bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Structural and Electrochemical Properties of LiNi0.9Co0.1O2 Ni-Rich Cathode in Lithium Ion Batteries
Authors: Aryal Shankar , Kahvecioglu Ozgenur , Durham Jessica , Lipson Albert , Pupek Krzysztof 
Published: July 2021

Advances in next generation Li-ion battery technology have been trending towards utilizing Nickel-rich cathode materials. One of the Ni-rich compositions, LiNi0.9Co0.1O2, have the potential to increase energy density while further reducing costs due to the reduced Cobalt content. This composition forms a highly layered structure, which provides superior electrochemical performance. In particular, it showed > 220 mAh/g initial discharge capacity at 0.1C rate but the capacity fades quickly with cycling. The main factors behind this performance deterioration with cycling are structural transformation of the cathode to the rock salt phase, parasitic reactions between the Nickel-rich cathode and electrolyte and gas release. Here, we report physical and electrochemical properties of industrial grade LiNi0.9Co0.1O2 cathode material synthesized by utilizing continuous co-precipitation reaction in a Taylor Vortex Reactor.
A thorough investigation of the mechanisms that make this material underperform other similar compositions was performed. In particular, the rate and long term cycling performance of the cathode material in half and full cell configuration were investigated. Synchrotron X-ray diffraction and X-ray absorption spectroscopy (XAS) of pristine and cycled cathodes after long term cycling will be discussed to understand the degradation mechanism. In-situ XAS at Nickel and Cobalt K-edge during the first two initial cycles will be discussed in detail to unravel the local structural changes and redox activity of Ni and Co in LiNi0.9Co0.1O2 cathode. Overall, this presentation will give a detailed understanding of this material’s synthesis, structure-property relationships, chemistry and electrochemical performance, which give new insights into the roles of Co and Mn in Ni-rich cathode materials.
(Invited) Anionic Redox Chemistry in Layered Oxide Cathodes
Authors: Tong Wei 
Published: July 2021

Li-ion battery remains as the critical energy storage device and starts to invade the large electrical vehicle (EV) market. Extensive efforts have been devoted to developing advanced layered oxide cathodes, including both stoichiometric and Li-rich layered oxides, for Li-ion batteries of even better performance. For all these cathodes, there is a clear need for the high-voltage cycling to obtain an even higher practical capacity. However, the redox reactions become more complex when charged at high voltages. Beyond the conventional transition metal (TM) redox, anionic oxygen becomes active and participates in the electrochemical reaction in these cathodes. The anionic oxygen activity involves both the reversible oxygen redox and irreversible oxygen loss accompanied by other byproducts resulting from the undesirable side reactions at high voltages.
In the past, my group has been focusing on understanding the redox chemistry, including both cationic and anionic redox reactions, in both stoichiometric and Li-rich layered oxide cathodes, especially towards the high-voltage cycling. We specifically investigated the electronic states of TM and O using combined electrochemical, soft X-ray absorption (XAS), resonant inelastic X-ray spectroscopy (RIXS) and in situ differential electrochemical mass spectrometry (DEMS) in the high voltage region to elucidate the explicit redox chemistry in various layered oxide cathodes. This presentation will highlight a summary on the different TM and O redox behaviors in these technologically relevant cathode materials for a close comparison. Of particular interest is the fundamental understanding of how the anionic oxygen participates in the electrochemistry of layered oxides with the presence of different Li and TM stoichiometry.
Quantification of the Internal Void Network upon Optimization of Synthesis Conditions for Lithium-Ion Cathode Materials
Authors: Allen Eva Michelle , De Andrade Vincent , Cabana Jordi 
Published: July 2021

