bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Electrochemical Performance of Lithium-Sulfur Batteries Using a Modified Separator Coated with Ca(OH)2 and Acetylene Black
Authors: Shao Hongyuan , Huang Yaqin 
Published: February 2020

Abstract

Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation energy storage devices, owing to the extremely high theoretical specific capacity and energy density of sulfur. However, the shuttle effect of lithium polysulfide hampered its commercial application. Recently, more and more attentions have been focused on designing the modified separator with physical and chemical absorption of polysulfide.
In this work, Ca(OH)2 and acetylene black (AB) had been successfully used to design a functional separator for Li-S batteries. The results indicated that Ca(OH)2-AB coated separator could effectively constrain the shuttle effect of polysulfides. In Figure 1, the first upper plateau discharge capacity is 410 mA h g-1 approaching 97.8% of the theoretical value (419 mA h g-1) after coating Ca(OH)2 and AB into common separator, indicating that the polysulfide diffusion is effectively limited. After 100 cycles, the batteries with Ca(OH)2-AB coated separator remains 82.3% of the theoretical value, while the batteries with AB coated and common separators only retain 65.6% and 38.7%. The enhanced upper plateau capacity demonstrates that Ca(OH)2 can effectively trap the polysufides and inhabit the shuttle effect.
Acknowledgements
Financial support from the National Science Foundation of China (No. 51272017) is gratefully appreciated.

Notes

a

State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical University of Chemical Technology, Beijing 100029,
People’s Republic of China.

* E-mail: huangyq@mail.buct.edu.cn; Fax: +86 10 6443 8266; Tel: +86 10 6443 8266.

Figure 1. Upper plateau discharge capacities of batteries employing different separators.

Figure 1
Effect of Aging on the Mechanical Properties of Li-Ion Cell Components
Authors: Cao Lei , Zhang Chao , Santhanagopalan Shriram , Pesaran Ahmad 
Published: February 2020

Lithium-ion batteries have been widely used as excellent energy storage devices for many applications, recently in development of electric vehicles (EVs). Challenges in both material and mechanical stability inside battery cells/packs have to be overcome to meet an expected EV lifetime of 10-15 years, which requires up to 3000 deep cycles for battery cells and packs, in addition to the safety requirements.[1] Here we present the results from a systematic investigation combining experimental and modeling approaches to compare mechanical integrity of fresh and aged cell components. Samples were collected from two identical commercial cells containing graphite anode and lithium-nickel-cobalt-manganese oxide cathode, with and without 3000 1C/1C cycles at 45 oC. Mechanical response was measured for the anode, cathode and separator using tensile and compression tests. This data set was used to extract constitutive properties of the individual layers, using an approach we published recently.[2] Implications for electrochemical performance of the cell will be discussed.
References:
1. T. Nagaura, K. Tozawa, Progress in Batteries and Solar Cells 9 (1990) 209-217.
2. C. Zhang, S. Santhanagopalan, M.A. Sprague, A. Pesaran, J. Power Sources 290 (2015) 102-113.
Electrochemical Deposition of MoS2 Thin Films for Energy Storage Applications
Authors: Falola Bamidele Daniel , Suni Ian Ivar 
Published: February 2020

Energy storage addresses the problem of sustainability for renewable but intermittent energy sources like solar, wave and wind power. Electrochemical supercapacitors represent a new technology that helps meet the demands for high power and energy density for the optimal storage of renewable but intermittent energy sources. For inclusion in supercapacitors, transition metal oxide and sulfide electrodes such as RuO2, IrO2, TiS2, and MoS2 exhibit rapid faradaic electron–transfer reactions combined with low resistance.
The pseudocapacitance of RuO2 is about 720 F/g and is 100 times greater than the double-layer capacitance of activated carbon electrodes. However syntheses of these oxide and sulfide electrode materials can be expensive and are not presently in commercial use. We report cathodic electrodeposition of molybdenum disulfide onto glassy carbon electrodes from electrolytes containing 10 mM (NH4)2MoS4 and 0.2 M KCl. Four minutes of electrodeposition yields compact 1 µm thick MoS2 film deposit, as confirmed by SEM/EDX analysis, whereas longer deposition times yields much thicker MoS2 film but with nanoscale cracks.
The film capacitance is studied as a function of bulk film thickness and crystallinity. X-ray diffraction analysis demonstrates crystallization of MoS2 after annealing in Ar at 600°C for 1 hr. The electrochemical performance of both amorphous and crystalline MoS2 films is studied in 1 M TEA-BF4 in acetonitrile by electrochemical impedance spectroscopy, cyclic voltammetry and chronocoulometry. The films demonstrate stable pseudocapacitive behavior; for both the amorphous and annealed films, with specific capacitances of 40 F/g and 300 F/g, respectively. Studies as a function of MoS2 thickness demonstrate that the capacitance eventually plateaus’, suggesting that only the near-surface region is available for charge storage. Results will also be presented for electrochemical impedance spectroscopy and atomic force microscopy of these films before and after capacitance cycling.
Incremental Impedance Technique for Determining Optimal Capacity Control Limits in C-Si Composite Batteries
Authors: Blaser Rachel , Murray Daniel , Karulkar Mohan 
Published: February 2020

