bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of RGO Coating of Li-Rich Cathode Material on Electrochemical Performance
Authors: Lim Sung Nam , Kim Kiyoung , Song Shin Ae 
Published: February 2020

Li-rich, xLi2MnO3∙(1-x)LiMO2 (M = Ni, Co and Mn), cathode material have attracted interest due to their high capacity (>250 mAh g-1), which is a key characteristic required for a power supply to meet the energy demands of electric vehicles. However, they still were hard to use commercial cathode material, because their poor rate capability and inferior cycle performance caused by low electronic conductivity of active material and phase transformation induced from side reaction. To solve these critical problems, many groups have suggested coating the cathode material with a more stable material such as Al2O3, TiO2, and Li4Ti5O12. However, these coating materials lead to poor rate capability owing to their electronic insulated property, although they enhance cycle performance.
In this study, we prepared RGO costed Li-rich cathode material by using self-assembly to enhance rate capability as well as cycle performance. We investigated the effect of RGO coating on physical properties of cathode material such as structure, morphology and surface property. And we also investigated effect on the electrochemical performance.
Electrochemical Performance of Uspld Prepared Silicon Anode Electrodes
Authors: Valikangas Juho Pekka , Lassi Ulla , Hu Tao 
Published: February 2020

Introduction

Secondary battery materials are in great demand of research and new high energy density materials are required for higher quality of batteries1. Silicon based anode is one of the most promising anode material for Li-ion batteries, because it has high theoretical capacity (4200 mAh/g, lithiated to Li4.4Si) and low operating voltage (~0.3V versus Li/Li+) 2,3 Challenges for silicon based anode are the capacity fading during the first cycle and the poor cycle performance.

Experimental

Si layers on copper foil were produced by Picodeon’s ultra-short pulsed laser deposition (USPLD) technology. This technology utilizes pulsed lasers with pulse lengths in the picosecond range and high pulse repetition rates (MHz). The pulsed laser beam is delivered to the surface of the target, which is placed inside a vacuum chamber, through a scanner and a telecentric lens. With this beam delivery approach a focused scan line can be produced on the target. Material is removed by the laser pulses from the target material, and movement of the substrate through the material cloud generated by this line source enables straightforward deposition of uniform layers even on larger surface areas.
Cells with USPLD prepared Silicon anode and LiNi0.5Co0.2Mn0.3O2 cathode were prepared in the humidity controlled dry room. Cathode thicknesses were controlled to have different specific capacities for the silicon anode material. Different type of electrolytes and testing parameters were used to achieve better electrochemical results for USPLD silicon anodes.

Results and discussion

Results showed that electrochemical testing parameter and materials used in the tests have great influence on the electrochemical performance of silicon anode materials. Especially, additives used in the electrolyte seems to have a great influence on the cycle performance of silicon based anode material. Results also showed that silicon material should not charge full, instead 1500 mAh/g show much better electrochemical properties. Results also clarified some problems with half-cell and full-cell tests.
We have demonstrated that the 10µm thick 100% silicon anode layer prepared by USPLD can replace 50µm graphite layer in the Li-ion cell. Total energy density is higher for silicon-NCM cell than for graphite-NCM cell after hundred cycles. Still challenge is the poor cycle performance compared to graphite anode; however, results showed that it is possible to improve cycling properties by electrolyte additives and limiting charging capacity. Silicon based anode material is a good candidate for the next generation Li-ion battery.

