bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advanced Na[Ni0.25Fe0.5Mn0.25]O2/C Cathode / EMS Electrolyte / Fe3O4 Anode for Sodium-Ion Batteries
Authors: Hwang Jang-Yeon , Oh Seung-Min , Myung Seung-Taek , Yoon Chong seung , Lu Jun , Amine Khalil , Sun Yang-Kook 
Published: February 2020

Lithium is an attractive battery material because it is the lightest metal, but its resources are concentrated in large quantities mainly in South America with an associated risk of dependence on a single geographic area.1 In addition, the price of lithium-ion batteries is affected by the high cost of their active materials, commonly based on cobalt compounds. As a result, there is an increasing interest worldwide in developing low cost and sustainable energy storage systems that do not use lithium or cobalt. Among them, rechargeable sodium batteries, due to the almost infinite supply of the metal, are the most appealing as immediate alternatives to lithium batteries. Recently reported results2-4 have triggered an increasing industrial and academic interest in sodium-ion batteries operating at room temperature. Pioneering work by Hagenmuller et al. and Yamamoto et al. introduced O3-type NaMO2 (M = Ni, Co, and Fe) in which Na+ could be inserted into a host structure. Since then, interest in developing sodium batteries declined because of the fast development and market domination of lithium-ion batteries. However, recent increasing demands for low-cost energy storage have renewed interest in sodium-based batteries and, accordingly, the O3 type NaMO2 compounds are being revisited as a cathode material due to the facile synthesis and structural stability, including Na-Ni0.5Mn0.5O2, NaCoO2, NaCrO2, NaMnxM1
−
xO2 (M =Co, Ni), Na[Ni1/3Fe1/3O1/3]O2, and NaxVO2. At present, the electrochemical performance of these cathode materials has been limited due to the lack of electrolytes capable of withstanding voltages above 3.9 V versus Na/Na+. In response, we have developed a sodium-ion battery that has an electrolyte of NaClO4 in a mixture of ethyl methanesulfonate electrolyte (EMS) and fluoroethylene carbonate (FEC) additive for increasing the stability and conductivity, along with an anode of carbon-coated Fe3O4 and a cathode of O3-type layered Na[Ni0.25Fe0.5Mn0.25]O2. The electrolyte is a key component if sodium-ion batteries are to become competitive with or surpass lithium-ion batteries. The main requirement is a wide anodic stability window in order to allow complete desodiation of the cathode. A common choice has been 1 M sodium perchlorate in propylene carbonate (NaClO4−PC) with selected additives. For instance, as suggested by Komaba et al., the addition of a small amount of FEC to the PC-based solvent contributes to improved cycleability of sodium batteries, possibly because of a positive effect induced by the fluorination of the anode surfaces.
(1) Scrosati, B.; Garche, J. J. Power Sources 2010, 195, 2419−2430.
(2) Fouassier, C.; Matejka, G.; Reau, J.-M.; Hagenmuller, P. J. Solid State Chem. 1973, 6, 532−537.
(3) Delmas, C.; Fouassier, C.; Hagenmuller, P. Physica B+C 1980, 99,81−85.
(4) Braconnier, J.-J.; Delmas, C.; Fouassier, C.; Hagenmuller, P. Mater. Res. Bull. 1980, 15, 1797−1804.
Surface Coating of 5V Spinel LiNi0.5Mn1.5O4 Cathodes By Carbon Materials for Li-Ion Batteries Applications
Authors: Hwang Taejin , Lee Jieun , Noh Hana , Lee Jeongyeon , Mun Junyoung , Lee Joong-Kee , Choi Wonchang 
Published: February 2020

Introduction

As applications of Lithium ion batteries (LIBs) are focused, high energy density active materials are needed. Therefore, LiNi0.5Mn1.5O4(LNMO) is one of the promising active materials for LIBs because of it has high working voltage about 4.7 V and good cyclability. Carbon coating is one of the best methods to prevent surface side reactions of electrolyte. However, oxide cathode materials are usually synthesized at high temperature, so that carbon coating is limited because carbon can be oxidized easily. To overcome this problem, we performed re-oxidized process to make RO-MWCNTs. We expected this can assign resistivity against oxidation to MWCNTs. Continually, RO-MWCNTs are coated on LNMO by solid-state coating method. Several electrochemical tests have performed to identify effects of RO-MWCNTs coating on LNMO powder.