It is well known that limiting the cycling SOC of a battery material leads to improved cycle life.1 Determining optimal cycling limits, however, can be an expensive trial-and-error process. Candidate voltage or capacity limits must be proposed and tested, with tests consisting of capacity face measurements over large numbers of cycles, perhaps even at various cycling rates. A more efficient method is to identify a quantifiable phenomenon that manifests early in a cell’s cycle life, and which accurately indicates an SOC range for optimal cycling. In the current work, we use an Incremental Impedance technique to identify critical impedance jumps that serve as markers for optimal SOC limits, detectable from a cell’s very first post-break-in cycle.
To determine an optimal SOC (“Capacity Control”) range for cycling, a five-cycle Incremental Impedance scan was conducted on in-house C-Si anodes, formulation A (PVDF binder, 5 mg/cm2 loading). Figure 1 shows a distinct jump in impedance was observed at 70% SOC during lithiation, and indicates 0-70% as a promising SOC range for cycling.
Based on the Incremental Impedance analysis, cycling was done with SOC cutoffs of 60, 80, and 100%, to probe around the 70% point. Figure 2 shows a 60% SOC cutoff improves cycle life over 80%, while 80% and 100% (full cycling) display similar fade characteristics. 70% SOC is thus a key “point of no return” for SOC limiting.
The technique was repeated for formulation B (CMC/SBR binder, 2 mg/cm2 loading). Results in Figure 3 show that both produce the same sharp increase in impedance at 70%, independent of binder type and loading.
______________________________________________________

1Mohan Karulkar, Rachel Blaser, Bob Kudla, Automotive assessment of carbon–silicon composite anodes and methods of fabrication, Journal of Power Sources, Volume 273, 1 January 2015, Pages 1194-1201

Figure 1
The Effect of a-Site and B-Site Substitution on BaFeO3-δ: An Investigation As a Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cells
Authors: Wang Jian , Ciucci Francesco 
Published: February 2020

Solid oxide fuel cells (SOFCs) are widely thought to be among the most promising energy conversion devices due to their low environmental impact, high efficiency and fuel flexibility. BaFeO3-δ
(BFO) stands out as one of the most electrochemically active iron-based SOFC cathodes. This work systematically investigates the effects of single A-site dopant (5 mol% La3+, Sm3+ and Gd3+) and single B-site dopant (5 mol% Zr4+ and Ce4+) on the structure and oxygen reduction reaction of BFO used as a cathode for SOFCs. The materials are prepared by solid-state method and their structural, electronic, electrocatalytic properties are characterized and compared. X-ray diffraction reveals 5 mol% A-site or B-site dopant is sufficient to stabilize the cubic phase of BFO, as predicted by the lattice calculation. X-ray photoelectron spectroscopy and iodometric titration demonstrates that neither of the two doping sites has obvious advantage over the other towards the formation of additional oxygen vacancies. B-site doped BFO shows a lower electrical conductivity than A-site doped ones, however, they have much quicker response to electrical conductivity relaxation, likely originating from the expanded lattice size. With the largest oxygen vacancy concentrations, Ba0.95La0.05FeO3-δ and BaFe0.95Zr0.05O3-δ stand out from the A-site and B-site doped BFO, respectively, and polarization resistances of 0.029 Ω cm2 and 0.020 Ω cm2 are achieved at 700 °C, . With a similar amount of oxygen vacancies, B-site doping is more advantageous for enhancing oxygen bulk diffusion kinetics, and thus ORR activity.
(Invited) Electrochemical Synthesis of Multiadducts from [60]Fulleroindolines
Authors: Wang Guan-Wu 
Published: February 2020