Reference
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:

W Choi and D. Aurbach (2016) Nature rewiew materials 1. (2016) 16013

A Huggins (1999) Journal of Power Sources, Vol 81-82, pp.13-19

Hui Wu, Yi Cui (2012) Nanotoday, Vol 7, issue 5, pp 414-429
Ammonia for Proton Conducting Medium in Metal-Organic Frameowkrs
Authors: Lim Daewoon , Kitagawa Hiroshi 
Published: February 2020

Proton transport is essential and critical in a biological system and electrochemical devices. In particular, the fundamental understanding of proton conduction mechanism in conducting medium is important to design the efficient proton conductor. The overwhelming majority of proton conducting medium is water (H2O) which was intensively investigated because water can form the efficient hydrogen bonding networks by symmetric two proton donor and two acceptor sites resulting in degenerated proton conduction system (H3O++H2O ⇔ H2O+H3O+). In this point of view, we believe that ammonia (NH3) can be a next promising conducting medium due to its similar molecular system to water. Specifically, it shows a small molecular size (2.60 Å), three proton donor sites/ one acceptor site, and degenerated proton conduction system (NH4
++NH3 ⇔ NH3+NH4
+). Considering the fluid phase of NH3, a confined environment should be required to achieve NH3 proton conductor. The porous crystalline metal-organic frameworks (MOFs), tunable solid, are emerging as a new class of solid electrolyte because of a considerable porosity and versatile sorptivity. In particular, the pore of MOFs is a suitable platform to confine the guest molecules. In addition, a simultaneous proton donation from framework to NH3 can induce the conjugated acid-base system in the pores.
Here, we show, for the first time, proton conductivity through the simultaneously confined NH3 in MOFs by NH3 adsorption. We choose highly stable Al-based MOFs consisting of one-dimensional channel and MO4(OH)2 secondary building units (SBUs) interconnected by dicarboxylate groups. Fuethermore, we can tune the pore environment by using the different fuctionla groups of ligand. We found cooperative ammonia adsorption with simultaneous ammonium formation and the highly enhanced proton conductivity as NH3 pressure increases. Tthe structure analysis of MOFs incorporating NH3 by Rietveld refinement and dynamic motion study of confined NH3 by 2H solide-state NMR help to understand proton conduction mechanism. These results clearly support the Grotthuss mechanism not seen in bulk NH3 system. We believe that this research may provide a design strategy for material using NH3 as a conducting media as well as an energy carrier.
Metal-Organic Frameworks and Carbon Nanotubes – Imparting Electrical Conductivity to MOF Composites
Authors: Schulze Hendrik A. , Brechtken Benedikt , Schaate Andreas , Haug Rolf J. , Behrens Peter 
Published: February 2020

Metal-organic frameworks (MOFs) and carbon nanotubes (CNTs) have emerged as two of the most promising material classes in the last few years. Both material classes have been thoroughly investigated regarding their structures, production methods, as well as physical and chemical properties. However, despite the versatility of MOFs, nearly all members are electrically insulating. Hence, these materials have not been the first choice in the field of electronic devices. On the contrary, CNTs show high electrical and thermal conductivities, combined with low densities and high mechanical robustness. Up to now, only a few MOF–CNT-composites have been described with the focus on hydrogen storage, the use in supercapacitors or as humidity sensors.[1-3]

In this work, we describe MOF–CNT-composites that combine the electrical conductivity of CNTs with the high porosity of MOFs and, furthermore, coagulate the CNTs to minimize unfavourable health effects. We present the results of the crystallization of the MOFs on CNTs by using the stable Zr-based MOFs of the UiO-66 group[4] with different linker molecules to create different chemical properties and electronic effects. The MOF particles sizes and morphologies are controlled be using modulated syntheses.[5]

The composites can be provided in different forms. On the one hand, strongly intergrown composites of MOF particles that have crystallized around carbon nanotubes, application as electrode materials in batteries or in thermoelectric can be envisaged. On the other hand, thin films of the composites can be anchored on different substrates. Furthermore, we also can create nanoobjects consisting of individual CNT bearing MOF nanoparticles (Fig. 1).

