bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Enhanced Raman Microscopy in the Study of Li-Ion and Li-Air Battery Interfaces
Authors: Hardwick Laurence J , Aldous Iain , Cabo-Fernandez Laura
Published: February 2020

Surface layers on lithium battery electrodes play a vital role in affecting battery performance, ageing mechanics and safety. Particularly, the solid electrolyte interphase (SEI), which is a protecting layer formed on the negative electrode of lithium-ion batteries as a result of electrolyte decomposition, significantly impacts upon irreversible charge “loss”, rate capability, cyclability, exfoliation of graphite and safety.

The investigation of surface layer formation is also important in the understanding of the operation of the lithium-oxygen battery. The non-aqueous lithium-oxygen cell is one of a host of emerging opportunities available for enhanced energy storage [1]. Unlike a conventional battery where the reagents are contained within the cell, the lithium-oxygen cell uses dioxygen from the atmosphere to electrochemically form the discharge product lithium peroxide. Degrees of reversible oxidation and formation of lithium peroxide has been demonstrated in a number of non-aqueous electrolyte classes, mostly notably in dimethysulfoxide based electrolytes [2], thus making the lithium-oxygen cell a potential energy storage device.

The design and optimisation of techniques based on both surface-enhanced Raman spectroscopy (SERS) and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) for ultra-sensitive analysis will be presented in the study the formation and composition of interfaces on lithium battery electrode materials. SHINERS, first reported by Prof. Tian and his co-workers [3] provides, as does SERS, an ultra-sensitive technique for understanding the formation and composition of interphases/ passivation layers on electrode materials and is considered to be a powerful technique for in situ surface analysis. The highest enhancement of Raman scattering using SHINERS appears at the junction between the particles and substrate as hot spots with magnitudes of up to 4x108 fold. Raman signals can be greatly enhanced by surface plasmon resonance generated on the surface of gold or silver nanoparticles. In SHINERS, the gold nanoparticles are coated with ultrathin silica or alumina layer. The inert shell is expected to be thin, uniform, fully enclosed and optically transparent so that it can retain the surface enhancement and ensure that there is no direct contact between the probed substance and the gold core. The shell-isolated nanoparticles are then spread onto the electrode surface and assembled into an in situ Raman electrochemical cell.

The poster will present our groups recent results of the spectro-electrochemistry studies of dioxygen in non-aqueous electrolytes, as well the use of SHINERS to understand model electrode interfaces within Li-ion battery electrolytes.

References:

1. P.G. Bruce, S. Freunberger, L.J. Hardwick, J.-M. Tarascon, Nature Mater. (2012) 11 19

2. Z. Peng, S.A. Freunberger, Y. Chen, P.G. Bruce, Science, (2012) 337 563

3. Li et al. Nature (2010) 464 392
Discharge Reaction Mechanism of FeS2 Cathodes in Na Batteries: First-Principles Calculations
Authors: Momida Hiroyoshi , Oguchi Tamio
Published: February 2020

Several types of materials have been extensively studied to find suitable electrode materials for Na secondary batteries, and recently pyrite-FeS2 has attracted much interest as a cathode material of Na batteries [1]. However charge and discharge reactions in the Na/FeS2 batteries, which are governed by conversion mechanisms, are not fully understood yet especially concerning intermediate states involved in the reactions.

In this study, by using first-principles calculations for probable phases in Na/FeS2 conversion reactions, we theoretically estimate electromotive forces (EMFs) characterizing battery performances. To study atomic structure changes during the reactions, we calculate x-ray absorption spectra (XAS) of Na/FeS2 before and after Na discharges. Obtained EMF and XAS are compared with experimental results [1], and atomistic discharge reaction mechanisms in Na/FeS2 battery systems are discussed.

We use stable crystal phases as model structures of Fe-S, Na-S and Na-Fe-S systems. Calculations are based on the density functional theory within the generalized gradient approximation adopting the all-electron full-potential linearized augmented plane wave method, and XAS spectra are computed on the basis of Fermi’s golden rule with the one-electron ground states [2]. All the computations are done using the HiLAPW code.

We first calculate EMFs assuming stable Na-S crystals as a final product of discharge reactions of Na/pyrite-FeS2. Calculated results show that the most likely final product is Na2S+Fe generating EFM of about 1.2V vs. Na, consistent with the experimental results. We further investigate multi-step reactions considering Fe-S, Na-S and Na
x
FeS2 (x = 1 and 2) models as intermediate products. All assumed multi-step reactions are energetically higher, indicating that the assumed intermediates can be minor products relative to the two-phase form as FeS2-Na2S. Among the assumed multi-step reactions, we find energetically acceptable two-step reactions that produce FeS and Na
x
FeS2 intermediate phases, and the two-step reactions can give EFMs close to the two-phase average 1.2V vs. Na. Thus FeS as well as Na
x
FeS2 may be plausible intermediate products. Comparison of the calculated XAS spectra at the S K-edge with the experimental ones [1] also shows that the intermediates of FeS+Na2S likely exist during the reactions.

[1] A. Kitajou, J. Yamaguchi, S. Hara and S. Okada, J. Power Sources 247, 391 (2014).

