bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking Thermodynamic Changes Due to Cycling and Calendar Ageing of Commercial High-Energy Li-Ion Cells: Effects of Relaxation Periods
Authors: Zulke Alana Aragon , Wojtala Malgorzata , Hoster Harry Ernst , Howey David
Published: December 2020

There is a great need for non-invasive tools that enable improved insight into the underlying causes of battery ageing. In this project we investigate cycling and calendar ageing effects on high energy commercial cylindrical cells (NCA|Si-Gr), by tracking thermodynamic and kinetic aspects by the employment of entropy profiling, differential voltage and incremental capacity analysis (DVA/ICA), and differential thermal voltammetry (DTV). Two groups of three cells from the same batch are being subjected to different ageing scenarios, both at 45°C: group A is under calendar aging at 75 % state of charge - SoC at which we observed the most accelerated calendric aging for these cells - and group B, which is being cycled continuously at the maximum current allowed by the manufacturer. To ensure minimal temperature fluctuations during tests and allow proper comparative DTV, cells were submerged in a high conductivity dielectric fluid bath. We revised Osswald’s approach for entropy profiling [1], and also increased the number of titration steps in entropy profiling to 63, for both charge and discharge. Fig. 1 shows the results for the initial 40-day aging period, comparing ICA and entropy profiles, before and after ageing. In addition to the capacity fade of 2.2 % and 6.2 % for groups A and B respectively (Figure 1a), the loss of sharpness present in the ICA peaks is also present in the entropy curves (features A1-A4 in Fig. 1b). This can be attributed to a more heterogeneous lithium distribution and a change in lithium inventory. To track the reversibility of ageing and the time scales of passive electrode effects [2], both groups of cells will be submitted to rest periods after which entropy, DTV and ICA experiments will be periodically repeated.

References

[1] P.J. Osswald, M. Del Rosario, J. Garche, A. Jossen, H.E. Hoster, Electrochim. Acta 177 (2015) 270–276.

[2]M. Lewerenz, G. Fuchs, L. Becker, D.U. Sauer, J. Energy Storage 18 (2018) 149–159.

Figure 1
Correlating Materials Degradation Trends to Electrochemical Indicators in Systematic Long-Term Cycling of Commercial Li-Ion Batteries
Authors: Wittman Reed M , Fresquez Armando , Langendorf Jill , Ivanov Sergei , Taggart Gretchen , Chalamala Babu R. , Preger Yuliya
Published: December 2020

In order to improve the operation of Li-ion batteries the long-term performance is the subject of much research. Of particular importance is understanding systematic trends in degradation through a broad range of operating conditions. Over the course of the last few years, researchers at Sandia National Labs have conducted a systematic study of battery cycling behavior. In this study, dozens of commercial NCA (LiNixCoyAl1-x-yO2) and NMC (LiNixMnyCo1-x-yO2) cells were cycled to 80% capacity and end of life across a range of temperatures, discharge rates, and depth of discharge windows. Analysis of both in situ electrochemical data and postmortem materials degradation was done.

During cycling, cell resistance (IR), Electrochemical Impedance Spectroscopy (EIS), and differential capacity (dQ/dV) experiments were conducted periodically. The data from these experiments were used to understand the state of health (SoH) of cycling cells, including SEI formation and Li plating, as well as general mass transport and kinetic properties.

X-ray Computed Tomography (X-ray CT) scans completed before cell disassembly showed large scale deformation in the cells’ jelly rolls. For the postmortem analysis cells in pristine condition, 80% capacity, and end of life were disassembled, and their electrodes were analyzed with X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), and Brunauer-Emmett-Teller Isotherms (BET). These techniques analyzed different aspects of the electrodes’ physical and chemical properties, including Li plating, micro-cracking, SEI layer formation, and phase changes in cathode materials. BET and DSC measurements also provided insight into changes in the degree to which aged electrodes undergo thermal runaway events.

Correlation of the postmortem materials analysis with the in situ electrochemical analysis gave an in-depth understanding of the origins of performance fade during cycling. The scale of this electrochemical and materials evaluation fills in gaps in the literature about battery performance and degradation beyond 80% capacity.

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.
Fabrication of High-Aspect Metal Nanostructure Using Anodic Porous Alumina and Its Optical Property
Authors: Kondo Toshiaki , Yanagishita Takashi , Masuda Hideki
Published: December 2020

High-aspect nanostructure, such as a nanohole and a coaxial nanocable, are considered as a powerful candidate for a light waveguide. Especially, a coaxial nanocable can efficiently propagate the incident light because the coaxial nanocable does not have cut-off wavelength as seen in a nanohole. In addition, by reducing the opening size of the coaxial nanocable, the coaxial nanocable can propagate the light to an area less than a wavelength of the incident light beyond the diffraction limit. Therefore, the coaxial nanocable is expected to be applied to fabricate various types of functional optical devices, such as nanoimaging device and high-density optical recording device. However, it is still difficult to fabricate the high-aspect nanostructure with complicated geometrical features such as the coaxial nanocable because of fabrication difficulties. Until now, our group had been reported fabrication process of the high-aspect metal nanostructures using an anodic porous alumina and its optical property [1-3]. Anodic porous alumina has an ordered array of straight nanoholes having high aspect ratio. Due to this unique geometrical character, anodic porous alumina is commonly used as a starting material to fabricate nanostructures having high aspect feature. In our previous work, we reported fabrication of the coaxial nanocables having high aspect ratio using anodic porous alumna [3]. In addition, it was observed that the coaxial nanocable could efficiently propagate the visible light. In the present work, with the aim of improving the performance of the functional devices based on the coaxial nanocable, reduction of opening size of the coaxial nanocable and evaluation of the optical property were demonstrated. This fabrication process is expected to be applied to fabricate various types of functional optical devices requiring the fine coaxial nanocable.

