bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Coin Cell Preparation and Testing Protocols on Coulombic Efficiency Measurements
Authors: Jiang Kyle S. , Gallant Betar M. 
Published: September 2023

The lithium (Li) metal anode holds great promise for high energy-density rechargeable batteries due to its high gravimetric capacity (3860 mAh/g), an order of magnitude larger than graphite at a similar electrochemical potential (-3.040 V vs SHE for Li). However, limited Coulombic efficiency (CE), caused by the thermodynamic instability of conventional Li-ion electrolyte solvents and salts with Li that leads to unstable solid-electrolyte interphase (SEI) during repeated plating and stripping, has hindered the commercialization of Li metal batteries. Research efforts have focused on tuning the electrolyte composition to promote a stable SEI that simultaneously blocks continuous side reactions and electronic conductivity while facilitating Li+ transport [1], with coin cells being by far the most preferred form factor for evaluating these electrolyte designs.
Coin cells enable accessible and rapid testing of diverse electrolyte compositions. Their preparation requires no specialized equipment beyond an inert chemical environment, a crimping mechanism to seal the cell, and modest quantities of Li metal (~50 - 100 μm thickness) and electrolyte (~50 - 100 μL volume) [2]. Despite these attractive features, the procedures for preparing and techniques for measuring CE in coin cells are not fully standardized. In this presentation, we examine the impact on measured CE from preparation and testing procedures, including the internal coin cell stack consisting of components such as the electrodes, current collectors / spacers, and separators, and the cycling protocol. While the cycling protocol and cycling capacity are known to affect capacity loss mechanisms in Li metal batteries [3], we show that variances in CE can additionally be attributed to specific details of cell preparation. In particular, the working electrode area and stack thickness affect the pressure magnitude and uniformity inside the cell. We demonstrate that standardizing the procedures for preparing coin cells reduces variation due to nonuniformities and edge effects and hence improves the reproducibility of CE measurements.
[1] Hobold, G. M., et al. Nature Energy
2021
6 (10), 951-960.
[2] Xiao, J., et al. Nature Energy
2020
5 (8), 561-568.
[3] Adams, B. D., et al. Advanced Energy Materials
2018
8 (7), 1702097.

Figure 1
High-Entropy Oxides as Nanozymes for Non-Immunological Electrochemical Monitoring of Cortisol
Authors: Yin Ziyu , Clark Kaylee , Ray Tyler R 
Published: September 2023

High entropy oxides (HEOs) are a class of materials that have garnered significant attention in recent years due to their potential use as catalysts in energy-related applications[1]. These materials are derived from high entropy compounds, which consist of equimolar or near equimolar ratios of multiple primary elements and have configurational entropy in the formation of a single-phase structure. The cocktail effect of HEOs gives rise to various catalytically active sites due to the synergistic interaction of the different elements, and lattice distortion during the formation of a single-phase solid solution results in the generation of abundant oxygen vacancies, which enhances the adsorption activity of HEOs and improves their catalytic performance[2]. HEOs can also be cost-efficient by utilizing low-cost transition metal elements as their active centers. Despite their widespread use as catalysts, the application of HEOs in electrocatalysis for molecule monitoring and early diagnosis remains largely unexplored.
Cortisol, a glucocorticoid hormone that regulates many aspects of metabolism, stress, and immune response, is closely related to various diseases and disorders[3]. Current methods for noninvasive monitoring of cortisol relies upon immunological assays and typically limited to labor-intensive and time-consuming laboratory techniques. As a consequence, detecting cortisol in a label-free manner that is low cost and offers significant sensor stability and high sensitivity is desirable for many emerging applications, particularly for on-body monitoring.
Here, we present work that examines the catalytic activities of HEOs as nanozymes for the electrocatalysis of cortisol. The electrochemical cortisol sensor is based on a novel one-pot microwave-assisted reaction synthesized (Fe, Co, Mn, Ni, Cu) Ox. The catalytic mechanism of electrochemical sensors depends on the formation of various valence metal redox species pairs, where the higher valence state oxidizes cortisol species present on the electrode surface, accompanied by a reduced lower valence state. The one-pot microwave-assisted synthesized HEOs exhibited ultra-high catalytic activity towards cortisol species as measured by cyclic voltammetry and chronoamperometry. Experimental results show a superior sensing performance including a detection limit as low as 0.5 µM (s/N=3), a good linear detection range between 0.01 ~ 4.01 µM, and a sensitivity of 46.5 µA µM-1 cm-2.

