bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Higher Fullerenes to Channel Halogen-Halogen Interactions
Authors: Ghiassi Kamran , Wescott Joseph , Chen Susanne Y. , Stevenson Steven , Balch Alan L. , Olmstead Marilyn M.
Published: February 2020

Fullerenes are fascinating to study in the solid state in regard to their supramolecular and host-guest chemistry. Through the utilization of single-crystal X-ray diffraction, the molecular and supramolecular structures of fullerenes can be determined. Much focus has been given to the host-guest nature of fullerenes in which the complementary molecules are often quite large and resemble the shape of the cage. Little focus, however, has been given to flat, smaller co-crystallization molecules. The molecules 1,2,4,5-tetrabromobenzene and hexabromobenzene were successfully co-crystallized with C60, C70 and Sc3N@Ih
(7)-C80 in order to study π-π interactions. While the C60 structures show typical van der Waals interactions, the higher fullerenes show additional, unique halogen-halogen interactions.

Figure 1
Unveiling the Nature of Supramolecular Crown Ether-C60 Interactions
Authors: Moreira Luis , Calbo Joaquín , Krick Calderon Rafael M. , Santos José , Illescas Beatriz M. , Aragó Juan , Nierengarten Jean-François , Guldi Dirk M. , Ortí Enrique , Martin Nazario
Published: February 2020

Construction of artificial photoactive devices capable of mimicking photosynthesis by transforming light into chemical potential is one of the most sought objectives in the quest for new sources of energy.[1] For this, chemists have developed a wide variety of covalent and supramolecular structures based on donor-acceptor systems where photon energy is used to produce a photoinduced electron-transfer from the donor to the acceptor moiety.[2]

As a result, in 2010 our group developed a supramolecular exTTF-B18C6 ether receptor for fullerenes which showed an extraordinary affinity (K
a 5.01 × 106 M-1) towards [60]fullerene.[3]This was an outstanding result as previous attempts to complex fullerenes by only one unit of exTTF were unsuccessful. Thus, the presence of crown ethers as recognition patterns seemed to be of paramount importance.

In this work, we have further studied this unexpected result and exploited the potentiality of crown ethers as recognition motifs for fullerenes. Therefore, a series of exTTF-(crown ether)2 receptors, designed to host C60, has been prepared. The size of the crown ether and the nature of the heteroatoms have been systematically changed to fine tune the association constants. Electrochemical measurements and transient absorption spectroscopy assisted in corroborating a charge transfer in the ground state and in the excited state leading to the formation of radical ion pairs featuring lifetimes in the range from 12 to 21 ps. To rationalize the nature of the exTTF-(crown ether)2•C60 stabilizing interactions, theoretical calculations have been carried out, prompting to a synergetic interplay of donor-acceptor, π-π, n-π and CH···π interactions, which is the basis for the affinity of our novel receptors towards C60.

References:

[1] J. L. Delgado, P.-A. Bouit, S. Filippone, M. A. Herranz, N. Martín, Chem. Commun. 2010, 46, 4853-4865.

[2] H. Dong, H. Zhu, Q. Meng, X. Gong, W. Hu, Chem. Soc. Rev.
2012, 41, 1754-1808.

[3] B. Grimm, J. Santos, B. M. Illescas, A. Muñoz, D. M. Guldi, N. Martín, J. Am. Chem. Soc.
2010, 132, 17387-17389.

Figure 1
Carboxylate Fullerene Derivatives in Redox-Reversible Bimetallic Assemblies
Authors: Suarez Catalina , Rivera-Nazario Danisha Marie , Echegoyen Luis
Published: February 2020

Supramolecular assemblies containing bimetallic units displaying paddlewheel motifs are well known, especially Zn2 and Cu2.  However, assemblies containing stable, electrochemically active and reversible bimetallic units are scarce, and their physicochemical properties are not well studied. These bimetallic units (e.g. Cr2, Mo2, Ru2 and W2) possess very rich electrochemical properties and exhibit multiple bonding between the metal atoms. Fullerenes containing carboxylic acid addends are excellent candidates to complement the bimetallic units due to their rich and stable redox properties. We successfully synthesized and characterized three different carboxylate fullerene derivatives. After we preassembled a Secondary Building Unit (SBU) using labile bridging ligands such as formamidinates, carboxylates  and acetonitriles, we prepared a series of new discrete molecular systems containing the synthesized fullerene derivatives (See image below) and studied their electrochemical properties. Of particular interest is the degree of electronic coupling between the fullerenes and through the metallic centers via the carboxylate connections. In the future, discrete bimetallic assemblies will  be extended to form Metal Organic Frameworks (MOFs).

Figure 1
Preparation and Photophysical Properties of Molecular Architectures Composed of Polycyclic Aromatic Hydrocarbon and Porphyrin Derivatives
Authors: Hasobe Taku
Published: February 2020

The self-assembly of organic molecules to form ordered nanoarchitectures is currently receiving great interest as a means of constructing well-defined nanostructures. The possibility for controlling macroscopic structures through a proper choice of the molecular components paves a way to design and synthesize materials with specific properties and functions. One of the main challenges is the consturction of highly organized supramolecular multicomponent nanostructures in a well-controlled manner, which is very related to the molecular systems of natural photosynthesis highly organized in quaternary protein structures. Therefore, utilization of electron donor (D) and acceptor (A) molecules such as polycyclic aromatic hydrocarbon derivatives (PAHs) (e.g., perylene and coronene) for controlled assembly has stimulated the related research fields such as molecular electronics and light energy conversion.1-3

Disc-like PAH derivatives such as triphenylene functionalized with alkyl chains, which self-assemble into supramolecular structures due to the stacking π−πinteractions, may be a good candidate to construct face-to-face complexes with planar dye molecules. In this context, 1,4,5,8,9,12-hexaazatriphenylene (HAT) derivatives are good electron acceptors since these molecules have the electron deficient pyrazine units.