K. Nishio, M. Nakao, A. Yokoo, H. Masuda, Jpn. J. Appl. Phys.,
42, L83 (2003).

T. Kondo, N. Kitagishi, T. Yanagishita, H. Masuda, Appl. Phys. Express, 8, 06200 (2015).

T. Kondo, R. Ichinose, M. Kurosawa, T. Yanagishita, H. Masuda, The 87th ECSJ Spring Meeting, 1C06 (2020).
Study of Imperfections and Hardness of Anodic Oxide Films on AA2024 Based on Ink-Impregnation Method
Authors: Moon Sungmo
Published: December 2020

Various imperfections can be formed in the anodic oxide films on aluminium alloys because of second-phase particles and they affect corrosion resistance and surface hardness of aluminium alloys. In this work, ink-impregnation method was newly employed to observe imperfections in the anodic films on AA2024 and to measure surface hardness of the anodic oxide films with different imperfections. The ink-impregnation allows clear observation of not only the imperfections within the anodic oxide films but also an indentation mark on the oxide film surface. Two different imperfections of black defects and grey defects were found in the anodic oxide films formed on AA2024 in 20% sulphuric acid solution and the surface hardness was dependent on the type, size and density of defects. Large size black defects showed the lowest hardness of 60 ~ 100 Hv. A little bit higher hardness of 100 ~ 140 Hv was measured on the large size grey defect. More increased hardness of 140 ~ 170 Hv was observed on the oxide surface region with mall size black and/or grey defects. The highest hardness of 170 ~190 Hv was obtained from the oxide surface without defects. Distortion of the pyramidal indentation marks were observed only in the regions with a large size black and grey defects.
(Invited) The Subsurface Structure of Abraded Al-Zn-Mg-Cu Alloy and Its Effects on Corrosion
Authors: Wang Shan-Shan , Huber Dan , Poplawsky Jon , Colijn Henk , Frankel Gerald S.
Published: December 2020

Surface abrasion, sometimes followed by polishing, can create an altered surface layer (ASL) with thickness of a few hundreds of nanometers, which has different microstructure than the underlying bulk. Such an ASL typically contains ultrafine subgrains, and second phase particles that result from unusual phase transformations. ASLs have been shown to exhibit a different corrosion resistance than the underlying matrix, and can be either more susceptible or more resistant to corrosion. In this work, the ASL microstructure of AA7055 was studied at the early stages of natural aging right after surface abrasion using transmission electron microscopy (TEM) and atom probe tomography (APT). For the as-abraded ASL, the pre-existing η′/η precipitates and grain boundaries were deformed and aligned along the abrasion direction. However, for the abraded and 7-day natural aged bulk sample, ultrafine subgrains formed in the localized region of the ASL, and MgxZny and Al2Cu particles precipitated at the subgrain boundaries. To accelerate the precipitate kinetics of the ASL, the bulk abraded sample was heated at 50 oC for 1 h; more subgrains and Al2Cu particles formed in the whole ASL. Potentiodynamic polarization testing was performed on the abraded and aged bulk samples during immersion in NaCl solution. With increasing post-aging temperature and time, the breakdown potential of the ASL increased.

Acknowledgements: focus ion beam and TEM were conducted at Center for Electron Microscopy and Analysis at The Ohio State University. APT was conducted at Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, which is a U.S. DOE Office of Science User Facility.
Modeling Study of LixNi0.5Mn1.5O4 Electrode Behavior with Multiple Characteristic Particle Sizes
Authors: Xie Yuanyuan
Published: December 2020

High voltage LixNi0.5Mn1.5O4 (LNMO) spinel is an attractive cathode material for Li-ion battery to meet today’s need of high energy density. One of issues that challenges the implementation of LNMO is the invariant voltage with state of charge in the charge-discharge operations of a battery. This is believed to be originated from two consecutive phase transition processes of LNMO in the cycling. In this study, a mathematical model is developed to understand the impact of multiple characteristic particles on the voltage behavior of LNMO electrode in the charge-discharge process, which couples local phase change with lithium transport process. Effect of varied particle size on the electrode voltage behavior and charge-discharge capacity is simulated and analyzed by the developed model. Obtained results indicate that varied size range of LNMO particles can significantly influence the electrode performance and discharge capacity at different operating conditions. Further, mixed particles can influence the path-dependent voltage behavior of the LNMO electrode due to the phase transition. The comparison between this developed model and current existing models will be discussed at last, especially on the prediction of voltage behavior of multiple particle size LNMO electrode.
Single-Crystal Nickel-Rich Layered Oxide Cathodes Under High Voltage
Authors: Qian Guannan , Li Linsen , Liu Yijin , Ma Zi-Feng
Published: December 2020

Nickel-rich layered oxide materials LiNixCoyM1-x-yO2 (x>0.5, M=Mn or Al, NMC or NCA) have been considered as a mainstream choice for electric vehicle (EV) batteries in recent years, which have higher energy density than polyanion-type materials and can remarkably extend the mile range of EVs. In NMC/NCA, the energy density can be improved by increasing the nickel content or the cut-off voltage. Increasing the nickel content can effectively improve the energy density but lead to low thermal stability. Increasing the cut-off voltage to improve the energy density may result in poor structure stability, such as cation mixing on surface and intergranular cracks in bulk.

