bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resolving the Discrepancy in Tortuosity Determination for Battery Porous Electrodes Via a Numerical Approach
Authors: Nguyen Tuan-Tu , Demortiere Arnaud , Fleutot Benoit , Delobel Bruno , Cooper Samuel J. , Delacourt Charles 
Published: May 2020

The tortuosity factor of porous electrode microstructure is a crucial input parameter for numerical models of batteries as it strongly influences the electrode performance. As such, it is very important to have a method to determine this parameter accurately, based on a definition that reflects the design of the cell.
Various experimental methods have been developed for either directly measuring or indirectly inferring the tortuosity factor; however, numerical approaches, based on 3D image data, are now gaining interest in the battery community, due to the advances in nanoscale tomographic imaging methods. The standard definition of the tortuosity factor solves the Fick diffusion equation at steady-state, i.e., between two parallel constant-value boundaries. Although this approach has been widely used for porous materials, including both electronic insulators (e.g., a battery separator), and electronic conductors (e.g., battery porous electrodes), it may be the case that the definition needs to be adjusted depending on the scenario being observed.
In this study, we intend to give an insight into the appropriate way to determine the tortuosity factor of battery porous electrodes and the impact of various tortuosity determination methods is investigated. An additional module that relies on the symmetric cell method [1] [2] was implemented in the TauFactor software package [3] to compare with the already-implemented diffusion-based method [4]. This symmetric cell method refers to the measurement of the ionic current distribution inside the pores using AC impedance based on a symmetric cell setup. Figure 1 shows the workflow for tortuosity determination applied in this study. The integration of this module in TauFactor might be interesting for tortuosity determination at the microscale since it is the same method as at macroscopic scale observed in various experimental approaches.

Figure
1
. Illustration of the workflow for tortuosity determination applied in this work. The module recently implemented in TauFactor allows calculation based directly on tomographic data in symmetric cell configuration, and generates a simulated impedance spectrum. A macroscopic model such as TLM or Newman’s model is used to extract the tortuosity value of the electrode.

References:

[1] Landesfeind, J. et al.; J. Electrochem. Soc.
2016, 163 (7), A1373–A1387
[2] Malifarge, S. et al.; J. Electrochem. Soc.
2017, 164 (11), E3329–E3334
[3] Cooper, S. J. et al.; SoftwareX
2016, 5, 203–210
[4] Cooper, S. J. et al.; Electrochimica Acta 251 (2017) 681–689
[5] Pouraghajan, F. et al.; J. Electrochem. Soc.
2018, 165

Figure 1
Using Scanning Ion Conductance Microscopy to Measure Ion Conductivity and Permeability in Porous Materials
Authors: Payne Nicholas , Dawkins Jeremy , Schougaard Steen Brian , Mauzeroll Janine 
Published: May 2020

Composite electrodes can significantly improve the performance of an electrochemical device by maximizing surface area and active material loading. Typically, additives such as carbon are used to improve conductivity and a polymer is used as a binder leading to a heterogeneous surface film with thickness on the order of tens of microns.
For such composite electrodes, good ionic conduction within the film is critical to capitalize on the increased loading of active material and surface area. Ionic conductivity within a film can be tricky to measure directly and homogenization models based on porosity are often used as a proxy. Scanning Ion Conductance Microscopy (SICM) has traditionally been a topography-mapping microscopy method. We will outline a new function and demonstrate SICM’s capacity for measuring ion conductivity within lithium-ion battery composite electrodes.
Vibrational Spectroscopy in the Study of Composite and Nanostructured Materials for Electrochemistry
Authors: Korzeniewski Carol , Liang Ying , Bukola Saheed , Creager Stephen E 
Published: May 2020

