bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrolyte Effects in Manganese Oxides in Context of Water Splitting: In Situ SERS and Corrosion Studies
Authors: Ranjan Chinmoy , Pavlovic Zoran Miroslav , Gao Qiang , Schloegl Robert 
Published: February 2020

Non noble metal "earth abundant" electrocatalysts will significantly reduce the costs and make it possible to use electrochemical water splitting (electrolysis) on a very large scale. Non noble metal catalysts can be an effective replacement even if their electrochemical activities are a fraction of their noble metal counterparts. If these catalysts can be developed to an extent where their operational lifetime would become comparable to their noble metal counterparts, a large part of the problem would be solved. MnO2 is earth abundant and well known for catalyzing oxygen evolution. A form of MnOx cluster is known to catalyze water oxidation in photosynthesis.
In order to understand the limitations of this catalyst under the operational conditions, it is important to study this material in situ. Electrodeposited of MnOx on the surface of Au was studied using in situ Surface Enhanced Raman Spectroscopy (SERS) is used for tracking the structural changes of hydrous MnOx. Significant amount of potential and electrolyte dependent material dynamics were revealed in the MnOx system. Besides in-situ study of catalyst structure, ex situ analysis of corrosion using flow cells combined with atomic emission spectroscopy was carried out alongside explicit detection of oxygen. Various kinds of electrolytes were used to evaluate the effects of cations, anions and solution pH on molecular structure and performance of MnOx catalysts. Charge to radius ratio of alkali metal ions affected the reactivity of the oxides and was seen to influence reaction under both potentiostatic and potentiodynamic conditions with Li+ and (K+, Cs+) containing electrolytes showing the lowest and highest activities respectively. Strong effects on catalyst structure and performance were also seen when various anions such as perchlorate or borate were inluded in the electroytes being investigated.
References:
Qiang Gao, Chinmoy Ranjan,* Zoran Pavlovic, Raoul Blume, and Robert Schlögl. ACS Catalysis 2015, pp 7265-7275

Figure 1
A New Series of Anolyte Molecules for Non-Aqueous Redox Flow Batteries
Authors: Duan Wentao , Huang Jinhua , Brushett Fikile R. , Wang Wei , Moore Jeffery S. , Liu Jun , Wei Xiaoliang , Zhang Lu 
Published: February 2020

Nonaqueous redox flow batteries (NRFB) have emerged as a promising next-generation grid-scale energy storage solution because of their wide voltage window and hence potential higher energy densities.1-4 The development of redox active materials is essential to enable extensive deployments of such technology. Catholyte (high potential) molecules have been extensively investigated and reported,5,6 while in contrast there is still a dearth of anolyte (low potential) counterparts.
In this presentation, we report the design of a new anolyte molecule series. The materials, for both pristine and modified forms, are composed of aromatic heterocyles. These molecules exhibit low electrochemical potentials and high solubilities in organic solvents. Coupling with catholyte molecules, high cell voltages around 2.4 V could be achieved, as shown from cyclic voltammetry (CV) results of the pristine form in Fig. 1a. Flow cell performances are evaluated at a concentration of 0.5 M. As shown in Fig. 1b, excellent efficiencies are observed at a current density of 10 mA/cm2, with columbic efficiency (CE) ~ 93%, voltage efficiency (VE) ~ 77%, and energy efficiency ~ 72%. Influences of solvents and supporting electrolytes are also covered.
References:
1. W. Wang, Q. Luo, B. Li, X. Wei, L. Li, Z. G. Yang, Adv. Funct. Mater.
2013, 23, 970
2. K. Gong, Q. Fang, S. Gu, S. Li, Y. Yan, Energ. Environ. Sci.
2015, DOI: 10.1039/C5EE02341F.
3. G. L. Soloveichik, Chem. Rev.
2015, DOI: 10.1021/cr500720t.
4. X. Wei, W. Xu, J. Huang, L. Zhang, E. Walter, C. Lawrence, M. Vijayakumar, W. A. Henderson, T. Liu, L. Cosimbescu, B. Li, V. Sprenkle, W. Wang, Angew. Chem. Int. Ed.
2015, 54, 8684.
5. J. Huang, L. Cheng, R. S. Assary, P. Wang, Z. Xue, A. K. Burrell, L. A. Curtiss, L. Zhang, Adv. Energy Mater. 2015, 5, 1401782.
6. J. Huang, L. Su, J. A. Kowalski, J. L. Barton, M. Ferrandon, A. K. Burrell, F. R. Brushett, L. Zhang, J. Mater. Chem. A
2015, 3, 14971-14976.