[60]Fulleroindolines can accept two electrons to form the corresponding dianions, which involve the heterolytic cleavage of the C60－N bond. The ring-opened structures are perfect building block for the further functionalizations. The synthesis of both tetrafunctionalized and hexafunctionalized products with unusual addition patterns have been achieved.[1]

References
[1]. Xiao, Y.; Zhu, S.-E; Liu, D.-J.; Suzuki, M.; Lu, X.; Wang, G.-W. Angew. Chem. Int. Ed.
2014, 53, 3006-3010.
(Invited) Tailoring Graphene for Spintronics
Authors: Miranda Rodolfo 
Published: February 2020

The development of graphene spintronic devices requires that, in addition to its capability to passively transmit spins over long distances, new magnetic functionalities are incorporated to graphene. By growing epitaxially graphene on single crystal metal surfaces under UHV conditions [1] and either adsorbing molecules on it or intercalating heavy atoms below it, long range magnetic order or giant spin-orbit coupling, respectively, can be added to graphene.
i) Achieving long range magnetic order by a monolayer of electron acceptor molecules adsorbed on graphene /Ru(0001).
Epitaxial graphene is spontaneously nanostructured forming an hexagonal array of 100 pm high nanodomes with a periodicity of 3 nm [2]. Cryogenic Scanning Tunnelling Microscopy (STM) and Spectroscopy and DFT simulations show that TCNQ molecules deposited on gr/Ru(0001) acquire charge from the (doped) substrate and develop a sizeable magnetic moment revealed by a prominent Kondo resonance. The molecular monolayer self-assembled on graphene develops spatially-extended spin-split electronic bands. The predicted spin alignment in the ground state is visualized by spin-polarized STM at 4.6 K [3]. The system shows promising perspectives to become an effective graphene-based spin filter device.
ii) Introducing a giant spin-orbit interaction on graphene/Ir(111) by intercalation of Pb. The intercalation of an ordered array of Pb atoms below graphene results in a series of sharp pseudo-Landau levels in the differential conductance revealed by STS at 4.6 K. The vicinity of Pb enhances by four orders of magnitude the, usually negligible, spin-orbit interaction of graphene. The spatial variation of the spin-orbit coupling creates a pseudo-magnetic field that originates the observed pseudo-Landau levels [4]. This may allow the processing and controlled manipulation of spins in graphene.
References
[1] A.L. Vázquez de Parga et al, Phys. Rev. Lett. 100, 056807 (2008) [2] B. Borca et al, Phys. Rev. Lett. 105, 036804 (2010) [3] M. Garnica et al, Nature Physics 9, 368 (2013) [4] F. Calleja et al, Nature Physics 11, 43 (2015)
Peculiar Magnetic Properties in Doped and Edge Functionalized Silicene Nanoribbons
Authors: Mehdi Aghaei Sadegh , Monshi Md Monirojjaman , Calizo Irene 
Published: February 2020

Motivated by the exceptional properties of graphene, other two-dimensional (2D) nanomaterials beyond graphene such as silicene have emerged with growing interest. Silicene is attractive for its exceptional characteristics and compatibility with silicon based nanoelectronics. It is believed that silicene may challenge graphene due to a longer spin-diffusion time, a longer spin coherence length, and a much larger spin-orbit coupling gap. Half-metallic materials and spin-gapless semiconductors (SGS) are highly desirable for spintronics because they provide 100% spin-polarized currents around their Fermi level. Spin filters and spin field effect transistors (FETs) are one of the potential applications of these types of materials. Silicene nanoribbon (SiNR) as an approach to opening a band gap in a silicene sheet is a promising material for spintronics due to its unique magnetic properties. In this study, a first-principle method based on density functional theory (DFT) is used to investigate the stability, electronic, and magnetic properties of edge hydrogenated and fluorinated SiNRs. Edge functionalization of all possible types of SiNRs such as armchair, zigzag, Klein, reconstructed Klein, pentagon-heptagon, and the combination of the edges are studied. It is found that edge fluorinated structures are much more stable than that of edge hydrogenated. It is also discovered that tri-fluorinated Klein edge SiNR and di-hydrogenated armchair edge SiNR are the most stable structures when the edges are terminated with fluorine and hydrogen atoms, respectively. While, the symmetric edge functionalized zigzag SiNRs show antiferromagnetic semiconductor behaviour. Considering spin-polarization, the asymmetry in edge functionalization bring various and extraordinary magnetic states, such as SGS, ferromagnetic metals or semiconductors, and antiferromagnetic metals. In order to discover the effects of doping on the magnetic and electronic properties of edge functionalized SiNRs, N- or B-doped SiNRs are considered. It is revealed that the dopants energetically prefer to be substituted with Si atoms at the edge of SiNRs. Interestingly, the remarkable SGS and half-metal character, as well as ferromagnetic metallic behavior are observed in N- or B- doped armchair, zigzag, and Klein edge SiNRs which are highly advantageous for spintronics applications. These new findings encourage further experimental investigations in the development of SiNRs based nanoelectronics with spin tuning.
(Invited) Electrostatically Tunable Graphene Metasurfaces for Controlling Mid-IR Radiation
Authors: Brar Victor Watson 
Published: February 2020

