bluuebunny/crossref_metadata_2025 huggingface dataset:
Supramolecular Architecturing of Quantum Box Arrays from Functionalized Porphyrins and Exploring Their Quantum States
Authors: Ahsan Aisha , Mousavi Fatemeh S. , Popova Olha , Nijs Thomas , Nowakowska Sylwia K. , Baljozovic Milos , Pasti Igor A. , Morari Cristian , Iarinca Luiza , Hill Jonathan P. , Liu Shi Xia , Decurtins Silvio , Thilgen Carlo , Gade Lutz , Lobo Checa Jorge , Diederich Francois , Stoehr Meike , Jung Thomas A.
Published: July 2021

Our research is based on the analysis of structure-function correlations for a broad spectrum of functionalized porphyrins and phthalocyanines in their propensity to create increasingly complex and functional on surface architectures. [1] Thereby we use porphyrin and phthalocyanine functionalization and synthesis, ‘by design’, or ‘on-surface-supramolecular chemistry’ to create structures with specific physical properties towards e.g. future quantum devices.

By using a fluoro-bi-phenyl functionalized porphyrin to create a stable, porous organic network, we manufacture arrays of identical quantum boxes. These boxes contain a specific quantum well state arising from the confinement of the electronic (Shockley) surface state within the pores. We show that the electronic quantum box state as well as the interbox coupling can be modified locally by adsorbates, e.g. C60, interacting with the barrier. In view of the wealth of available and differently acting adsorbates, this approach allows for the engineering of quantum states in on-surface network architectures. Thus, by their dance on the nose of the ‘devil’ [3], porphyrins and phthalocyanines justify the emergence of ‘on-surface supramolecular physics’ as reflected by ongoing and future research work.

Fig. 1) Adsorbate-induced modification of the confining barriers in a quantum box array formed by a functionalized fluoro-bi-phenyl porphyrin on Ag(111). (Taken from [2])

[1] N. Wintjes et al. Two-dimensional phase behavior of a bimolecular porphyrin system at the solid-vacuum interface, J. Am. Chem. Soc. 2010, 132, 21, 7306-7311; N. Wintjes et al., Supramolecular synthons on surfaces: Controlling dimensionality and periodicity of tetraarylporphyrin assemblies by the interplay of cyano and alkoxy substituents Chem. Eur. J. 2008, 14, 5794.

[2] S. Nowakowska et al., Adsorbate-induced modification of the confining barriers in a quantum box array, ACS Nano 2018, 12, 768.

[3] W. Pauli “God made the bulk; surfaces were invented by the devil.” Quoted, e.g. in the Preface of A. Zangwill, Physics at Surfaces, Cambridge University Press, 1988. ISBN 978-0-521-34752-5

Figure 1
Charge Stabilization in Axially Linked Donor – Aluminum(III) Porphyrin – Fullerene Reaction Center Models
Authors: Zarrabi Niloofar , Seetharaman Sairaman , Chaudhuri Subhajyoti , Holzer Noah , Batista Victor , van der Est Art , D'Souza Francis , Poddutoori Prashanth
Published: July 2021

In supramolecular reaction center models, the lifetime of the charge-separated state depends on many factors. However, little attention has been paid to the redox potential of the species that lie between the donor and acceptor in the final charge-separated state. Recently, we reported a series of self-assembled aluminum porphyrin-based triads that provide a unique opportunity to study the influence of the porphyrin redox potential independently of other factors. The triads, Donor-AlPorFn-C60, were constructed by linking the fullerene (C60) and Donor to the aluminum(III) porphyrin. The porphyrin (AlPor, AlPorF3, or AlPorF5) redox potentials are tuned by the substitution of phenyl (Ph), 3,4,5-trifluorophenyl (PhF3), or 2,3,4,5,6-pentafluorophenyl (PhF5) groups in its meso positions. The C60 and Donor (BTMPA) units are bound axially to opposite faces of the porphyrin plane via covalent and coordination bonds, respectively. Excitation of all of the triads results in sequential electron transfer that generates the identical final charge-separated state, BTMPA•+-AlPorFn-Ph-C60
•−, which lies energetically 1.50 eV above the ground state. Although the radical pair is identical in all of the triads, remarkably, the lifetime of the BTMPA•+-AlPorFn-Ph-C60
•− radical pair was found to be very different in each of them. I will discuss some of these systems in terms of their design principles and photoinduced properties.

Figure 1
Conformational Design of Enzyme-like Porphyrin Binding Pockets for Catalysis and Sensing
Authors: Senge Mathias O.
Published: July 2021

Porphyrins have long been recognized as sensors for various analytes. However, this involves mostly metalloporphyrins and there are still limitations with regard to discrimination and sensitivity. Here we illustrate that metal-free metal-free (‘free base’) porphyrins can be re-engineered via conformational design to make the core N-H units accessible for interaction with substrates or analytes. This allows to utilize metal-free porphyrin free bases as organocatalysts. Highly conjugated porphyrin macrocyclic systems offer spectrophotometric sensitivity towards geometrical and/or electronic changes and thus, utilizing the porphyrin core for selective detection of substrates in solution offers significant potential for applications. As a proof-of-concept we describe how a combination of macrocycle distortion in conjunction with suitable functional groups in the porphyrin periphery allowed the design of the binding pocket in an enzyme-like fashion and facilitated the highly selective detection of the pyrophosphate anion in a switchable sensor system.
Unraveling Coordination Features of Hemihexaphyrazines - New Approach to Perspective Materials for Nanoelectronics
Authors: Islyaikin Mikhail K. , Koifman Oskar I. , Konarev Dmitri V. , Torres Tomas
Published: July 2021

