bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Solid State Battery Cells for in Operandi Diffusion Measurements Using µ+sr Spectroscopy
Authors: Corr Serena
Published: February 2020

Solid state lithium ion batteries (SSBs) have been widely tipped to revolutionise energy storage technology. The combination of increased safety, longer lifetime, larger electrochemical potential window and higher energy density offered has led to sustained global research into their development. One important aspect of that development is the dynamics of ion diffusion, particularly through the bulk solid electrolyte but also at the electrode/electrolyte interface. Ion diffusion rates can limit how fast batteries can be charged/discharged, with charge movement across the electrode/electrolyte boundary especially key in SSBs, which can experience poor interfacial contact. An increased understanding of microscopic level ion behaviour at these boundaries will prove valuable, but has so far been elusive with techniques such as NMR and impedance spectroscopy yielding inconsistent results.1,2

Muon spin relaxation (µ+SR) spectroscopy is a relatively new technique used to investigate Li+ migration mechanisms, using spin-polarised positive muons created using a synchrotron. The muons can be controlled to stop at any point within a battery, acting as an atomic scale probe of charge movement in a particular area within the crystal structure. This occurs as an implanted muon’s spin is perturbed by the magnetic field of nearby diffusing ions. After an average lifetime of 2.2 µs the muon will decay into a positron, emitted preferentially along the direction of the muon spin at the instant of decay. Detection of the asymmetry of emitted positrons gives a time evolution of the muon ensemble’s spin polarisation, yielding information on ion diffusion dynamics and activation energies. µ+SR has been proven a successful technique to study in situ batteries, producing accurate measurements that are consistent with first-principle calculations.2,3 This research will focus on the study of the promising solid-state battery electrolyte material Al-doped LLZO (Li7La3Zr2O12), using µ+SR spectroscopy as a reliable and reproducible probe. The anode and cathode materials used will be Li4Ti5O12 and LiCoO2 to complete the cell. This cell will be tested in situ from room temperature to around 80ºC on the EMU beamline at ISIS Pulsed Neutron and Muon Source. Any insights gained will be translated back to design principles to optimise battery performance.

Power Source, 2014, 268, 153–162

Mater. Chem. A, 2017, 5, 8653

Mater. Chem. A, 2016, 4, 1729

Phys. Scr., 2013, 88, 068509
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.

Figure 1
In-situ Synchrotron X-ray Powder Diffraction Characterisation of Cu6Sn5 Lithium-ion Battery Anodes
Authors: Tan Xin Fu , Gu Qinfen , McDonald Stuart D. , Matsumura Syo , Nogita Kazuhiro
Published: February 2020

Sn-based anodes have been widely studied for applications in lithium-ion batteries due to their superior storage capacities. However, the large volume changes during lithiation and delithiation often result in poor cyclic performances. Intermetallic compounds (IMCs) combining Sn with an element that does not react with lithium are commonly used to reduce the stresses in these anodes. One such example, the IMC Cu6Sn5, has been proven to improve the cyclic performance of Sn as an anode. Sn-based anodes also have lithiation voltages around 0.4 V vs. Li/Li+, making them less prone to lithium dendrite growth and therefore intrinsically safer. This work investigates the lithiation and delithiation mechanisms of a Cu6Sn5 anode fabricated via direct growth of the Cu6Sn5 IMCs on the Cu current collector by melt-solid contact. In-situ synchrotron X-ray powder diffraction revealed the “real-time” crystallographic changes of the anode during the lithiation and delithiation processes, which are confirmed by high-voltage transmission electron microscopy. The study shows a reversible two-step reaction during cycling, and highlights the differences in the reaction mechanisms at higher lithiation/delithiation rates than those reported in the published literature.

Figure 1
(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,
Phys. Rev. Lett.
119, 086801 (2017).

[7] Y. Okada, Y. Ando, R. Shimizu, E. Minamitani, S. Shiraki, S. Watanabe, and T. Hitosugi,
Nature Commun.
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,
ACS Appl. Mater. Interfaces
10, 41732–41737 (2018).