Figure 1
Alkaline Organic Redox Flow Battery
Authors: Lin Kaixiang , Chen Qing , Marshak Michael P. , Gerhardt Michael R. , Eisenach Louise A. , Gordon Roy G. , Aziz Michael J. 
Published: February 2020

We report a high performance aqueous redox flow battery employing inexpensive, stable and non-toxic organic materials in alkaline electrolyte. An anthraquinone in the negative electrolyte paired with ferro/ferricyanide in the positive electrolyte results in an open circuit voltage of 1.2 V, a peak galvanic power density exceeding 0.7 W/cm2, and a membrane crossover rate three orders of magnitude lower than with inorganic redox couples [1]. Additionally, a redox-active non-quinone organic negative electrolyte, prepared from a single-step coupling reaction of inexpensive bulk commodity chemicals, exhibits an open-circuit voltage exceeding 1.15 V against ferro/ferricyanide. This molecule has a room temperature solubility of 4 M electrons, yielding a charge density of organic negative electrolyte of 108 Ah/L.
[1] K. Lin, Q. Chen, M.R. Gerhardt, L. Tong, S.B. Kim, L. Eisenach, A.W. Valle, D. Hardee, R.G. Gordon, M.J. Aziz and M.P. Marshak, "Alkaline Quinone Flow Battery", Science
349, 1529 (2015)
Aqueous Redox Flow Batteries Based on a Nitroxyl Radical Compound
Authors: Orita Akihiro , Verde Michael , Sakai Masanori , Meng Ying Shirley 
Published: February 2020

We report on novel aqueous redox flow batteries (RFBs) based on 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL) as an active material. TEMPOL is a stable and highly water-soluble nitroxyl radical compound. Electrochemical and UV-VIS measurements highlight that the pH value of electrolyte has a significant impact on the redox reversibility of TEMPOL. The half-wave potential of TEMPOL was determined to be 0.61 V vs. Ag/AgCl (0.83 V SHE.). Furthermore, its peak separation of 73 mV at a sweep rate of 10 mV s-1 is close to the theoretical value (59 mV) expected for a reversible one-electron reaction. We demonstrate that the diffusion coefficient of TEMPOL in neutral aqueous solution is comparable to the vanadium ions used in practical RFBs. TEMPOL also exhibits a quasi-reversible redox reaction, defined by a distinct kinetic rate constant, in near-neutral aqueous solutions.
We show that RFBs incorporating TEMPOL catholyte and Zn-based anolyte have an average discharge voltage of 1.46 V and an energy efficiency of 80.4% during the initial cycle, when subject to a constant current of 10 mA cm-2. We also introduce a green aqueous RFB using TEMPOL catholyte and anthraquinone-2,7-disulfonic acid disodium salt (AQ27Na2) as anolyte. This green RFB contains no toxic or flammable compounds, and exhibits an open-circuit voltage of 1.22 V and an average discharge voltage of 0.74 V. The TEMPOL/Zn and TEMPOL/AQ27Na2 RFBs both show stable and long-term cycling at 10% SOC. Our approach offers a promising direction to develop inexpensive, environmentally-friendly, and safe RFBs.
Molecular Transport through Ion-Selective Membranes in Quinone-Based Redox Flow Batterie
Authors: Chen Qing , Eisenach Louise A. , Valle Alvaro W. , Gerhardt Michael R. , Wong Andrew A. , Beh Eugene S. , Aziz Michael J. 
Published: February 2020

