bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Physical and Analytical Electrochemistry Division Max Bredig Award in Molten Salts and Ionic Liquid Chemistry Address) Unexpected Energy Applications of Ionic Liquids
Authors: MacFarlane Douglas Robert 
Published: December 2024

Ionic liquids (ILs), Ionic liquid Analogues (ILAs) and Organic Ionic Plastic Crystals (OIPCs) are finding a wide range of applications in energy related applications. The advantages of ILs as Lithium battery electrolytes have been explored for many years. In more recent times this has expanded to include IL/ILA type electrolytes for sodium, magnesium and potentially aluminium-based batteries. Other electrochemical applications include thermo-electrochemical cells and as electrolytes in ammonia producing electrolysis cells. Beyond electrochemistry there is great interest in ILs as phase change materials for the storage of thermal energy, including in a novel heat-pump based device known as the Carnot Battery.
Also emerging are a number of “mixture” systems related to ILs that have modified or enhanced properties; these we broadly describe as Ionic Liquid Analogues. In many cases these analogues have lower cost and improved sustainability characteristics than pure ILs.
One the key drivers of further development of ionic liquid chemistries, currently, is the need to focus on sustainability and the circular economy, both in regard to the ionic liquid components themselves as well as their impact on the recycling or repurposing of the bigger system in which they are employed. For example, the growing concern regards PFAS compounds is rendering some ionic liquid ions unsuitable and manufacturers unlikely to continue supplying them.
Many of these applications have emerged in the last decade or so in the period since we wrote a paper entitled “Energy Applications of Ionic Liquids”.1 To reflect on these, somewhat unheralded, developments in emergent fields, we have very recently published an update on that paper.2 This, and the many papers it reviews, forms a key basis for this talk.
(1) MacFarlane, D. R.; Tachikawa, N.; Forsyth, M.; Pringle, J. M.; Howlett, P. C.; Elliott, G. D.; Davis, J. H.; Watanabe, M.; Simon, P.; Angell, C. A. Energy applications of ionic liquids. Energy Environ. Sci.
2014, 7 (1), 232-250, DOI: 10.1039/C3EE42099J.
(2) Karolina Matuszek, S. P., Alina Brzęczek-Szafran, Binayak Roy, Saliha Saher, Jennifer M. Pringle, Douglas R. MacFarlane. Unexpected Energy Applications of Ionic Liquids. Adv. Mater.
2024. DOI: 10.1002/adma.202313023.
Cathode Reaction Studies in Lithium-Oxygen Battery through Operando XRD Measurements
Authors: Dilixiati Dilinigeer , Aoki Makoto , Maeda Kazuno , Kondo Toshihiro 
Published: December 2024

Introduction

The lithium-Oxygen (Li-O2; LOB) battery has obtained significant attention as a promising candidate for next-generation storage batteries due to its higher specific energy density compared to conventional lithium-ion batteries [1]. However, the mechanism of the cathode reaction remains unclear, and the type of Li2O2 produced during cathode discharge is still uncertain, mainly because it's challenging to directly observe the compounds generated at the cathode during LOB operations. By newly designing observation cells and improving laboratory XRD system, we clarified the discharge products and investigated the discharging process using operando XRD measurements and Rietveld refinements[2]. In this study, the cathode reaction mechanism was discussed based on the results of the operando XRD measurements.

Experimental

A newly designed electrochemical cell, covered with a Kapton film dome to enable constant oxygen flow to the cathode side of the LOB, was set to the diffractomator of the Rigaku Ultima IV XRD measurement system. In the XRD system, Cu Kα was utilized as the incident X-ray, and high-speed one-dimensional detector served as the detector. In the electrochemical cell, Ketjen black self-standing films were employed as cathode materials, and tetraglyme solution containing 0.5 M LiTFSI + 0.5 M LiNO3 + 0.2 M LiBr was used as the electrolyte solution. The LOB was discharged and charged at a constant current density of 0.4 mA/cm2 for 10 hours each (4.0 mAh/cm2), in which XRD profiles were recorded every 20 minutes. Rigaku's SmartLab Studio II software was utilized for Rietveld analysis of each XRD profile to determine the detailed cathode product and its crystal structure.