[2] T. Oguchi and H. Momida, J. Phys. Soc. Jpn. 82, 065004 (2013).
Application of Small Angle Neutron Scattering for In Situ Measurements of Li-Ion Batteries
Authors: Seidlmayer Stefan , Zinth Veronika , Gilles Ralph , Hattendorff Johannes
Published: February 2020

Small-angle scattering is a commonly used to gain informations about the nanostructure of the investigated materials (i.e. size, volume and shape of particles). Also, neutrons are a powerful tool for in-situ investigations because of their high material penetration depths. Therefore SANS is well suited for studying any changes of these parameters inside closed battery cells under operation. Up to now only a few publications exist dealing with the SANS method for batteries and battery materials. This is mainly caused by the fact that only new developed batteries provide a reasonable thickness for transmission measurements necessary for the applied method.

In 2012 Bridges et al. used a Li||Graphite coin cell for an in-situ SANS experiment, observing the growth of the anodic SEI-layer [1], while for example Nagao et al. used the method to investigate the Li-intercalation mechanism in carbon host materials [2].

However, one major drawback in these experiments is that only cells with Li-metal as counter electrode were used.

In our approach we assemble experimental cells consisting of the same anode and cathode materials as used in commercial cells and perform in-situ SANS experiment during charging/discharging. The cells are assembled as pouch bag or coffee bag cells.

We report on our measurements with the SANS-1 instrument at Heinz Maier-Leibnitz Zentrum (MLZ), Garching. In-situ small-angle neutron scattering data of NMC||Separator||Graphite cells was collected during a complete charging and discharging cycle. In addition single battery components were measured separately to distinguish the various component signals. The in-situ data shows a variation of the integrated total scattering intensity in dependence of the state of charge. The quite noticeable step in the curve can be associated with the volume changes of the cathode or anode materials caused by the Li-intercalation process. Combining the different data sets a feasible interpretation of the charging/discharging process will be presented.

Our future aim is to further develop the in-situ small-angle neutron scattering technique to be able to monitor aging and electrode deterioration processes without the need to open the cells.

[1] Bridges, C. A., X.-G. Sun, J. Zhao, M. P. Paranthaman and S. Dai. "In Situ Observation of Solid Electrolyte Interphase Formation in Ordered Mesoporous Hard Carbon by Small-Angle Neutron Scattering." The Journal of Physical Chemistry C, 2012, 116(14), 7701-7711.

[2] Nagao, M., C. Pitteloud, T. Kamiyama, T. Otomo, K. Itoh, T. Fukunaga, K. Tatsumi and R. Kanno. "Structure Characterization and Lithiation Mechanism of Nongraphitized Carbon for Lithium Secondary Batteries." Journal of The Electrochemical Society, 2006, 153(5), A914-A919.
Local in-Operando Temperature Measurements Across the Interfaces of a Lithium Ion Battery Cell Using Microscopic Thermography
Authors: Schneider Michael , Heubner Christian , Junker Nils , Lämmel Christoph , Michaelis Alexander
Published: February 2020

The predicted widening of applications for lithium ion batteries is still lagging behind due to several disadvantages mostly concerning safety and reliability hazards caused by the heat evolution during rapid charging and discharging. For targeted material development, design optimization and battery management a detailed and fundamental knowledge of the heat evolution mechanisms and the heat transfer on the micro and macro scale is obligatory.

Most of the investigations published in literature focus on the heat evolution in lithium ion batteries and dealing with integral measurement techniques at commercially available systems. The interpretability of the measurements is rather difficult due to the complexity of the multi composite system.

For a detailed and fundamental research on the heat evolution mechanisms in the individual battery components cathode, separator/electrolyte and anode the authors developed a special electrochemical cell for microscopic in-operando thermography. Using a thermography system with high spatial and temperature resolution we were able to measure the spatially resolved temperature evolution across the interfaces of anode/separator/cathode.

Differences in the heat evolution rates of cathode, separator and anode depending on the electrochemical reactions, the state of charge and the applied electric current density are identified by the experiments. The heat evolution was investigated depending on the charging-discharging rate. The main heat evolution mechanisms are:

· the superiority of reversible heat effects due to the electrode reactions for near equilibrium conditions

· the dominating effect of Joule heating for high charging-discharging rates.

In the investigated battery setup the LiCoO2 cathode can be identified as the most decisive component for the overall heat evolution in the cell according to the ohmic resistance and remarkable high reversible heat effects.
Li7La3Zr2O12-Based Solid Electrolytes for Li Batteries with Voltages Beyond 5 Volts
Authors: Uhlenbruck Sven , Tsai Chih Long , Finsterbusch Martin , Hammer Eva , Bitzer Martin , Van Gestel Tim , Buchkremer Hans Peter
Published: February 2020

Today’s commercial electrolytes used in lithium ion batteries, e.g. aprotic solvents with Li salts and possibly gel or polymeric stabilization, do not have sufficient electrochemical stability for high voltage cells around and above 5 V. Some sulfide, oxide and phosphate solid state materials exhibit remarkable Li ion conductivity (which can be further increased by increasing operating temperature), thus enabling them as promising candidates for solid-state Li electrolytes [1]. From the oxide class of materials, garnet-like materials based on Li7La3Zr2O12 were chosen for this publication due to their reasonable lithium ion conductivity (high 10-4 Scm-1 range at room temperature), and their stability against air and also humidity so that they can be processed in ambient conditions.