Experimental

To prepare RO-MWCNTs, pristine MWCNTs were reduced at 900℃ for 6 hours under Ar gas which contains 5wt% of H2. Reduced MWCNTs are re-oxidized at 300℃ for 2 hours. As prepared MWCNTs and RO-MWCNTs have coated 1wt% on LNMO by the solid-state coating at Hosokawa. Proportion of coated materials were specified by TGA and EA. Electrode slurry has been made of 96% of active materials, 2% of Denka black, 2% of PVdF in NMP solvent. Total amounts of conductive materials and coated MWCNTs are fixed for 2%. The slurry was casted on Al foil for current collector and assembled with 2032 coin cell.

Results and discussion

Figure 1. shows rate capability test of pristine, MWCNTs coating, RO-MWCNTs coating LNMO samples. C-rates were changed at various rates. According to rate capability test result, RO-MWCNTs coating has improved electrical conductivity of electrode.
Figure 2. shows cyclability test of samples which had been stored at 60℃ oven for 7 days. We could observe RO-MWCNTs coated sample has much better capacity retention than MWCNT coated and pristine samples. We could identify that re-oxidized process have affected MWCNTs to resist against oxidation at high voltage.

Figure 1
Surface Modification of Silicon-Based Alloy Materials for Lithium-Ion Battery Applications
Authors: Yang Hwi Soo , Kim Sang-Hyung , Kim Seon-Kyong , Park Cheol-Ho , Kim Dong-Won 
Published: February 2020

Lithium-ion batteries have been considered as a promising power source for electric vehicles and energy storage systems, due to their high energy density and long cycle life. In order to further increase the energy densities of lithium-ion batteries, it is essential to improve the specific capacity of active electrode materials. It has been well known that the silicon-based anode materials have an extremely high theoretical capacity. However, the main problem of silicon-based anode materials is high volume expansion during cycling, which leads to the loss of electrical contacts and poor capacity retention. To solve these issues, many studies have been carried out in terms of thin film, nanostructure, alloy and composites. The capacity fading is known to be closely related to the interfacial instability of the Si-based electrodes. In this study, we report synthesis and electrochemical characterization of Si-based alloy materials for high energy density lithium-ion batteries. Furthermore, we modified their surface to form stable interfacial layer and obtain good capacity retention. Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and galvanostatic cycling test.
Atomistic Simulation Studies of the Electrochemical Activity in Nanocrystalline Li2MnO3
Authors: Ngoepe Phuti Esrom , Sayle Thi X T , Sayle Dean C 
Published: February 2020

Layered-layered oxide composite cathodes, typically of composition xLi2MnO3·(1−x)LiMO2, have attracted much attention, for essentially doubling the capacity available in the earlier generation of Li-ion batteries based on LiCoO2 [1]. However, their use is currently limited by, amongst others, voltage fade [2]. Hence, further studies on one of the end members of the composites, Li2MnO3, could shed valuable insights on such problems.
Li2MnO3 is known to be electrochemically inactive in the parent bulk form and can be rendered Li-active by leaching Li or Li2O from the structure; these Li-deficient compounds are reported to have high intercalation capacities and good reversibility [3]. Alternatively, when synthesized in a nanocrystalline form, Li2MnO3 has been shown to be electrochemically active, yielding capacities up to 200 mAh/g, and excellent capacity retention over multiple cycles [4].
In the current study simulated amorphisation recrystallisation method [5] is used to nucleate and crystallise ternary nanoparticle of Li2MnO3. Simulations of the charging of Li2MnO3 reveal that the reason nanocrystalline- Li2MnO3 is electrochemically active, in contrast to the parent bulk- Li2MnO3, is because in the nanomaterial the alternating Li planes are held apart by Mn ions, which act as a pseudo ‘point defect scaffold’. The Li ions are then able to diffuse, via a vacancy driven mechanism, throughout the nanomaterial in all spatial dimensions while the ‘Mn defect scaffold’ maintains the structural integrity of the layered structure during charging. Our findings reveal that oxides, which comprise cation disorder, can be potential candidates for electrodes in rechargeable Li-ion batteries.
References
[1] Thackeray, M.M., Johnson, C.S., Vaughey, J.T. Li, N. and Hackney, S.A., J. Mater. Chem. 15, 2257, 2005.
[2] Croy J.R., Gallagher K.G., Balasubramanian M., Long B.R. and Thackeray M.M., J. Electrochem. Soc. 161, A318, 2014.
[3] Thackeray M. M. Progr. Solid State Chem. 25, 1, 1997.
[4] Jain, G.R., Yang, J.S., Balasubramanian, M. and Xu, J.J., Chem. Mater. 17, 3850, 2005.
[5] P.E.Ngoepe, R.R. Maphanga and D.C. Sayle, (2013), “Towards the Nanoscale”, Chapter 9 in Computational Approaches to Energy Materials, pp 261-290, edited by C.R.A. Catlow, A. Sokol and A. Welsch, John Wiley and Sons Ltd.
Improvement of Interfacial Properties of Sulfide Based All-Solid-State Lithium Secondary Batteries with Li-Si Alloy Anode
Authors: Jin Joo Sung , Park Hye Won , Lim Hyung-Tae 
Published: February 2020

