bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction to the Principles of Electrochemistry through an Affordable Hands-on Electrochemical CO2 Reduction Experiment
Authors: Medvedev Iurii , Krivoshapkina Elena , Klinkova Anna
Published: September 2023

We are grateful for the invitation to this session by Prof. Alice H. Suroviec. Electrochemical conversion of CO2 to useful chemicals and synthetic electrochemistry in general are rapidly developing and expanding areas of research and industrial application, which necessitates developing undergraduate curricula that will help students build and retain a strong foundational knowledge in this area of chemistry. Currently, there is a limited set of electrochemistry experiments that undergraduate students are typically exposed to in the laboratory, and synthetic electrochemistry is generally limited to water electroreduction to generate hydrogen gas. As a result, students develop limited knowledge, interest and appreciation of synthetic electrochemistry. At the same time, students today are more inclined to learn about methods and concepts that are important for climate action and sustainable development. With this motivation in mind, we developed a laboratory experiment designed to actively engage students in the learning process and help them understand synthetic electrochemistry through a hands-on experience involving CO2 electroreduction. In general, CO2 electroreduction can yield many different chemicals and requires complex and expensive electrochemical workstation and analytical instrumentation to identify and quantify the products, making it prohibitive for wide adaptation in undergraduate laboratories. Here, we propose a simple and affordable setup that still allows students to directly experience all the necessary steps of the process. The proposed laboratory experiment involves testing the performance of different cathodic electrocatalysts in CO2 reduction reaction conducted in a DIY divided electrochemical cell by measuring the produced CO gas with a CO meter using affordable and broadly available supplies. The students learn the importance of the electrocatalyst composition by changing the material of the cathode and observing different amounts of CO produced or the absence of CO when using the electrode selective for only water reduction. They learn about the influence of the applied potential on the reaction rate by changing the battery voltage and observing the quantitative difference in the produced gas. The experiment is designed to be safe when conducted on a standard laboratory bench (i.e., carbon monoxide concentrations outside of the cell are below the threshold of a standard CO detector).
Coral-like N-Doped Cd(O,S) Photocathodes with Oxygen Vacancies for Enhanced Hydrogen Generation
Authors: Abdullah Hairus , Shuwanto Hardy , Lie Jenni
Published: September 2023

Solar-driven hydrogen (H2) production is considered one of the most sustainable methods for clean energy generation to replace fossil fuel-based energy. Herein, we report a highly efficient 3D coral-like N-doped cadmium oxysulfide (Cd(O,S)) photocathodes for hydrogen evolution reaction (HER) in an alkaline solution. The N5-Cd(O,S) achieved an onset potential of 0.63 VRHE with a photocurrent density of 0.74 mA.cm-2 at 0 VRHE, and solar-to-hydrogen efficiency (hSTH) of 6.6 %. For practical application, the amount of evolved H2 by N5-Cd(O,S) photocathode was 12.3 mmol.cm-2 performed at 0 VRHE, improved 2-folds from Cd(O,S) without N dopant. Moreover, N5-Cd(O,S) exhibited excellent stability of 95.8 % for over 10 h HER testing. This work reveals that N5-Cd(O,S) photocathode can capture incident light efficiently with the 3D coral-like microstructure. In addition, the contained oxygen vacancies (OVs) in N5-Cd(O,S) play a dominant role for photoelectrochemical H2 generation.
(Invited) Modeling the Charge Transfer Reactions at Li/SEI/Electrolyte Interfaces in Lithium-Ion Batteries
Authors: Qi Yue
Published: September 2023

Two kinds of charge transfer reactions are critical for the performance and life of lithium battery: the desired ion transfer reaction occurring during each charge/discharge cycle, , and the undesired electron transfer reactions leading to the parasitic chemical decomposition of the electrolyte and solid electrolyte interphase (SEI) formation/growth. The heterogeneous multi-component nature of SEI dominates its ionic and electronic transport properties and controls these two charge transfer reactions. Density Functional Theory (DFT)-informed multiscale modeling has been providing valuable insights under the scarcity of quantitative experiments. For example, the LiF/Li2CO3 interface was demonstrated to increase the ionic conductivity of mixed SEI nanocomposite by forming an ionic space charge region near the interface and promoting more Li-ion interstitials in Li2CO3, although LiF itself has low Li-ion conducting carriers and conductivity. To form a LiF-rich SEI layer, the electrolyte compositions need to be designed. Since the SEI formation occurs on the charged surface, the electric double layer (EDL) structure near the charged surfaces needs to be incorporated into the modeling. Here interactive classical molecular dynamics (MD), DFT, and data statistical analysis were combined to illustrate the effect of EDL on SEI formation in two essential electrolytes, the carbonate-based electrolyte for Li-ion batteries and the ether-based electrolyte for batteries with Li-metal anodes. It was found the effectiveness of adding fluoroethylene carbonate (FEC) to form the beneficial F-containing SEI component (e.g., LiF) varies with the electrolyte and temperature, because of the interplay of ion-solvent interactions with the surface charge. These integrated modeling provided quantitative guidance for electrolyte/SEI/Li-metal interface design.
(Invited) Understanding Ion-Ion Correlations: From Liquid Electrolytes to Polymer Electrolytes
Authors: Zhang Chao
Published: September 2023

Mass transport in electrolytes is one of the most important design focuses of electrochemical devices such as batteries, fuel cells, and supercapacitors. Compared to the infinitely dilute solution, ion-ion correlations play a central role in determining the structure-property relationships in the concentrated solution. Therefore, disentangling ion-ion correlations and establishing their impact on transport coefficients is a fundamental and pressing issue in the field of electrolyte materials.