[10]H. Kawasoko, S. Shiraki, T. Suzuki, R. Shimizu, and T. Hitosugi,
ACS Appl. Mater. Interfaces
10, 27498 (2018).
Plasma-Treated, Nitrogen-Doped Nanoporous Carbon Cloth for High-Performance Supercapacitors Applications
Authors: Chodankar Nilesh R , Ji Su-Hyeon , Kim Do-Heyoung
Published: February 2020

Commonly used energy storage devices are majorly based on the commercial carbon cloth (CC) as a current collector due to its special features including ultra-low weights, three-dimensional (3D) structures, higher electrical conductivity with excellent porosities for the ion diffusion process. However, the poor compatibility and hydrophobic nature of the CC with the precursor solution and electrolyte is limiting the resultant electrochemical performance of the energy storage devices. To overcome this issue, in present work, we have developed the single step, facial nitrogen plasma method to induce nanostructuring over the CC, thereby significantly increasing the wettability and surface area of the CC, which both favourable for the facial electrochemical reactions. Morever, the plasma treatment induces the nitrogen doping on the surface of the CC allowed more electroactive species for electrochemical reactions. As a result, the nitrogen plasma treated CC (NCC) electrode shows excellent electrochemical feature for the supercapacitor application in the conventional potassium hydroxide (KOH) electrolyte. The NCC shows the highest specific capacitance of the 741 mF/cm2 at a current density of 0.5 mA/cm2, which is much higher than that of the untreated carbon cloth. In addition to this, the NCC shows the excellent cycling stability for 5000 charge-discharge cycles without any loss which represent the best capabilities of the nitrogen-plasma process for CC functionalization. The presented innovative approach of plasma process for the functionalization of carbon cloth may offer the new way to design and develop highly efficient carbon-based electrodes for supercapacitor applications.
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
Ambient Pressure XPS Studies of Liquid Solid Interfaces in Batteries
Authors: Edström Kristina , Maibach Julia , Källquist Ida , Lindgren Fredrik , Hahlin Maria
Published: February 2020

Liquid solid interfaces in batteries are not trivial to study in a realistic and detailed way. Often interfaces of cathodes or anodes in cycled batteries, are studied post mortem and at ultra-high vacuum to really determine the chemical composition in the outermost electrode/electrolyte layer. It is, therefore, a need to develop new characterisation methods which can allow for the study of dynamic reactions taking place at interfaces as a function of battery cycling. In this presentation, we will describe our attempts to develop electrochemical cells that can be used at ambient pressure (25 mbar). The cells are dependent on photoelectron spectrometers (PES) that have differential pumping systems and where the samples can be protected but still transferred without intermediate ultrahigh vacuum step of the load lock. These spectrometer exist now at synchrotron facilities but also as in house equipment. The challenge is how the electrochemical cell should be designed and how to study the liquid solid interfaces in detail and especially when the liquids are organic volatile solvents.

Our first results will be presented as three examples. The first example is a comparison of the solid electrolyte interphase (SEI) on a silicon surface measured at ultrahigh vacuum with one measured at ambient pressure. Questions such as: will the chemical composition of the SEI be considerably different at ambient pressure and will the resolution of the analysis be high enough to reveal any differences in the chemical composition? The second example is a study of the surface of a droplet of a lithium-ion battery electrolyte on a metallic lithium substrate characterised at 2 mbar and 0.2 mbar, respectively, and studied with ambient pressure PES. The study was performed on the beam-line Hippie at MAXIV laboratory. Our third result is the cycling of an electrode with an electrolytes within electrochemical cell in the Hippie spectrometer. The implication of all these three studies is that a step has been taken to more realistic studies of surface reactions in a LIB context. The experimental challenges are also detailed in the presentation.
Fabrication of Super Hydrophobic Gas Diffusion Layers
Authors: Thumbarathy Deepashree Sudhir , Das Prodip K
Published: February 2020

