bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Sodium-Ion Intercalation Reaction at Graphite Electrodes
Authors: Kondo Yasuyuki , Fukutsuka Tomokazu , Miyazaki Kohei , Abe Takeshi 
Published: February 2020

Introduction

Sodium-ion batteries (SIBs) are widely focused on as post lithium-ion batteries (LIBs) from the view of element strategy[1]. Hard carbon electrode is often used as the negative electrode of sodium-ion battery. This is because the graphite electrodes show negligible reversible capacity different from LIBs. Graphite is cheaper and has higher density than hard carbon, and therefore, graphite negative electrode for SIBs should be quite attractive. However, it is well-known that sodium-ion insertion at graphite electrode is very difficult although the reason has not been clarified yet. In this study, the sodium-ion intercalation reaction at graphite electrodes in organic electrolyte solutions was investigated to understand the sodium-intercalation mechanism.

Expetimental

Electrochemical measurements were carried out using a three-electrode cell. Working electrode was graphite composite electrode (natural graphite and graphitized carbon nanosphere[2] (GCNS)). Reference electrode was Ag/Ag+ electrode and counter electrode was natural graphite composite electrode. The electrolyte solution was 0.9 mol kg-
1 sodium bis(fluorosulfonyl)amide (NaFSA)/ethylene carbonate (EC) + dimethyl carbonate (DMC) (1:1 by vol.). Cyclic voltammetry and charge-discharge measurements were carried out. To characterize the sodium intercalated graphite, Raman spectroscopy and X-ray diffraction (XRD) measurement were used.

Results

Figure 1 shows cyclic voltammograms of natural graphite composite electrode in 0.9 mol kg-
1 NaFSA/EC+DMC(1:1 by vol.). Reversible sodium-ion intercalation was not indicated. In charge-discharge curves, large irreversible capacity was observed at the 1st cycle. Reversible capacity was around 5 mAh g-
1. Thus, a small amount of reversible sodium-ion intercalation into graphite was indicated. The XRD patterns for graphite electrodes held at -3.03 V vs. Fc/Fc+ during from 1day to 7 days didn’t change compared with the XRD pattern for pristine graphite electrode. Figure 2 shows Raman spectra of the graphite electrode held at -3.03 V vs. Fc/Fc+. After 1day, G-band around 1580 cm-
1 was split and a new band around 1600 cm-
1 derived from intercalated species[3] appeared. The ratio of band intensity indicated the formation of stage-5 sodium graphite intercalation compound (Na-GIC). The intensity of the new band increased with increasing potential holding time, and the formation of lower stage Na-GIC was indicated. Therefore, the formation of Na-GIC was limited on the surface region of graphite. It suggests that the diffusion of sodium-ion in graphite is very slow.
In the meeting, the results for GCNS will be reported.

Acknowledgement

This work was partially supported by ESICB, Kyoto University.

Reference

S. Komaba et al., Adv. Funct. Mater., 21 (2011) 3859.

N. Yoshizawa et al., Mater. Chem. Phys., 121 (2010) 419.

M. S. Dresselhaus and G. Dresselhaus., Adv. Phys.,
51 (2002) 1.

Figure 1
Rechargeability of Manganese Dioxide-Zinc Batteries
Authors: Bonakdarpour Arman , Mehta Sean , Afonso Greg , Wilkinson David P. 
Published: February 2020