In this talk, I will present the recent works of my group and collaborators on using molecular dynamics simulations to understand ion-ion correlations. In particular, we looked into this issue by exploring the synergy between liquid electrolytes and polymer electrolytes following the physical chemistry route started by Onsager. This has led to a number of interesting results on the relationship between the ion-pairing and the deviation from the Nernst-Einstein relation [1-3], and shed light on resolving the controversy of the negative transference number found in polymer electrolytes [4].

References:

[1] Y. Shao, M. Hellström, A. Yllö, J. Mindemark, K. Hermansson, J. Behler, and C. Zhang, “Temperature effects on the ionic conductivity in concentrated alkaline electrolyte solutions”, Phys. Chem. Chem. Phys. 2020, 22: 10426.

[2] Y. Shao, K. Shigenobu, M. Watanabe, and C. Zhang, “Role of viscosity in deviations from the Nernst–Einstein relation”, J. Phys. Chem. B, 2020, 124: 4774.

[3] H. Gudla, Y. Shao, S. Phunnarungsi, D. Brandell, and C. Zhang, “Importance of the ion-pair lifetime in polymer electrolytes”, J. Phys. Chem. Lett.,
2021, 12: 8460.

[4] Y. Shao, H. Gudla, D. Brandell, and C. Zhang, “Transference number in polymer electrolytes: mind the reference-frame gap”, J. Am. Chem. Soc.,
2022, 144: 7583.
Towards Predicting Metal Extraction from Oxides with Machine-Learning Augmented First-Principles Calculations
Authors: Gharakhanyan Vahe , Garrido Torres Jose Antonio , Urban Alexander
Published: September 2023

The experimental characterization of high-temperature (electro)chemistry for the extraction of metals from their ores or spent electronics is challenging and requires specialized equipment. CALPHAD simulations can be an alternative but require assessed phase diagrams for the system of interest. On the other hand, first-principles calculations can provide robust estimates of many materials properties at zero Kelvin without experimental input, but simulating processes at high temperatures is computationally demanding and often too approximate. Here, we discuss the initial steps toward the efficient computational prediction of chemical reactions and process conditions using machine-learning augmented first-principles calculations. We show that a combination of zero-Kelvin density-functional theory (DFT) calculations and machine-learning models trained on temperature-dependent reaction-free energies allows predicting reduction temperatures of metal oxides (Garrido Torres et al., Nat. Commun.
12, 7012, 2021). An application to crystalline binary and ternary oxides demonstrates that the temperature dependence of the free energy can be cross-learned, removing the limitation to compounds that have previously been thermodynamically assessed. We also show recent progress in extending this approach to the prediction of melting temperatures.
(Invited) Toward Rigorous Modeling of Metal-Metal, Metal-Oxide and Oxide-Oxide Interfaces for the Electrochemical Oxygen Cycle
Authors: Zeng Zhenhua
Published: September 2023

To achieve Net-Zero Emissions by 2050, hydrogen and hydrogen fuel cells will play a significant role in powering vehicles. In this presentation, I will show, through first-principles-based modeling, how to achieve rigorous modeling of solid-solid interface for the hydrogen and oxygen evolution reactions in electrolysis and the oxygen reduction reaction in fuel cells; and how the fundamental understanding paves the way toward developing both model electrocatalysts and industrial electrocatalysts with significantly improved performance. Specifically, I will introduce the following three topics.

[1] metal-metal interfaces: strain evolution and strain tuning of epitaxial, stepped and free-standing platinum group metals for the oxygen reduction reaction in fuel cells.(1)

[2] metal-oxide interfaces: stability and activity of monolayer oxide/Pt interface toward improving the hydrogen evolution reaction in alkaline conditions.(2)

[3] oxide-oxide interfaces: self-consistent modeling of active phases, reaction centers, and catalytic mechanisms of Ni- and Co-based layered double hydroxides for the oxygen evolution reaction.(3, 4)

L. Wang, Z. Zeng, W. Gao, T. Maxson, D. Raciti, M. Giroux, X. Pan, C. Wang, J. Greeley, Tunable intrinsic strain in two-dimensional transition metal electrocatalysts. Science
363, 870-874 (2019).

Z. Zeng, K.-C. Chang, J. Kubal, N. M. Markovic, J. Greeley, Stabilization of ultrathin (hydroxy)oxide films on transition metal substrates for electrochemical energy conversion. Nature Energy
2, 17070 (2017).

F. Dionigi, Z. Zeng, I. Sinev, T. Merzdorf, S. Deshpande, M. B. Lopez, S. Kunze, I. Zegkinoglou, H. Sarodnik, D. Fan, A. Bergmann, J. Drnec, J. F. d. Araujo, M. Gliech, D. Teschner, J. Zhu, W.-X. Li, J. Greeley, B. R. Cuenya, P. Strasser, In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution. Nature Communications
11, 2522 (2020).