Li7La3Zr2O12 where Li or Zr sites are partially substituted by Aluminum, Tantalum or Yttrium, with simultaneously optimized Li content and high total Li ion conductivity were prepared and characterized with regard to crystal structure. One focal point was put on the phase formation and especially on the ratio of the cubic to tetragonal phase. The material was subsequently processed to electrolyte foils with lateral dimensions of up to 7cm×7cm and analyzed with respect to conductivity and electrochemical properties including operation as an all solid state cell using high voltage cathode materials.

References

[1] N. Kamaya et al. Nature Mat. 10 (2011) 682-686, doi: 10.1038/NMAT 3066
Early Identification of the Li15Si4 Phase Using in-Situ Synchrotron XRD
Authors: Beattie Shane D , Weaving Julia S. , Thapar Vijay , Conner Leigh D , Aniol Maria , Nagai Aisaku , Evans Stuart , McKiernan Mary
Published: February 2020

In-situ synchrotron X-ray powder diffraction (SXRD) was performed on a Li-Si pouch cell on the high-energy beamline (I12) at Diamond Light Source. The high photon energies provided by the synchrotron allowed the beam to pass directly through the Li-Si pouch cell while still providing high resolution SXRD data. Furthermore, the large flux of the synchrotron beam allows high temporal resolution SXRD data to be collected. Fast acquisition time and high resolution SXRD patterns allows for accurate identification of the onset of Li15Si4 formation.

Obrovac and Christensen [1] showed that the fully lithiated phase for silicon at room temperature is Li15Si4. They also showed that the Li15Si4 phase is formed below 50 mV (vs. Li), which typically occurs at the end of silicon lithiation. Li and Dahn [2] used in-situ XRD to show that the Li15Si4 phase does not occur until high capacity (> 3500 mAh/g) and low voltage (< 50 mV).

The results discussed above clearly show that formation of the Li15Si4 phase can be capacity dependent. One could also theorize that the formation of Li15Si4 is voltage dependent. To further elucidate the effect of voltage on the formation of the Li15Si4 phase in-situ SXRD was performed on Li-Si cells at voltages below 50 mV.

In-situ SXRD data is shown in Figure 1 as a function of intensity (left ordinate) and as a ‘waterfall plot’ vs. time (right ordinate).

Figure 1 clearly shows that the silicon peak recedes as a function of time (and capacity), while the Li15Si4peak grows.

To better quantify the formation of the Li15Si4 phase Figure 2 shows the evolution of the volume fraction of Li15Si4 as a function of time (lower plot abscissa) and capacity (upper plot ordinate).

Figure 2 shows that the Li15Si4 phase can be observed almost immediately. As capacity increases the volume fraction of Li15Si4 continues to increase. These results show that the Li15Si4phase can be formed very early if the voltage at the silicon electrode is below 50 mV.

References:

[1] M. N. Obrovac and Leif Christensen, Electrochemical and Solid-State Letters, 7 (5) A93-A96, 2004

[2] J. Li and J. R. Dahn, Journal of The Electrochemical Society, 154 (3), A156-A161, 2007
Development of Thin Glass-Ceramic Electrolytes Via a Sol-Gel Route
Authors: Lorrmann Henning , Hartmann Sarah , Röder Manuel , Frech Florian , Kapuschinski Martina , Sextl Gerhard
Published: February 2020

Due to their high energy densitites lithium-air and lithium-sulfur are the most promising battery technologies. Both systems inhibit substantial drawbacks, though. The dendrite formation on the lithium anode and subsequent shorting of the cell is still unsolved since the first market introduction of rechargeable lithium-batteries in the early 1990s. With common liquid electrolytes dendrite formation cannot reliably be prevented. However, solid electrolytes with a high shear modulus effectively inhibit this effect.[1]

Solid NASICON-type electrolytes (e. g. Li1+xAlxTi2-x (PO4)3, LATP) offer a high ionic conductivity at room temperature and a high anodic stability. The low stability against metallic lithium, due to the reduction of the transition metal (e. g. Ti4+), requires an intermediary layer.[2] Additionally, a reliable concept for the integration of a free standing and thick (> 50 µm) “electrolyte-sheet” has yet to be proven.

In our work, dense electrolyte layers with a thickness below 1 µm were prepared by sol-gel methods (Figure 1). It was intended that a wet chemical deposition of cathode material onto the sintered electrolyte should reduce the interface resistance and that the resistance could be further optimized by varying the deposition and sintering conditions. The electrolyte/electrode interface was analyzed by means of SEM and depth-profiling XPS. Temperature dependent XRD allows for the analysis of the sintering process in situ. The interface resistance was tested galvanostatically and by electrochemical impedance spectroscopy. Electrochemical tests on the electrolyte were performed with sputtered platinum electrodes. The (spectro) electrochemical characterization (Figure 2) of thin-film electrodes on TCO coated glass substrates was realized in specially designed test cells.

This poster presents the first results on the sol-gel deposited glass ceramics as electrolyte, thin film cathodes and the interface between both components. Future work will focus on the anode/electrolyte interface (Lithium/polymer/glass-ceramic) and finally a working solid-state cell.

[1] W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J.-G. Zhang, Energy Environ. Sci.
2014.

