bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Layered Electrodes for Lithium-Ion Batteries
Authors: Li Jianlin , Kalnaus Sergiy , Livingston Kelsey , Wood David L.
Published: July 2021

Development of lithium-ion batteries has dramatically boosted market adoption of electric vehicles. However, extending driving range is still necessary to further widespread adoption of lithium-ion batteries in electric vehicles, which relies on increased energy density. Increasing electrode areal loading is one effective approach to boost energy density as it reduces the weight fraction of current collectors and the volume fraction of separators, which do not contribute to battery capacity [1]. However, increased energy density in thick electrodes is usually achieved at the expense of power density mainly due to transport limitation of lithium ions through the porous electrodes. This results in electrolyte depletion and lower utilization of the electrodes [2].

To tackle the sluggish mass transport rates, novel electrode architectures are required. There have been various methods for creating unique electrode architectures to reduce electrode tortuosity and facilitate lithium ion diffusion, including laser ablation, co-extrusion, advanced slot-die coating, and freeze tape casting [3-5]. In this presentation, we will discuss design of layered electrodes for superior energy and power performance. Results from both experiment and simulation are included where effect of particle size of active materials, thickness ratio between layers and electrode porosity in each electrode layer were explored. It is demonstrated that the appropriate layered structure can more than double the power density compared to a traditional one.

Acknowledgment

This research at Oak Ridge National Laboratory (ORNL), managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Advanced Manufacturing Office (AMO).

References:

[1] Jianlin Li, Zhijia Du, Rose Ruther, Seong Jin An, Lamuel David, Kevin Hays, Marissa Wood, Nathan Phillip, Yangping Sheng, Chengyu Mao, Sergiy Kalnaus, Claus Daniel, and David Wood, JOM, 89(9) (2017), 1484-1496.

[2] Zhijia Du, David Wood, Claus Daniel, Sergiy Kalnaus, and Jianlin Li, Journal of Applied Electrochemistry, 47 (2017) ,405-415.

[3] Corie Cobb, Scott Solberg, Journal of The Electrochemical Society 164 (7) (2017) A1339.

[4] Y. Zheng, H. J. Seifert, H. Shi, Y. Zhang, C. Kubel, W. Pfleging, Electrochimica Acta 317 (2019) 502.

[5] Ruhul Amin, Benjamin Delattre, Antoni Tomsia, and Yet-Ming Chiang, ACS Applied Energy materials, 1 (2018) 4976.
Alignment Design in Consideration with Tertiary Current Distribution of Thick Electrodes
Authors: Oh Hyeseong , Jeong Kyeong-Min
Published: July 2021

With the increasing demands of lithium-ion batteries in electric vehicles (EVs) and energy storage systems (ESSs), high energy density and extreme fast-charging (XFC) characteristics are required. The easiest way to design high-energy-density cells is to make thick electrodes by minimizing separators and current collectors and maximizing active compounds, but for thicker electrodes, the kinetic losses increased with C-rate, and cycle stability deteriorated.1 On the sidewall of an electrode, there exists a current difference due to the current distribution by the location. This effect gets maximized in case of the thick electrode because there is a non-uniformity of the kinetics through the electrode thickness direction due to the difference of ionic and electronic conductivity within the pores of the electrode. Besides, different alignment margin of cathode and anode causes another current distribution on the sidewall.

In this study, pouch full cells with different alignment margin of LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode and graphite anode are considered to investigate the difference of the current distribution. N/P ratio is set under 1 to induce complete intercalation of lithium-ion from the cathode into graphite anode so that distinguish the capacity from lithium-ion intercalation and lithium plating onto the surface of an anode. Through the calculation of the current distribution of the edge of the thick electrode, the optimal alignment design of the anode is suggested. There exists the optimal alignment margin of anode and cathode with respect to the dimension of the electrode and the current density (C-rate) applied into the electrode.

References

Kuang, Yudi, et al. "Thick electrode batteries: principles, opportunities, and challenges." Advanced Energy Materials
33 (2019): 1901457.
Cold Plasma Process for Lithium-Ion Electrode Manufacturing
Authors: Liang Zhiming , Liu Tuo , Ziegelbauer Joseph Michael , Liu Lu , Gayden Shawn , Ban Chunmei
Published: July 2021

Conventional slurry-cast manufacturing of Lithium-ion battery (LIB) cathode containing active materials, conductive carbon, binders, and organic solvents is expensive and environmental unfriendly due to the long drying process (solvents evaporation). Here, we apply a new, completely dry powder process to manufacturing (LIB) cathodes which includes the use of multiple atmospheric plasma streams to activate cathodes particles for manufacturing high-density and thick LIB cathodes. In this presentation, we use Lithium iron phosphate (LFP) as an example to elaborate this drying process and discuss the effectiveness of the cold-plasma process on electrode manufacturing. During the cold-plasma process, LFP power together with a metallic binder (aluminum herein) were directly co-deposited on the current collector with a superb control of thickness. This presentation will discuss the effects of loading LFP thickness, particles size, and surface chemistry on the electrochemical properties and the cycling performance. XPS and in situ XRD analysis are also used here to better understand the LFP phase evolution and surface chemistry at different electrochemical states.
N-Graphene Nanowalls Via Plasma-Assisted Nitrogen Incorporation and Substitution
Authors: Santhosh Neelakandan M , Filipič Gregor , Kovacevic Eva , Berndt Johannes , Tatarova Elena Stefanova , Cvelbar Uros
Published: July 2021

