bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Reduced Order Model Derived from DFT with Uncertainty Estimation for the Understanding of Magnetic Cathodes
Authors: Houchins Gregory , Viswanathan Venkatasubramanian 
Published: February 2020

Li-ion cathode materials containing magnetic transition metals (Fe, Ni, Co, Mn, Ti) are the most promising materials for rechargeable batteries. The magnetic interactions of the transition metal ions play a significant role in determining the lithium intercalation-deintercalation process, capacity loss, and therefore are crucial for the optimization of cathodes materials and for the discovery of new candidate materials. A large body of work has been dedicated to the study of these materials through ab initio electronic structure calculations using density functional theory (DFT).
The Heisenberg Hamiltonian has previously been used in conjunction with DFT calculations to correctly find the magnetic ground states of materials for complicated structures with large number of possible spin configurations.[1] The mapping of a few DFT calculations to reduced-order models allows for the exploration of a much larger subset of parameter space with much more computational efficiency than DFT alone. We expand this spin Hamiltonian with other energetic contributions including an occupation and nearest neighbor electronic interaction terms. The parameters of this model can be tuned to high fidelity and therefore can accurately extend to high throughput. This reduced order model can then be used with Monte Carlo simulations to generate relevant phase spaces with high resolution and less compute power than comparable collection of DFT only calculations.
A unique aspect of this work is the incorporation of error estimation through the use of the Bayesian Error Estimation Functional (BEEF)[2] and apply that to the prediction of magnetic ground states [3]. This allows us to predict c-values related to the reliability of the prediction of magnetic states identified through the DFT calculations. We use this approach to systematically understand the magnetic properties of various Li-ion cathodes. We then apply that method to predict precisely the Li-NMC (Ni-Mn-Co) phase-diagram and calculate their corresponding voltages. We will report on a robust approach to carry out high-throughput screening of cathode materials using the developed method for uncertainty estimation.
[1] D. Morgan, B. Wang, G. Ceder, and A. van de Walle, Phys. Rev. B 67, 134404 (2003).
[2] J. Wellendorff, K. T. Lundgaard, A. Møgelhøj, V. Petzold, D. D. Landis, J. K. Nørskov, T. Bligaard, and K. W. Jacobsen, Phys. Rev. B 85, 235149 (2012).
[3] G. Houchins and V. Viswanathan to be submitted

Figure 1
Synthesis of MnO Nano-Particle@Flourine Doped Carbon and Its Application in Hybrid Supercapacitor
Authors: Feng Xiaoke , Qu Deyu , Xie Zhizhong , Wei Xi 
Published: February 2020

In order to meet the increasing demand for the high energy and high power in the same time, while neither secondary batteries nor double-layer supercapacitors cannot satisfy, a new energy storage device, hybrid supercapacitor, attracked lots of attentions in recent days. The new device hybrid the double layer capacitor electrode, which provides the high power density, with the secondary battery electrode, which supplys the high energy density. Various of lithium ion batteries(LIBs) electrodes are introduced into this hybrid system. As the alternative materials to the carbonaceous anode in commercial LIBs, numerous of transition metals have been studied as the anode of LIBs due to their high theoretical capacity, high safety and environmental benignity. Here, a transition metal MnO, a promising material used as anode in LIBs, worked with porous carbon materials to form a new lithium ion hybrid supercapacitor. In this device, MnO is used as negative electrode. Meantime the porous active carbon electrode serves as positive electrode. Similar with other transition metal materials, the intrinsic high resistance, large volume variation during the charge and discharge will still impede the MnO involving into the hybrid system. Especially the late one will cause the pulverization of the MnO materials and then the loosing contact between active materials and current collector. This will cause a significantly capacity fading and bad cycling stability. Since the high energy capacity, excellent cycle-ability and good rate performance are the major merits of hybrid supercapacitor, therefore those problems of MnO should be solved first.
To solve those problems, covering nano-sized MnO materials with conductive carbon layer is a proper approach. Furthermore, It is widely recognized that doping hetero-atom onto the carbon can change their electronic configuration and then improve the electrochemical performances of the carbon materials. Therefore, in this study, a fluorine-doped carbon encapsulated MnO nano-particle (MnONP@FC) was fabricated through a novel process. In this synthesis process, Nafion ionomers was used as the fluorine doped carbon precursor. As shown in Scheme 1, Mn ions are first self-assembly trapped within the Nafion matrix through the electrostatic interaction between positive charged Mn ion and negative charged sulfonate end groups in Nafion ionomer. Then after pyrolysis under nitrogen atmosphere, the Nafion ionomers was transformed into carbon frameworks and MnO nano-particles was formed and highly dispersed within them. The formed MnONP@FC was characterized through SEM, TEM and XPS and the electrochemical performances of the hybrid device, which composited MnONP@FC with the porous carbon materials, were also investigated. The results exhibited that this new hybrid supercapacitor showed a high energy density up to 40 mAh g-1, long cycle stability and good rate performance.