The use of organic molecules such as quinone/hydroquinone in a redox flow battery (RFB) is a promising path toward inexpensive grid-scale electricity storage [1,2]. Because of their relatively large size, the molecules also provide the opportunity to mitigate capacity loss associated with active material crossover that is encountered in RFBs that utilize vanadium ions or bromine. Here we first discuss the effect of crossover on cell performance metrics, including current efficiency, energy efficiency, and capacity retention. We quantitatively compare the impacts from crossover and other loss mechanisms, such as leakage and molecule decomposition in a quinone-bromide RFB [3]. By using UV-Vis spectroscopy in a concentration-driven crossover cell, the crossover rates of different quinone molecules through ion-selective membranes are measured. The rate of crossover is shown to depend on the molecular structure and net charge of the migrating species. The results provide valuable insights with regard to molecule and membrane selection enabling molecular crossover through ion-selective membranes to be effectively minimized.
References:
1. B. Huskinson, M. P. Marshak, C. Suh, S. Er, M. R. Gerhardt, C. J. Galvin, X. Chen, A. Aspuru-Guzik, R. G. Gordon, and M. J. Aziz, Nature, 505, 195–8 (2014).
2. K. Lin, Q. Chen, M. R. Gerhardt, L. Tong, S. B. Kim, L. Eisenach, A. W. Valle, D. Hardee, R. G. Gordon, M. J. Aziz, and M. P. Marshak, Science, 349, 2013–2016 (2015).
3. Q. Chen, L. Eisenach, and M. J. Aziz, J. Electrochem. Soc., 163, A5057–A5063 (2016).
Dynamic Chemical Expansion of Thin Film Non-Stoichiometric Oxides at Extreme Temperatures
Authors: Swallow Jessica G. , Kim Jae Jin , Maloney John M. , Chen Di , Smith James F. , Bishop Sean R. , Tuller Harry L. , Van Vliet Krystyn J. 
Published: February 2020

Thin film non-stoichiometric oxides are of interest as electrodes and electrolytes in electrochemical energy conversion devices including solid oxide fuel cells and electrolyzers because of their potential to lower device operating temperatures and as model systems to aid in investigating rate limiting kinetics. Many of these non-stoichiometric oxides undergo chemical expansion, or composition-dependent volume change, upon ‘breathing’ of oxygen that can result from variations in temperature, oxygen partial pressure, and electrical bias. However, thin film responses are not always accurately predicted based on bulk models or experiments. Understanding the time-resolved operando chemical expansion of non-stoichiometric oxide thin films is essential for modeling and predicting the development of stress and strain in actual devices during temperature excursions or gas interruption. In this work, we report a novel method for measuring chemical expansion of thin films of non-stoichiometric oxides at temperatures up to 650°C and demonstrate its application to the model fluorite-structured system (Pr, Ce)O2-δ (PCO). In this technique, we vary the oxygen activity of the material of interest by applying an oscillating electrical bias across a supporting yttria stabilized zirconia (YSZ) electrolyte, and use a high-temperature, depth-sensing instrumented indenter to detect the amplitude and phase lag of the material’s expansion response, allowing us to characterize nm-scale chemical expansion in PCO films with sub-second-scale resolution. We relate the observed frequency and temperature-dependent response to fundamental processes governing expansion kinetics and compare our results with available defect models for PCO. This ‘electrochemomechanical spectroscopy’ provides an accessible means of characterizing how factors such as film thickness, composition, or microstructure, influence the operando chemomechanical deformation of non-stoichiometric oxide-based devices on short time scales.
(Invited) LLZO Ceramic Electrolytes: A Path Forward to Solid-State Batteries?
Authors: Doeff Marca , Cheng Lei 
Published: February 2020

The appeal of solid-state batteries is clear; there are no flammable liquid components to leak or catch fire, and the possibility of using lithium anodes suggests that higher energy density than currently obtainable with Li-ion configurations should be possible. The emergence of garnet-structured electrolytes based on Li7La3Zr2O12 (LLZO) are particularly attractive for such devices because of their high conductivities and apparent stability against lithium. Still, there are many challenges associated with LLZO, including difficulties in densifying the materials and high interfacial resistances at the lithium electrodes. Work in our group has been directed towards overcoming these obstacles. Classical ceramics processing techniques have been used to produce samples up to 94% dense, as thin as 200 microns, with excellent control over grain size and grain boundary chemistry. Synchrotron techniques such as soft x-ray absorption spectroscopy (XAS) and x-ray photoemission spectroscopy (XPS) reveal that the main culprit leading to high interfacial resistance at lithium electrodes is lithium carbonate, either present as a by-product of synthesis or produced upon exposure to air. Polishing in inert atmosphere removes this impurity and lowers the interfacial impedance, but is not practical commercially. Through grain boundary engineering, it is possible to substantially reduce the sensitivity of samples to air exposure, greatly reducing the tendency towards formation of lithium carbonate and resulting in much lower interfacial impedances at lithium electrodes.
(Invited) Mechanical Stabilty of Solid Electrolyte Interfaces in Solid-State Batteries
Authors: Sakamoto Jeff 
Published: February 2020

