing that the films consist of a layered structure with trigonal symmetry in which Li/TM ordering is achieved. The study of various XPS core levels determines that the surface is comprised of Mn4+, Co3+ and Ni2+ cations inside an O2- framework. The losses mechanisms are studied during long cycling. After 184 cycles, the microstructure does not reveal the presence of Li/TM ordering, which supports that Li2MnO3 conversion is irreversible. In addition, we characterize that the surface chemistry evolves significantly upon cycling. The surface of cycled discharged electrodes is mostly made of inorganic species (LiF, Lix POy Fz , LixPFy), along with small amounts of organic species with C-O and O-C=O groups such as PEO, LiOR and LiCO2R. Moreover, the results support that Ni and Co migrate into the bulk whereas Mn is enriched at the surface. In the case of Mn, the reduction of Mn4+ into Mn3+ is clearly evidenced, as expected from the activation of Li2MnO3 domains.

Baggetto, Loic↗