Here we synthesized the Zirconium coating single-crystalline LiNi0.6Co0.2Mn0.2O2 (ZNMC622) by molten salts method to achieving both high energy density and high thermal stability. ZNMC622 can deliver over 190 mAh g-1 at 4.5 V, which is close to the specific discharging capacity (~195 mAh g-1) of LiNi0.8Co0.1Mn0.1O2 at 4.3 V. The cycling tests show that ZNMC (4.5 V) has much higher capacity retention and retained 80% of initial capacity after 600 cycles than the capacity retention of NMC811 (4.3 V). It can be concluded that Zirconium coating can improve the particle surface stability at 4.5 V and single-crystalline structure can eliminate the intergranular cracks in bulk. Meanwhile, lower nickel content of ZNMC has better thermal stability, even at 4.5 V, the exothermic peak temperature and generated heat of ZNMC is obviously smaller than the counterpart of NMC811 (4.3 V). In conclusion, ZNMC is a promising cathode material with both high energy density and safety, especially suitable for EV batteries.
Design and Large-Area Fabrication Considerations for 3D Lithium-Ion Battery Electrode Architectures
Authors: Cobb Corie Lynn
Published: December 2020

Technology progressions in wearable devices, portable electronics, and electric vehicles have motivated a shift in Lithium-ion batteries to accommodate rapid charge, long cycle life, high power and high energy performance in more compact packaging. An emerging trend to address this technology shift is employing three-dimensional (3D) electrode architectures and Additive Manufacturing (AM) methods to rapidly fabricate batteries with customized geometries on a micron to millimeter scale, changing the way we fundamentally design and manufacture energy storage devices. 3D electrode architectures enhance ion transport in existing intercalation materials, thereby increasing gravimetric and volumetric energy and power densities relative to conventional batteries. Typically, increases in power density are only possible through sacrifices in energy density. Our research has shown that 3D electrode architectures can mitigate these trade-offs. This talk will focus on promising design and AM fabrication methods developed in our research group for high-performance 3D Lithium-ion batteries to enable customizable and scalable electrode architectures for a wide range of applications.
Characterizing Coupled Transport Phenomena in Large-Format Lithium-Ion Pouch Cells Using Lock-in Thermography and Laser Scanning
Authors: Chu Howie , Monroe Charles W.
Published: December 2020

Management of battery systems is difficult due to the variety of physical processes that occur when a battery is put under an electrical load. These processes produce macroscopic side effects, such as stress/strain and temperature evolution, which originate at the electrode level. The electrochemical-thermal-mechanical phenomena in battery cells are highly coupled in applications such as electric vehicles. Because microscopic effects in battery electrodes can propagate into larger length scales such as the cell and pack levels, there are changes on the outside that can be observed.

Contact-free, non-destructive methods for measuring changes in battery temperature and strain could serve as tools to determine a battery’s second-life prospects, and could also aid early fault detection. The lock-in thermography technique has been used to determine faults and locate defects within cells.1 It has also been shown that mechanical stresses can be used to monitor state of health (SOH) and state of charge (SOC).2,3 Laser scanning has also been implemented to generate strain distributions showing local mechanical effects during electrochemical cycling.4

A first step in understanding highly coupled systems is to characterize the individual phenomena in isolation. Figure 1 presents a contour plot that shows the result of a zero-displacement experiment, where the evolution of equilibrium stress within a constrained 3-cell battery pack is measured at various SOCs and at various ambient temperatures. This experiment has shown that thermally induced volume change can contribute as much to mechanical forces within a cell as intercalation/deintercalation stresses. In high-power applications such as electric vehicles, we expect to see consequences from both of these factors. So, we will be developing an experimental set-up that combines the techniques of lock-in thermography and laser scanning to simultaneously capture 2D strain and temperature distributions that arise in response to different current input signals. Data from the individual techniques, plus the combined experiment, can be used to see how a battery’s response changes as a consequence of its thermal and mechanical state, and how the relative contributions of temperature and strain can affect battery operation.

References

Robinson, J. B. et al. Detection of Internal Defects in Lithium-Ion Batteries Using Lock-in Thermography. ECS Electrochem. Lett.
4, A106–A109 (2015).

Cannarella, J. & Arnold, C. B. State of health and charge measurements in lithium-ion batteries using mechanical stress. J. Power Sources
269, 7–14 (2014).

Mohtat, P., Lee, S., Siegel, J. B. & Stefanopoulou, A. G. Towards better estimability of electrode-specific state of health: Decoding the cell expansion. J. Power Sources
427, 101–111 (2019).