Results and discussion

Upon conducting operando XRD measurements and Rietveld analyses, the cathode reactions of the Li-O2 battery were investigated. The discharging and charging reactions at the cathode of the Li-O2 battery, as well as the x values of the major product Li2-xO2 during discharging, have been investigated and determined. In the XRD profile measured during discharging, several peaks attributed to the cathode product were observed. Detailed Rietveld analysis of these peaks revealed that LiO2 with the same P63/mmc space group structure as Li2O2 was immediately formed after discharge initiation, followed by the deposition of Li2-xO2 accompanied by an increase in lithium occupancy. As discharging progressed, the lattice constant gradually extended towards the c-axis direction, leading to the formation of Li1.5O2 at a discharge capacity of 4.0 mAh/cm2. In this presentation, we will discuss the discharge and charge reactions of the Li-O2 battery cathode in detail, and we will also discuss the charge-discharge cycle characteristics.

References

[1] T. Liu, et al., Chem. Rev.
120, 6558 (2020).
[2] M. Aoki and T. Kondo, et al., J. Phys. Chem. C
127, 15051 (2023).
(Invited) Predicting Interfacial Ion Adsorption, Ion Solvation, and Correlated Ion Transport in Advanced Electrolytes
Authors: Son Chang Yun 
Published: December 2024

Electrostatic interactions plays a dominant role in charged materials systems. Understanding the complex correlation between macroscopic properties with microscopic structures is of critical importance to develop rational design strategies for advanced materials. But the complexity of this challenging task is augmented by interfaces present in the system, requiring a multi-scale approach to incorporate the spatiotemporal resolution needed for molecular descriptors and the interfacial heterogeneity.
In this talk, I’ll present our ongoing efforts to enable predictive molecular simulations of these highly charged systems, especially focusing on the field of developing advanced electrolytes. A key advancement has been made with the development of predictive multi-scale force field for Li+ solvating electrolytes, ionic liquids (ILs), and polymers based entirely on first-principle calculation, as well as novel simulation algorithm to treat the complex surface polarization effect occurring at the conducting electrodes. New physical insights gained from the new simulation model and simulation algorithms will be discussed, which includes simulation study of lithium ion transport under nanoscale confinement formed by microphase separation, and controlling morphology and interfaces to enhance the mechanical and dynamic properties of novel polymer-IL mixture system for energy application.
Operando X-Ray Tomography Measurements of a Membrane Electrode Assembly for Electrochemical CO2 Reduction
Authors: Lee Sola , Jang Myeong Je , Qi Zhiyuan , Paradis-Fortin Laura , Atwater Harry A. , Drisdell Walter S. , Xiang Chengxiang("CX") 
Published: December 2024

The electrochemical reduction of carbon dioxide (eCO2R) holds great promise for producing valuable chemicals and fuels while mitigating carbon emissions. However, challenges arise from the need to enhance CO2 transport and operate at higher current densities. Despite the development of gas diffusion electrodes, operating at higher current densities generates hydroxide ions at the cathode, promoting the formation of carbonate ions, which can cause salt precipitation and flooding, hindering CO2 mass transport.
To investigate the potential degradation of eCO2R of copper gas diffusion electrode (Cu GDE), we utilize X-ray tomography, a nondestructive method for visualizing morphological changes. Through in-line gas chromatography, we track salt precipitation and flooding in the GDE, correlating these changes with shifts in product distribution during eCO2R. Our findings reveal that the degradation of membrane electrode assembly (MEA) cells is linked to the extent of precipitation and flooding. Furthermore, micro-CT imaging captures morphological changes, such as precipitation growth, dissolution, and regrowth from the Cu surface to the gas diffusion layer, during transient oscillatory voltage profiles and selectivity changes in Cu GDE. This study sheds light on the degradation mechanism of MEA cells and offers insights into strategies for enhancing device durability.
Micro-Electrochemical Sensor Array for Detection of Serotonin
Authors: Navaei Milad , Park Jinho , Heist Christopher A. , Swarts Matthew , Young Katherine T. 
Published: December 2024