Hemihexaphyrazins are macrocycles containing three thiadiazole and three pyrrolecontaining subunits unified by an alternating fashion via six aza-bridges to form an expanded coordination cavity with 27-membered inner macroring bearing 9 nitrogen atoms. Due to such unusual structure to compare with porphyrins and phthalocyanines, hemihexaphyrazins have an enormous potential in coordination chemistry. It was established that they are able to hold 3 atoms of transition metals within inner cavity. Recently a clear evidence of such complexes formation was obtained by scanning tunneling microscopy (STM) [1]. Early using STM, unprecedented off-centered complexation motif of metal free hemihexaphyrazin (H3Hph) with dysprosium on Au(111) surface has been detected [2].

Moreover, it was showed that due to presence of 9 nitrogen atoms within coordination cavity, H3Hph in reduced state can act as an aza-crown ether to form a new type of double-decker complex [3]. Partial charge transfer and uniform distribution of the charge over two macrocycles make these as promising building blocks for designing compounds with potential conducting and magnetic properties.

Acknowledgement: this work was partially supported by Russian Foundation of Basic Research (project 19-03-00888) and Russian Science Foundation (project N 17-13-01215).

Literature

Bacilla Ana C. C., Okada Yusuke, Yoshimoto Soichiro, Islyaikin Mikhail K., Koifman Oskar I.; Kobayashi Nagao. Triangular Expanded Hemiporphyrazines: Electronic Structures and Nanoscale Characterization of Their Adlayers on Au(111). Bulletin of the Chemical Society of Japan. BCSJ. 2021, Vol.94, No.1, pp. 34 – 43. DOI: 10.1246/bcsj.20200188.

Borja Cirera, Olga Trukhina, Jonas Björk, Giovanni Bottari, Jonathan Rodriguez-Fernandez, Alberto Martín-Jiménez, Mikhail K Islyaikin, Roberto Otero, José M. Gallego, Rodolfo Miranda, Tomas Torres, and David Ecija. Long-range orientational self-assembly, spatially-controlled deprotonation and off-centered metallation of an expanded porphyrin. J. Am. Chem. Soc., 2017, 139 (40), pp 14129–14136. DOI: 10.1021/jacs.7b06406.

Dmitri Konarev, Salavat S. Khasanov, Mikhail K. Islyaikin, Akihiro Otsuka, Hideki Yamochi, Hiroshi Kitagawa, Rimma N. Lyubovskaya, Evgenii N. Ivanov, Oskar I. Koifman, Yuriy A. Zhabanov. Double-Decker Paramagnetic {(K)(H3Hhp)2}2- Radical Dianions Comprising Two [30]Trithia-2,3,5,10,12,13,15,20,22,23,25,30-Dodecaazahexaphyrins and a Potassium Ion. Chemistry – An Asian Journal. 2020, 15, 61 – 65. DOI: 10.1002/asia.201901518.
The Balance between Conductivity and Electro-/Photo-Catalytic Performance of Guest-Incorporated Metal-Organic Frameworks
Authors: Duan Jiaxin , Kim Mansu , Hupp Joseph
Published: July 2021

Porphyrin plays an important role in being a chromophore in photocatalysis and it was also investigated for years as a competent candidate in electrocatalysis when metals are loaded. In addition to being used as individual molecules, porphyrin can also be assembled into corners and cages. Moreover, with the development of Metal-Organic Frameworks (MOFs), a type of hybrid materials containing metal clusters and organic linkers, porphyrin has become one of the key building blocks when we consider making MOFs a good electro-/photo-catalyst. However, most MOFs possess insulating metal clusters as nodes which lead to the insulating nature of the whole framework. The insulating nature of MOFs hinders sufficient electro-/photo- catalytic performance. The key advantage of MOFs, on the other hand, is that they offer high loading of active sites, large cavities for great accessibility, and rigid frameworks can, if constructed properly, prevent active moieties from sintering. Herein, we evaluated the competition between conductivity and the electro-/photo- catalytic performance of porphyrin containing MOFs. The conductivity of these porphyrin containing MOFs was enhanced by guest incorporation. After modification, the electrical conductivity and electro-/photo- catalytic performance were measured separately. Surprisingly, these MOFs do not require a significant conductivity to generate a competitive electro-/photo-catalytic performance.
Quantifying Reversible Nitrogenous Ligand Binding to Co(II) Porphyrin Receptors at the Solution/Solid Interface and in Solution
Authors: Mazur Ursula , Hipps K. W.
Published: July 2021

