Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Cycle Performance”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Synthesis of Ti-based electrodes using Ti-salt flocculated sludge and their application in lithium-ion batteries

We report a simple strategy to synthesize the nanostructured TiO{sub 2} samples by a solid state reaction using Ti-salt flocculated sludge. The structure and morphology of the Ti-salt flocculated sludge, nanostructured TiO{sub 2} samples and pure commercial Aldrich TiO{sub 2} powder were characterized by powder X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The electrochemical performances were evaluated in coin type cells. Nanostructured TiO{sub 2} samples, obtained by Ti-salt flocculated sludge shows a higher capacity and better cycling performances than pure commercial Aldrich TiO{sub 2} powder at the cutoff of 1.0–2.5 V especially at high current rate. The enhanced cycling performance can be attributed to the facts that their high crystallinity and uniform nano-sized distribution.

36 MATERIALS SCIENCE↗
DOE OSTI2016

High grain boundary density Li{sub 4}Ti{sub 5}O{sub 12}/anatase-TiO{sub 2} nanocomposites as anode material for Li-ion batteries

Highlights: • Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites with high grain boundary density were synthesized. • {sup 7}Li NMR and impedance spectroscopy shows high Li-ion mobility in nanocomposites. • The shape of charge/discharge curves changes for nanocomposites. • Influence of particle size on cycling performance of lithium titanates was shown. • Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposite exhibits good cycling performance and rate capability. - Abstract: Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites are synthesized by a sol-gel method. The size of Li{sub 4}Ti{sub 5}O{sub 12} and TiO{sub 2} particles is of 4–5 and 7–10 nm, respectively. The obtained materials are characterized by XRD, SEM, HRTEM and BET. Ion mobility of the composites and their performance as anode materials for lithium-ion batteries are studied. According to the conductivity and {sup 7}Li NMR data, Li{sup +} mobility is much higher in the Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites as compared with that in pure Li{sub 4}Ti{sub 5}O{sub 12}. For Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites, marked changes in the charge–discharge curves are observed; charge–discharge rate and effective capacity at a high cycling rate are shown to increase. During the first cycle, charge capacity of these materials surpasses the theoretical capacity of Li{sub 4}Ti{sub 5}O{sub 12}. However, this parameter decreases sharply with cycling, whereas the discharge capacity remains almost unchanged. This phenomenon is attributed to the solid electrolyte interphase formation due to a partial electrolyte reduction on the Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} composite surface.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Highly crystalline sodium manganese ferrocyanide microcubes for advanced sodium ion battery cathodes

The microstructure and morphology of the crystal play an important role in the physical and electrochemical properties of electrode materials. Here we report a highly crystalline microcube structure of Na-rich Prussian white Na 1.92 Mn[Fe(CN) 6 ] 0.98 for sodium ion battery cathodes. The obtained structure features high crystallinity of the monoclinic structure with an average cubic size of 3–5 μm. Because of the improvement on microstructural and electrical properties, the cathode design enables promising electrochemical performance. The electrode exhibits an outstanding rate performance with reversible capacities of 152.8 mA h g –1 (10 mA g –1 ), 128.1 mA h g –1 (100 mA g –1 ), 118.7 mA h g –1 (500 mA g –1 ) and 110.3 mA h g –1 (1000 mA g –1 ). It also exhibits a good cycling performance with a capacity retention of 82% after 500 cycles at 100 mA g –1 . More importantly, the XRD analysis reveals a highly reversible monoclinic–cubic–monoclinic structural evolution of the cathode upon Na + extraction/insertion. The good rate and cycling performance can be attributed to the robust crystal structure with few defects and fast Na + transfer kinetics. The high purity single crystal morphology can also reduce the side reactions on the electrode/electrolyte interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Efficient sulfur host based on NiCo{sub 2}O{sub 4} hollow microtubes for advanced Li-S batteries

High energy density and cost effectiveness make lithium-sulfur battery a promising candidate for next-generation electrochemical energy storage technology. Here, we have synthesized a highly efficient sulfur host namely NiCo{sub 2}O{sub 4} hollow microtubes/sulfur composite (NiCo{sub 2}O{sub 4}/S). The hollow interior cavity providing structural integrity while sufficient self-functionalized surfaces of NiCo{sub 2}O{sub 4} chemically bind polysulfides to prevent their dissolution in the organic electrolyte. When used in lithium-sulfur batteries, the synthesized NiCo{sub 2}O{sub 4}/S cathode delivers high specific capacity (1274 mAh g{sup −1} at 0.2 C), long cycling performance at 0.5 C, and good rate capability at high current rates. - Highlights: • Hollow NiCo{sub 2}O{sub 4}/S microtubes were evaluated as an efficient sulfur host. • The designed 1D hollow architecture resulted in better cycling performance. • NiCo{sub 2}O{sub 4}/S delivered high capacity, long cycle life and good rate capability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Aqueous Polysulfide–Air Battery with a Mediator-Ion Solid Electrolyte and a Copper Sulfide Catalyst for Polysulfide Redox

