bluuebunny/crossref_metadata_2025 huggingface dataset:
Pinnwall: Heterogeneous Electrode Models from Integrating Machine Learning and Atomistic Simulation
Authors: Knijff Lisanne , Dufils Thomas , Shao Yunqi , Zhang Chao
Published: February 2024

Electrochemical energy storage always involves the capacitive process. The prevailing electrode model used to study such polarizable electrode-electrolyte systems is the Siepmann-Sprik model, which has been recently extended to study the metallicity in the electrode model by including the Thomas-Fermi screening length. Nevertheless, a further extension to heterogeneous electrode models is required. Here, we address this challenge by integrating the atomistic machine learning code (PiNN) [1] for generating the base charge [2] and response kernel [3] and the classical molecular dynamics code (MetalWalls). This leads to the development of the PiNNwall [4] interface. Apart from the cases of chemically doped graphene and graphene oxide electrodes as shown in this study, the PiNNwall interface also allows us to probe polarized oxide surfaces in which both the proton charge and the electronic charge can coexist. Therefore, this work opens the door for modelling heterogeneous and complex electrode materials often found in energy storage systems.

[1] Shao, Y.; Hellström, M.; Mitev, P. D.; Knijff, L.; Zhang, C. PiNN: A python library for building atomic neural networks of molecules and materials. J. Chem. Inf. Model.
2020, 60, 1184.

[2] Knijff, L.; Zhang, C. Machine learning inference of molecular dipole moment in liquid water. Mach. Learn.: Sci. Technol.
2021, 2, 03LT03.

[3] Shao, Y.; Andersson, L.; Knijff, L.; Zhang, C. Finite-field coupling via learning the charge response kernel. Electron. Struct.
2022, 4, 014012.

[4] Dufils, T., Knijff, L., Shao, Y. and Zhang, C. PiNNwall: heterogeneous electrode models from integrating machine learning and atomistic simulation. arXiv preprint arXiv:2303.15307. 2023.

*This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (Grant Agreement No. 949012). We also acknowledge the support from the Centre for Interdisciplinary Mathematics (CIM) and the AI4Research initiative at Uppsala University.
Effect of Applied Stress on the Interfacial Kinetics, Ionic Conductivity, and Other Phenomena in Thin-Film Solid-State Batteries
Authors: Bhargava Bhuvsmita , Theodoru Stefan , Crofton Lane , Kozen Alexander C , Warecki Zoey , Stewart David Murdock , Song Yueming , Rubloff Gary , Albertus Paul
Published: February 2024

Controlled stress is critical to both fabrication and operation of solid-state batteries to ensure pristine, low-impedance interfaces. The effects of externally applied stresses on overall cell performance and degradation due to altered thermodynamics, interfacial kinetics, and bulk transport of the active species have been studied in several prior works. In addition to the applied stack pressure which can vary up to 100s MPa, internal and localized stresses up to a few ~1 GPa can be generated from volume changes during charge and discharge. Electrode volume changes can result in cracking and delamination, causing loss of conductive pathways and active electrode-electrolyte area, and electrolyte fracture in the case of dendrite growth. The extent of these stress-electrochemistry couplings depends on the material and geometry of interfaces that affects the local stress distribution. To decouple some of these stress-potential, stress-kinetics, and stress-transport coupling phenomena, we use a nanoindenter platform to apply controlled uniaxial compressive forces to a thin-film electrochemical devices and batteries1. Interfaces in a thin-film sample can be uniform and planar over large areas, helping us study the effect of stress on the interfacial electrochemistry more directly and with greater quantitative accuracy. In this work we present our observations and analysis on the direct electrochemical-mechanical coupling in thin-film TiO2 and V2O5 metal oxide thin films as the working electrode with the single-ion Li+ conductor solid electrolyte LiPON. Preliminary results show that external uniaxial compressive load affects the electrochemistry observed through cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements on thin-film batteries with TiO2 and V2O5 electrodes.

References:

(1) Song, Y.; Bhargava, B.; Stewart, D. M.; Talin, A. A.; Rubloff, G. W.; Albertus, P. Electrochemical-Mechanical Coupling Measurements. Joule
2023, S2542435123001137. https://doi.org/10.1016/j.joule.2023.03.001.
(Invited) Computing the Newns-Anderson Chemisorption Function from First Principles
Authors: Oberhofer Harald
Published: February 2024

In analysing the interactions of adsorbates with extended surfaces, theory, and to a large degree also experiments, tend to rely on adsorption models such as the famous Newns-Anderson model. There, the interaction of adsorbate and substrate is represented by the interaction of the adsorbate's one-electron frontier orbitals with the delocalised Bloch states of the substrate. Together with its simplified cousin, the d-band model, such adsorption models yielded significant insight into the chemistry of extended surfaces.