We present a quantitative study comparing the binding of 4-methoxypyridine, MeOPy, ligand to Co(II)octaethylporphyrin, CoOEP, at the phenyloctane/HOPG interface and in toluene solution. Scanning tunneling microscopy (STM) was used to monitor ligand binding to the porphyrin receptors adsorbed on graphite with single-molecule resolution. Electronic spectroscopy was employed for examining this process in fluid solution. The on-surface coordination reaction was completely reversible and followed a simple Langmuir adsorption isotherm. Ligand affinities (or ΔG) for the binding processes in the two different chemical environments were determined from the respective equilibrium constants. The free energy value of -13.0±0.3 kJ/mol for the ligation reaction of MeOPy to CoOEP at the solution/HOPG interface is less negative than the ΔG for cobalt porphyrin complexed to the ligand in solution, -16.8±0.2 kJ/mole. This result indicates that the MeOPy-CoOEP complex is more stable in solution than on the surface. Additional thermodynamic values for the formation of the surface ligated species (ΔHc = -50 kJ/mol and ΔSc = -120 J/mol) were extracted from temperature dependent STM measurements. Density functional computational methods were also employed to explore the energetics of both the solution and surface reactions. At high concentrations of MeOPy the monolayer was observed to be stripped from the surface. Computational results indicate that this is not because of a reduction in adsorption energy of the MeOPy-CoOEP complex. Nearest neighbor analysis of the MeOPy-CoOEP in the STM images revealed positive cooperative ligand binding behavior. Our studies bring new insights to the general principles of affinity and cooperativity in the ligand-receptor interactions at the solution/solid interface. Future applications of STM will pave the way for new strategies designing highly functional multisite receptor systems for sensing, catalysis, and pharmacological applications.
Single-Particle Hyperspectral Imaging Reveals Kinetics of Silver Ion Leaching from Alloy Nanoparticles
Authors: Al-Zubeidi Alexander , Stein Frederic , Flatebo Charlotte , Rehbock Christoph , Hosseini Jebeli Seyyed Ali , Landes Christy F. , Barcikowski Stephan , Link Stephan
Published: July 2021

Gold-silver alloy nanoparticles are have attracted attention for multiple applications, including heterogeneous catalysis, optical sensing, and antimicrobial properties. The inert element gold can act as a stabilizer for silver to prevent particle corrosion to slow down silver ion leaching and increase the durability of plasmonic alloy nanoparticles in sensing or catalytic applications. On the other hand, intentional release of antimicrobial silver ions has been used to fight infections caused by bacteria. Understanding silver ion leaching from gold-silver alloy nanoparticles is a therefore prerequisite to designing alloy nanoparticles with either unintended or intended corrosion. However, little is known about the mechanism and kinetics of silver ion leaching from bimetallic gold-silver nanoparticles and how it is correlated with particle size and silver content, especially not on a single-particle level. To characterize the kinetics of silver ion release from gold-silver alloy nanoparticles, we employed a combination of electron microscopy and single-particle hyperspectral imaging with an acquisition speed fast enough to capture silver ion leaching for a statistically relevant number of individual nanoparticles. Our studies confirmed a reduction in corrosion rate due to the alloying with as little as 10-20 mole% gold. Single-particle leaching profiles revealed two leaching stages, with a large heterogeneity in rate constants. We modelled the initial leaching stage with a shrinking-particle model with a rate constant that exponentially depends on the silver mole fraction. The second, slower leaching stage is controlled by diffusion of silver atoms through a passivating gold rich lattice, and a change in electrochemical potential of the nanoparticle. Individual nanoparticles with similar sizes and compositions exhibited completely different dealloying yields. Most nanoparticles released silver completely, but 25% of them appeared to arrest corrosion. Calculations of average size together with SEM revealed that nanoparticles became slightly porous. Our findings suggest that alloy nanoparticles, produced by scalable laser ablation in liquid, together with kinetic studies of silver ion leaching, provide an approach to selectively design the durability or anti-microbial bioactivity of alloy nanoparticles.

Figure 1
A Real Time Electrochemical Analysis of Co-Sputtered (Co-Cr) and (Co-Cr-Mo) Alloy Thin Film Libraries in Ringer’s Solution at 37 oc
Authors: Lone Shaukat Ali , Mardare Cezarina Cela , Mardare Andrei Ionut , Hassel Achim Walter
Published: July 2021

Cobalt-based alloys are used as total hip replacement prostheses due to their exceptional tribocorrosion properties in the human physiological environment[1]. Due to continuous mechanical and corrosive conditions, the dissolution of Cr and Co in the body fluid is unavoidable. These metallic particles and ions can cause cancer and gene mutation in the body, therefore their leaching should be diminished by proper passivation[2].

In this work, two combinatorial thin film libraries namely a binary Co-Cr and a ternary Co-Cr-Mo were prepared by means of co-sputtering. Both libraries were characterized by state of the art high resolution scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chromium content for binary Co-Cr library varied from 14-40 at.% (balanced Co) while for ternary Co-Cr-Mo library a compositional spread of Co (46-79 at.%), Cr (17-48 at.%) and Mo (3-11 at.%) was obtained. In both libraries roundish spike shaped grains were revealed at high cobalt content which gradually changed to refined and compact grains with the increment of Cr. Similarly, molybdenum (>-7 at.%) brought additional grain refinement. Furthermore, weak, and broad XRD peaks of rt HCP and ht FCC pure Co were disclosed at nearly all compositions. No intermetallic phase was determined in either library.

The real time electrochemical screening and corrosion stability were accomplished by a in house-built flow type scanning droplet cell microscope (FT-SDCM) in conjunction with an inductively couple plasma optical emission spectroscope (ICP-OES). Various electrochemical techniques i.e. open circuit potential, linear sweep voltammetry and Tafel extrapolation were utilized. No significant passive behavior was obtained for the alloys containing the Co content higher than (68-70 at.%) irrespective of Cr and Mo concentration. However, further increment in the Cr content significantly improved the alloy nobility and restricted the active to passive dissolution. The addition of Mo improved the transpassive dissolution. A graphical model was developed on the basis of this study and a composition range of (7-10) at.% Mo and (36-48) at.% Cr (complementary Co) is recommended as likely candidate for biomedical use.

