bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Cobalt Content on Charge Compensation Mechanism of LiNixMnyCozO2 Cathode for Lithium Ion Battery
Authors: Morita Yoshiyuki , Nakanishi Koji , Aubin Megan , Ogasa Hiroshi , Fujiwara Yoshiya , Kushima Akihiro 
Published: December 2020

LiCoO2 (LCO) is commonly used as a cathode for Li-ion batteries (LiBs) owing to its excellent intercalation nature, high voltage, and cyclic performance [1, 2]. However, LCO has issues due to the potential risk of future price increases of Co [3, 4]. Many efforts have been made to reduce the amount of Co in the cathode by replacing it with Ni and/or Mn, and LiNixMnyCozO2 (NMC) has been developed. NMC622, which contains 60 mol % of Ni in the transition metal composition, is now adopted in the majority of the electric vehicle battery chemistry. Although Ni-rich NMC is a promising alternative to low-Co cathodes, it is not clear whether the amount of Co can be further reduced from the present NMC622 without degrading cyclic stability. To further reduce the amount of Co, it is necessary to clarify the role of Co in the charge compensation mechanism and replace it with alternative elements with functions similar to those of Co.
In this study, we conducted XAFS, XRD and first-principles calculations for the NMC cathode with various transition metal composition ratios to clarify that the roles of Co, Ni, Mn, and O in the charge compensation mechanism. Synchrotron X-ray experiments were performed at SPring-8 and NewSUBARU synchrotron radiation facility in Japan. The first-principles calculations were carried out with Vienna Ab-initio Simulation Package (VASP) [5, 6], which uses plane-wave basis sets.
Fig. 1 shows the oxygen K-edge XANES spectra collected by the partial fluorescence yield (PFY) method at different states of charge (SOCs). As for the LCO, the peak intensity around 528 eV changed along with the SOC, suggesting that oxygen contributes to the charge compensation. Similar spectral changes were also observed with NMC111, NMC622, and slightly with NMC 811. In contrast, the white line energy in the Co L3-edge absorption hardly changed at any transition metal composition. Although there are various theories about the role of Co and oxygen in the charge compensation [7], our results show that there is no obvious change in the charge state of Co and oxygen contributes the most to the charge compensation in the LCO system. Detailed analysis including first-principles calculations will be discussed at the meeting.
[1] K. Mizushima et al., Mater. Res. Bull. 15, 783 (1980).
[2] A. Du Pasquier et al., J. Power Sources 115, 171 (2003).
[3] P.A. Nelson et al., Modeling the Performance and Cost of Lithium-Ion Batteries for Electric-Drive Vehicles, Argonne National Laboratory, 2012.
[4] Elsa A. Olivetti e
t al., Joule 1, 229 (2017).
[5] P. E. Blöch, Phys. Rev. B 50, 17953 (1994).
[6] G. Kresse et al., Phys. Rev. B 59, 1758 (1999).
[7] B. Li et al., Adv. Mater. 29, 1701054 (2017)

Figure 1
Pulsed Electrodeposition of Nanocatalysts for Energy Storage Applications: Mathematical Modeling and Experimental Studies
Authors: Karimi Shahram 
Published: December 2020

With the growing demand for clean energy, the need for affordable, efficient energy storage technologies has never been more urgent. Pumped hydro and compressed air storage technologies have been widely used, but they are heavily dependent on location and are not considered to be universal solutions. Secondary batteries, including Li-ion and lead-acid batteries, have played a major role in storing excess electrical energy, but they suffer from high cost, performance degradation over time, and environmental issues during use and disposal. Metal-air batteries have experienced a renaissance on account of their acceptable energy density, superior cycleability, enhanced stability and cost benefits compared with other commercially available batteries. Despite these desirable properties, metal-air batteries suffer from a number of thermodynamics and kinetics hurdles that must be overcome, if their widespread deployment is desired. One of the major impediments to wide-scale commercialization of metal-air batteries continues to be their inferior capacity and cycle stability. Part of these issues can be ascribed to the shortcomings of the cathode materials and structures in general, and the inferiority of their catalyst layers in particular. It is well established that nano-structuring battery components would improve their short- and long-term performance by enhancing reaction kinetics.
Nanocatalysts such as transition metals, platinum and manganese dioxide were electrodeposited on a number of conductive substrates, including carbon paper, carbon cloth and titania nanotubes (TNTs) with high aspect ratios. Catalyst electrodeposition was performed utilizing pulsed current electrodeposition with different waveforms, low duty cycles, and high peak deposition current densities. All catalysts were characterized using microscopy, spectroscopy and electrochemical techniques. The presence of nanocatalysts were confirmed by SEM and XRD and were found to be 2-5 nm for platinum and 10-50 nm for nickel and oxides of manganese.
A mathematical model was developed to determine the roles of various deposition process parameters on the size and catalytic activity of the resulting nanocatalysts in different environments. The model is based on progressive nucleation and takes into account some key contributing factors towards growth current and, ultimately, nucleation, including diffusion, ohmic and charge transfer phenomena. A varying diffusion coefficient during electrodeposition was also considered and evaluated. Model predictions were confirmed by experimental measurements with emphasis on platinum and manganese dioxide nanocatalysts for use in PEM fuel cells and metal-air batteries, respectively.
(Electrodeposition Division Early Career Investigator Award Address) Metal Patterning by Electrodeposition: Local Bipolar Electrochemistry and Additive-Derived Electrode Bifurcation
Authors: Braun Trevor Michael 
Published: December 2020