F. Dionigi, J. Zhu, Z. Zeng, T. Merzdorf, H. Sarodnik, M. Gliech, L. Pan, W.-X. Li, J. Greeley, P. Strasser, Intrinsic Electrocatalytic Activity for Oxygen Evolution of Crystalline 3d-Transition Metal Layered Double Hydroxides. Angew. Chem., Int. Ed.
60, 14446-14457 (2021).

Figure 1
Li Transport in Defected LiNiO2 from First Principles: Diffusion, Nucleation, and Charge Transfer
Authors: Xiao Penghao
Published: September 2023

Electrochemical intercalation of Li in battery electrodes involves a few types of kinetic processes, including diffusion in inhomogeneous media, phase nucleation/transition, and surface charge transfer. They span several length and time scales and are often coupled with each other, which makes it challenging to identify the rate-limiting step and extract kinetic parameters by fitting an empirical model. Using layered cathode LiNiO2 as an example, I will present how all these processes can be incorporated in one atomistic model without empirical inputs, which reals the kinetic competition between different processes. In this scheme, the energetics of various local environments were calculated by the density functional theory (DFT). And the obtained data were used to train a surrogate Hamiltonian with the cluster expansion method. Then the kinetic Monte Carlo (KMC) simulations were conducted with ion hopping barriers updated on-the-fly based on the Brønsted−Evans−Polanyi (BEP) relation. The charge transfer barriers at the electrode-electrolyte interface were calculated separately using the constant-voltage eNEB method1.

The simulation results shown below largely reproduce the experimental voltage profile of LiNiO2
2. Both the hysteresis and the irreversible capacity loss (IRC) at the first discharge are captured. The rate limiting step switches as the Li concentration changes during cycling. Moreover, the layered LiNiO2 is never perfect and there are always some excess Ni in the Li layer, which significantly affects the electrochemical performances. My simulations peek into the atomistic origins of these effects. The excess Ni formed in the bulk during synthesis increase IRC by impeding Li diffusion3; the excess Ni near the surface formed during cycling due to oxygen loss traps Li in the fatigued particles by suppressing Li-poor phase nucleation below certain Li concentration4.

References:

Duan, Z. & Xiao, P. Simulation of Potential-Dependent Activation Energies in Electrocatalysis: Mechanism of O-O Bond Formation on RuO2. Journal of Physical Chemistry C
125, 15243–15250 (2021).

Kurzhals, P. et al. The LiNiO2 Cathode Active Material: A Comprehensive Study of Calcination Conditions and their Correlation with Physicochemical Properties. Part I. Structural Chemistry. J Electrochem Soc
168, 110518 (2021).

Phattharasupakun, N. et al. Correlating Cation Mixing with Li Kinetics: Electrochemical and Li Diffusion Measurements on Li-Deficient LiNiO2 and Li-Excess LiNi0.5Mn0.5O2. J Electrochem Soc
168, 090535 (2021).

Xu, C. et al. Bulk fatigue induced by surface reconstruction in layered Ni-rich cathodes for Li-ion batteries. Nat Mater
20, 84–92 (2021).

Figure 1
Toward Understanding Interfacial Phenomena of Anion Exchange Membrane Water Electrolyzers: Investigating the Role of Electrolyte pH Gradient with Operando Raman Spectroscopy
Authors: Maxwell Derrick , Kendrick Ian , Mukerjee Sanjeev
Published: September 2023

There is growing industrial appeal of anion exchange membrane water electrolyzers (AEMWEs) to produce hydrogen. A significant challenge remains that AEMWE durability testing is not standardized, and more minute interfacial degradation mechanisms between ionomer, catalyst, membrane, and electrolyte are not well characterized. Of particular interest is the impact of electrolyte selection on the polarization performance. There is a general desire to achieve reliable operation with environmentally obtained saltwater as the electrolyte, although this presents numerous challenges manifesting in typically poor long-term durability. Saltwater presents complexities in determining electrolyzer component interfacial phenomena.

Performance of AEMWEs is typically benchmarked with hydroxide or carbonate solutions, therefore providing more direct opportunities to study fundamental mechanisms with regards to interactions between surfaces. Of particular interest is the presence of electrolyte anion concentration gradients that depend on the polarization state of the oxygen evolution reaction electrode (OER). We demonstrated in our early work with operando Raman probing of a custom designed spectroelectrochemical cell that there is initial evidence of spatially resolved anion gradients from the OER electrode surface into bulk electrolyte in a half cell configuration. We hypothesize that local pH changes near an electrode surface may impact the polarization via transport limited ion exchange and the relative overpotential of the overall cell, ultimately leading to an iterative and long-term contribution to decaying cell durability.

We continue our work with a series of in-situ Raman experiments with a full cell configuration: OER electrode with PGM free catalyst, hydrogen evolution reaction (HER) electrode with PGM free catalyst, and anion conductive polymer membrane. Both electrodes also contain an ionically conductive polymer, or ionomer, that serves as a binder. By increasing the complexity of the system to match that of an industrially relevant configuration, we aim to probe the spatially resolved pH gradient with both potassium hydroxide and potassium carbonate solutions of varying concentrations. We utilized a custom, 3D printed, flow cell design comprising a sapphire observation window and isolated electrolyte flow chambers.

