bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Electron Microscopy Investigation of Electrolyzer Degradation
Authors: Cullen David A. , Yu Haoran , Arregui-Mena David , Padgett Elliot , Alia Shaun M , Bender Guido , Komini Babu Siddharth , Mukundan Rangachary
Published: February 2024

Low-temperature proton exchange membrane water electrolyzers (PEMWEs) are a key technology for green hydrogen production from renewable energy sources. Developing efficient and durable components for the membrane electrode assembly (MEA) at the heart of the electrolyzer is critical for meeting DOE’s Hydrogen Shot target of $1 per kg of hydrogen by 2031. Of key interest to the efficiency and longevity of the electrolyzer is the anode-side of the MEA, where the costly iridium (Ir) catalyst is prone to dissolution at the high potentials and acidic conditions experienced in the cell. Further, the interfacial contact resistance between the catalyst and porous transport layer (PTL) plays a key role in electrolyzer performance and can degrade over time. Understanding and mitigating these degradation modes is critical for reducing the cost the PEMWEs and enabling commercialization.

Here we will present the results of electron microscopy characterization performed on degraded anode catalyst layers and coated PTLs. Cross sections of MEAs submitted to different cycling protocols (square wave, triangle wave, steady-state, etc.) were prepared by diamond-knife ultramicrotomy and studied with in the scanning transmission electron microscope (STEM). Using energy dispersive X-ray spectroscopy (EDS), the dissolution and migration of Ir into the membrane was tracked and correlated with performance losses. The impact of PTL contact area on inhomogeneous degradation in anodes with low catalyst loadings will also be presented. In addition, PTL coating thickness and uniformity will be correlated with interfacial contact resistance measurements using a combination of focused ion beam (FIB), scanning electron microscopy (SEM) and STEM-EDS.

Funding for this work was provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the H2NEW Consortium. Electron microscopy research conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
The Influence of Doping in the Electrocatalytic Properties of NiFe2O4-Derived Nitrides
Authors: Coca Clemente José Antonio , Retuerto Maria , Ocón Pilar , Rojas Sergio
Published: February 2024

Transition metal nitrides (TMNs) have been widely studied in the last years due to their extraordinary properties such as high electrical conductivity and versatile physical and chemical properties. They can be easily synthesize from metal oxide precursors and, in addition, they display electrocatalytic activities similar to Pt and other conventional noble metal electrocatalysts.1 Among them, several Ni-, Co- and Fe-based nitrides have been studied as electrocatalysts for the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).2–4 The combination of these metals in different proportions (stoichiometric and non-stoichiometric) can give place to a wide range of electrocatalysts with better electrochemical performance than the single metal nitrides. Apart from them, 2nd and 3rd row TMNs like Mo- and W-based nitrides can display high HER activity, surpassing those 1st row TMNs above-mentioned, therefore doping 1st row TMNs with Mo or W, even in very small amounts, can increase significantly the electrocatalytic performance of these materials.5

In this work, NiFe2O4-derived nitrides and their Mo- and W-doped versions were synthesized via the resorcinol-formaldehyde sol-gel polymerization method, followed by nitridation in ammonia atmosphere. The influence of doping for the HER, ORR and OER reactions in alkaline electrolyte has been studied. As observed, W-doping results in improved ORR and OER activities. Characterization techniques, such as XRD, TEM and XPS, are being performed in the initial and used catalysts, observing a structural change from the initial oxide (NiFe2O4) to the final nitride (NiFe2N), including the doped versions, which can help to understand their electrocatalytic properties.

References:

C. Das, N. Sinha, and P. Roy, Small, 18 (2022).

S. H. Gage, B. G. Trewyn, C. V. Ciobanu, S. Pylypenko, and R. M. Richards, Catal Sci Technol, 6, 4059–4076 (2016).

Y. Yang, R. Zeng, Y. Xiong, F. J. Disalvo, and H. D. Abruña, J Am Chem Soc, 141, 19241–19245 (2019).

T. Yamaguchi, M. Sakita, M. Nakamura, and T. Kobira, J Magn Magn Mater, 215–216, 529–531 (2000).

Z. Chen et al., Angewandte Chemie, 130, 5170–5174 (2018).

Figure 1
Efficient Alkaline Hydrogen Evolution Reaction Using Superaerophobic Ni Nanoarrays with Accelerated H2 Bubble Release
Authors: Kim Jaerim , Jung Sang-Mun , Kim Yong-Tae , Kim Jong Kyu
Published: February 2024

Water electrolysis for producing green hydrogen is of central importance in the hydrogen economy to meet the global mission of carbon neutrality. Hydrogen evolution reaction (HER) under alkaline conditions has many advantages in cost and stability over acidic HER, but it requires high overpotential due to sluggish reaction kinetics. Pt-based materials are still considered the benchmark for HER catalysts, however, their high cost is the major hurdle for large-scale applications, motivating tremendous efforts to find earth-abundant catalytic materials as alternatives.

In addition to catalytic materials, the formation and release of H2 bubbles on the surface of catalysts should be considered when designing efficient catalysts, as this significantly affects catalytic performance. Adhered H2 bubbles on the catalyst surface can cause reduced active surface sites, blockage of ion pathways, and destruction of catalyst film by inducing a large stretch force. Despite the adverse effects of H2 bubbles adhering to catalyst’s surface on the performance of water electrolysis, the mechanisms by which H2 bubbles are effectively released during the alkaline HER remain elusive.