References:

[1] Y. Pan, J.-X. Liu, T.-Z. Tu, W. Wang, and G.-J. Zhang, “High-entropy oxides for catalysis: a diamond in the rough,” Chem. Eng. J., p. 138659, 2022.
[2] D. Feng et al., “Holey lamellar high-entropy oxide as an ultra-high-activity heterogeneous catalyst for solvent-free aerobic oxidation of benzyl alcohol,” Angew. Chem., vol. 132, no. 44, pp. 19671–19677, 2020.
[3] B. Wang et al., “Wearable aptamer-field-effect transistor sensing system for noninvasive cortisol monitoring,” Sci. Adv., vol. 8, no. 1, p. eabk0967, 2022.
Clarification of the Reaction Mechanism of the Photoassisted Anodic Oxidation of SiC in a Newly Developed Inverted Rotating Disk Electrode Cell Setup
Authors: Mairhofer Katharina , Larisegger Silvia , Fafilek Guenter 
Published: September 2023

Due to the distinctive chemical and physical properties of silicon carbide (SiC), interest in the material as a substrate for semiconductor industry has risen significantly during the past two decades. As a wide bandgap semiconductor SiC is known to be highly chemically inert. Still, under specific conditions SiC takes part in a number of electrochemical reactions that lead to a rapid oxidation of the surface. The goal of this work is to understand the fundamental factors driving this process for n-type SiC crystals in aqueous electrolytes.
In alkaline solutions, the photoelectrochemical behaviour of n-type SiC is determined by two partial reactions (oxidation/dissolution)
1
:
(1a) SiC + 6h+ (hν) + 6OH- → SiO2 + CO + 3H2O
(1b) SiC + 8h+ (hν) + 8OH- → SiO2 + CO2 + 4H2O
(2) SiO2 + 2OH- → [Si(OH)2O2]2-

For the investigation of such photoassisted or photoelectrochemical reaction mechanisms involving mass transfer, we specifically developed a new inverted rotating disk electrode (IRDE) cell setup
2
that allows to control the most essential experimental parameters (i.e. potential, diffusion conditions and light intensity).
In this setup, rotation of the disk electrode is achieved by magnetic coupling between a driver magnet (i.e. a magnetic stirrer) and the follower magnet included in the sample holder. The cell allows a homogeneous illumination and removal of gaseous reaction products, while still providing leak tightness. The surface of the semiconductor electrode is illuminated with UV light (λ = 365 nm) from a high-power LED. The distance between light source and sample is minimized to achieve maximum surface illumination of the sample.
To investigate mass transport phenomena, electrolytes with relatively low solubility of SiO2 are preferable. Therefore, we used potassium hydroxide solutions in a concentration range where mass transport of hydroxide ions plays a major role.
Performing cyclic voltammetry in this newly developed IRDE cell allows to distinguish different reaction regimes that are either limited by mass transport, photon flux or hole transport. For low light intensities (either through a large distance between the sample and the LED or through low driving currents through the LED) the number of photon-induced holes is limiting. At low electrolyte concentrations, the transport of hydroxyl ions and the dissolution of the oxidation products determine the reaction rate. At low potentials, hole transport limits the overall current flow. Each of these reaction regimes was studied individually to conduct a potential reaction mechanism.
[1] D. H. van Dorp und J. J. Kelly, „Photoelectrochemistry of 4H–SiC in KOH solutions,“ Journal of Electroanalytical Chemistry, Bd. 599, Nr. 2, pp. 260-266, 2007.
[2] K. Mairhofer, P. Mayr, S. Radl, M. Nelhiebel, S. Larisegger, G. Fafilek, „An Inherently Leakage-Free Inverted Rotating Disk Electrode Setup“, 2022.