The electronic properties of the graphene materials can be tuned by chemical doping either by the adsorption of foreign molecules into the graphene lattice or by substitutional doping. Among the various chemical and physical doping techniques, plasma-assisted surface treatment techniques are considered as a fast approach to fabricate nitrogen-incorporated graphene with different nitrogen bonding configurations. However, it is still a great challenge to build nitrogen incorporated graphene with controlled nitrogen concentrations and desired nitrogen configurations. Several studies explained the influence of structural defects in graphene for incorporating N-atoms, which has been formulated by DFT theories. However, there is a lack of experimental evidence to bridge the DFT theories for explaining the influence of structural defects for nitrogen incorporation in graphene. Herein, we report a systematic study on the effect of different nitrogen-containing gaseous plasma post-treatment on vertically oriented graphene nanowalls (CNWs) to fabricate N-CNWs with incorporated and substituted nitrogen. A low-pressure inductively coupled radio-frequency plasma is used as the plasma system with ammonia and nitrogen gases as the reactive gases. The structural and morphological analysis describes a remarkable difference in the plasma surface interaction, nitrogen concentration, and nitrogen configurations in CNWs by using different nitrogen-containing plasma. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy studies confirming the formation of structural defects in the graphene lattice during the plasma treatment. Additionally, the absorption spectra obtained from NEXAFS indicates the presence of different nitrogen configurations in the nitrogen incorporated CNWs. Electrical conductivity measurements revealed that the conductivity of the nitrogen incorporated graphene is strongly influenced by the concentration and different configurations of C-N bonding. These findings indicate that the plasma post-treatment can be used as an effective approach for the synthesis of nitrogen incorporated graphene with controlled concentration and specific configuration of incorporated nitrogen for application-oriented properties.
Machine-Learning Based Transport Property Analytics in Porous Electrodes
Authors: Chatterjee Debanjali , Vishnugopi Bairav Sabarish , Mukherjee Partha P.
Published: July 2021

The electrochemical performance of lithium-ion batteries strongly relies upon the composition and microstructure of the porous electrodes. An electrochemically-coupled set of transport processes underlie the composite electrodes depending on the microstructural arrangement of its constituent material phases. However, the intrinsically stochastic, anisotropic and heterogeneous nature of these porous electrodes makes the characterization of their effective transport properties quite complex. In this work, we examine the use of machine learning as a viable route for fast and accurate abstraction of effective electrode properties, e.g. the tortuosity and effective electronic conductivity of exemplar electrode microstructures based on three-dimensional X-ray tomography images. The proposed computational framework can be generally extended to characterize various modes of transport resistances in porous media.
Identification and Quantification of Aging Modes with Deep Learning Models
Authors: Kim Sangwook , Yi Zonggen , Tanim Tanvir R. , Dufek Eric J.
Published: July 2021

Identifying the dominating aging modes and mechanisms uniquely with higher confidence using early life-cycle data is a significant scientific challenge. In general, lithium-ion batteries experience different aging modes depending on use conditions—e.g., loss of lithium inventory and loss of active material in both electrodes, loss of power capability, etc.—due to different relevant aging mechanisms. The existing body of research almost exclusively uses extended-calendar or cycling-life data along with different post-testing to identify and quantify different dominating aging modes and mechanisms. Early identification of battery aging modes/mechanisms will enable accurate forecasting of battery state-of-health along with the root cause and shorten the design and testing cycle for new battery chemistries and cell designs for emerging applications.

In this presentation, we present a deep learning (DL) modeling framework to enable early identification and quantification of dominating cell aging modes using battery incremental capacity (IC) information at different aging states (Figure 1). The DL model utilizes coin cell data with altered offset and N:P ratio simulating different aging conditions to train and construct two categories of DL models, serving two consecutive steps in the hierarchical learning framework: (i) a classification model to identify the dominating aging modes, e.g. LLI + LAMPE or LLI + LAMNE, (ii) a regression model to quantify the percentages for dominating aging modes, e.g., percentages of LLI and LAM. The deep learning models are built using a 1-D convolutional neural network structure.

The deep learning model’s performance is verified with experimental Gr/NMC pouch cells data with different loadings and utilization conditions. It is demonstrated that the classification model can identify dominating aging modes successfully for current experimental validation sets within 50 cycles, and the quantification model can further determine their percentages of LLI and LAM under aging modes.

Figure 1
(Invited) Calorimetry of Cell Failure in Multiple Formats and Capacity
Authors: Lamb Joshua , Torres-Castro Loraine
Published: July 2021

Accelerating Rate Calorimetry (ARC) has previously been used to evaluate differences observed in various active materials with a typical comparison shown in the figure below. This evaluation is usually performed on small cells of roughly the same capacity (~1 AH) to allow for an easy comparison of active materials as they are developed. However, this and similar calorimetry methods present a means to perform more quantitative measurements of the heat generated and kinetics of thermal runaway. Sandia National Laboratories has performed testing on cells in the 10s of amp hours and analyzed the thermal runaway behavior of these cells.