Current industrial methodologies for lithium-ion battery cathode materials are suited to the production of well-defined, dense, spherical secondary particle structures assembled from nanocrystalline primary particles. Specifically, LiNixMnyCozO2 (LNMC) cathode material is synthesized by first growing the hydroxide precursor, NixMnyCoz(OH)2 (NMC), through a coprecipitation method using a stoichiometric ratio of mixed transition metal sulfate solutions, sodium hydroxide, and ammonia hydroxide pumped into a continuous stirred tank reactor (CSTR). Each new composition of cathode material requires an extensive synthesis parameter optimization study to refine the even formation of metal species, density, and uniformity of size and shape of the final cathode material. The characterization and visualization of the three-dimensional secondary cathode structure, internal morphology, and void network is an elusive task using traditional scanning electron microscopy (SEM) because it is 2D technique that requires the use of mechanical cross-sectioning which can cause the deformation of the internal structure. Yet the variation of the internal structure and density changes within LNMC secondary particles can have large effects on both the cycling kinetics, capacity, and lifetime of the final cathode material.
In this study, we present a five-parameter optimization study of Ni0.25Mn0.25Co0.50(OH)2 (NMC112) using our lab-built CSTR. The optimization and morphological changes of the primary and secondary particles during high temperature lithiation is investigated further. Using synchrotron-based transmission X-ray microscopy tomography (TXM) in combination with a novel deep learning semantic segmentation process, the three-dimensional cathode structure and internal pore network of LNMC112 particles was mapped across different lithiation temperature and reaction times. The deep learning semantic segmentation allowed for the quantification of void volume, shape, size, and final overall density of the cathode secondary particles. The results of these morphological differences show effects in both the kinetics and cyclability through galvanostatic cycling. The quantification of the three-dimensional cathode microstructure shown in this study is agnostic of the specific cathode composition. Therefore, it is highly suited to better inform optimization targets of the coprecipitation synthesis, as well as illuminating the importance the internal pore network of secondary particles.
NMR Study of LiCo0.96Al0.04O2 As a Positive Electrode Material for Li-Ion Batteries: Homogeneity and Role of Doping on Mechanisms
Authors: ER-Rami Fatima-Ezzahra , Duffiet Marie , Cabelguen Pierre-Etienne , Auvergniot Jeremie , Maxime Blangero , Carlier-Larregaray Dany , Delmas Claude 
Published: July 2021

LiCoO2 (LCO) is one of the most widely used positive electrode materials in lithium-ion batteries due to its high volumetric energy density which can be further improved by charging at high voltages. However, working at high potential (above 4.3 V vs. Li+/Li) causes a deterioration in cycling performance induced by structural instabilities, electrolyte oxidation and Co dissolution. Extensive studies have been devoted to increasing energy density by increasing the cutoff voltage. The substitution of cobalt with various metals is one of the classic methods, the choice of aluminum as dopant for example is based on several criteria: low cost and non-toxicity, a similar radius for Al3+ compared to Co3+ (0.535 Å vs. 0.545 Å) facilitates the replacement of the latter and maintains the structure leading to the complete solid solution LiCo1-yAlyO2.
We will focus here on LiCo0.96Al0.04O2, synthesized by the solid route and characterized by 7Li, 27Al and 59Co Nuclear Magnetic Resonance (NMR) and synchrotron X-Ray Diffraction (XRD). In addition to the characterization of the mean structure by XRD, the NMR allows us to study the local environments of the different nuclei. 27Al MAS NMR and synchrotron XRD studies revealed that the Al-doping in this material is homogeneous. 7Li MAS NMR indicates that its stoichiometry (Li/M=1.00) is ideal. The electrochemical study has shown that the phase transitions occurring during delithiation of LiCoO2, were partially eliminated by aluminum doping even with a low doping amount and the high potential mechanisms appear to be different. In order to better understand the role of Al-doping on the mechanisms involved during cycling, several phases LixCo0.96Al0.04O2 were prepared by electrochemical deintercalation and studied by 7Li, 59Co, and 27Al NMR and by XRD.
During lithium deintercalation, Co3+ is oxidized to Co4+ then one unpaired electron is generated in the t2g band of Co atoms (t2g
5eg
0). For 0.8 ≤ x ˂ 1.00 the 7Li MAS NMR shows that the system behaves locally as two phase domain: domain with localized electrons and domain with delocalized ones on Con+ ions (Knight shift), even for very low amount of deintercalation (x=0.98), thus the XRD results confirm the existence of the biphasic domain. Whereas, a single phase domain is observed for the deintercalated materials with 0.4 ≤ x ≤ 0.8 and also at the NMR time of scale a single signal (Knight shift) is observed. This signal increases in intensity at the expense of 0 ppm and shifts to the higher isotropic displacement values up to x=0.5 then decreases, thus the evolution of the chex lattice parameter is correlated with the signal shift. For x = 0.3 and x = 0.2: a new broad signal appears probably due to formation of new Li environment in stacking faulted layers (O1 type). These different contributions will be more detailed on the presentation.
Process-Induced ReRAM Performance Improvement of Atomic Layer Deposited HfO2 for Analog In-Memory Computing Applications
Authors: Consiglio Steven , Higuchi Hisashi , Ando Takashi , Jamison Paul , Seo Soon-Cheon , Kong Dexin , Kim Youngseok , Tapily Kandabara , Clark Robert D , Hopstaken Marinus , Cartier Eduard , Tsunomura Takaaki , Wajda Cory S , Soave Robert , Narayanan Vijay , Leusink Gert J 
Published: July 2021

