bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual-Functional Polymer Coating on Lithium Anode for Suppressing Dendrite Growth and Polysulfide Shuttling in Li–S Batteries
Authors: Luo Jing , Wu Nae-Lih
Published: February 2020

Rechargeable Li–S batteries using Li metal as the anode and S as the cathode-active material are attractive energy storage candidates because the couple offers high specific capacities and possesses marketing advantages such as the light weight of Li and low cost of S. However, the commercialization of Li–S batteries remains hindered by several technical hurdles of both the S cathode and Li anode. The multistep electrochemical reactions of the S cathode involve various Li polysulfide intermediates (Li2Sn, 3 ≤ n ≤ 8), some of which are highly soluble in aprotic organic electrolytes. The diffusion of these soluble polysulfides to the Li anode, also known as the polysulfide-shuttling effect, causes a series of problems including self-discharge, loss of active material, and corrosion of the Li anode. Meanwhile, metallic Li anodes are susceptible to the accumulation of dendritic Li deposits on their surfaces because of uneven Li-ion transport on the electrode surface during repeated charge–discharge cycles. This detrimental accumulation can cause low Columbic efficiency and even a short circuit, triggering thermal runaway and even battery explosions.

 Although the use of artificial coatings or membranes on Li anode surface has been suggested as a promising approach for suppressing Li dendrite formation, no previous study has simultaneously addressed Li dendrite formation and polysulfide-shuttling. In Li–S batteries, lithium nitrite (LiNO3) has been widely used as an electrolyte additive for maintaining stable anode performance by inhibiting the reactions between polysulfides and the Li surface. However, the long-term feasibility of LiNO3 is limited by its continuous consumption during battery operation. In this presentation, we report the successful development of a cation-selective and dimension-stable coating that can simultaneously suppress Li dendrite and polysulfide shuttling on the Li anode surface
Highly Stable Lithium Anode Protected with Conformal Aluonce for High Mass-Loading Li-S Batteries
Authors: Chen Lin , Huang Zhennan , Shahbazian-Yassar Reza , Libera Joseph A. , Klavetter Kyle , Zavadil Kevin R , Elam Jeffrey W
Published: February 2020

Lithium metal as an ideal anode for next-generation batteries has attracted extensive attention. However, rough electrodeposition, severe parasitic reactions and uncontrolled lithium dendrites cause fast battery fading. Engineering a dendrite-free lithium metal anode for long cycling life is critical for its future development. Here, we reported a conformal, aluminum-based polymer coating with highly crosslinking structure on lithium using molecular layer deposition (MLD) to control undesirable reactions. This hybrid organic/inorganic film functions as an artificial interface to stabilize lithium stripping/deposition and enables minimal side reactions and dendrite-free lithium anodes. Alucone coated Li leaded to several times longer cycle life in a large current rate and achieved steady Coulombic efficiency of 99% at 0.4 mA/cm2. The protected Li also accomplished much improved performance of lithium-sulfur (Li-S) batteries with a high mass-loading of ~5 mg/cm2. Our proposal and findings offer an efficient avenue towards a highly stable lithium anode and the application in high energy density Li-S batteries.
The Role of the Carbon-Matrix in the Performance of Lithium-Sulfur Cell
Authors: Agostini Marco , Lim Du-Hyun , Matic Aleksandar
Published: February 2020

Li-battery technology is today mainly developed as small energy delivery systems for portable devices.
1
However, in recent years the growing interest in renewable energy and in electric vehicles exploiting electric power requires the development of new, high capacity and long life batteries.
1
In this context Li-S battery technology became of great interest due to the high theoretical energy density of 3500 Wh kg-1, estimated to lead to 3-5 times increase in practical energy density compared to commercial Li-ion battery today available.
2

Even though the Li/S battery system has been widely investigated, several issues related to the lithium-sulfur electrochemical reaction still hinder the practical realization of this technology. Indeed, the electrochemical reaction mechanism involves a series of steps with formation of soluble polysulfide species.
3
This dissolution leads to the loss of active material from the solid electrode and to the “shuttle effect” of the polysulfide with consequent capacity reduction and limited cycling-life of the battery. Furthermore, sulfur has a very low electronic conductivity thus requiring the addition of a conducting matrix.