One of electrodeposition’s highest value applications is in manufacturing of electronic devices, ranging in scale from nanometer connections in integrated circuits up to millimeter scale features in printed circuit boards. The wide-range of feature geometries and substrate complexity (conducting, semiconducting, insulating, etc.) in this constantly evolving industry has driven extensive efforts to tailor both lateral and vertical material growth characteristics, diverging from more traditional electroplating applications focused on uniform films as applied to coatings. Like the electronics industry, techniques for 3D control of electrodeposition are consistently evolving. These methods include deposition through patterned masks (through-mask plating), use of sacrificial materials to form patterns (EFAB), localized electrodeposition using confined electrodes, and surface adsorbates that drive spatially-dependent active/passive regions through the coupling of local chemical and electrical gradients.
In this presentation, I will highlight recent advances in two of these areas: electrodeposition through confined electrodes and by influencing deposition kinetics with surface adsorbates. In the former, bipolar electrochemistry is combined with microjet electrodes to permit localized electrodeposition of a ‘pixel’ on a conductive surface without requiring electrical contact; patterns are produced by rastering the microjet similar to commercial 3D-printing methods. In the latter, electrolyte additives that inhibit deposition can induce spontaneous formation of spatially bifurcated active and passive regions; characteristics of the electrode topography, surface heterogeneity, and electro(chemical) transport through the cell determine the shape of 2D pattern formation. Electroanalytical measurements of these active/passive systems inform electrode shape-change models describing the interplay between transport and electrochemical kinetics. This fundamental insight permits control of an otherwise random bifurcation process that can be tailored for a variety of applications.
AuCu Catalysts with High Activity and Selectivity for Electrochemical Reduction of CO2 to CO
Authors: Han Gyeong Ho , Kim Junhyeong , Kim Hyunki , Hong Seokjin , Ahn Sang Hyun 
Published: December 2020

As the extensive usage of fossil fuels, the concentration of CO2 in the atmosphere has increased, and global warming becomes a critical problem. Recently various studies have been conducted to reduce the concentration of CO2. One attractive method to solve this problem is the electrochemical reduction of CO2. It produces feedstocks and useful fuels of C1 chemistry, such as CO, CH4, CH3OH and HCOOH at room temperature and ambient pressure. Among the useful products, the CO is known to have the economic benefit because the market price of CO is higher than other products. However, the electrochemical reduction usually suffers from huge energy losses due to the high overpotential originated form chemical stability of CO2. Therefore, development of a highly active catalyst is essential. Currently, Au-based and Au-based bimetallic catalysts are commonly used to convert CO2. To obtain highly activity and selectivity, the various investigates are being conducted to control properties, which their morphology, size, composition, facets and oxidation states. In addition, these properties can effect intermediate adsorption, grain size and electrochemical surface area.
Herein, AuCu nanoparticles were directly fabricated on carbon paper substrate by using electrodeposition method. The electrodeposition parameters such as precursor concentration and deposition time were changed to control the morphology and composition of AuCu catalysts. The AuCu nanoparticles were used as cathode for electrochemical carbon dioxide conversion in 0.5 M KHCO3 in H-type cell which was separated by proton conducting membrane. At a certain condition, the CO Faradaic efficiency of ~80 % was achieved at a potential of -0.7 VRHE. Further post-treatments such as anodizing or annealing methods were performed to change the control properties of the catalyst. And then, modification on catalytic performance was observed.
Real-Time Analysis of a Single Secondary Particle Using an Electrochemical Modeling
Authors: Song Jihun , Park Joonam , PARK SUN HO , Lee Yong Min 
Published: December 2020