Metasurfaces composed of sub-wavelength fabricated structures have shown potential for exceptional control of light. In this talk I will show that by incorporating graphene into the structure of a metasurface, devices can be fabricated that have electrostatically tunable emissivities and reflectivities. It will be shown that the thermal emission from a metasurface can be widely varied in terms of spectral shape, polarization and intensity, and that thermally emitting devices with Mhz response times can be created in this way. By carefully controlling the DC permittivity, index of refraction, and thickness of the supporting substrate, it will also be demonstrated that the efficiency and optical response of these devices can be dramatically altered. Notably, the coupling of graphene plasmons with substrate phonons is found to play an important role in the spectral response of these metasurfaces, and the use of high-k dielectrics can increase maximum efficiency and range of control attainable in graphene metasurfaces.
Cytotoxicity of Graphene Derivatives and Exfoliated Transition-Metal Dichalcogenides (MoS2, WS2, and WSe2)
Authors: Teo Wei Zhe , Chng Elaine Lay Khim , Sofer Zdeněk , Pumera Martin 
Published: February 2020

Many 2D nanomaterials have been demonstrated to possess amazing physiochemical properties and are likely to be incorporated in future consumer products. Therefore, there is a urgent need to ensure that these nanomaterials do not cause adverse health effects. In this study, the cytotoxicity of three common exfoliated TMDs (exTMDs), namely MoS2, WS2, and WSe2, were compared with that of graphene oxides and halogenated graphenes to determine which group of 2D nanomaterials would display better biocompatability. Cell viability assessments using methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8) assays on human lung carcinoma epithelial cells (A549) exposed to varying concentrations of these 2D nanomaterials revealed that MoS2 and WS2 nanosheets induced very low cytotoxicity to A549 cells, even at high concentrations. On the other hand, WSe2 was found to exhibit dose-dependent toxicological effects on A549 cells, reducing cell viability to 31.8 % at the maximum concentration of 400 μg mL−1. In comparison with graphene oxides and halogenated graphenes, MoS2 and WS2 were much less hazardous, whereas WSe2 showed similar degree of cytotoxicity, suggesting that MoS2 and WS2 might be suitable and safe materials for potential applications. However, future in-depth studies should be built upon this first work on the in vitro cytotoxicity of MoS2 and WS2 to ensure that they do not pose acute toxicity. Lastly, nanomaterial-induced interference control experiments indicated that MTT assay is not suitable for measuring the cytotoxicity of exTMDs as inflated absorbance values will be obtained due to undesired reaction between exTMDs and the MTT assay viability markers, giving false impressions that the materials are less toxic.
(Invited) Porphyrin-Capped Au Clusters As Building Blocks for Energy Conversion
Authors: Teranishi Toshiharu 
Published: February 2020