Rieger, B. et al. Multi-directional laser scanning as innovative method to detect local cell damage during fast charging of lithium-ion cells. J. Energy Storage
8, 1–5 (2016).

Figure 1
(Invited) Resolution of the 1st Capacity Loss of Layered Oxide Cathodes
Authors: Zhou Hui , Pei Ben , Xin Fengxia , Chernova Natasha , Whittingham Stan
Published: December 2020

Layered transition-metal oxides are the dominant cathodes in present commercial Li-ion batteries, and are also the leading choice for electric vehicles, because much higher capacity can be obtained with high Ni content, which has the potential to achieve the cell-level energy density above 300 Wh/kg for NMC 811. However, the large 1st capacity loss (~ 15% of the charging capacity) limits the achievable capacity for this attractive cathode materials. If this capacity loss can be eliminated, the energy density could 400 Wh/kg. Our initial studies have found that ~ 80% of the 1st capacity loss of NMC 811 can be attributed to slow lithium diffusion at high lithium concentrations; this may be due to the divacancy diffusion mechanism for Li ions in the layers of the structure. The dramatic drop of the Li divacancy concentration can cause the sharp decrease on Li ion diffusion. However, the layered oxide cathode, LiCoO2, has a much smaller 1st capacity loss, 5 mAh/g vs. 27 mAh/g for 811 for the same Li extraction of 120 mAh/g; there appears to be little kinetics limitation (Figure 1). A systematic study is underway to understand the reasons for this difference. The results of this study will be described, and strategies to mitigate the 1st capacity loss in NMC will be discussed. This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy, through the Advanced Battery Materials Research Program (Battery500 Consortium).

Figure 1
Microstructure Modified Ni-Rich Cathode Material By Microscale Concentration Gradient for High Energy Density Li-Ion Batteries
Authors: Kim Un-Hyuck , Sun Yang-Kook
Published: December 2020

A concentration gradient (CG) Li[Ni0.9Co0.05Mn0.05]O2 cathode in which Li[Ni0.94Co0.038Mn0.022]O2 at the particle core is encapsulated by a 1.5-μm-thick CG shell with the outer surface composition Li[Ni0.841Co0.077Mn0.082]O2 is synthesized using a differential co-precipitation process. The CG at the microscale combined with the radial texturing of the refined primary particles in the CG shell layer protracts the detrimental H2 → H3 phase transition1,2, providing with the rise to sharp changes in the unit cell dimensions. This protraction, confirmed by in-situ X-ray diffraction and transmission electron microscopy, allows effective dissipation of the internal strain generated upon the H2 → H3 phase transition, markedly improving cycling performance and thermochemical stability as compared to those of the conventional without CG Li[Ni0.9Co0.05Mn0.05]O2 cathode3-6. The compositionally partitioned cathode delivers a specific capacity of 229 mAh g-1 and exhibits capacity retentions of 88% after 1,000 cycles in a pouch-type full cell (cf. 68% for the conventional cathode). Thus, the proposed cathode material provides an opportunity for the rational design and development of a wide range of multi-functional cathodes, especially for Ni-rich NCM cathodes, by compositionally partitioning the cathode particles and thus optimizing the microstructural response to the internal strain produced in the 100% depth of discharge state.

Reference

U.-H. Kim, S.-T. Myung, C. S. Yoon and Y.-K. Sun ACS Energy Lett.
2017, 2, 1848-1854.

H.-H. Ryu, K.-J. Park, C. S. Yoon and Y.-K. Sun Chem. Mater.
2018, 30, 1155.

Y.-K. Sun, S.-T. Myung, B.-C. Park, J. Prakash, I. Belharouak and K. Amine. Nat. Mater.
2009, 8, 320.

U.‐H. Kim, E.‐J. Lee, C. S. Yoon, S.‐T. Myung and Yang‐Kook Sun Adv. Energy Mater.
2016, 6, 1601417.

D.-W. Jun, C. S. Yoon, U.-H. Kim and Y.-K. Sun Chem. Mater.
2017, 29, 5048.

U.-H. Kim, S.-T. Myung, C. S. Yoon and Yang-Kook Sun ACS Energy Lett.
2017, 2, 1848.
(Invited) Electrolyte Design for Li Batteries
Authors: Wang Chunsheng , Chen Ji , Borodin Oleg
Published: December 2020