The Newns-Anderson Model gives rise to a so-called chemisorption function, a density of states weighted by the electronic coupling between adsorbate and substrate states, measuring the line broadening of an adsorbate frontier state upon adsorption. In my contribution, I will describe our efforts to compute the chemisorption function from first principles, employing a diabatization scheme to estimate electronic couplings between states. Recognizing the periodic nature of the substrate and the finite extent of computational supercells, we extend the original chemisorption function by a Brillouin zone integration to account for the (generally localized) adsorbate states' coupling to different substrate states at different points in reciprocal space. Including this integration, the chemisorption function not only converges well with both lateral simulation cell size and slab depth, but also compares well with experiments. We test our approach against highly accurate experimental measurements of ultrafast charge transfer of a probe Ar atom on various metal surfaces and find that the chemisorption function reproduces both absolute transfer rates and rate asymmetries due to spin on magnetic surfaces. Next to its predictiveness, though, the Newns Anderson chemisorption function allows us to investigate the charge transfer mechanism in terms of e.g. contributions of states with different angular momentum character, showing the importance of phase cancellation effects in interpreting charge transfer at surfaces.
Tailoring Breathing Behaviour of Solid Electrolyte Interphases (SEIs) Unraveled by Cryo-TEM
Authors: Guo Xuyun , DU Xiaoqiong , Nicolosi Valeria , Zhang Biao , Zhu Ye
Published: February 2024

The cycling stability of batteries is closely related to the dynamic evolution of solid electrolyte interphases (SEIs) in response to the discharging/charging processes. Here we utilize the state-of-the-art cryogenic transmission electron microscopy (cryo-TEM) and spectroscopy to probe the SEI breathing behaviour induced by discharging/charging on the conversion-type anode made of Fe2O3 quasi-cubes. The incorporation of the identical-location strategy allows us to track the evolution of same SEIs at different charge states, which unequivocally unravels SEI breathing featured by swelling (contracting) upon lithiation (de-lithiation), and the associated compositional change. Bare Fe2O3 anode develops an unstable SEI layer due to the intermixing with the lithiation product Li2O, which exhibits a large thickness variation upon breathing as well as excessive growth, causing substantial capacity fading within 100 cycles. A transition from organic to inorganic-type SEI is also identified upon cycling, which gives rise to significantly increased SEI resistance. To tailor the SEI behaviour, we apply N-doped carbon coating on Fe2O3 (Fe2O3@CN), which can effectively separate the lithiation product from SEI. A thinner and chemically more stable SEI layer develops on Fe2O3@CN, resulting in remarkably enhanced cycling stability compared to bare Fe2O3. Our work demonstrates the importance of understanding and optimizing the dynamic behaviour of SEIs to achieve better battery performance.
How Relevant Are SEI Studies from Half Cell Samples to Understand Aging Mechanisms in Potassium Batteries? An in-Depth Photoelectron Spectroscopy Study
Authors: Panasenko Iurii , Wildersinn Leonie , Jeschull Fabian
Published: February 2024

Owing to a shared common technological basis, monovalent K-ion battery (KIB) systems follow in the footsteps of Li-ion batteries (LIBs) with the aim to develop a broader portfolio of available battery technologies and to put them on a more sustainable material basis. For example, both cations intercalate into a graphite host structure, which can be used in combination with carbonate-based electrolytes as negative electrode. Especially in half cells, the degradation of graphite electrodes in KIBs is significantly accelerated in comparison to LIBs. Previous surface studies demonstrated that the formation of a durable and protective solid electrolyte interphase (SEI), that is paramount for long cycle life in alkali-ion batteries, is a major bottleneck for KIBs because of less benign SEI properties[1][2].

Recently reported crosstalk phenomena in half cell configurations due to the highly reactive potassium counter electrode make the analysis of surface layers a particular challenge [2][3]. In this presentation, a detailed characterization of the SEI formation on graphite was performed in both half and full cell configurations by in-house and synchrotron-based photoelectron spectroscopy (PES) in order to demonstrate fundamental differences in surface layer composition under the influence of a reactive counter electrode. While it is generally acknowledged that PES results show differences in SEI composition and thickness between both configurations, our results clearly demonstrate that in case of KIBs the changes become severe. This challenges interpretations of SEI layer properties made in half cells, as they are distinctly different from those in full cells. More importantly, this also affects interpretations on the major electrolyte degradation pathways in these systems. Using PES depth profiling and complementing results with gas chromatography, as well as DFT calculations, delivers new insights on the irreversible processes in KIBs.

Reference
s
:

[1] Naylor, et al., ACS Appl. Mater. Interfaces. 11 (2019) 45636–45645.

[2] Allgayer et al., ACS Appl. Energy Mater. 5 (2022) 1136–1148.