Our research group has recently demonstrated the ability to probe within composite membranes formed by sandwiching single layer graphene (SLG) between two Nafion layers (Nafion 211, 25 µm thickness). These graphene-sandwich membranes have shown high selectivity for proton transport across electrochemical cells [1,2]. Using a microscope equipped with an oil-immersion objective, the graphene layer is readily detected in confocal Raman microscopy depth-profiles (z-direction profiles) of the composite membranes. Spectra are sensitive to defects and stress within the buried graphene layer. This presentation will discuss the use of confocal Raman microscopy for structural characterization and spatial profiling in the development of composite polymer electrolyte membranes that contain a graphene layer as a barrier to ion transport. In a second application area, infrared spectroscopy is being adapted to investigate properties of Nafion ionomer particles in dilute dispersions and during transformation to gel and solid phases through the use of time-resolved attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Since the properties of dispersing fluids can affect the mechanical strength of solution-cast Nafion thin films [3], it is of interest to gain insights into ionomer properties in the dispersion and during phase changes. A well-resolved peak associated with vibrational motions of the Nafion side chain -SO3
-end group is shown to be sensitive to gel-phase development. The persistence of hydration water in the vicinity of the -SO3
-group helps maintain a constant local refractive index that limits optical distortion in the band as the ionomer assembles into the phase-separated framework structure of the solid membrane. ATR FTIR measurements predict trends in evaporative water loss from the dispersion and entry into the gel-phase consistent with expectations of gravimetric measurements and earlier studies [3] of Nafion ionomer dispersion properties.
1. Bukola, S., et al. J. Am. Chem. Soc. 2018, 140, 1743.
2. Bukola, S., et al., ACS Appl. Nano Mater.
2019, 2, 964.
3. Kim, Y.S., et al., Macromolecules
2015, 48, 2161.
Structure-Performance Relationships for SOFC Electrodes
Authors: Shekhar Rustam Singh , Bertei Antonio , Monder Dayadeep S. 
Published: May 2020

The performance of solid oxide fuel cells (SOFCs) depends critically on the microstructure of the composite cermet electrodes used in these devices. This presentation will discuss how microstructure models can be used to predict the reaction site density and effective transport properties. These properties include active three phase boundary length, effective conductivities of the electronic and ionic phases, effective diffusivities, etc. which are then used in a coupled physics model to predict SOFC performance. These multiscale models will be demonstrated using two architectures for SOFC electrodes: a) conventional composite powder based electrodes using a sintered mixture of ionic conductor and electronic conductor particles, and b) infiltrated electrodes where the ionic conductor particles are sintered and then the electronic conductor phase is deposited on this scaffold using solution infiltration.
We will demonstrate the impact of changing the electrode `recipe' on cell performance, focussing on experimentally measurable and controllable parameters such as particle sizes and phase volume fractions. The figure illustrates this point by showing in the upper plot how the active three phase boundary length for infiltrated electrodes changes with varying electronic phase volume fraction and is an order of magnitude higher than that for conventional electrodes at a much lower volume fraction. Active three phase boundary length and other effective properties derived from the microstructure models when plugged into the multiphysics models simulating fuel cell performance clearly demonstrate how and why infiltrated electrodes are capable of dramatically higher performance (see lower plot). The presentation will close with recommendations for high performance SOFC electrode design keeping particle size constraints imposed by the high operating temperatures in mind.

Figure 1
(Invited) Determining Dielectric, Electronic, Magnetic, and Structural Properties of Van Der Waals Materials from First Principles
Authors: Vandenberghe William , Laturia Akash , Kramer Aaron Austin , Tiwari Sabyasachi , Van de Put Maarten 
Published: May 2020

Van der Waals materials have recently received great interest in the research community because of the ability to exfoliate and grow mono- or few-layer materials. Some important future possible applications are found in the field of nanoelectronics where extremely scaled transistors or magnetic memory devices are envisioned. However, there are more than 1,000 van der Waals materials known to date and an exhaustive experimental investigation is very expensive. This makes the accurate theoretical prediction of materials properties from first principles, enabling the identification of the most promising van der Waals materials possible, very valuable.
We show how the dielectric, electronic, magnetic, and structural properties of various van der Waals materials can be determined from first principles. We exhibit our robust methodology to extract the dielectric response of a monolayer/few-layer structure and calculate the low- and high-frequency dielectric constant of hexagonal boron-nitride and transition metal dichalcogenides (TMDs). We reveal a relatively small dependence of the dielectric constant on the number of layers. Surprisingly, we find a very large ionic contribution the dielectric response in TMDs in the tetragonal phase.[1] We also show how elemental tellurium is a promising material for extremely scaled nanowires and a possible successor for silicon. We predict that when fabricated with extremely small diameter, tellurium nanowires have a bandgap that exceeds 1 eV, while silicon’s bandgap increases excessively to above 4 eV.[2] We also show how the van der Waals bonds in tellurium naturally favor the formation of nanowires. Finally, we show how the Curie temperature can be computed in dilute doped TMDs from first principles, taking into account crystal anisotropy.
[1] A. Laturia, M. L. Van de Put, and W. G. Vandenberghe, "Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk," npj 2D Materials and Applications, vol. 2, no. 1, p. 6, 2018/03/08 2018.
[2] A. Kramer, M. L. Van de Put, C. L. Hinkle, and W. G. Vandenberghe, "Trigonal Tellurium Nanostructure Formation Energy and Band gap," in 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD), 2019, pp. 1-4: IEEE.
(Invited) Pt/Metal Oxide/Ti and Pt/Metal Oxide/Carbon Composite Films for Ethanol Oxidation
Authors: Pickup Peter G , Hang Hui 
Published: May 2020