Solid-state electrolytes and solid-state batteries have recently garnered significant interest to enable unprecedented performance and safety. While in theory, the performance of solid-state batteries is appealing, in practice numerous manufacturing and cell design challenges are expected owing to the brittle nature of ceramic-based solid electrolytes. To address these challenges, the mechanical properties of solid electrolytes must be characterized. The purpose of this work is to characterize the salient properties of promising oxide and sulfide solid electrolytes to facilitate their transition into the manufacturing and testing of solid-state battery prototypes. Mechanical properties such as the elastic and shear moduli, Poisson’s ratio, fracture toughness, and hardness are presented and their implications discussed. Additionally, a novel approach to conduct in situ, non-invasive, non-destructive mechanical characterization during and after cycling solid-state prototype cells will be presented.
Lithium Chemical Potential Change in Lithium Ion Battery Cathodes Under Mechanical Strain
Authors: Amezawa Koji , Funayama Keita , Kimura Yuta , Mahunnop Fakkao , Nakamura Takashi , Kuwata Naoaki , Kawamura Junichi , Kawada Tatsuya 
Published: February 2020

In solid-state ionic devices, such as all-solid-state lithium ion batteries (LIBs) and solid oxide fuel cells (SOFCs), mechanical strain might be induced at the electrode/electrolyte hetrointerfaces during the cell fabrication process and the operation because of differences in the crystal structures and the chemical/thermal expansion coefficients. Such mechanical strain at the heterointerfaces might affect thermodynamic and kinetic properties of the electrodes and the electrolyte, resulting in deterioration or improvement of the devices’ performance.
In this work, we investigated the influence of mechanical strain on lithium chemical potential in cathode materials for LIBs. Dense thin film electrodes, such as LiCoO2 and LiFePO4, were fabricated on a solid-state lithium ion conductor, such as Li0.29La0.57TiO3 (LLT) and Li7La3Zr2O12 (LLZ). The change in the lithium chemical potential in the electrode was evaluated by measuring electromotive force (EMF) between the electrode under compressively- or tensely-strained condition and one under stress-free condition.
A clear EMF was generated when a mechanical strain was applied to the electrode. Typically, a positive and negative EMF was observed for a compressive and tensile stress, respectively. When the mechanical strain was released, EMF returned to zero. EMF seemed to increase proportionally with increasing the amount of mechanical strain. Such an EMF accompanied with the mechanical strain was discussed from thermodynamic points of view and, as results, could be related to the lithium partial molar volume of the electrode material.
References
[1] K. Funayama, T. Nakamura, N. Kuwata, J. Kawamura, T. Kawada, K. Amezawa, Electrochemistry, 83(10), 894-897 (2015).
[2] K. Funayama, T. Nakamura, N. Kuwata, J. Kawamura, T. Kawada, K. Amezawa, Solid State Ionics, in press.
Water Distribution Oscillations in a PEMFC Under Low Cathode Humidification: Neutron Imaging and Transient Two-Phase Modeling
Authors: Sanchez Daniel G , Boillat Pierre , Biesdorf Johannes , Forner-Cuenca Antoni , Cochet Magali , García-Salaberri Pablo A. , Vera Marcos , Friedrich K. Andreas 
Published: February 2020

Water management is one of the most relevant issues for the successful operation of Polymer Electrolyte Membrane Fuel Cells (PEMFCs). An excessive humidification of the inlet gas streams produces an accumulation of liquid water in the porous electrodes, which hinders the transport of reactants towards the active catalyst sites, thereby decreasing cell performance (an effect known as flooding). On the other hand, an insufficient level of humidification lowers the ionic conductivity of the membrane, also leading to a performance reduction. The complex water management further challenges the transient operation of PEMFCs, so that fast changes of the humidification conditions should be avoided as far as possible.
Previous work has shown the existence of periodic oscillations between high- and low-current density levels in cells operated with dry cathode and fully humidified anode streams1, 2. This oscillatory behavior is associated to the periodic wetting (ignition) and drying of the membrane. The ignition process is caused by the transient accumulation of liquid water at the anode inlet, which is then transported downstream the channel. This leads to a rehydration of dried, deactivated areas of the cell, thereby decreasing the membrane (high frequency) resistance. The ignition process is then followed by a progressive drying of the membrane, so that the ignition/drying (high-/low-current density) cycle repeats itself again and again.
In this work, the spatio-temporal distributions of liquid water during both ignition and drying processes have been visualized using in-plane high-resolution neutron imaging3. Two MEAs with different membranes (Nafion® 111 and Nafion® 117) were investigated to assess their impact on the transient distribution of water throughout the cell. In addition, the experimental data have been compared with the predictions of a transient two-phase macroscopic model. The combined experimental and numerical investigation conducted in this work-in-progress will provide insight on the complex water transport phenomena that take place in operating PEMFCs.
References