Operando Raman spectroscopy measurements were conducted primarily with potassium carbonate solutions by tracking the spatially resolved changes in relative peak intensity of carbonate and bicarbonate signatures. With regards to the carbonate-bicarbonate equilibrium, we calculate changes in pH as the probe approaches the surface of an electrode. We finally connect our findings to a proposed mechanism for the interfacial phenomena relative to cell durability as a function of concentration changes and operating voltages.
(Invited) Correlative Spectroscopy to Elucidate the Factors Controlling the Kinetics of Oxygen Evolution
Authors: Stephens Ifan Erfyl Lester
Published: September 2023

It is particularly challenging to catalyse oxygen evolution under the acidic conditions of polymer electrolyte membrane (PEM) electrolysers. All compounds, apart from IrOx and RuO
x
, are catalytically inactive or unstable. In alkaline electrolysers, a wider range of materials are available, including non precious metal oxides based on Co and Ni.

Herein, I will discuss our recent mechanistic studies on model oxygen evolution catalysts, including RuOx, IrOx, doped CoOxHy and NiOxHy.1-6 I will correlate operando spectroscopy to X-ray absorption spectroscopy, to reveal the factors controlling the factors controlling the kinetics for water oxidation. Density functional theory measurements provide a molecular scale explanation for the observed phenomena.

1 Rao, R. R., Corby, S., Bucci, A., Garcia-Tecedor, M., Mesa, C. A., Rossmeisl, J., Gimenez, S., Lloret-Fillol, J., Stephens, I. E. L. & Durrant, J. R.
J. Am. Chem. Soc.
144, 7622, (2022).

2 Bozal-Ginesta, C., Rao, R. R., Mesa, C. A., Wang, Y. X., Zhao, Y. Y., Hu, G. F., Anton-Garcia, D., Stephens, I. E. L., Reisner, E., Brudvig, G. W., Wang, D. W. & Durrant, J. R.
J. Am. Chem. Soc.
144, 8454, (2022).

3 Rao, R. R., Stephens, I. E. L. & Durrant, J. R.
Joule
5, 16, (2021).

4 Bozal-Ginesta, C., Rao, R. R., Mesa, C. A., Xinyi, L., Hillman, S. A. J., Stephens, I. E. L. & Durrant, J. R.
ACS Catalysis
, (2021).

5 Rao, R. R., Kolb, M. J., Giordano, L., Pedersen, A. F., Katayama, Y., Hwang, J., Mehta, A., You, H., Lunger, J. R., Zhou, H., Halck, N. B., Vegge, T., Chorkendorff, I., Stephens, I. E. L. & Shao-Horn, Y.
Nature Catalysis
3, 516, (2020).

6 Roy, C., Rao, R. R., Stoerzinger, K. A., Hwang, J., Rossmeisl, J., Chorkendorff, I., Shao-Horn, Y. & Stephens, I. E. L.
Acs Energy Letters
3, 2045, (2018).
High C-Rate Dynamic Lithium (de)Insertion Pathway Investigated via Synchrotron-Based Operando XRD and Operando Scanning x-Ray Microscopy
Authors: Koo Bonho , Chung Jinkyu , Kim Juwon , Hyun Hyejeong , Fraggedakis Dimitrios , Wang Jian , Kim Namdong , Weigand Markus , Shin Tae Joo , Alsem Daan Hein , Salmon Norman , Bazant Martin Z. , Lim Jongwoo
Published: September 2023

Lithium-ion insertion kinetics fundamentally hinges upon phase transformation behavior during (dis)charging and understanding the rate-dependent kinetics is crucial for the development of high-power batteries. At high c-rates, kinetic hysteresis is amplified and phase evolution becomes heterogeneous and unpredictable. Specifically, discharge becomes more sluggish than charging of most battery electrodes including LiNixMnyCozO2 (NMC) and LiFePO4 (LFP). Here, we developed an operando soft x-ray microscopy to simultaneously observe surface charge transfer and bulk lithium diffusion in facet-controlled individual battery particles over a wide range of cycling rates (0.01 – 10C). Our result unambiguously reveals that dynamic asymmetry between fast charging and discharging originates from auto-inhibitory Li-rich and autocatalytic Li-poor surface domains, respectively. In addition, we developed synchrotron-based operando fast XRD to track phase evolution during fast cycling. We directly observed that sluggish Li diffusion at high Li content induces different phase transformations during charging and discharging, with strong phase separation and homogeneous phase transformation during charging and discharging, respectively. Moreover, by electrochemically manipulating the lithium-ion concentration distribution within NCM particles, phase separation pathway could be redirected to solid-solution kinetics even at 7 C-rate. Our work lays the groundwork for developing high-power applications and ultrafast charging protocols

Figure 1
Carbon Paper-Based C:TiOx Anode Material for Rapid Charge Lib Application
Authors: Wang Jyun-Siang , Shen Yu-Min , Huang Jow-Lay , Chang Chia-Chin
Published: September 2023

As energy issues go viral, the use of lithium-ion batteries is thought to be a practical solution for electric vehicles due to its high specific capacity. However, the poor high-rate capability of the commonly used carbon anodes limits their application. In contrast, we use TiO2 as an anode to mitigate this issue. In the previous work, a non-stoichiometric TiOx nanopowder was fabricated under the influence of a reduced atmosphere to further enhance its capacity. However, due to a lack of interfacial compatibility, the high electrochemical impedance deteriorates the capacity after the first cycle. Thus, in this work, we use the methane treatment to mitigate the issue to enhance the initial coulombic efficiency from 60% to below 30%. The theoretical capacity of TiO2, TiOx, and C:TiOx are all 335 mAh/g. However, with the surface modification, the experimental capacity can improve. Besides, to avoid absorption during X-ray based analyses, we use a carbon paper substrate to mitigate this issue instead of the copper substrate. Herein, we perform an easy and effective method to improve both the ICE and the capacity at the same time by the reduction process followed by carbon doping as the artificial SEI.