In this contribution we present the role of the carbon-matrix on the performance of Li-S cells based on liquid and solid electrodes. Various carbon and carbon-sulfur compounds have been taken into account and investigated. We demonstrated how the surface area, the pore structure and the free volume in the electrode are the significant driving forces to improve the Li-S electrochemical reaction.

References

(1) B. Scrosati, J. Garche, J. Power Sources. 195 (2010) 2419-3046.

(2) Y. Yang, G. Zheng, Y. Cui, Energy Environ. Sci.6 (2013) 1552-1558.

(3) X. Ji, L.F. Nazar, J. Mater. Chem. 20 (2010) 9821−9826.
Demonstration of Carbon-Free Lithium-Ion Redox Flow Couple
Authors: Qi Zhaoxiang , Koenig Gary
Published: February 2020

Redox flow batteries have been actively researched in part because of the key advantage to independently design and adjust the power and energy of the system. The most common redox flow batteries are transition metals dissolved in aqueous solvent, and these batteries have energy density limitations caused by the solubility of the active species in the electrolyte. Semi-solid flow batteries have recently been reported as an alternative, where high energy density was achieved by incorporation of lithium-ion active material solid particles as the energy storage media accompanied with carbon additives to provide a conductive network. A challenge with these semi-solid flow batteries is the high viscosity of the flowing slurry, which results from the interconnected carbon network. In this presentation, we will describe a new type of flow battery comprised of flowing suspensions of carbon-free lithium-ion active materials in the electrolyte. The electrochemical reactions occur during collisions of active material particles with the current collectors. We will demonstrate proof-of-concept for both half-cells and full-cells in custom geometries using multiple electrochemical testing techniques.
A Steric Approach to Modifying Redox Potentials
Authors: Elliott Corrine F , Casselman Matthew D , Modekrutti Subrahmanyam , Risko Chad , Odom Susan A
Published: February 2020

Many of the electrochemical energy-storage systems under consideration for large-scale power storage and allocation rely on stable electroactive materials to shuttle and/or store charge. Here we seek to design a new class of organic compounds, based on the electroactive molecule phenothiazine, for use as (a) redox-shuttle additives to mitigate excess charge in overcharging lithium-ion batteries, and (b) catholyte materials for use in redox flow batteries. This presentation will include the results of density functional theory calculations that are used to model the physicochemical effects of substituent identity and placement on phenothiazine by introducing electron-donating and/or -withdrawing substituents at strategic positions around the heterocyclic core. Substituent crowding is shown to effect changes in oxidation potential at odds with those anticipated from Hammett constants, as well as changes in energetically optimal conformations, consistent with more-restricted relaxation pathways afforded by the additional steric strain. A subset of the compounds under consideration were subsequently selected for synthesis and electrochemical analysis. The results of this testing suggest that, unlike prior methods of increasing oxidation potentials using electron-withdrawing groups, strategic placement of substituents can be exploited to raise oxidation potentials without raising reduction potentials, thereby preventing access to reduction decomposition pathways. The results of this analysis reveal strategies for designing and tuning the properties of new electroactive compounds for energy-storage applications and beyond.
Synthesis of Graphene Nanosheets for the Energy Sector By Electrochemical Exfoliation of Graphite in Sulfonated Ionic Liquids
Authors: Cuara-Diaz Edgar , Morales-Acosta Diana , Fernández Tavizón Salvador , Benavides Roberto
Published: February 2020