The structure of nanomaterial determines their individual properties and suprastructures they can form [1-3]. Therefore, it is very important to create the size controlled nanostructures with anisotropic binding sites. However, precious control over size of metal clusters and conformation of protective ligands has been a challenging subject. In this study, we report the synthesis of the Au clusters (AuCs) capped by a certain number of porphyrins derivatives in a face coordination fashion [4-7]. The ground state interaction and excited state photochemical behavior of these porphyrirn face-coordinated AuCs will be also presented.
[1] Kanehara, M.; Arakawa, H.; Honda, T.; Saruyama, M.; Teranishi, T. Chem. Eur. J.
2012, 18, 9230.
[2] Eguchi, M.; Mitsui, D.; Wu, H.-L.; Sato, R.; Teranishi, T. Langmuir
2012, 28, 9021.
[3] Chen, L.; Sakamoto, M.; Sato, R.; Teranishi, T. Faraday Discuss.
2015, 181, 355.
[4] Kanehara, M.; Takahashi, H.; Teranishi, T. Angew. Chem. Int. Ed.
2008, 47, 307.
[5] Sakamoto, M.; Tanaka, D.; Tsunoyama, H.; Tsukuda, T.; Minagawa, Y.; Majima, Y.; Teranishi, T. J. Am. Chem. Soc.
2012, 134, 816.
[6] Tanaka, D.; Teranishi, T. et al. Chem. Sci.
2014,5, 2007.
[7] Eguchi, D.; Sakamoto, M.; Teranishi, T., to be submitted.
(Invited) Growth of Ordered ZnO Nanorods Arrays Using Anodic Porous Alumina Templates
Authors: Masuda Hideki , Kondo Toshiaki , Nakazono Takashi , Yanagishita Takashi 
Published: February 2020

The fabrication of ordered semiconductor nanostructures has attracted increasing interest due to its applicability to various functional devices. Among them, the semiconductor nanorods array is one of typical nanostructures available for the functional optical devices including solar cells, and display devices due to its unique physical properties originated from the geometrical structures. Although various fabrication processes for the nanorod arrays have been reported, the efficient fabrication process of the ordered semiconductor nanorods array has not been established so far [1]. In the present report, the formation of the highly ordered semiconductor (ZnO) nanorods array based on anodic porous alumina templates will be presented. The anodic porous alumina, which is formed by anodization of Al in acidic electrolyte, is one of typical self-ordered material with highly ordered hole arrangement [2]. The advantage of this material is its high controllability of the geometrical structures based on the anodizing conditions. Especially, under the appropriate low voltage anodization condition, the highly ordered hole array structures with small hole interval and hole size can be obtained [3]. The hole interval and hole size in this highly ordered porous alumina were typically 25 nm and 10 nm, respectively. In the present work, ZnO nanorods arrays were fabricated through the hydrothermal reaction [4] using the anodic porous alumina as a template for the synthesis. Based on the present process, the highly ordered arrays of ZnO nanorods could be fabricated on the substrates. The geometrical structures of the ZnO nanorods arrays were controlled by changing the structures of the porous alumina templates. The obtained nanostructures will be applied to the fabrication of various kinds of energy conversion devices, which require the highly ordered nanostructures of semiconductors.
1. W. I. Park, D. H. Kim, S.-W. Jung, G.-C. Yi, Appl. Phys. Lett., 80, 4232 (2002).
2. H. Masuda and K. Fukuda, Science, 268, 1466 (1995).
3. H. Masuda, K. Takenaka, T. Ishii, K. Nishio, Jpn. J. Appl. Phys., 45, L1165 (2006).
4. T. Shinagawa, S. Watase, M. Izaki, Cryst. Growth Des., 11, 5533 (2011).
(Invited) Photoinduced Electron Transfer Processes of Trifluorinated Molecules Dispersed in Conjugated Polymer Films and at Interfaces with Swcnts
Authors: Rumbles Garry , Blackburn Jeffrey L. , Ihly Rachelle , Reid Obadiah , Park Jaehong , Strauss Steven H. , Boltalina Olga V. , Coffey David C 
Published: February 2020

The use of a Marcus formulation to describe photo-induced electron transfer processes in the complex blends of conjugated polymers and fullerenes associated with organic photovoltaics is rare. The conventional approach considers the polymer and fullerene to form a type II band offset similar to a picture for two inorganic semiconductors. A motivation for this presentation is to ask whether this simple model is correct and only the energetics need be considered when examining the driving force for the photo-induced electron transfer process. Or whether a re-organization energy is also required to describe the effect and therefore an optimum driving force is required to realize high charge separation yields.
This presentation will describe two studies using a series of trifluoromethylfullerenes (TMFs) dispersed at low concentration in a conjugated polymer film or in a bilayer forming an interface with a layer of chiral-pure single-walled carbon nanotubes (SWCNTs). The fullerene series provides exquisite control over a wide range of reduction potentials of the fullerene, and can thus influence the driving force for photo-induced electron transfer studies. In both experiments, the use of the electrodeless technique of flash photolysis, time-resolved microwave conductivity (fp-TRMC) which provides a sensitive probe of the yield and kinetics of charges generated in both systems.