This work uses accelerating rate calorimetry to evaluate the impact of cell chemistry, state of charge, cell capacity, and ultimately cell energy density on the total energy release and peak heating rates observed during thermal runaway of Li-ion batteries. This work seeks to better understand how applicable small cell data is to understand the thermal runaway behavior of large cells as well as determine if thermal runaway behaviors can be more generally tied to aspects of lithium-ion cells such as total stored energy and specific energy. We have found a strong linear correlation between the total enthalpy of the thermal runaway process and the stored energy of the cell, apparently independent of cell size and state of charge. We have also shown that peak heating rates and peak temperatures reached during thermal runaway events are more closely tied to specific energy, increasing exponentially in the case of peak heating rates.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Figure 1
Heat Generation in Lithium Iron Phosphate/Graphite Batteries: Simulation with Validation through Isothermal and Adiabatic Calorimetric Measurements
Authors: Schimpe Michael , Gillich Elisabeth Irene , Santhanagopalan Shriram , Saxon Aron , Jossen Andreas
Published: July 2021

This work evaluates the heat generation characteristics of a cylindrical lithium iron phosphate/graphite battery. Two experimental approaches are used: Heat flow measurements in an isothermal calorimeter and temperature measurement-based heat generation rate measurements in a quasi-adiabatic Accelerating Rate Calorimeter (ARC).

The experimental results are compared to simulation results of an equivalent circuit model featuring a single resistance, voltage hysteresis representation, and reversible heat generation through entropy representation. The thermal model parameters are adapted to the respective experimental setups.

Results visualize the specific use-cases of the experimental approaches. Isothermal calorimeter measurements enable a strict control of temperature for the battery, however, smooth the higher dynamics of the battery heat transfer due to the thermal mass of the setup. The high rate of heat transfer to ambient enables an evaluation of specific operating temperatures as well as long-duration tests, e.g., full cycles or dynamic current profiles.

Instead, quasi-adiabatic measurements vary strongly in temperature during the operation but provide highly-dynamic information about heat generation rates. The rapid rise in temperature approaches safety limits and thus only low current, charge or discharge tests are possible, with a following rest period required.

Simulation results are discussed with a focus on the heat generation rate and the heat transfer to ambient rate. While in general good agreements between simulation and experiment is achieved, specific differences reveal improvement potential for the model as well as for its parametrization.

References

M. Keyser, A. Pesaran, Q. Li, S. Santhanagopalan, K. Smith, E. Wood, S. Ahmed, I. Bloom, E. Dufek and M. Shirk, Journal of Power Sources, 367, 228 (2017).

A. Pesaran, M. Keyser, G. Kim, S. Santhanagopalan and K. Smith, Tools for designing thermal management of batteries in electric drive vehicles (presentation), in, National Renewable Energy Lab.(NREL), Golden, CO (United States) (2013).

M. Schimpe, M. Naumann, N. Truong, H. C. Hesse, S. Santhanagopalan, A. Saxon and A. Jossen, Applied Energy, 210, 211 (2018).

A. R. Saxon, Battery Extreme Fast Charge: A Thermal Prospective, in, National Renewable Energy Lab.(NREL), Golden, CO (United States) (2019).

J. Geder, R. Arunachala, S. Jairam and A. Jossen, in 2015 IEEE Green Energy and Systems Conference (IGESC), p. 24 (2015).
(Invited) Directionality of Thermal Gradients in Li-Ion Batteries Dictates Diverging Failure Modes
Authors: Love Corey T. , Carter Rachel E. , Kingston Todd A. , Atkinson III Robert , Parmananda Mukul , Dubarry Matthieu , Fear Conner , Mukherjee Partha P.
Published: July 2021

The Li-ion battery revolutionized energy storage with its high energy density coupled with impressive reversibility; however, negative electrode reactivity and low positive electrode conductivity facilitate unpredictable capacity fade and catastrophic failure (e.g., thermal runaway). The origin of these degradation modes often remains elusive, making them difficult to replicate for safety and lifetime assessment. This work demonstrates that mild (±2 °C) interelectrode thermal gradients at conventionally safe operating conditions (35 °C and C/5 rate) facilitate rapid degradation, identifying both a risk case and a technique for accelerated aging. Further, the directionality of the thermal gradient dictates which electrode experiences degradation, thereby adding a layer of understanding and control. Our findings will impact the Li-ion field at all scales from local electrochemistry to pack design. The design of thermal management strategies should consider the risks for, and minimize, interelectrode thermal gradients, which, in part, are dependent on active material, form factor, and operational conditions. Interelectrode thermal gradients can be utilized as an accelerated aging strategy or technique for safety assessment, given they serve as a trigger for rapid capacity loss.
(Invited) The Mutual Roles of the Plasma and Liquid in Plasma Electrolysis
Authors: Go David
Published: July 2021