The performance of the battery shows that the electrode has a great initial capacity of 1013 mAh/g with 70% ICE, and holds a retention of 700 mAh/g at a rate of 67 mA/g (0.2C) with ~100% CE after formatting. While for the battery without coating, the initial capacity is 752 mAh/g with a 70% ICE and a CE of ~100%, the retention capacity is, however, only 450 mAh/g at the same rate and decreases at a visible speed.

Based on the above ex-situ results, the mechanism during charge and discharge revealed by in-situ measurements is due. We will further use the synchrotron radiation and the in-operando Raman to clarify the phase transformation behavior, especially at a rapid charging rate.
Spatial Confinement of Li Metal in Hollow Microcapsule Hosts Enabled by Heteroatom-Driven Inward Growth
Authors: Kim Siwon , Shin Hong Rim , Lee Jong-Won
Published: September 2023

In recent years, the demand for advanced batteries with high energy densities has increased significantly, along with the growing demand for electric vehicles. Li metal has garnered considerable research attention as a promising anode material because of its high theoretical specific capacity (3860 mAh g−1) and low electrochemical equilibrium potential (−3.040 V vs. standard hydrogen electrode). However, Li metal batteries still have several hurdles in their practical application because Li metal anodes experience infinite volume expansion, which induces continuous rupture and formation of solid-electrolyte interphase (SEI) layers. This leads to electrolyte consumption and corrosion of Li metal, resulting in a low Coulombic efficiency and poor cycling performance. In addition, the uncontrollable dendrite growth of Li metal may cause early battery failure and safety issues. To address these problems, extensive research efforts have been made, including artificial SEI layers, optimized electrolyte formula, and rational design of three-dimensional (3D) host materials.

Among the various 3D host materials under development, carbon-based materials with hollow structures have been investigated extensively because of their attractive features. The enlarged void space (cavity) of the hollow hosts can accommodate a significant amount of Li deposits, while inhibiting volume changes during plating–stripping cycles. In addition, hollow carbon possesses much lower density than metal-based materials, thereby increasing the specific capacity and energy density. However, the lithiophobic nature of carbon combined with its high resistance to Li+ transport through nanopores on the walls significantly hinders the formation of Li deposits inside the cavity. Li may nucleate on the outer surface of the carbon particles in a nonuniform manner, thereby causing the growth of Li dendrites and electrochemically inactive Li deposits.

In this study, we synthesize metal-organic framework-derived carbon microcapsules with heteroatom clusters (Zn and Ag) on the capsule walls and demonstrate that Ag-assisted nucleation of Li metal alters the outward-to-inward growth in the microcapsule host. The cavity inside the microcapsule host, which was generated by etching with tannic acid, provides large void spaces for Li metal storage. Atomic Ag clusters decorated by a galvanic displacement reaction serve as preferential nucleation sites with a reduced energy barrier and promote the inward growth of Li metal in the cavity, while suppressing nonuniform Li plating on the outer surface. Through combined electrochemical, microstructural, and simulation studies, we verify the beneficial role of Ag-assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host, resulting in enhanced electrochemical performance. This study provides new insights into the design of reversible host materials for practical Li-metal batteries.
Mechanistic Insights into Tyrosine Oxidation Revealed by Fast-Scan Cyclic Voltammetry
Authors: Todorov Jovica , Calhoun Sarah E. , McCarty Gregory S. , Sombers Leslie A.
Published: September 2023

A precise understanding of opioid dynamics in the brain is lacking, largely because few analytical tools are available that are sufficiently sensitive and selective for directly monitoring these important neurochemicals in situ. Tyrosine is a key part of the opioid neuropeptides, and its redox activity can be exploited in their detection. However, a solid understanding of tyrosine electrochemistry on carbon electrodes is first required. It is known that, upon oxidation, tyrosine quickly undergoes chemical transformation to products that foul the electrode, compromising the electrochemical information. This issue can be avoided by using fast-scan cyclic voltammetry (FSCV) which enables collection of well-defined voltammograms on a millisecond timescale before appreciable accumulation of byproducts. In this work, the tyrosine oxidation reaction is characterized and electrode fouling is assessed when tyrosine is incorporated into short synthetic peptides containing other amino acids that are part of the opioid neuropeptides: Gly, Phe, Met, Leu, and Arg. Voltammetric data were obtained in phosphate buffered solution on carbon microelectrodes at scan rates up to 1 kV/s. The results demonstrate the dependence of the peak oxidation potential on solution pH, and identify possible reaction pathways and byproducts that foul the electrode. Peak oxidation potential, peak shape, and ultimately, sensitivity to tyrosine are dependent on the peptide sequence. NMR spectroscopy is used to relate the proximity of proton acceptor/donor functional groups to the electrochemical results in the context of proton-coupled electron transfer (PCET) theory. These fundamental studies are important for the electrochemical detection of important neuropeptides in the complex in vivo environment. Furthermore, a better understanding of the tunability of PCET reaction rates in electrochemical systems has broad implications for technology in a range of areas including artificial photosynthesis, solar energy conversion, and energy storage.
Adsorption and Electropolymerization of p-Aminophenol Reduces Reproducibility of Electrochemical Immunoassays
Authors: Buckey Grace , Owens Olivia E. , Cliffel David E
Published: September 2023

