bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Polyvinylidene Fluoride (PVDF) Binder Properties on LiNi0.33Co0.33Mn0.33O2 (NMC) Electrodes Made By a Dry-Powder-Coating Process
Authors: Wang Ming , Hu Jiazhi , Wang Yikai , Cheng Yang-Tse 
Published: February 2020

A typical electrode fabrication process starts with mixing active materials, conductive agents, polymeric binders, and solvents to form a slurry. Polyvinylidene fluoride (PVDF) is a commonly used binder, which requires N-Methyl-2-pyrrolidone (NMP) as the solvent. The usage of NMP increases the material and manufacturing cost of the electrode because NMP is expensive, toxic, and flammable, as well as requiring energy to dry and capture. Electrostatic spray deposition (ESD), a dry-powder-coating process, is one of the promising methods to eliminate the usage of organic solvents. The influence of PVDF properties on wet-slurry-coated electrodes has been investigated extensively, their effects on the electrodes made by the dry-powder-coating process are still unknown.
In this presentation, we report the effects of the molecular weight of the PVDF binder on the electrochemical performance and mechanical integrity of the NMC electrodes made by a dry-powder-coating process. The microstructure, binding strength, and electrochemical behavior of the electrodes made with two types of PVDF polymers were compared. The results show that a thin layer of PVDF formed on NMC surface after the thermal activation process, acting as both binding points and lithium intercalation/deintercalation barriers in the dry-powder-coated electrode. The microstructure and porosity of the PVDF layer depend strongly on the molecular weight of the PVDF. By increasing the molecular weight of the PVDF, the layer becomes more porous, and capacity retention can be improved without decreasing the binding strength and long-term cycling performance.
(Invited) Investigation of Megahertz Frequency Modulation Effects on Charge and Discharge Behavior of Lithium Ion Batteries
Authors: Wen Bohua , Tsai Ping-chun , Chiang Yet-Ming 
Published: February 2020

Over the past several years, reports have emerged of ultrafast charging algorithms for lithium ion batteries [1,2] that in at least one instance [3] is attributed to megahertz frequency modulation of charging/discharging currents. Such algorithms are claimed to dramatically improve active material utilization as well as cycle life, but no mechanisms have been proposed in published work, nor, to our knowledge, have mechanistic studies have been conducted. In this work, we use a recently developed technique [4] in which single electrode particles having capacities of a few nAh can be interrogated with electrodynamic measurements (EIS, GITT, polarization-depolarization) while varying the state-of-charge. This capability allows clean separation of interfacial vs bulk transport limitations at the individual particle level, without complicating factors from typical composite electrode microstructures. To this capability, we have added AC pulse charging and discharging at ultra-low currents (down to picoA) with high-frequency waveforms (up to ~ MHz).
With this capability, we aim to answer a number of questions such as: Are these effects real? Are they significant? And, what are possible mechanisms by which ion transport kinetics in a lithium ion battery are responsive to megahertz frequency excitation?

This work was supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012583.

References:

https://techcrunch.com/2015/05/05/nucleus-scientific-launches-to-revolutionize-batteries/

https://www.greencarreports.com/news/1121116_company-claims-to-harness-ai-for-quicker-electric-car-dc-fast-charging

Sherstyuk et al., Extended life battery, US Patent No. 9,966,780B2, May 2018.

P.-C. Tsai, B. Wen, M. Wolfman, M.-J. Choe, M. S. Pan, L. Su, K. Thornton, J. Cabana, Y.-M. Chiang, Single-particle measurements of electrochemical kinetics in NMC and NCA cathodes for Li-ion batteries. Energy Environ. Sci., 2018, 11, 860-871.
Electrochemical Modeling and Experimental Investigation of Aging Mechanisms on NCA and Graphite Electrodes Harvested from Off-Grid PV Lithium-Ion Cells
Authors: Benavente Fabian Andres , Ko Jing Ying , Lundblad Anders Olof , Ekström Henrik , Lindbergh Göran 
Published: February 2020