Metal oxides such as RuO2 and SnO2 can promote the oxidation of organic fuels at Pt nanoparticles in a number of ways. These include changing the d-band level of the Pt via electron transfer (electronic effect) and providing surface –OH functionality for the oxidation of adsorbed CO (bifunctional effect) [1]. Carbon black coated with a mixture of Ru and Sn oxides has been shown to increase the activity of Pt for ethanol oxidation without a significant loss of selectivity for its complete oxidation to CO2 [2].
Here we report on the use of various mixed metal oxide composites prepared by thermal decomposition of metal acetylacetonate complexes (M(acac)n). Oxide layers were deposited onto Ti foil and high surface area carbon electrodes, and drop coated with preformed Pt nanoparticles. Cyclic voltammetry in H2SO4(aq) and polarization experiments in a proton exchange membrane cell were used to study the co-catalytic effects of the oxide layers. The use of acetylacetonate precursors provides a versatile method for screening libraries of oxide supported catalysts, as well as the production and screening of electrodes for fuel cells.
Initially, decomposition of Ru(acac)3 and Sn(acac)2 and their mixtures on Ti foil electrodes was investigated. These experiments reproduced the effects previously observed with oxide layers deposited on glassy carbon from KRuO4 and SnCl4 [3]. Deposits formed from both complexes increased the activity for ethanol oxidation of Pt nanoparticles drop coated onto their surfaces, while use of mixtures produced a strong synergistic effect. Deposits formed by thermal decomposition of a variety of other acac complexes, including Ga(acac)3, Zr(acac)4, and In(acac)3, also increased the activity of Pt nanoparticles for ethanol oxidation.
Mixed Ru+Sn oxides were also produced by thermal decomposition of Ru(acac)3 and Sn(acac)2 on carbon black, in order to better characterize the oxide deposits and produce catalysts that could be used in fuel cells. X-ray diffraction and energy dispersive X-ray spectrometry confirmed the presence of a mixed oxide. Preformed Pt nanoparticles were adsorbed onto the oxide coated carbon, supported on carbon fiber paper, and the resulting electrodes were evaluated for ethanol oxidation in a proton exchange membrane cell at 80 °C.

Acknowledgments:
This work was supported by the Natural Sciences and Engineering Research Council of Canada and Memorial University.
[1] G.M. Alvarenga, H.M. Villullas, Current Opinion in Electrochemistry, 2017, 4, 39-44
[2] D.D. James, R.B. Moghaddam, B. Chen, P.G. Pickup, Journal of the Electrochemical Society, 2018, 165, F215-F219
[3] R. B. Moghaddam and P. G. Pickup, Electrochim. Acta, 2012, 65, 210– 215
(Invited) Design and Development of Novel Electrolytes for Batteries and Supercapacitors
Authors: Wieczorek Wladyslaw 
Published: May 2020