Aqueous sodium polysulfide–air batteries are a promising system for enabling low-cost, high energy density, environmentally benign batteries for grid-scale deployment. However, the sluggish redox kinetics of aqueous polysulfide requires the use of a catalyst. Cobalt sulfide is a traditional catalyst with good activity and stability, but it uses expensive and toxic cobalt. This study demonstrates for the first time the long-term cycling performance of a sodium polysulfide–air battery with a low-cost copper sulfide catalyst for polysulfide redox. Alkaline sodium polysulfide anolyte is paired with an acidic sodium phosphate buffered air catholyte by means of a Na+-ion solid-state electrolyte, which eliminates chemical crossover between the two electrodes while serving as a mediator-ion solid electrolyte. Long-term cycling is achieved by means of a decoupled charge and discharge air electrode. Furthermore, the effect of CuS redox activity in the polysulfide–air voltage window is tested by pre-discharging CuS in LiOH and in NaOH. It was found that the sodium polysulfide–air batteries with CuS catalyst exhibit good cycling performance, with the overpotential only showing a modest increase of 0.09 V after 100 cycles. Batteries assembled with CuS pre-discharged in LiOH exhibit a small boost in performance, while batteries assembled with CuS pre-discharged in NaOH show a small performance decline.

25 ENERGY STORAGE↗
NASA NTRS1991

Accelerated cycle life performance for ovonic nickel-metal hydride cells

Nickel-Metal Hydride (Ni-MH) rechargeable batteries have emerged as the leading candidate for commercial replacement of nickel-cadmium (Ni-Cd) batteries. An important incentive is that the Ni-MH cell provides approximately twice the capacity of a Ni-Cd cell for a given size. A six-cell battery was committed to an accelerated cycle life test to determine the effect of separation type on performance. Results of the test may also show the Ni-MH battery to be a replacement candidate for the aerospace Ni-Cd battery.

Otzinger, Burton M.↗
DOE OSTI2016

Correlating Titania Nanostructured Morphologies with Performance as Anode Materials for Lithium-Ion Batteries

Titanium oxide is a ubiquitous and commonly used material in the environment. Herein, we have systematically probed the use of various hydrothermally derived titania (TiO2) architectures including zero-dimensional (0D) nano-particles, one-dimensional (1D) nanowires, and three-dimensional (3D) urchin-like motifs as anode materials for lithium- ion batteries. The structure and morphology of these nanomaterials were characterized using electron microscopy. The surface areas of these materials were quantitatively analyzed through Brunauer-Emmett-Teller (BET) adsorption measurements and were found to be relatively similar for both 1D and 3D samples with a slightly higher surface area associated with the 0D nanoparticles. Hence, to normalize for the surface area effect, readily available 0D commercial nanoparticles (Degussa P25), which possessed a similar surface area to that of as-prepared 1D and 3D materials, were also analyzed. Electrochemical analysis revealed a superior performance of hydrothermally derived 3D urchin-like motifs as compared with both as-prepared 0D and 1D samples as well as commercial Degussa P25. Our studies suggest the greater overall importance of morphology as opposed to surface area in dictating the eficiency of the Li ion diffusion process. Specifically, the 3D urchins yielded consistent rate capabilities, delivering 214, 167, 120, 99, and 52 mAh/g under corresponding discharge rates of 0.1, 1, 10, 20, and 50 C, respectively. Moreover, these 3D motifs gave rise to a stable cycling performance, exhibiting a capacity retention of ~90% in cycles 1-100 under a discharge rate of 1 C. Furthermore, the rate capability and cycling performance of our 3D hierarchical motifs were (i) comparable to those of anatase TiO /TiO -(B) hybrid structures even with little if any electrochemically promising bronze (B) phase herein and (ii) clearly nced as compared with previous results using similar anatase 3D microspheres.