References

[1] A. Aherwar, A. K. Singh, A. Patnaik, Cobalt Based Alloy: A Better Choice Biomaterial for Hip Implants, Trends Biomater. Artif. Organs, 30, 50–55, (2016); doi: 10.13140.2.1.2501.5284.

[2] E. N. Codaro, P. Melnikov, I. Ramires, A. C. Guastaldi, Corrosion Behavior of a Cobalt Chromium-Molybdenum Alloy, Russ. J. Electrochem., 36, pp. 1263-1267, (2000); doi: 10.1007/02757531
Electrodeposition of Zinc-Nickel Alloys from Ethylene Glycol for Corrosion Protection
Authors: Bernasconi Roberto , Firtin Fatma Godze , Kahyaoglu Buse , Nobili Luca , Magagnin Luca
Published: July 2021

Zn rich ZnNi alloys electrodeposition have recently attracted the attention of researchers due to their interesting corrosion properties [1]. In particular, alloys containing Ni in the 15 - 25 % range find application in a number of industrial fields, like automotive and constructions. ZnNi is normally electrodeposited from aqueous solutions, in which plating takes place following a typical anomalous mechanism [2]. In the last few years, however, new deposition approaches have been attempted to improve ZnNi plating performances. Specifically, III generation deep eutectic solvents comprising choline chloride have been tested [3].

The present work investigates the use of non-aqueous ethylene glycol based electrolytes for the deposition of Zn rich ZnNi alloys. The use of ethylene glycol as solvent introduces many advantages with respect to aqueous solutions: low oxygen contamination, high deposits purity and no pH dependance [4]. ZnNi codeposition was studied employing cyclic voltammetry and layers were deposited under potentiostatic control. Deposition potential was varied and its influence on final composition and morphology was determined. Addition of an additive (NH4Cl) to enhance surface morphology was attempted as well [3]. Phase composition was investigated using XRD to determine the possible presence of a metastable γ-ZnNi phase, which has already been observed in the case of ZnNi plated from alkaline aqueous solution [5]. Finally, corrosion behavior of layers obtained from ethylene glycol was assessed and compared with equivalent coatings deposited from commercial aqueous solutions.

[1] M. Gavrila et al.; Surface and Coatings Technology, 123 (2-3), 164-172 (2000)

[2] G. Roventi et al.; Journal of Applied Electrochemistry 30 (2), 173–179 (2000)

[3] S Fashu et al.; Transactions of Nonferrous Metals Society of China 25 (6), 2054-2064 (2015)

[4] G. Panzeri et al.; Electrochimica Acta 271 (1), 576-581 (2018)

[5] S. Ieffa et al.; Transactions of the IMF 94, 321-324 (2014)
First Principles, Explicit Interface Studies of Oxygen Vacancyand Chloride in Al2O3 Films on Metal Surfaces for Metal Corrosion Applications
Authors: Leung Kevin
Published: July 2021

Pitting corrosion is a much-studied and technologically relvant subject. However, the fundamental mechanisms responsible the breakdown of the passivating oxide layer are still subjects of debate. Chloride anions are known to accelerate corrosion; relevant hypotheses include Cl insertion into positively charged oxygen vacancies in the oxide film, and Cl adsorption on passivating oxide surfaces -- substituting for OH-. In this work, we conduct large scale first principles modeling of explicit metal/Al2O3 interfaces to investigate the energetics and electronic structure associated with these hypotheses in connection to atmospheric aluminum corrosion. The explicit interface models allow electron transfer that mimics electrochemical events, and the establishment of the relation between atomic structures at different interfaces and the electronic band alignment. For multiple model interfaces, we find that doubly charged oxygen vacancies, which are key ingredients of the point defect model (PDM) often used to analyze corrosion data, can only occur in the presence of a potential gradient that raises the voltage. Cl- insertion into oxide films can be energetically favorable in some oxygen vacancy sites, depending on the voltage. Cl- substitution of surface hydroxyl groups is energetically unfavorable. We also discuss the challenges associated with explicit DFT modeling of these complex interfaces.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and 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. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the document do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Figure 1
An Approach to Mechano-Electrochemistry on a Stainless-Steel Alloy
Authors: Hangarter Carlos M , Anderson Rachel , Policastro Steven
Published: July 2021

Galvanic couples play an important role in atmospheric corrosion, and tools enabling greater understanding of their mechanisms can better inform the development of corrosion models. This work employs UNS S13800 in a simulated atmospheric corrosion environment to explore the influence of mechanical stress on cathodic reaction kinetics. The electrochemical response of this material was measured, using electrochemical impedance spectroscopy and polarization experiments, while mechanically loaded and in the unstressed state. All samples were exposed to thin electrolyte films with elevated chloride concentrations that had equilibrated to the chamber’s temperature and relative humidity. The first set of samples was cathodically polarized to different static potentials while elastic load cycles were performed at different rates. The second set of samples were similarly polarized but the applies stresses induce plastic deformation in the samples while the load cycling was performed. The time-varying ORR rates were used to monitor the mechanical influence on electrochemical kinetics.
Effect of Applied Pressure on the Ceria Chemical Mechanical Planarization
Authors: Kwak Donggeon , Oh Seungjujn , Yun Junho , Kim Juhwan , Kim Taesung
Published: July 2021

Ceria abrasive is widely used in the Inter layer dielectric (ILD) Chemical mechanical planarization (CMP) due to its high removal rate and high selectivity ability. Despite the relatively low hardness of the ceria, Ce-O-Si bonding between silicon oxide surface and ceria abrasive enables high removal rate of silicon oxide CMP. Therefore, it is important to investigate the Ce-O-Si bonding for further study of the post CMP cleaning as well as ceria CMP. In this study, the effect of the applied pressure on the ceria CMP was investigated. Dipping and polishing process was conducted to confirm the surface change with applied pressure. The Fourier-transform infrared spectroscopy was measured to compare between dipped wafer and polished wafer. Fig 1 showed FT-IR spectra of each samples. Bare wafer and dipped wafer show similar spectra. Meanwhile, polished wafer shows different spectra in the range of 1000-1200 cm-1 and 800-900cm-1 which were associate with the Si-O-SI and Si-O bonding. The intensity of the both peak decreased due to the Ce-O-Si bonding.