Along this point, planar porphyrins and 1,4,5,8,9,12-hexaazatriphenylene (HAT) derivatives are expected to form supramolecular charge-transfer (CT) π-complexes, exhibiting broad CT absorption bands. The redox properties of porphyrins and HAT derivatives measured by electrochemical measurements indicate that porphyrins and HAT derivatives act as electron donors and acceptors, respectively. The 1 : 1 CT complexes between porphyrins and HAT derivatives was successfully examined by the UV-vis, fluorescence and 1H NMR measurements. The occurrence of ultrafast photoinduced electron transfer from the porphyrin unit to the HAT unit was confirmed by transient absorption measurements. Finally, highly one-dimensional assembly composed of porphyrin and an HAT derivatives was observed by transmission electron microscope (TEM) and atomic force microscope (AFM).

Additionally, the related molecular architectures containing fullerene derivatives will be also discussed in this presentation.

References

(1)  Hirayama, S.; Sakai, H.; Araki, Y.; Tanaka, M.; Imakawa, M.; Wada, T.; Takenobu, T.; Hasobe, T. Chem. Eur. J.
2014, 20, 9081.

(2)  Ida, K.; Sakai, H.; Ohkubo, K.; Araki, Y.; Wada, T.; Sakanoue, T.; Takenobu, T.; Fukuzumi, S.; Hasobe, T. J. Phys. Chem. C
2014, 118, 7710.

(3)  Sakai, H.; Shinto, S.; Araki, Y.; Wada, T.; Sakanoue, T.; Takenobu, T.; Hasobe, T. Chem. Eur. J.
2014,
20, 10099.
Photo-Physical Properties and Applications of Multi-Porphyrinic Polypeptides
Authors: Solladie Nathalie
Published: February 2020

In honor of Prof. Fukuzumi.

One of our research field concerns porphyrin-functionalized α-polypeptides to control the spatial organization of the chromophores and enable exciton migration through the pool of porphyrins to mimic the light harvesting antennae of the photosynthetic system.1

      In the photosynthetic system, the solar energy is collected by pigment molecules attached to the light harvesting complexes, in which the chlorophylls are held in a parallel orientation by fairly short α-helical polypeptides. When a photon hits one of the chlorophylls, the absorbed energy spreads extremely rapidly to the others until the reaction center is reached.1 Succeeding in organizing the porphyrins in a similar way as nature does should provide information about the relation existing between the orientation of the chlorophylls and the efficiency of nature in transferring an excited state over a very long distance and with minimal loss of energy.

      The right-handed 310helical conformation adopted by our poly-L-lysine functionalized with eight porphyrins induces an overlap of the chromophores (studies realized in collaboration with Prof. T. Keiderling, University of Chicago, US), which thus present sufficient electronic coupling to promote a good exciton migration within the molecular wire.

      The properties of our peptides with pendant porphyrins were studied extensively in collaboration with with Professor S. Fukuzumi (Univeristy of Osaka, Japan) and applications were found as organic photovoltaic cells,2 multiple photosynthetic reaction centers3 and for the successful purification of Single-Walled Carbon Nanotubes.4

Acknowledgements

This work was supported by the CNRS and the French Ministry of Research. 

References

W. Kühlbrandt, Nature
1995, 374, 497-498.

T. Hasobe, K. Saito, P. V. Kamat, V. Troiani, H. Qiu, N. Solladié, K. S. Kim, J. K. Park, D. Kim, F. D'Souza, S. Fukuzumi, J. Mater.
Chem.
2007, 39, 4160-4170.

S. Fukuzumi, K. Saito, K. Ohkubo, V. Troiani, H. Qiu, S. Gadde, F. D’Souza and N. Solladié, Phys.
Chem. Chem. Phys.
2011, 13, 17019-17022.

 Kenji Saito, Vincent Troiani, Hongjin Qiu, Nathalie Solladié, Takao Sakata, Hirotaro Mori, Mitsuo Ohama,  Shunichi Fukuzumi, J. Phys. Chem. C  2007, 111, 1194-1199.

Figure 1
Fullerenes and Caps By Sequential HF Elimination from F-PAHs
Authors: Böttcher Artur , Weippert Jürgen , Ulas Seyithan , Weis Patrick , Greisch Jean-Francois , Amsharov Konstantin , Kappes Manfred
Published: February 2020

Appropriately functionalized planar fluorinated polycyclic aromatic hydrocarbons (FPAHs) can be efficiently converted into curved carbon structures via a sequence of thermally activated, regioselective HF elimination steps. [1] On surfaces, such HF elimination is associated with a “planar-to-cap transition” which has been studied by scanning probe methods. [2] The resulting caps have recently been applied to the controlled growth of chirality-selected SWCNTs. [3]  We have studied the mechanism of planar-to-curved conversion  in a variety of active model FPAHs (C26H14F2, C36H15F3 and C60H21F9) using both laser induced desorption (LID) as well electron-impact ionization/heating/fragmentation (EIIHF). For all precursors, we observe sequential HF elimination to be the dominant fragmentation channel. Experiments performed on deposited products of the fragmentation cascade (e.g. C26H12), suggest that the pentagon-hexagon structure of the original FPAH carbon network rearranges during fragmentation. The energy flux deposited into the FPAHs is larger in LID than for EIIHF.  As a result, the sequence of regioselective HF elimination steps can to be taken to completion - to form closed fullerene cages and/or fluorine-free carbon caps depending on the precursor FPAH. By combining LID with ion mobility measurements supported by DFT calculations, we have been able to determine the molecular structure of the (intermediate) fragments along the reaction path thus obtaining insight into the fragmentation mechanism.