Gas diffusion layer (GDL) plays a significant role in water management and heat removal within the polymer electrolyte fuel cells (PEFCs). When the GDL is flooded with liquid water, PEFC undergoes mass transport losses due to pore blockage by water which leads to decreased cell performance. For this purpose, the fabrication of selective wetting pattern by spray coating on the GDL surface is reported in this study. The present study will investigate the surface morphology of the GDL determined by its pore geometry and hydrophobicity which can control the water transport in PEFCs. Commercial GDLs were selected as a substrate. Two different monomers were used and their emulsions of required concentration were spray coated and polymerised to achieve the hydrophobic coatings. Regardless to monomer’s viscosity, super hydrophobic coatings on Commercial GDLs were obtained via spray coating with a contact angle of 1590 or higher, while the base surface’s contact angle was in the range of 1000.

The fabricated GDLs were further analysed by means of sliding angles and scanning electron microscopy. Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed the successful introduction of the functional groups in both the coatings. Pore size distribution and adhesion forces measurement were used to investigate the water droplet transport on the coated GDLs. In this presentation, the results of our study will be discussed with the aim of highlighting how these results will benefit the water management of next generation high-power PEFCs.
Conducting Polymer PEDOT As Electrocatalysts and Electrode Materials in Hydroquinone Fuel Cell
Authors: Crispin Xavier , Che Canyan , Vagin Mikhail , Wijeratne Kosala , Zhao Dan , Warczak Magdalena , Jonsson Magnus P
Published: February 2020

Here, we report that the aromatic alcohols obtained from lignin depolymerization can be used as fuel in high power density electrical power sources. Our study shows that the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT), fabricated from abundant elements via low temperature synthesis, enables efficient, direct and reversible chemical-to-electrical energy conversion of aromatic alcohols such as lignin residues in aqueous media. We propose a material operation principle related to the relatively high molecular diffusion and ionic conductivity within the conducting polymer matrix, ensuring efficient uptake of protons in the course of proton-coupled electron transfers (PCET) between organic molecules. We demonstrate the PCET by a first direct quinone fuel cell (DQFC), which converts chemical energy stored in benzenediols recovered from lignin into electricity, without CO2 emission.
On the Relation between Ionic Transport Properties and Viscoelastic Response of Solid Polymer Electrolytes
Authors: Grazioli Davide , Panteghini Andrea , Simone Angelo
Published: February 2020

The need for high energy density and micro-scaled power sources is pushing researchers and industries towards the development of three-dimensional architecture micro-batteries and structural batteries. In this perspective, solid polymer electrolytes (SPEs) represents an appealing alternative to conventional (liquid) electrolyte. Due to their intrinsic multifunctionality, SPEs can serve as the structural matrix of fiber-reinforced composites and as the electrolyte of a battery. In addition, the improved safety features, excellent flexibility and processability, allow to cast SPEs into complex three-dimensional geometries without leakage.

Experimental studies indicate that mechanical and electrochemical responses of SPEs are related. In particular, the segmental motion of the polymer molecules is crucial for both the viscoelastic properties and the ionic conductivity of the material. A limited polymer segmental motion generally results in a stiffer mechanical response and a reduced ionic conductivity, while the opposite applies when the polymer segmental motion is enhanced. This results in a trade-off between mechanical and electrical performance from a material design point of view [1] and a deformation-dependent ionic transport mechanism in the polymer during service [2].

In this work we present a coupled electrochemo-mechanical model for SPEs. The polymer is modeled as a solid through which the transport of multiple charged species takes place and is described in terms of molar concentration of ions, electric potential and displacement field. Since the molar concentration of ions in the SPE is notably non-uniform during battery service [3,4], the model explicitly accounts for concentration-dependent diffusion coefficients and viscoelastic properties. Results of a finite element method formulation are presented, and the impact of the viscoelastic mechanical behavior on the overall battery response is discussed.