Chemical and biological threats pose a significant risk to national security, whether arising from natural outbreaks, accidental releases, warfare, or terrorism. Consequently, there's an urgent demand for innovative technologies capable of real-time screening, detection, and forensic analysis, especially concerning chemical warfare agents, explosives, and nuclear monitoring in field operations. Advancements in biosensing have revolutionized the detection of contaminants using diverse techniques. One notable breakthrough involves synthetic biology, which has led to the creation of biosensor devices capable of monitoring chemical and physical contaminants. These devices can conveniently display detected contaminants as visual signals, such as fluorescence and bioluminescence. However, due to lack of the advances in bio-electronics interfaces, these sensors are not ubiquitous for chemical and biological sensing electronic systems.
In this context, we present the development of a Bio engineered microfabricated electrochemical sensor to detect serotonin by producing hydrogen peroxide (H2O2). The study entails COMSOL simulations aimed at understanding the electrochemical behavior of the electrode for detection of H2O2 by identifying relevant physics, determining the necessary parameters for the simulation concerning the solution and materials, and conducting experiments to validate the electrochemical signal, particularly the charge transfer density. Three distinct electrode geometries are explored in this experiment: the unpatterned electrode, the interdigitated electrode, and the ring array electrode. The performance of the ring electrode is experimentally evaluated for its ability to detect H2O2 levels ranging from 0 to 250 parts per million (ppm).
FIPEX: Sensor Kinetics of Thin-Film Solid Electrolyte Atomic Oxygen Sensors for Space Applications
Authors: Hoerner Igor , Eberhart Martin , Loehle Stefan , Fasoulas Stefanos 
Published: December 2024

Atomic oxygen (AOX) quantification in the upper atmosphere of the Earth is of fundamental interest for the understanding of weather and climate development. Solid electrolyte sensors are suitable instruments for this task since they qualify as payload on all common spaceflight systems due to their small size and low power consumption. The High Enthalpy Flow Diagnostics Group (HEFDiG) at the Institute of Space Systems (IRS) (University of Stuttgart, Germany) has been developing solid electrolyte sensors (FIPEX) for applications aboard sounding rockets in the past 12 years.
FIPEX sensors employ YSZ (yttria stabilized zirconia) as solid electrolyte. Together with platinum or gold electrodes they form an electrochemical cell that is operated in an amperometric mode of operation. At elevated temperatures and with a voltage applied between the electrodes this setup forces a migration of oxygen anions through the electrolyte. The corresponding electrical current is measured in an outer circuit and is a function of the AOX flux onto the surface of the sensor.
On sounding rockets, the measurement of atomic oxygen is particularly difficult because of the rocket’s high vertical speed yielding strong gradients in AOX number densities along the trajectory. Therefore, our research focuses on the measurement of sensor response times and their reduction. Initially, FIPEX sensors were manufactured with screen printed electrodes that are robust yet comparably thick. Surface diffusion of adsorbed oxygen atoms at the cathode was identified as the rate limiting step in this configuration. In order to reduce the diffusion length, the screen printed electrodes were replaced by porous thin-film electrodes leading to significantly improved response times.
This contribution focuses on the analysis of the sensor kinetics governing the behavior of the new thin-film FIPEX sensors. We demonstrate how porosity of the initially dense anode is triggered by high polarization. From this, we provide evidence that an increased porosity at the anode is sufficient to improve the response time of a FIPEX sensor. This is different from the conclusions drawn from the analysis of sensors with thicker screen printed electrodes. An experimental configuration to determine sensor step responses to sufficiently fast changes in oxygen particle flux is presented. Above that, we discuss cyclic voltammetry observations to develop a deeper understanding of the underlying kinetic processes.
In conclusion, the transient behavior of thin-film sensors is shown to be dictated by kinetic steps different from what was found for screen printed sensors. Impacts on the suitability and further application of FIPEX sensors in space are presented.
Fig. 1: a) Functional layers of a FIPEX sensor. b) Photography of a FIPEX sensor with thin film electrodes.