[1] M. Kabdulov, et al. Chemistry - A European Journal 19 (2013) 17262

[2] K. Amsharov, et al. Angew. Chem. Int. Ed. 49 (2010) 9392

[3] J.R. Sanchez-Valencia, et al. Nature 61 (2014) 512
(Invited) Synthesis, Properties and Applications of Group IV Graphane Analogues
Authors: Jiang Shishi , Arguilla Maxx , Cultrara Nicholas , Goldberger Joshua E.
Published: February 2020

In this talk, we will summarize our recent work on the synthesis, properties, and applications of a new family of two-dimensional materials based on sp3-hybridized Group IV elements. Ligand-terminated Si, Ge, and Sn graphane analogues are an emerging and unique class of two-dimensional materials that offer the potential to tailor the structure, stability, and properties via covalent chemistry. The presence of a fourth bond on the surface of the layers allows these materials to have the surface terminating ligand to be exchanged with a variety of organic functional groups.  These materials feature a direct band gap which can be tuned with the surface ligand and the main group element.  These materials can be synthesized as robust single crystals in gram-scale quantities, exfoliated into single layers, and prepared on conventional VLSI substrates as few-layer thin films.  Furthermore, these graphane analogues are resilient towards oxidation and thermal degradation.  Additionally, we will describe our recent studies on the electronic and thermal properties of these systems. Overall, this class of two-dimensional materials are not only promising building blocks for a variety of conventional semiconductor applications, but also provides a pioneering platform to systematically and rationally control material properties using covalent chemistry.
Group IV Graphane Analogues As Electronic Materials
Authors: Cultrara Nicholas , Goldberger Joshua E.
Published: February 2020

Here, we will describe our recent development of the electronic properties, a new family of two-dimensional (2D) materials based on honeycomb, sp3-hybridized Group IV elements. These ligand-terminated Si, Ge, and Sn “graphane analogues” are an intriguing class of 2D materials that offer the potential to tailor the structure, stability, and properties via covalent chemistry.  The electronic structure of these materials can be systematically controlled by attaching different surface terminating ligands, and even bestowing properties that don’t exist in the normal three-dimensional structure.  For example, with the appropriate surface functionalizing ligand, these 2D materials feature direct band gaps, enhancing silicon and germanium’s performance in photovoltaics, photodetectors, light-emitting diodes, and lasers.    These materials can be synthesized in gram-scale quantities, exfoliated as single-layers, and prepared as thin layers directly on Si and Ge wafers.   Additionally, we will describe our recent studies on controlling the electronic behavior by doping the lattice with Group III and Group V elements.  This class of two-dimensional materials are not only promising building blocks for a variety of conventional semiconductor applications, but also provides a pioneering platform to systematically and rationally control material properties using covalent chemistry.
Evaluating the Electrocatalytic Stability of N-Doped Graphene Nanosheets Used As a Counter Electrode for [Co(bpy)3]3+/2+ Based Porphyrin-Sensitized Solar Cells
Authors: Zhai Peng
Published: February 2020

A significant improvement in efficiency is achieved for porphyrin (YD2-o-C8) based dye sensitized solar cells, coupled with [Co(bpy)3]3+/2+ mediator electrolyte.However, the poison of

the counter electrode (CE) by the [Co(bpy)3]3+/2+ mediator remains a significant barrier to producing a reliable high-performance device. In this paper, nitrogen-doped graphene 

nanosheets (NG) are produced using a low cost solution-based process and used as the CE for [Co(bpy)3]3+/2+ based porphyrin-sensitized solar cell. These produce significantly 

better electrocatalytic activity than the commonly used Pt CE. The superior performance is a result of the increased number of catalytic sites and the wettable surface that is caused

by the substitution of pyridinic and pyrrolic N into the carbon conjugated lattice. To the authors’ best knowledge, the significantly improved cycling stability (>1000 times) of NG CE 

for [Co(bpy)3]3+/2+ redox complexes is demonstrated for the first time.
Modulation of the Electrostatic and Quantum Capacitance of Few Layered Graphene through Plasma Processing
Authors: Narayanan Rajaram , Yamada Hidenori , Karakaya Mehmet , Podila Ramakrishna , Rao Apparao M , Bandaru Prabhakar R
Published: February 2020

A comprehensive understanding of the characteristics of graphene1, with regard to its unique electrical2, optical, and structural attributes would be incomplete unless the inevitable presence of defects have been considered. While such imperfections may limit3 the realization of theoretically predicted attributes, they may also be vital for uncovering new fundamental phenomena and their related applications. Here, we show that the charged defect generation, through argon ion based plasma processing, in few layer graphene (FLG) could be integral to the substantial enhancement of the electrical capacitance, and of potential use4 in electrochemical (EC) energy storage5. By combining EC characterization techniques with detailed Raman spectroscopic analysis, we elucidate the contributions of plasma-induced defects to electrostatic and quantum capacitance.

References:

1. Kastnelson, M. I. Graphene: Carbon in Two Dimensions. (Cambridge University press, 2012).

2. Das Sharma, S., Adam, S., Hwang, E. H. & Rossi, E. Electronic transport in two-dimensional graphene. Rev. Mod. Phys.
83,407 (2011).