Electrolytes are often forgotten parts of batteries and super capacitors compared to numerous review papers and textbooks describing properties of electrode materials. The intention of the present work is to fill the gap and bring electrolytes to the attention of the scientists working in the field of electrochemical energy conversion and storage devices. New challenges appearing on the nowadays battery and super caps market force researchers to design novel electrolytes often baring features not found in up to date studied systems. These challenges are aimed to be addresses and discussed. In the present work three types of electrolytes for application in modern batteries or super caps will be presented and discussed.
Strategy on design of new Huckel type anions for electrolyte salts is presented in the context given by the review of legacy and state-of-the-art systems. Synthesis, conditions for handling, stability and electrochemical parameters of salts used or with a potential for use in lithium-ion cells are described. Effect of solvent mixtures, selection strategy of salts and solvents for battery mixtures for maximization of chosen parameters or for given application is explained.
We are going to show how crystallographic studies allow for a better understanding of electrochemical properties of Huckel type salts. Comprehensive structure analysis of crystalline materials reveals valuable information about coordination ability of anions and provides the basis to develop the model of poly (ethylene oxide) electrolytes and liquid systems. Results revealing new aggregation modes at high concentrations of lithium salts involving releasing cations by self-assembly of anionic sub network will be presented.The discovering and understanding the phenomena related to the organization of such systems in the solid state is crucial for the elaboration of novel electrolytes and gives information about cation and anion coordination in electrolytes.
Also we are going to present novel hybrid polymeric electrolytes with unmodified and surface modified fillers based on silica, alumina and titania of different grain size. Special emphasize will be put on proper choice of the filler leading to preparation of composite system with enhance conductivities and lithium cation transference number compared to unmodified polymeric electrolytes.
At the end we are going to discuss properties of several proton conducting gel polymeric electrolytes with various solvent ratios, to be used as electrolytes in super capacitor applications. The influence of the gel composition on the ionic conductivity, temperature behavior and electrochemical properties has been studied in a large temperature range (-40 to 80 °C).
.
Self-Organizing Anodization in Pure Molten Ortho-Phosphoric Acid: Nanoporous Niobium Oxide Layers
Authors: Altomare Marco , Cha Gihoon , Schmuki Patrik 
Published: May 2020

The anodic oxidation of niobium[1–4] is investigated in an electrolyte composed of pure, molten ortho-phosphoric acid, i.e. o-H3PO4.[5–7] In a range of applied potential of 2.5-60 V and for temperatures of 60-110°C, porous niobium oxide layers can be formed.
Pore ordering and layer morphology depend on the anodization voltage, time and temperature.
At 100°C and 5 V, vertically-oriented, defined amorphous nanochannels grow with an average diameter of 6-8 nm. Higher voltages (10-20 V) lead to a lower pore ordering and to a less defined morphology that resembles a “fish bone” structure. Interestingly, at 40-60 V and after a sufficiently long anodization time (≥ 30 min), we observe the formation of a partially crystalline Nb2O5 hierarchical structure. Such structure shows a bimodal pore size distribution, with some 100 nm wide main pores that branch out into ~ 10 nm sized nanochannels.
We propose that high voltages (> 40 V) cause significant heating at the oxide/metal interface and a consequent partial crystallization of the anodic oxide. The main pore walls, partially crystalline and hence more stable in the anodizing environment, result from a gradual dissolution of the side nanochannels.
[1] Q. Lu, T. Hashimoto, P. Skeldon, G. E. Thompson, H. Habazaki, K. Shimizu, Electrochem. Solid-State Lett.
2005, 8, B17–B20.
[2] I. Sieber, H. Hildebrand, A. Friedrich, P. Schmuki, Electrochem. commun.
2005, 7, 97–100.
[3] J. Choi, J. H. Lim, S. C. Lee, J. H. Chang, K. J. Kim, M. A. Cho, Electrochim. Acta
2006, 51, 5502–5507.
[4] W. Wei, K. Lee, S. Shaw, P. Schmuki, Chem. Commun.
2012, 48, 4244.
[5] M. Altomare, O. Pfoch, A. Tighineanu, R. Kirchgeorg, K. Lee, E. Selli, P. Schmuki, J. Am. Chem. Soc.
2015, 137, 5646–5649.
[6] K. K. Upadhyay, M. Altomare, S. Eugénio, P. Schmuki, T. M. Silva, M. F. Montemor, Electrochim. Acta
2017, 232, 192–201.
[7] K. K. Upadhyay, G. Cha, H. Hildebrand, P. Schmuki, T. M. Silva, M. F. Montemor, M. Altomare, Electrochim. Acta
2018, 281, 725–737.
Studies on Electrochemical Performances of CZTS Anode for Lithium-Ion Batteries at Low-Temperature
Authors: Hidaru Zeru Syum , Venugopal Boya , Sabbah Amr , Reta Tadesse Billo , Wu Heng-Liang , Chen Li-Chyong , Chen Kuei-Hsien 
Published: May 2020