References:

[1] Asp, L.E. and Greenhalgh, E.S., "Structural power composites", Composites Science and Technology, 101, pages 41-46 (2014).

[2] Kelly, T., Ghadi, B.M., Berg, S. and Ardebili, H., "In situ study of strain-dependent ion conductivity of stretchable polyethylene oxide electrolyte", Scientific Reports, 6, page 20128 (2016).

[3] Grazioli, D., Verners, O., Zadin, V., Brandell, D. and Simone A., "Electrochemical-mechanical modeling of solid polymer electrolytes: Impact of mechanical stresses on Li-ion battery performance", Electrochimica Acta, 296, pages 1122-1141 (2019).

[4] Grazioli, D., Zadin, V., Brandell, D. and Simone A., "Electrochemical-mechanical modeling of solid polymer electrolytes: Stress development and non-uniform electric current density in trench geometry microbatteries", Electrochimica Acta, 296, pages 1142-1162 (2019).
(Invited) Modeling the Defect Chemistry, Transport Properties, and Stability of Antiperovskite Materials
Authors: Ciucci Francesco
Published: February 2020

Solid-state electrolytes with fast lithium conduction are the core of the all-solid-state Li battery technology. By substituting the organic electrolyte with a piece of non-flammable ceramic material, we can achieve better safety, higher specific capacity, and a higher energy density. To date, the major bottleneck for this technology is the slow Li diffusion in the solid-state electrolyte and the interfacial incompatibility between the electrolyte and electrodes. To resolve these issues, several families of fast ionic conductors have been developed. The understanding of Li diffusion in these materials is essential to the development of novel family fast ionic conductors. To this end, atomistic modeling provides us with a unique tool to obtain comprehensive information on the atom motion, which is difficult to access with experimental techniques. In this talk, we showcase our group’s atomistic simulations regarding a novel family of superionic conductors, Li-rich anti-perovskites (LiRAPs)

LiRAPs are a promising family of solid electrolytes, which exhibit ionic conductivities above 10-3 S cm-1 at room temperature, among the highest reported values to date. We first investigated the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using DFT calculations and classical MD simulations [1]. We also studied the phase, interfacial, and voltage stability of these materials [2] with DFT, showing good agreement with experiments. Analogous simulations were also carried out for Na-rich anti-perovskites [3].

References:

[1] Z Lu, C Chen, ZM Baiyee, X Chen, C Niu, F Ciucci. Defect chemistry and lithium transport in Li3OCl anti-perovskite superionic conductors. Physical Chemistry Chemical Physics 17 (48), 32547-32555 (2015)

[2] Z Lu, F Ciucci. Anti-perovskite cathodes for lithium batteries. Journal of Material Chemistry A, 6, 5185-5192 (2018)

[3] TH Wan, Z Lu, F Ciucci. A first principle study of the phase stability, ion transport and substitution strategy for highly ionic conductive sodium antiperovskite as a solid electrolyte for sodium ion batteries. Journal of Power Sources, 390, 61-70 (2018)
Classical and Quantum Analysis of Lithium Anodes in Nanobattery Models
Authors: Seminario Jorge M. , Galvez-Aranda Diego Eduardo , Ponce Victor H , Selis Luis
Published: February 2020