3. Banhart, F., Kotakoski, J. & Krasheninnikov, A. V. Structural Defects in Graphene. ACS Nano
5,26–41 (2011).

4. Stoller, M. D., Park, S., Zhu, Y., An, J. & Ruoff, R. S. Graphene-based ultracapacitors. Nano Lett.
8,3498–502 (2008).

5. Simon, P. & Gogotsi, Y. Materials for electrochemical capacitors. Nat. Mater.
7, 845–854 (2008).

Figure 1
Fabrication and Properties of Graphene/Polymer Transparent Conductive Composite Film
Authors: Pang Beili , Yu Liyan , Dong Hongzhou , Dong Lifeng
Published: February 2020

Graphene shows many exceptional properties, such as electrical, thermal, optical, and mechanical properties. When it was used as nanofiller in the preparation of polymer nanocomposites, the properties of the polymer matrix could not be fully exhibited due to easy agglomeration of graphene and bad compatibility between polymer matrix and graphene.[1,2] Polyurethane (PU) is a material characterized by excellent flexibility, high resilience, and durability. PU has been applied in a wide range of industrial applications including coatings, adhesives, foams, and elastomers.

In our study, the surfactant was first introduced to improve the dispersion of graphene in distilled water. The PU copolymer was synthesized with 2, 4-toluene diisocyanate, polyethylene glycol (PEG400) and    2-hydroxyethyl methacrylate. The triethylamine and ethylene diamine reacted with the copolymer as the neutralizing agent and chain extander, respectively. The graphene/PU polymer composite film was cast on glass substrate and cured under UV irradiation. Dispersion of graphene in the polymer matrix strongly depended on the type of surfactant agent, which was confirmed by scanning electron microscopy measurements and thermogravimetric analysis. Decomposition temperatures and residues of the samples increased with the increasing of graphene content. The conductivity of the films was evidently improved due to the introduction of graphene, which was investigated by using a four probe tester. The composite films were bright and transparent. The graphene/PU polymer composite film showed satisfactory conductivity, transparency and thermal resistance properties because the graphene was well dispersed in the polymer matrix. These polymer composite thin films are good candidates that can be applied in various electronic devices such as counter electrode in solar cells, anode materials in rechargeable batteries and light emitting diodes, and so on.

Reference:

[1] H. B. Zhang, W. G. Zheng, Q. Yan, Z. G. Jiang, Z. Z. Yu, Carbon, 50, 5117 (2012).

[2] J. H. Du, H. M. Cheng, Macromol. Chem. Phys. 213, 1060 (2012).
Formulation and Micro-Extrusion of High Graphene or Activated Carbon Loaded Slurries
Authors: Li Ling , Imran Shaik Mohamed , Shaw Leon
Published: February 2020

Our study is focusing on how the dispersion of solid ingredients in solvent affects the micro-extrusion performance. The slurries comprising high loading of graphene (GN) and carbon black (CB)  in solvent N-methyl-2-pyrrolidone (NMP) or DI water with SDS are prepared. In addition the capability of the extrudate to maintain its shape right after extrusion of the slurries will influence the micro-extrusion performance. Six key parameters will be studied, including (a) the pH value, (b) the salt concentration, (c) the solid loading, (d) the extrusion rate (cm3/sec), and (e) drying speeds (static air drying or flowing air drying). To avoid phase separation, we will design the orifice size according to the GN size. For the activated carbon slurries, we also investigated the aqueous system and the micro-extrusion performance.
Eta6 chemical Modification of Epitaxial Graphene: An Avenue for Non Destructive Surface Functionalization and Atomic Layer Deposition
Authors: Che Songwei , Sreeprasad Theruvakkattil Sreenivasan , Nguyen Phong , Berry Vikas
Published: February 2020

Graphene is one atom thick planar sheet and has been applied in many fields due to its distinct properties, such as high carrier density, ballistic transport and high thermal conductivity.  Its superior properties are expected to further expand its electronic application by functionalizing graphene with other moieties. However, in most cases functionalization leads to the conversion of planar hybridized sp2 state to tetrahedral sp3 state. This conversion results in the increased carrier scattering and reduced carrier density. In this talk, we demonstrate a novel η6 functionalization route, where epitaxial graphene can react with Chromium hexacarbonyl solution at low temperature. Raman spectroscopy and X-ray photoelectron spectroscopy are employed for surface characterization. Two Chromium peaks exist in XPS confirming (a) the grafting of chromium tri-carbonyl on the graphenic aromatic rings, and (b) interaction between the pi-cloud of graphene and the d-orbital of Chromium. The Raman 2D-peak blue shifts indicating back donation between Chromium and carbon rings. There is no D-band in Raman spectroscopy showing the sp2 carbon character in the lattice is preserved. Besides, the electrical properties of functionalized graphenes and their application in sensing will also be discussed. The results clearly show that its superior properties including high carrier density, low carrier scattering and high sensitivity are maintained.
Fundamental Studies of Iron Redox Flow Battery Electrochemistry in a Deep Eutectic Solvent
Authors: Miller Mallory A. , Wainright Jesse S. , Thompson Levi T , Savinell Robert F.
Published: February 2020