25 ENERGY STORAGE↗
NASA NTRS2000

SAVANT: Solar Array Verification and Analysis Tool Demonstrated

The photovoltaics (PV) industry is now being held to strict specifications, such as end-oflife power requirements, that force them to overengineer their products to avoid contractual penalties. Such overengineering has been the only reliable way to meet such specifications. Unfortunately, it also results in a more costly process than is probably necessary. In our conversations with the PV industry, the issue of cost has been raised again and again. Consequently, the Photovoltaics and Space Environment Effects branch at the NASA Glenn Research Center at Lewis Field has been developing a software tool to address this problem. SAVANT, Glenn's tool for solar array verification and analysis is in the technology demonstration phase. Ongoing work has proven that more efficient and less costly PV designs should be possible by using SAVANT to predict the on-orbit life-cycle performance. The ultimate goal of the SAVANT project is to provide a user-friendly computer tool to predict PV on-orbit life-cycle performance. This should greatly simplify the tasks of scaling and designing the PV power component of any given flight or mission. By being able to predict how a particular PV article will perform, designers will be able to balance mission power requirements (both beginning-of-life and end-of-life) with survivability concerns such as power degradation due to radiation and/or contamination. Recent comparisons with actual flight data from the Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) mission validate this approach.

Chock, Ricaurte↗
DOE OSTI2018

Substituted thiadiazoles as energy-rich anolytes for nonaqueous redox flow cells

Understanding structure–property relationships is essential for designing energy-rich redox active organic molecules (ROMs) for all-organic redox flow batteries. In this paper we examine thiadiazole ROMs for storage of negative charge in the flow cells. These versatile molecules have excellent solubility and low redox potentials, allowing high energy density to be achieved. By systematically incorporating groups with varying electron accepting/withdrawing ability, we have examined substituent effects on their properties of interest, including redox potentials, calendar lives of charged ROMs in electrolyte, and the flow cell cycling performance. Finally, while the calendar life of energized fluids can be tuned in a predictable fashion over a wide range, the improvements in the calendar life do not automatically translate into the enhanced cycling performance, indicating that in addition to the slow reactions of charged species in the solvent bulk, there are other parasitic reactions that occur only during the electrochemical cycling of the cell and can dramatically affect the cycling lifetime.

25 ENERGY STORAGE↗
DOE OSTI2014

Advanced Surface and Microstructural Characterization of Natural Graphite Anodes for Lithium Ion Batteries

Natural graphite powders were subjected to a series of thermal treatments in order to improve the anode irreversible capacity loss (ICL) and capacity retention during long-term cycling of lithium ion batteries. A baseline thermal treatment in inert Ar or N2 atmosphere was compared to cases with a proprietary additive to the furnace gas environment. This additive substantially altered the surface chemistry of the natural graphite powders and resulted in significantly improved long-term cycling performance of the lithium ion batteries over the commercial natural graphite baseline. Different heat-treatment temperatures were investigated ranging from 950-2900 C with the intent of achieving the desired long-term cycling performance with as low of a maximum temperature and thermal budget as possible. A detailed summary of the characterization data is also presented, which includes X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and temperature-programed desorption mass spectroscopy (TPD-MS). This characterization data was correlated to the observed capacity fade improvements over the course of long-term cycling at high charge-discharge rates in full lithium-ion coin cells. It is believed that the long-term performance improvements are a result of forming a more stable solid electrolyte interface (SEI) layer on the anode graphite surfaces, which is directly related to the surface chemistry modifications imparted by the proprietary gas environment during thermal treatment.

Gallego, Nidia C↗
DOE OSTI2017

Encapsulation of Metallic Na in an Electrically Conductive Host with Porous Channels as a Highly Stable Na Metal Anode

Room-temperature Na ion batteries (NIBs) have attracted great attention because of the widely available, abundant sodium resources and potentially low cost. Currently, the challenge of the NIB development is due primarily to the lack of a high-performance anode, while the Na metal anode holds great promise considering its highest specific capacity of 1165 mA h/g and lowest anodic potential. However, an uneven deposit, relatively infinite volume change, and dendritic growth upon plating/stripping cycles cause a low Coulombic efficiency, poor cycling performance, and severe safety concerns. In this study, a stable Na carbonized wood (Na–wood) composite anode was fabricated via a rapid melt infusion (about 5 s) into channels of carbonized wood by capillary action. The channels function as a high-surface-area, conductive, mechanically stable skeleton, which lowers the effective current density, ensures a uniform Na nucleation, and restricts the volume change over cycles. As a result, the Na–wood composite anode exhibited flat plating/stripping profiles with smaller overpotentials and stable cycling performance over 500 h at 1.0 mA/cm 2 in a common carbonate electrolyte system. Finally, in sharp comparison, the planar Na metal electrode showed a much shorter cycle life of 100 h under the same test conditions.