Li metal, with the lowest thermodynamically achievable negative electrochemical potential and the highest specific capacity (3860 mAh g−1), is the ultimate anode choice for Li batteries. However, the highest reported Li plating/stripping Coulombic efficiency (CE) of 99.5% after extensive efforts is still too low for the Li metal-free (all the Li metal in cycling comes from cathode, without anode pre-lithiation) Li metal batteries. The low CE is attributed to both non-uniform Li plating/stripping on the lithiophobic Cu current collector and Li dendrite growth through lithiophilic organic-inorganic solid electrolyte interphase (SEI) formed in carbonate electrolytes. Here, we use a lithiophilic Bismuth graphite blend (Bi-Gr) substrate to replace lithiophobic Cu current collector to seed a uniform Li nucleation, and form a lithiophobic LiF-rich SEI rather than lithiophilic organic-inorganic SEI to suppress Li dendrite growth. Molecular dynamics simulations reveal the preferential reduction of anions in 2 M LiPF6 in tetrahydrofuran/2-methyl tetrahydrofuran (2.0 M LiPF6-mixTHF) electrolyte to generate LiF-rich SEI on plated Li. Bi-Gr substrate and 2.0 M LiPF6-mixTHF electrolyte enable the Li anodes to achieve a record high CE of 99.83% at a high capacity of 1.0 mAh cm−2 and current of 0.5 mA cm−2. The Bi particles serve as dispersed nucleation centers that promote uniform Li deposition with strong adhesion to the substrate to avoid dead Li, while the lithiophobic LiF-rich SEI promotes lateral Li growth and suppresses the vertical Li dendrite growth even at a high current density of 3.0 mA cm−2 and high areal capacities of 3.0 mAh cm−2. The regulation of Li nucleation and growth enables the Li metal-free LiFePO4 full cells to achieve 100 cycles at a practical areal capacity of >2.0 mAh cm−2. This manuscript highlights the benefits of simultaneous substrate design to improve Li nucleation and electrolyte design to promote lithiophobic SEI growth, enabling a promising and practical route Li metal-free Li metal batteries
(Invited) Surface Reactions of Electrolyte with LiNixCoyMnzO2 Cathodes for Lithium Ion Batteries
Authors: Lucht Brett L.
Published: December 2020

Layered metal oxides with high nickel content are commonly used cathode materials in commercial lithium ion batteries due to high capacity and lower cost resulting from higher nickel content and lower cobalt content. Cathodes with increased nickel content suffer from rapid capacity fade due to a combination of thickening of the anode solid electrolyte interphase (SEI) and impedance growth on the cathode after extended cycling. While transition metal catalyzed degradation of the anode SEI has been widely proposed as a primary source of capacity loss, we propose that a related acid induced degradation of the anode SEI also occurs.
(Invited) Elucidating the Role of Mo during the Passivation of Ni-Cr-Mo Alloys: Real Time Analysis of Elemental Dissolution and Surface Enrichment
Authors: Li Xuejie , Henderson Jeffrey D. , Shoesmith David W. , Noel James , Ogle Kevin
Published: December 2020

Molybdenum is a common alloying element used in Ni-Cr and Fe-Cr alloys to improve their passive properties. Despite its ubiquity, the precise role Mo plays during passivation remains poorly understood. Recently we have investigated the role of Mo in commercial allows during both passive film formation [1] in acidic solution and during transpassive dissolution and repassivation in neutral chloride solution [2] using atomic emission spectroelectrochemistry (AESEC). In this work we refine the conclusions of the previous studies by working with pure binary and ternary alloys, Ni22Cr wt.% and Ni22Cr10Mo wt.%, the simplicity of which permits a clearer picture of the underlying mechanisms. The dissolution rates of Ni, Cr, and Mo and the surface enrichments of Cr and Mo were determined as a function of time during electrochemical experiments and film composition and oxidation state information was obtained by X-ray photoelectron spectroscopy (XPS). For both alloys, following cathodic removal of the passive film (activation), a spontaneous open circuit passivation was observed at ≈-0.25 V vs. SCE which involved the enrichment of both Cr and Mo. Stepping the potential further into the passive domain (+0.3 V vs. SCE) lead to a further enhancement of the Cr enrichment but a partial dissolution of the Mo enrichment.

The XPS results suggest that Mo dissolution may be attributed to the oxidation of the less soluble Mo(IV) to more soluble Mo(VI) species as suggested in our previous work with a commercial Ni alloy [1]. The suggestion is that Mo enriches on the surface only during a certain domain of potential and this suggests the hypothesis that Mo facilitates the initial growth of the passive film.

“The Passivation of Ni-Cr-Mo Alloys: Time Resolved Enrichment and Dissolution of Cr and Mo during Passive-Active Cycles”, X Li, K Ogle, J. Electrochem. Soc. 166 (2019)C3179-C3185.

“Molybdenum surface enrichment and release during transpassive dissolution of Ni-based alloys”, JD Henderson, X Li, DW Shoesmith, JJ Noël, K Ogle, Corrosion Science 147(2019)32-40

Figure 1
(Invited) Innovative 3D-Printed Flow-Type Electrochemical Microcell for Ultra-High Spatial Resolution Electrochemistry
Authors: Summers Kodi , Chidambaram Dev
Published: December 2020

Advances in 3D-printing technology have been used to design and develop a customizable flow-type electrochemical microcell that provides analytical resolution comparable to that of conventional glass capillary-based electrochemical microcells. In addition to being highly reproducible compared to the fabrication of glass capillaries, the advantages of this design are increased durability, decreased production costs, and better control over design parameters while maintaining ultra-high spatial resolution. The design is a three-component microcell that combines 3D printing with conventional machining to allow rapid prototyping and testing of flow designs and apertures sizes while maintaining a consistent foundation upon which the design can be built. The key benefit of the three-component design is the ability to replace parts as needed without complete disassembly. The design and application of two classes of flow-type electrochemical microcell, high-resolution (~100 µm spot size) and ultra-high resolution (~10 µm spot size), will be presented. Additionally, the proposed prototype introduces the practicality of a six-axis robot arm for positioning the microcell and is advantageous over a conventional three-axis gantry system allowing for the analysis of irregular sample geometries. The microcell prototype was tested and evaluated to demonstrate repeatability in use, accuracy in spatial resolution and experimental results, and capability in the analysis of various materials and surface finishes. The ease of use and endurance of the design is also demonstrated through repeated use. This microcell has the potential for applications in corrosion, electrodeposition, and electroanalysis, amongst others.