We report our studies of lithium-metal anodes as part of a nanobattery with the goal of improving conditions under which the anode material can be successfully used. This work is performed using multiscale classical and quantum mechanical calculations. Specifically, we use the classical and quantum molecular dynamics atomistic simulations with liquid and solid electrolytes of different sizes. Thus, in this effort in progress, we are focusing on the electrical properties such as polarization conductivity as well as on mechanical and chemical properties such as swelling, alloying, amorphization and speciation on the anode material and in its solid-electrolyte interphase (SEI), during the first charging cycles. The nanobattery includes most of the important components of a real battery such as the cathode, the electrolyte solution (solid or liquid), the anode, and the current collectors. External electric fields are applied under classical and quantum regimes to emulate the charging process causing the migration of the Li-ions from the cathode, drifting through the electrolyte to finally get into the anode. We immediately observed during charging of the nanobattery, how some other anodes change gradually producing cracks of the SEI and then dendrites. We obtained the drift velocity of the Li-ions during the amorphization of the anodes as the original volume of the anode increases. Our nanobattery model can be used to study the mechanisms taking place at the electrolyte and electrodes interfaces, and especially for guidance, and discovery of new materials. Our results are helping us to understand the mechanics and chemistry of future batteries, specially to prevent undesirable effects such as the cracking of the anode and dendrite formation.
Physical Properties, Electrochemical Stabilities and Molecular Dynamics Study of Novel Ionic Liquids Based Electrolytes for Electrochemical Application
Authors: Hachicha Rahma , Zarrougui Ramzi , Le Vot Steven , Fontaine Olivier , Favier Frederic
Published: February 2020

A series of novel ionic liquids (ILs) based on N-allyl-N,N-dimethylethylammonium (N112A
+) are synthesized and characterized. Their physical properties and electrochemical stabilities are investigated and discussed toward the anion constituents. Herein, four anions are studied including one non-fluorinated and planar structured anion (DCA-) and three fluorinated anions (TFSI-, OTf-, TFA-). The experimental properties are compared to those predicted by molecular DFT dynamics simulations. All salts were found to be low melting compounds, while being all-liquid at room temperature. N112A-TFSI is found to be the most thermally stable (T
d = 329°C) while N112A-TFA is the least stable (Td = 158°C). The ILs transport properties have been determined versus temperature and discussed using the ionicity and Angell's fragility, concepts. Among the good and fragile prepared ILs, N112A –DCA exhibits outstanding transport properties in terms of low dynamic viscosity (19.97 mPa.s) and high ionic conductivity (19.20 mS.cm−1) at 298 K. These suitable properties are explained, from DFT computational calculations, by the lower intermolecular interactions of ion-pairs in N112A –DCA, and quantified by the decreased value of dispersion ion-pairs interaction energy (-6 kJ.mol-1) compared to the others ones. The ILs electrochemical stability window (ESW) seems strongly affected by the cation structure, while their values are found to decreases in the following order N112A -TFSI (4.40 V) > N112A-OTf (3.80 V) > N112A-DCA (3.00 V) > N112A-TFA (2.18 V). Taking into account of the most likely oxidation and reduction reactions, these trends were discuss and validated by the SMD calculation model. The experimental values of ESWs are also very close to the predicted ones. Overall, the results show that, these ILs are suitable as electrolytes for electrochemical devices as battery systems and supercapacitors.
New Electrode Materials for Sodium Ion Batteries
Authors: Munnangi Anji Reddy , Maria Joseph Helen , Fichtner Maximilian , Euchner Holger
Published: February 2020

Sodium-ion batteries (SIBs) are evolving as a low-cost alternative to the state-of-the-art lithium-ion batteries (LIBs). Elementary properties of sodium, high abundance and low cost associated with sodium precursors made it a realistic alternative to lithium-ion chemistry [1, 2]. Research activities on SIBs are growing worldwide and still require a great deal of basic research. Currently, the research on SIBs is focused on the development of new cathode and anode materials or combinations with improved properties such as high energy density, sustainability, and safety.