Modelling of electrochemical impedance spectroscopy (EIS) to predict aging in lithium ion batteries is a useful tool when performing a diagnosis of the state of health (SOH) of the battery. Aging of lithium ion batteries happens in applications from electric vehicles to stationary systems and is associated to capacity fade and impedance increase [1]. By predicting the aging parameters through modeling of EIS from separated electrodes, it is possible to estimate the SOH of the full cell and therefore improve its performance. In this work NCA and graphite electrodes were harvested from cylindrical cells aged under an off-grid PV/Battery system conditions and analyzed by means of EIS to determine the causes of electrode deterioration.
The NCA/graphite cylindrical cells were calendar aged and cycle-aged between SOC 20-50 %, 35-65 %, 60-90 % and 20-95 % until end of test (EOT) is reached (e.g. 1000 cycles). The impedance behavior of the calendar and cycle aged cells were measured. Each electrode is carefully harvested once reached the EOT and electrochemically characterized using symmetric cells by means of EIS.
A physics-based impedance model is employed to fit the experimental EIS of symmetrical cells using a least square fitting tool in COMSOL® Multiphysics 5.4. It is based on the pseudo two-dimensional (P2D) model [2] incorporating intercalation kinetics, mass and charge transport based on concentrated solution porous electrode theory. The model additionally accounts for double layer effect and aging mechanisms. Using the model, useful aging parameters were parameterized, and the variation of the aging parameters with different aging history was validated with the support of scattered electron microscopy (SEM) technique. Among the aging mechanisms described, an increase in the local contact resistance between the active material and the conductive carbon, and decrease in particle size due to particle cracking and further film formation due to SEI are considered. The impedance model parameters from both electrodes are then linked to the aging process observed on experimental full cell.
Figure 1 shows the fitting and experimental curves for graphite Nyquist plot, in which we observe a good fitting specifically at low frequencies. Although the model predicts a second semicircle in the middle requency range, the experimental curve also shows a time constant element which can be considered as a truncated semicircle in the same region.
[1] T. G. Zavalis, M. Klett, M. H. Kjell, M. Behm, R. W. Lindström, G. Lindbergh, Electrochemica Acta, 110 (2013) 335-348.
[2] J. Newman and W. Tiedemann, AIChE J., 21, 25–41 (1975).

Figure 1
Life Prediction of Lithium Ion Battery for Grid Scale Energy Storage System
Authors: Hashimoto Tsutomu , Kanamura Kiyoshi 
Published: February 2020

As renewable energy with large output fluctuation increases, adoption of a large power storage system in which lithium ion secondary batteries are series-parallelized has been started for stabilization of grid power. However, stationary storage systems may be charged and discharged under more severe conditions than batteries for electric vehicles, and may deteriorate in a short period of time. In this research, while analyzing the change of capacity and internal resistance of the lithium ion secondary battery which uses LFP for the cathode and carbon anode. We estimated the life when charging and discharging under the conditions of ancillary service*, and considered the proposed measures for prolonging the life.
* ancillary service; A power adjustment method for stabilizing grid transmission

Experiment

A sample cell using an electrode (57 mm × 40 mm) including LiFePO4 for the positive electrode and carbon for the negative electrode was used. As evaluation methods, temperature and charge / discharge cycle tests with different charge / discharge rates and calendar life tests were conducted to analyze cycle characteristics and time characteristics of capacity and internal resistance.

Results and Discussion

2.1 Cell performance

The LFP cell produced in this study had an average voltage of 3.05 V (during 1 C discharge), an initial capacity of 1.0 Ah (during 1 C discharge), and a DC resistance of 16 mΩ (SOC 50%). When 1 C charge and discharge were repeated in the initial cell, the temperature rose to 31.1 °C. under natural cooling conditions of 24.9 ° C. outside temperature.

2.2 Degradation characteristics

The capacity decrease is highly dependent on SOC, and in the state of 90% of SOC, the capacity decrease was about twice as fast as 50% of SOC. On the other hand, the increase in resistance was highly temperature-dependent, and the capacity decrease was about twice as fast as at 25 ° C. at 45 ° C. conditions. Also, multiple degradation mechanisms exist because at least two or more inflection points exist, not following the 1/2 power of time, which is the degradation tendency of a general lithium ion secondary battery.

