bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ Characterization of Nanostructured Electrode Materials for Energy Conversion and Storage, Using Probe Beam Deflection Techniques
Authors: Barbero Cesar Alfredo , Bruno Mariano M , Coneo Rodriguez Rusbel , Balach Juan , Cotella Nelson Gustavo , Acevedo Diego Fernando 
Published: February 2020

Nanostructured conductive materials of large surface area which are important in many areas of energy conversion and storage, including supercapacitors and fuel cells. While electrochemical techniques (e.g. cyclic voltammetry) assess the charge transfer processes at the electrode interface, the ion exchange process could only be inferred. Techniques of ion exchange determination, such as the electrochemical quartz crystal microbalance (EQCM) are of difficult application to porous electrodes since it requires fixing the porous material to the oscillating crystal.
On the other hand, the techniques that monitor ion fluxes outside the electrode surface are able to study the actual ion exchange between a porous electrode and the electrolyte. Among them, Probe Beam Deflection (PBD) is a technique highly suitable to study porous electrodes.[1] The method uses a laser beam travelling parallel to the electrode surface which is refracted by the refractive index gradient associated with the flux of soluble species perpendicular to the electrode, at the center of the laser beam. Since the detection of beam position is optoelectronic, fast (ms) signals can be measured, unlike EQCM, allowing detecting transient phenomena. Since the flux is directly proportional to the surface area (like the current) the ratio of surface area to geometric pathlength (width of the electrode) assures large signal for porous electrodes.
In this report, the study of different electrode materials using Probe Beam Deflection techniques is described. After a qualitative exploration using cyclic deflectometry, a continuous mass transport model is used to quantitatively evaluate the chronodeflectometric response.[2]
First, the study of different porous glassy carbon materials is described. Then, PBD is applied to study mesoporous ordered Pt materials active in direct methanol fuel cells.[3] Finally, thin films of mesoporous oxides decorated with Au nanoparticles,[4] are investigated.
The potential of minimum charge (PMC) can be determined and compared with the value measured by AC Impedance. Besides, transient phenomena like pH changes or effects on the coupled chemical reactions inside the pores can be easily detected. Therefore, a better understanding on the mass transfer in porous electrodes is obtained.
References
1. G.G. Láng and C.A. Barbero, Laser Techniques for the Study of Electrode Processes, Springer, Berlin (2012)
2. G.A. Planes et al, Chem. Commun., 2146-2148, 2005
3. G. Garcia, et al, PCCP, 10, 6677-85, 2008
4. R. Coneo Rodriguez, et al., Sens. & Act. B-Chem., 603 – 612, 2018
Thermo-Electrochemical in-Situ Instrumentation for Smart Energy Storage
Authors: Amietszajew Tazdin , Fleming Joe , Bhagat Rohit 
Published: February 2020

Lithium-ion rechargeable cells are widely used as instant power delivery devices. High energy and power densities along with capacity retention over tens of thousands of cycles are highly beneficial compared to alternative technologies. However, recent failure incidents and constant health and safety concerns are slowing down the adoption of this technology and limiting the performance through cautious approach. In order to alleviate these issues, a better understanding of the performance and safety limits and the cells’ internal thermodynamic responses is required. Both the in-situ thermal and electrochemical mechanisms need to be carefully characterised to unlock the full performance without jeopardising safety.
This work focuses on an altogether new in-situ instrumentation methods coupling the use of a quasi-reference electrodes, optical sensing technology and miniature thermistors for supplemental internal and external temperature profiles. This methodology allows for new level of analysis, providing insight into in operando in-situ parameters of a range of cell shapes and formats. Higher reliability, shorter charging times and early fault detection can be achieved with the use of smart instrumented Li-ion cells, enabling significant advances in the battery technology.

Figure 1
Characterizing Carbon Felt Electrodes for Vanadium Redox Flow Batteries Using Differential Electrochemical Mass Spectrometry
Authors: Eifert László , Jusys Zenonas , Behm Rolf Jürgen , Zeis Roswitha 
Published: February 2020