In this study, we conducted a systematic investigation on the effect of nanoscale surface morphologies on H2 bubble release behaviors and HER performance by employing earth-abundant Ni catalysts consisting of an array of Ni nanorods (NRs) with controlled surface porosities. Both aerophobicity and hydrophilicity of the catalyst’s surface vary according to the surface porosity of catalysts. The Ni catalyst with the highest porosity of ~52% exhibits superaerophobic nature as well as the best HER performance among the Ni catalysts. It was found that the Ni catalyst’s superaerophobicity combined with the effective open pore channels enables the accelerated release of H2 bubbles from the surface, leading to a significant improvement in geometric activities, particularly at high current densities, as well as intrinsic activities including both specific and mass activities. It was also demonstrated that the superaerophobicity enabled by highly porous Ni NRs can be combined with Pt and Cr having optimal binding abilities to further optimize electrocatalytic performance. Our work can help to elucidate the fundamental and practical design rules for efficient alkaline HER catalysts consisting of earth-abundant elements.
(Digital Presentation) Metal Alloy Nanoparticles Dispersed in Amorphous Titanosilicate for Hydrogen Evolution Reaction Catalyst with Much Lower Overpotential Than That of Benchmark Catalyst in a Wide pH Range
Authors: Vemula Koteswararao
Published: February 2024

Different kinds of metallic nanoparticles (Pd, Pt, Au, Cu, Ag etc.) are widely used in Electrochemical, Optoelectronic and Photovoltaic applications to harvest sunlight in order to increase the efficiency of devices.

ETS-10, which is a synthetic microporous material consisting of –Ti-O-Ti-O-Ti- quantum wires running along [110] and [1-10] direction in polymorph B, has been of great interest in many applications like Electrochemical, Optoelectronic and Photovoltaic applications, due to its so unique (it contains periodically positioned quantum wires [-O-Ti(O-)4-O-] with a diameter (d) of ∼0.67 nm running along the two perpendicular directions in the crystal, tetrahedral framework structures and compostion, well defiend acidity, uniform pores, highly cation exchange selectivity, and good thermal stability are widely used as commercial catalysts, ion exchangers, and adsorbants) properties.

As a results, Tafel slop clearly indicated that performance was much better than pure Pt plate and the quite stable upto 72 hours at all pH conditions.

Figure 1
(Invited) High Performing Fuel Cell Stack and Systems
Authors: Bodén Andreas , Kylhammar Lisa , Dombrovskis Johanna , Göransson Gert
Published: February 2024

PowerCellGroup has worked in the field of fuel cell systems and fuel cell stacks for more than 25 years. The development of both systems and stacks have gone hand in hand and have been important to reach the targets for both.

The fuel cell stack currently offered to the market has been developed during the last 10 years. Starting out with focus on passenger vehicles to achieve the requirements on power density. The second step the development was tailored to meet the demands from heavy-duty usage, that requires high efficiency at high power output and longer durability as well as increased operating temperature. This second stage unlocked the usage of fuel cell in more applications like, stationary high-power generation, off-rad machinery and lately the aviation sector.

The later years the implementation of hydrogen and fuel cell on the market have accelerated and more commercial usage putting larger requirement on higher power, longer durability, higher operating temperatures etc. For example, how to install several MW into marine vessels.

The third phase that we are now entering is to take the fuel cell to the next level, to the sky. Improving power density towards 5-6 kW/kg, operating temperature up to 120°C, and larger stack sizes 300 kW scalable to about 1 MW this to meet the higher power demand by aircraft. PowerCell is on a good track in all these aspects to be ready for the future. In this talk will be about how we constantly improving and challenging the fuel cell system and fuel cell stacks to be used in commercial operation.
Rapid Manufacturing of Thin Films for Perovskite Solar Cells
Authors: Druffel Thad
Published: February 2024

The perovskite solar technology has shown impressive improvements in just over a decade with efficiencies rivalling traditional devices. However, much of this work is done using spin coating and long annealing times. In this work we demonstrate the deposition of several thin films (NiO, perovskite and SnO2) using a blade coating technique and annealed using an intense pulsed light technique. These processes allow for the complete deposition and post-process to be completed in just seconds, yielding quality devices at high manufacturing speeds. The talk will discuss the formulation of the individual inks, deposition and annealing. Results from I-V, UV-Vis, XRD and SEM will establish the working principals of the rapid manufacturing technique.
Kinetics of Charge Transfer at Carbon-Based Counter Electrodes for Dye-Sensitized Solar Cells with Aqueous Electrolytes
Authors: Holzhacker Daniel , Ringleb Andreas , Schlettwein Derck
Published: February 2024

Dye-sensitized solar cells (DSSCs) might provide a highly sustainable alternative for next generation photovoltaics. This is due to their low-energy production from abundant materials, short energy payback time, high efficiency under low illumination intensities (i.e., diffuse light or indoor conditions), and versatile concepts of applications. However, some commonly used electrolyte components are environmentally problematic. Acetonitrile or other volatile organic solvents, e.g., as well as carcinogenic cobalt complexes should not leak from DSSCs. Sealing foils, however, which are typically used to prevent such leakage, carry a risk of long-term failure.