[2] P. Knauth, Solid State Ionics
2009, 180, 911–916.
Failure Mode Analysis of Li-Ion Batteries Using In Situ Scanning Electron Microscopy
Authors: Hovington Pierre , Lagacé Marin , Marceau Hugues , Clément Daniel , Dontigny Martin , Trottier Julie , Guerfi Abdelbast , Mauger Alain , Julien Christian M , Zaghib Karim
Published: February 2020

High cycle life is a key component that any lithium-ion battery technology must achieve in order to obtain a commercial success. In this regard, multiple electrochemical (Impedance, ASI, floating current, etc.) and non-electrochemical techniques (XRD, FT-IR, SEM/TEM, etc.) are used and developed. The most complete techniques involved measurement while the battery is cycling (in situ experiment). Among them, in-situ SEM/TEM is able to focus on the same region/particle over the all range of oxidation/reduction. Hydro-Quebec has developed a complete expertise for in-situ techniques, especially in situ SEM.

Lithium Polymer Battery (LPB), an all solid battery, is the preferred battery configuration for SEM in-situ experiment. We present in Figure 1 micrographs taken during in-situ experiment of a LPB (Li/PEO based SPE/Li1.2V3O8 based cathode) showing the variation in thickness for the Li, SPE and cathode layers with the cell voltage. Only the Li thickness shows an important variation during plating and unplating. The Li plating rate can also be measured. This experiment can clearly be used to better understand the Li plating mechanism.

In figure 2 we present micrographs taken during an in-situ SEM cycling of a Li/PEO based SPE/SiO cell using backscattered electron signal. We clearly see an important decrease in the BSE intensity as a function of the cell voltage as a result of the Si phase transformation upon cycling (upon Li ‘insertion’, the BSE intensity is lower and the particle becomes darker). We also note that a region of the big particle remains white (i.e. the Li did not have sufficient time to ‘diffuse’ inside their core region). This result explains the rather low capacity observed with such particles and it gives evidence that the system is out of thermodynamic equilibrium. This in-situ experiment also shows no cracking of the relatively big SiO particles since the voltage was kept higher than 0.1V (stop at the Li22Si7 phase instead of Li22Si5) when compared to previous results [1]. We will also present in-situ SEM of nano-Si particles that did not suffer any cracking, but agglomerate (electrochemical sintering), which results in a more rigid and fractured electrodes [2]

This presentation will also used in-situ SEM to obtain a better understanding of the failure mechanism of new electrode materials, including Li-S.

References:

[1] http://batt.lbl.gov/blog/research-tasks/in-situ-sem-seeing-battery-cycling-in-action/?utm_source=rss&utm_medium=rss&utm_campaign=in-situ-sem-seeing-battery-cycling-in-action

[2] Hovington et al, (2014) ‘in situ Scanning electron microscope study and micriostructural evolution of nano silicon anode for high energy Li-ion batteries’, Journal of Power Sources 248, 457-464
Micro-Measurement and Microanalysis System for Electrode Reactions in Lithium-Ion Batteries
Authors: Liu Bernard Hao-Chih , Cheng Yu-Lun , Jiang Sheng-Xun , Fung Kuan-Zong , Tsai Shu-Yi , Ni Chung-Ta
Published: February 2020

The performance of Li ion batteries is highly dependent on the thermodynamics and kinetics of electrode reactions. If the reactions and mechanisms in or across the interfaces of electrode materials can be resolved, the better electrode design may be achieved and then the electrochemical behavior and performance of Li ion batteries may be further improved.

The electrochemical impedance spectroscopy (EIS) is a common analytical tool in the study of Li ion diffusion in the battery. EIS measures the impedance responses of the electrochemical cell under a range of AC frequencies; and the diffusion mechanisms of Li ions are investigated by the construction of the

equivalent circuit models. However, the complexity in the circuit models makes it difficult to resolve the individual interfacial reaction; recent development of micro-electrodes help to resolve some of these issues, but it fails to effectively measure reactions between materials and interfaces due to the restrictions in the conventional experimental setting. Thus, the objective of this work is to investigate the electrochemical reaction on a thin film of oxide electrodes such as LiCoO2 and/or Li4Ti5O12for lithium ion battery applications. The measurements and analysis will be conducted based on the scanning impedance microscopy (SIM) techniques, and the self-developed multi-electrode AFM probes.

A novel approach will be used to integrate AFM probe into the assembly of an advanced solid-state thin film lithium ion battery, to establish a micro/nano-scale battery measurement and analysis system.
Advanced 3D Imaging and Analysis of Lithium-Ion Battery Electrodes
Authors: Biton Moshiel , Tariq Farid , Yufit Vladimir , Shearing Paul R , Kishimoto Masashi , Gelb Jeff , Golodnitsky Diana , Peled Emanuel , Brandon Nigel P.
Published: February 2020

Meeting increasing energy demands, storage requirements and energy portability will be expedited through an ability to directly image lithium battery material nano/micro structures at high resolutions in 3D. The performance of the battery is dependent on nano/micro-structure as important reactions often occur at porous electrode interfaces. Furthermore, during processing or operation microstructural evolution may degrade electrochemical performance.

Despite their importance, battery electrode microstructures remain poorly understood, limiting current understanding of their failure. Tomographic techniques allow for the direct 3-D imaging and chracterisation of complex microstructures from millimetres down towards nanometers.