Primary alkaline batteries use electrolytic manganese dioxide (EMD) as the cathode and zinc as the anode and have been in commercial use for several decades. This chemistry is of great interest because the materials used are inexpensive, environmental friendly, and abundant. In addition, alkaline chemistry offers a better energy density and shelf life than some other aqueous batteries such as lead-acid technology. Rechargeability of EMD, however, is challenging and commercial rechargeable batteries based on this electrochemistry have faced limited success due to the limitation of cycling performance. We have investigated the causes of cycling failures using flatplate-type cathode (MnO2) and anode (Zinc) electrodes which are amenable to large scale production. Electrochemical and physiochemical characterizations were performed and will be presented.
Flatplate-type electrodes were prepared by producing paste-like mixtures of cathode and anode materials and applying them onto expanded Ni (cathode) and expanded brass (anode) current collectors. The cathode mixture contained EMD, graphite, additives, SBR binder and CMC gelling agent. Anode mixtures were prepared from zinc, zinc oxide, hydrogen inhibitors, teflon binder and carbapol gelling agent. The alkaline electrolyte (9M) was prepared from DI-water and KOH salt. All the cell hardware used was developed in-house. For the cathode electrode, a number of chemical additives such as BaSO4, Sr(OH)2·8H2O, Ca(OH)2, and Bi2O3were investigated at 5 wt. %.
Deep discharge cycling (to 1.1 V) reduces the initial specific capacity of 250 mAh g-1 by 50% after 20 cycles. The specific capacity reduces, although at a slower rate, to about 50 mAh g-1 after 100 cycles. Additives such as BaSO4show marginal improvement in the earlier cycles (cycles 10-50), but beyond cycle 50 no noticeable effect was observed. Deeper cycling can be combined with shallow depths of discharge (1.4 – 1.45 V) to extend the cycle life-time of the batteries. Figure 1 shows the cycling performance of RAM cells for combined deep/shallow depths of discharge at C/2 and C/10 rates.
Post-cycling XRD analysis of the cathode electrode shows formation of a todorokite-like phase which could limit the cycling performance. Impedance studies show a rapid increase in the charge transfer resistance, indicating that formation of surface inactive phases also play a role in reducing the capacity upon cycling.

Figure 1
Elevated Temperature Lithium Rechargeable Batteries: Motivation and Challenges
Authors: Addison Dan , Giordani Vincent , Uddin Jasim , Tan Hongjin , Chase Gregory V 
Published: February 2020

During the last three decades, research and development in lithium-based rechargeable batteries has primarily focused on cells that are designed to operate at or near ambient temperature. The most successful technology in the field, namely Li-ion cells with intercalation electrodes and organic electrolyte, has enabled the wireless device industry, but it is not ideally suited for long-range, light-duty vehicles, particularly with respect to cost, capacity and abuse tolerance. Alternative electrodes, cell chemistries, and electrolyte materials under development continue to target operation at or near ambient temperature.
This presentation describes research and development at Liox Power, Inc. into high energy lithium rechargeable batteries that operate in the 80 °C to 200 °C temperature range. Specific motivations and challenges will be provided, particularly vis à vis new electrolyte materials, lithium metal electrodes and high energy positive electrode materials. Improvements in properties at elevated temperature expected from Arrhenius behavior will be noted, but we particularly focus on identification of physical phenomena (e.g. phase behavior) that may be uniquely accessed in this temperature range. Results demonstrating substantial improvements in key figures of merit that currently limit advanced rechargeable lithium battery chemistries will be provided.
Countering Degradation of Carbon Felt Electrodes in All-Vanadium Redox Flow Batteries (VRFB)
Authors: Derr Igor , Roth Christina 
Published: February 2020

Carbon felt electrodes are used as electrode material in VRFB. The main reasons to use carbon felt electrodes are their corrosion resistance in acidic electrolyte, high overpotential towards hydrogen evolution reaction and low material costs.
Different origins of degradation can be related to dynamic cycling conditions or to possible side reactions. Chemical degradation or aging on the other hand can be caused by simple contact with the electrolyte. The static aging and the dynamic degradation of heat-treated carbon felt electrodes in all-Vanadium redox flow battery systems were investigated by different electrochemical and analytical methods. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to determine the performance loss of the carbon-based electrodes. Different characterization methods, such as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), were applied to study cause and effects of material’s degradation.
Chemical aging was found to take place during the first 6 days of mere contact with the electrolyte (1.6 M V3+/4+, 2 M H2SO4, 0.05 M H3PO4). Both, the charge transfer resistance and the diffusion resistance increased with time. Electrochemical degradation was observed for 50 charge and discharge cycles of a 10 cm2 cell with flow-through design and 100 mL of electrolyte. The half-cell potentials shifted towards more negative potentials with an increasing amount of cycles. Chemical aging and electrochemical degradation have a strong impact on the negative half-cell. XPS and SEM reveal that the main reason for the observed performance loss is a decrease of electrochemically active surface area (ECSA) due to the oxidation of the carbon felt to CO and CO2.
The durability of the electrodes was increased by introducing bismuth coated electrodes in the negative half-cell. Bismuth was deposited on the carbon felt with a pulse deposition protocol out of an aqueous solution. Charge and discharge experiments exhibited a more stable performance compared to pure carbon felt electrodes. The half-cell potentials remained constant during cycling but the overall cell resistance was higher, because the electrical conductivity of bismuth is lower compared to graphitic carbon.
Non-Aqueous Redox Flow Batteries Based on Polyoxometalates
Authors: Chen Jee-Jay James , Barteau Mark Alan 
Published: February 2020