Replacing the organic solvent by water offers several advantages, as it is environmentally benign, less volatile and the cell function, further, cannot be damaged by the intrusion of water vapor. Instead of Co-complexes, e.g., the stable organic radical TEMPO (2,2,6,6-tretramethylpiperidine-1-oxyl) can serve as an alternative redox mediator with a highly positive redox potential (0.71 V vs. NHE). Using TEMPO, power conversion efficiencies (PCE) of up to 4.3% and high open-circuit voltages (V
oc = 0.955 V) have been reported.[1] However, the use of TEMPO is limited by its solubility in water (C
max < 0.15 M). Its derivative 4-hydroxy-TEMPO (OH-TEMPO) possesses a significantly higher solubility in water (C
max > 2 M) and a more positive redox potential (0.81 V vs. NHE), making it a promising candidate as a redox mediator.

In this work, we built DSSCs with TEMPO and OH-TEMPO based aqueous electrolytes, Y123-sensitized TiO2 photoanodes, and counter electrodes coated with poly(3,4-ethylenedioxythiphene) (PEDOT). For OH-TEMPO, the short-circuit current density (j
sc) and open-circuit voltage were higher than with TEMPO, but the fill factor (FF) and the PCE were significantly lower. By impedance studies, large charge transfer resistances at the counter electrode (R
CE) were obtained for OH-TEMPO in combination with additives such as 1-methylbenzimidazole (MBI), indicating a strong kinetic limitation of the OH-TEMPO+ reduction. However, we found that such additives as MBI or other organic compounds, are necessary to suppress recombination at the photoanode/electrolyte interface. Thus, we subsequently studied different counter electrode materials, such as platinum (reference), conducting polymers, and carbon materials, in contact to OH-TEMPO electrolytes with MBI to determine R
CE and find suitable materials for the application in DSSCs.

[1] Yang, W., Söderberg, M., Eriksson, A. I. K. & Boschloo, G. Efficient aqueous dye-sensitized solar cell electrolytes based on a TEMPO/TEMPO+ redox couple. RSC Advances 5, 26706–26709 (2015).
Copper as an Alternative Metallization Scheme for Photovoltaics
Authors: Druffel Thad
Published: February 2024

Copper is an ideal replacement for silver in metallization of solar cells as it is 97% the conductivity but 1/100ththe cost. As the industry strives to scale production to a multi-terawatt scale, there simply is not enough silver to meet the industry need. In this talk, the replacement of silver with copper will be reviewed for a number of device architectures that are already commercial and ones that are nearing commercialization. The work will describe what the issues that need to be addressed and how the community can provide results. Examples of copper as a metallization will also be supplied.
Heterostructure Design of Anode Materials for High-Performance Sodium-Ion Batteries
Authors: Lim Hyojun , Kim Sang-Ok
Published: February 2024

The growing global demand for carbon neutrality has led to an increase in the use of electric vehicles and large-scale energy storage systems, which rely heavily on lithium-ion batteries. However, there are concerns about the limited availability of lithium resources, which may result in depletion and price increases in the near future. To solve this issue, researchers are actively exploring alternative next-generation secondary battery systems to replace current lithium-ion batteries. Sodium-ion batteries have received significant attention as one of promising candidates, as sodium is abundant in the earth's crust and economically viable compared to lithium.

Although hard carbon has been considered a reversible anode material capable of sodium-ion insertion and extraction, high-capacity anode materials are required to increase the energy density of sodium-ion batteries. Among various candidates, conversion- and alloy-based materials are highly regarded due to their high theoretical capacity. However, challenges such as huge volume changes of active materials, sluggish reaction rates, and interfacial instability that occur during charging and discharging need to be overcome for these materials to be applied in high-performance sodium-ion batteries.

To address these challenges, herein, we designed heterostructured anodes with a unique structure by combining conversion- or alloy-based materials with a porous silicon oxycarbide (SiOC) nanocoating layer, which possesses high surface capacitive reactivity and mechanical strength. We controlled the dispersion of the precursors in silicon oil and performed heat treatment to synthesize high-capacity heterostructured composites (MoS2@SiOC and Sn@SiOC). Subsequently, we conducted extensive physicochemical and electrochemical characterization as well as post-mortem analysis to investigate the properties of these composites, with a specific focus on the impact of the heterostructure on their battery performance. We anticipate that this heterostructure approach will pave the way for the development of novel, high-performance anode materials for sodium-ion batteries in the future.
Rationally Designed in-Situ Gelled Polymer-Ceramic Hybrid Electrolyte Enables Superior Performance and Stability in Quasi-Solid-State Lithium-Sulfur Batteries
Authors: Shah Vaidik , Joo Yong Lak
Published: February 2024

Despite boasting giant leaps in performance improvement over the years, the current commercial standard, Li-ion batteries, are fast approaching their theoretical limits. Meanwhile, Lithium-Sulfur (Li-S) batteries offering ultra-high theoretical energy density (～2600 Whkg-1), cost-effectiveness, and nontoxicity are being seen as promising alternatives. Despite their plentiful advantages, the practicality of Li-S batteries has been largely stymied by several challenges: a) deleterious polysulfide dissolution and ‘shuttle effect’, b) significant volume change of S cathodes during cycling, c) safety concerns with flammable traditional glyme-based electrolyte, and d) the instability of Li anode. To mitigate these challenges, researchers have explored all-solid-state electrolytes, but their poor Li-ion conductivity, high interfacial impedance, and need for expensive, exotic materials and complex fabrication procedures severely limit their practical application.