Promising electrode active materials such as LiNiMnCoO2, LiNiCoAlO2 and LiFePO4 is made by a secondary particle containing millions of primary particles to improve its conductivity and diffusion. Therefore, design and analysis of the secondary particle are most important things to improve the performance of the active material so some groups are studying the intrinsic characteristics by a single particle measurement technique which cycle a half-cell of a single active material particle and lithium metal. With this method, we can calculate the diffusion coefficient, exchange current density
Nevertheless, it is almost impossible to see what happened inside the particle during cycling and it is hard to optimize particle design by this method to meet the required each condition including high power or long cycle life.
To overcome this situation, we developed a single particle model which can easily analyze inside of the particle as well as design the particle. To get the reliability of the model, we compared the experimental result by the single particle measurement technique and the simulation result. Using this model, we can estimate the real-time properties including distributions of lithiation, electric potential and overpotential inside the particle and concentration in a liquid phase.
Besides, we analyze the secondary particle with change of the particle design (solid volume fraction, primary particle size and secondary particle size)
Combined Experimental and Multi-Scale Modeling Approach to the Development of Electrocatalysts with Improved CO2 Reduction Activity Towards C2+ Alcohols
Authors: Morales Guio Carlos Gilberto 
Published: December 2020

The development of high performance catalysts for the production of fuels and chemical in electrochemical reactors call for a profound understanding of the processes occurring at multiple scales and emphasizes the importance of broadening catalyst design principles beyond the transition state theory to include fundamentals of mass and charge transport. The selective production of C2+ alcohols on cooper electrodes requires that multiple thermo-chemical and electro-chemical steps occur at the electrode-electrolyte interface at rates faster than those for the competing hydrogen and hydrocarbon evolution reactions. At the same time, the rates of most of these reactions are not only dependent on the intrinsic activity of copper, but are highly affected by the local environments that determine the rate of regeneration of reaction intermediates, the availability of proton sources for proton-electron coupled steps and the extend of the thermodynamic driving force for the formation of each of the multiple products.
In this talk, a mathematical model based on the Poisson-Nernst-Planck equation is presented that describes transport phenomena and ion migrations within an electrochemical cell. This models is shown as a valid tool for the rationalization of experimental observations and the normalization of experimental reaction rates to changes in the local concentration of species during electrocatalysis. Normalization of reaction rates to local changes in concentrations allows a better understanding of the nature of electrode/electrolyte interfaces during CO2 reduction to C2+ alcohols and the decoupling of mass transport effects and intrinsic kinetics. Charge transfer coefficients and pre-exponential factors are extracted from experimental data to describe the intrinsic activities of copper and other transition metal electrodes during the electrochemical reduction of CO2 to CO, alcohols and hydrocarbons. We demonstrate the rational application of this mathematical model in the design of more active and selective electrocatalyst for C2+ alcohol production by introducing cooperative catalysis schemes where gold nanoparticles generate high local concentrations of carbon monoxide intermediates on neighboring copper sites that catalyze the production of C2+ alcohols at higher rates than without gold. Electrode nanostructuring is also leveraged to create local environments withing electrode pores that increase the rate of C2+ alcohols formation. Finally, the extent to which these mathematical models could be used in the description and design of modular electrochemical reactors for practical applications is discussed to highlight challenges and opportunities of future electrocatalytic technologies for the production of C2+ alcohols from CO2.
Influence of Processing Route and Chemical Composition on Electrochemical Properties of High-Capacity Layered Oxide Cathodes
Authors: Fung Kenneth , Chang Chia Chin , Fung Kuan-Zong , Tsai Shu-Yi 
Published: December 2020

To obtain high-capacity Li ion batteries; oxide cathodes with layered structure still remain the ones that provide high enough capacities. It is known that electrons and Li+ ions are being extracted simultaneously in the charging process. During high-voltage charging, more ionic/electronic defects formed in layered oxides will be created. Thus, their electrochemical and structural properties are strongly affected by the formation and/or elimination of these defects. Higher defect concentration, like Li vacancies, VLi’, tends to destabilize its crystal structure. As a result, the phase transformation may occur in the cycled cathode. Accordingly, the capacity fading was frequently observed in cycled layered cathode due to the phase-changing process. Moreover, the existing defects in layered oxides are typically determined by the condition of fabrication processes, for instance the dopants and oxygen partial pressure.
In this study, two well-known layered oxides with fixed 80% Ni in the transition metal ion layer, namely NMC 811 and LiNi0.8Co0.15Al0.05O2 (NCA), were investigated. Their minor elements/dopants Mn and Al may play an important role on affecting their defect chemistry as well as electrochemical properties. Thus, their electrical/electrochemical/structural properties are examined as a function of the minor dopants, Mn and Al. First, the electrical measurement of NMC 811 and LiNi0.8Co0.15Al0.05O2 are conducted. Assembled cells using above-mentioned cathode and Li anode with desired liquid electrolyte were tested and cycled. SEM and XRD analyses were conducted on assembled and cycled cells. The analysis and results are illustrated based on the chemical characteristics of doping ions and the electronic/ionic defects induced.
Shedding Light about the Role of Proton Intercalation in Layered Cathode Materials By Means of First Principle Computations
Authors: Posada Perez Sergio , Rignanese Gian-Marco , Hautier Geoffroy 
Published: December 2020