References:

[1] S.J. Yang, J.Y. Choi, H.K. Chae, J.H. Cho, K.S. Nahm, C.R. Park, Chem. Mater.
2009, 21, 1893–1897.
[2] P. Wen, P. Gong, J. Sun, J. Wang, S. Yang, J. Mater. Chem. A
2015, 3, 13874–13883.
[3] K.N. Chappanda, O. Shekhah, O. Yassine, S.P. Patole, M. Eddaoudi, K.N. Salama, Sensors and Actuators B
2018, 257, 609–619.
[4] J.H. Cavka, S. Jakobsen, U. Olsbye, N. Guillou, C. Lamberti, S. Bordiga, K.P. Lillerud, J. Am.
Chem. Soc.
2008, 130, 13850–13851.
[5] A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebcke, P. Behrens, Chem. Eur. J.
2011, 17, 6643–6651.

Figure 1
Superconductive (Cu)TTF@TCNQ Nanosheets Detected By Peakforce Tunneling Atomic Force Microscopy
Authors: Chen Dong-Hui , Fu Zhihua , Redel Engelbert 
Published: February 2020

Superconductive (Cu)TTF@TCNQ Nanosheets have been deposited in various thicknesses and characterized through peakforce tunneling AFM.
TTF (Tetrathiofulvalene) and TCNQ (tetracyanochinodimethan) are conjugated organic molecules. However, they formed a “metallic conductive interface”, by a charge transfer (CT) complex. Whereby TCNQ is an acceptor molecule and TTF is a donor molecule. [1] Such charge transfer (CT) complexes possess an increased charge carrier concentration within the TTF@TCNQ nanosheets producing hole and electron carriers, donors and anions with holes, or cations and acceptors with electrons. Therefore, superconductivity have been reported for this system. [
2,3
]

Cu:TTF and Cu:TCNQ nanosheets have been deposited by in different thicknesses by various methods, e.g. spin-coating, dip-coating or electrodeposition methods. The thicknesses have been performed in the range of 2 nm to 30 nm. Peakforce tunneling AFM measurements can be performed on this systems. This TUNA characterizes ultra-low currents (<1pA) through the thickness of nanosheets, and is of particular importance when electrical characterization of conductivity samples is needed at high lateral resolution. High-resolution current mappings of these nanosheets were enabled as well as the corresponding morphology images. Moreover, The I-V currents in the range from pA to nA of these nanosheets have been detected due to the high sensitivity and accuracy of the Peakforce TUNA mode. The resistances of the (Cu)TTF@TCNQ nanosheets can be calculated by using this currents and then the conductivities were also been obtained accordingly.
These superconductive nanosheets will help to construct novel porous superconductive SURMOF hybrid materials in the near future for various device applications.

R
eference

Tang, Q.; Zhou, Z.; Chen, Z. J. Phys.
Chem. C, 2011, 115, 18531–18537.

Kirtley J. R.; Mannhart, J. Nat.
Mater., 2008, 7, 520-521.

Alves, H.; Molinari, A. S.; Xie, H.; Morpurgo, A. F. Nat. Mater., 2008, 7, 574-580

Figure 1
Resistive Switching Phenomena of Metal-Organic Framework Nanosheets Detected By Peakforce Tunneling Atomic Force Microscopy
Authors: Xiu Jingwei , Fu Zhihua 
Published: February 2020