To overcome these challenges, we propose an in-situ gelled polymer-ceramic hybrid silsesquioxane-based electrolyte system. The gelled matrix, thermally crosslinked post cell fabrication, immobilizes the glyme-based liquid electrolyte and exhibits high liquid-like ionic conductivities (1.03 mS.cm-1), low interfacial impedance, and high oxidative potential (>4.5V vs. Li/Li+) . In this study, in addition to vastly decreased flammability, we report superior Li-ion conductivity compared to state-of-art solid-state Li-S electrolytes. This high ionic conductivity translated to a significantly improved specific capacity of 1050 mAh.gS-1 at 0.2 C, elevated Coulombic efficiencies (>98.5%), and elevated rate kinetics. The gelled electrolytes exhibited stable cycling in a large temperature range (-10oC - 60 oC). Moreover, polysulfide permeation studies and subsequent DFT calculations revealed that the gelled electrolyte exhibited strong chemical absorptivity to lithium polysulfides due to the polar silsesquioxane core, which translated to superior capacity retention (>80% over 200 cycles). Further, post- mortem XPS characterization studies revealed the formation of stable SEI at the anode and cathode, and SEM of cycled anodes showed reduced dendritic formations. Finally, the electrolyte was tested in practical pouch cell architecture, and the cells demonstrated excellent reliability even under mechanical stress. This work successfully reports a robust, rationally designed gelled electrolyte system for developing safe and high-performance quasi-solid state Li-S batteries.
Investigating the Effects of Modified Interlayer Spacing within Mixed Metal Oxide Cathode Materials for Next-Generation Aqueous Rechargeable Zinc-Ion Batteries
Authors: Gourley Storm William D , Miliante Caio Miranda , Ibarra Espinoza Alejandra , Baker Thomas James , Rubel Oleg , Adams Brian D , Higgins Drew Higgins
Published: February 2024

Aqueous rechargeable zinc-ion batteries (ZIBs) are a promising addition to the current energy storage landscape, particularly supporting the decarbonization of the power sector as a low-cost, high safety alternative to lithium-ion batteries. Unfortunately, the relative infancy of ZIBs means that there are a limited number of reported cathode materials, and a divisive understanding of the operating principles for those which have been reported including Mn- and V-oxides. The large solvation shell of the working cation (Zn2+) imparts several design requirements for cathode material development, specifically the need for sufficient void space for Zn2+ intercalation, further limiting the materials which have been reported. Looking to other well-established battery chemistries, we considered the use of layered mixed metal oxides (MMOs) with Mn due to its known electrochemical activity within the operating voltage of aqueous ZIBs. We developed several MMO cathodes with tuned interlayer distance to achieve the larger void spacing capable of accommodating Zn2+. We investigated the impact of composition on the structural and electrochemical properties of 15+ different MMO materials. We determined that interlayer spacing plays critical role in electrochemical performance and that there is an optimal composition to provide enhanced specific capacity to the battery. Considering the narrow range of reported ZIBs cathodes, in this study we proposed several new materials that expand the scope of viable cathodes for next generation ZIBs and provides direction for future researchers to accelerate new material development for this technology.
Chimie Douce Derived K-Based P2-Type Transition Metal(s) Layered Oxides for Secondary K-Ion Batteries
Authors: Jha PawanKumar Kumar , Barman Pubali , Abakumov Artem M. , Fichtner Maximilian , Barpanda Prabeer
Published: February 2024

Owing to great societal and technological benefits, there has been a remarkable growth in the industrial demand for enhanced energy storage for many target applications including electric vehicles, aerospace applications, and portable electronics. Secondary K-ion batteries (KIBs) are among the potentially inexpensive candidates for energy storage systems beyond state-of-the-art Li-ion batteries (LIBs). Electrochemical cells based on mobile carrier K+ can provide efficient energy storage because of comparative ionic diffusion in bulk and swift charge transfer at the interface due to weak Lewis’s acidity.1,2 Despite various advantages over LIBs and NIBs, the roadblock of practical KIB implementation lies in identifying suitable cathodes that reversibly (de)intercalate K+ at optimum voltage, swift rate, and with prolonged cycle life.

Despite constant efforts to develop new cathodes for K+ -ion batteries, several challenges such as low concentrations of K-ions due to strong electrostatic repulsions between the K+ - K+ ions and difficulty in preparation from direct synthesis routes3 limit its practical application. In this scenario, we have adopted the chimie douce (soft chemistry) method to design the novel layered transition metal oxide cathode from the parent P2 type Na-based system. In addition, we have probed the ion exchange mechanism using X-ray diffraction and transmission electron microscopy (TEM) techniques. Rietveld analysis confirmed the structure having a P2-type stacking sequence with hexagonal symmetry and P6/3mmc space group. Further, we have successfully examined the chemical ion-exchanged novel layered P2- K2/3Co1/3Mn2/3O2 as a cathode for KIB at ambient and high temperatures. It delivered a good capacity (~70 mAh/g) with an average redox potential of 3.0 V along with good cycling stability and coulombic efficiency (CE) in temperature ranging from 25-50 ºC. Ex-situ X-ray diffraction analysis and potentio/galvanostatic titration techniques were used to analyse the K+ insertion mechanism. This study can assist in developing new insertion K+ host materials for viable and reliable practical applications.