Figure 1
Mixed Isomer Chromium-Chelates for High Concentration Aqueous Flow Battery Electrolytes
Authors: Davis Casey M. , Waters Scott E. , Robb Brian H. , Thurston Jonathan R. , Reber David , Marshak Michael P. 
Published: September 2023

Redox flow batteries have attracted attention for their potential for large-scale energy storage, largely due to their ability to decouple power and energy. However, their limited energy density is often cited as a major drawback preventing adoption at scale. Therefore, there is interest in research into increasing the solubility of the active material in these electrolytes. One such method is active materials with multiple redox events. Promising materials are, however, often poorly soluble, and computational studies showed that increasing differences in redox potential between e.g., two redox events will decrease the energy efficiency of the cell.1 Here, two Cr-chelate structural isomer complexes, with redox potentials 100 mV apart are characterized and compared electrochemically. The two chromium complexes are combined in mixed-anion electrolytes to generate an electrolyte of 2 M active species, corresponding to a capacity of 53.6 Ah L−1, significantly higher than the individual isomers could achieve. At 100 mA cm−2 the cell achieved average Coulombic efficiencies of 99.6% and an equilibrium cell potential of 1.65 V at 50% State-of-Charge. Due to high viscosity of the electrolyte, the voltaic efficiency was only 67%. At a 1 M concentration, the equimolar mixed-anion electrolyte had a comparable current efficiency to the individual Cr-isomers (within 0.2%) but lowered voltaic efficiency (75.8% compared to 77.8% and 78.6%). The lowered voltaic efficiency is attributed to inefficiencies caused by non-concerted multiple redox events. The high cell voltage and increased combined electrolyte capacity demonstrate that employing chirality, chelate geometry, and structural isomers in a mixed-anion approach can significantly increase overall active material concentrations, but that there are consequences for cell performance when using multiple molecules with disparate reduction potentials in an electrolyte. This highlights that concerted transitions should be prioritized in order to capitalize on multi-electron redox species.
References:
(1) Neyhouse, B. J.; Fenton, A. M.; Brushett, F. R. Too Much of a Good Thing? Assessing Performance Tradeoffs of Two-Electron Compounds for Redox Flow Batteries. J. Electrochem. Soc.
2021, 168 (5), 050501. https://doi.org/10.1149/1945-7111/abeea3.
Enhanced Performance of Recovered Cathode Materials with Fluorine Impurity in Hydrometallurgy Recycling
Authors: Zheng Yadong , Wang Yan 
Published: September 2023

With the growing lithium-ion battery (LIB) industry since its initial inception in the late 20th century, battery recycling is seen as an end-of-pipe process to resolve environmental and economic issues generated by the accumulation of waste batteries. In recent years, an increasing attention has been paid to the hydrometallurgy recycling due to its high recovery efficiency, low energy cost, as well as large-scale production capability. In order to achieve a high-quality recovered material, many resources have been poured into this field trying to develop better design and control of synthesis process. The impurities introduced in the recycling process is an important factor which could have unintended impacts on the final cathode product in a variety of aspects. The presence of fluoride ions in hydrometallurgy recycling, as one possible anion impurity which is released from the LiPF6 in electrolyte, aroused our research interest. In this work, the influence of the fluorine impurity on the recovered LiNi0.6Co0.2Mn0.2O2 (“NCM622”) cathode material via hydrometallurgy method is systematically investigated. The results show that the addition of fluorine impurity in the hydrometallurgy process improves the electrochemical properties of the recovered cathode materials.
It is found that the fluorine impurity has lots of positive impacts on the synthesized cathode materials. First of all, the equilibrium of co-precipitation reaction is affected by the fluoride ions, resulting in the formation of holes in hydroxide precipitates. After sintering, cathode particles preserve a hollow structure which leads to an improved rate capability and cycle stability. In addition, surface oxygen sites of cathode materials are found to be substituted by impurity fluoride ions. As a result, an increased surface Ni2+ concentration contributes to a better cathode surface stability as well as a higher reversible capacity. The inclusion of fluoride (<1 at%) in cathode lattice is also beneficial to the bulk lithium-ion diffusion. Not only that, but the fluorine impurity has no clear detrimental effects on the particle morphology, crystal structure, transition metal composition, and element distribution of the cathode materials. Therefore, the electrochemical performance of synthesized cathodes has achieved different levels of improvement due to those positive influences from the fluorine impurity. Specifically, cathode with 0.2 at% impurity exhibits a discharge capacity of ~168 mAh/g with a remarkable retention of 98% at 1/3C after 100 cycles, about 8% higher than the capacity of virgin benchmark. Also, rate test outcomes of fluorine-affected samples are superior to that of virgin standard. In summary, the electrochemical properties of recovered cathode via hydrometallurgy process can be boosted by fluorine impurity. Unlike adverse impurities, fluoride’s positive role in hydro-recycling indicates that it is no need to strictly control them in pre-treatment steps.