Carbon felts are commonly used as electrode materials for vanadium redox flow batteries (VRFBs). Their physical and chemical properties strongly influence the overall cell performance. The degradation of these materials due to parasitic side reactions (carbon corrosion, oxygen and hydrogen evolution) is partially responsible for performance losses of the cell [1].
Differential electrochemical spectrometry (DEMS) has been proven to be suitable for characterizing carbon materials, mainly in the context of fuel cell research [2–4]. Recently, Taylor et al. used DEMS to calculate the Faradaic efficiency of the V3+ reduction reaction on the oxidized edge and basal surfaces of graphite discs in a model study on the activity and stability of the negative electrode in VRFBs [5].
For our experiments, we modified a thin layer flow cell DEMS setup to conduct simultaneous electrochemical and online mass spectrometric measurements on commercial carbon felt electrodes. With this setup, half-cell tests, such as cyclic voltammetry, and coulometry of the redox couples under stopped flow of the electrolyte were performed. We used different potential windows, and two types of electrolytes while monitoring potential dependent H2, O2 and CO2 formation. At oxidizing potentials, we did not observe oxygen evolution, only carbon corrosion. In the presence of vanadium, an increase in CO2 and H2 formation at high respectively low potentials was observed.
The DEMS method is capable to monitor side reactions occurring in VRFBs. Therefore, it is a useful tool to develop electrode materials, which exhibit a higher corrosion resistivity.

1. Eifert L, Banerjee R, Jusys Z, Zeis R (2018) Characterization of Carbon Felt Electrodes for Vanadium Redox Flow Batteries: Impact of Treatment Methods. J Electrochem Soc 165:A2577–A2586. doi: 10.1149/2.0531811jes
2. Colmenares LC, Wurth A, Jusys Z, Behm RJ (2009) Model study on the stability of carbon support materials under polymer electrolyte fuel cell cathode operation conditions. J Power Sources 190:14–24. doi: 10.1016/j.jpowsour.2009.01.078
3. Ashton SJ, Arenz M (2012) Comparative DEMS study on the electrochemical oxidation of carbon blacks. J Power Sources 217:392–399. doi: 10.1016/j.jpowsour.2012.06.015
4. Pérez-Rodríguez S, Sebastián D, Lázaro MJ, Pastor E (2017) Stability and catalytic properties of nanostructured carbons in electrochemical environments. J Catal 355:156–166. doi: 10.1016/j.jcat.2017.09.019
5. Taylor SM, Pătru A, Perego D, et al. (2018) Influence of Carbon Material Properties on Activity and Stability of the Negative Electrode in Vanadium Redox Flow Batteries: A Model Electrode Study. ACS Appl Energy Mater 1:acsaem.7b00273. doi: 10.1021/acsaem.7b00273
6. Eifert L, Banerjee R, Jusys Z, Zeis R (2018) Differential Electrochemical Mass Spectrometry of Carbon Felt Electrodes for Vanadium Redox Flow Batteries. ACS Appl Energy Mater 1 (12), 6714-6718 doi: 10.1021/acsaem.8b01550

Figure 1
Neutron Imaging as a Method for Quantifying Concentration Distribution within an Organic Redox Flow Battery
Authors: Forner-Cuenca Antoni , Greco Katharine Virginia , Kowalski Jeffrey A , Boillat Pierre , Brushett Fikile R. 
Published: February 2020

Redox flow batteries (RFBs) are promising rechargeable electrochemical devices for grid-scale energy storage, but further cost reductions are needed for ubiquitous adoption of this technology [1]. While recent research trends have focused on molecular discovery [2], advances in the science and engineering of electrochemical reactors can lead to cost reductions via increased power density and/or decreased component cost. Key to such efforts is deconvolution of coupled transport and kinetic processes within operating device and, to this end, imaging diagnostics, such as X-ray tomographic microscopy [3], infrared thermography [4], and electrochemiluminescence imaging [5], have been employed to visualize relevant properties (e.g., fluid distribution, temperature) in RFBs. However, obtaining quantitative property descriptions at high resolution and under representative operation conditions remains a challenge.
In this presentation, we introduce neutron radiography as an operando characterization method for RFBs which is particularly sensitivity to organic materials with high hydrogen content. To demonstrate the potential of this diagnostic tool, we characterize active species concentration distribution within a redox flow cell in a single electrolyte configuration with a nonaqueous electrolyte containing TEMPO/TEMPO+. Specifically, we employ the in-plane imaging configuration [6] to visualize concentration gradients across the flow fields, electrodes, and membrane and to correlate these profiles to cell performance via polarization and electrochemical impedance spectroscopy.

References

Darling et al., Energy & Environmental
Science, 7, 3459 (2014).

A. Kowalski et al., Current Opinion in Chemical Engineering, 13, 45 (2016).

Tariq et al., Sustainable Energy & Fuels, 2, 2068 (2018).