References:

Zhang et al., Small,
2020, 16, 2002700.

T Hosaka et al., Rev., 2020, 120, 6358-6466.

J . H. Jo et al., Adv. Energy Mater.
2020, 10, 1903605
(Invited) A Dive into the Complex Mechanisms That May or May Not Increase Li/Na Mobility in Solid State Conductors
Authors: Ceder Gerbrand
Published: February 2024

The conductivity of Li and Na has achieved remarkably high values in some materials, higher than what has been achieved in liquid electrolytes. Because there is no mobile solvation shell in solid-state conductors, the maximum of conductivity is essentially unlimited. I will discuss our current understanding of the compositional and structural elements that contribute to very high alkali ion mobility. This will include a discussion, of activated complexes that create concerted motion, possible high-entropy effects, the effect of (poly)anions, and structural topology.
Interfacial Chemical Stability of Doped Li7-XLa3Zr2
-X(Nb/TaX)O12 with LiCoO2 Electrode Material
Authors: Pateli Ioanna Maria , Vestli Mihkel , Irvine John
Published: February 2024

Garnet-type oxide solid state electrolytes (SEs) are promising candidates due to their potential high ionic conductivity and chemical stability with Li for the replacement of flammable liquid electrolytes used in the current Li-ion batteries. Intense research has been focused on optimising the interface of garnets with Li, with the positive side to be somehow neglected. A significant issue of oxide SEs, hurdling their industrial application, is their poor contact with positive materials due to their rigidity. Poor interfacial contact leads to the need of co-sintering at high temperatures (> 400 °C), which enables side reactions and unwanted processes like cation intermixing, diffusion of elements and formation of non-conductive secondary mixed phases.

In this work the chemical stability of Ta and Nb doped LLZO garnet SE was tested in contact with LiCoO2, a common positive material used in the battery industry. Initially, mixed powders of SE and active material were heat treated and studied using Raman spectroscopy and scanning electron microscopy to observe side reactions. In order to improve contact between the two materials, instead of already synthesized crystalline powder, nitrate precursors were also used for in-situ synthesis of LiCoO2 material in contact with the garnet. Mixtures of the SE powder and nitrate precursors for LiCoO2 were also heat-treated at various temperatures for different time periods in different gas atmospheres. The heat-treated materials were then analysed extensively using scanning electron microscopy coupled with energy dispersive X-Ray element mapping and with Raman microscopy to prove the existence or absence of secondary mixed phases at given conditions. Additionally, the optimized heat-treatment conditions were adapted for layered garnet SE/LiCoO2 samples to study the actual electrolyte/electrode interface at the same conditions used for powder mixtures. Based on the results the symmetrical LiCoO2/garnet SE/LiCoO2 cells will be prepared and tested electrochemically.
CO2-Assisted Li–O2 Batteries: Challenges and Strategies Towards Practicality
Authors: Marques Mota Filipe
Published: February 2024

Today, safe alternatives to lithium–ion batteries able to answer ever-increasing energy demands require an urgent focus. Amongst promising candidates, the environmentally-friendly conversion-type lithium–oxygen (Li–O2) battery offers high theoretical energy density by coupling a Li metal anode with an “air-breathing” cathode. Since its inception, however, the Li–O2 cell has remained plagued by the poor safety characteristics of the metal anode and the sluggish O2 electrochemistry at the cathode side, leading to poor round-trip efficiencies and unpractical lifetimes. Most critically, efforts to shift from pure O2 to practical ambient air conditions have long revealed that CO2 and moisture in the air radically affect the O2 electrochemistry, the resulting product selectivity, and the overall performance of these devices. In a tetraglyme-based electrolyte, our team demonstrated that CO2 shifts the discharge reaction mechanism toward the formation of Li2CO3 (with complete Li2O2 absence), which requires unpractical potentials (>4.5 V) upon cell recharge. In this talk, efforts to shed light on the mechanism of these devices and uncover strategies for performance enhancement will be discussed. We recently probed the possibility of tuning the battery cycling conditions/operating temperatures and the solvation properties of chosen solvents/salts as promising strategies to stabilize soluble peroxocarbonate reaction intermediates with lower oxidation potentials. Alternatively, our team has also shed light on the promise of integrating suitable redox mediators to facilitate the decomposition of Li2CO3 in this CO2-assisted Li–O2. A correlation between the required concentration of redox species and the morphology/crystallinity of discharge products and the promise of coupling for the first time electrochemical/spectroscopic analyses to uncover the nature of these operating redox species (e.g., Br2···Br3
− anionic complexes) will be further discussed during this talk.
The Mg Electrode Cycling Mechanism in Simple Salt Glyme Electrolytes
Authors: Sankowski Andrzej , Dimogiannis Konstantinios , Holc Conrad , Parmenter Christopher , Newton Graham , Walsh Darren , O'Shea James , Khlobystov Andrei , Johnson Lee
Published: February 2024