Figure 1
(Keynote) Elevating Supercapacitors with Ultrafast Materials: Vital Contributors to Sustainable Energy Solutions
Authors: Naoi Katsuhiko , Naoi Wako 
Published: December 2024

Supercapacitors have emerged as pivotal energy conversion-storage systems in contemporary renewable and sustainable nanotechnology, offering a cost-effective and eco-friendly alternative. With material properties being paramount to their performance, supercapacitors stand out from conventional batteries due to their exceptional high-power capabilities and longevity, making them versatile for various applications. Their remarkable features, such as high-power capabilities and extended cycle-life, make them highly attractive for advanced hybrid configurations, serving both mobile and stationary purposes across diverse applications. The drive to shape the next generation of energy technologies fuels the development of composite materials, integrating elements like nanocarbon/graphene and metal oxides to enhance electrochemical performance.
Material selection plays a critical role in supercapacitors, as different materials used as electrodes and electrolytes significantly influence functionality and characteristics, particularly in determining thermal and electrical properties. Leveraging innovative techniques such as "Ultracentrifugation" and “Spray-Dry Synthesis,” nanoarchitecture electrode materials are engineered for improved performance and safety.
Collaborations with Li-predoping technology experts aim to develop groundbreaking Li-ion-based energy facilitators like the "iE7" SuperRedox Capacitor, capable of seamlessly balancing high power and energy demands. By integrating advancements in material science, pre-doping techniques, and cell design, the vision extends beyond innovation to lead the transition towards solar regeneration, driving electrification, and decarbonization across extensive mobility and heavy-duty sectors.

References:

K. Naoi et al., Adv. Mater.,
28, 6751 (2016); E. Iwama, K. Naoi et al., ACS Nano, 10, 5398 (2016); P. Simon, K. Naoi et al., Nat. Ener., 1, 16070 (2016); K. Naoi et al., Acc. Chem. Res., 46,1075 (2013); K. Naoi et al., Ener. Environ. Sci., 5, 9363 (2012).

K. Naoi et al., Chem. of Mater., 36, 2495 (2024); K. Naoi et al., J. Mater. Chem. A, 12, 2081 (2024); K. Naoi et al., J. Mater. Chem. A, 12, 1703 (2024); K. Fujii, K. Naoi et al., Phys.
Chem. Chem. Phys., 26, 3920 (2024); K. Naoi et al., J. Electrochem. Soc., 170, 010524 (2023); K. Naoi et al., ACS Appl. Ener. Mater., 6, 9, 4657 (2023); K. Naoi et al., J. Mater. Chem. A, 11, 1841 (2023).

Figure 1
(Invited) Synthesis of Structured Transition Metal Sulfide Electrodes Via a Highly Active Sulfur Activation Process for Fast Energy Storage Applications
Authors: Hong John 
Published: December 2024

Transition metal sulfide (TMS) materials exhibit significant potential as high-performance supercapacitor electrodes for rapid charge-discharge cycles. Compared to their oxide counterparts, TMS materials generally show superior electrical conductivities, with the incorporation of sulfur atoms boosting their ionic conductivities.
The fabrication and control of the structure and morphology of TMS electrodes are crucial in determining their physical and electrochemical properties for energy storage applications. Typically, the electrochemical efficiency correlates with the interactions between the electrode materials and electrolyte ions at the electrode's surface. Hence, electrodes with an optimally structured morphology can demonstrate enhanced electrochemical performance due to their increased surface area, reduced ion transport distances, and structural integrity. These characteristics contribute to higher specific capacitance, enhanced ion diffusion kinetics, and extended cyclability.
Electrochemically active electrode materials are typically created with various micro/nanostructures using different synthetic methods, such as solvo-/hydrothermal synthesis, thermolysis, microwave irradiation, chemical vapor deposition, sputtering, and electrodeposition. These synthetic processes often require extended synthesis times (approximately 12–24 hours), electrochemical deposition and additional heat treatment to transform chemical reactants (above 400°C). Such methods impose significant high-temperature input, voltage damage, or mechanical strain on substrates, rendering them impractical for the industrialization of supercapacitors and likely degrading the practicalbility of diverse substrates. Consequently, identifying an effective method to fabricate electrochemically active electrode materials without thermal heat treatment is important. The low-temperature solution-based synthetic approach has been investigated as a viable alternative for depositing active materials on metal substrates.
In this study, we introduce a novel and efficient method for synthesizing hierarchically structured TMS electrodes using a direct exposure approach with a highly reactive sulfide solution. The essence of this synthesis technique lies in the swift interaction between the ammonium sulfide solution and transition metal, wherein the ammonium ions catalyze the liberation of transition metal ions. Subsequently, these released ions react with sulfur ions in the solution, resulting in the formation of TMS materials. By modulating the synthesis conditions, it is possible to engineer TMS electrodes with diverse structures, leading to varying electrochemical properties. This approach offers a simple yet effective pathway to fabricate scalable, hierarchical TMS structures, highlighting the innovative capabilities of the solution-based sulfur activation method for high performance and fast energy storage applications.
(Invited) Fast Proton Storage in Metal Oxide Electrodes for Aqueous Electrochemical Energy Storage
Authors: Okubo Masashi 
Published: December 2024