Plasma electrolysis can be roughly described as replacing one of the solid electrodes in a conventional electrolytic cell with a plasma (i.e., gas discharge) such that charge transfer oxidation or reduction reactions occur at a plasma-liquid interface rather than a solid-liquid interface. One of the most promising aspects of these systems is the chemistry induced in the liquid by the plasma, ranging from the reduction of metal cations to produce colloidal nanoparticles to the oxidation of organic compounds for water remediation. However, because the plasma itself is a dynamic medium, the liquid also has an impact on plasma properties and behavior. Ultimately, the physics and chemistry of both the plasma and liquid are tightly coupled and mutually dependent, and unraveling these interactions is important for understanding, designing, and optimizing these systems. This talk will overview the efforts of our team to understand these roles using a variety of experimental measurements, theory, and simulations. Topics will include the in situ detection of the solvated electron injected by a plasma, the efficiency of those electrons in driving chemistry, and a recent theoretical description of plasma self-organization on the liquid surface.
Kinetic Mechanisms Driving Ag+ Reduction and Nanoparticle Synthesis By Atmospheric Pressure Plasma-Driven Solution Electrochemistry
Authors: Exarhos Stephen , Yue Yuanfu , Bruggeman Peter
Published: July 2021

Plasma-driven solution electrochemistry (PDSE) is an emerging technique for processing novel materials among other applications. PDSE has a key advantage over conventional electrolysis in that it can inject electrons into solutions without the presence of a metal surface. Current applications of PDSE are limited because of prohibitive energy efficiencies and a lack of understanding in the underpinning processes, including the importance of plasma-injected species relative to solution-generated species and kinetics-limiting effects. Recent studies have shown that there are several factors that differ between PDSE and conventional electrolysis, meaning new and expanded models are required to precisely describe PDSE. For example, it is commonly assumed that reduction processes in PDSE are predominantly mediated by solvated electrons – as is the case in conventional electrolysis – while the influence of ions, photons, and radicals present in the system are considered to be negligible or not studied. However, recent work studying plasma-liquid interactions from ours and other groups have indicated that, while solvated electrons are certainly significant in PDSE reduction processes, they are not wholly deterministic of the plasma-induced solution phase kinetics. The work presented is an investigation of reduction kinetics of Ag+ using a quasi-continuous flow pulsed-DC atmospheric pressure PDSE system. We focus on the evolution of the solution phase from pre- to post-plasma exposure. We present experimental results that, although gathered from indirect characterization techniques, allow us to infer information about the kinetics mediating Ag+ reduction and ensuing nanoparticle nucleation and growth. Specifically, we seek to deconvolve UV-photon induced reactions, neutral hydrogen-driven reduction, and neutral hydroxide-driven processes, in addition to solvated electron-driven reduction. A refined understanding of PDSE in a model system like Ag will enable access to more complex, more efficient, and higher yield chemical processes in PDSE systems that are not possible with conventional electrochemistry.

This work was supported by the Army Research Office under Grant Number W911NF-20-1-0105.
(Invited) Facile Manufacturing of Colloidal Nanocrystals to Macroscale Film
Authors: Ha Don-Hyung
Published: July 2021

Design of nanostructured films using colloidal nanocrystals (NCs) has received significant attention because NC films can be utilized for a wide range of applications. Conventional solution processes with colloidal NCs such as spin-coating, dip coating, and spray coating have been generally utilized for the solution-based NC film fabrication. However, these conventional film fabrication methods have limitations of mechanical robustness, film uniformity, and production of thick film. Electrophoretic deposition (EPD) technique is an alternative deposition process to overcome the limitation of traditional solution-based film fabrication methods. EPD can provide enhanced electrical conductivity, a dense film, high mechanical stability, and controllability of the film morphology. Owing to these advantages, NC films fabricated using EPD have been studied for various applications and found to exhibit better performance compared to those obtained via traditional solution processes. This EPD technique can easily manipulates the movement of charged particles in a suspension under an electric field using a wide range of parameters such as electrical condition, suspension parameters, and distance between electrodes. Through the control of such key parameters, we demonstrated that the deposition mechanism can be switched leading to different morphologies of the NC film. In addition, the migration of NCs toward electrodes was observed through in-situ techniques.
(Invited) 3D Epitaxially-Connected Quantum Dot Superlattices: Formation, Structure, and Transport
Authors: Law Matt
Published: July 2021

Colloidal quantum dots (QDs) that are epitaxially interconnected (necked or partially fused) to form highly-ordered, highly-coupled superlattices are an exciting new class of materials for optoelectronics. These epitaxially-fused QD superlattices (epi-SLs), which are typically made by self-assembly and ligand exchange on a liquid surface followed by stamp transfer to a solid substrate (the Langmuir-Schaefer technique), promise to combine the size-tunable photophysics and solution processability of QDs with delocalized, bulk-like carrier transport.