Flammability, toxicity, and cost are only a few drawbacks about the use of organic liquid electrolytes. On the other hand, working in aqueous electrolyte would therefore be extremely beneficial especially to lower production cost and obtain higher safety and lower toxicity.
In contrast to organic electrolytes, where only the inserted metal ions can (de)intercalate in the electrode material, the use of aqueous electrolytes opens the possibility of proton co-insertion. But are protons able to intercalate in the electrodes? and if the answer is affirmative, which is the effect of proton intercalation in the battery performance?
Several (electro)chemical studies combined with first-principles computations have confirmed the easy protonation of layered electrodes at different ranges of pH values and this fact has been directly related with the detrimental in cathode materials. Nevertheless, several studies reported the excellent performance of layered LiCoO2 and LiCo1/3Ni1/3Mn1/3O2 as positive electrode -without coating- using neutral or basic salt in water electrolytes. Thus, it remains an open question: Why these layered cathode materials so prone to proton intercalation could perform as well in aqueous environment?
In this work, we use density functional computations to investigate the lithium/proton exchange in some well-known cathode materials. The analysis of the proton insertion mechanism has been carried out in the bulk and surfaces of these materials in order to demonstrated which specific chemical and structural features lead to electrochemically stable materials for aqueous batteries. To analyze the Li+/H+ exchange, several Li+/H+/vacancy orderings and arrangements were computed to study the phase stability at different pH values. This study provides fundamental investigations about the role of H-intercalation in the performance of aqueous battery operations.
Atomistic State of Hydrogen in Electrochemically Deposited Cu Films
Authors: Fukumuro Naoki , Tohda Kosuke , Yae Shinji 
Published: December 2020

Electro and electroless deposition of Cu films are widely used in the print circuit boards production. These electrochemical Cu deposition process are accompanied with the simultaneous hydrogen evolution, and the hydrogen co-deposition sometimes causes the voids and blisters1). However, the detail mechanism of such hydrogen-induced phenomena have not been clarified. We previously reported that the primary cause of the room-temperature grain growth observed in electrodeposited Cu films was the formation of superabundant vacancies induced by the hydrogen co-deposition2). In this study, the atomistic state of hydrogen co-deposited in the Cu films obtained by electro and electroless deposition and the influence of hydrogen on the microstructure of Cu films were investigated.
Cu films were electrodeposited from six different baths (sulfate bath, additive-containing bath, chloride bath, pyrophosphate bath, EDA bath, and EDTA bath) and electrolessly deposited from an EDTA bath. The amount and atomistic state of hydrogen in the Cu films were analyzed by thermal desorption spectroscopy (TDS). The microstructural analysis of the Cu films was performed by X-ray diffraction (XRD) and transmission electron microscopy (TEM).
In the electrodeposited Cu films with high hydrogen concentrations (x = H/Cu = 5.4 ~ 98.2×10-4), the room-temperature grain growth proceeded with the desorption of hydrogen during 7 ~ 21 days after deposition2). A pronounced desorption peak at 600 ~ 700 K due to the break-up of vacancy-hydrogen clusters3) was observed in the thermal desorption spectra of hydrogen from these Cu films.
In the thermal desorption spectra of hydrogen from electrolessly deposited Cu films, a pronounced peak at around 420 K and a small peak at 600 ~ 700 K were observed and the hydrogen concentration was x = 13.6×10-3. From the XRD measurements, the lattice expansion of about 0.14% was observed in the as-deposited Cu films, which was reduced with the desorption of hydrogen at room temperature after 7 days. These results suggest that the desorption peak at 420 K may be assigned to the desorption of hydrogen from the regular interstitial sites. In the TEM images of these Cu films, many nano-voids distributed in the crystal grains were observed. We consider that the hydrogen molecules trapped in the nano-voids should be desorbed at high temperature above 900 K. The high-temperature TDS measurements will be performed.

References

1) T. Sharma, A. E. Landry, A. Leger, D. A. Brown, T. Bernhard, S. Zarwell, F. Brüning, and R. Brüning, Thin Solid Films, 666, 76 (2018).
2) N. Fukumuro, H. Yoshida, T. Yamazaki, Y. Fukai, and S. Yae, J. Japan. Inst. Met. Mater., 80, 736 (2016).
3) Y. Fukai, M. Mizutani, S. Yokota, M. Kanazawa, Y. Miura, and T. Watanabe, J. Alloy. Comp.,
356-357, 270 (2003).