2.3 Life prediction of LIB for grid scale energy storage system

There are many ways to operate the stationary storage system, but as a power adjustment method to stabilize power transmission of the system, the result of predicting the degradation behavior when the battery is operated under the test condition of ancillary service reported by PJM. It has been found that if the number of cells in parallel is reduced to increase the output power per unit cell, the deterioration is accelerated due to the influence of the temperature rise of the cells.

Figure 1
(Amazon Catalyst at ECS Grant Winner) Enhancing the Rate of Electrocatalytic Conversion of N2 to NH3 Using Bimetallic Au-Pd Nanoparticles
Authors: Nazemi Mohammadreza , El-Sayed Mostafa 
Published: February 2020

Ammonia is one of the widely produced chemicals in the world, with broad applications in producing nitrogen-based fertilizer, energy, and in the pharmaceutical industry. The current industrial method for ammonia production is energy intensive and heavily relies on fossil fuels, which are responsible for environmental pollution. To meet ammonia demands, it is necessary to develop sustainable and environmentally friendly production methods that consume significantly less energy than the current methods. Here, the use of hollow gold nanocages (AuHNCs) as an effective electrocatalyst is evaluated for electrochemical nitrogen reduction reaction (NRR) under ambient conditions. The electrochemical experiments are carried out at various potentials in 0.5M LiClO4 aqueous solution using AuHNCs, and their catalytic efficiency is determined for the conversion of nitrogen to ammonia [1, 2]. The highest ammonia Faradaic efficiency (30.2%) is achieved at−0.4 V vs. RHE while the highest ammonia yield (3.9 μg cm-2 h-1) is obtained at −0.5 V vs. RHE. The electrocatalytic activity of NRR using AuHNCs is further compared with that of solid Au nanoparticles of various shapes (i.e., rods, spheres or cubes) to elucidate the enhanced rate of the reaction resulting from the increase in surface area and confinement effects. The three-fold enhancement in ammonia Faradaic efficiency is achieved by using the AuHNCs (30.2%) compared to the solid Au nanocubes (11.4%) [1]. It has been demonstrated that electrochemical N2 reduction for NH3 production using Pd nanoparticles requires lower overpotential and results in higher electrocatalytic efficiency for NH3 compared with Au nanoparticles. The use of Pd and hybrid Au-Pd nanoparticles is evaluated for electrochemical nitrogen reduction reaction (NRR) under ambient conditions. The results are further complemented by in-situ surface-enhanced Raman spectroscopy (SERS) and ex-situ
1H NMR to monitor the trace amount of NH3 over the course of the experiment and elucidate the possible differences in the reaction mechanism for electrosynthesis of NH3 on Pd and Au surfaces.

References

[1] Nazemi, M., Panikkanvalappil, S.R. and El-Sayed, M.A., 2018. Enhancing the rate of electrochemical nitrogen reduction reaction for ammonia synthesis under ambient conditions using hollow gold nanocages. Nano Energy, 49, pp.316-323.
[2] Nazemi, M. and El-Sayed, M.A., 2018. Electrochemical Synthesis of Ammonia from N2 and H2O under Ambient Conditions Using Pore-Size-Controlled Hollow Gold Nanocatalysts with Tunable Plasmonic Properties. The journal of physical chemistry letters, 9(17), pp.5160-5166.
Exchange-Coupled Sm2Co17/FeCo Core-Shell Nanomagnets Via the Combination of Electrospinning and Electroless Deposition
Authors: Lee Jimin , Yoo Bongyoung , Kim Hee Taik , Kim Jongryoul , Choa Yong-Ho 
Published: February 2020