[3] Hosaka et al., ACS Energy Lett. 6 (2021) 3643–3649.
(Invited) Electrochemical Interfaces in Energy Storage: Theory Meets Experiment
Authors: Vegge Tejs
Published: February 2024

Understanding the dynamic processes at solid-liquid interfaces in electrochemical devices like batteries is key to developing more efficient and durable technologies for the green transition. Fundamental and performance-limiting interfacial processes like the formation of the Solid-Electrolyte Interphase (SEI) [1,2] and dendritic growth [3] span numerous time- and length scales. Despite decades of research, the fundamental understanding of structure-property relations remains elusive. Ab initio molecular dynamics (AIMD) generally provides sufficient accuracy to describe chemical reactions and the making and breaking of chemical bonds at these interfaces [4]. Still, the cost is prohibitively high to reach sufficiently long time- and length scales to ensure proper statistical sampling [5]. Machine learning (ML) potentials offer a potential solution to this challenge. Still, training ML-based potentials capable of handling activated processes in organic or aqueous electrolytes remains a fundamental challenge since the potential must capture both intra- and intermolecular interactions in the electrolyte and during chemical reactions at the interface [5]. Here, we present new approaches using phase field models [3], graph neural networks [6] and new transition state training sets [7] for chemical reaction networks, and machine/deep learning models to predict the spatio-temporal evolution of electrochemical interphases [2]. We also discuss the development of methods like symbolic regression to learn the laws of electrolyte transport [8], uncertainty quantification training and evaluating neural network ensemble models [9] using models trained on multi-sourced and multi-fidelity data from multiscale computer simulations, operando characterization, high-throughput synthesis, and testing, to provide, e.g., uncertainty-aware and explainable ML for early prediction of battery degradation trajectories (Figure 1) [10].

Figure 1
Novel Approaches for Improving Solubility of Pyridinium Anolytes in Non-Aqueous Redox Flow Batteries
Authors: Hickey David P. , Samaroo Sharmila , Hegensbach Charley , Guarr Thomas F.
Published: February 2024

Organic redox flow batteries (ORFBs) offer significant promise as a means of efficient grid-scale energy storage to compliment the intermittent power supply of renewable energy sources such as solar and wind power. ORFBs efficiently store energy in the form of redox-active organic molecules (ROMs) by passing them over two polarized electrodes to generate an oxidized (catholyte) and a reduced (anolyte) species, which are held in separate tanks until energy is needed. Structural diversity of anolytes and catholytes for ORFBs has expanded dramatically over the past decade as researchers have raced to discover or design ROMs suitable for use in grid-scale energy storage devices; however, a lack of correlations between ROM structure and a desired chemical or physical property has led to a “guess and check” approach that can overlook possibly transformative electrolyte structures. Recent work has demonstrated the ability to employ multivariate regression analysis to correlate computationally derived structural descriptors of ROMs to their corresponding stability. Based on this, we considered the possibility of employing a similar approach to identify quantitative structure-property relationships (QSPRs) for critical physical properties of ORFB electrolytes, such as solubility.

Electrolyte solubility is an essential design characteristic in ORFBs as it directly impacts the corresponding battery’s energy storage capacity. Nevertheless, the fundamental question, “What makes an electrolyte soluble?” (especially in organic solvents) still lacks a concise answer despite decades of progress. As part of a collaboration with the Guarr group at the Michigan State University Bioeconomy Institute, our group has identified a novel class of pyridinium anolytes with exceptionally low redox potentials and highly persistent charged states. We will discuss our group’s recent progress to combine experimental and computational techniques to develop QSPR models to accurately predict solubility of pyridinium anolytes. The resulting models have provided new insights into the role that self-interaction between anolyte species in solution plays in dictating their corresponding solubility. Using these models, we have successfully expanded the solubility range for a class of pyridinium derivatives by >200% in acetonitrile.
(Invited) The Effect of Surfactants on Vanadium Electrochemistry in Porous Carbon Electrodes
Authors: Barth Brian , Zawodzinski Thomas A.
Published: February 2024

We present a study of vanadium electrochemistry in porous electrodes with and without sodium dodecyl sulfate (SDS) additives present. Carbon paper and felt electrodes are compared. Carbon felt electrodes are the de facto standard in flow batteries. There are significant differences in the electronic conductivity of these media. The carbon paper has a much higher conductivity than the felt, which has an electronic conductivity similar to the ionic conductivity of the electrolytes used. The latter fact motivates an extension of available theory for polarization curve fitting to explicitly include both electronic and ionic contributions in the porous electrode. We demonstrate agreement between our model and an existing model evaluated at the limit where electrode conductivity is significantly greater than electrolyte conductivity. Our model uses the product of the electrode surface area per volume ratio and the heterogeneous electron transfer rate constant, and the Damköhler number as fitting parameters for carbon paper and felt electrodes. We discuss the effect of SDS additives on kinetics in the context of the cation hydration shell for the vanadium ions. To this point, we apply Marcus-Hush-Chidsey formalism to our porous electrode model to quantify reorganization energies obtained through polarization curve fitting. This work was supported as part of the Breakthrough Electrolytes for Energy Storage (BEES2), an Energy Frontier Research Center funded by the United States. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409.
Predictable Local Polarization inside Electrodes By Three-Dimensional Multi-Scale Model in Flow Batteries
Authors: Luo Yansong , Zheng Menglian , Wenrui Lv
Published: February 2024