Figure 1
Oxysulfide Lialso: A Lithium Superionic Conductor from First Principles
Authors: WANG Xuelong , Xiao Ruijuan , Li Hong , Chen Liquan 
Published: February 2020

Searching for lithium superionic conductors attracts a lot of attention over the past few decades, especially for the development of all-solid-state lithium batterie. So far, the only kinds of solid material with ionic conductivity over 10-2 S/cm at room temperature are among sulfide materials (Li10GeP2S12 and its derivative, Li7P3S11 glass-ceramic, and Li9.54Si1.74P1.44S11.7Cl0.3). However, sulfides generally suffer from high sensitive to moisture and poor stability of solid electrolyte/oxide cathode interfaces. Compared with sulfides, the oxide SEs have significantly better chemical and electrochemical stability, whereas the highest ionic conductivity achieved in them is still one order of magnitude lower than those of liquid electrolytes. To combine the advantages of sulfides and oxides, anion mixing is expected to be a promising strategy to design the lithium superionic conductors with improved stabilities and high ionic conductivity. To the best of our knowledge, there is still no discovery of crystalline oxysulfide for SEs used in lithium batteries.
In this work for the first time we identify a new layered oxysulfide LiAlSO in orthorhombic structure as a novel lithium superionic conductor through first-principles calculations and crystal structure prediction techniques. Two kinds of stacking sequences of AlS2O2 layer are found in different temperature ranges. Phonon and molecular dynamics simulations verify their dynamic stabilities, and wide band gaps up to 5.6 eV are found by electronic structure calculations. The lithium migration energy barrier simulations reveal the collective interstitial-host ion “kick-off” hopping mode with barriers lower than 50 meV as the dominating conduction mechanism for LiAlSO, making it a promising solid state electrolyte in lithium secondary batteries with fast ionic conductivity and wide electrochemical window. This is a first attempt that the lithium superionic conductors are designed by crystal structure prediction method and may help explore other mixed-anion battery materials.

Acknowledgment

We acknowledge the National Natural Science Foundation of China (Grant No. 11234013), ‘‘863’’ Project (Grant No. 2015AA034201), and the Beijing S&T Project (Grant No. D161100002416003) for financial support and the Shanghai Supercomputer Center for providing computing resources. We would like to express our thanks to Prof. Jiawang Hong (Beijing Institute of Technology) for his fruitful discussion.
High Energy Lithium-Ion Battery Using Substituted LiCoPO4
Authors: Liu Dongqiang , Kim Chisu , Cho Myunghun , Guerfi Abdelbast , Zaghib Karim , Delp Samuel A. , Allen Jan L. , Jow T Richard 
Published: February 2020

There is a constant drive to improve the specific energy and energy density of the state-of-the-art lithium-ion battery. High energy can be achieved by either choosing a cathode material that operates at a higher potential or has a higher specific capacity. Compared with the conventional 4-V cathodes such as LiCoO2 (LCO), LiNi
x
Co
y
Al
z
O2 (NCA), LiMn2O4 (LMO) and 3.5-V LiFePO4 (LFP), LiCoPO4 (LCP) operates at 4.8 V (vs. Li/Li+) with a theoretic capacity of 167 mAh g-1, resulting in a specific energy of ~800 Wh kg-1, which is about 25% higher than those of the conventional LFP and LMO lithium-ion batteries. Although Co is more expensive than the other transition metals, the energy cost of LCP is expected to be cheaper than all commercialized lithium-ion batteries on the market [1] due to the improved energy density (FIG.1).
However, LCP suffers from severe capacity fade due to the low intrinsic electronic/ionic conductivity, structure deterioration and electrolyte decomposition [2]. In order to improve the cyclability and reduce the cost of LCP, Co ions were partially substituted by cheaper elements such as Fe, Cr and Si etc [3]. Meanwhile, a carbon-coating was used to improve the electronic conductivity of LCP. Electrochemical tests showed that both carbon-coating and substitution greatly improved the cycling performance of LCP, which suggests that the substituted LCP is a very promising cathode candidate for high energy lithium-ion battery.