Graphene[1], an atom-thin sheet of carbon discovered in 2004, has created a brand new era in two-dimensional (2D) materials owing to its immense potential in both basic and applied research. In recent years, numerous new 2D nanomaterials possessing atomically thin structures have been investigated.[2] Metal-organic Framework (MOF) nanosheets, as a new category of 2D materials, exhibit diverse structural and physicochemical properties as a result of the self-assembly of metal ions or clusters and polydentate bridging ligands.[3] Arising from their unique structural features combining MOF and 2D nano-structures, MOF nanosheets exhibit unprecedented physical, electronic, chemical, and optical properties and offer implementation in application field.
Resistive random-access memory is a predominant candidate for future non-volatile memories. It relies on the formation/annihilation of highly conductive paths, leading to the creation of two stable and reversible resistive states.[4] To achieve the desirable memory characteristics, new materials and a better understanding of the physics triggering the resistive switching (RS) in this system are required. MOF nanosheets with ultrathin nanostructures, high-density active sites and rapid ion/electron transport can offer best opportunities for fundamental and technological research in the RS applications. However, the progress in fundamental understanding has been hampered by the extremely small sizes (of the region) involved in the RS transition region presenting a severe challenge for its physical characterization using conventional metrology methods.
PeakForce tunneling (PFTUNA) atomic force microscopy[5] provides direct, precise force which makes it shows high spatial resolution and routine high current sensitivity. Therefore, the MOF nanosheets combined with PFTUNA technology can present the best tradeoff between existing process technology and RS performances. In this work, we intend to synthesize Ag-S nanosheets with distorted hexagonal topology (Figure 1a-b). By mean of PFTUNA technology of AFM, MOF nanosheet based memory device is constructed and characterized (Figure 1c). A conductive probe to apply a voltage to the top electrode of the single device thereby setting the memory device into its state ON, i.e., its low-resistive state (LRS), or OFF state, i.e., its high-resistive state (HRS) (Figure 1d).

Figure 1
Local Static and Dynamic Field Fluctuations Near the Cu-Ion in HKUST-1 from 63cu-NMR
Authors: Bernal Oscar O , O'Dea Greta , Mohammed Zeinab H. , Redel Engelbert , Baumgart Helmut 
Published: February 2020

We report on the local field fluctuations, both of static and dynamic character, at the position of the Cu ions in the Cu(II)-based porous metal-organic framework (MOF) HKUST-1 Cu2(BTC)3 powder. We will compare measurements done in the HKUST-1 pristine form of the material and HKUST-1 infiltrated with tetracyano-quinodimethane (TCNQ). NMR Spectroscopy is a sensitive local probe which can sample both magnetic and charge degrees of freedom of spin bearing nuclei, whose behavior is strongly affected by the magnetic and/or electric activity of neighboring atoms and electrons. Therefore, the loading of TCNQ into the open porous framework of HKUST-1 MOF should have a significant influence in the 63Cu-NMR linewidth.
We present data from 63Cu-NMR linewidth, frequency-shift and spin-lattice relaxation experiments in pristine HKUST-1, which display unusual temperature dependence: the linewidth indicating on the one hand a potential interaction between the 63Cu nuclei and the unpaired electrons in the paramagnetic system of Cu(II), and on the other hand, the frequency-shift together with the spin-lattice relaxation time indicating the existence of a substantial density of electron states at the 63Cu sites, with concomitant changes due to temperature variations. We will discuss these data and those obtained from similar experiments in HKUST-1 when infiltrated with TCNQ.
Work supported by the National Science Foundation under a Partnership for Research and Education in Materials PREM, grant DMR-1523588.
(Invited) Device Fabrication – Positioning and Alignment of MOF Crystals
Authors: Falcaro Paolo 
Published: February 2020

Metal organic frameworks (MOFs) are a class of ultra-porous materials with exceptionally high accessible surface area and structure modularity due to the framework made of inorganic nodes coordinated by organic bridging ligands.[
1
2
,
3
]

A number of increasing studies investigate Metal-Organic Frameworks (MOFs) for a variety of functional applications including sensing, microelectronics, energy production, drug delivery and microfluidics.[
4
] However, MOF-based device fabrication requires synthetic protocols for the controlled growth of the ultra-porous crystals and their integration in suitable platforms.[
4
] This presentation will summarize the recent progress on MOF crystal engineering aspects from positioning technologies to alignment strategies. [
5
,
6
,
7
,8, 9,10,11,12] A particular focus of the presentation will be the current role of ceramics for MOF device fabrication.