Acknowledgements: This work was supported by the United States Nuclear Regulatory Commission (NRC) under contract NRC-HQ-84-16-G-0033. Ms. Nancy Hebron-Israel serves as the program manager.
(Invited) In Situ Observation of Anomalous Hydrogen Evolution on Mg Under Anodic Polarization
Authors: Chu Peng-Wei , Su Yu-You
Published: December 2020

Mg alloys have long been considered a promising lightweight alloy system for various applications including consumer electronics, transportation, and medical equipment. However, owing to their high reactivity, Mg alloys cannot be used without proper coatings or surface treatments. Nevertheless, the chemical reactivity of Mg also opens up new ideas, such as the development of Mg-based biodegradable body implants and Mg metal battery systems. Unlike other metallic elements, Mg possesses a unique electrochemical response, especially under anodic polarization. To be specific, the rate of water reduction and hydrogen gas evolution, which is the dominant cathodic reaction on Mg in aqueous solutions, opposingly accelerates with the increase in anodic polarization. This phenomenon is the notorious negative difference effect (NDE) of Mg, or recently coined as the “anomalous hydrogen evolution”. Even after decades of research, the underlying mechanism of this peculiar electrochemical response of Mg is still under debate and yet to be elucidated.

In order to have a clear picture of how the anomalous hydrogen evolution is related to the dissolution of Mg under anodic polarization, a customized cell was designed to enable high resolution in situ observation of the hydrogen evolution sites and surface morphology on Mg with an optical microscope. The compact cell is small enough to fit under the optical microscope with a short working distance at high magnification (50x-500x). The cell and the equipped reference and counter electrodes are connected to a potentiostat/galvanostat to control and monitor the polarization of the Mg working electrode. Additionally, a dynamic fluid control system is used to regulate the solution flow rate in the cell and constant circulation to avoid chemical or pH shifts. Additionally, the flowing solution also flushes away hydrogen bubbles attached to the electrode surface and ensure an unblocked view of the Mg surface. From this experimental setup, the anomalous hydrogen evolution under anodic polarization was found to be closely related to the actively propagating localized corrosion front of Mg. The relationship between hydrogen evolution response, applied anodic polarization, solution flow rate, as well as possible negative difference effect mechanisms, will be discussed.

Figure 1
(Invited) Ions, Electrons, and Phonons: On the Movement of Charge through Solids
Authors: Melot Brent C
Published: December 2020

Li-ion batteries are ubiquitous; powering our cell phones, tablets, and laptop computers. Yet, we’ve almost exclusively relied on materials that adopt the same ordered rock salt structure type for over 20 years. What makes these materials so special and why is it so hard to move beyond them? This talk will present work our group has done to create a deeper understanding of the fundamental materials criterion required to move Li-ions through densely packed solids and outline new design principles for the development of next-generation intercalation hosts. Special attention will be paid to how changes to ionocovalent character of the chemical bonding can influence the mobility of not only the alkali ions, but also the redox-active transition metal centers.
(Invited) Surface Characterisation of Ni-Rich NMC Materials Stored in Various Environments
Authors: Guyomard Dominique , Laurita Angelica , Cabelguen Pierre Etienne , Zhu Liang , Dupré Nicolas , Fernandez Vincent , Hamon Jonathan , Moreau Philippe
Published: December 2020

In order to obtain higher energy densities for electromobility applications, the market is now heading towards high-nickel content NMCs. However, these materials suffer from severe gassing issues decreasing the cycle life and causing safety problems. While it is agreed that the O2 evolution is coming from oxygen lattice oxidation at the end of charge, the source of CO and CO2 gassing is still under debate.

In this context, we report here a systematic study of NMC811 pristine material surface contaminations obtained after storage in different controlled environments. We use a multi-analytical approach involving combined MAS-NMR, XPS and STEM-EELS to provide a full material characterisation before cycling. The chemical environment of the Li present in the paramagnetic bulk of the material is successfully determined by means of 7Li MAS-NMR at low field (200 MHz). High field 7Li MAS-NMR (500 MHz) allows the quantification of the surface diamagnetic Li. Low field 1H MAS-NMR gives insights on the proton bulk and surface environments. STEM-EELS mapping is performed with both high energy and high spatial resolution using our new TEM/STEM Themis Z G3 (Thermo Fisher Scientific) equipped with a double camera GIF spectrometer. We obtain a good multi-elemental chemistry mapping quantification as well as the accurate analysis of the fine structure of the L3/L2 Ni edges thanks to the use of an excited monochromator.