References

[1] S. Brutti, S. Panero, ACS Symposium Series, 1140, Chapter 4, 69 (2013).
[2] K. Tadanaga, F. Mizuno, A. Hayashi, T. Minami, M. Tatsumisago, Electrochemistry
71, 1192 (2003).
[3] J. L. Allen, J. L. Allen, T. Thompson, S. A. Delp, J. Wolfenstine, T. Richard Jow, J. Power Sources, 327, 229 (2016).
FIG. 1. Energy density and energy cost of LCP compared with other cathode materials currently used in lithium-ion batteries.

Figure 1
Effects of Irradiation Induced Defects on TiO2 Electrodes for Lithium Ion Batteries
Authors: Smith Kassiopeia , Savva Andreas , Deng Changjian , Wharry Janelle , Hwang Sooyeon , Su Dong , Wang Yongqiang , Xu Tao , Butt Darryl , Hwang Sooyeon , Xiong Hui (Claire) 
Published: February 2020

We are living in a time of growing concerns over population growth, energy consumption, and climate change. These issues are driving the need for advanced electrochemical energy storage (EES) technologies, such as batteries, to support a shift to renewable energy sources. After their commercialization in the 1990’s LIBs have dominated the field of portable electronics, and have become one of the most promising EES systems for renewable energy systems. Even so, the future demands of EES technology will require LIBs to offer increased energy and power density, improved safety, and longer cycle life. As such, recent studies have investigated enhanced electrochemical charge storage in electrodes that contain intentional structural defects.
A new approach to introduce defects in electrode materials is to use ion irradiation to produce damage cascades which result in point defects in the target material. The objective of this work is to investigate the fundamental effects of irradiation on nanostructured TiO2, and to understand how these effects can alter the electrochemical charge behavior when the oxide is used as an electrode in Li-ion batteries. Our work suggests that tailoring the defect generation through ion irradiation within metal oxide electrodes could present a new avenue for design of advanced electrode materials.
In this study, we first focus on separating the effects of irradiating species on defect production by conducting proton, niobium, and nickel irradiations on [100] and [110] rutile TiO2 single crystals. We then extend our study to nanostructured TiO2, irradiated with protons. After room temperature irradiation the nanotubes undergo an irradiation-induced phase transformation accompanied by a 35% reduction in capacity compared to anatase TiO2. On the other hand, proton irradiation at 250 °C induced a disordered rutile phase which along with a 20% increase in capacity. Voltammetric sweep data was used to determine the contributions from diffusion-limited intercalation and capacitive processes and it was found that the electrodes after irradiation has more contributions from diffusion in lithium charge storage. Our work suggests that tailoring the defect generation through ion irradiation within metal oxide electrodes could present a new avenue for design of advanced electrode materials.

Figure 1
Finite Element Simulation of the Coreactant Electrogenerated Chemiluminescence Mechanism
Authors: Danis Andrew , Odette William L , Perry Samuel C , Canesi Sylvain , Sleiman Hanadi F , Mauzeroll Janine 
Published: February 2020