Graphene has gained increasing attention of the scientific community due to its properties and wide range of applications many beneficial properties. One of the most promising applications is as electrode material for the production of energy in fuel cells and Lition-ion batteries. Various synthesis procedures has been developed but most of them are unable to generate graphene flakes in bulk, in addition, it usually takes several hours to synthetize a batch, requires high temperatures and produce several sub-products, some of them toxic. The electrochemical synthesis of graphene provides a facile, fast, scalable, economic and environmental friendly pathway to the production of graphene flakes. In this work, we analyze the properties of electrochemical exfoliated graphite using different sulphonated ionic liquids as reactant media. The graphene sheets were synthetized via electrochemical methods by intercalation, oxidation and reduction of graphite bar. The physicochemical properties of the generated graphene were evaluated trough TEM, SEM and FT-IR and Raman spectroscopies. Our results show that synthesis by ionic liquids allows a better control on the physical properties of the graphene sheets compared to the traditional synthesis such as the Hummers method.
(Invited) SWCNT:C60 Solar Cells from Aqueous Separation Techniques
Authors: Flavel Benjamin S
Published: February 2020

In our work we develop new methods to scale-up aqueous separation techniques for the fabrication of inks and large area thin films of carbon nanotubes. This allows us to study the interaction of polymer-free single chirality and polychiral mixtures of nanotubes with acceptors such as C60 for energy applications such as solar cells. We are using transfer matrix calculations to theoretically calculate the optimal layer thicknesses within a nanotube solar cell and show that light absorption can be tailored to nanotube’s primary (S11) or secondary (S22) absorption peak, or a combination thereof. Upon using large diameter, (9,8), and mixtures of carbon nanotubes we then investigate the required net driving energy for SWCNT exciton dissociation onto C60 and establish a family of (n,m) species that can efficiently be utilized in polymer-free SWCNT:C60solar cells. Possible strategies to extend this diameter limit are discussed.

[1] M. Pfohl, K. Glaser, A. Graf, A. Mertens, D. Tune, T. Puerckhauer, A. Alam, L. Wei, Y. Chen, J. Zaumseil, A. Colsmann, R. Krupke, B. S.Flavel, Probing the Diameter Limit of Single Walled Carbon Nanotubes in SWCNT:Fullerene Solar Cells, Advanced Energy Materials, 6, 2016, 16008900 . DOI: 10.1002/aenm.201600890

[2] M. Pfohl, K. Glaser, J. Ludwig, D. D. Tune, S. Dehm, C. Kayser, A. Colsmann, R. Krupke, B. S. Flavel, Performance Enhancement of Polymer-Free Carbon Nanotube Solar Cells via Transfer Matrix Modeling, Advanced Energy Materials, 6 2016 1501345. DOI: 10.1002/aemn.201501345.
Diameter-Dependent Excitation Energy Transfer for Enhanced Semiconducting Single-Walled Carbon Nanotube Solar Photoconversion
Authors: Ihly Rachelle , van Bezouw Stein , Arias Dylan , Cambre Sofie , Campo Jochen , Ferguson Andrew John , Johnson Justin C. , Wenseleers Wim , Blackburn Jeffrey L.
Published: February 2020

Tremendous progress and innovation has ushered the incorporation of semiconducting single-walled carbon nanotubes (s-SWCNTs) as active components into organic/inorganic/hybrid solar cells and thermoelectrics. For solar photoconversion, strong and tunable absorption is necessitated, suggesting that s-SWCNTs can play a role as light-harvesting components, however the narrow and distinct excitonic optical transitions found in s-SWCNT systems limit broad-band absorption. As such, we introduce encapsulation of small molecules within the endohedral volume of s-SWCNTs as a route to increase and extend light absorption in regions outside s-SWCNT excitonic transitions. Creation of this self-assembled supra-molecular system can strongly modify the opto-electronic properties of both the s-SWCNT and encapsulated molecule.