Zeta potential is a key factor for adsorption behavior of the ceria CMP. Generally, ceria particle can adsorb on the silicon oxide surface due to electrostatic attraction with opposite zeta potential. however, adsorption phenomenon was different as function of the applied pressure. The applied pressure plays an important role in the adsorption behavior of ceria as well as the zeta potential. This research suggests the importance of the applied pressure for the ceria CMP process.

Figure 1. FTIR spectra of the silicon oxide wafer in region of 600-1600 cm-1

Figure 1
Investigation of CMP Performance According to Pad Surface Condition and Abrasive Types
Authors: Jeon Sanghcuk , Lee Jungryul , Hong Seokjun , Kim Kyunghwun , Park Kihong , Kim Chang min , Kim Taesung
Published: July 2021

Chemical mechanical planarization (CMP) is a planarization technique that combines mechanical and chemical factor for enhanced polishing and ﬁnishing. CMP process reduces the surface roughness to meet the requirements of semiconductors. The characteristics of CMP, such as material removal rate (RR), thickness uniformity and surface quality, are determined by various mechanical and chemical factors. CMP has many consumables. Slurry, conditioner, and pad are typically used in CMP process. These consumables’ interaction is very important in CMP process. The reason why, the other can affect each other. These factors are known to signiﬁcantly affect the results of CMP. During the process time, the lack of conditioner will block the pore and glazing on the pad surface. The longer process time, the lower pad cut rate is occurred because of poor conditioner performance [1]. And then pad glazing is occurred.

When the pad glazing occurred, RR is changed [2]. At this point, the RR has different value according to abrasive. The number of particles that can act on the wafer depends on the pad surface changed. This affects the local pressure acting on the wafer. As the amount of abrasive acting on the wafer increases, the local pressure on the wafer is decreased. As briefly think about the situation, reduction of local pressure should result in decreasing removal rate. However, when the pad glazing situation, the RR has difference phenomenon according to abrasive types. Normally, Fig.1 (a) shows RR using ceria abrasive. It has higher RR after pad glazing. Fig.1 (b) shows RR using silica abrasive. It has lower RR after pad glazing.

In this research, the difference in RR according to abrasive types generated during pad glazing was investigated. Based on these phenomena, I present the optimum pad land area each abrasive.

Reference

[1] C. Shin, H. Qin, S. Hong, S. Jeon, A. Kulkarni, and T. Kim, Journal of Mechanical Science and Technology, pp. 5659-5665, (2016).

[2] H. Kim et al., Wear, pp. 93-98, (2017).

Figure 1
Development of NMC811@ZrO2 Core-Shell By Mechano-Fusion Process and Annealing Process for Next-Generation Lithium-Ion Batteries
Authors: Tubtimkuna Suchakree , Sawangphruk Montree
Published: July 2021

The application of advanced Ni-rich cathode materials in commercial lithium-ion batteries is increasing attention due to its high capacity. The Ni-rich lithium nickel manganese cobalt oxide (LiNi0.8Mn0.1Co0.1O2, NMC811) is a cathode material for the state-of-the-art lithium-ion battery due to its high specific energy, long cycle life, safety issue, and cost-effective. However, the challenges of NMC811 such as cation mixing, micro-crack, metal dissolution, and parasitic reaction urgently need to be overcome(1, 2). Both synergistic effects of the surface protection layer of NMC@ZrO2 core–shell structure using a solvent-free mechano-fusion process. Also, the doping concept of Zr4+ into the Li slab of its structure by the annealing process is of interest in this work. These two strategies can enhance the performance and life cycle of NMC811 batteries by addressing all of the issues of NMC811.

REFERENCES

T. Li, X.-Z. Yuan, L. Zhang, D. Song, K. Shi and C. Bock, Electrochemical Energy Reviews, 3, 43 (2020).

W. Li, Journal of The Electrochemical Society, 167, 090514 (2020).

Figure 1
Calendar Vs. Cycle Aging of Lithium-Ion Cells with Silicon Anode
Authors: Luo Mei , Rodrigues Marco-Tulio , Abraham Daniel P. , Shaw Leon
Published: July 2021

Silicon has been investigated for decades, as an alternative to the graphite used in lithium-ion battery anodes, because of its high theoretical capacity. However, the large volume change of Si during electrochemical cycling (cycle-aging) deteriorates the solid electrolyte interphase (SEI) layer on the particles, resulting in increased electrolyte reduction reactions and associated capacity decay. Capacity fade is also observed in cells that are not cycled but simply held at voltage for extended periods of time (calendar-aging). [1]

Here we report the calendar and cycle-aging behavior of cells with a Si anode that is paired with a NMC532 cathode (Figure 1). The tests were conducted in coin cells and in cells with a reference electrode (prepared by in-situ lithiation of a 25 mm Cu wire). This reference electrode allowed us to determine changes in the individual electrode profiles during aging and to examine impedance changes that were monitored via hybrid pulse power characterization (HPPC) tests. [2]

Our various experiments have revealed the following: (i) capacity-fade is greater during cycle-aging than during calendar-aging; (ii) the capacity fade is associated with shifts in both positive and negative electrode potentials; (iii) parasitic currents are observed during the calendar-life hold, which indicate ongoing electrolyte reduction reactions at the silicon electrode; (iv)both electrodes contribute to the significant impedance rise observed during cell aging.