Figure 1
Cathode Development for All Solid-State Lithium-Sulfur Batteries
Authors: Lopez Gonzalez Daniela , Neburchilov Vladimir , Tsay Ken , Gyenge Elod 
Published: September 2023

With higher demand for alternative energy sources that are cleaner and more sustainable, research has shifted towards various lithium metal-based batteries with higher capacities than lithium-ion (LIBS). The study of lithium-sulfur energy storage systems has been heavily influenced due to the high gravimetric capacity of sulfur (1672 mA h g−1) and its abundance in the Earth’s crust. To increase the safety of lithium-sulfur batteries, solid state systems have been developed. These systems are also advantageous as the polysulfide shuttle effect normally seen in organic liquid electrolytes (OLEs) is eliminated, decreasing degradation due the irreversible reactions. Some of the most successful electrolytes found for lithium-sulfur all solid-state batteries (ASSLSBs) are ceramic based electrolytes. These electrolytes have high ionic conductivities (ranging 10-3-10-4 S cm-1) and do not pose any safety risks. However, one of the biggest bottlenecks of ASSLSBs is the utilization and accessibility of sulfur during cycling.
To ensure these attributes are met, carbon materials have been used as supports; additionally, carbon also aids in electron transport due sulfur’s low electrical conductivity (10 -15 S m-1).
Sulfur is typically dispersed or deposited on these carbon supports in different approaches before a full cathode composition is developed. Varying synthesis methods of sulfur deposition onto reduced graphene oxide are studied to determine which synthesis method provides the most accessibility for sulfur utilization. Utilization and accessibility will be analyzed through cyclic voltammetry, galvanostatic charge and discharge and impedance measurements to obtain characteristic voltammograms, specific capacity curves and Nyquist plots. Cells are assembled in PEEK Split cells using ceramic based electrolyte and lithium metal for the development of a noble ASSLSB.
Characterizing Mg2+ Conduction in Metal-Organic Frameworks
Authors: Wang Yang , Luo Tongtong , Elander Brooke , Mu Yu , Wang Dunwei , Mohanty Udayan , Bao Junwei Lucas 
Published: September 2023

Next generation solid-state materials for fast ion conduction have the potential to revolutionize battery technology. Metal-organic frameworks (MOF) are a promising material for achieving this goal. Given their structural diversity and complexity, design of efficient MOF-based ion conductors can be accelerated by detailed understanding and quantitative prediction of ion conductivity. To this end, the chemical behavior and transport properties of an Mg(TFSI)2/DME electrolyte system inside Mg-MOF-74 were studied by a combination of computational and experimental methods.The dominant minimum energy pathway (MEP) for Mg2+ conduction inside Mg-MOF-74 was found to be “solvent hopping” mechanism, with an energy barrier of 4.4 kcal/mol.
However, due to the polycrystalline nature of solid-state materials, specifically MOF-74 in our case, grain boundary effects need to be taken into consideration, which is complicated by challenges in grain boundary characterization, as well as modeling of ensemble transport properties. To address these issues, we developed an approach for modeling ion transport at grain boundaries and predicting their contribution to conductivity. In particular, Mg2+ conduction in Mg-MOF-74 thin film was studied as a representative system. Using computational techniques and guided by experimental data, we investigated the structural details of MOF grain boundary interfaces to determine accessible Mg2+ transport pathways. Computed transport kinetics were input into a simplified model of the MOF nanocrystal, which combined ion transport in bulk structure and at grain boundaries. The model was able to predict Mg2+ conductivity in MOF-74 thin film within chemical accuracy (<1 kcal/mol difference for apparent activation energy), validating our approach. The results indicate that Mg2+ conduction in MOF-74 is inhibited due to strong Mg2+ binding at grain boundaries. Only favorable alignments of the grain boundary interface allow for fast Mg2+ transport through MOF and contribute notably to ion conductivity. The relative scarcity (~0.1% frequency) of these favorable alignments results in a reduction of conductivity by 2-3 orders of magnitude, illustrating the large impact of the grain boundary contribution. Grain boundary structure and its interaction with ions are critical for a molecular-level understanding of solid-state ion transport and quantitative prediction of conductivity.
Our work provides a computation-aided synergistic platform for quantifying the role of grain boundaries in mediating ion transport, which can serve as a complementary characterization tool for the solid-state ion conductor community and providing insights for MOFs’ application in Mg battery area.
(Keynote) Aerogel-Derived Nickel-Iron Oxide Catalysts for Oxygen Evolution Reaction in Alkaline Media
Authors: Osmieri Luigi , Yu Haoran , Myers Deborah J. , Cullen David A. , Zelenay Piotr 
Published: September 2023