Here we present results from 3D x-ray and FIBSEM tomography of battery materials (e.g. Figure 1) down to resolutions of tens of nanometers. Quantitative analysis of critical parameters important for battery materials is evaluated, and these are linked to simulation tools to relate structure to performance characteristics. Both x-ray and FIBSEM tomography can provide this information, facilitating analysis of micro/nano structure, morphology and provide exciting opportunities to study fabrication effects or operating conditions that could cause electrode degradation and failure.

We find this approach is effective in understanding how lithium ion batteries function at high resolutions and consequently that tomography coupled with modeling/experiments can provide new insights into degradation mechanism.

Figure 1 – 3D lithium ion anode structure with MCMB particles
Electrical and Optical Properties of Lithium Phosphorous Oxynitride (LiPON) Electrolyte Thin Films with High Nitrogen Content Prepared By RF Sputtering
Authors: Su Yu Rong , Falgenhauer Jane Christine , Lupo Christian , Meyer Bruno K. , Schlettwein Derck , Polity Angelika , Janek Jürgen
Published: February 2020

Lithium phosphorus oxynitride (LiPON) is one of the promising electrolyte material for the thin-film batteries due to its superior electrochemical stability, moderate ionic conductivity and low electronic conductivity. In addition, LiPON has a wide optical bandgap (>3 eV) which makes it transparent for UV-Vis light and suitable for using in electrochromic thin film devices.

The typical value of ionic conductivity of LiPON is in the range of 0.2 to 3.3×10-6 S/cm[1]. Here we report the deposition of amorphous LiPON thin films by RF sputtering from a commercial Li3PO4 target in nigtrogen atmosphere with the ionic conductivities at room temperature as high as 6.5×10-6 S/cm with an activation energy of 0.55 eV. The average growth rate is 14 nm per minute. The electronic conductivity is found to be 2.2×10-12 S/cm. The film composition is determined to be Li3.13PO1.69N1.39by inductively coupled plasma-optical emission spectrometry (ICP-OES) and Rutherford backscattering spectrometry (RBS), which demonstrates our LiPON sample contains relatively high nitrogen content and low oxygen content. The local structure is probed by XPS and Raman spectrometry. The incorporation of nitrogen in the matrix is confirmed by both methods and the nitrogen is present in two different chemical environments corresponding to  and P-N=P.

The optical properties of LiPON are studied by variable-angle spectroscopic ellipsometry (SE) and transmission measurements. The LiPON film is found to have a bandgap of 3 eV and is highly transparent for UV-VIS light. The optical constants include refractive index n, extinction coefficient k and absorption coefficient α in the energy range of 0.58~5.5 eV are derived. The Urbach tail is also observed in LiPON thin films when photon energy is lower than the bandgap. For its application in electrochromic device, the WO3/LiPON half-cells are prepared and the electrochromic properties will be discussed.

[1] J.F. Ribeiro, R. Sousa, J.P. Carmo, L.M. Gonçalves, M.F. Silva, M.M. Silva, J.H. Correia, Thin Solid Films 522 (2012) 85-89.
Dual-Oxide Nanostructures Electrodes for High Energy Density Asymmetric Supercapacitors
Authors: D H Nagaraju , Beaujuge Pierre , Alshareef Husam
Published: February 2020

Electricity storage is necessary to address the intermittency problem from renewable energy resources such as wind and solar energy. Supercapacitors are energy storage devices which are complimentary batteries in terms of power density are attractive for many applications. Developing high energy density supercapacitor with high power density remains a challenge. Here, we present a strategy to fabricate the high energy density dual-oxide and reduced graphene oxide composites of dual-oxide asymmetric pseudocapacitors operating in an environment friendly aqueous neutral electrolyte. The 1D and 2D rGO/V2O5 nanostructures display superior electrochemical performance compared to the V2O5 nanostructure electrodes in aqueous electrolytes. Nanostructured MoO3 was used as an anode to fabricate the dual-oxide asymmetric supercapacitor. The asymmetric supercapacitor devices show a working voltage window of 1.6 V. The energy and power density values are, to our knowledge, higher than any that have been previously reported for asymmetric supercapacitors using V2O5 electrodes. 

Reference:

D. H. Nagaraju, Qingxiao Wang, P. Beaujuge and H. N. Alshareef
J. Mater. Chem. A
, 2014, 2, 17146-17152.
Broad Temperature Range Electrolytes Based on Ionic Liquid / Solvent Systems for Electrochemical Double Layer Capacitors
Authors: Dagousset Laure , Galindo Christophe , Pognon Grégory , Nguyen Giao T.M. , Vidal Frédéric , Aubert Pierre-Henri
Published: February 2020

Thermal, physicochemical and electrochemical properties of three different commercial ionic liquids N-Propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (Pyr13FSI) , 1-Butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) and 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) were investigated and compared with those of binary mixtures of these ionic liquids with gamma-butyrolactone over [223K; 373K].

It was found that the ionic conductivity of binary mixtures depends on their composition, and the highest values were obtained for a proportion close to 50%wt in ionic liquid. The addition of organic solvent enhances the conductivity and fluidity of mixtures, especially at low temperature. The ionic conductivity of mixtures reaches 1.9 mS/cm at 223K with a viscosity as low as 70cP.

The ionicity of all six electrolytes was assessed by the Walden plot approach with temperatures rising from 283K to 353K. Thus it was demonstrated that pure ionic liquids and ionic liquids/gamma-butyrolactone mixtures behaviour follows the partial Walden’s rule with α~0.8 and 0.65 respectively.