Renewable energy generation around the world continues to see dramatic growth. According to a recent U.S. Energy Information Administration (EIA) report, 13% of US energy demand in 2013 was met by renewables and the amount is still increasing. Large scale energy storage systems promise to increase the effectiveness of renewable energy sources. Redox Flow Batteries (RFB) represent a highly scalable approach. Traditional RFBs are mostly aqueous which limits their operating voltage range due to water splitting. Non-aqueous systems offer a larger voltage window. Polyoxometalates (POMs), which exhibit versatile redox properties and multiple electron transfers were used as the active species in non-aqueous RFBs. POMs generally contain group 5 or group 6 transition metals linked by oxygen atoms and centered around a heteratom. Common POMs are of the Keggin type ([XM12O40]q−, where X = P, Si, Ge, etc., and M = Mo, W, V, etc. ) or Wells-Dawson type ([X2M18O62]q-). The redox properties of POMs can be altered by exchanging the framework metal atoms or the central heteroatom very easily.
Li3PMo12O40, Li4PMo11VO40 and Li6P2W18O62 were tested in acetonitrile and the lithium was chosen as the counter-cation in order to avoid H2 generation. Owing to limitations on the transport rate of Li+ through conventional proton-exchange membranes such as Nafion, an aramid nano-fiber (ANF) membrane was utilized for charge-discharge experiments. The low permeability of ANF prevents the POM crossover, with less than 1% crossover observed after one week. Greater than 85% coulombic efficiency was observed for symmetric cells containing the POMs above, with good reversibility and stability. Both symmetric and asymmetric cells (different POMs utilized for the anolyte and catholyte) were tested. Asymmetric POM-based RFBs hold promise for increasing the voltage window and overall energy density.
Parametrization and Validation of a Vanadium-Redox-Flow Cell Model
Authors: Kleinsteinberg Björn , Çerçi Ayşen , Sauer Dirk Uwe 
Published: February 2020

Performance improvement of electrochemical energy storage systems is a continuous process. Every application has its unique requirement profiles. In the field of stationary energy storage the cyclability is an important feature, flow batteries are beneficial for applications with high numbers of cycles. This study focuses on Vanadium-Redox-Flow Batteries (VRFB) to improve an existing cell design. Production of prototypes is expensive, but with a good model optimized geometries can be predicted. A key task is the precise validation of the model to minimize the errors. In this study a model of a VRFB is developed in COMSOL Multiphysics and it is evaluated with measurements on the cell itself.
The model is based on a laboratory cell. It consists of graphite felts as electrodes, separated by an ion exchange membrane and the cupper current collectors are protected from the corrosive electrolyte by bipolar plates. The electrodes are in rectangular shape and squeezed to about 80% of their thickness. The porosity of the electrodes and the specific area were determined with optical measurement methods with a visual light microscope and image processing. The diffusion coefficients inside the electrodes were determined with electrochemical impedance spectroscopy. The diffusion coefficients were determined at different state of charge (SOC) to evaluate the difference in ion transport. The SOC was determined in two different ways, with UV-VIS spectroscopy, measuring the amount of Vanadium species in the electrolyte additionally to potential measurement on cell level before taking the sample. In addition to the data sheet information the commercial vanadium electrolyte was investigated with ICP-OES and the amount of vanadium and sulfuric acid was determined more precisely.
The model of the cell is a 2D implementation using the here determined parameters of geometry and kinetics of the active material inside the cell. For future purposes it is modeled as the 3D problem, accepting the additional computing time, to increase the precision of the model. The model includes the porous electrodes, the membrane and the bi-polar plates. These are all active parts of a VRFB and the bi-polar plates are included as they might have an effect of the electrochemical reactions too.
The evaluation shows that the model does represent the measured potentials the selected SOCs very well. With the confirmation of the evaluation, it is possible to withdraw information from the inside of the cell which is not accessible otherwise.
The model will be used to determine optimization potentials to simulate them before starting the cost intensive and time consuming prototyping. Another option of this model is its extension towards aging effects of the components inside the cell to give life time predictions for the application.