Redox flow batteries (RFBs) are regarded as one of the most promising grid-scale energy storage technologies, which can improve the applicability of wind and solar energy by leveling their fluctuating power output. In RFBs, the gas side reactions including hydrogen evolution reaction and oxygen evolution reaction reduce the efficiency and capacity of the batteries and the gas produced may even cause safety problems. Even if the voltage is controlled in practical applications to restrict the gas side reactions, it is still inevitable due to flow dead zones or insufficient reactants locally inside the electrode. Gas side reactions are usually caused by too high local overpotential, i.e., local over polarization. Therefore, in this work, we propose a multi-scale model that allows the rapid prediction of local polarization to limit and manage the gas side reactions. The multi-scale model contains a deep neural network, a pore network model, and a three-dimensional continuum model with the advantages of both accuracy and extensibility. By learning from the sample data provided by the cell-scale model and the pore-scale model, the deep neural network can quickly predict the local polarization under different operating conditions and give the distribution map of the entire electrode. Compared with conventional models, multi-scale models can take into account the geometry of electrode fibers and are suitable for electrode design and modification. Due to the calculation superiority of the pore network model, the multi-scale model can realize three-dimensional local polarization prediction, which enables a more accurate analysis of the internal uniformity of the electrode. Through the developed model, we explore the effects of the interdigitated flow field, flow rate, initial concentration and voltage on local polarization. It is shown that the multi-scale model can accurately predict local polarization. However, the promotion of flow rate cannot completely eliminate the occurrence of local over polarization.
Investigation of Interfacial Behavior of Ni-Rich NCM Cathode Particles in Sulfide-Based Solid-State Electrolyte
Authors: Mukhan Orynbassar , Yun Ji-Su , Kim Sung-soo
Published: February 2024

All-solid-state batteries (ASSBs) are currently investigated as a future battery technology with conventional layered cathode materials because they can offer benefits in the gravimetric and volumetric energy densities compared to flammable liquid electrolyte lithium-ion batteries with graphite intercalation anode. The solid electrolyte is believed to suppress dendritic growth and low Coulombic efficiency on the lithium metal anode side, which are the key issues for the use of a lithium metal electrode in conventional batteries with liquid electrolyte. Moreover, layered transition metal oxides such as LiNixCoyMnzO2 (NCM, 0 < x, y, z < 1) are one of the most promising positive electrode active material candidates being developed to increase the energy density. In particular, recent studies have shown a tendency to decrease the cobalt content and increase the nickel content to increase energy density and price competitiveness, so high-nickel NCM can be the optimal material suitable for this purpose. However, the remaining interfacial challenges of the cathode / solid electrolyte interface still need to be solved.

Herein, we investigated the kinetics such as charge transfer resistance at the interface between high nickel (Ni0.94) NCM particles and argyrodite (Li6PS5Cl) solid electrolytes using the microcavity electrode with the negative and positive pulsed current measurement technique and compared with liquid electrolytes using the same manner measurement technique. The cavity-electrode system is adopted to analyze the electrochemical properties of active particles and electrolytes confined in the cavity to exclude the effects of surrounding interfaces, barriers, and side reactions caused by battery components around the electrodes and the impact of loading and current collectors of the composite electrode. Therefore, understanding the electrode-electrolyte interface between cathode active particles and solid electrolytes is crucial for theoretical studies on the interfacial phenomenon in solid electrolyte batteries.
(Invited) Confocal Raman Microscopy in the Study of Ion Insertion Processes and Material Dimensional Change
Authors: Korzeniewski Carol , Xu Jiahe
Published: February 2024

Confocal Raman microscopy is being applied to quantify chemical composition at electrode-solution interfaces and within electrode-supported films under electrochemical potential control. Experimental strategies (i.e., cell designs and data acquisition and processing techniques) that are enabling sensitive in-situ spectral measurements will be discussed with focus on redox transformations at electrode-solution interfaces and within electrode-supported polymer membranes and thin films. Emphasis will be on the ability to investigate ion insertion/de-insertion processes and measure material dimensional (e.g., swelling/de-swelling) changes as the applied potential is varied (in-situ).

The microscope system being utilized employs a high numerical aperture oil immersion objective to achieve (i) diffraction-limited focusing and probe volume characteristics and (ii) high efficiency in collecting Raman scattered radiation from molecules of interest. With the objective mounted to an inverted microscope frame, the electrochemical cell is positioned above the objective on the microscope stage. A glass microscope coverslip attached to the bottom of the electrochemical cell serves as the optical window. One electrochemical cell platform has been constructed around an optically transparent indium tin oxide (ITO) coated coverslip that serves as both the cell working electrode and optical window. The objective brings excitation radiation through the coverslip and to a focus a few micrometers above the ITO surface. Species diffusing into the confocal probe volume region are detected and quantified based on their Raman spectral band frequencies and intensities. A second electrochemical cell platform has a thin layer design and enables use of conventional disk working electrodes. The performance of this cell together with a spectral difference technique that allows detection of transformations within redox polymers supported on carbon electrodes will be discussed.