09 BIOMASS FUELS↗
DOE OSTI2017

Preconceptual design of a fluoride high temperature salt-cooled engineering demonstration reactor: Core design and safety analysis

Engineering demonstration reactors are nuclear reactors built to establish proof of concept for technology options that have never been built. Examples of engineering demonstration reactors include Peach Bottom 1 for high temperature gas-cooled reactors (HTGRs) and Experimental Breeder Reactor II (EBR-II) for sodium-cooled fast reactors. Engineering demonstrations have historically played a vital role in advancing the technology readiness level of reactor technologies. This paper details a preconceptual design for a fluoride salt-cooled engineering demonstration reactor. The fluoride salt-cooled high-temperature reactor (FHR) demonstration reactor (DR) is a concept for a salt-cooled reactor with 100 megawatts of thermal output (MWt). It would use tristructural-isotropic (TRISO) particle fuel within prismatic graphite blocks. FLiBe (2 7LiF-BeF2) is the reference primary coolant. The FHR DR is designed to be small, simple, and affordable. Core design characteristics, fuel cycle performance, and safety analysis of the FHR DR preconcept have been evaluated. The FHR DR core design features a negative or negligible void coefficient throughout a reactor operating cycle. Both single-batch (cartridge) and multiple-batch fuel cycles can be demonstrated in the FHR DR. The single-batch cycle length of the FHR DR core is estimated at between 12-18 months, assuming the successful qualification of composite carbon (C/C) or silicon carbide (SiC/SiC) structural fuel block tie rod material. Fuel cycle performance of the FHR DR is similar to a high temperature gas-cooled reactor. Preliminary safety analysis of the FHR DR indicates that the reactor could be used to demonstrate the inherent safety characteristics of FHR designs.

Brown, Nicholas R.↗
DOE OSTI2025

Investigating the effect of screen-printed structured graphite electrodes with low tortuosity for high-capacity and fast-charging lithium-ion batteries

A flexible screen-printed graphite electrode was fabricated as an anode for developing fast-charging lithium-ion batteries with low tortuosity. A homogenous anode ink was prepared by mixing graphite as the active material, carbon black (C45) as the conductive additive, and polyvinylidene fluoride (PVDF) as the binder in N-Methyl-2-pyrrolidone (NMP) solvent. The ink was deposited on a flexible copper foil via a stainless-steel screen consisting of an array of pores, that act as secondary pore networks (SPNs), using the screen-printing process. Lithium-ion battery half-cells were assembled using the printed graphite anode, lithium metal foil as the counter electrode, and 1.2 M lithium hexafluorophosphate (LiPF 6 ) in ethyl carbonate: ethyl methyl carbonate (EC: EMC = 3:7) as the electrolyte. The effect of SPNs on the cell performance was investigated by performing formation, rate and cycling tests on the assembled cells, at different C-rates. It was observed that the cells consisting of SPNs with a pore size of 100 μm and edge-to-edge distance of 100 μm between the pores exhibited significantly higher specific capacities of 168 and 129 mAh/g when compared to reference cells without SPNs, which had capacities of 120 and 85 mAh/g, at high C-rates of 4 C and 6 C, respectively. The cells with SPNs also demonstrated excellent cycling performance with ~ 95% capacity retention after 100 cycles at 2 C.

Fast charging lithium-ion battery↗
DOE OSTI2023

Achieving stable all-solid-state lithium-metal batteries by tuning the cathode-electrolyte interface and ionic/electronic transport within the cathode

All-solid-state batteries with sulfide electrolytes and high-nickel layered oxide cathodes attract much interest due to their high specific energy. However, their cycling performance is primarily influenced by the interface between the sulfide electrolyte and the high-Ni layered oxide particles, which requires the use of composite cathodes with high ionic and electronic conductivities to achieve a kinetically stable interface inside the cathode. Here, we apply Ti 2 O 3 particles to the high-Ni cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), where Ti 2 O 3 not only acts as an electronic conductor to provide a fast diffusion path for electrons in the composite cathode, but also absorbs the lattice oxygen released from NCM811 cathode during cycling, stabilizing the Li 6 PS 5 Cl/NCM811 interface and suppressing electrolyte oxidation. The as-modified cathode exhibits an initial specific capacity of 192 mAh g -1 and retains 166 mAh g -1 after 140 cycles at 0.1C rate with a good capacity retention of 86.5%. Furthermore, the composite cathode displays high rate capability even at 1C rate. By contrast, the unmodified Li 6 PS 5 Cl/NCM811 cathode shows poor cycling performance with only 130 mAh g -1 remaining after 130 cycles. This work provides a new direction for the design of cathodes for all-solid-state batteries that can deliver high specific energy with long cycle life.