In this study, we performed a novel synthesis of one-dimensional (1-D) SmCo/FeCo core-shell nanomagnets with noticeably enhanced exchange-coupling interactions via electrospinning and a subsequent heat treatment process coupled with an electroless plating process. We discuss the influence of the 1-D shape in enhancing the magnetic properties, particularly exchange-coupling interactions of the rare-earth magnet, compared to the zero-dimensional (0-D) core-shell magnet.
With the advent of high-efficiency miniaturized devices in modern industry, there is high demand for enhanced permanent magnets. Their applications are wide-ranging and include motors in automobiles, data storage devices, electromechanical devices, and electronics. Theoretically, one way to improve the inherent magnetic properties of rare-earth nanomagnets (i.e., SmCo) is to fabricate a soft magnet (i.e., FeCo)-coated core-shell nanomagnet that participates in exchange-coupling interaction with the interphase. However, many previous reports showed only marginal enhancement in magnetic properties, ascribed to the inevitable tendency of 0-D nanoparticles to agglomerate, resulting in non-ideal magnetic coupling. Moreover, there have been no reports on SmCo-based core-shell nanoscale magnets with a 1-D structure, and the effect of magnet shape on the magnetic properties (particularly on exchange-coupling effect) is not well understood. In this regard, such a comparison is a meaningful approach in the design of permanent magnets for achieving effective magnetic coupling.
We clarified the distinct effect of magnet shape based on the analytical results. Interestingly, despite the tailored thickness of the FeCo layer on the Sm2Co17, there was no increase in magnetization or (BH)max enhancement in 0-D magnets, resulting from agglomeration, while 1-D magnets showed an all-time high effective exchange-coupling interaction. Substantial enhancement in magnetization and a (BH)max value of about 10.14 MG·Oe were obtained in the 1-D nanostructure, representing straightforward enhancement of greater than 145% compared to 0-D magnetic nanostructures.
Our work also elucidates the magnetic behavior within the hard-soft magnetic phases of the 1-D SmCo/FeCo nanocomposite, including a comparison with the 0-D bi-magnet. We expect that this understanding can be extended to synthesis of a super-strong exchange-coupled magnet, overcoming the limitations of traditional magnetic materials. Moreover, the present work would be of particular interest to researchers working on a broad range of syntheses and advanced magnetic devices.

Figure 1
Evaluating Li/CFx Cell Components for Deep Space Space Exploration
Authors: Brandon Erik J. , Billings Keith J. , Ratnakumar Bugga V. , Chin Keith B. , Jones John-Paul , Jones Simon C. , Pasalic Jasmina , Ruiz John Paul , Seong Jessica , Stariha Sarah A. 
Published: February 2020

To meet the future demands of space exploration will require primary batteries offering higher specific energy, relative to heritage space rated cells based on Li/SO2, Li/SOCl2 and Li/MnO2 chemistries. Cells based on the Li/CFx chemistry are currently under development to support operations in challenging extreme environments. One such proposed application of advanced primary cells is for a proposed Europa Lander, which would analyze the icy surface of this Jovian moon, evaluate its potential for habitability, and investigate for signs of bio-signatures. To address this unique mission requires a detailed understanding of the effects of wide temperatures and radiation on cell electrical and thermal performance, self-discharge characteristics and reliability. In particular, results from screening of cell components will be reviewed, including electrodes and electrolytes experiencing high doses of ionizing radiation.
The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the Europa Lander Pre-Project.
Advanced Li Metal Batteries: Thermal Safety Evaluation, Analysis and Mechanistic Elucidation
Authors: Puthusseri Dhanya , Pol Vilas G. 
Published: February 2020

High theoretical capacity coupled with low operating potential makes Lithium the most promising choice for next-generation batteries. Replacing graphite by Li metal can enhance the energy density three times as compared to conventional Li-ion battery. Lithium is also an essential part of the next generation high energy batteries such as Lithium-Sulphur and Lithium-air batteries. However, the high reactivity of Li metal with electrolyte leads to dendritic growth, poor cycle life and safety hazards in Li metal batteries. Till date, there has been no study on the thermal characteristics of Li metal batteries.
The thermal characteristics of Li metal batteries using advanced multiple-mode calorimetry (MMC) for the coin cell format under fully charged and discharged conditions is studied. In the conventional differential scanning calorimetry (DSC) ex-situ studies of a component or two from the battery, possibly could lead to some artifacts. Therefore, MMC is utilized to directly study the thermal behavior of whole coin cell comprising anode, cathode, electrolyte, and separator with thermally stable leak proof gasket till 300 oC. Thermal runaway of two types of Li metal batteries with different chemistries namely Li-Sulfur and Li-NMC are measured and compared. The MMC of Li-S battery coin cell in fully charged conditions showed a sharp exothermic peak positioned at 180 °C originating from the reaction between the Li metal and sulfur in presence of the electrolyte. Though Li-S batteries are assumed to be safer, an exothermic reaction between Li and S cathode leads to thermal runaway once the Li metal melts. The MMC of Li-NMC cell in the coin cell format also exhibits endothermic and exothermic peaks arising from the melting of Li and reaction of Li with electrolyte/cathode. This exothermic reaction leads to thermal runaway in Li-NMC around 180°C. The detailed endothermic and exothermic heat generation values in J/g, peak temperature, its source based on interfacial reactions and mechanistic elucidation will be discussed.
(Invited) An Evaluation of Electrochemical Properties for a Series of Sodium-Ion Battery Anodes
Authors: Johnson Christopher S. 
Published: February 2020