The platform is being applied to detect swelling/de-swelling in electrode-supported redox polymers in response to changes in material redox state. Molecular composition (i.e., the mix of polymer framework, solvent and mobile ions) within the confocal probe volume is measured quantitatively from Raman spectra. Tracking the frequency and intensity of spectral bands as electrode potential is varied enables voltage-induced swelling and de-swelling to be correlated to changes in the composition of specific types of mobile species (solvent and ions). Similar application of the strategy to investigate material dimensional change with variation in atmospheric composition will be highlighted.
Transient Short Circuit-Based Degradation of Lithium and Sodium Anode-Free Batteries
Authors: Menkin Svetlana , Fritzke Jana Beatrice , Larner Rebecca , Grey Clare P.
Published: February 2024

The demand for an extended range of electric vehicles has created a renaissance of interest in replacing the common lithium-ion with a higher energy-density metal anode (e.g., Li or Na). However, alkali metal cells suffer from capacity fading and potential safety issues. The uneven metal electrodeposition often results in dendrite formation and potentially hazardous situations such as cell short-circuiting and thermal runaway.

Though lithium plating has been studied widely, a better understanding of the short-circuiting mechanisms and metal battery failure is required. Moreover, a considerable performance gap exists between symmetric metal cells and realistic metal batteries.

"Soft shorts" are small localised electrical connections between two electrodes that allow the co-existence of direct electron transfer and interfacial reaction. Although soft shorts were identified as a major safety issue in the early nineties, their detection and prevention were not widely studied. Therefore, a fundamental understanding of passivated metals' plating and a reliable testing method for soft short circuits is critical for realising metal batteries, such as Li-Air, Li-S, and anode-free batteries.

Here we compared short circuit formation mechanisms and degradation in symmetric cells and anode-free lithium and sodium batteries using coupled galvanostatic impedance spectroscopy (GEIS) and in-situ nuclear magnetic resonance spectroscopy (NMR) for the first time.

The coupling of in-situ NMR and EIS allows the observation of metal batteries' electrochemical and chemical dynamics and degradation in real time without affecting the cells' operation.

We demonstrated that lithium and sodium short circuit formation mechanisms fundamentally differ and strongly depend on electrolyte composition and SEI stability. This new understanding of the metal plating mechanism is crucial to develop the next generation of rechargeable batteries with high energy density, prolonged cycling life and improved sustainability.
Electrochemical Scanning Probe Microscopy Evaluation of Li-Ion Battery Cathode Degradation through in Situ Oxygen Evolution Measurement and Interfacial Property Characterization
Authors: Mishra Abhiroop , Rodriguez Lopez Joaquin
Published: February 2024

Degradation processes involving oxygen evolution significantly limit the performance, reversibility, and capacity of high energy density Li-ion battery (LiB) cathodes. In addition, oxygen evolution processes create hazardous conditions for LiB operation. Despite the importance of these processes, characterization of evolved O2 with sufficient spatial and temporal versatility is hampered by the complex setups required to perform electrochemical mass spectrometry, the gold standard for evaluating this process. Recently, we introduced a scanning electrochemical microscopy (SECM) approach that enables in-situ, real-time (i.e., few ms temporal resolution), chemically selective detection of O2.[1] Measurements were accomplished by positioning an SECM probe (i.e., an Au ultramicroelectrode) near operating cathode surfaces for detecting O2 via the oxygen reduction reaction (ORR). The superior signal-to-noise of this method enabled the observation of two peaks corresponding to a steady-state evolution at high voltage and a transient O2 evolution at low voltage on materials such as lithium cobalt oxide (LCO) and NMC electrodes.

Here, we expand the capabilities of our technique by incorporating correlated measurements aimed at understanding how oxygen evolution profiles are related to surface electrochemical and mechanical properties. Specifically, we will focus on the use of feedback-mode SECM and the use of reactive mediators to evaluate the changes in the rates of electron transfer measured on materials undergoing O2 and after structural degradation. Furthermore, the use of electrochemical AFM allows us to measure the mechanical properties of these interfaces, in an attempt to tie the structural changes and the evolution of oxidizing species with the formation of cathode-electrolyte interfaces. Altogether, these multimodal SECM and AFM methods elucidate the manifold chemical, structural, and performance changes underpinning LiB cathode operation.

[1] Mishra, A.; Sarbapalli, D.; Hossain, M.S.; Gossage, Z.T.; Li, Z.; Urban, A.; Rodríguez-López, J. Highly Sensitive Detection and Mapping of Incipient and Steady-State Oxygen Evolution from Operating Li-Ion Battery Cathodes via Scanning Electrochemical Microscopy. J. Electrochem. Soc., 2022, 169, 086501.

Figure 1
(Invited) Composite Electrodes – the Challenge of Characterizing Ionic Transport on the Liquid Side of the Solid-Liquid Interface
Authors: Schougaard Steen Brian
Published: February 2024