Tanaka et al., Journal of Energy Storage, 19, 67 (2018).

Rubio-Garcia et al., Electrochemistry Communications, 93, 128 (2018).

Boillat et al., Electrochemistry Communications, 10(4), 546 (2008).

Acknowledgments

We gratefully acknowledge the financial support of the Swiss National Science Foundation (P2EZP2_172183) and the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the United States Department of Energy.
The Effects of Thermal Gradients in Automotive Battery Packs Balancing Strategy
Authors: Vendola Emma , Marinescu Monica , Offer Gregory James 
Published: February 2020

In order to reduce current and enable fast charging, future packs will operate between 800 V and 1000 V; these high voltage ratings will be achieved by connecting a large number of cells in series [1]. Unbalance in series strings occurs even if all cells are supplied with the same amount of current, it is induced by the differences in cell State of Health (SOH) and exacerbated by temperature gradients across the pack. The focus of this study is demonstrating that temperature gradients are a major source of voltage imbalance [2]. It is suggested that, if not temperature-informed, dissipative balancing could induce further discrepancies in the amount of charge (Ah) stored in each cell and overcharge cells incorrectly, triggering degradation.
The work compares the performance of different balancing strategies applied to a string of 3 cells. During operation an automotive pack is subject to non-uniform temperatures; to experimentally reproduce this scenario isothermal boundary conditions are imposed on the cells, with cells artificially held at different temperatures. The study compares no balancing against simple top-up balancing based upon voltage limits, and more intelligent strategies based upon state-of-charge estimation with and without temperature correction.
Each of the balancing techniques are assessed in terms of the energy (Wh) and power (W) available for operation and also by the amount of dissipated energy due to balancing. It is proposed that simple top-up balancing can exacerbate charge imbalance; whilst more advanced strategies can increase useable pack energy and cycle life. The work also explores how many cycles the string can undergo before charge dissipation is necessary.
[1] S. Ahmed et al., “Enabling fast charging – A battery technology gap assessment,” J. Power Sources, vol. 367, pp. 250–262, Nov. 2017.
[2] Y. Troxler et al., “The effect of thermal gradients on the performance of lithium-ion batteries,” J. Power Sources, vol. 247, pp. 1018–1025, Feb. 2014.
Aging of Lithium Ion Battery Electrolytes – Novel Analysis Techniques for Elucidation of Potentially Hazardous Decomposition Products
Authors: Stenzel Yannick Philipp , Henschel Jonas , Winter Martin , Nowak Sascha 
Published: February 2020

In present time, energy and consequently energy storage are topics of utmost importance. With regard to the latter, the lithium ion battery (LIB) is the most promising candidate to fulfill the demanding requirements of energy storage in terms of energy density, cycling stability and safety. But, electrolytes of state-of-the-art LIBs exhibit diverse decomposition mechanisms and thus decomposition products. Hence, identification of compounds and as a result mechanistic conclusions were in focus in recent years.[1] Additionally, quantitative data of the potential hazardousness of those compounds is crucial. This importance is even more emphasized since some decomposition products show structural similarities to phosphorus-based pesticides or even worse, chemical warfare agents.
For structural elucidation of compounds, high-resolution organic mass spectrometric techniques were used as they deliver excellent sensitivity and low limits of detection. Concerning quantification, inductively coupled plasma-mass spectrometry (ICP-MS) was used due to the high structural variety of compounds and lack of commercially available analytical standards. For this purpose, a sector-field mass spectrometer (SF-MS) delivered reliable quantitative data in high resolution and in a broad linear range while still offering excellent detection limits. Thus, quantities could be assigned to the respective compounds that were identified parallel. Prior to detection, the species of interest were separated depending on their chemical characteristics. Since a large variety of compounds with different chemical properties was found, comprehensive analysis using different chromatographic techniques was adjusted accordingly for specific separation of compounds. The results were interpreted with regard to total decomposition products in electric vehicles and toxicological aspects, eventually, delivering a risk estimate of potentially hazardous compounds of LIB electrolytes.
In this study, investigation of LIB electrolytes from lab-scale and field-tested EVs are interrelated regarding variety and especially quantity of phosphorous compounds of the decomposition route of the conducting salt LiPF6.[2] Simulated abusive treatment through use of elevated temperature outside of the stability window of electrolyte components and voltages exceeding the nominal cycling range are analyzed and interrelated with extracted electrolytes of field-tested cells.
[1] S. Nowak and M. Winter, Journal of The Electrochemical Society, 2015, 162 (14), A2500-A2508.
[2] V. Kraft, W.Weber et al., RSC Advances, 2016; 6
(1), 8-17.
In Situ NMR Study on Lib Electrolytes -Tracing the Network of Reactions in a Battery-
Authors: Wiemers-Meyer Simon , Nowak Sascha , Winter Martin 
Published: February 2020