The lithium-ion battery (LIB) has been at the forefront of innovations in energy storage since its commercialisation over 30 years ago. As we reach the practical specific capacity limit of current state-of-the-art materials, novel and innovative battery technologies are required to satiate the requirements of energy intensive applications such as electric vehicles.
1
The use of a lithium metal negative electrode has been proposed to increase the energy density, however the high reactivity causes poor cycling performance due to electrolyte degradation, dendrite formation and safety issues.
2
The magnesium electrode offers a solution that has double the theoretical volumetric capacity of the lithium electrode while simultaneously mitigating dendritic growth, reducing raw material costs and greatly increasing sustainability.
3,4
Previous work has shown that traditional LIB electrolytes are not compatible with magnesium metal, and the plating and stripping mechanism that underpins how magnesium electrodes cycle is poorly understood.
5

Here we explored the mechanism of magnesium plating and stripping in glyme-based electrolytes with a range of additional additives. We show that in the pure electrolyte solution, interphase formation is critical to stable cycling but that this is accompanied by significant degradation and accumulation of inactive Mg.6 We establish the three-dimensional chemical composition of Mg deposits in the different electrolyte formulations using a combination of focused ion beam-scanning electron microscopy (FIB-SEM), energy dispersive x-ray spectroscopy (EDX) and transmission electron microscopy (TEM). We use these findings to develop a mechanistic understanding that explains the electrochemical cycling performance of magnesium metal negative electrodes. In situ electrochemical quartz crystal microbalance (EQCM) measurements are used to evaluate the plating and stripping efficiency of the electrodes and to identify non-electrochemical degradation reactions between Mg and the electrolyte solutions.

References:

1 R. Shah, V. Mittal, E. Matsil and A. Rosenkranz, Adv. Mech. Eng., 2021, 13, 1–9.

2 Z. Hu, J. Li, X. Zhang and Y. Zhu, Front. Chem., 2020, 8, 409.

3 M. Fichtner, Magnesium Batteries: Research and Applications, Royal Society of Chemistry, 2019, vol. 2020.

4 R. Attias, M. Salama, B. Hirsch, Y. Goffer and D. Aurbach, Joule, 2019, 3, 27–52.

5 S. B. Son, T. Gao, S. P. Harvey, K. X. Steirer, A. Stokes, A. Norman, C. Wang, A. Cresce, K. Xu and C. Ban, Nat. Chem., 2018, 10, 532–539.

6 C. Holc, K. Dimogiannis, E. Hopkinson and L. R. Johnson, ACS Appl. Mater. Interfaces, 2021, 13, 29708–29713.
Fatal Impurity for Electrochemical Mg Deposition/Dissolution
Authors: Mandai Toshihiko
Published: February 2024

Rechargeable magnesium batteries (RMBs) are promising large-scale stationary energy storage devices. A manufacturing system similar to that used for lithium-ion batteries should be adoptable to the fabrication of RMBs. However, the compatibility of RMB components with atmospheric components other than moisture has not been studied yet. This might be due to the uncertain preconception and misunderstanding of the passivation characteristics of magnesium. In this study, we investigated the effects of atmospheric conditions on the electrochemical dissolution–deposition behavior of magnesium in non-aqueous electrolytes.1

The compatibility of magnesium metal and electrolytes incorporating air-stable weakly-coordinated anions [B(HFIP)4]− or [Al(HFIP)4]− (HFIP: hexafluoro-iso-propoxyl) with dry air was investigated. The results of a simple cyclic voltammetry (CV) clearly demonstrate the far excessive care of magnesium metals against atmospheric O2, because reversible magnesium deposition/dissolution is possible using magnesium metals polished under dry air. However, cells assembled under a dry-air atmosphere show no features of electrochemical magnesium deposition/dissolution. To identify which component of a dry air has a significant detrimental effect on the electrochemical characteristics, systematic CV and open-circuit potential (OCP) measurements were conducted under certain atmospheric conditions with Ar, N2, and O2 and an air-tight voltammetry cell equipped with gas-inlet lines. The platinum and magnesium working electrodes show characteristic responses dependent on the inlet gases, and O2 gas is found to be detrimental for the electrochemical activities of magnesium (Figure 1). The time-profile of OCP and that of O2 content in the electrolyte under steady flow of O2 gas are correlated well, suggesting passivation of magnesium metal upon uptake of O2 in the electrolyte. The electrochemical impedance spectra of symmetric magnesium metal cells using oxygenated and deoxygenated electrolytes and X-ray photoelectron spectra further corroborate inactivation of magnesium by even miniscule amount, ca., 10 ppm, of O2 impurity.

Acknowledgement

This work was financially supported by the Advanced Low-Carbon Technology-Specially Promoted Research for Innovative Next Generation Batteries Program (ALCA-SPRING, Grant Number JPMJAL1301), NEXT Center of Innovation Program (COI-NEXT, Grant Number JPMJPF2016) of the Japan Science and Technology Agency, and KAKENHI (Grant No. 21K05263) of the Japan Society for the Promotion of Science.