Composite electrodes are at the hart of modern batteries, since they overcome critical limitations of the solid active materials including volume changes as well as poor electronic and ionic conduction. Due to the very nature of the composite electrodes the solid-liquid interface of electron transfer reaction become buried within the bulk. Moreover, the bulk of the electrode has a complex internal structure, which is exceeding difficult to characterize using even advanced electron and X-ray techniques. This is in part due the nanometric size of the carbon black used to improve electron transport. In this talk, we will present some of our latest development based on scanning electrochemical microscopy and synchrotron radiation to characterize the electrolyte side of the composite electrode. Specifically, we will present data to suggest that the canonical electrolyte transport can be determined in a single sided measurement, greatly simplifying analysis in quality control and providing experimental data for this critical parameter in battery modeling. Moreover, we will present operando measurements of the electrolyte concentration gradient within the composite electrode. This matrix is particularly changeling due to its paramagnetic, conducting and opaque nature. The talk will conclude with an outlook on opportunities and challenges related to these techniques.
Electrochemical Characterization of Artificial Solid Electrolyte Interphase Developed on Graphite Via ALD
Authors: Schlaier Jonas , Fedorov Roman , Huang Shixian , Ein-Eli Yair , Schneider Michael , Heubner Christian , Michaelis Alexander
Published: February 2024

During formation of Li-ion batteries, a ‘natural’ solid electrolyte interphase (SEI) is formed at the anode side by decomposition products of the electrolyte. The properties of the SEI are extremely decisive for the overall battery properties, such as rate capability and cycling stability. However, the SEI formation consumes Li, leading to so called ‘formation losses’ that can make up to 15% of the theoretical energy density of the battery. Several approaches have been presented to overcome formation losses while preserving excellent overall battery properties. Particularly, electrochemical prelithiation and the application of artificial SEIs prior cell assembly are considered to effectively reduced formation losses while improving the interfacial charge transfer properties and increasing cycling stability.

Herein, the authors present an innovative approach of applying a multifunctional artificial SEI on anode material powders via consecutive atomic layer deposition (ALD) cycles. As a model system, graphite powder has been chosen to be modified and characterized.

The resulting electrodes show substantially improved electrochemical performance in half cells and full cells, regarding initial capacity loss, CE and cycling stability. Furthermore, model electrodes consisting of a single layer of graphite particles were manufactured, which exclude the effects of a typical composite electrode and therefore reveal the intrinsic properties of the active material. Using this approach, the interfacial kinetics and the rate capability are investigated comparatively between pristine and ALD coated electrodes, revealing the impact of the artificial SEI on the materials level.
Enhanced Electrochemical Activity Volcanoes in Flat-Band Twisted Trilayer Graphene
Authors: Babar Mohammad , Zhu Ziyan , Kurchin Rachel , Viswanathan Venkat
Published: February 2024

Electrochemical reactions at electrode-electrolyte interfaces are often controlled by modifying the substrate and thereby tuning the adsorption energy to reach peaks of activity volcanoes. In this work, we attempt to enhance interfacial charge transfer kinetics through modifying the electronic density of states of an electrode which offers highly tunable flat bands such as the twisted graphene system, allowing greater overlap with the redox couple states. Correspondingly, we develop a twist-dependent electrochemical activity map, combining a tight-binding electronic structure model with modified Marcus-Hush-Chidsey kinetics in trilayer graphene. We identify a counterintuitive rate enhancement region spanning the magic angle curve and incommensurate twists of the system geometry. At room temperature, we find a broad activity peak with a ruthenium hexamine redox couple in regions corresponding to both magic angles and incommensurate angles, a result qualitatively distinct from the twisted bilayer case. Flat bands and incommensurability offer new avenues for reaction rate enhancements in electrochemical transformations.
Analysis of the Impact of Operating Conditions on Performance of H2 Gas – Aqueous Manganese Redox Flow Batteries
Authors: Farrow Catherine , Mezzavilla Stefano , Pandya Dillon , Ranta Emilia , Fernihough Oliver , Liddington Ben , Kavei Ashkan , von Werne Tim
Published: February 2024

In recent years the need to move to renewable energy sources as a means of combating climate change has become increasingly clear. Long duration energy storage (LDES) is essential for the incorporation of renewable energy generation into grid-scale energy systems. Redox Flow Batteries (RFB) offer a promising solution due to scalability, safety, and cost. The hybrid H2 gas – aqueous Mn RFB has been identified as a candidate1.

Recognising the absence of an established protocol for measurement of RFB system performance, this study uses charge- discharge polarisations to explore the sensitivity of the H2/Mn performance to changes in temperature. When designing a RFB for commercial usage it is important to balance improved performance with the necessary stability that is required for any potential LDES system. In this work we use a developed stress test to demonstrate the impact of temperature on the systems stability.

Varying temperature showed improvement of 2.8 mV/ oC in charging overpotentials of and 5.7 mV/ oC in discharging overpotential. However, this must be weighed against the impact on the stability of the cell. These findings serve as inputs for the development of the control system essential for the successful operation of the H2/Mn RFB system.