Neuromorphic computing represents a potential paradigm shift from conventional von Neumann computing architecture and shows promise for achieving massive parallelism and power efficiency for such data-centric tasks as image recognition and language processing. Based on the concept of synaptic plasticity, human-like machine learning can be potentially realized by use of arrays of electronic synapses that function in an analogous manner to biological neurons. One of the key features of this type of computing is the ability to control synaptic weights in an analog-like fashion for use in both inference and training applications.
A number of existing device technologies in non-volatile memory systems exhibit attractive characteristics for such synaptic devices.[1,2] In particular, resistive switching devices (resistive random-access memory or ReRAM) can change and store their conductance value (G) in response to electrical stimuli making them potentially enabling for deep learning applications involving synaptic weights. For ReRAM devices, HfO2-based thin films can be utilized for filamentary oxide ReRAM and are an attractive option due to their fab-friendly processing and current implementation in high-volume manufacturing.
In this study, we evaluated atomic layer deposition (ALD) for the growth of HfO2 for integration in both front-end-of-line (FEOL) and back-end-of-line (BEOL) compatible test structures on 300 mm wafers in order to optimize electrical performance for use as synaptic device elements in neuromorphic architectures. The effect of oxidant in the ALD process was evaluated and it was shown that H2O outperformed O3 in terms of better uniformity and lower forming voltage. By utilizing a hydrogen-based plasma either after the deposition or inserted as an intermediate step during deposition we were able to further decrease forming voltage for a fixed dielectric thickness. Reducing deposition temperature to 200°C in conjunction with the hydrogen-based plasma treatment offered an additional tuning knob to further reduce forming voltage. Stable high-resistance switching (> 100 kΩ) with analog behavior in scaled BEOL devices was also obtained using this optimized HfO2-based ReRAM. Additionally, a tight distribution of forming voltage was obtained ensuring that 99.9999% devices in a 14 nm ReRAM module can be formed below the targeted voltage.
References

Kuzum et al., Nanotechnology, 24, 382001 (2013)

W. Burr et al., Advanced in Physics:X, 2, 89 (2016)
(Invited) Lactate Fueled Wearable Power Suppliers: From Enzymatic Biofuel Cell to Biosupercapacitor and Photobiobattery
Authors: Xiao Xinxin , Magner Edmond , Ulstrup Jens 
Published: July 2021

Nowadays, growing research in wearable biosensors for personal healthcare spurs the interest in flexible and miniaturized power suppliers. Enzymatic biofuel cells (EBFCs) [1] utilize oxidoreductases as catalysts, allowing to generate electricity from the chemical energy in sugars. Lactate exists in tear or sweat with a relatively high concentration, which can be the fuel for EBFC. Those applications require flexible, biocompatible and high-surface-area electrodes. Nanoporous gold (NPG) can be an excellent candidate meeting all the requirements [2]. We fabricate a mechanically stable and flexible NPG by electrochemically dealloying Au/Ag alloy films that are sputtered on plastic membranes [3]. The NPG has been biofunctionalized for EBFC applications. Flexible NPG based lactate/O2 EBFCs on commercial contact lenses register 1.7 ± 0.1 μW cm-2 in air-equilibrated artificial tear solutions, which is slightly lower than those obtained in PBS (2.4 ± 0.2 μW cm-2) [3]. A quasi-solid-state and flexible EBFC can be skin-worn consuming the stocking fuel in a hydrogel electrolyte, avoiding the constrain of the required sweat sugars [4]. The device can also function as a self-powered biosupercapacitor delivering pulses for over 600 cycles, with a power density over 10 times higher than that from the EBFC alone.
The combination of bioelectrodes and photoelectrode leads to a new-type photobiobattery. We will also describe a lactate/O2 photobiobattery using a dioxygen-reducing biocathode and a lactate-oxidising photocatalysts on the anode.