We investigate excitation energy transfer occurring from encapsulated dye molecules to s-SWCNTs, which results in luminescent SWCNT excitons. We exploit the high-throughput and chiral selectivity of polyfluorene wrapping methods to generate dispersions of s-SWCNTs with dye encapsulation. We demonstrate that the selectivity of the polyfluorene polymer for semiconducting chiral distributions is not affected by the presence of encapsulated molecules. Tracking the excited state transient absorption signatures of excitation energy transfer provides detailed information regarding dynamics of both the encapsulated dye and s-SWCNTs. We observe sub-picosecond excitation energy transfer of excitons generated in dye molecules to the surrounding s-SWCNTs. Photoluminescence excitation maps reveal that the absorption of encapsulated dye molecules depends sensitively on the diameter of the s-SWCNT in which they are encapsulated. We consider a simple molecular exciton model to describe aggregate formation within the s-SWCNT endohedral volume, which reveals that the dye molecules adopt unique aggregate structures that are defined both by a competition between intermolecular interactions between the dye molecules and confinement effects due to the s-SWCNT diameter. Small molecule encapsulation in s-SWCNTs serves as a strong platform to control intermolecular interactions in small molecule systems through confinement, which opens up the possibility of enhancing photo-induced extraction of energy and charge in s-SWCNTs solar photoconversion systems.
Fullerene-Grafted 3D Graphene As Electrical Energy Storage Material
Authors: Cerón Maira R. , Biener Monika M. , Campbell Patrick G. , Biener Juergen , Echegoyen Luis
Published: February 2020

Supercapacitors have the potential to replace Li ion batteries as the next-generation electrical energy storage technology in demanding applications due to their high power density and excellent cycling stability. Graphene-based supercapacitor electrodes are particularly promising because they feature high surface area, good electrical conductivity, and chemical inertness. Researchers at Lawrence Livermore National Laboratory have developed tailored fullerene-grafted 3D mesoporous graphene macro-assemblies (GMAs) (Figure 1) for electrical energy storage applications by anchoring fullerene molecules to the 3D graphene backbone. Fullerene-grafted graphene (C60-GMA) materials promise to overcome the current charge storage limitations of carbon-based supercapacitors by combining the high charge storage capacitance of fullerenes with the high electrical conductivity of 3D-GMAs. In fact, the charge storage capacitance of fullerene (223 mAh/g) is similar or higher than that of today’s standard lithium ion battery electrode materials (177 mAh/g for LiFePO4).

Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-017. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. IM Release Number LLNL-ABS-716277.

Figure 1. Fullerene-grafted 3D graphene bulk material

Figure 1
Direct Growth of Carbon Nanofibers on Nickel Foam and Its Application As Electrochemical Supercapacitor Electrodes
Authors: Sridhar Deepak , Omanovic Sasha , Meunier Jean-Luc
Published: February 2020

Carbon nanofibers (CNF) are useful for many applications such as polymer reinforcement, electrochemical devices like sensors, batteries, and supercapacitors. The most common method of producing them is by catalytic chemical vapor deposition (CVD) or by electrospinning. CNF growth using CVD is a single step process, unlike electro spinning which requires an additional carbonization step at higher temperatures. In CVD the catalyst is either incorporated directly onto the substrate or introduced with the feed gases. This adds extra cost and set limits to the design of the systems used for the CNF growth process, particularly in cases where porous structures are envisioned.

In supercapacitors, the electrode material is most often painted or deposited with an ink of carbon particles. Directly growing the carbon nanomaterial from the supporting surface would eliminate this step and allow complex geometries. It would also help in achieving a higher capacitance by removing the requirement of a binder material and eliminate the occurrence of agglomeration of the active material inherent in the ink deposition process. Another advantage is the higher conductivity of CNF compared to the commonly used active carbon material. With CNF growing directly of the current collector, the addition of conductive carbon black can possibly be eliminated. Finally, an increase access of the electrolyte to the electrode can be expected due to the natural 3-D nano-architecture formed by the CNF. On the other hand, the micro-scale 3-D structure of nickel foams have been the most sought after substrates (current collectors) in the battery and supercapacitor research as they offer more surface area for the deposition of the required active material, together with being non-corrosive in alkali medium. CNF grown directly on Ni-foams are thus expected to extend the performances of supercapacitor electrodes.