In this talk, I describe recent progress in making epi-SLs of sufficient spatial and energetic order to delocalize carriers into mini-bands. I discuss the fabrication of high-quality 3D epi-SL films, along with the determination of their structure (the complete superlattice unit cell) and physical formation pathway from the parent oleate-capped SL using a combination of X-ray scattering and correlative electron microscopy and diffraction of single SL grains. The oleate- to epi-SL phase transition occurs by nearly-pure translation of the QDs with minimal rotational motion, resulting in a rhombohedrally-distorted simple cubic epi-SL with fusion along the PbSe {100} facets. This simple translational phase transition is facilitated by the rhombohedral distortion of the initial oleate-capped SL and results in >5 μm epi-SL grains free of linear or planar defects. While large epi-SL grains are useful, several types of intra-grain structural defects conspire to reduce order within the grains and localize charge carriers. Quantitative characterization of these intra-grain defects and a better understanding of the molecular processes involved in epi-SL formation have enabled fabrication improvements that enhance intra-grain order and overall film uniformity. Measurements probing mini-band formation and the impact of SL surface chemistry on charge transport will be discussed.
(Invited) Crystal Phase Engineering of Cesium Lead Iodide By Nanoconfinement
Authors: Fafarman Aaron
Published: July 2021

Nanoscale dimensional reduction leads to perturbed electronic structure, a foundational concept in the study of quantum dots. In this work, we extend this concept to consider how nanoscale dimensionality perturbs the crystal phase diagram of a solid. We apply this to the phase behavior of cesium lead iodide, a material that possesses favorable optoelectronic properties in its perovskite crystal polymorph at high temperature, and exhibits an undesirable crystal phase at room temperature. We develop and test the hypothesis that for solids such as cesium lead iodide that simultaneously exhibit both predominantly covalent bonding (Pb—I) and predominantly ionic bonding (Cs—I), low-density, high-symmetry phases can be favored by restricting crystal dimensions below 100 nm. This is based on a model in which short-range, orbital-orbital repulsive forces, which favor low-density and high-symmetry phases, are in competition with long-range electrostatic forces, which favor high-density. The electrostatic forces, being long-range in nature, are more diminished by truncating the crystal. Experimentally, we show that the phase sequence can be inverted and the equilibrium shifted by as much as 250 ºC through various nanostructuring approaches, including colloidal nanocrystal co-assembly and crystallization within nanoporous scaffolds. Ultimately, we seek to develop a phase diagram in which temperature and size are the independent variables.
(Keynote) All Roads Lead to Rome: Paths of Heat and Charge Transport in Hybrid Polymer-Nanowire Systems
Authors: Urban Jeffrey
Published: July 2021

In this talk, we present research that aims to identify the specific pathways of heat and charge transport in complex hybrid polymer-nanowire thermoelectric systems. These materials have demonstrated remarkable performance due to interfacial charge transport dynamics that have proven difficult to untangle. Here I present the work of a few recent papers to disaggregate the role of the organic and inorganic layer in the transport of charge and heat, as well as the mechanism that causes an enhancement in thermoelectric performance. We also assess the role of specific features of the polymer and nanowire themselves, and how those contribute to transport. We do this at both the single nanowire level, and also at the film level, enabling meaningful comparisons and conclusions. Through combining thermoelectric property measurements using a custom-built suspended microbridge setup for single nanowires, the Kang-Snyder charge transport model as well as gate modulated electrical conductivity measurements, we conclude that the thin organic PEDOT:PSS shell is the predominant channel for charge carrier transport in this hybrid material, and the large electrical conductivity is attributed to the highly ordered PEDOT chains on the Te nanowire surface brought about by a templating effect. We also present complementary research on charge transport characteristics of modified PEDOT:PSS derivatives as well. This talk will summarize the work of our 4 most recent manuscripts from the last few months.
(Invited) Synthesis and Surface Engineering of III-V Semiconductor Quantum Dots for Infrared Optoelectronic Applications
Authors: Oh Nuri
Published: July 2021

Colloidal quantum dots (QDs) have widely been considered as emerging candidates for solution-processable optoelectronic devices. Especially, QDs that are optically active in NIR and SWIR spectral windows, offer a great promise for infrared emitters, infrared photodetectors, photovoltaics, and biological imaging applications. It is thus essential to develop high-quality infrared QDs without the use of heavy metals such as cadmium, lead, or mercury. Among various semiconducting materials, III-V compound semiconductors show great potential in practical optoelectronic applications not only due to their wide tunability in the infrared region, but also due to their excellent optical and electronic properties. However, the synthesis of III-V semiconductor-based QDs has been limited by the lack of understanding about the precursors of group V elements such as P, As and Sb. In this presentation, we would like to discuss about the pnictogen precursors to synthesize various III-V QDs and also the surface properties of the resultant QDs. By controlling the reaction process with the pnictogen precursors, we achieve size and stoichiometry-tunable III-V QDs including InP, InAs, InSb and alloy QDs. Based on structural, analytical, optical, and electrical characterization of the QDs, we study the effects of surface treatments on their optoelectronic properties. We demonstrate that III-V QD thin films are promising candidate materials for infrared optoelectronic devices.