Putting together all characterisation results, we achieved a thorough analysis of primary particles surface contamination after different controlled storage conditions, that will be correlated with gassing measurements and cell cycling stability.
Effect of Ni Content on the Initial Corrosion Resistance of Steel in Atmospheric Environment
Authors: Kiyoizumi Kota , Ono Yuichi , Katayama Hideki , Hoshi Yoshinao , Watanabe Hikari , Shitanda Isao , Itagaki Masayuki , Akashi Takaya , Satoh Hina , Nagasawa Makoto
Published: December 2020

Weathering steels with a protective rust layer are well known to exhibit high corrosion resistance in mild corrosive environment for a long time even if it is used without paint. However, they do not generally show high corrosion performance in coastal area. Therefore, there have been numerous reports on the corrosion resistance and corrosion mechanism of weathering steel by exposure tests, electrochemical measurements, and rust analysis. However, the detailed effects of additive elements such as Ni and Cr on corrosion resistance have not been clarified. In this study, we focused on Ni as an additive element, and investigated the effect of Ni addition on the initial corrosion resistance of Fe-Ni alloy with different amounts of Ni by corrosion monitoring and electrochemical measurement under atmospheric corrosion environment. Fe (Fe : 99.7%), Fe-3mass% Ni, and Fe-5mass% Ni (Fe, 3Ni, and 5Ni) were used as the samples. The concentric ring type corrosion sensors (corrosion sensor) and the electrodes embedded in an epoxy resin were prepared for an atmospheric corrosion monitoring and for an electrochemical measurement, respectively. The wet and dry cyclic corrosion test was conducted in the chamber set at 25°C and 60% RH after adding 100 µL droplet of a 0.01 mol dm-3 NaCl solution. During the corrosion test, the atmospheric corrosion behavior was monitored by continuously measuring the impedance at low frequency (10 mHz) and high frequency (10 kHz) by a corrosion monitor. On the other hand, polarization curves were measured with a three-electrode system from the immersion potential. The scanning rate was set at 0.5 mV / s. In addition, the electrochemical impedance measurements were performed for the samples with and without passive film, in order to investigate the characteristic of the sample surface. The impedances were measured at 10mV of applied potential with the frequency range from 100 kHz to 10 mHz.

The corrosion rate of the steel content Ni in the first cycle was less than one-tenth that of Fe, and was almost the same for 3Ni and 5Ni. However, the corrosion rate after the second cycle decreased with increasing Ni content, and 5Ni showed a low value for a long time. This indicates that the Ni-content steel shows high corrosion resistance in the initial corrosion process. Almost the same oxygen diffusion limited current was observed in the cathodic polarization curves of all samples. On the other hand, the anodic currents of 3Ni and 5Ni, which are considered to correspond to the dissolution of Fe, were about one digit smaller than that of Fe. The impedance of Ni-content steels was larger than that of Fe. However, this result was not agreement with the corrosion monitoring results. Furthermore, the result of surface alalysis will be introduced in our poster.
Addition of an Eco-Friendly Corrosion Inhibitor in Self-Assembled Monolayers Coatings to Improve Pitting Corrosion Resistance of Stainless Steel
Authors: Rougier Agathe , Melot Jean Marie , Doche Marie-Laure , Touyeras Francis , Roizard Xavier , Lallemand Fabrice , Hihn Jean-Yves
Published: December 2020

In automotive industry and equipment manufacturers, treatment by phosphatation [1] is used both as an adhesion primer before painting and as a lubricant coating [2]. This treatment also offers a good protection against corrosion. However, phosphatation is quite harmfull for the environment, producing a lot of waste to be treated. With regards to toxicity, it is composed of concentrated acids, nitrates and nitrites. Eventually, OEM are working to reduce the thickness of this coating which is typically in the range 2-30 μm. The objective of our research is to propose an alternative to steel/phosphate systems by thin organic coating on 304 stainless steel, a low carbon content substrate free of Molybdene available at affordable costs

To fit with the required specification while being as attractive as possible, this alternative coating must present a thickness reduced to a few nanometers, be environmentally friendly, non-toxic and easy to use. It must keep the main properties of phosphatation which consist in adhesion or anti-wear. Self-assembled Monolayers (SAMs) [3] coatings were chosen with addition of Aloe Vera as an ecological corrosion inhibitor [4][5]. SAMs are tunable by adjusting either their terminal group or the length of the carbon chain to obtain the desired surface properties and corrosion resistance. Three different terminal groups combined with four carbon chain lengths have been tested to find the molecule providing the best protection against corrosion.

An electrochemical study is carried out to quantify protection against pitting corrosion in a chloride-containing medium. The substrate used being a 304 stainless steel. As pitting corrosion mechanism involves both stable and unstable pits, two types of electrochemical methods are used. Pulsed potentials technic will highlighted unstable pits, while stable pits are analysed by cyclic voltammetry. These measurements are supported by surface analysis (SEM, EDS).