Thermal and electrochemical behaviours of ionic liquids based electrolytes were studied in mesoporous media composed of single wall carbon nanotubes SWCNT bucky papers. DSC measurement revealed that the addition of gamma-butyrolactone prevents the crystallisation of ionic liquids within the range [183K; 313K] whether the mixtures are inside a mesoporous media or not.

Additionally, electrochemical stability window has been assessed for ionic liquids based electrolytes at 223K, 293K and 373K, on glassy carbon and SWCNT mesoporous bucky paper electrodes. The association of pore size-controlled electrode materials and advanced ionic liquids based electrolytes exhibit promising performances and are under further investigation for applications in electrochemical energy storage devices in severe environment.
Polyoxometalates for Non-Aqueous Redox Flow Battery Applications
Authors: Chen Jee-Jay James , Barteau Mark
Published: February 2020

Scalable energy storage technologies are needed to enable integration of high levels of integration of intermittent energy sources such as wind and solar into the grid. Redox Flow Batteries (RFBs) designed to store energy in chemical form in the electrolyte can help to address the energy storage problem. However, most traditional RFBs are aqueous systems for which the cell voltage is limited by water splitting. Non-aqueous RFBs could permit higher cell voltages by removing this limitation. Polyoxometalates (POMs), with versatile, tunable properties, undergo multi-electron redox reactions which may meet the requirements of high performance Redox Flow Batteries.

Research conducted to date has focused on the electrochemical characteristics of different combinations of Keggin-type polyoxometalates (XMmO40
n-). Metals substituted into the Keggin framework play a key role in altering the redox properties of polyoxometalates. Based on the result, the effects of 1A or 2A counter  cations on cell potentials were fairly minor. And Keggin ions containing different central heteroatoms (phosphorous, arsenic and silicon) were compared. While the charge on the Keggin ion does affect the telative positions of redox couples in the CV spectrum, the number of redox couples is not affected.  Last mixed addenda POMs were also compared. The mechanism of addenda element effects on POM redox properties is still unclear, but the mixed addenda elements play an important role in determining the redox properties. Investigation of the mix addenda POMs is the focus of current efforts.

This research aims to select suitable polyoxometalate species that can be used for non-aqueous Redox Flow Batteries. Preliminary results have shown high coulombic efficiency (~90%), reflecting the reversibility of polyoxometalate redox reactions.
Prototype of Nanoelectrofuel Flow Batteries: Engineering Challenges and Prospectives
Authors: Katsoudas John P. , Timofeeva Elena V. , Singh Dileep , Ramani Vijay K , Segre Carlo U
Published: February 2020

New approaches to battery chemistries, cell designs, and manufacturing offer fertile ground for scientific exploration across many disciplines, and promises to revolutionize the practice of energy storage. We present a novel rechargeable nanoelectrofuel (NEF) flow battery technology which incorporates high energy density cathode and anode nanomaterials at high material loadings in a flowable and pumpable format that can be used in combination with uniquely designed flow batteries.  The NEF approach is a chemistry agnostic change in energy storage format that leverages the properties of conventional solid state batteries, flow batteries and nanofluid technology.

A unique flow battery cell design has been developed to accommodate the effective charge and discharge of nanoparticles in suspension. The combination of nanoelectrofuels and unique flow battery cells increase the system level energy density of flow batteries to and above that of solid-state lithium-ion batteries creating an attractive energy storage medium for any industry or application that relies on stable energy storage for its operations. More than 50% improvement in energy density of solid batteries with the same chemistry are possible because of a lower fraction of inactive packaging material that is used in a NEF flow battery.

We are building 40V NEF flow battery prototype, which is scalable for electric vehicle needs. This presentation will focus on engineering challenges in the development of NEF electrochemical flow reactor and the approaches that we are using to solve them. Results of computational fluid dynamics (CFD) and electrochemical modelling will be presented and compared to empirical estimations.  The utilization of these results in the context of an end product development will be discussed.

The stability and low cost of this cutting-edge innovation make it a good choice for numerous interchangeable industrial design applications, particularly the following:

Transportation (rechargeable liquid form of batteries for electrical and hybrid electrical vehicles, fast refueling, zero emissions)

Stationary power storage (battery systems for large-scale load-leveling and local house back-up systems), including

-       Renewables (efficient storage and distribution of energy from intermittent wind and solar plants)

-       Military devices (concentrated energy, fast response, easy maintenance)

This presentation will also discuss technology transfer and commercialization challenges, potential development routes for NEF flow battery, including manufacturing and product development in the context of the present players, market size, and the long term vision for the technology.
Study of Electrochemical Cells with Intermediate Gate Electrodes
Authors: Patel Akshat , Grebel Haim
Published: February 2020

Our goal is to reconstruct batteries and super-capacitors in a fundamental manner.  Thus, we introduced a third electrode, called the gate electrode, between the cathode and the anode of a battery.  In the simulations, we used a simple wet-cell battery with Zn electrode as the anode and Pt electrode as the cathode.  In the experiments we used 5% acetic acid as an electrolyte.  The gate electrode was constructed as a permeable capacitor: two thin Au/Pd films were deposited on each side of a 10-micron Teflon filter.  Thus, the gate electrode was conductive and permeable to the passing ions.  Simulations indicated that by regulating the voltage on the capacitive-like gate electrode, we were able to control the electrolyte potential near it.  Thereby, the flow of ions through this membrane was also regulated. Subsequently, the electronic current in the external circuit, was linearly controlled. 