References

[1] Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M. Science
2013, 341 (6149), 1230444.
[2] Guillerm, V.; Kim, D.; Eubank, J. F.; Luebke, R.; Liu, X.; Adil, K.; Lah, M. S.; Eddaoudi, M. Chem. Soc. Rev.
2014, 43 (16), 6141.
[3] Kitagawa, S.; Kitaura, R.; Noro, S. Angew. Chem. Int. Ed.
2004, 43 (18), 2334.
[4] Falcaro, P.; Ricco, R.; Doherty, C. M.; Liang, K.; Hill, A. J.; Styles, M. J. Chem. Soc. Rev.
2014, 43 (16), 5513.
[5] Doherty, C. M.; Buso, D.; Hill, A. J.; Furukawa, S.; Kitagawa, S.; Falcaro, P. Acc. Chem. Res.
2014, 47 (2), 396.
[6] Zanchetta, E.; Malfatti, L.; Ricco, R.; Styles, M. J.; Lisi, F.; Coghlan, C. J.; Doonan, C. J.; Hill, A. J.; Brusatin, G.; Falcaro, P. Chem. Mater.
2015, 27 (3), 690.
[7] Ricco, R.; Malfatti, L.; Takahashi, M.; Hill, A. J.; Falcaro, P. J. Mater. Chem. A
2013, 1 (42), 13033–13045.
[8] Liang, K.; Ricco, R.; Styles, M. J.; Bell, S.; Kirby, N.; Mudie, S; Haylock, D.; Hill, A. J.; Doonan, J.; Falcaro, P. Nat.Commun
2015, 6, 7240.
[9] Liang, K.; Ricco, R.; Doherty, C.M.; Styles, M. J.; Hill, A. J.; Takahashi, M.; Falcaro, P. Adv. Funct. Mater.
2014, 24 (14), 1969.
[10] Toyao, T.; Liang, K.; Okada, K.; Ricco, R.; Styles, M. J.; Tokudome, Y.; Horiuchi, Y.; Hill, A. J.; Takahashi, M.; Matsuoka, M.; Falcaro, P. Inorg Chem Front
2015, 2, 434.
[11] Liang, K.; Carbonell, C.; Styles, M.J.; Ricco, R.; Styles, M. J.; Jiwi, C.; Richardson, J.J.; Maspoch, D.; Caruso, F.; Falcaro, P. Advanced Materials
2015, 28 (36), 7910
[12] Falcaro, P.; Okada, K; Hara, T.; Ikigaki, K.; Tokudome, Y.; Thornton W. A.; Hill A. J.; Williams T.; Doonan, C.; Takahashi, M. Nature Materials
2017, 16(3), 342.

Figure 1
(Invited) Optoelectronic Processes in Covalent Organic Frameworks
Authors: Bein Thomas 
Published: February 2020