[1] T. W. COSLETT, Treatment of iron or steel for preventing oxidation or rusting, British patent 8667 and US patent 870937, 1906 et 1907

[2] J. BOGI, Phosphate conversion coatings on steel, J Mater Sci (1977) 12, 2235-2240

[3] A. ULMAN, Formation and structure of self-assembled monolayers, Chem. Rev. 1996, 96, 1533-1554

[4] Devarayan, Kesavan, Green Inhibitors for Corrosion of Metals: A Review, Chem Sci Rev Letts, (2012)

[5] M. MEHDIPOUR, Electrochemical noise investigation of Aloe plant extract as green inhibitor on the corrosion of stainless steel in 1M H2SO4, J. Ind. Eng. Chem, (2015), 21, 318-327

Figure 1
(Invited) Intrinsic and Interfacial Ion Transport Properties of Nanostructured Polymer Electrolytes for Lithium Metal Batteries
Authors: Patel Shrayesh N.
Published: December 2020

Polymer electrolytes have demonstrated promise as solid electrolyte materials to enable lithium-metal batteries. However, majority of studies have focused only on thick samples (100’s of microns). It is important to note interfaces play a critical role on the performance of batteries, thus investigating polymer electrolytes in the context of nanothin films (5-100 nm) will lead to better understanding on how surfaces and interfaces influences charge transport properties. Here, we report on ion transport characteristics of nanothin films of PEO and LiTFSI blends as a function of salt concentration, temperature and film thickness. Ion transport measurements were successfully performed using impedance spectroscopy on films fabricated on custom-designed nanofabricated interdigitated electrode (IDE) devices. Importantly, thickness dependence study of ion transport shows a monotonic decrease in ionic conductivity upon decreasing film thickness from 250 nm to ca. 10 nm, and the effect is stronger at low salt concentrations. The decrease of ionic conductivity at thinner films originate from the increasing fraction of the immobilized layer near the polymer/substrate interface. In addition, these measurements reveal previously inaccessible diffusional processes that are critical to fully characterizing transport properties. We also extend our work towards nanostructured block copolymer nanothin film electrolytes (polystyrene-b-polyethylene oxide with LiTFSI). By carefully tuning the substrate surface energy, we can judiciously control block copolymer self-assembly and orientation to reveal previously inaccessible interfacial contributions that dictate the limits of ion-transport. Overall, our work shows that nanothin films in concert with IDEs is a powerful and versatile platform for studying a wide variety of confinement and surface functionalization effects on ion transport in a controlled and precise manner.
(Invited) Reaction and Failure Mechanisms of Layered Na1-XMO2 (M = Mn, Fe, Ni, and their solid solutions) As Cathode Materials for Sodium Ion Batteries
Authors: Lee Kyu Tae
Published: December 2020

Sodium ion batteries have been considered one of the most promising large-scale energy storage systems for grid energy storage because of their potentially low cost. The current sodium ion batteries, however, have slightly lower energy density than lithium ion batteries, implying that the energy density limitations offset the cost savings. In this regard, it is demanded to develop high capacity cathode materials for improving the energy density of sodium ion batteries.

Various layered-structured sodium transition metal oxides have been extensively examined as high capacity cathode materials. Recently, there have been remarkable improvements in the electrochemical performances of layered oxide materials, although they still present challenges, such as poor structural stability and severe electrolyte decomposition, leading to capacity fading during long cycling. In this connection, doped- and coated-layered oxide materials have been investigated in an effort to improve structural and interfacial stability.

In this presentation, we introduce our recent works involving the reaction and failure mechanisms of layered Na1-xMO2 (M = Mn, Fe, Ni, and their solid solutions) cathode materials for sodium ion batteries. We demonstrate the role of dopants in the reaction mechanisms of layered oxide materials. Their failure modes, such as crack formation mechanism and cation disordering, are also discussed. Then, we suggest a strategy for improving the electrochemical performance of layered Na1-xMO2.
Effect of Petroleum Pitch-Coating on the Electrochemical Performance of Graphite As Anode Materials
Authors: Lee Jong Dae , Jo Yoon Ji
Published: December 2020

Lithium ions batteries (LIBs) have become the most promising energy storage device in new energy field due to their potential utility as high-energy-density batteries for electric vehicles and hybrid electric vehicles. Graphite, which is the most widely commercialized anode material of LIBs, exhibits structural stability and excellent cycle characteristics. However, graphite has some problems to overcome. Due to the uneven SEI (Solid Electrolyte Interface) layer generated after the initial cycle, considerable irreversible capacity loss occurs. This results in electrode collapse and cycle instability especially in high-rate charging. Therefore, many researchers have been reported to improve the stability of graphite with carbon coating.

In this study, electrochemical characteristics of artificial graphite coated with petroleum pitch were investigated as anode materials of lithium ion batteries. To improve the capacity and stability of graphite, it was coated with petroleum pitch(SP, 150, 200 and 250 ℃). The physical properties of prepared samples were analyzed by MALDI-TOF, TGA, XRD, SEM and TEM. The electrochemical performances of graphite composites as an anode were evaluated by initial charge/discharge, cycle, rate performance, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) tests. The electrolyte used in the half cell was 1.0 M LiPF6 dissolved in organic solvents (EC:DEC=1:1 vol%).

It was found that the pitch(SP 250 ℃) anode materials had excellent electrochemical characteristics: good initial efficiency (92.9%), discharge capacity (343 mAh/g), cycle stability (97%), and rate performance (84.1% in 10 C/0.1 C) than that of pristine graphite.