It is now established from battery pack engineering modeling calculations, that a Na-ion battery operating at 3.3 V, employing an anode (negative electrode) with a capacity of 500 mAhg-1, and a 200 mAhg-1 cathode (positive electrode) will provide upwards of 15-20% higher energy density (gravimetric basis) over current Li-ion batteries (i.e. 200-225 Whkg-1).1 Of course, reaching such capacity goals of the anodes and cathodes for Na-ion batteries remains very challenging. In this presentation, a number of anode materials’ chemistry and electrochemistry will be evaluated and discussed. These systems include sodium alloys with Sn, Sb, Bi, Ge in carbon-composite particles or in elemental thin-film form, SnSb intermetallics, nano-tube TiO2 and Na2-xHxTi2O4(OH)2, conversion anodes like Sb2O4, Co3O4, Fe2O3, Fe3O4, PbO, Pb3O4, Sn-Na2O conversion-alloying composite, and lastly, spherically-shaped hard carbons. Notably, the Sn-Na2O conversion-alloying composite yields promising target 500 mAhg-1 capacity at C/10 rate for 500 cycles. An interesting mechanism is at work here, whereby the Na-Sn forms an amorphous Zintl phase such that the negative charge at deep sodiation collects on the Sn atom in the compound. This process is believed to minimize overall volume changes in the (de)sodiation process which aids in the good reversibility of the material.
[1] http://www.cse.anl.gov/batpac/index.html
Synergistic Effect of 3D Current Collectors and ALD Surface Modification for High Coulombic Efficiency Lithium Metal Anodes
Authors: Chen Kuan-Hung , Sanchez Adrian J. , Kazyak Eric , Davis Andrew L. , Dasgupta Neil P. 
Published: February 2020

Improving the performance of Li metal anodes is a critical bottleneck to enable next‐generation battery systems beyond Li‐ion. However, stability issues originating from undesirable electrode/electrolyte interactions and Li dendrite formation have impaired long‐term cycling of Li metal anodes. In this work, we have developed a bottom‐up fabrication process of vertically aligned and highly uniform Cu pillar arrays on a Cu foil via templated electrodeposition for use as a 3D current collector.[1] By rationally controlling geometric parameters of the 3D current collector architecture, including pillar diameter, spacing, and length, we have demonstrated the morphology of Li plating/stripping upon cycling can be controlled and optimal cycling performance can be achieved.
In addition, we showed that deposition of an ultrathin layer of ZnO by atomic layer deposition on the current collector surface can facilitate the initial Li nucleation, which dictates the morphology and reversibility of subsequent cycling. This core–shell pillar architecture allows for the effects of geometry and surface chemistry to be decoupled and individually controlled to optimize the electrode performance in a synergistic manner. Using this model platform, we have demonstrated Li metal anodes with Coulombic efficiency up to 99.5% at 0.5 mA/cm2 and 99.4% at 1 mA/cm2, which are among the highest reported values to date. The results gained from this work can thus provide a pathway toward high‐efficiency and long‐cycle life Li metal batteries with reduced excess Li loading.
[1] K.-H. Chen, A.J. Sanchez, E. Kazyak, A.L. Davis, N.P. Dasgupta, Adv. Energy Mater.
9, 1802534 (2019).