Electrochemical immunoassays are a class of biosensors that achieve high specificity, low detection limits, and low cost attributed to strong antibody-antigen interactions and inexpensive electrochemical instrumentation. Electrochemical assays typically use an enzyme/substrate pair to enable electrochemical signal production. p-Aminophenyl phosphate is a commonly used enzymatic substrate which is hydrolyzed into p-aminophenol (PAP)by alkaline phosphatase. PAP exhibits low oxidation potential and electrochemical reversibility, making it an appealing candidate for assay design. The electrochemical oxidative signal from PAP is increased by its adsorption to the electrode. This is further confirmed by the prevention of PAP adsorption via self-assembled monolayers on gold electrodes reducing PAP’s oxidative current. On bare screen-printed electrodes (SPE), PAP adsorption results in oxidative current variability depending on the electroactive surface area of the working electrode. This variability could not be remedied by cleaning and reusing the same gold SPE. However, adsorption of PAP displays concentration dependence, as the decrease ofthe PAP concentration to 3.8 μM greatly improved the consistency of the measurements. PAP use is also limited in continuous monitoring applications as multiple PAP oxidations on the same electrode caused polymerization. The results from this study suggest that the use of PAP production in immunoassays with SPEs must be fine-tuned and electrodes must be cleaned or disposed of between measurements.
Multivariate Data Analysis of Multisine Impedimetric Fingerprints in Electroanalysis of Biochemical Compounds
Authors: Ryl Jacek , Bogdanowicz Robert , Pierpaoli Mattia , Niedzialkowski Pawel , Olejnik Adrian , Koterwa Adrian
Published: September 2023

While Electrochemical Impedance Spectroscopy (EIS) is found as one of the most versatile tools of electrochemical characterization, it suffers a major drawback when the process in question is non-stationary. On the other hand, Dynamic Electrochemical Impedance Spectroscopy (DEIS) offers an ultra-fast measurement time. DEIS utilizes an approach where all the elementary components are superimposed as one multi-component perturbation signal, offering impedance spectra collection in seconds. This particular advantage allows for the effective use of DEIS in the monitoring of the adsorption processes in multiple fields, such as (bio)sensing, corrosion science, energy storage, or AFM-coupled impedance mapping.

This presentation aims at highlighting the DEIS monitoring utility carried out with changes of an independent variable, such as adsorbate concentration or even under linear polarization sweep. Rapid and accurate determination of adsorption isotherms for green organic corrosion inhibitors or Michaelis-Menten constant for enzyme-based glucose (bio)sensors with DEIS operating in galvanostatic mode and under iDC = 0 were already established. When it comes to impedimetric macromolecular electroanalysis, measuring charge transfer resistance upon analyte adsorption is the most common approach. However, the detection may also base on other factors, such as adsorbed layer capacitance or even disturbance in frequency dispersion of capacitance. Most recently, DEIS under polarization sweep mode allowed us to obtain the unique fingerprint of the electric parameter changes, specific to studied macromolecules (such as DNA strings, viral proteins, RNA polymerase, and enzymes). To effectively use our approach DEIS is combined with multivariate data analysis (principal component analysis with partial least square regression). Multivariate data analysis processes large amounts of generated impedimetric data and defines analyte-sensitive conditions (DC polarization, AC amplitude, frequency range, etc.), which can be done just by using the raw data by the singular-value decomposition method to support the sensing mechanisms. The proposed approach neglects some of the reproducibility issues induced by non-specific adsorption and fouling and reveals the measurement conditions that offer the highest variation of studied parameters upon specific analyte adsorption.

The authors acknowledge the financial support of these studies by the National Science Centre (Republic of Poland) under project 2020/37/B/ST7/03262.
Probe Growth and Degradation of SEI at Multivalent Battery Systems
Authors: Sa Niya
Published: September 2023

Solid Electrolyte Interface (SEI) has not been widely reported for multivalent battery systems. Question such as whether there’s a SEI growth at the interface of the metal anode and the multivalent electrolytes is unclear. How the SEI is formed and its evolution with the electrochemical process is not known. Our lab has spent a great deal of efforts of understanding the role of SEI, its composition and evolution for multivalent electrolyte systems, and this work aims to give an overview of the recent research efforts with the use of the operando electroanalytical methods that reveal the SEI evolution for multivalent battery designs.
Biological Anolyte Regeneration System for Redox Flow Batteries
Authors: Carroll Emily , Simoska Olja , Rhodes Zayn , Petrosky Katia N , Minteer Shelley D.
Published: September 2023