Reference

T. Mandai and M. Watanabe, under revision.

Figure 1
(Invited) Low-Temperature Electrolytes for G/NMC811 Cells
Authors: Wang Chunsheng , Xu Jijian
Published: February 2024

We report and validate an electrolyte design strategy based on a group of soft solvents that strikes a balance between weak Li+–solvent interactions, sufficient salt dissociation and desired electrochemistry to fulfill all the aforementioned requirements. Remarkably, the 4.5-volt NMC811||graphite coin cells with areal capacities of more than 2.5 milliampere hours per square centimeter retain 75 percent (54 percent) of their room-temperature capacity when these cells are charged and discharged at −50 degrees Celsius (−60 degrees Celsius) at a C rate of 0.1C, and the NMC811||graphite pouch cells with lean electrolyte (2.5 grams per ampere hour) achieve stable cycling with an average Coulombic efficiency of more than 99.9 percent at −30 degrees Celsius. The comprehensive analysis further reveals an impedance matching between the NMC811 cathode and the graphite anode owing to the formation of similar lithium-fluoride-rich interphases, thus effectively avoiding lithium plating at low temperatures. This electrolyte design principle can be extended to other alkali-metal-ion batteries operating under extreme conditions.
Highly Concentrated Electrolytes for Lithium Sulfur Batteries – the Role of the Anion(s)
Authors: Kottarathil Aginmariya , Marczewski Maciej , Johansson Patrik , Wieczorek Wladyslaw
Published: February 2024

Lithium-sulfur batteries (Li-S) have attracted a lot of attention as a alternative/complement to lithium-ion batteries (LIBs) – due to both high energy density, availability, and inexpensive materials used.[1]

Yet, dissolution of sulfur from the C/S cathode and subsequent shuttling of lithium polysulfides (LiPS) to the anode as well as the instability of the Li metal anode itself are true scientific and technological challenges. Advancing in the field of electrolytes is one promising way to overcome both issues.

Switching from the standard 1 M electrolyte design of LIBs to highly concentrated electrolytes (HCEs) may both prevent the dissolution of LiPSs and hinder dendrite formation at the lithium metal anode.[2]

Here we combine experimental methods and computational approaches to investigate several HCEs based on various Li-salts in several standard organic solvents. Experimentally we targeted electrochemical properties, local electrolyte structure, and physico-chemical properties, with focus on the role(s) of the Li-salt anions. Furthermore, to predict the solubility of sulfur the conductor like screening model for real solvents (COSMO-RS), a computational fluid phase thermodynamic approach, was used.[3] Overall, the challenges and opportunities associated with the use of HCEs in Li-S batteries will be addressed, also highlighting potential areas for future research and development.

References

Peng et al., "Drastic effect of salt concentration in ionic liquid on performance of lithium sulfur battery." Journal of the Electrochemical Society 169.5 (2022): 050515.

Suo et al., "A new class of solvent-in-salt electrolyte for high-energy rechargeable metallic lithium batteries." Nature communications 4.1 (2013): 1481.

Jeschke and P. Johansson, "Predicting the Solubility of Sulfur: A COSMO‐RS‐Based Approach to Investigate Electrolytes for Li–S Batteries." Chemistry–A European Journal 23.38 (2017): 9130-9136.
Safe Solvent-in-Salt Electrolytes for Dendrite-Free Zinc Metal Batteries
Authors: Jeong Minji , Lim Jaehong , Oh Si Hyoung
Published: February 2024

As global markets for electric vehicles (EV) and energy storage systems (ESS) expand rapidly, there are growing needs to develop alternative battery systems to replace current lithium-ion battery (LIBs) technology, which suffers from high material cost, and insufficient safety. Rechargeable zinc batteries have emerged as one of the most viable and sustainable candidates to replace LIB owing to various beneficial features of zinc such as natural abundance, easy recyclability (by electrowinning), high safety and high volumetric capacity (5,854 Ah/L) compared with lithium (2,062 Ah/L). However, parasitic side reactions such as spontaneous Zn corrosion & hydrogen evolution, and unregulated dendritic growth of Zn deposit may occur in the aqueous electrolytes, which may eventually degrade the battery performance and safety seriously. In this work, we focus on an alternative method for regulating the morphological development of the Zn metal deposit using highly-concentrated organic electrolytes, which exhibits particular physicochemical properties such as high electrochemical window, high stability, and non-flammability. We will show that it does not only suppress the formation of dendrite effectively during Zn plating-stripping process via regulating the crystal growth of Zn deposits, but also hold a flame-retarding property, thereby making it appropriate as a highly-safe anode for rechargeable batteries. This study proposed a new strategy of making a battery with dendrite-free operation, high stability, and a long cycle-life by controlling the crystal facet of a Zn metal deposit using highly-concentrated organic electrolytes.

Keywords: Zinc metal, highly-concentrated organic electrolytes, dendrite-free, high redox stability

Acknowledgments

This work was supported by the KIST institutional program (KIST-2E32582) and the National Research Foundation of Korea (NRF-2021R1A2C2008680)
A New Approach in Surface Modification of Manganese Based Cathode Materials for Enhanced Performance in Zinc Aqueous Batteries
Authors: Zhanadilov Orynbay , Kim Hee Jae , Myung Seung-Taek
Published: February 2024

With the growing demand for sustainable and environmentally friendly energy storage solutions, zinc-aqueous batteries have emerged as promising alternatives to conventional lithium-ion batteries. Among the various cathode materials studied for zinc-aqueous batteries, manganese dioxide (MnO2) has garnered significant attention due to its high theoretical capacity, abundance, and non-toxic nature. However, the intrinsic limitations of MnO2, including low electrical conductivity and sluggish kinetics, have hindered its practical application. To address the aforementioned limitations, we present a new approach in surface modification of KxMnO2 cathode with improved electrochemical performance for zinc-aqueous batteries.