To further examine sources of the observed performance degradation we conducted experiments with cells with the Si paired with LiFePO4. These data, along with the probable mechanisms of cell aging, will also be discussed during the presentation.

References

Kalaga et al., Acta 2018, 280, 221-228.

Klett et al., Electrochem. Soc. 163 (2016) p. A875.

Acknowledgments: M.L. acknowledges the generous grants from the U.S. National Science Foundation with the award numbers of CMMI-1660572 and IIP-1918991 that enabled her research at Argonne National Laboratory. The electrodes and electrolytes used in this study are from Argonne’s Cell Analysis, Modeling and Prototyping (CAMP) Facility. We are grateful to Andrew Jansen, Bryant Polzin, and Steve Trask for their assistance during this study.

Figure 1
Comparison of Failure Mechanisms in Lithium Manganese Oxide and Lithium Nickel Manganese Oxide Spinel Cathodes
Authors: Jayawardana Mestiyage Dona Chamithri , Lucht Brett L.
Published: July 2021

LiNi0.5Mn1.5O4 (LNMO), with an operating voltage of 4.9 V vs Li/Li+ and a theoretical capacity of 147 mAhg-1 and LiMn2O4 (LMO), with an operating voltage of 4.1 V vs Li/Li+ and a theoretical capacity of 133 mAhg-1 are both highly attractive cathode material for secondary lithium ion batteries (LIB) owing to their low material cost, and excellent rate capability due to their spinel structure. Over the last two decades, much research effort has been focused on gaining a fundamental understanding of the failure mechanisms of these two electrodes. Dissolution and deposition of manganese was long thought to be the principle failure mechanism of LMO electrodes while for LNMO, because of its high operating voltage, electrolyte decomposition and concurrent degradative reactions at the electrode/electrolyte interfaces were thought to be the main culprit. In this study we have systematically investigated the failure mechanisms of LMO & LNMO electrodes. Full cells were built using graphite as the negative electrode and 1.2 M LiPF6 in EC: EMC, 3:7 as the electrolyte and were cycled at room temperature and at elevated temperature. Several quantitative and qualitative analysis techniques were conducted to investigate the correlation between capacity loss and Mn ion deposition, acidic species generation, solid electrolyte interphase (SEI) degradation, impedance growth as these cells cycled at different temperatures.
Characterization of Sn@TiO2 Anode Material for Li-Ion Battery Application
Authors: WANG Yun Hui , Shen Yu-Min , Chang Chia-Chin
Published: July 2021

In this work, various phases of nanorod TiO2 were fabricated by hydrothermal process. Different crystalline phases of TiO2 nanowires will be analyzed by electrochemical analysis (CV, LSV, C-rate, charge and discharge, and EIS test) to investigate the influence of Li+ diffusion rate on specific capacitance. The in-situ XRD structure for charging and discharging will be carried out to explore the diffusion and structural behavior of Li+ in TiO2 was explored its fast charging, high capacitance and high safety characteristics, which will be a fundamental research of Sn modified on TiO2 nanowire. Transmission electron microscope image showed a range of 20 to 80 nm length TiO2 nanorods was success synthesized, and the XRD indicated the phase were rutile, anatase and rutile/anatase mixed by controlling the chelating agents (citric acid). The specific capacity of TiO2 nanorod was 120 mAh/g which the Columbic efficiency was ~ 99% under 0.1 C. A morphology of Sn@TiO2 was investigated as nano-capsule. The results are supposed to clarify the key factors of the fast charge, high specific capacitance and safety. It is expected that the Li+ ion influence on structure changes during the charge and discharge process by implementing this research. The fast charging, high specific capacity and high safety mechanism will be established as an index for material application and commercial products.

Keywords: TiO2 anode materials, Sn@TiO2 anode materials, Li-ion battery, In-operando XRD
Importance of Interlayers on Li Solid-State Batteries Using Ceramic Electrolytes
Authors: Fung Kuan-Zong , Tsai Shu-Yi , Du Jia , Chen Hong Chun
Published: July 2021

Recently, all solid-state Li ion batteries have received great attention due to its better safety feature. Among several types of inorganic solid electrolyte, Garnet-structured Li6.5La3Zr1.5Ta0.5O12
(LLZTO) is found to exhibit high ionic conductivity with adequate stability especially directly connecting to pure lithium foil as anode. However, it is difficult for inorganic solid electrolyte to have full contact with lithium anode, the high interface polarization and poor wetting ability between solid electrolyte and anode has been a major concern in all state Li ion batteries. Therefore, interface engineering between solid electrolyte and electrodes has been shown to exhibit low interface polarization. In this study, the objective is to investigate the effects of metallic interlayer on reduction of the surface polarization between LLZTO and Li using thin film gold (Au) interlayer. The surface impedance has reduced to less 200ohm/cm2which was demonstrated by EIS measurement and Li stripping/plating tests using a symmetrical cell. The battery behavior was observed by LiCoO2/Ta-LLZO/Li battery, which discharge capacity > 125mAh/g for the first cycle.
(Invited) Grain Boundaries and Dislocations in Layered Cathodes
Authors: Xu Zhengrui , Lin Feng
Published: July 2021

Crystallographic defects exist in many redox active energy materials, e.g., battery and catalyst materials, which significantly alter their chemical properties for energy storage and conversion. In this presentation, we will address how these defects, e.g., grain boundaries and geometrically necessary dislocations, govern the charge distribution and battery performance of layered oxide cathodes.