Figure 1
Cycle and Calendar Aging Study of Lithium-Ion Batteries Under Various Vehicle-to-Grid Scenarios
Authors: Devie Arnaud , Dubarry Matthieu 
Published: February 2020

Battery degradation is extremely sensitive to usage and chemistry. Some batteries may be markedly sensitive to temperature, to state of charge, to both, or to some other factors. This raises concerns over battery durability in the rollout of electric vehicles (EVs) in hot climate. Additionally, with the integration of more and more intermittent renewable energy power plants on the grid, there is a push to use EV batteries as energy storage systems which may stress the batteries even more. In most studies on the techno-economical impact of EVs on the grid, the battery is often viewed as a black box and therefore there is no real understanding on the actual long term impact of climate and/or vehicle-to-grid (V2G) and grid-to-vehicle (G2V) charging profiles on batteries. This work aims at assessing such impact.
Daily vehicle usage can be broken down into driving, charging and idling periods. In most cases, car batteries spend most of their time idling and it is therefore essential to understand the degradation associated with time, temperature and state of charge on top of the impact of the duty cycles. Herein, we studied the impact of driving on the cell degradation with or without V2G and G2V episodes by looking at both the calendar-induced and cycling-induced degradation. All the data was analyzed using HNEI’s unique diagnosis and prognosis tools [1-3] to forecast the degradation over the battery warranty period and beyond.
This research supports the goals of the Electric Vehicle Transportation Center.
[1] M. Dubarry, C. Truchot and B.Y. Liaw, J. Power Sources 219 (2012) 204-216
[2] M. Dubarry, A. Devie and B.Y. Liaw, J. Energy Power Sources 1(5) (2014) 242-249
[3] https://www.soest.hawaii.edu/HNEI/alawa/
Improvement of Electrochemical Property of Molecular Cluster Ion Cathode Material for Lithium Battery
Authors: Sonoyama Noriyuki , Tsukada Tetsuya , Ni Erfu 
Published: February 2020

Polyoxometalates (POM) are very famous cluster ions that can be synthesized self-assembly formation in the solution. These cluster ions behave as independent molecules and show reversible redox activity in the solution. These molecular cluster ions are expected to show different property from the usual cathode materials for lithium ion battery those are the bulk continuum ionic crystals.[1-3] In this paper, we have synthesized Anderson-type POM Na3[AlMo6O24H6] (Fig.1 ) and examined its electrochemical property as cathode materials for lithium battery. In Anderson-type POM, all [MoO6] share the edge with hetero ion [AlO6]. This covalent bond of [MoO6] with unreactive hetero ion would stabilize the structure of the reduced POM.
Anderson-type POMs were synthesized according to the reported method. [4] Obtained samples were mixed with acetylene black with the weight ratio of 1:2 using ball mill. The charge-discharge test and AC-impedance spectra measurements are performed using the coin cells at 25ºC. Lithium metal was used as anode and 1M solution of LiPF6in EC:DEC (3:7 v/v%) was used as the electrolyte. After the charge-discharge measurements, ex-situ XRD and Raman measurements were carried out under Ar atmosphere again.
NMR, FT-IR and Raman spectra of obtained samples agreed with those for reported Anderson-type POM. In Fig. 1, the discharge-charge curves for Na3AlMo6O24H6 were shown. Na3AlMo6O24H6 mixed by ball mill show large capacity over 420 mAh/g. In Fig.2, cycle stability of Na3AlMo6O24H6 was shown. The cycle stability of Na3AlMo6O24H6 was higher than the most representative POM K3PMo12O40 with Keggin type structure. 90% of the initial discharge capacity for Anderson-type POM was retained after 50 cycles, whereas that for KPM decreased steeply in the first 10 cycles. This result suggests Anderson type POM has higher stability than Keggin type POM.
In the presentation, methods for further improvement of the electrochemical property of POM will be explained.
[1] N. Sonoyama et al, J. Power Sources, 196 (2011) 6822.
[2] S. Uematsu et al, , J. Power Sources, J. Power Sources, 217, (2012)13.
[3] E. Ni et al. J Nanopart Res, 15(2013) 1732.
[4] Kenji Nomiya et al. Polyhedron, (1987) 213.