Li22Si5 alloy powder was synthesized by mechanical alloying and its electrochemical performance was investigated for use in solid-state battery anodes. Using these anode materials, all-solid-state lithium batteries were assembled with Li4Ti5O12 (LTO) or titanium disulfide (TiS2) as cathode and Li2S-P2S5 as electrolyte. Galvanostatic charge/discharge tests were also performed, and capacity was increased about two times by the additional powder milling process with gradient sturucure, which is consistent with the impedance results. Thus, the results from the present work indicate that using the secondary milling process to refine the electrode powder and gradient structure to reduce interfacial resistance are effective ways to increase the kinetics of alloying and de-alloying with higher utilization of anode active material in all-solid-state lithium secondary batteries.
Degradation of Cobalt Oxide Anode for Lithium Batteries at High Conducting Material Content
Authors: Choi Woo-Sung , Chang Wonyoung , Shin Heon-Cheol 
Published: February 2020

Cobalt oxide is considered as promising option for the anode material in next generation rechargeable lithium battery thanks to its large specific capacity (~900 mAh/g). However, its low electrical conductivity causes poor energy efficiency and decreased power density. In order to lower the electrode resistance, many researchers have performed their experiments using the cobalt oxide anode containing large amount of conducting material. On the other hand, the overgrowth of the solid electrolyte interphase (SEI) layer on the cobalt oxide surface and the resulting decrease in specific capacity and energy density are another key issue for its practical use. Specifically, it has been known that the active materials move away from its original position to the overgrown SEI layer during the repetitive charge-discharge cycling and is gradually lost. Accordingly, the larger is the quantity of the SEI layer, the greater is the decrease in the specific capacity.
In this work, we report that the larger amount of conducting material in the cobalt oxide anode leads to its faster degradation during the operation. From the microscopic observation and porosity measurement of the pre- and post-cycled samples with different conducting material contents, it is proved that the free volume in the electrode decreases as the content of conducting material is raised. Furthermore, the analysis of the change in cumulative irreversible capacity loss during charge-discharge cycles shows that the high content of the conducting material promotes the growth of the SEI layer.
In order to further investigate the character of the SEI layers formed at different conducting material contents, the SEI layer formation is mathematically modeled on the basis of the Butler-Volmer relation. By fitting the model to the experimental data, a few physical parameters of the SEI layer can be successfully determined. In particular, from the calculation it is confirmed that the resistivity of SEI layer is considerably changed with the conducting material content. This implies that the incorporation rate of metallic cobalt in the SEI layer during cycling might be critically dependent on the conducting material content.
In this presentation, the optimal content of conducting material is discussed from the viewpoint of cycling stability and rate capability. Furthermore, the validity of the model for the systems used in this work is addressed by an analysis of fitting accuracy.
In Situ High Resolution Synchrotron X-Ray Powder Diffraction Studies of Lithium Batteries
Authors: Amri Mahrez , Fitch Andy , Norby Poul 
Published: February 2020