Lithium-ion batteries (LIBs) dominate the battery market for portable electronics and electric vehicles owing to their long lifetime, high efficiency, and high energy densities. However, LIBs are comprised of flammable and costly organic electrolytes, which unexceptionally accompany both safety hazards and high fabrication costs. Electrochemical energy storage (EES) devices that utilize aqueous electrolytes are expected to provide more operational safety, affordability, high power, and environmental benignity. Although the intrinsically narrow electrochemical stability window for water as an electrolyte solvent (1.23 V) imposed severe limitations on any practical applications of aqueous EES devices, novel strategies involving highly concentrated aqueous electrolytes have achieved much wider electrochemical potential windows (>3 V), thereby paving a path for the development of more practical aqueous EES devices. Importantly, highly concentrated aqueous electrolytes can provide unexpected environments for electrode materials that have been considered ‘useless’ in conventional dilute aqueous electrolytes. I will show our recent attempts to achieve fast proton storage of oxide electrodes in aqueous media.
Reference
1. D. Sun, M. Okubo, A. Yamada, Chem. Sci., 2021, 12, 4450-4454.
2. Z. Ma, et al., M. Okubo, A. Yamada, Adv. Mater. 2022, 34, 2203335.
3. T. Shimada, et al., M. Okubo, A. Yamada, Chem. Mater. 2022, 34, 2069-2075.
4. Z. Ma, et al., M. Okubo, A. Yamada, Adv. Funct. Mater. 2023, 2214466.
水性レドックスフロー電池用アントラキノン系陽極液の機能化
Authors: Kawgauchi Momoka , Okazawa Atsushi , Kawai Kosuke , Okubo Masashi 
Published: December 2024

Redox flow batteries (RFBs) are developed as grid-scale load-leveling technologies for renewable energy. Commercial RFBs use vanadium ions as active materials. However, their low energy density and high cost hinder wide deployment in electrical grids. To address these issues, 2,2′-(anthraquinone-2,6-diyldioxy)dipropionic acid (1Me) was reported as an aqueous anolyte to achieve two-electron redox capability, long cycle life, and high solubility.1 In this work, we improve the cycle stability by introducing a sterically bulkier substituent into the side chain of the anthraflavic acid derivative: 2,2′-(anthraquinone-2,6-diyldioxy)dibutyric acid (1Et; Figure 1).

1Et was synthesized by introducing methyl 2-bromobutyrate into anthraflavic acid, followed by saponification and subsequent neutralization with hydrochloric acid. Both 1Me and 1Et exhibit a redox potential of −0.68 V (vs. Ag/AgCl) in 1 mol L−1 KCl and 0.01 mol L−1 KOH aqueous solutions, indicating little influence of the substituent modification to a redox potential. Interestingly, 1Et shows higher solubility (1.73 mol L−1) than 1Me (1.54 mol L−1) despite an elongated hydrophobic alkyl side chain moiety. An ethyl group possesses a higher degree of freedom for rotation and vibration than a methyl group, resulting in larger dissolution entropy and hence higher solubility. Charge/discharge measurements using an H-type cell reveal that 1Et shows a higher capacity retention (0.029%/cycle) than that of 1Me (0.047%/cycle) (Figure 2) owing to a bulkier substituent preventing from nucleophilic attack on the side chain of anthraquinone. Levich analyses show comparable diffusion coefficients for 1Et (4.55×10−6 cm2 s−1) and 1Me (3.26×10−
6 cm2 s−1). These results demonstrate that introducing a bulkier substituent is an effective strategy to improve solubility in water and cycle stability without degrading other physical properties (e.g., redox potential and diffusivity).
Reference
[1] R. G. Godon, M. J. Aziz, et al., ACS Energy Lett.
2023, 8, 600.

Figure 1