Figure 1
Anodizing of MgZn2 Phase in Sulfuric Acid: Mechanism of O2- Diffusion in Mixed (Mg,Zn)O at High Voltage
Authors: Rocca Emmanuel , Tardelli Joffrey 
Published: February 2020

The η-MgZn2 phase is an important intermetallic phase present in some galvanized coatings on steel, but also is present as strengthening phase in many aluminum alloys belonging to the 7XXX series. The objective of this work is to characterize the electrochemical behavior of MgZn2 phase in the classical electrolyte of aluminum anodizing, H2SO4 2 M.
Firstly, bulk phase was synthesized by melting pure zinc and magnesium at 700 °C during 1 hour in a furnace under argon flux and then the sample was annealed at 400 °C during 12 hours. As expected by the E-pH diagram of zinc and magnesium, the MgZn2 phase undergoes a rapid dissolution in sulfuric acid medium at open-circuit potential. The surface analyses show a classical morphology of metallic dissolution.
At high voltage (between 3V to 30 V), the dissolution of MgZn2 phase is greatly reduced and the electrochemical measurements reveal the presence of a passivation plateau. Even though the passive current density remains relatively high (around 20 mA cm-2 at 10 V), the formation of a thin layer of oxide on surface was observed by microscopic analysis on surface and metallographic cross-sections (FEG-SEM). X-ray diffraction at grazing incidence and X-ray photoelectron spectroscopy allowed us to determine the overall composition of the oxide, MgxZn1-xO.
The growth kinetic of oxide was characterized versus the voltage and the anodizing time by in-situ electrochemical impedance spectroscopy measurements at high voltage.
At low voltage (< 5 V), the growth of the anodized layer is governed the diffusion of O2- in the solid state under the electric field. Nevertheless, the growth rate is low because the apparent diffusion coefficient, determined by EIS, is low in this voltage range and the oxide dissolution is important in the electrolyte.At high voltage (> 10 V), the in-situ EIS measurements show a blocking behavior of the electrode. The growth rate is managed by the metal/oxide interface and the growth rate of oxide layer remains low in acid sulfuric medium.
In-situ electrochemical impedance constitutes an important tool to determine the conditions of anodizing and the useful anodizing range of most of metallic materials.
(Corrosion Division H. H. Uhlig Award) Electrochemical Modeling of Intergranular Corrosion and Stress-Corrosion Cracking in AA5083-H131
Authors: Kelly Robert G. 
Published: February 2020

Al-Mg alloys containing more than 3 wt. % Mg exposed to temperatures as low as 50oC for long periods of time can form b-phase (Al3Mg2) that will precipitate via heterogeneous nucleation and growth, leading to sensitization, and susceptibility to intergranular attack. The grain boundary precipitation of β-phase is dependent on Mg content, temperature, exposure time, and grain boundary characteristics, and is often practically characterized by degree of sensitization (DoS) defined by ASTM G-67, but more scientifically by β- phase grain boundary coverage. The presence of the b-phase renders the material susceptible to both intergranular corrosion (IGC) and intergranular stress-corrosion cracking (IGSCC). IGC and IGSCC penetration depend on DoS, but more directly β-phase coverage, grain orientation, temper and critically on electrochemical potential in NaCl solution. An aggressive fissure chemistry must be maintained to sustain IGC/IGSCC growth, and this maintenance depends on the dissolution properties of both α and β phases. Threshold potentials are observed for IGC in NaCl solution. The origins of both the threshold and potential dependency of IGC and IGSCC growth rates in Al-Mg alloys will be discussed in terms of the coverage of β on the grain boundaries and the electrochemical properties of the alloy phases.