Current redox flow battery (RFB) technologies are limited by low energy and power densities; thus, a recent focus has been on non-aqueous electrolytes. Although organic solvents allow for increased voltage windows, they possess a sensitivity to moisture, low active species solubilities, high flammability and toxicity, and limited availability. Another class of non-aqueous solvents, ionic liquids (IL) or more specifically, deep eutectic solvents (DES) offer promise for future non-aqueous RFBs. These “designer solvents” can be created using a number of combinations of bulky asymmetric cations and weakly coordinating anions, allowing for the ability to tailor different solvent properties, presenting an opportunity to generate optimized solvents. DES are advantageous in that they have large electrochemical windows similar to organic solvents, and they have low volatilities, high thermal stabilities, high polarities, and high conductivities without the need for a supporting electrolyte [1-4]. They offer a “greener” alternative to volatile organic solvents and are non-toxic and nonflammable [5, 6]. Two different deep eutectic systems, reline (1:2 molar ratio choline chloride and urea) and ethaline (1:2 molar ratio choline chloride and ethylene glycol), have been investigated as well as an iron eutectic (1:3 molar ratio iron chloride and ethylene glycol). Wide potential windows of 2.6V and 2.0V are achieved using reline and ethaline respectively (compared to 1.23V for aqueous). Electrolyte properties such as conductivities and viscosities as a function of temperature are reported. Iron plating efficiencies are reported; higher coulombic efficiencies compared to the aqueous system are attributed to elimination of the side reaction of hydrogen evolution (due to the expanded voltage window). Characterization of the electrokinetics, diffusion coefficients, and solubility of the iron chemistry at 50°C have been determined using voltammetric measurements and electrochemical impedance spectroscopy at platinum, glassy carbon, and carbon fiber microelectrodes. Iron was chosen as proof of concept chemistry; higher potential couples are currently under investigation. 

[1]       S.-H. Wu, Thermochimica Acta, vol. 544, pp. 1-5, 2012.

[2]       G. A. Baker, S. N. Baker, S. Pandey, and F. V. Bright, Analyst, p. 800, 2005.

[3]       T. Welton, Chem Rev., p. 2071, 1999.

[4]       S. A. Forsyth, J. M. Pringle, and D. R. MacFarlane, Aust J. Chem, vol. 57, 2004.

[5]       M. J. Earle and R. K. Seddon, Pure Appl. Chem., vol. 72, p. 1391, 2000.

[6]       K. N. Marsh, A. Deev, A. C.-T. Wu, T. E., and A. Klamt, Korean J Chem. Eng. , vol. 19, 2002.

Figure 1
Lithium Ion Dynamics in Amorphous Li-Si Electrochemically Prepared from Semiconductor Grade, Monocrystalline Silicon - an NMR Study about Local Structures and Li+ Self-Diffusivity
Authors: Dunst Andreas , Sternad Michael , Epp Viktor , Wilkening Martin
Published: February 2020

Silicon is one of the most promising anode materials for lithium-based rechargeable batteries. Provided the volume changes during Li uptake can be brought under control, Li ion diffusivity is expected to crucially determine the performance of such energy storage systems. Therefore, studying diffusion properties in amorphous Li-Si underpins applied research that is being directed towards the development of powerful storage devices. So far, only little information is available on Li self-diffusion in amorphous Si. Here, we used 7Li NMR spectroscopy [1] to precisely quantify microscopic activation energies and Li jump rates in amorphous Li-Si which is primarily formed if monocrystalline Si is lithiated electrochemically. Our results reveal relatively fast Li diffusivity with an average activation energy for long-range ion transport as high as ca. 0.65 eV; jump rates turn out to be in the order of 2.5 × 105 1/s at 246 K, see also ref. [2]. Comparisons with data from laboratory frame NMR relaxometry, which is sensitive to more localized ion hopping, points to complex dynamics that is most likely governed by non-exponential motional correlation functions originating from a large distribution of activation energies. Noteworthy, a second sample, which is a mixture of amorphous Li-Si and metastable, crystalline Li15Si4 that forms at lower discharge potentials, points to slightly enhanced Li diffusivity (0.51 eV). Interestingly, ﬁrst high-resolution 6Li MAS NMR experiments on X-ray amorphous Li-Si, which have been carried out using isotope enriched samples, indicate the presence of structural motifs that resemble those of Li12Si7. The data obtained might help optimizing Li-based silicon batteries whose performance critically depend on fast Li-ion transport.

 

Acknowledgement  Financial support by the Federal Ministry of Science, Research and

Economy and the National Foundation for Research, Technology and Development is gratefully acknowledged.

 

References

[1]   V. Epp, M. Wilkening, Phys. Rev. B 82 (2010) 020301.

[2]   A. Kuhn, P. Sreeraj, R. Pöttgen, H.-D. Wiemhöfer, M. Wilkening, P. Heitjans, J. Am. Chem. Soc. 113 (2011) 11018.
Carbon-Coated Mesoporous SiOx Using an Oil Templating As a High Capacity Anode Material for Lithium-Ion Battery
Authors: Park Eunjun , Lee Jaewoo , Kim Dae Sik , Jeong Goojin , Park Min-Sik , Kim Young-Jun , Kim Hansu
Published: February 2020

Si based anode materials for lithium-ion batteries have gained much attention due to its high theoretical capacity (3,580 mAhg-1). However, Si anode materials have critical limit to commercial use because of poor cycle performance associated with severe volume changes during cycling. To solve this problem, various approaches have been suggested. In particular, porous structure of Si materials would be helpful for improvement of cycle performance. In this work, C-coated mesoporous SiOx nanoparticles were prepared as anode materials for lithium-ion batteries using a sol-gel reaction of Si precursor with oil templates. The hydrophobic oil, pore former, was uniformly distributed into the SiOx precursor. After heat treatment under reducing atmosphere, the residual oil was contributed to form the carbon layer, which would be assisted to improve electrical conductivity of active materials, on the surface of SiOx matrix. The C-coated mesoporous SiOx nanoparticles showed a reversible capacity of 730 mAhg-1 at current density of 200 mAg-1 with stable cycle performance over 100 cycles and high rate capabilities. The microstructure and electrochemical properties of the C-coated mesoporous SiOx nanoparticles will be discussed in more detail.
Characterization of Carbon Black Particles for Use in Aqueous Slurry Electrodes
Authors: Hoyt Nathaniel C , Agar Ertan , Nagelli Enoch A. , Savinell Robert F , Wainright Jesse S.
Published: February 2020