Architecting grain crystallographic orientation can modulate charge distribution and chemomechanical properties for enhancing the performance of polycrystalline battery materials. However, probing the interplay between charge distribution, grain crystallographic orientation, and performance remains a daunting challenge. Herein, we elucidate the spatially resolved charge distribution in lithium layered oxides with different grain crystallographic arrangements and establish a model to quantify their charge distributions. While the holistic “surface-to-bulk” charge distribution prevails in polycrystalline particles, the crystallographic orientation-guided redox reaction governs the charge distribution in the local charged nanodomains. Compared to the randomly oriented grains, the radially aligned grains exhibit a lower cell polarization and higher capacity retention upon battery cycling. The radially aligned grains create less tortuous lithium ion pathways, thus improving the charge homogeneity as statistically quantified from over 20 million nanodomains in polycrystalline particles. This study provides an improved understanding of the charge distribution and chemomechanical properties of polycrystalline battery materials.

Crystallographic defects, such as geometrically necessary dislocations, are reported to influence the redox reactions in battery particles through single-particle, multimodal, in situ synchrotron measurements. Through Laue X-ray microdiffraction, many crystallographic defects are spatially identified and statistically quantified from a large quantity of diffraction patterns in many layered oxide particles, including geometrically necessary dislocations, tilt boundaries, and mixed defects. The in situ and ex situ measurements, combining microdiffraction and X-ray spectroscopic imaging, reveal that LiCoO2 particles with a higher concentration of geometrically necessary dislocations provide deeper charging reactions, indicating that dislocations may facilitate redox reactions in layered oxides during initial charging. The present study illustrates that a precise control of crystallographic defects and their distribution can potentially promote and homogenize redox reactions in battery materials.
Operando mapping for Kinetic Effects on Single Particles of LiNi0.80Co0.15Al0.05O2 at Different C-Rates
Authors: Li Chao , Cabana Jordi
Published: July 2021

LiNi0.80Co0.15Al0.05O2 (NCA) is one of the most promising cathode material for Lithium ion batteries which has relatively high theoretical specific capacity. Achieving a thorough understanding of reaction processes at the single particle level will help to close the gap between practical and theoretical capacity of NCA. AMPIX cells with diluted NCA cathode (20% active material) were studied using operando μX-Ray transmission. The single NCA particles were located successfully. The electrochemical performance of single particles were studied at different points in the lifetime of the battery as well as at different charge/discharge rates (C/20, C/8, C/3). The XRD patterns sets of each particle were compared as well as the unit cell parameters of each individual particles. The rates of (de)lithiation of each particle were quantified for analysis of inter-particle dynamics in this work. The kinetic effect on the homogeneity of each particles at different rates was also analyzed by phase analysis in this work.
Mechanism of Effect of Roughness on Dendrite Growth
Authors: Gao Liting ting , Guo Zhan sheng
Published: July 2021

Lithium metal is an ideal anode material for high energy density rechargeable batteries. However, the repeated use of the battery leads to the increase of the roughness of the electrode surface, which aggravates the growth of harmful dendrites. The harmful dendrites will lead to short circuit and cause safety hazard. In this paper, the aspects of overpotential, curvature and pit shape were studied to understand the mechanism of effect of roughness on dendrite growth. The results show that the growth of needle like and dendritic dendrites is mainly due to the local disturbance of surface current density. The disturbance of surface current density is caused by the relative asymmetry of overpotential, curvature and deposition rate. High overpotential and small curvature will aggravate the disturbance of local current density, resulting in asymmetric dendrite formation. We also found lithium deposition in the pit, which is consistent with the published experimental results. However, whether dendrite can grow in the pit depends on the size of the pit. These results provide meaningful information for optimizing battery performance and improving safety.
Understanding the Fast Charging Effect on Anode and Electrolyte in Li Ion Battery
Authors: Yang Zhenzhen , Trask Stephen E. , Bloom Ira
Published: July 2021

In recent years, fast charging is a key enabler of mainstream adoption of battery-based electric vehicles into the transportation sector. Charging at high rates has been shown to accelerate degradation, causing the capacity, life and safety of batteries to deteriorate. Currently, the issues of fast charge residing inside the battery include cathode particle cracking, loss of active material, electrolyte-electrode side reactions, Li plating at the anode and electrolyte decomposition. In spite of all available information, there are no systematic studies in the open literature regarding the above issues caused by fast charging. Herein, we investigated the effects of charge rate in coin cells containing NMC532/1506-T graphite. The cells were cycled at room temperature using high charge rates of 1-, 2-, 4-, and 8-C and discharged at the 1-C rate for 50 cycles. Li plating and SEI formation on the anodes as a function of charging rates was examined by SEM and XPS. The amount of lithium plating and SEI composition were found to be correlated with charging rates. The concentrations of the transition metal dissolution on charge rate was studied by ICP-MS. The results show dependence of the concentrations of the TMs on charge rate is complex. The degraded electrolytes in the cells were collected and analyzed by HPLC-MS. Three decomposition products were identified in the organic electrolyte, regardless of the charge rates. The relative concentrations of these organics did not display sensitivity to charge rate. These findings in this work provide new understanding of the failure mechanisms of batteries during fast charging.
Capturing Material Heterogeneities Effects on the Electrochemical Impedance of Li(Ni1-x-yMnxCoy)O2-Based Cathodes through 4D-Resolved Physical Simulations
Authors: Shodiev Abbos , N. Primo Emiliano , Chouchane Mehdi , Lombardo Teo , Ngandjong Alain C. , A. Franco Alejandro
Published: July 2021