25 ENERGY STORAGE↗
DOE OSTI2024

Structure–performance relationships of lithium-ion battery cathodes revealed by contrast-variation small-angle neutron scattering

Lithium-ion battery cathodes are porous composites of active material, conductive carbon, and polymer binder. Controlling the cathode microstructure is key to achieving high energy density and cycling stability. Current characterization techniques lack the nanoscale resolution over representative volumes necessary to relate cathode microstructure to cycling performance. To address this challenge, we utilize contrast-variation small-angle neutron scattering to quantify the chemical and structural features of cathodes wet by dimethyl carbonate, representing a relevant solvent environment. Using neutron scattering measurements, we identify an expansion in carbon and polymer structures that arises after calendering and wetting with solvent. Further, we deconvolute the carbon and binder phases to obtain the solvent-accessible carbon black surface area, which we correlate to diminished capacity retention driven by electrolyte decomposition on exposed carbon. This technique provides nanoscale insight into composite cathode microstructures and resulting cycling performance, promising future applications to a broad range of porous materials that exist in energy storage systems.

25 ENERGY STORAGE↗
DOE OSTI2014

Bis(fluoromalonato)borate (BFMB) anion based ionic liquid as an additive for lithium-ion battery electrolytes

Propylene carbonate (PC) is a good solvent for lithium ion battery applications due to its low melting point and high dielectric constant. But, PC is easily intercalated into graphite causing it to exfoliate, killing its electrochemical performance. We report on the synthesis of a new ionic liquid electrolyte based on partially fluorinated borate anion, 1-butyl-1,2-dimethylimidazolium bis(fluoromalonato)borate (BDMIm.BFMB), which can be used as an additive in 1 M LiPF6/PC electrolyte to suppress graphite exfoliation and improve cycling performance. Additionally, both PC and BDMIm.BFMB can be used synergistically as additive to 1.0M LiPF6/methyl isopropyl sulfone (MIPS) to dramatically improve its cycling performance. It is also found that the chemistry nature of the ionic liquids has dramatic effect on their role as additive in PC based electrolyte.

25 ENERGY STORAGE↗
DOE OSTI2023

Elucidating Primary Degradation Mechanisms in High-Cycling-Capacity, Compositionally Tunable High-Entropy Hydrides

The hydrogen sorption properties of single-phase bcc (TiVNb) 100–x Cr x alloys (x = 0–35) are reported. All alloys absorb hydrogen quickly at 25 °C, forming fcc hydrides with storage capacity depending on the Cr content. Here, a thermodynamic destabilization of the fcc hydride is observed with increasing Cr concentration, which agrees well with previous compositional machine learning models for metal hydride thermodynamics. The steric effect or repulsive interactions between Cr–H might be responsible for this behavior. The cycling performances of the TiVNbCr alloy show an initial decrease in capacity, which cannot be explained by a structural change. Pair distribution function analysis of the total X-ray scattering on the first and last cycled hydrides demonstrated an average random fcc structure without lattice distortion at short-range order. If the as-cast alloy contains a very low density of defects, the first hydrogen absorption introduces dislocations and vacancies that cumulate into small vacancy clusters, as revealed by positron annihilation spectroscopy. Finally, the main reason for the capacity drop seems to be due to dislocations formed during cycling, while the presence of vacancy clusters might be related to the lattice relaxation. Having identified the major contribution to the capacity loss, compositional modifications to the TiVNbCr system can now be explored that minimize defect formation and maximize material cycling performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Energy Impacts of Oversized Residential Air Conditioners -- Simulation Study of Retrofit Sequence Impacts

This research addresses the question of what are the energy consequences for oversizing of an air conditioner in a home. Conventional wisdom holds that oversizing the AC results in significant energy penalties. However, the reason for this was shown to be due to crankcase heaters and not due to cycling performance of the AC, and is only valid for a particular set of assumptions. Adding or removing individual characteristics, such as ducts or crankcase heaters, can have measurable impacts on energy use. However, with all other home characteristics held constant, oversizing the AC generally has a small effect on cooling energy use, even if the cycling performance of the unit is poor. The relevant aspects of air conditioner modeling are discussed to illustrate the effects of the cycling loss coefficient, Cd, capacity, climate, ducts and parasitic losses such as crankcase heaters. A case study of a typical 1960's vintage home demonstrates results in the context of whole building simulations using EnergyPlus.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