References

[1] X. Xiao, H.-q. Xia, R. Wu, L. Bai, L. Yan, E. Magner, S. Cosnier, E. Lojou, Z. Zhu, A. Liu, Tackling the Challenges of Enzymatic (Bio)Fuel Cells, Chem. Rev., 119 (2019) 9509-9558.
[2] X. Xiao, J. Ulstrup, H. Li, J. Zhang, P. Si, Nanoporous gold assembly of glucose oxidase for electrochemical biosensing, Electrochimica Acta, 130 (2014) 559-567.
[3] X. Xiao, T. Siepenkoetter, P.Ó. Conghaile, D. Leech, E. Magner, Nanoporous Gold-Based Biofuel Cells on Contact Lenses, ACS Appl. Mater. Interfaces, 10 (2018) 7107-7116.
[4] X. Xiao, E. Magner, A quasi-solid-state and self-powered biosupercapacitor based on flexible nanoporous gold electrodes, Chem. Commun., 54 (2018) 5823-5826.
Gas Evolution from Mixed-Acid Vanadium Redox Flow Batteries
Authors: Wittman Reed M , Pratt Harry , Anderson Travis , Preger Yuliya 
Published: July 2021

Mixed-Acid (MA) Vanadium Redox Flow Batteries (VRFB) improve on standard VRFBs’ energy density by adding hydrochloric acid (HCl) to the standard sulfuric acid (H2SO4) electrolyte. This improves the stability of the vanadium (V) in the solution, which allows for electrolytes with higher concentrations of V ions and increased operating temperatures. The addition of HCl to the system introduces a new safety risk, the evolution of chlorine gas (Cl2) from the catholyte.
In this study, we cycled an MA VRFB under a range of conditions to understand the fundamental causes of gas evolution. We constructed a single cell MA VRFB using a standard electrolyte composition of 2M H2SO4, 5M HCl and 2M V, with a gas analyzer sampling the head space of the catholyte chamber. Cl2 gas quantity was measured under systematically varied SOCs, cycling rates, electrolyte flow rates, electrode materials and electrolyte temperatures. Mechanisms of gas evolution at each condition were determined from analysis of the cycling data and the fundamental chemistry of the system. Conditions that lead to high rates of gas evolution were identified. This new understanding of gas evolution will aid development of safer MA VRFB systems that mitigate Cl2 formation during operation.
Sandia National Laboratories is a multi-mission 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.
Low Fluorine Colorless Polyimide Substrate for Flexible OLED Display
Authors: Kim Yong-Hae , Lee Won-Jae , Kim Su-Jung , Cho Nam-Sung , Kim Dong-Min , Kim Gi Heon 
Published: July 2021

Flexible display has become the main stream for the next innovative display. To build the flexible electronics, polyimide varnish is usually coated on the carrier glass with the thickness of a few micrometer and various devices such as flexible solar cell, flexible display, flexible printed circuit board, flexible terahertz sensor, and smart window [1]. Currently available colorless polyimide varnish is usually made of fluorine contained 6-FDA, which has good characteristics such as high transmittance, low yellow index, excellent solubility, but also has bad characteristics such as low decomposition temperature, high coefficient of thermal expansion, high cost, and environmentally unfriendliness due to fluorine. In this study, we make low fluorine contained polyimide varnish by substituting 6-FDA to BPDA + ODPA.
Fig. 1 shows the molecular structure of 6-FDA, BPDA, and ODPA. Low fluorine contained polyimide varnish is composed of 40% 6-FDA, 40% BPDA, 20% ODPA and it showed the excellent characteristics such as the glass transition temperature of 300 deg, the decomposition temperature of 366 deg, the yellow index of 2.2, the coefficient of thermal expansion of 20 ppm/deg, and the transmittance at 550 nm wavelength of 98.1%.
Because polyimide substrate made from coating polyimide varnish on carrier glass have to be protected using inorganic barrier material such as SiO2 and Si3N4. Also, transparent electrode is also required to apply voltage to the OLED display. Because the color of the polyimide substrate can be changed with the variation of barrier material thickness and transparent electrode thickness, we used optical simulator, Macleod, to access the transmittance change with the thickness change of SiO2 and Si3N4 as shown in fig. 2. Optimal thickness is selected at SiO2 of 400 nm and Si3N4 of 50 nm. The experimental transmittance is well matched with the simulation transmittance as shown in fig. 3.
Fabricated device will be detached using innovative laser lift-off (LLO) that utilized excimer laser which scan the interface between the polyimide substrate and the carrier glass from the backside [2]. Fig, 4 shows the laser irradiation and the detached wrinkle free polyimide substrate. Before the delamination, the polyimide substrate is clear, but shows yellowish color during delamination process. Optimum laser energy for the delamination is compared with the color index as shown in fig. 5.
We will make the OLED display on the polyimide substrate.