Figure 1
Cation Effect on Anion Exchange in CsPbX3 (X = Cl, Br, I) Perovskite Nanocrystals
Authors: Ahn Junhyuk , Lee Yong Min , Kim Woosik , Oh Soong Ju
Published: July 2021

Colloidal quantum dot and nanocrystals have been shown to be promising materials for device applications because of their

unique size-dependent properties and solution processability. We present general methods to engineer the

electronic, optoelectronic, electromechanical, and electrothermal properties of nanocrystals through their

surface and interface engineering. Unconventional materials design and strategy are introduced to

fabricate semiconducting devices such as field effect transistors, photodetectors, solar cells, and wearable

sensors including temperature sensors, strain sensors, and pressure sensors. This technique provides a

pathway for designing low cost, high performance, and multifunctional electronic skins or wearable

devices.
Safe Synthesis of InP Quantum Dots for Biological Applications
Authors: Chandrasiri Hashini Bhagya , Kim Eun Byoel , Snee Preston
Published: July 2021

Semiconductor nanocrystals (also known as quantum dots) have been extensively studied because of their unique optical properties which makes them promising candidates for bio imaging and bio sensing. II-VI semiconductor quantum dots are commonly used in biomedical applications because of their near unit quantum yields and narrow emission profiles. Despite these advantages, II-VI semiconductor nanocrystals contain toxic metals. As a result, III-V semiconductor nanocrystals such as InP are promising replacements for cadmium-based semiconductor nanocrystals. However, the synthesis of bright InP quantum dots with narrow size distribution is challenging mainly due to the use of overly reactive phosphorus precursors like tris(trimethylsilyl) phosphine (TMS)3P. This reagent is also highly flammable. We employed less pyrophoric sterically encumbered tris(triethylsilyl) phosphine and tris(tributylsilyl) phosphine for the synthesis and observed that quantum yield and the emission color saturation (fwhm) of InP nanocrystals are improved compared to those prepared with (TMS)3P, but not up to the levels realized with CdSe. HF treatment is often employed as a post-synthetic treatment to improve the optical properties of quantum dots. We demonstrate that ammonium bifluoride is a safer alternative to extremely hazardous HF. Ammonium bifluoride etched InP core dots were further passivated to create InP/ZnSeS core-shell quantum dots that were later water-solubilized and functionalized for biological applications.

Figure 1
(Invited) Corrosion Effects on Electrochemically Deposited Lithium Metal Electrode
Authors: Bao Wurigumula , Lu Bingyu , Cheng Diyi , Li Weikang , Ceja Miguel , Fang Chengcheng , Meng Shirley
Published: July 2021

The lithium metal anode is essential for high energy density rechargeable battery due to its high specific capacity (3,860 mAh·g-1, or 2,061 mAh·cm-3)and low electrochemical potential (–3.04 V versus the standard hydrogen electrode). Although extensive studies have been performed to overcome dendrite growth and low coulombic efficiency problems associated with the practical use of lithium metal anode, there is a lack of comprehensive understanding of the storage properties and shelf life of lithium metal batteries, where chemical/electrochemical corrosion plays a critical role. We introduced the TGC (titration gas chromatography) method to quantify the corrosion rate of electrochemically deposited Li in liquid electrolyte system. It is demonstrated that lithium metal is mainly suffered from chemical corrosion by the liquid electrolyte instead of by electrochemical corrosion, that is, the direct charge transfer between lithium-electrolyte interphase. Besides, the corrosion rate of electrochemically deposited lithium in different electrolytes is further studied, where different electrolytes are found to introduce different corrosion rates. By taking into account the influence of different electrolytes on the SEI and Lithium morphology, we differentiate these two aspects, and the results in (1) The corrosion rate is mainly affected by the surface area of deposited lithium. The larger the surface area that the lithium has, the faster the corrosion rate will be; (2) The SEI components formed by different electrolytes on deposited lithium are similar, and different electrolytes will lead to the similar corrosion rate when the surface area is the same. Our findings provide valuable insights on the corrosion problem of electrodeposited lithium, where the surface area of deposited lithium turns out to dominate its storage properties.
Electrophoretic Deposition of Aluminum Particles and Control of the Coating Microstructure
Authors: Wagner Julien , Ansart Florence , Taberna Pierre-Louis , Gani Léa , Knittel Stéphane
Published: July 2021

Electrophoretic deposition (EPD) is an efficient process for the elaboration of homogeneous thickness and tunable microstructure coating on conductive substrates [1]. EPD displays several advantages such as a low operating cost, a relatively simple equipment and the ability to plate uniformly onto complex shape parts [1]. Among all studies on electrophoretic deposition, metallic particles are widely less investigated than ceramic ones. However metallic materials offer interesting properties (optics, catalysis, etc.). The use of alcoholic media is widely advantageous for electrophoretic deposition process because a significant voltage range can be investigated while avoiding water electrolysis and bubbles formation. Moreover, as some metals present high reactivity towards aqueous media, the choice of alcohols as dispersing media looks appropriated. Electrophoretic deposition of an aluminum powder was performed in different alcoholic media: ethanol and propan-2-ol. The nature of the dispersing medium appears to strongly influence the process deposition. Direct EPD from pure ethanol suspension is not convenient [2] whereas deposition from propan-2-ol medium leads to an homogenous coating (Figure 1). Nevertheless, addition of ionic species into the ethanol suspension allows an increase of the number of aluminum particles deposited. The addition of these species also lead the formation of homogenous thickness coating up to 100 µm. The influence of the key parameters (relative to the suspension and the electrophoretic process) has been investigated in relationship to the coatings thickness and the microstructure.

Keywords: electrophoretic deposition, aluminum, coating, microstructure.