The class of lithium ion battery (LIB) electrolytes most commonly used nowadays is under investigation for at least two decades. These electrolytes, consisting of organic carbonates and LiPF6, are known to undergo not only electrochemical reactions due to their limited electrochemical stability but also chemical reactions due to their sensitivity to hydrolysis. The interplay of chemical and electrochemical reactions as well as their interactions with cathodes, anodes and their surfaces are not yet fully clarified. To study these reactions different analytical techniques can be applied. This usually requires an extraction of the electrolyte from the battery involving a high risk of sample alterations due to volatile and highly reactive substances.
To overcome this issue a battery cell set-up for in situ NMR measurements of liquid electrolytes has been developed.1 It enables non-invasive investigations providing molecular information from the inside of an intact battery. The cylindrical battery cell consists of two electrodes in a heat-sealed polymer tube that is small enough to be placed in a standard 5 mm NMR glass tube (see figure). To ensure gas tightness the NMR glass tubes are sealed with epoxy resin. All the common electrode materials including transition metal oxides, graphite as well as lithium metal can be applied as active electrode materials.
Electrochemical tests demonstrate a sufficient rate performance and a good cycling stability of the in situ cells. NMR measurements of the cells provide well-resolved spectra not distorted by the solid battery components. Furthermore, it can be shown that a loss equal or less than 0.1 % of the working electrode capacity by a one-electron reaction forming hydrogen or fluorine containing compounds is sufficient to reach the limit of detection (capacity: 1 to 6 mA h, 400 MHz NMR spectrometer). Hence, the sensitivity of this method is considered high enough to detect any significant electrochemical formation of soluble compounds exhibiting clear 1H or 19F NMR signals.
The results so far show that the in situ cells enable investigations on the passivating properties of the solid electrolyte interphase on the anode (SEI) by monitoring the formation of compounds electrochemically formed on the anode. Furthermore, they revealed temperature and potential dependent fluorination reactions of electrolyte solvents on the cathode surface. In addition, the measurements provide insight into exchange reactions of the cathode material with the electrolyte probably influencing the SEI. NMR spectroscopy also offers a way to investigate transition metal dissolution from the cathode active material into the electrolyte. Although paramagnetic species, e.g., Mn2+, Ni2+ and Co2+ cannot be detected directly by NMR, they have a strong and detectable impact on the relaxation of the spin magnetization of nuclei in their proximity.
1) S. Wiemers-Meyer, M. Winter and S. Nowak, Phys. Chem.
Chem. Phys, 2017, 19, 4962-4966.

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(Invited) Interfacial Resistance at Atomically-Engineered Interfaces in Solid-State Batteries
Authors: Hitosugi Taro 
Published: February 2020

Solid-state Li batteries are promising energy-storage devices owing to their high-energy densities with improved safety. However, the large interfacial resistance at the interface of solid-electrolytes and electrodes hinders the development of the solid-state Li batteries.
Our group has been investigating surfaces and interfaces of transition-metal oxides, such as SrTiO3, LaAlO3/SrTiO3, SrVO3, La0.7Ca0.3MnO3, and LiTi2O4, using epitaxial thin-film deposition technology and scanning tunneling microscopy [1-7].
Accordingly, we introduced the above knowledge of the atomic-scale investigation of oxide surfaces into battery research. We succeeded in fabricating the interface resistance below 5 Ωcm2(Li3PO4/LiCoO2interface [8,9],Li3PO4/LiNi0.5Mn1.5O4interface [10]); the value is smaller than that of liquid-electrolyte-based Li-ion batteries. These studies strongly encourage solid-state Li battery research, by demonstrating a very low interface resistance leading to fast charging and discharging.