Flowable slurry electrodes have received renewed interest in recent years for use in electrochemical systems. Applications include, but are not limited to, electrochemical energy storage (e.g. flow batteries1,2 and electrochemical flow capacitors3) and desalination (e.g. flow electrode capacitive desalination systems4). All of these applications share similar, but distinctly different, requirements for the solid constituent of the slurry. For example, some systems might favor high electronic conductivity while others could place more of a premium on possessing a high specific surface area.

Carbon particles are often used as the solid constituent in these slurries as they often possess high values of both of these desirable properties. Carbons slurries examined in past research have included activated carbons, carbon blacks, and other more exotic carbons (multi-walled carbon nanotubes, graphene, etc.)5. The selection of slurry constituents inevitably involves trade-offs, however. While activated carbons may possess high specific areas, slurries composed of these particles have low conductivities. Conversely, highly conductive carbons generally do not possess high specific areas. For any of these particles, if the surface chemistry does not permit high loadings, then both the specific area and the conductivity are likely to suffer.

In this presentation we will discuss how the optimal selection of slurry properties varies depending on the given application in which the slurry electrode is intended to be used. The slurry properties of a wide array of different carbon black particles in aqueous electrolytes will also be presented, and good candidates for use in specific electrochemical systems will be discussed.

[1] M. Duduta, B. Ho, V. Wood, P. Limthongkul, V.E. Brunini, W.C. Carter, Y.M. Chiang, Advanced Energy Materials, 1, 511-516 (2011)

[2] T. Petek, N. Hoyt, J. Wainright and R. Savinell, "Slurry Electrodes for Iron Plating in an All-Iron Flow Battery," submitted to J. Power Sources, 2015.

[3] V. Presser, C. Dennison, J. Campos, K. Knehr, E. Kumbur, Y. Gogotsi, Advanced Energy Materials, 2, 895-902 (2012)

[4] S. Jeon, H. Park, J. Yeo, S. Yang, C.H. Cho, M.H. Han, D.K. Kim, Energy Environ. Sci., 6, 1471 (2013)

[5] M. Youssry, L Madec, P. Soudan, M. Cerbelaud, D. Guyomard, B. Lestriez, Phys. Chem. Chem. Phys., 15, 14476 (2013)
Manganese-Based Redox Flow Batteries for Grid Energy Storage
Authors: Swartz Christopher R , Lipka Stephen M , Long Katelyn F. , Kodenkandath Thomas
Published: February 2020

Redox flow batteries (RFBs) are secondary battery systems suitable for large-scale, stationary energy storage applications, and are capable of storing large quantities of energy (MWh) and power (MW).1 One principle advantage of flow batteries is the ability to decouple energy and power density, and scale both independently. The all-vanadium RFB represents the current state-of-the-art in flow battery technology, but uses expensive ion exchange membranes including Nafion®, and the relatively high cost of vanadium leads to expensive electrolytes.2

The development of manganese-based anolytes as a suitable alternative to vanadium anolytes for redox flow batteries is attractive for various reasons, including a higher reversible potential for Mn2+/Mn3+ than VO2+/VO2
+, higher natural abundance, and lower cost than vanadium. Flow battery anolytes based on the Mn2+/Mn3+ redox couple have been reported in the literature, and the high standard electrode potential of Mn2+/Mn3+ (1.51 V) has been utilized in manganese anolyte (Mn2+/Mn3+)/vanadium catholyte (V2+/V3+) redox flow batteries, featuring a theoretical open circuit voltage of 1.77 V.2,3 The usage of manganese anolytes can lead to a higher cell voltage, yet the disproportionation reaction of Mn3+ is a technical hurdle that needs to be resolved in order for manganese-based anolytes to find widespread utility in redox flow batteries.2,4

This presentation will disclose investigations on the development of manganese-anolyte based redox flow batteries, and will show results from two different systems, including Ti/Mn, and V/Mn. Half–cell and full cell performance metrics, including cycle life testing, will be presented for each system.

References

1) Wang, W. et al. J. Power Sources.
2012, 216, 99.

2) Xue, F.-Q. et al. Electrochimica Acta.
2008, 53, 6636.

3) Hong, T.; Xue, F. “Investigation on manganese (Mn2+/Mn3+)-vanadium (V2+/V3+) redox flow battery.” 2009 Asia-Pacific Power and Energy Engineering Conference (APPEEC).

4) Swartz, C. R.; Lipka, S. M.; Rogers, F. III; Chen, R.; Kodenkandath, T. “Aqueous Manganese-Based Electrolytes for Redox Flow Batteries.” ECS abstract MA2014-02, 616.
Model-Based Techno-Economic Analysis of Battery Function for Energy Storage of Solar Energy
Authors: Lawder Matthew T , Subramanian Venkat
Published: February 2020

By its nature solar power is intermittent. Because the amount of solar power generation cannot be controlled the economic value energy from a solar array is devalued. Adding energy storage can remove the intermittent nature of solar power (see figure 1), but will increase the overall cost of electricity supplied from the system. The model developed for this study analyzes the operational characteristics and economics of adding a battery system to solar arrays in different regions around the country. The technologic and economic benefits of battery systems are assessed on an individual site basis.