Electrochemical impedance spectroscopy (EIS) is a widely used technique for the characterization of Lithium Ion Battery (LIB) porous electrodes, and to extract their tortuosity factors in particular, using transmission line models supported on homogenizations and oversimplifications of the actual electrode texture Here we use our a 4D (3D in space + time) physical model to simulate EIS carried out on NMC porous cathodes, derived from the simulation of their manufacturing process, in symmetric cells.[1]

The calculations of EIS spectra on the manufacturing model-calculated porous electrodes (in a symmetric cell configuration) were done in a diluted electrolyte regime by explicit consideration of the spatial location of active material, carbon and binder domain (CBD) and pore phases, with distinctive physics for each of them.2 The calculated impedance responses are compared with our experimental results arising from NMC-based cathodes prepared in a similar way. The possibility to tune the physical properties of each phase in our 4D model allowed us to identify the different contributions to the EI spectra shapes. We found that for NMC-based cathodes there is a complex interplay between the solid and ionic conductivities, which affects the characteristic times at which each region of the porous electrode is accessed as a function of the frequency. Furthermore, we found that electrode inhomogeneities related to the spatial CBD location results in highly inhomogeneous impedance behaviors. We observe that these effects strongly depend on the electrode formulation and other manufacturing parameters, such as the electrode calendering. We believe that our 4D model constitutes a powerful tool to assess EI spectra beyond the limitations of traditional transmission line models.

Shodiev, Abbos, Primo, Emiliano N., Chouchane, Mehdi, Lombardo, Teo, Ngandjong, Alain C., Rucci, Alexis & Franco, Alejandro A. 4D-resolved physical model for Electrochemical Impedance Spectroscopy of Li(Ni1-x-yMnxCoy)O2-based cathodes in symmetric cells: Consequences in tortuosity calculations. J. Power Sources (2020). 227871 doi:10.1016/j.jpowsour.2020.227871

Chouchane, Mehdi, Rucci, Alexis, Lombardo, Teo, Ngandjong, Alain C. & Franco, Alejandro A. Lithium ion battery electrodes predicted from manufacturing simulations : Assessing the impact of the carbon-binder spatial location on the electrochemical performance. J. Power Sources (2019). 444, 227285

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(Invited) Pattern Generation from the Irradiation Induced Crosslinking of Organic Monolayers Coupled with an Area Selective Deposition
Authors: Wojtecki Rudy
Published: July 2021

Responsive materials drive the controllable generation of nanoscale patterns and have broad reaching applications in computation and sensing, for instance. As technology platforms broaden and the demand for ever smaller critical dimensions increase chemical control over surfaces then become more important. Current approaches to nanoscale fabrication largely rely on subtractive processes, which often alters the chemical composition of a surface (such as oxidation) or damage materials by amorphizing the sidewalls of an otherwise crystalline thin film, from processes like reactive ion etching or solution-based chemical etches. As miniaturization reaches single nanometer regimes, surfaces and interfaces become increasingly significant and can dominate the performance of a final device. An alternative patterning strategy where a film is ‘added’ in a selected area, versus ‘subtracted’ presents a method to grow components of a device without damage to surfaces or interfaces. This approach is demonstrated with a responsive monolayer, where a pattern-wise exposure crosslinks the film to produce a selective barrier guiding film formation and growth of a metal oxide in a subsequent deposition step. This combination of a responsive monolayer with an area selective deposition was used to achieve high fidelity patterns with features as small as 50 nm.
Isotropic Atomic Layer Etching in High Aspect Ratio Structures
Authors: Fischer Andreas , Lemaire Paul , Routzahn Aaron , Lill Thorsten
Published: July 2021

Isotropic Atomic Layer Etching can be used to remove materials such as high-k oxides or certain metals from high aspect ratio (HAR) structures from sidewalls and even non-line-of-site locations where access via reactive ion etching would be challenging or impossible. Those locations could be sites below the shelves in 3D-NAND stacks or around wires in GAA structures.

The etch rate per cycle of Thermal Isotropic ALE should in principle be insensitive to aspect ratio and line-of-sight accessibility if both reaction steps are fully saturated. Deviations from the ideal behavior have been reported previously for Al2O3 ALE with alternating HF and DMAC cycles [1]. Without mitigation, this behavior would ultimately lead to performance differences in devices located at the bottom of the structure compared to those at the top.

In this work we present a method to counteract the unwanted depth dependence of the etch rate when etching HfO2 with the HF/DMAC ligand exchange ALE process. To mitigate the depth dependence, we explored the use of operating the ALE process at ultra-high pressures up to 5 Torr and over a wide temperature range. We found that under these conditions, the modification step has been boosted such that it takes place near its saturation regime so that top-to-bottom etch rate differences could be reduced. We show that high pressure and temperature mostly target the fluorine profile along a structure and removal step times needed to be allowed sufficient time to clear the entire modified layer. We give an example of such application in a 50:1 aspect ratio 3D NAND test structure.