In this study, the KxMnO2 cathode material’s surface has been fluorinated, that enhances capacity retention of the material and effectively improves the overall electrochemical performance. Structural and morphological characterizations of the surface modified KxMnO2 were performed using operando X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), X-ray Absorption Near Edge Spectroscopy (XANES) and thermogravimetric analysis (TGA). Furthermore, X-ray photoelectron spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) confirmed the successful fluorination of the material surface.

Electrochemical tests, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), were conducted to evaluate the performance of the surface fluorinated KxMnO2 cathode in comparison to pristine KxMnO2. The results demonstrated a remarkable improvement in the specific capacity, rate capability, and cycling stability of the modified cathode. The improvement of electrochemical performance can be attributed to the effect of the fluorine element, which alleviates the structural degradation of KxMnO2 during cycling. The improved electrochemical performance of the KxMnO2 cathode paves the way for the development of high-performance, cost-effective, and environmentally friendly zinc-aqueous batteries.
(Invited) Mixed Conduction in Ceramic Electrolytes For Intermediate-Temperature Fuel Cells and Electrolyzers
Authors: Kee Robert J. , Zhu Huayang , Ricote Sandrine , Jackson Greg
Published: February 2024

High-temperature fuel cells and electrolyzers (e.g., T > 700 ˚C) rely on oxide electrolytes such as stabilized cubic zirconia that conduct a single defect, oxygen vacancies. Intermediate-temperature electrochemical cells (e.g., T < 650 ˚C) utilize mixed conducting ceramic electrolytes, that conduct multiple defects. Operating at T < 600 ˚C facilitates lower-cost interconnect materials and balance-of-plant components, but the mixed conductor behavior can reduce fuel cell voltages and lower electrolyzer faradaic efficiencies. Predicting behavior of these mixed conductors, even at open-circuit voltage, requires modeling the coupled transport of the multiple conducting defects in the electrolyte. Detailed models of mixed conductors coupled to porous electrode models can simulate cell performance over a broad range of operating conditions. This presentation highlights models of two types of cells with mixed conducting oxide electrolytes. Firstly, gadolinium-doped ceria (GDC) primarily conducts oxygen vacancies but also some electrons via a reduced-ceria small polaron, but it performs well in intermediate temperature solid-oxide fuel cells [1]. Secondly, yttrium-doped barium zirconates (BZY) primarily conducts protons but also oxygen vacancies and small polarons, which contribute to electronic leakage. Variants of BZY electrolytes perform well in fuel cells and electrolyzers [2-4]. This paper focuses on cell-level models of these mixed-conductors and how to identify favorable regions for high performance in fuel cells and electrolyzers.

Zhu, A. Ashar, R.J. Kee, R.J. Braun, G.S. Jackson, “Physics-based model to represent the membrane-electrode assemblies of solid-oxide fuel cells based on gadolinium-doped ceria,” J. Electrochem. Soc., Under revision, 2023.

J. Kee, S. Ricote, H. Zhu, R.J. Braun, G. Carins, J.E. Persky, “Perspectives on technical challenges and scaling considerations for tubular protonic-ceramic electrolysis cells and stacks ,” J. Electrochem. Soc. 169:054525 (2022).

Zhu, Y. Shin, S. Ricote, R.J. Kee, “Defect incorporation and transport in dense BaZr0.8Y0.2O3-d membranes and their impact on hydrogen separation and compression,” J. Electrochem. Soc., Under revision, 2023.

Zhu, S. Ricote, R.J. Kee, “Thermodynamics, transport, and electrochemistry in proton-conducting ceramic electrolysis cells,” in High Temperature Electrolysis, W. Sitte and R. Merkle, Editors, IOP Publishing, 2023.
(Invited) Optically and Chemically Modulated Oxygen Transport across Interfaces
Authors: Seo Han Gil , Defferriere Thomas , Tuller Harry L.
Published: February 2024

Materials that conduct oxygen are central to many technologies that promise more highly efficient chemical to electrical and electrical to chemical energy conversion, as exemplified by solid oxide fuel and electrolysis cells (SOFC/SOEC), permeation membranes for partial oxidation of hydrocarbons and solar thermal driven chemical conversions. We begin by describing recent insights achieved in controlling the oxygen reduction reaction (ORR) on mixed ionic electronic conductors (MIEC). We have been able to demonstrate the ability to reversibly depress or enhance the oxygen exchange reaction at MIEC surfaces by orders of magnitude by infiltrating the surfaces with binary oxides with controlled acidity. This we demonstrate can be correlated with the ability of the surface additives to deplete or accumulate electrons needed for the ORR. With these insights, we have been able to understand more fundamentally the source of chromia-induced poisoning of SOFC cathodes and the means to recover performance following poisoning. We next turn our attention to the well known blocking of oxygen ions at grain boundaries in solid oxide electrolytes where grain boundary resistances can drop the overall oxygen ion conductance in polycrystalline solid electrolytes by orders of magnitude. The barriers to oxygen transport across grain boundaries are largely attributed to space charge barriers that form at the grain boundary due to the positive core charge of the grain boundaries. We have demonstrated the ability to modulate the barrier potentials by illumination with above band gap light, illustrating the ability to enhance ionic conduction in solid electrolytes at reduced temperatures, while at the same time demonstrating a novel method for interrogating the distribution of barrier heights at grain boundaries and the dynamics associated with the resultant redistribution of oxygen vacancies in space charge regions under conditions of photo-induced electron-hole generation and recombination. This phenomenum is yet another example of the rapidly developing field of opto-ionics.