A system level model includes a battery component based on electrochemical and transport principles, a solar array that accounts for site-based irradiance patterns, and a dispatch and control structure that controls the flow of power between generation and demand [1]. The battery component is the focus of the system level model and is studied to understand how the battery will function under dynamic application cycling. The irradiance data for US sites was obtained from the NREL MIDC database which contains minute resolution irradiance data for all the sites studied [2]. The battery model includes a study of how variation in irradiance will affect capacity fade by including fade side reactions into the model.

Metrics studied include battery sizing, battery utilization, battery degradation, system autonomy, solar energy utilization. Additionally, the economic value of systems were studied based on time-of-use pricing scenarios to determine break-even points for adding battery to solar arrays for non-utility customers. The economic analysis is informed by the battery utilization and system autonomy studied in the model. Comparisons of individual sites and solar+battery systems were studied. These model-based studies are important for determining the utility of batteries in conjunction with renewable applications.

Acknowledgements

The authors acknowledge financial support from the U.S. Department of Energy’s Advanced Research Projects Agency- Energy (ARPA-E), and the Solar Energy Research Institute in India and the United States (SERIIUS), as well as, Washington University in St. Louis’ McDonnell Academy Global Energy and Environmental Partnership (MAGEEP).

References

1. S. Santhanagopalan, Q. Z. Guo, P. Ramadass, and R. E. White,  Journal of Power Sources,
156, 620(2006)

2. National Renewable Energy Laboratory. (2014, 2014). Measurement and Instrumentation Data Center (NREL). Available: http://www.nrel.gov/midc/

Figure 1
Design Principles for Green Energy Storage Systems
Authors: Arbabzadeh Maryam , Johnson Jeremiah X. , Keoleian Gregory A.
Published: February 2020

Grid-scale energy storage systems represent a potential solution for several grid applications such as renewables integration and transmission and distribution upgrade deferral. The integration of these technologies into the grid can lead to different environmental outcomes. System characteristics that influence outcomes include renewable penetration, the existing grid power mix, and electricity demand characteristics. New frameworks are required to provide a robust way to assess the environmental impacts and key trade-offs that emerge when considering energy storage options to inform design and technology selection and improve sustainability performance of the grid. To achieve this, we develop fundamental green design principles specific to grid-connected energy storage, coupled with a systematic and robust sustainability assessment algorithm to inform decision makers, designers and operators. These principles address key issues such as material sustainability, service life, and environmental performance of grid generations’ assets. An algorithm is developed to deploy the design principles of energy storage systems that meet various grid applications. This process takes into account the service that the energy storage would provide. Energy storage applications range from distributed power for built environment to large scale energy storage applications such as renewables integration, ancillary services, time shifting, electric supply capacity, renewable energies capacity firming and micro-grid capability. Each application has specific requirements. For example, ancillary services require bulk capacity in order to keep power system quality, reliability and security (Eyer and Corey 2010). In this algorithm, the potential alternatives (including energy storage) are screened to satisfy performance requirements and sustainability criteria in meeting a specific application. Life cycle assessment (LCA) methods are applied to evaluate environmental sustainability performance. Vanadium redox fellow batteries (VRFBs) utilization in an off-grid configuration is analyzed as a case study to demonstrate the application of selected principles. 

References

Eyer, J and Corey, G. 2010. Energy storage for the electricity grid: benefits and market potential assessment guide. Sandia National Laboratories.
Structurally Tailored Polyanion Deficient LiFePO4 As Cathode Materials for Li-Ion Batteries
Authors: Back Changkeun , Noh YoungBae , Cho YoungJae
Published: February 2020

In this work, structural tailing of LiFePO4 as cathode material for Li-ion batteries from purposely induced polyanion deficiency in its structure and followed effects in terms of structure and electrochemical properties will be discussed. It has been found that while the native defect of PO4
3- polyanion in LiFePO4 compound is thermodynamically preferred to the generation of point defects of P and O, the degree of polyanion deficiency in the range of X =0.05~0.09 in LiFe(PO4)1-x is structurally stable. The polyanion-deficient LiFePO4 has an uniformly dispersed locally distorted crystalline structure with an increased lattice volume, which is accounted as calculated by first-principal method to be resulted from an expanded bond length between the chemical elements and twisted bond angle due to charge polarization around P and O defect sites. In further, weakening of the bond strength between Li-O results in lowering an activation barrier for Li ions to pass through one site to next neighbored sites, which help increase Li-ion kinetic property in the structure. In experimental test, while electrochemical cycle of poly-anion deficient LiFePO4 is very stable with less increment of impedance upon the cycling as compared to that of the others, rate performance is superior, as well. Experimental measurements of electronic and ionic conductivities using cyclic voltammetry and impedance spectroscopy on poly-anion deficient LiFePO4 supports the results as the kinetic properties of Li ions and electron are greatly improved.

Figure 1
A New Guide for Searching High-Performance Catalysts for Direct Alcohol Fuel Cells
Authors: Yang Yongan , Yang Yangzhi
Published: February 2020

Direct alcohol fuel cells (DAFCs) are important power sources for distributed energy applications, such as automobiles.  They are superior to combustion engines in lower operation temperatures and to hydrogen fuel cells in higher energy density and ease of fuel-handling.  Two of major issues are the elucidation of the multi-electron oxidation mechanism and the development of high-performance (activity, selectivity, stability) electrocatalysts.  For over two decades, cyclic voltammetry has been used as a convenient and powerful tool to assess catalysts’ performance.  The oxidation peak in the backward scan is assigned to the oxidation of intermediate carbonaceous compounds (mainly CO) that are formed in the proceeding forward scan.  Thus, the ratio of peak intensity in the forward and backward scans (If/Ib) is believed to indicate the tolerance of CO poisoning; the higher the If/Ib, the better the tolerance. This figure-of-merit has been applied ever since for searching high-performance catalysts, including the Pt-based materials for acidic cells and Pd-based materials for alkaline cells.  However, to date, catalysts that are practically superior to commercial counterparts have not been identified yet.