Lithium-ion batteries (LIBs) function as power sources in various environments and the effect of temperature is one of the major factors which limits the performance and proper operations in in cold climates or high altitude areas and in space applications. Hence, the poor charge/discharge rate and short lifetime of LIBs in low-temperature areas have restricted its application for electric vehicle (EV) or a hybrid EV. In this work, copper zinc tin sulfide (CZTS) thin-film anode materials with different mixtures of electrolytes has been prepared to study the electrochemical performance at low-temperature environments. The CZTS anode, prepared from EC/DEC/DMC electrolyte has demonstrated higher efficiency and reversible capacity at -10 oC as compared to the binary electrolyte obtained from EC/DEC electrolyte. The performance of the electrolyte at different temperature ranges and the corresponding electrochemical performance of CZTS electrode is systematically analyzed. The Kinetics and surface morphology of the as-prepared CZTS anode has been analyzed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and Scanning electron microscope (SEM) respectively.
As compared to the room temperature capacity, the CZTS has demonstrated outstanding capacity retention around 55.3 % at -10 oC in the ternary solvent electrolyte mixtures after 100 cycles at 500 mA/g current density. However, in the binary EC-DEC based electrode, a rapid capacity degradation with a capacity retention of only around 27.2 % of the room temperature capacity has been observed at the same experimental conditions. This method could be an alternative approach to study the effect of electrolyte and the performance of the anode materials in the design of thin-film micro-batteries for next-generation sub-zero temperature applications. The detail characterization and experimental results with the future perspective of this study will be discussed here.
Electrochemical Self-Assembly of CuSCN/4-Cyano-4’-(N’-Methyl)Stilbazolium Hybrid Thin Films
Authors: Suzuki Toru , Tsuda Yuki , Nakamura Tensho , Uda Kyota , Yamakado Ryohei , Okada Shuji , Yoshida Tsukasa 
Published: May 2020

Electrochemically self-assembled (ESA) CuSCN/4-(N,N-dimethylamino)-4’-(N’-methyl)stilbazolium (DAS) hybrid thin film was found to exhibit concerted photoluminescent (PL) property based on energy transfer from CuSCN to DAS [1]. The amount of co-precipitated DAS (P
DAS) during ESA linearly increased on increasing DAS concentration (C
DAS) in the bath but changes its slope due to switching of dye loading mechanism from diffusion limited to surface reaction limited [2]. The full analysis revealed the switching border to be dependent on the ratio between the concentration of CuSCN precursor complex, [Cu(SCN)]+ (C
comp), and C
DAS as C
comp/C
DAS = ca. 31 [3]. When the dye loading operates as surface reaction limited, phase separation of CuSCN and DAS in nano-scale occurs to exhibit efficient PL. Thus, finding an alternative chromophore with higher or lower affinity with CuSCN than DAS should result in shifting of the switching border with smaller or larger C
comp/C
dye than the above indicated value for DAS. In this study, we employed 4-cyano-4’-(N’-methyl)stilbazolium (CNS) for ESA with CuSCN. CNS has a strong dipole moment due to the presence of strongly electron withdrawing cyano group and thus is expected to exhibit a higher affinity to CuSCN than DAS.
CuSCN/CNS hybrid thin films were obtained by cathodic electrolysis with various C
CNS while fixing C
comp = 2.5 mM. P
CNS linearly increased upon increase of C
CNS and changes its slope at around 200 μM, far larger than the switching point observed for DAS (around 60 μM). The steep slope for the low C
CNS range should be determined by the diffusion of CNS to yield its diffusion coefficient D
CNS = 1.49×10-6 cm2 s-1, slightly larger than that found for DAS (D
DAS = 1.25×10-6 cm2 s-1). On the other hand, about 3 times larger P
CNS for given dye concentrations and steeper slope of surface reaction limited regime for CNS than those found for DAS indicate higher adsorption stability of CNS than DAS to CuSCN surface. Soaking the CuSCN/CNS hybrid thin films electrodeposited at C
CNS = 60 and 800 μM to represent the dye loading as diffusion and surface reaction limited, respetively, into dimethylacetamide resulted in partial and total extraction of CNS to reveal entrapment and phase-separation of CNS, just like the case of CuSCN/DAS. The maximum P
CNS appears to be saturated when C
CNS > 800 μM for CNS aggregate to occupy close to 30% of the total film volume.
The present results already nicely support the validity of the switching of ESA mechanism, being common for both DAS and CNS. Smaller C
comp/C
CNS for the switching border and larger stability constant for surface complex formation are expected for CNS than DAS from full analysis.
[1] K. Uda et al., ACS Omega, 4, 4056-4062 (2019).
[2] Y. Tsuda et al., Monatsh. Chem., 148, 845 (2017).
[3] Y. Tsuda et al., J. Electrochem. Soc., 166, B3096-B3102 (2019).

Figure 1