Electrogenerated chemiluminescence (ECL) is an electron transfer between redox products formed at an electrode that results in the formation of an excited state species, which is capable of photon emission. This excited state can be achieved by a reaction between an oxidized and a reduced form of the same luminophore, or via the reaction of the oxidised or reduced luminophore with an electrochemically generated co-reactant. This is of great interest to the biosensing community, as the attachment of multiple ECL-active luminophores to a target molecule is a very attractive signal amplification strategy. This is a complicated process involving multiple reaction steps, and so a thorough understanding of the complete reaction process and the evolution of the excited state luminophore is essential.
In order to gain a greater understanding of the ECL mechanism, we use finite element digital simulations to explicitly model each reaction step. This was done for an organometallic ECL standard, tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)3
2+), and tripropylamine (TPA), where the simultaneous oxidation of Ru(bpy)3
2+ and TPA result in the generation of the excited state Ru(bpy)3
2+*. The geometry and reaction conditions were chosen to match experimental data from our previously developed cuvette based system. Comparison of simulated voltammetry and ECL emission both agreed well with the experimental data, validating the experimental results and also giving insight into the impact of the confined cuvette geometry on the observed voltammetry. Investigations into the simulated concentration profiles also revealed the ECL emission to be confined close to the electrode surface, and so the impact of side reactions at the counter electrode could be omitted. Importantly, each step in the ECL process could be individually analysed and quantified in order to provide a greater understanding of the mechanism as a whole.
Figure 1: A) Simulated concentration of the excited state luminophore Ru(bpy)3
2+* at the position of peak ECL emission. B) Comparison of the experimental ECL emission peak with the simulated concentration of Ru(bpy)3
2+*, showing good agreement.

Figure 1
Electrocatalytic Reduction of Carbon Dioxide at Network Films of Metallic Centers Generated within Supramolecular Ligands
Authors: Wadas Anna , Frik Malgorzata , Rutkowska Iwona Agnieszka , Kulesza Pawel J 
Published: February 2020

The catalytic reductive transformation of carbon dioxide (CO2) to fuels and commodity chemicals is one of the most important contemporary energy and environmental challenges. Because CO2 is very stable, the direct electroreduction of CO2 to CO requires large over-potentials. Different approaches to electrocatalytic reduction of CO2 have been reported previously.
Copper is commonly considered out of the majority of metals, and it has often been studied in aqueous solutions. Among important issues is that it induces the cleavage of the C-O bonds in CO2 and it allows the formation of highly reduced products. Due to the unique properties of Cu toward CO2 reduction, systems in which this is employed have received the greatest degree of interest with respect to the catalytic effects in aqueous and organic electrolytes. In this work, CO2 reduction was investigated in the presence of new copper complex, in addition to the parallel studies on bimetallic copper-gold complex with the particular focus on the roles of particular metallic centers on the catalyst activity for the carbon dioxide reduction reaction..
A rotating ring (platinum)-disk (glassy carbon) electrode is employed for the characterization of different catalysts during CO2-electroreeduction in aqueous solutions.
In the process of electrochemical reduction of carbon dioxide, we have also concentrated on the catalytic system yielding nanostructured metallic palladium via reduction of the complex of palladium(II), [Pd(C14H12N2O3)Cl2]2∙MeOH. The catalytic activity of CO2 reduction was estimated from the oxidation charge of the adsorbed products. The adsorbed products obviously interfere with the formation of the oxide film on the Pd surface.
Mechanistic considerations will be a subject of our interest too. The results of XPS and IR studies will be used o comment on the surface identity of palladium based catalysts and possible reaction pathways.
(Invited) Photo-Electrochemical CO2 Reduction on Composite Metal and Metal-Oxide Cathodes
Authors: Augustynski Jan , Solarska Renata 
Published: February 2020

Following the first report by Hori et al.1 that demonstrated ability of Group IB (11) based metal cathodes – copper, silver and gold – to promote electro-reduction of CO2 to gaseous products, substantial work has been subsequently devoted to the question of the electrodes deactivation occurring over prolonged electrolysis runs. Although the deactivation affects both an Au and an Ag cathode, where the CO2 reduction leads to the formation of CO, the most severe poisoning occurs in the case of the Cu where production of hydrocarbons (CH4, C2H4) and ethanol is practically suppressed after less than 1 h of electrolysis and become replaced by H2 evolution. SERS measurements conducted during electro-reduction of CO2 on the Cu surface suggest formation of a mixture of copper oxide/hydroxide and carbonate species as being the reason of the observed electrode deactivation. Among the means allowing activation of the cathodes are: short periodic potential cycling, implementation of composite (metal alloy, metal/oxide) electrodes, incorporation into the cathode of plasmonic metal nanostructures. Notably, it was in the case of the roughen silver electrode that the plasmon decay-induced CO2 reduction has been demonstrated for the first time2.
1. Y. Hori, K. Kikushi, S. Suzuki, Chem. Lett. 1695 (1985).
2. J. Augustynski, K. Bienkowski, R. Solarska, Coord. Chem. Rev. (2016).
Bio-Electrocatalytic CO2 Reduction into Formate Using Metal-Independent Formate Dehydrogenase from Candida Boidinii (Yeast)
Authors: Jayathilake Buddhinie Srimali , Narayanan S. R. 
Published: February 2020