1. D. G. Sanchez, D. G. Diaz, R. Hiesgen, I. Wehl, and K. A. Friedrich, J. Electroanal. 635 Chem., 649, 219 (2010).
2. D. G. Sanchez, A. Ortiz, and K. a. Friedrich, J. Electrochem. Soc., 160, F636 (2013).
3. P. Boillat, G. Frei, E. H. Lehmann, G. G. Scherer, and A.Wokaun, Electrochem. Solid St., 13, B25 (2010).
3-D Inkjet Printed Electrode Microstructures for Solid Oxide Electrolysers and Fuel Cells
Authors: Kleiminger Lisa , Farandos Nick , Kelsall Geoff H. 
Published: February 2020

Increasing contributions of renewable energy sources to electrical power grids necessitates the development of advanced energy storage technologies. Reversible high temperature solid oxide electrochemical reactors are one possible solution, whereby surplus electrical energy can be converted into chemical energy in electrolyser mode and re-converted into electrical energy in fuel cell mode as power demand peaks.
Increasing the densities of triple phase boundaries (electrode | electrolyte | reactant gases in pores) at which the electrochemical reactions occur, increases energy conversion efficiencies of solid oxide fuel cells (SOFCs) and electrolysers (SOEs). Electrode structures based on infiltrated-scaffolds have enhanced triple phase boundary densities and better pore size control than those from conventional fabrication methods such as powder mixing. However, fabricating scaffolds reproducibly and predictably at micrometre scales is challenging. Hence, we used a 3D inkjet printer (Ceradrop X-Series) with three multi-nozzle print heads, to produce scaffolds with achievable feature size resolutions of ca. 30 μm in the horizontal plane and 1 μm in the vertical direction (Figure 1A).
For printing SOFCs and SOEs, we developed a printable yttria-stabilised zirconia (YSZ) colloidal dispersion (‘ink’) with sub-micrometre precursor particles. This ink was used to print gas-tight YSZ electrolytes ca. 8 mm thick onto ‘green’ NiO-YSZ substrates, on top of which we printed arrays of micro-pillars with ca. 100-120 μm diameter. The printed cells were heat treated at 600 °C to combust organic additives stabilising particles against aggregation, followed by sintering at 1500 °C. The micro-array was then infiltrated with a 1 molar aqueous nitrate precursor solution of La0.8Sr0.2MnO3-
δ(LSM). Following multiple infiltrations and decomposition of nitrates at 500 °C, the entire cells were calcined at 1100 °C to form the LSM positive electrode (Figure 1B).
Electrochemical performances of these cells with tailored microstructures will be presented for electrolyser and fuel cell modes, for various operating temperatures and gas mixtures (e.g. CO2, H2O, CO, H2).

Figure 1
(Invited) In Operando Studies of Chlorine Induced Anode Degradation in SOFCs Operating with Methane and Biogas
Authors: Walker Robert A , Reeping Kyle W. , Bohn Jessica , Owrutsky Jeffrey C , Qadri Syed Noorullah , Kirtley John D. , Steinhurst Daniel A 
Published: February 2020

Vibrational Raman spectroscopy, IR emission spectroscopy and near IR thermal imaging coupled with voltammetry and impedance measurements was used to explore the effects of chlorine on electrolyte supported solid oxide fuel cell (SOFC) performance and durability. Ni-YSZ SOFC anodes were exposed to 110 ppm dry CH3Cl at 650°C and 700˚C for up to four hours while intermittently exposing the cell to either methane (CH4) or a biogas surrogate (methane/carbon dioxide; 50:50 by mole fraction) for ten minute intervals. In these experiments Raman spectroscopy was used to monitor carbon accumulation kinetics. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements performed with cells at 650˚C operating with CH4 (and exposed to CH­3Cl) showed marked degradation. Degradation with biogas was even more aggressive. In both instances, degradation was irreversible as removal of the chlorine source did not result in complete recovery of performance. These findings stand in contrast to previously reported results of SOFCs operating with H2 in the presence of a chlorine contaminant. Curiously, at 700˚C degradation slows significantly with cell performance diminishing slightly before reaching an asymptotic limit. These results suggest that the presence of carbon facilitates formation of volatile nickel chloride species resulting in substantive damage to anode microstructure.