1Rubio-Garcia, J. et al. Hydrogen / manganese hybrid redox flow battery. J. Phys. Energy (2018)

1015006.
Characterization of the Photothermal Response in Nanocomposite Silica Aerogel Materials with Thin Metal Films
Authors: Capacchione Amanda , Talebzadeh Nima , Nagi Mubariz , Cooper Thomas , O'Brien Paul , Freire-Gormaly Marina
Published: February 2024

The photothermal effect, whereby light energy is converted into thermal energy when absorbed in a material, is a phenomenon that has many potential applications including solar-driven water heating and purification, and radiative heat transfer. Recently, porous materials have been tailored to exhibit the photothermal effect to be used for interfacial water evaporation and sterilization. In this work we provide the characterization of the solar-driven photothermal effect on nanocomposite aerogel materials. Aerogels exhibit a unique combination of properties that can enhance their utility as a photothermal material. Due to their inherently low density and thermal conductivity, and their exceptional insulative properties, photothermal heat generated within an aerogel can remain trapped. This work presents the photothermal effect in nanocomposite aerogels fabricated by sputtering metal and metal oxide films onto and into aerogels materials. By sputtering metal and metal oxides in a high vacuum environment and directing it towards an aerogel substrate using a magnetron, we were able to deposit thin films onto the surface of an aerogel. The composite aerogels are characterized using scanning electron microscopy (SEM) to assess the depth of the sputtered material into the aerogel pores. The reflectance and transmittance of the aerogel composites are measured using UV-Vis spectroscopy. The photothermal effect in aerogel composites is measured using thermal imaging. Our results show that the photothermal response of the composite aerogels can be tuned by varying the thickness and composition of the deposited films. Overall, our study demonstrates the potential of using magnetron sputtering to create composite aerogels with tailored photothermal properties. This opens new opportunities for a wide range of applications such as water and air heating and purification, water desalination, and solar energy harvesting devices.
Non-Equilibrium Nitrate Detection in Ionophore-Based Solid-Contact Ion-Selective Electrodes
Authors: Gettler Ryan , Young Matthias , Mehregan Shima , Koenig Henry D
Published: February 2024

Ion-selective electrodes (ISE’s) have benefits for solution-phase detection and quantification of ions, such as ease of operation, low cost, and high throughput compared to, e.g., ion chromatography or mass spectrometry methods. ISE devices are traditionally operated under zero-current conditions, where analyte ions passively exchange across a selective membrane barrier, yielding a Nernstian response after equilibration of Coulombic and chemical driving forces across the membrane. However, this passive mode of operation can require long equilibration times and lead to drift, for example due to electrolyte leakage and pH impacting the membrane and reference electrode. In recent years, non-equilibrium detection techniques have been of growing interest, where the ISE signal is obtained under applied electrical signal. However, the majority of this work has been devoted to cation sensing, with relatively few studies examining anion ISEs under active electrical actuation. Agricultural expansion and the corresponding uptick in application of supplemental nitrogen to soil has led to an increased demand for technologies to measure anions like nitrate – both from a production and regulation standpoint. In this work, we employ galvanostatic polarization of solid-contact ISEs as a non-equilibrium nitrate detection method. Our investigation involves coating electrodes with a redox-active charged polymer to act as a transduction layer to convert ionic to electronic signal, followed by solvent casting of a polymeric ion-selective membrane. We examine the impact of repeated rapid charging and discharging ISE electrode stacks on measurement time and stability. We compare the metrics derived from this technique to conventional open-circuit measurements using the same device. We identify benefits for this mode of operation using established nitrate membrane materials (e.g. nitrate ionophore VI membrane cocktail) that address some of the typical limitations of these conventional materials and we discuss opportunities for further refinement.
An Electrochemical Approach to in-Situ Continuous Soil Nitrate Monitoring
Authors: Eldeeb Mohammed , Dhamu Vikram Narayanan , Paul Anirban , Muthukumar Sriram , Prasad Shalini
Published: February 2024

Soil nitrogen is the most limiting nutrient affecting plant growth. However, due to poor soil management due to lack of soil health information, high-N fertilizer use increased exponentially. The UN has labeled nitrogen pollution one of the most important pollution issues facing humanity[1]. Not only does it affect life on land and underwater, it is also 300 times more potent at heating the climate than carbon dioxide while remaining active for 100 years in the atmosphere. Currently, soil nitrogen assessment techniques require destructive sampling where a soil core is collected then shipped to a lab to measure nitrogen content. Not only does this technique have high costs, it only measures nitrogen levels at that specific time point. In this work, we utilized commercially available screen printed electrodes (SPE) with a nitrate ionophore for low cost real-time continuous tracking of soil nitrate levels. The ionophore coating utilizes tetradodecylammonium nitrate (TDDA) as the selective reagent as it’s highly specific to nitrate ions. Previous work done using TDDA used open circuit potential (OCP) to measure nitrate concentration. Soil water content, pH, environmental noise, and other ions impact OCP thus making it unreliable for long term continuous measurements. This work utilizes electrochemical impedance spectroscopy (EIS) instead as it is more robust against the previously mentioned parameters. By opting to use a higher frequency of 1 kHz to extract nitrate concentration, we avoid environmental noise that are dominant at lower frequencies. The sensor output was calibrated in three different soil textures from 2 – 512 ppm presented in Fig. 1(a) for Clay soil. Then the sensor accuracy was validated to the gold standard cadmium reduction method presented in Fig. 1(b) showing non-significant differences with one sample only having a *p-value of 0.049. Lastly, the sensor stability was measured for 7 days continuously in soil with a coefficient of variation of 17% which is under the acceptable standard 20%.