In principle, the gate electrode could be constructed in several ways.  Here, we considered capacitor-like gate electrodes.  One plate of the capacitor was grounded and an external potential bias was applied to the other plate.  Simulations (see figure) indicated that when the bias potential increased, the cell's current substantially decreased.  In the experiments, we grounded the cathode to prevent the biasing potential from floating.  A reference electrode was attached to the un-grounded plate and we ascertained that the potential on the capacitor with respect to the reference electrode depended linearly on the bias.  Experiments validated the simulations: we demonstrated that by applying a voltage bias to the capacitor-like gate electrode, we could linearly controlled the external circuit current, Icell.  This is the first step towards controlling the current produced by a battery and in essence, the first step towards constructing self-powered ion transistors.

Figure 1
Effect of Additives Reducing Solubility of ZnO on the Decomposition Kinetics of a Supersaturated Zincate Solution
Authors: Chladil Ladislav , Vanýsek Petr , Máca Josef , Cech Ondrej
Published: February 2020

Anodic polarization of zinc electrode during discharging of alkaline Ni-Zn accumulators is accompanied by dissolution of the oxidation product into the alkaline electrolyte. The maximum amount of dissolved zinc species could be much higher than the equilibrium state, which is known as the state of saturation. Supersaturated electrolyte (SZS – supersaturated zincate solution) could subsequently decompose to a solid ZnO precipitate. The decomposition process consists of initial formation of ZnO nucleation centers followed by increased precipitation. It is clear that if the rate of decomposition is high, the ZnO will precipitate not only on the surface of the negative electrode, but in the whole volume of the cell. Rate of the decomposition process is influenced by temperature, initial supersaturation concentration of zincate, concentration of hydroxide (pH) and also by presence of specific additives. In relation to the last mentioned, for example the study of SiO3
2- additive effect on decomposition kinetics shows that SiO3
2- causes complete inhibition of decomposition by its adsorption on the surface of ZnO.

Actual research in the field of Ni-Zn batteries deals with electrolytes with reduced ZnO solubility, which limit the amount of zinc transferred from electrode to electrolyte and back during cycling and thus reduce the electrode shape changes. These electrolytes are based on the alternative anion groups such as F-, CO3
2-, or PO4
3-. In many cases the battery development also considers the organic additives into the base electrolyte, which serve as Zn dendrite inhibitors. These additives are mostly surfactants, which means that they have also the ability to adsorb on the surface of any particles.

With respect to above-mentioned fact we focused our attention on the measurement of decomposition kinetic rate of SZS with regard to different additives, which are mostly used in the Ni-Zn batteries. Precipitation of ZnO is accompanied by the release of hydroxyl ions that linearly increase electrolyte conductivity as the decomposition process is ongoing. For this reason we determine the decomposition rate by conductometric measurements using a four electrode platinum-glass conductivity cell Knick Messcell 227. Conversion characteristic between the conductivity and concentration of dissolved zinc over the saturation state were determined by complexometric titration for the each type of measured electrolyte.

We trust, that our result, which describes the decomposition kinetic in low solubility electrolyte, can contribute to the better understanding of the complex phenomena of Ni-Zn battery.
Performance Enhancement of Pd/C for Direct Formic Acid Fuel Cell By Heat Treatment of the Carbon Black
Authors: Tsujiguchi Takuya , Tsuchiya Yuki , Onishi Ryo , Osaka Yugo , Kodama Akio
Published: February 2020

Direct formic acid fuel cell, DFAFC, has been attracted much attention due to its high power density when Pd-based catalyst has been used for the anode. In this study, we investigated the effect of the heat treatment for the carbon support in Pd/C. Vulcan carbon (Cv) and Ketjen black (CK) were used selected as a carbon support. The three types of heat treatments were conducted in each support; calcination at 1273 K for 1h in nitrogen atmosphere, steam activation at 1122 K for 1h in nitrogen atmosphere and both treatments in the order of calcination and steam activation. Non-heattreated carbon blacks were also prepared, and the formic acid oxidation activities of four catalysts were measured and compared. In the case of Vulcan carbon, it was found that Pd/CV treated by only calcination showed the higher catalytic activity in four catalysts. On the other hand, in case of Ketjen black, non-treated one showed highest catalytic activity comparing to the treated catalyst. In the presentation, we will show the results of the characterization of the catalysts, and then, discuss why high catalytic activity could be obtained.
Â Design of Î±-CoMoO4 Nanoflakes on Carbon Cloth and Investigation of Their Pseudocapacitance in Non-Aqueous Electrolyte and Electro-Oxidation of Methanol
Authors: Narayanasamy Padmanathan , Shao Han , Selladurai S. , O'Dwyer Colm , Razeeb Kafil M
Published: February 2020