New opportunities emerge by spatially integrating photoactive molecular building blocks into the crystalline lattice of covalent organic frameworks (COFs), thus creating models for organic bulk heterojunctions and porous electrodes for photoelectrochemical systems. In this presentation, we will address means of controlling the morphology and packing order of COFs in thin films (1) and with spatially locked-in building blocks.(2) Regarding the latter, the design of well-defined periodic docking sites enables us to achieve remarkably high crystallinity with several multidentate building blocks and a series of linear bridging units.
We will discuss different strategies aimed at creating electroactive networks capable of light-induced charge transfer. For example, we have developed a COF containing stacked thienothiophene-based building blocks acting as electron donors with a 3 nm open pore system, which showed light-induced charge transfer to an intercalated fullerene acceptor phase.(3) Contrasting this approach, we have designed a COF integrated heterojunction consisting of alternating columns of stacked donor and acceptor molecules, promoting the photo-induced generation of mobile charge carriers inside the COF network.(4) Moreover, additional synthetic efforts have led to several COFs integrating extended chromophores capable of efficient harvesting of visible light, for example (5). Extending newly developed thin film growth methodology to a solvent-stable oriented 2D COF photoabsorber structure, we have recently established the capability of COF films to serve in photoelectrochemical water splitting systems.(6) The great structural diversity and morphological precision that can be achieved with COFs make these materials excellent model systems for organic optoelectronic systems.
(1) D. D. Medina, J. M. Rotter, Y. H. Hu, M. Dogru, V. Werner, F. Auras, J. T. Markiewicz,
P. Knochel, T. Bein, J. Am. Chem. Soc.
2015, 137, 1016.
(2) L. Ascherl, T. Sick, J. T. Margraf, S. H. Lapidus, M. Calik, C. Hettstedt, K. Karaghiosoff, M. Döblinger, T. Clark, K. W. Chapman, F. Auras, T. Bein, Nature Chem. 2016, 8, 310.
(3) M. Dogru, M. Handloser, F. Auras, T. Kunz, D. Medina, A. Hartschuh, P. Knochel,
T. Bein, Angew. Chem. Int. Ed. 2013, 52, 2920.
(4) M. Calik, F. Auras, L. M. Salonen, K. Bader, I. Grill, M. Handloser, D. D. Medina,
M. Dogru, F. Lobermann, D. Trauner, A. Hartschuh, T. Bein, J. Am. Chem. Soc.
2014, 136, 17802.
(5) N. Keller, D. Bessinger, S. Reuter, M. Calik, L. Ascherl, F. C. Hanusch, F. Auras, T. Bein, J. Am. Chem. Soc.
2017, 139, 8194.
(6) T. Sick, A. G. Hufnagel, J. Kampmann, I. Kondofersky, M. Calik, J. M. Rotter, A. Evans, M. Döblinger, S. Herbert, K. Peters, D. Böhm, P. Knochel, D. D. Medina, D. Fattakhova-Rohlfing, T. Bein, J. Am. Chem. Soc.
2018, 140, 2085.
(Invited) Moving Electrons and Holes through Porous MOFs and MOF-Supported Catalysts
Authors: Goswami Subhadip , Kung Chung-Wei , Palmer Rebecca , Farha Omar K. , Hupp Joseph T. 
Published: February 2020

Porous, thin-film, water stable metal-organic frameworks (MOFs) are potentially highly attractive as electrocatalysts as they can present reactant-accessible catalysts at high areal concentration on electrode surfaces. Indeed, such films, if constructed from molecular catalysts, can present the equivalent of several hundred monolayers or more of catalyst -- amounts that can translate into decreases of hundreds of millivolts in kinetic overpotential relative to overpotentials for otherwise equivalent solution-phase electrocatalysts present at millimolar concentrations. Similar conclusions can be reached for catalysts consisting of MOF-node-supported, metal-oxygen or metal-chalcogen clusters. Required for efficacious electrocatalysis, however, is reasonable electrical conductivity, where the basis for conductivity may be site-to-site redox hopping or may instead operationally resemble band-like electronic conductivity. For electrode-supported MOF films having thicknesses of around a micron, site-to-site charge hopping rates on the order of 105 sec-1 should be sufficient to sustain catalytic currents of tens of mA/cm2. Alternatively, MOF electronic conductivities on the order of 10-2 Siemens/cm (roughly seven and a half orders of magnitude less than the conductivity of copper) should be sufficient to sustain catalytic currents of tens of mA/cm2 with only marginal iR penalties. Thus, in comparison to many applications, the degree of conductivity required for MOF thin-film mediated electrocatalysis is modest.
This presentation will describe some approaches to rendering highly-porous MOF films sufficiently electrically conductive to support electrocatalysis. Included will be examples of highly anisotropic electrical conductivity, underscoring the role that MOF topology can play in defining both hopping-like and band-like conductivity. Also included may be examples of intentional chemical modulation of MOF conductivity. Based on these and other examples, some potentially transferrable principles for designing electrocatalysis-competent, conductive MOFs will be proffered.