Low-temperature alkaline water electrolyzers, both liquid alkaline and—more recently—anion exchange membrane (AEM) ones, represent an attractive path towards large-scale generation of green hydrogen, possibly without relying on precious metals, otherwise required by the competing proton exchange membrane (PEM) electrolyzer technology. Of the two alkaline systems, the AEM electrolyzer offers an additional benefit of not needing highly concentrated alkaline solutions and, upon further development, possibly not requiring any electrolyte at all. The ultimate success of the AEM technology will depend though on progress in the development of several key materials: alkaline exchange membranes, electrode ionomers, and platinum group metal-free (PGM-free) electrocatalysts for the anode and the cathode. It will also depend on successful integration of the developed materials into a complete device, aiming especially at well-performing catalyst/membrane and catalyst/ionomer interfaces that are free of significant charge and mass transport losses.
The focus of this work has been on NiFe oxide electrocatalysts for oxygen evolution reaction (OER) for alkaline media in low temperature electrolyzers. The catalysts have been derived from aerogels heat-treated at different temperatures. Depending on the synthesis temperature the catalysts have shown dissimilar OER activities and morphologies, required different activation procedures and incurred diverse structural changes during testing. In addition to extensive performance evaluation in a three-electrode electrochemical cell and a small electrolyzer, the catalysts have undergone wide-ranging physicochemical characterization with the purpose of identifying causes of the differences in their activity and performance durability. Characterization involved among others high-resolution scanning microscopic techniques and electron and X-ray spectroscopy methods (e.g., EELS, XPS, EXAFS/XANES).
Of special interest in this research has been the development and optimization of catalyst activation approaches, both in-situ (in an operating cell) and ex-situ. The effect of ionomer type on catalyst performance and overall performance of NiFe catalysts in electrolyzer-type electrodes has been studied, too, and will be summarized in this presentation.

Acknowledgement

This work has been performed as part of catalyst development efforts in Electrocatalysis Consortium (ElectroCat), funded by U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) via Hydrogen and Fuel Cell Technologies Office (HFTO).
(Keynote) Electrochemical CO2 Reduction on NiNC Single Metal Atom Catalysts Under Alkaline to Acidic pH Conditions
Authors: Strasser Peter 
Published: September 2023

The science and technology of the direct electrochemical CO2 reduction reaction on both model electrodes in liquid-electrolyte H-cells and Gas Diffusion Electrodes (GDEs) in flow electrolyzers offer as many formidable challenges as intriguing opportunities. Controlling the selectivity (faradaic efficiency), while maximizing the energy efficiency by lowering the kinetic overpotentials remains key to turn this complex reaction into a practical process embedded in a process chain.
In this talk, I will highlight some of our recent advances in the design and characterization of NiNC single site electrocatalysts for the electrochemical reduction of CO2 to CO and CO2/CO mixed feeds into value-added fuels and chemicals in H-cell and Gas Diffusion Electrode (GDE) single cell electrolyzers. Further focus will be placed on the diagnosis of carbonate transport processes during electrolyzer cell operation using the experimentally accessible carbon crossover coefficient, CCC. Performance and its limitations of cell operation in alkaline and acid conditions will be contrasted and discussed.