Redox flow batteries (RFBs) are valuable energy storage devices with applications in grid storage, and redox-active small organic molecules (ROMs) have shown promise as charge storage species for RFB applications. However, electrolyte degradation is a common mechanism in RFBs, and the chemical instability of ROMs limits their practical application in commercial RFB devices. Recently, microbial electrochemical technologies have been studied, taking advantage of the natural oxidation microbes undergo when exposed to a carbon source. Here, an aqueous redox flow battery with anolyte phenazine-1-carboxylic acid (PCA) and catholyte (Ferrocenylmethyl)trimethylammonium (FcN) is explored with a genetically engineered, phenazine-producing E. coli
phzAG-SM strain. E. coli phzAG-SM is a genetically engineered bacterial strain that has phenazine gene clusters responsible for producing phenazine species, specifically PCA and pyocyanin (PYO). Standard E. coli strains like E. coli BL21 do not have genes responsible for the phenazine biosynthetic pathways that result in the production of phenazine species. This genetically engineered strain has the ability to not only excrete its own phenazine metabolites, but also to intake the phenazine species present in solution and increase phenazine production rates. In a redox flow battery, the electrolyte species are subjugated to changes in potential during charging and discharging cycles. Over time, the phenazine anolyte species can degrade or decompose. The role of the genetically engineered E. coli in the anolyte chamber is to repair the degraded/decomposed phenazine species, producing a longer lasting battery with more stable phenazine-based electrolyte species. Herein, we demonstrate the design of an RFB system where ROMs are continually regenerated by genetically engineered microorganisms to maintain RFB cycling stability. This work represents a new strategy for improving the stability of RFB systems because, under the influence of genetically engineered microbes, the anolyte species does not display degradation after battery cycling.
(Best Student Presentation) A Calorimetric and Potentiometric Titration Method to Elucidate Ca2+ Solvation Thermodynamics
Authors: Skiba Dhyllan A. , Gallant Betar M.
Published: September 2023

Calcium metal batteries are a promising long-term sustainable alternative to lithium metal batteries due to calcium’s high natural abundance and low electrochemical redox potential. Learning how to control Ca2+ coordination chemistry is essential in enabling high performance and stable calcium batteries. While several spectroscopic and computational studies of Ca2+ coordination have been conducted, they are limited by their qualitative nature and/or require experimental validation. This work introduces a novel methodology using a combination of calorimetric and potentiometric titration techniques, to quantitatively probe electrolyte coordination shell composition, as well as previously unattainable experimental coordination enthalpy, Gibbs free energy, and entropy. To establish the effectiveness of the method, here we investigate the coordination shell thermodynamics in simpler, highly dissociating LiPF6 electrolytes. Starting with a weakly solvated electrolyte, we titrate in a strong solvent—which preferentially coordinates to Li+—and measure the associated heat release/absorption and Li+ potential change with each injection. Fitting both sets of data to a mathematical binding model allows for the extraction of the change in enthalpy (ΔHi), Gibbs free energy (ΔGi), and entropy (ΔSi) associated with each Li+-solvent complex formation. Several weak solvent and strong solvents are investigated to build a dataset of ΔHi, ΔGi, and ΔSi. These thermodynamic values are used to calculate the average coordination number of each solvent in the Li+ coordination shell which agree well with literature. Raman and NMR spectroscopy confirm salt dissociation and solvent displacement during titration. This method unlocks a precise description of the chemical environment around Li+ and enables prediction of the Li+ coordination shell in new electrolytes by rationalizing the hierarchy of solvent binding. Given that this method extends to relevant calcium electrolytes, it is a powerful tool to engineer effective electrolytes for use with a calcium metal anode.
A Model for Lithium-Ion Battery Electrolyte Mixture Densities
Authors: Landry Christian , Bergeron Jacob , Thomas James Chris
Published: September 2023

Lithium-ion battery (LIB) electrolytes are generally composed of an organic hydrocarbon and lithium salt (e.g., LiPF6). The effect of salt addition to the electrolyte solvent increases its density. Experimental density data for basic and realistic, multicomponent mixtures are scarce in the literature, and a predictive model for electrolyte solution density is not yet available. This work resolves to create a predictive method that can be used to estimate the density of these mixtures. A predictive method which accounts for intramolecular forces in the electrolyte mixture was developed and fit to the sparse density data available in the literature. The model exhibited high accuracy for single component electrolyte mixtures with most predictions falling within 1% of measured values and all predictions falling within 5%. The model was further extended to more realistic, multi-solvent electrolyte mixtures which exhibited similar accuracy, seen in Fig. 1. It was noted that the multi-component predictions were moderately worse than for the single component mixtures. The source of this disparity is not clear but may be derived from uncertainty in the data reported by electrolyte vendors and/or the presence of solvent-to-solvent interactions in the solution which are not accounted for in the current modeling framework. In addition to the density model, an accurate method for computing absolute molar and mass fractions of multi-solvent mixtures with specified volumetric concentrations (e.g., 1.2 M LiPF6 in 1:1:1 %vol. EC/ DEC/DMC) is also described for when that is the only known relation for a solution. Computed mass concentration values yielded an average error of 1.4% with a maximum value of 9.6%. The molar and mass approaches were combined to yield a modeling framework capable of computing molar concentrations and densities of all LIB electrolyte solutions based on LiPF6 loaded in any combination of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and propylene carbonate (PC). The largest fault with the final modeling system is that it suffers from a lack of sufficient, high-quality experimental data for validation of its accuracy over a wide range of electrolyte formulations and conditions. This model’s accuracy is dependent on the experimental data utilized for correlation. Accordingly, more data from differing sources will help increase the accuracy and confidence of the model developed herein and allow it for expansive use in LIB fields. Future work will be required to extend the current approach to any novel electrolyte formulations developed in the research and development sector.