Rising levels of carbon dioxide (CO­2) in the atmosphere is a leading cause for global climate change. To reduce the level of CO2 in the atmosphere, the reduction of carbon dioxide into useful organic compounds and fuels is attractive. However, due to the inertness and stability of carbon dioxide molecule, the electro-reduction of carbon dioxide is not facile. Formate is the first stable intermediate in the electrochemical reduction of carbon dioxide. Further, formic acid is useful as a chemical feedstock, a fuel, and an efficient carrier of hydrogen.1-2 The production of formate is expected to be facile compared to that of other organic compounds as it involves the formation of just a C-H bond without dissociation of the strong C-O bond.
We have studied the interconversion of CO2 and formate using metal-independent type enzyme, Formate Dehydrogenase (FDH) derived from the yeast Candida boidinii. This enzyme relies on cofactors such as nicotinamide adenine dinucleotide phosphate (NAD(P)+/ NAD(P)H). To achieve steady-state electrolysis, we have examined the continuous electrochemical regeneration of the reduced form of NAD(P) cofactor. However, we find that formation of an inactive-stable dimer of NAD is a major obstacle to continuous electrolysis. Thus, we have focused on using methyl viologen (MV) as an artificial co-enzyme in conjunction with FDH. MV has the advantage of not being de-activated upon re-generation and also prevents the re-oxidation of formate to carbon dioxide.3

MV in its reduced form was synthesized in a three-electrode system using Toray paper working electrode, platinum counter electrode and Ag/AgCl reference electrode at 0.45 V vs NHE. The concentration of MV in its redox states was followed by scanning voltammetry using a carbon fiber microelectrode (Figure 1). CO2reduction to formate by the reduced form of the MV in the presence of FDH was investigated in this study. Formate production was confirmed by NMR. The presentation will discuss effect of enzyme concentration, carbon dioxide source and pH on the rate of production of formate.
Acknowledgement:
Authors acknowledge Loker Hydrocarbon Research Institute and University of Southern California for financial support of this work.
Refernces:
1.Olah, G. A.; Goeppert, A.; Prakash, G. S., Beyond oil and gas: The Methanol Economy. John Wiley & Sons: 2011.
2.Narayanan, S.; Haines, B.; Soler, J.; Valdez, T., Electrochemical conversion of carbon dioxide to formate in alkaline polymer electrolyte membrane cells. Journal of The Electrochemical Society
2011,
158(2), A167-A173.
3.Noji, T.; Jin, T.; Nango, M.; Kamiya, N.; Amao, Y., CO2 Photoreduction by Formate Dehydrogenase and a Ru-Complex in a Nanoporous Glass Reactor. ACS Applied Materials & Interfaces
2017,
9 (4), 3260-3265.

Figure 1
Factors That Limit the Performance of CO2 Electrolyzers
Authors: Yang Hongzhou , Liu Zengcai , Sajjad Syed D. , Gao Yan , Kaczur Jerry J. , Masel Rich 
Published: February 2020

Carbon dioxide (CO2) electrolysis provides a pathway to turn waste CO2 into valuable fuels and chemicals but most previous efforts demonstrate low selectivity, high overpotential and low rates for the targeted products. In recent work Dioxide Materials has been using Sustainion™ imidazolium functionalized membranes and ionomers to improve the performance. Runs at a fixed current density of 200 mA/cm2 showed that one can maintain 98% selectivity for six months at about 3 V applied potential, with a voltage increase of only 5 µV/hour. Other runs showed stable performance at 400 and 600 mA/cm².
Present areas for improvement of the technology include a better understanding of the processes that are occurring on the cathode catalysts, improving response to process upsets, developing cell designs that can be scaled to the m2 size and alternates to iridium as an anode catalyst. Initial work on these issues will be discussed.