Figure 1: FIB-prepared cross-section of Al coating deposited under 10 V.cm-1 during 10 min from propan-2-ol suspension.

References:

1. L. Besra and M. Liu, “A review on fundamentals and applications of electrophoretic deposition (EPD),” Prog. Mater. Sci., vol. 52, no. 1, pp. 1–61, 2007.

2. K. S. Yang, Z. Jiang, and J. S. Chung, “Electrophoretically Al-coated wire mesh and its application for catalytic oxidation of 1,2-dichlorobenzene,” Surf. Coatings Technol., vol. 168, no. 2–3, pp. 103–110, 2003.

Figure 1
Electrochemical Conversion of Lignin Model Compounds
Authors: Staser John , Harrington Peter , Chen Zewei , Ghahremani Raziyeh
Published: July 2021

Electrochemical conversion of biomass, including lignin, is one possible means of generating industrial chemicals like aromatic compounds from a renewable raw material. The complexity of much of this raw material, however, makes controlling the major product classes difficult. To complicate matters, in many cases the primary reaction mechanism is not clear. Indeed, there may be several competing reaction pathways. It may be that during early-stage research efforts, clearer information can be achieved by investigating electrochemical conversion of smaller, more simple model compounds that share some common features with the larger biomass polymer. In this study, we investigate electrochemical conversion of lignin model compounds on non-precious metal electrocatalysts with subsequent analysis using techniques including GC-MS. We investigate possible electrochemical oxidation mechanisms, including whether the dominant mechanism may be driven by hydroxyl radical mediation. The focus of this talk will be on the electrochemical process and analysis of the products leading to identification of the most likely reaction pathways.
Enhanced CO2 Conversion per Pass with Packed Bed Membraneless Electrolyzers
Authors: Pang Xueqi , Sekhar Aditya , Esposito Daniel V.
Published: July 2021

The electrochemical reduction of carbon dioxide (CO2) has been investigated to be a promising pathway to convert a fraction of the excess CO2 emissions into value-added fuels and chemicals using renewable electricity. CO2 electrolyzers with high selectivity and industrially relevant current density have been demonstrated in recent years. However, a major challenge is to achieve a high conversion per pass. Especially at high current densities, the local alkalinity created by CO2 reduction reaction (CO2RR) results in CO2 losses due to the formation of carbonates, which limits the CO2 conversion per pass. Here, we present novel and potentially low-cost packed bed membraneless electrolyzers (PBMEs) to achieve high CO2 conversion per pass. In particular, PBMEs are ideally suited for maintaining favorable pH so that carbonate formation can be minimized. Basic operating principles have also been modeled.
Revealing Active Sites in Atomically Dispersed Metal Catalysts on N-Doped Carbon for Electrocatalytic CO2 Reduction By Operando XAS
Authors: Li Tao , Fang Lingzhe
Published: July 2021

Abstract

Single-atom catalysts (SACs) represent a promising class of low-cost materials with high catalytic activity and 100% atom-utilization efficiency, widely applied in energy conversion fields.[1-2] Benefit from tunable coordination environment, the uniformly dispersed SACs on diverse supports exhibit satisfied catalytic ability. More importantly, different from the multiple crystal facets of nanomaterials can serve as active sites. There is only one active site consisting of the single metal atom and coordinated atoms in SACs, thereby improving the selectivity of products some catalytic reactions. Moreover, atomically dispersed metal catalysts exist in cations, which exhibit better stability than traditional nanoparticulated counterparts.[3] However, SACs are susceptible to undergo restructuring during the reactions because of high surface free energy. Therefore, exploring the active sites of SACs through in-situ characterization techniques plays a critical role in studying the reaction mechanism and guiding the design of optimum SACs.

As a synchrotron-based element-specific technique, X-ray absorption spectroscopy (XAS) is influential in studying the probed element's structural information. X-ray absorption near edge structure (XANES) spectra reflect the electronic structure, while extended X-ray absorption fine structure (EXAFS) spectra provide local atomic structural information such as coordination number, bond length, and structural disorder. Thus, in-situ XAS is promising and widely used for monitoring electronic structure and atomic configuration changes of SACs during real-time working conditions. We have prepared Ni, Cu single atoms on nitrogen-doped carbon (NiCu@NC-900), which exhibit improved catalytic ability compared with Ni SACs and Cu SACs. Nuclear magnetic resonance results show only ethanol as a liquid product during CO2 reduction reaction (CO2RR). To explore the origin of improved catalytic performance of SACs toward CO2RR, we are going to monitor changes of SACs under open-circuit voltage (OCV) and working conditions by Operando XAS.

[1] Li, Z., Ji, S., Liu, Y., Cao, X., Tian, S., Chen, Y., Niu, Z., Li, Y. Chem. Rev. 120, 2 (2020).

[2] Ji, S., Chen, Y., Wang, X., Zhang, Z., Wang, D., Li, Y. Chem. Rev. 120, 21 (2020).