Figure 1
Regenerated Ni-Rich Cathode Materials from Spent Li-Ion Batteries by a Closed Loop Process
Authors: Meng Zifei , Kim Jaemin , Hou Jiahui , Ma Xiaotu , Wang Yan
Published: September 2023

The demand for rechargeable lithium-ion batteries (LIBs) has increased exponentially since they were first commercialized by Sony in 1991.[1] Due to the high energy density and excellent cycle stability, LIBs have been widespread utilized in electric vehicles and other applications. However, the lifespan of LIBs is limited. Thus, tons of spent LIBs are generated during the recent decades. More importantly, the price of raw materials, including lithium and cobalt salts, for producing LIBs grows significantly.[2, 3] Therefore, recycling these End-of-Life LIBs becomes a non-negligible part in the whole manufacturing process and hydrometallurgical process is the most common recycling method. Here, our group has demonstrated a closed loop recycling process, combining inorganic acid etching and coprecipitation reaction, to produce regenerated Ni-rich cathode materials. The regenerated LiNi0.83Mn0.06Co0.11O2 shows excellent performance: the first cycle discharge capacity is 214.1mAh/g at 0.05C in the voltage range of 2.8 - 4.3V and the initial columbic efficiency is 90.9%. The performance of our regenerated cathode materials is comparable to commercial cathode materials. In order to further optimize the properties of the regenerated LiNi0.83Mn0.06Co0.11O2, different elements, like Al, with various doping or coating methods will be utilized.

Manthiram A. A reflection on lithium-ion battery cathode chemistry. Nature Communications 2020; 11(1):1550.

Li W, Lee S, Manthiram A. High‐Nickel NMA: A Cobalt‐Free Alternative to NMC and NCA Cathodes for Lithium‐Ion Batteries. Advanced materials (Weinheim) 2020; 32(33):2002718-n/a.

Hou J, Ma X, Fu J, Vanaphuti P, Yao Z, Liu Y, et al. A green closed-loop process for selective recycling of lithium from spent lithium-ion batteries. Green Chemistry 2022; 24(18):7049-7060.
Architecting for Mass Transport: It Is More Than Just Tortuosity
Authors: Resing Anton B , Werner Joerg G
Published: September 2023

Mass transport is performance-defining across energy storage devices. An example of this limitation is evident in energy dense lithium-ion batteries (LIBs), which develop concentration gradients from insufficient transport of lithium-ions (Li-ions) when operated at high current rates. This results in lowered capacity and energy due to underutilized active material and increased overpotential. The movement of Li-ions, or lack thereof is the root cause of the trade-off that exists between energy and power density in LIBs. To alleviate societal demur towards the full adoption of electric vehicles, range anxiety and slow charging are predominant challenges that industry and academia are rushing to overcome. These goals may require reimagined processing methods to move beyond planar electrodes with disorganized and heterogeneous porosity to create architectures that are dense in active material and contain tailored porosity. To maximize the geometric component of diffusion and species flux, porous low-tortuosity channels are a rational design choice, as they act as mass-transport highways for much needed through-plane Li-ion transport.

One such innovative process is hybrid inorganic phase inversion (HIPI), a manufacturing method that is scalable, material-agnostic and results in low-tortuosity free-standing and monolithic architectures with tunable material-to-pore ratios. The HIPI process can enable electrodes with adjustable thicknesses of 100s of µm and relevant micro-architectural feature sizes between 5-40 µm, tailored by tuning the gelation temperature and nucleation density of the inorganic suspension during the nonequilibrium HIPI process. Importantly, the use of a soft organogel casting support results in the unhindered accessibility of the low-tortuosity pores present in the HIPI architectures.

HIPI-architected anode and cathode electrodes exhibit electrochemical and architectural stability over a 1000 cycles in a full-cell battery. Further, mass-transport constraints appear at high current densities, and we identify the lithiation step as rate-performance limiting, a result of insufficient Li-ion supply and concentration polarization. Thus, for energy and power dense LIBs the answer is not simply mass-transport highways as unoptimized low-tortuosity channels, rather in-plane Li-ion demands must be tethered to the through-plane transport. Our results demonstrate the need for and feasibility of tailored electrode architectures where dimensional ratios between low-tortuosity channels, the charge-storing matrix, and electrode thickness are tunable, to both understand multi-scale structure-performance relationships and meet coupled power and energy-storage requirements.

References:

[1] Resing, A. B., et. al., Adv. Mater.

2022

[10.1002/adma.202209694]

Figure 1
A Green Closed-Loop Process for Selective Recycling of Lithium from Spent Lithium-Ion Batteries
Authors: Wang Yan , Hou Jiahui
Published: September 2023

We developed a highly selective recycling process to recover lithium from spent lithium-ion batteries with the easily degradable formic acid. The lithium can be completely extracted with a leaching efficiency of 100%. Other elements are rarely leached out with lithium with a leaching efficiency of lower than 5%, indicating a highly selective extraction only for lithium. The purity of recovered lithium carbonate is as high as 99.994% with an impressive recycling rate of 99.8%. In addition, the formic acid is reusable, which means that our proposed process does not produce any secondary waste.