Yi et al., Solar Energy 195, 340 (2020),

Bian et al., App. Sur. Sci. 499, 143910 (2020).

Figure 1
(Invited) Achieving Stable Organic Transistors By Eliminating the Major Degradation Pathways
Authors: Jurchescu Oana D 
Published: July 2021

Organic semiconductors (OSCs) have attracted a great deal of attention over the past decades given their unique properties, which provide an opportunity to incorporate electronics in non-traditional areas such as bio-integrated devices, flexible and rollable displays or clothing. Coupled with low-cost processing and chemical versatility, these materials are gradually becoming an integral part of various components in contemporary optoelectronic applications. For example, the organic field-effect transistors (OFETs) represent the basic building blocks of displays, radio frequency identification tags and conformable sensors. Along with a performance that should match the application specific requirements, maintaining this performance during operation is a prerequisite for any technology. Therefore, identifying the sources and mechanisms leading to operational instabilities are crucial in eliminating their impact, to ultimately achieve the much-needed stability to make these devices components in real-life applications. In this presentation, I will discuss the sources of instabilities in organic transistors and how they manifest in device operation. I will then describe a technique which provides a reliable diagnostic tool to identify with high accuracy the environmental and operational degradation pathways occurring in OFETs during operation. By identifying the most probable degradation pathways, we developed new device design rules which resulted in OFETs with unparalleled operational stability in both staggered and coplanar configurations regardless of the active material (small molecule and polymeric OSCs), as confirmed by the constant mobility and exceptionally low threshold voltage shift of ΔVth
= 0.1 eV achieved under aggressive bias stress conditions for 500 min in ambient air.
The work was done in collaboration with Hamna F. Iqbal, Qianxiang Ai, Karl J. Thorley, Hu Chen, Iain McCulloch, Chad Risko, and John E. Anthony
Mediated Lithium-Sulfur Flow Batteries for Grid-Scale Energy Storage
Authors: Meyerson Melissa , Small Leo 
Published: July 2021

With the growth of intermittent renewable power sources, such as solar and wind energy, there is an increasing need for inexpensive, high capacity, grid-scale energy storage. The high capacity (1675 mAh/g) and low cost (~0.1 $/kg) of sulfur make Li-S batteries an ideal candidate to fill this need. However, sulfur has poor electrical conductivity and Li-S batteries are prone to polysulfide shuttling that decreases the battery life. In an effort to address these problems, we are developing a highly-scalable mediated Li-S flow battery using a lithium metal anode, solid state Li ion conductor separator, sulfur cathode, and a redox mediator. During discharge, the Li metal is oxidized to Li+ and the redox mediator (RM) is reduced. The RM will then react with the S returning to its oxidized form and enabling the formation of Li2S without the need for electrical contact between the S and counter electrode. The oxidized RM is then reduced again, and the process is repeated until all available S has reacted. A second RM with a potential lower than that of the Li-S reaction is used to enable the charge process. Two such mediators are decamethylferrocene (2.86 V vs Li/Li+) and cobaltocene (2.06 V vs. Li/Li+), Figure 1. The flow battery design has multiple benefits. First, the use of a solid state Li ion conductor mitigates polysulfide shuttling, thereby increasing the cycle life. Second, the issue of sulfur conductivity is addressed through use of the redox mediator, where the mediator can easily diffuse through the electrolyte reaching the sulfur and eliminating the need for excess conductive carbon additives. Third, the flow battery design enables physical separation of the anode and cathode, mitigating the potential for short circuiting and thermal runaway even if the Li does puncture the solid state electrolyte. Using this cell design, we examine the role of the solvent, anion, and polysulfide concentration on Li+ transport across the solid electrolyte interphase as well as the role of the mediation potential and interactions between the polysulfide and mediator.
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.

Figure 1