In this presentation, we will provide direct and unambiguous evidence to show that 1) the backward oxidation peak is not due to the oxidation of intermediate carbonaceous compounds that are formed in the proceeding forward scan; 2) the ratio If/Ib has nothing to do with the CO oxidation and a higher Ib/If value can indicate superior capability in surface regeneration.  These findings are applicable to Pt in acidic cells, Pd in alkaline cells, and various alcohols.

Our discovery corrects a long-term misunderstanding on the reaction mechanism of catalytic electroxidation of alcohols, provides a new guide for searching high-performance catalysts, and has the potential to be generalized to other fields of electrocatalysis.
Density Functional Theory and Conductivity Studies of Boron-Based Anion Receptors
Authors: Leung Kevin , Fenton Kyle R , Rempe Susan , Chaudhari Mengash , Pratt Harry , Staiger Chad , Nagasubramanian Ganesan
Published: February 2020

Anion receptors that bind strongly to fluoride anions in organic solvents can help dissolve the lithium fluoride discharge products of primary carbon monouoride (CFx) batteries, thereby preventing the clogging of cathode surfaces and improving ion conductivity. The receptors are also potentially beneficial to rechargeable lithium ion and lithium air batteries. We apply Density Functional Theory (DFT) to show that an oxalate-based pentauorophenyl-boron anion receptor binds as strongly, or more strongly, to uoride anions than many phenyl-boron anion receptors proposed in the literature. Experimental data shows marked improvement in electrolyte conductivity when this oxalate anion receptor is present. The receptor is sufficiently electrophilic that organic solvent molecules compete with F
-
for boron-site binding, and specific solvent effects must be considered when predicting its F
-
affinity. To further illustrate the last point, we also perform computational studies on a geometrically constrained boron ester that exhibits much stronger gas-phase affinity for both F
-
and organic solvent molecules. After accounting for speci_c solvent effects, however, its net F
-
affinity is about the same as the simple oxalate-based anion receptor. Finally, we propose that LiF dissolution in cyclic carbonate organic solvents, in the absence of anion receptors, is due mostly to the formation of ionic aggregates, not isolated F
-
ions.

Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corpo ration, for the U.S. Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Figure 1
Alkaline Hydrogen-Iodine Reversible Fuel Cell
Authors: Nguyen Trung Van , Yarlagadda Venkata , Konwar Dhrubajit
Published: February 2020

We have considered the acid-based H2-I2 fuel cell along with the acid-based H2-Br2 fuel cell as potential systems for electrical energy storage. However, we decided not to pursue the H2-I2 system because of its low cell open circuit potential (0.54V), even though the HI-I2 environment is more benign than the HBr-Br2 environment.  Recently, we found that by operating the hydrogen reactions in an alkaline medium we could shift the electrode standard reduction potential from 0V to -0.83V which combined with the bromine electrode standard reduction potential of 1.09V increases the cell potential of an alkaline H2-Br2 fuel cell from 1.09V to 1.92V [1].  This 0.83V shift in the hydrogen electrode potential motivated us to take another look at the alkaline H2-I2 system because of the higher cell potential (1.34V). See Figure 1. This presentation will discuss the alkaline H2-I2 system, its advantages and disadvantages, and recent development by our group at the University of Kansas.

Reference:

T.V. Nguyen, V. Yarlagadda, G. Lin, G. Weng, C.-Y.V. Li, and K.-Y Chan, “Comparison of Acid and Alkaline Hydrogen-Bromine Fuel Cell Systems,” ECS Transactions, 58, No. 37, 29-35 (2014).

Acknowledgements

This work was funded by the National Science Foundation under Grant No. EFRI-1038234.

Figure 1
A Dual-Mode Rechargeable Lithium-Bromine/Oxygen Fuel Cell
Authors: Bai Peng , Viswanathan Venkatasubramanian , Bazant Martin Z.
Published: February 2020

Increasing global energy demand has driven the exploitation of oil reservoirs in deep oceans. The high risk of oil spill due to unexpected failures of undersea facilities urges the deployment of autonomous underwater vehicles (AUV) for frequent and thorough inspections in these extreme environments that humans cannot easily access. To meet the long endurance and occasionally high power requirements of the AUV, we propose a lithium-bromine/oxygen fuel cell with a protected lithium metal anode to provide high specific energy at either low-power mode with seawater (oxygen) or high-power mode with bromine catholytes. The proof-of-concept fuel cell with a flat catalyst-free graphite electrode can discharge at 3mW/cm2 with seawater, and 9mW/cm2 with dilute bromine catholytes. The fuel cell can also be recharged with LiBr catholytes efficiently to recover the lithium metal anode. Scanning electron microscopy images reveal that both the organic electrolye and the bromine electrolyte corrode the solid electrolyte plate quickly, leading to nanoporous pathways that can percolate through the plate, thus limiting the cell performance and lifetime. With improved solid electrolytes or membraneless flow designs, the dual-mode lithium-bromine/oxygen system could enable not only AUV but also land-based electric vehicles, by providing a critical high-power mode to high-energy-density (but otherwise low-power) lithium-air batteries.