References

[1] R. Shimizu, K. Iwaya, T. Ohsawa, S. Shiraki, T. Hasegawa, T. Hashizume, and T. Hitosugi,
ACS Nano
5, 7967 (2011).
[2] K. Iwaya, T. Ogawa, T. Minato, K. Miyoshi, J. Takeuchi, A. Kuwabara, H. Moriwake, Y. Kim, and T. Hitosugi,
Phys. Rev. Lett.
111, 126104 (2013).
[3] T. Ohsawa, R. Shimizu, K. Iwaya, and T. Hitosugi,
ACS Nano
8, 2223 (2014).
[4] I. Hamada, R. Shimizu, T. Ohsawa, K. Iwaya, T. Hashizume, M. Tsukada, K. Akagi, and T. Hitosugi,
J. Am. Chem. Soc.
136, 17201 (2014).
[5] T. Ohsawa, M. Saito, I. Hamada, R. Shimizu, K. Iwaya, S. Shiraki, Z. Wang, Y. Ikuhara, and T. Hitosugi,
ACS Nano
9, 8766 (2015).
[6] Y. Okada, S.-Y. Shiau, T.-R. Chang, G. Chang, M. Kobayashi, R. Shimizu, H.-T. Jeng, S. Shiraki, H. Kumigashira, A. Bansil, H. Lin, and T. Hitosugi,
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119, 086801 (2017).
[7] Y. Okada, Y. Ando, R. Shimizu, E. Minamitani, S. Shiraki, S. Watanabe, and T. Hitosugi,
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8, 15975 (2017).
[8] M. Haruta, S. Shiraki, T. Suzuki, A. Kumatani, T. Ohsawa, Y. Takagi, R. Shimizu, and T. Hitosugi,
Nano Lett.
15, 1498–1502 (2015).
[9] S. Shiraki, T. Shirasawa, T. Suzuki, H. Kawasoko, R. Shimizu, and T. Hitosugi,
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10, 41732–41737 (2018).
[10]H. Kawasoko, S. Shiraki, T. Suzuki, R. Shimizu, and T. Hitosugi,
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Direct Measurement of Enhanced Ion Conductivity at an Ionic Liquid Electrolyte (ILE)/SiO2 Interface with Interdigitated Electrode Array
Authors: Put Brecht , Hollevoet Simon , Sagara Akihiko , Labyedh Nouha , Clerckx Nick , Hendrickx Nathalie , Kaneko Yukihiro , Arase Hidekazu , Mees Maarten J. , Vereecken Philippe M. 
Published: February 2020

Recently, our group reported a novel solid-state electrolyte material which is constituted of a nano-porous SiO2 monolith and an ionic liquid electrolyte (ILE) which occupies the pores. The unique feature of this solid nano-composite electrolyte (nano-SCE) is its ion conductivity which is higher than that of the ILE itself [1]. Here, we report a direct measurement of this enhanced ion conductivity by measuring the ion conductivity of a thin-film ILE on a planar SiO2 substrate.
The enhanced ion conductivity is directly measured with interdigitated electrode arrays deposited on a planar SiO2 substrate, as shown in Figure 1. By depositing a thin-film ILE film on these electrodes, the impedance response of the ILE/SiO2 interface could be measured by impedance spectroscopy (IS). The ion conductivity on the ILE/SiO2 interface could subsequently be quantified by analysis of the equivalent circuit model and by measuring the ILE film thickness.
The ILE film thickness is scaled down to the nanometer regime. This is the first time that such thin ILE films could be deposited using liquid processing techniques. The enhanced ion conductivity is revealed when the ILE film thickness is reduced to 20 nm thicknesses and below. The ion conductivity of the ILE films with a thickness around 80 nm have a similar conductivity compared to the bulk ILE.
Enhanced ion conductivity along interfaces has been observed before and is typically referred to as heterogenous doping [2]. The mechanism that governs the enhanced conductivity in the nano-SCE are similar to those described by heterogenous doping. However, the ion conductivities measured in this work are many times higher compared to those reported before.
In conclusion, for the first time ILE thin-films with thicknesses in the nanometer regime are deposited with liquid processing. Moreover, the ion conductivity at the ILE/SiO2 interface could be quantified and showed an increased conductivity compared to the bulk ILE value.
References
[1] P. M. Vereecken, X. Chen, K. B. Gandrud, B. Put, A. Sagara, M. Murata, M. Tomiyama, Y. Kaneko, M. Shimada, J. Steele, M. Roeffaers, M. Debucquoy and M. J. Mees, "Mechanism Analysis of Enhanced Li-Ion Conductivity in Mesoporous Silica-Based Solid Nano-Composite Electrolytes", ECS Meeting Abstracts, vol. 470, pp. MA2018-02, 2018.
[2] N.F. Uvarov, “Composite Solid Electrolytes: Recent Advances and Design Strategies”, J. Solid State Electrochem., 15 (2), 367–389, 2011.

Figure 1