Sodium insertion in hard carbon is strongly debated, and a full and consistent picture of the underlying mechanism is still missing. By combining in-situ Raman spectra obtained during sodium insertion in hard carbon with detailed ab initio studies, for the first time we provide a complete description of the Na insertion process in hard carbon [3]. On the cathode side, we propose weberite-type sodium metal fluorides (SMF), a new class of high voltage and high energy density materials which are so far unexplored as cathode materials for SIBs [4]. Weberite-type is highly favorable for sodium-containing transition metal fluorides, with a large variety of transition metal combinations (M, M’) adopting the corresponding Na2MM’F7 structure. A series of known and hypothetical compounds with weberite-type structure were computationally investigated to evaluate their potential as cathode materials for SIBs. Weberite-type SMFs show quasi-three-dimensional pathways for Na+ diffusion with surprisingly low activation barriers. The high energy density combined with low diffusion barriers for Na+ makes this type of compounds promising candidates for cathode materials in SIBs. We also present the synthesis and electrochemical properties of new sodium vanadium oxy phosphate (NaVOP), Na2+xV3P2O13 (0 ≤ x ≤ 2). NaVOP shows a reversible capacity of 150 mAh g-1 at an average voltage of 2.5 V vs. Na/Na+, with high cycling stability [5]. The post-structural analysis shows Na2+xV3P2O13 (0 ≤ x ≤ 2) is structurally stable over a wide range of sodium extraction and reinsertion demonstrating its potential as cathode material for SIBs.

References:

D. Slater, D. Kim, E. Lee, C. S. Johnson, Adv. Funct. Mater. 2013, 23, 947–958.

Yabuuchi, K. Kubota, M. Dahbi, S. Komaba, Chem. Rev. 2014, 114 (23), 11636–11682.

Anji Reddy, M. Helen, A. Groß, M. Fichtner, H. Euchner, ACS Energy Lett., 2018, 3, 2851–2857.

Euchner, O. Clemens, M. Anji Reddy, submitted.

Anji Reddy, H. Euchner, R. Witter, O. Clemens, J. Mater.
Chem. A, 2018,
6
, 6947–6958.
Electrochemical Performance of Hard Carbon Anode in Moderately Concentrated Electrolytes
Authors: Patra Jagabandhu , Chang Jeng-Kuei
Published: February 2020

Hard carbon (HC), probably the most potential anode for sodium-ion batteries, currently encounters three major obstacles, which are low first-cycle coulombic efficiency, unsatisfactory charge–discharge kinetics, and insufficient cyclic stability. Our developed electrolyte can effectively improve these properties. The concept of using moderately concentrated electrolyte is proposed to deal with the limitations of high cost, low conductivity, and poor viscosity (or wettability) of superconcentrated electrolytes. The crucial roles of ethylene carbonate in the moderately concentrated electrolyte are explored in this study. With the formation of well-balanced robust inorganic–organic solid–electrolyte interphase, the first-cycle as well as steady-state coulombic efficiency of the HC electrode significantly improved to 85% and >99.9%, respectively. This electrolyte significantly improved the charge−discharge capacities at high current rates. Furthermore, after 500 sodiation−desodiation cycles, 95% of the initial capacity can be maintained. The proposed electrolyte design strategies are expected to be applicable to other battery electrodes to boost their energy-storage performance.
(Invited) Taking a Closer Look at SEI Chemistry
Authors: Xu Kang C.
Published: February 2020

Interphases enables the electrodes to operate at potentials beyond what thermodynamic stability limits of non-aqueous electrolytes would allow. The most prominent example of interphases is perhaps solid-electrolyte-interphase (SEI) on graphitic anodes in Li-ion batteries, which ensures the reversibility of Li-ion intercalation chemistries. In typical electrolytes, chemical building blocks of SEI mainly come from solvents decomposition products, and, although we often acknowledge that many aspects of SEI remains unknown, we thought we at least have establish the following foundation beyond doubt: (1) semi-carbonates from the single-electron reduction of carbonate solvents constitutes the major portion of SEI; (2) the formation of SEI is irreversible; and (3) SEI is ionic conductor and electron insulator. However, when taking a closer look at the “olde SEI” using a series of new techniques, we found some of those principles might need to be re-written.