Lithium ion battery technology is the heart in operating modern technology devices such as mobile phones and laptops. However, as our society is moving towards the utilization of sustainable energy sources, batteries can be foreseen to become an even more important part of the energy infrastructure. They will be used not only for transportation, but also for medium and short term storage as well as for frequency stabilization in intermittent grid scale energy sources such as solar and wind. Thus, the development of new cheaper and safer battery materials with high energy and power density is very important for a successful worldwide energy transition.
The understanding of structural and compositional changes of bulk electrodes in batteries is undoubtedly important. However, it is often transport of electrons and ions across and through interfaces [1] (e.g., between lithiated and delithiated domains) which limits the obtainable power density and battery life time. A challenging and important task is to obtain in situ information about the formation and evolution of interfaces in an operating battery system. This work addresses these challenges and for this purpose we have developed a special microcapillary battery cell allowing diffraction information to be obtained from only the active material during battery operation [2]. High resolution synchrotron x-ray powder diffraction technique has been undertaken to obtain detailed structural and compositional information during lithiation/delithiation of commercial LiFePO4 materials [3].
We report results from the first in situ time resolved high resolution powder diffraction experiments at beamline ID22/31 at the European Synchrotron Radiation Facility, ESRF. We follow the structural changes during charge of commercial LiFePO4 based battery materials using the Rietveld method. Conscientious Rietveld analysis shows slight but continuous deviation of lattice parameters from those of the fully stoichiometric end members LiFePO4 and FePO4 indicating a subsequent variation of stoichiometry during cathode delithiation. The application of an intermittent current pulses during charge using GITT technique shows an oscillation of lattice constants that correlates with the applied current and electrochemical relaxation sequence and may indicate the existence of metastable non-stoichiometric states.

References

[1] R. Malik, F. Zhou, and G. Ceder, Nat. Mater., 10, 587 (2011).
[2] R. E. Johnsen, and P. Norby, J. Appl. Crystallogr., 46, 1537 (2013).
[3] A. K. Padhi, K. S. Nanjundaswamy, and J. B. Goodenough, J. Electrochem. Soc., 144, 1188 (1997).
Dynamic Structures of the Active Sites in Iron-Based Catalysts during ORR
Authors: Jia Qingying , Strickland Kara , Mukerjee Sanjeev , Hafiz Hasnain , Bernardo Barbiellini-Amidei , Tylus Urszula , Ramaswamy Nagappan 
Published: February 2020

The prohibitive cost of platinum catalysts for accelerating the sluggish oxygen reduction reaction (ORR) severely hampers the commercialization of fuel cells. Despite recent progress in developing highly active non-precious catalysts (typically Fe−Nx−C) as promising alternatives to Pt, a less empirical synthesis approach is still missing due to the lack of fundamental understanding of the nature of the active sites, as well as their structural effects on ORR activity.
Herein, the structural and electronic properties of iron meso-tetraphenylporphine chloride (FeTPPCl) pyrolyzed under various temperatures, as well as the state-of-the-art polyaniline (PANI)-derived catalyst [1] are probed using in situ x-ray absorption spectroscopy (XAS) in combination with ab initio calculations. Three Fe2+−N4−like active sites with distinct Fe displacement are identified. All the active sites undergo Fe2+/Fe3+redox transition that triggers the adsorption of hydroxyl intermediate (OH*) from water activation, but they exhibit distinctly different Fe-N switching behavior during ORR, which accounts for their different ORR activities.

Acknowledgements:
The PANI-derived catalysts were prepared and provided by Gang Wu and Piotr Zelenay (Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545). Use of the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), was supported by the U.S. Department of Energy, Office of Basic Energy Sciences. This publication was made possible by the Center for Synchrotron Biosciences grant, P30-EB-009998, from the National Institute of Biomedical Imaging and Bioengineering (NBIB). Support from beamline personnel Dr. Erik Farquhar and Mark Chance (X3B) are gratefully acknowledged.

References

(1) Wu, G.; More, K. L.; Johnston, C. M.; Zelenay, P. Science
2011, 332, 443-447.
(Invited) Separator Requirements for Nonaqueous Flow Batteries
Authors: Darling Robert M. 
Published: February 2020

Energy storage is increasingly viewed as a potentially valuable asset for electricity grids composed of high fractions of intermittent sources, like wind turbines, or unreliable generation and transmission services. Flow batteries are a candidate technology for large-scale, long duration storage of grid energy. Both aqueous and nonaqueous technologies are being researched and technical progress is being made on both fronts. The separator between the positive and negative electrolytes is a key technology that must be addressed in both cases. Nonaqueous electrolytes are generally less conductive than aqueous electrolytes, and the degree to which this can be tolerated in light of higher expected operating voltages needs to be understood. We use techno-economic modeling to establish ranges of separator properties that are required to attain economic viability for nonaqueous flow batteries and compare these to the properties required for aqueous cells.
Activation of Platinum-Based Centers through Modification with Metal Oxo Species toward Electrocatalytic Oxidation of Dimethyl Ether and Methanol
Authors: Rutkowska Iwona Agnieszka , Sek Jakub P. , Marks Ewelina , Zelenay Piotr , Kulesza Pawel J 
Published: February 2020