Figure 1 (a) Calibrated dose response for Clay soil with 50% water content. (b) vaidation of proposed sensor against gold standard in various soil types. (c) longitudinal study showing stablity and consistency of sensor performance in-situ

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Monitoring Electrochemical Signals from Sacrificial Coatings for Pipeline Materials with Membrane-Based Sensors
Authors: Rendon Arnaldo , Belarbi Zineb , Lvov Serguei N. , Dogan Omer , Hall Derek M.
Published: February 2024

Monitoring internal corrosion within pipelines is essential to the safe management of gas transportation infrastructures. Membrane-based electrochemical sensors are a promising new method of monitoring corrosion risk, as they can operate in humidified gas environments which were previously inaccessible to conventional electrochemical monitoring methods. In parallel, new sacrificial coatings and coating application methods are being explored to extend the lifetime of existing pipeline structures and minimize repair costs. Herein, we extend the use of membrane-based electrochemical sensors to examine the response of electrodes with sacrificial coatings for a series of fluids with varying extents of corrosivity applicable to natural gas pipelines. Multiple sensors with X65 steel working electrodes were coated then exposed to humidified gases with differing relative humidities (RH) (5 , 50 , and 95 %) and condensed phases with differing salt content (deionized water and 0.1 mol kg-1 NaCl solution). Three electrochemical techniques (potentiometry, impedance spectroscopy and potentiodynamic scans) were used to monitor the corrosive environment and probe the extent of coating coverage. For the conditions studied, impedance values were extremely sensitive to changes in water content through changes in the membrane resistance (from ~1 kΩ in deionize water to ~10 MΩ with 5 % RH). Polarization resistances (Rp) consistently decreased with increasing corrosivity (~10 kΩ in deionized water to 1 MΩ with 5 % RH). Of the methods used, open circuit potential (OCP) values were the most sensitive to the presence of a sacrificial coating. Fully coated samples typically had OCP values 0.2 V lower than uncoated and partially coated samples in humidified environments, suggesting this sensing method made provide a means to monitor coating lifetime.
Amine-Functionalized Pencil Graphite Electrode for Simultaneous Determination of Dopamine and Uric Acid
Authors: Kabiraz Dulal Chandra , Ahmed Shahed
Published: February 2024

In this study, an electrochemical transducer based on an Amine-functionalized cheap and disposable pencil graphite electrode (NPGE) is proposed for the simultaneous monitoring of Dopamine (DA) and Uric Acid (UA) in biological samples such as serum and urine. The prepared NPGE was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that the incorporation of amine groups significantly improved catalytic activity than the bare pencil graphite electrode (BPGE). Moreover, the electrode modification parameters and effects of different analytical variables such as sweep rate, pH of the supporting electrolyte solution, and possible interfering ions or molecules in quantification were optimized using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized conditions, DA and UA oxidation currents showed linear responses over the concentration range of 1.06-160 µM for DA and 30.06-150 µM for UA. The limit of detection (LOD) for DA and UA were estimated to be 0.94 and 1.26 µM, respectively. In addition, the transducer’s sensitivity of 5.47 µA.µM-1cm-2 for DA and 1.70 µA.µM-1cm-2 for UA were calculated. Aiming to reuse the transducer, a regeneration solution is proposed which could successfully remove the adsorbed oxidized products from the surface. Finally, the developed transducer’s performance was compared with the established clinical method.

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Electro-Structured Cu Distorted Nanopyramids for Superior Sweat Glucose Sensing
Authors: Srinivasa Rao Vusa Chiranjeevi , Gokhale Nachiket , Panda Siddhartha
Published: February 2024

There is a rising global demand for non-invasive glucose monitoring devices, due to an increase in diabetes and its associated health problems. Nanostructures, including needles, fibers, and rods, have drawn considerable attention due to their unique structural-based physical and chemical features in non-enzymatic electrochemical sensing. Copper is a potential candidate for applied research because of its higher electrical conductivity, low cost, and strong reactivity. To create 3-D nano copper structures, researchers have investigated chemical, electrochemical, and hydrothermal techniques. The electrochemical method can better control the formation reaction for these structures. The electrochemical process has better control over the formation reaction for these structures.

Distinctive and self-supported copper nanopyramids were electrochemically created on a copper substrate within a few seconds by electrochemical deposition in a one pot synthesis. The SEM image of the constructed nano copper pyramids are shown in figure 1a. The built nano pyramids have a length of ~200 nm. The generated nanostructures display excellent catalytic activity for non-enzymatic glucose sensing. The created nonenzymatic sensor was tested for glucose detection in synthetic sweat and it displayed a linear response in the range of 20 µM- 2000 µM, making it appropriate for practical applications. The chrono amperometry for glucose sensing was performed at 0.5V for 60s. Figure 1b shows the calibration plot for glucose sensing. Linear response for the glucose was observed in the range from 20µM – 2000µM. The device showed a very low interference for uric acid and ascorbic acid. The device is stable upto 60 days, highly reproducible and can be reused upto 5 times. The correlation coefficient was 0.9857 for the linear equation I(μA) = (9.52*10-3) *C (in µM) + 5.065 and a sensitivity of 1.17 nA/(μM-cm2) was observed

Figure 1