In this work, I will summarize the newest understanding of this “least understood” component in Li-ion battery that were achieved in my own group and my collaborators.
A Study of Practical Operating Challenges in Alkaline Electrolyte for Rechargeable Zinc-Air Batteries
Authors: Sun Wei , Zhang Mengyi , Winter Martin , Bieker Peter
Published: February 2020

As one of the proposed post lithium-ion battery technologies, metal-air batteries have received revived interest recently. Among the different types of metal-air batteries, rechargeable zinc-air battery (RZAB) is a promising electrochemical energy storage device with the advantages of high theoretical energy density of 1086 Wh kg-1, high abundance, low toxicity and intrinsic safety.1 However, current RZAB still suffer from poor energy efficiency and cycle life, owing mainly to the zinc-anodes, electrolytes, and air-cathodes. To improve the low energy efficiency, many efforts have been made to promote both of the sluggish oxygen reduction/evolution reactions in the air-cathodes by engineering bifunctional catalyst materials with high reactivity. Although significant progress has been made in developing suitable catalyst materials for the air-cathode, many technical challenges still remain in electrolyte to achieve the long cycle life while maintaining high performance.

Aqueous electrolytes, predominantly alkaline electrolytes, have been adopted by the RZAB system since its birth. Potassium hydrogen (KOH) is the most commonly used alkaline electrolyte because of its high ionic conductivity, high activity for both the zinc and air electrodes as well as good low temperature performance.2 Despite its desirable properties, the usage of KOH in RZAB raises several technical problems: i) zinc dendrite formation, shape change, surface passivation from complicated reaction between zinc and OH- as well as the dissolution and migration of Zn(OH)4
2-; ii) corrosion of the carbon-based air cathode in concentrated alkaline electrolyte; iii) formation of insoluble K2CO3 arising from the reaction of aerial CO2 with KOH; iv) reduced cell shelf due to the high corrosive ability of concentrated alkaline electrolyte to the stainless steel used in the experimental cell component.

In this work, specific attention is given to the obstacles caused by the alkaline electrolytes with the focus on the fundamental understanding of zinc-anode reaction mechanisms, carbonization of electrolyte as well as the precipitation of carbonates on the air cathode. Furthermore, the effects of the practical operating conditions on battery performance and durability are discussed, including the experimental cell configuration for RZAB as well as the contaminants commonly encountered in ambient air (e.g. carbon dioxide). The approaches to overcome the challenges are also presented and analyzed for facilitating further research and development of the electrolyte for RZAB.

Reference

Li, Y.; Dai, H., Recent advances in zinc-air batteries. Chemical Society reviews
2014,
43 (15), 5257-75.

R. Mainar, A.; Leonet, O.; Bengoechea, M.; Boyano, I.; de Meatza, I.; Kvasha, A.; Guerfi, A.; Alberto Blázquez, J., Alkaline aqueous electrolytes for secondary zinc-air batteries: an overview. International Journal of Energy Research
2016,
40 (8), 1032-1049.
Practical Limitations Associated with Metallic Magnesium Sulphur Batteries
Authors: Salama Michael , Attias Ran , Gofer Yosef , Aurbach Doron
Published: February 2020

Rechargeable magnesium batteries (RMBs) have attracted a lot of attention in recent decades due to the theoretical properties of these systems in terms of energy density, safety, and price. Nevertheless, to date, fully rechargeable magnesium battery prototypes with sufficient longevity and reversibility were realized only with low voltage and low capacity intercalation cathodes. The community is therefore actively looking for high-capacity cathodes that can work with metallic magnesium anodes in viable RMB systems. One of the most promising cathode materials, in terms of very high theoretical specific capacity is sulfur. A number of recent works studied the electrochemical performances of rechargeable sulfur cathodes in RMB, with success to some extent on the cathode side. Nevertheless, the formation of soluble polysulfide’s during discharge affects strongly the behavior of the anode side. we are focusing on soluble polysulfide impact on Mg–S electrochemical systems. We carefully designed herein conditions that mimic the Mg–S battery prototypes containing balanced Mg and elemental sulfur electrodes. Under these conditions, we extensively studied the Mg anode behavior. The study shows that when elemental sulfur cathodes are discharged in the Mg–S cells containing electrolyte solutions in which Mg anodes behave reversibly, the polysulfide species thus formed migrate to the anode and eventually fully passivate it by the formation of very stable surface layers.