[3] Speck, F. D., Paul, M. T. Y., Ruiz-Zepeda, F., Gatalo, M., Kim, H., Kwon, H. C., Mayrhofer, K. J. J., Choi, M., Choi, C. H., Hodnik, N., Cherevko, S. J. Am. Chem. Soc. 142, 36 (2020).
Electrochemical Animal Waste Remediation: Multi-Factor Effect Analyses on Nutrient Reduction and Struvite Deposition
Authors: Ojoawo Babatunde IBRAHIM , Pindine Garrett , Trembly Jason , Daramola Damilola
Published: July 2021

Proper usage of land to meet the global growing demand in the area of food supply, safe environment and good quality of water bodies requires the delivery of fertilizer for specific nutrient needs. Most of the farmers directly use animal waste as a fertilizer on the farm, which causes eutrophication to the water bodies due to excess nutrient accumulation.

A lot of research has been conducted on the use of chemical means to recover the amount of phosphorus and nitrogen in wastewater as struvite (MgNH4PO46H2O), however this project explores the use of an electrochemical method for struvite deposition using a (graphite) anode and a stainless steel cathode in an undivided cell. Therefore, this electrochemical technique is relatively simple and cheap.

In a prior study, the efficacy of this technology was examined with key operating parameters affecting struvite deposition identified as temperature, turbulence, applied potential and competing ion (Ca2+) concentration [1]. In addition, a thermodynamic simulation was developed to further investigate the impact of Ca2+ in animal waste on the technology’s performance [2]. However, the effect of parameter interactions on electrochemical nutrients reduction is unknown. In this new study, multi-factor analyses will be conducted based on the combination of the previously identified operating parameters and N:P ratio, to characterize optimal nutrient reduction and resource recovery from animal waste.

References

[1] Z. Belarbi and J. P. Trembly, “Electrochemical Processing to Capture Phosphorus from Simulated Concentrated Animal Feeding Operations Waste,” J. Electrochem. Soc., vol. 165, no. 13, pp. E685–E693, Jan. 2018, doi: 10.1149/2.0891813jes.

[2] Z. Belarbi, D. Daramola and J. P. Trembly, “Bench-Scale Demonstration and Thermodynamic Simulations of Electrochemical Nutrient Reduction in Wastewater via Recovery as Struvite,” J. Electrochem. Soc., vol. 167, no. 4, Nov. 2020, DOI: 10.1149/1945-7111/abc58f
A Comparison of Transition Metal Oxide Ordered Macroporous Materials Used in Battery Electrodes
Authors: McNulty David , O'Hanlon Sally , Carroll Aoife , Lonergan Alex , O'Dwyer Colm
Published: July 2021

This talk will summarize recent results of ordered macroporous (inverse opal) materials made from a range of transition metal oxides when used as Li-ion battery electrodes. The basic methodology for macroporous material formation will be presented for electrodes fabricated with macroporous ordered materials included TiO2, SnO2, GeO2, V2O5, their mixtures and other compounds.

The talk will compare the basic lithiation response in these porous materials in Li-in battery half cells and detail the electrochemical response of each oxide and porous structure as a function of specific current (rate) and cycle life. Several of these materials offer surprisingly good electrochemical stability during long (>5000 cycles in the case of TiO2) cycle life, in a binder and conductive additive-free electrode formulation. We also summarize limits of some macroporous oxide materials at very high charge and discharge rates when used in Li-ion batteries and compare the influence of phase and structure on reversible lithiation.

Related work and References

O'Hanon, D. McNulty, R. Tian, J. Coleman, and C. O'Dwyer, High Charge and Discharge Rate Limitations in Ordered Macroporous Li-ion Battery Materials, J. Electrochem. Soc. 167, 140532 (2020).

McNulty, H. Geaney, Q. Ramasse, and C. O'Dwyer, Long Cycle Life, Highly Ordered SnO2/GeO2 Nanocomposite Inverse Opal Anode Materials for Li‐Ion Batteries, Adv. Funct. Mater., 2005073 (2020).

McNulty, H. Geaney, D. Buckley, and C. O'Dwyer, High Capacity Binder-free Nanocrystalline GeO2 Inverse Opal Anodes for Li-ion Batteries with Long Cycle Life and Stable Cell Voltage, Nano Energy 43, 11 (2018).

McNulty, E. Carroll, and C. O'Dwyer, Rutile TiO2 Inverse Opal Anodes for Li-ion Batteries with Long Cycle Life, High-rate Capability and High Structural Stability, Adv. Energy Mater. 7, 1602291 (2017).

McNulty, A. Lonergan, S. O'Hanlon, and C. O'Dwyer, 3D open-worked inverse opal TiO2 and GeO2 materials for long life, high capacity Li-ion battery anodes, Solid State Ionics 314, 195 (2018).

Lonergan, D. McNulty, and C. O'Dwyer, Tetrahedral framework of inverse opal photonic crystals defines the optical response and photonic band gap, J. Appl. Phys. 124, 095106 (2018).

O'Hanlon, D. McNulty, and C. O'Dwyer, The influence of colloidal opal template and substrate type on 3D macroporous single and binary vanadium oxide inverse opal electrodeposition, J. Electrochem. Soc. 164, D111 (2017).

O'Dwyer, Colour-Coded Batteries – Inverse Opal Materials Circuitry for Enhanced Electrochemical Energy Storage and Optically Encoded Diagnostics, Adv. Mater. 28, 5681 (2016).