We have considered nanonstructured metal oxides as promoters for platinum, palladium or bimetallic platinum-ruthenium nanoparticles to fabricate electrocatalytic systems capable of efficient oxidation of dimethyl ether, a potentially new fuel of importance to low temperature fuel cells. The research has been performed in comparison to methanol. We explore the fact that certain inorganic oxides (e.g. WO3, TiO2, ZrO2 and CeO2) and polyoxometallates of molybdenum or tungsten tend to influence supported metal centers in ways other than simple dispersion over electrode area. Among useful characteristics of metal oxides and related systems are the following: they can generate –OH groups at low potentials that induce oxidation of passivating CO adsorbates (e.g. on Pt); they can potentially break C-H bonds (e.g. by hydrogen tungsten oxide bronzes); and they can possibly weaken C-O bonds during dimethyl ether oxidation (e.g. through changes of the electronic properties of Pt or Pd as additional component). Also nanostructured gold in combination with platinum has been demonstrated to enhance the overall electrocatalytic performance during oxidation of such small organic molecules as methanol and dimethyl ether.
We pursue a concept of utilization of functionalized titanium dioxide, tungsten oxide and/or zirconium oxide matrices (by admixing them with polyoxometallate-modified gold nanoparticles) for supporting and activating noble metal nanoparticles (Pt, Pt-Ru, Pd, Pt-Pd) toward electrooxidation of dimethyl ether in comaprison to methanol. Remarkable increases of the respective electrocatalytic currents measured under voltammetric and chronoamperometric conditions have been observed. The most likely explanation takes into account improvement of overall conductivity (due to the presence of nanostructured gold) at the electrocatalytic interface (formed by metal oxide support), as well as and possibility of specific Pt-metal oxide or Pt-Au electronic interactions and existence of active hydroxyl groups on transition metal oxo species.in the vicinity of catalytic Pt sites. Further, the capping layers of Keggin-type phosphomolybdates, which are known to undergo fast stepwise multi-electron redox processes as well as to activate Pt-based electrocatalysts, may also contribute to the overall enhancement effect.
Sustainable Electrochemistry: From Lignin Processing to Paired Electrolysis Reactions
Authors: Nguyen Bichlien H. , Perkins Robert J , Smith Jake A. , Moeller Kevin D 
Published: February 2020

When evaluating the sustainability of an electrochemical synthesis, the source and efficient use of electricity, the generation of waste byproducts, and the source of chemicals used should be considered in the development of a greener process.
Constant current electrochemical oxidation reactions increase functionality of a molecule but are limited in scope based on oxidation potential. This shortcoming disappears when using a chemical oxidant, which can select based on steric hindrance, chirality, chelation control, and other factors. However, a major pitfall of any stoichiometric chemical oxidation reaction is the generation of a stoichiometric reduction byproduct, oftentimes a metal waste product. To circumvent this problem, chemical oxidants can be recycled directly at the anode while generating only H­2 gas at the cathode and can be powered by a simple photovoltaic power supply.1,2

From a green chemistry standpoint, the substrates used in anodic oxidations should have their origins from renewable feedstocks. Lignin, a biopolymer found in wood, has been disassembled into small monomers and converted into substrates for synthesis of heterocyles and quinones.3 Ideally, to maximize efficiency of these and other electrochemical processes, one wants to perform a useful oxidation at the anode simultaneously with a useful reduction at the cathode. Using this idea of a paired electrolysis, electrochemical oxidation of lignin-derived substrates has been coupled with CO2 reduction.
In this presentation, the recycling of a variety of chemical oxidants at an electrode using simple photovoltaics as the source of electricity will be discussed. Furthermore, breakdown of lignocellulosic biomass into chemical building blocks for use in paired electrolyses will be explored (Figure 1).
References:

Nguyen, B. H.; Redden, A.; Moeller, K. D. “Sunlight, Electrochemistry, and Sustainable Oxidation Reactions.” Green Chem.
2014, 16, 69-72.

Anderson, L. A.; Redden, A.; Moeller, K. D. “Connecting the Dots: Using Sunlight to Drive Electrochemical Oxidations.” Green Chem.
2011, 13, 1652-1654.

Unpublished results with Robert Perkins, Jake Smith and Kevin Moeller.

Figure 1