Nanocrystalline cobalt molybdate (CoMoO4) nanoflakes were grown directly on carbon fiber cloth (CFC) via a simple hydrothermal method without any template or surfactant. Structure and morphology of the sample was characterized by x-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM), and transmission electron microscope (TEM). A symmetric supercapacitor was fabricated using nanocrystalline CoMoO4 nanoflakes as both negative and positive electrodes. The device has delivered a maximum specific capacitance of 8.3 F/g at a constant current density of 1 A/g in organic electrolyte. It offers a reasonable energy (2.6 Wh/kg) and power (748.8 W/kg) density as comparable to the carbon based symmetric supercapacitors. As a catalyst for methanol oxidation, the CoMoO4 nanoflakes showed high current density (25 mA/cm2) and low onset potential (0.38 V). The impressive bi-functional electrochemical activity of CoMoO4 on CFC mainly attributed to their porous microstructure, reasonable electrical conductivity resulted from binder-free and intimate metal oxide/substrate integration.
Novel Carboxylated Poly (glycidyl methacrylate) Grafted Cellophane for Proton Exchange Membrane Fuel Cell Applications
Authors: Abu-Saied Mohamed
Published: February 2020

Carboxylated poly (glycidyl methacrylate) grafted cellophane for Proton Exchange Membrane Fuel Cell have been prepared through two steps. The first step was introducing of epoxy groups to its chemical structure through grafting process with PGMA. The second step was converting the introduced epoxy groups to carboxylic group through a reaction with iminodiacetic acid. Grafting and carboxylation processes were verified. Essential characters required for polyelectrolyte fuel cell membrane especially ionic conductivity, methanol permeability, IEC, thermal stability and high mechanical properties were investigated. The thickness of grafted membranes was increased with grafting degree. The IEC increase when the grafted membrane reacted with iminodiacetic acid. The methanol permeability of Carboxylated PGMA grafted cellophane which consider as essential character for PEM fuel cell application was found lower than of Nafion. The obtained results are very promising and opening new area for conducting further investigations considering the very low price of cellophane compared to Nafion.
Wearable and Washable Supercapacitor Based on Adhering Architecture
Authors: Yoo Young Geun , Park Soomin , Nam Inho , Bae Seongjun , Park Jongseok , Yi Jongheop
Published: February 2020

Wearable electrical devices have attracted tremendous attention along with the improvements of electronic technologies. One of the most important prerequisites of such electric systems is an energy storage system with durability against various stresses in daily life (e.g. mechanical impacts or invasion of humidity). In this research, we report on a development of all-solid-state, foldable and washable supercapacitor system. A constructed carbon network was readily assembled into a full-cell by its self-adhering architecture. The as-prepared system operated stably even under the conditions of severe folding and washing without capacity fading, which is attributed to both robust electrical connectivity of the fibrous carbon network and intimate contact between solid electrolyte/electrodes. In addition, a simple modification of electrode greatly enhances the energy density of system. The collected results suggest that this supercapacitor system can be a promising candidate for practically available and wearable energy storage systems with high cost-effectiveness and scalability.
Co3O4 Nanosheets Deposited By the Sacrificial Anode Method and Their Pseudocapacitive Behavior
Authors: Chou Li-Yao , Kung Chung-Wei , Ho Kuo-Chuan
Published: February 2020

Spinel cobalt oxide (Co3O4), an attractive material possessing great electrochemical properties, has been prepared by various methods such as solvothermal method, chemical bath deposition, electrodeposition, thermolysis and plasma-assisted deposition. However, these methods require either complicated process, high temperature treatment or external power supply to prepare Co3O4. To overcome these problems, the sacrificial anode method, which belongs to an electrochemical deposition, is proposed in this study to prepare cobalt hydroxide thin film on a carbon cloth substrate. The obtained thin film is completely converted to Co3O4 by a low-temperature ozone treatment. In this facile, self-powered process, an aluminum foil, serving as the sacrificial anode, was immersed into an electrolyte containing Co ions and the donated electrons would flow along the external circuit to the cathode substrate, i.e., the carbon cloth; the deposition of cobalt hydroxide started spontaneously due to the potential difference (as shown in scheme 1). Firstly, a nanosheets structure was observed on the carbon cloth substrate by scanning electron microscope, and the composition of this film was confirmed to be α-Co(OH)2 and Co3O4 before and after the ozone treatment, respectively. By comparing the standard potentials of the possible reactions as well as recording the pH value of the electrolyte and other experimental observations during the deposition, the reaction on the cathode was confirmed to be: NO3
- + 7H2O + 8e− ⇔ NH4
+ + 10OH-. By appling X-ray photoelectron spectroscopy, the atomic ratio of N to Co element in the obtained thin film can be calculated, and the chemical formula of the obtained α-Co(OH)2 film can be further confirmed to be Co(OH)1.85(NO3)0.15. After confirming the reaction occurred on the cathode and the chemical formula of the obtained thin film, the expected mass loading of the film can be calculated from the accumulated charge consumed during the deposition. Moreover, an accurate mass calibration curve was constructed by using the UV-Vis absorption data to precisely estimate the actual mass loading of the film. Comparing the actual and ideal mass loading, the Faraday efficiency of the deposition was finally calculated to be 94% when the accumulated charge for the deposition is 2.0 C. In this process, the rate of the deposition can be easily controlled by tuning the concentration of the electrolyte and the surface area ratio of the anode to cathode. The effects of these two factors on the rate of the deposition and the capacitive performance of the obtained films were also investigated. Finally, a high specific capacitance of 346 F/g was achieved. The proposed method offers advantageous in terms of large-area deposition and scale-up possibility for obtaining Co3O4 thin films.

Figure 1