In this work, we have found a novel method of growing dense CNF on nickel foam. Cyclic voltammetry, galvanotactic charge discharge, and electrochemical impedance spectroscopy was made to electrochemically characterize these CNF/Ni-foam supercapacitor electrodes. When tested as a supercapacitor electrode in 6M KOH, our directly grown CNF gives a good aerial capacitance of about 60 mF/cm2 and an energy density of 16 mWh/m2. We believe this nickel foam with CNF to be very useful in supercapacitors and batteries in decreasing the resistance of the electrochemical device and provide additional surface area.
(Invited) Nanographenes and Their Self-Assemblies for Highly Efficient Energy Devices
Authors: Wang Hsing-Lin , Wu Gang , Tretiak Sergei , Yen Hung-Ju , Holby Edward F.
Published: February 2020

In recent years, the development of novel nanogrpahenes have drawn huge interests mainly because of their use in optical, electronic and energy devices. In our lab, we have developed syntheses of a series of 2D and 3D nanographenes with various functional groups attached to the edge of the nanographene basil planes. These nanographenes reveal long and short range orders in their self-assemblies. Such orders can be clearly visualized by high resolution TEM with well defined d-spacing between nanographene layers. These nanographenes are semiconductors with tunable electronic structures and processibility in organic solvents. We have demonstrated their use for optical and electronic devices. Among other potential application, these high-surface area nanographenes have an excellent cyclic durability and a much enhanced charge capacity as novel anode materials for LIBs. Moreover, theoretical charge capacity of these nanographenes exceeds 2000 mAh/g due to an increased edge to surface ratio and oxygen containing functional groups.

Figure 1
Nitrogen, Phosphorus Dual-Doped Ordered Mesoporous Carbon Electrocatalyst for Oxygen Reduction Reaction
Authors: Zhao Gang , Xu Jianbo , Zhao Tianshou
Published: February 2020

To investigate the role of P in the dual-doped carbon electrocatalyst for oxygen reduction reaction (ORR) in alkaline media, three samples are prepared by varying the doping orders of N and P. Results show the resultant N-POMC (first doped with P, then N) exhibits an outstanding activity for ORR in alkaline media. The reason lies in the orientation effect of the first doped P on the later doped N, by increasing the ratio of graphitic-N significantly, confirmed by our experimental and DFT calculation. In addition, our results prove that the amount of graphitic-N is important in improving the activity for ORR. The doping strategy in this work is applicable to c0-doping strategy in exploring the synergy effect of different dopants and improving activity for ORR.
(Invited) On the Non-Covalent Functionalization of Carbon Nanostructures for Biomolecule Immobilization
Authors: Ramasamy Ramaraja P.
Published: February 2020

Carbon nanostructure such as fullerenes, graphene and carbon nanotubes play an important role in biological electrochemistry as they serve as both immobilization supports for variety of biomolecules as well as act as nanostructured conductive carriers for transport of electrons to the active sites of the biomolecules. Accordingly, carbon nanostructures are used as conductive matrices in bioelectrochemical systems such as biosensors and biological fuel cells. Herein we report a specific type of biomolecule immobilization chemistry, which has had tremendous success towards the functionalization of carbon nanostructures with enzymes, antibodies, aptamers, cells, organelles and sub-organelles. The chemistry involves the use of a molecular cross-linker such as 1-pyrene butanoic acid-succinimidyl ester (PBSE), which contains an aromatic moiety and a covalent binding group on either sides of a long alkyl chain. The aromatic ring (pyrene or similar moiety) binds to the carbon nanotube or graphene non-covalently through the interaction of pi-pi bonds between the carbon nanostructure and the aromatic moiety. The interaction is strongly dependent on the material properties of the nanostructure such as chirality of nanotubes, curvature and electronic properties. The covalent binding group on the other end of molecular cross-linker is usually an amine-binding group such as succinimidyl ester. The interaction of the succinimidyl ester with the surface amines groups of enzymes, cell membranes and other biomolecules result in irreversible attachment of the cross-linker with the biomolecules resulting in a stable immobilization of biomolecules on carbon nanostructures. The presentation will discuss the strategies and methods to improve the stability of biomolecules on carbon nanostructures through this non-covalent functionalization.
Electrocuring Tissue Adhesives
Authors: Steele Terry WJ
Published: February 2020

The challenge remains on developing bioahesive formulations for tissue fixation. A recently invented electrically charged glue (known as electrocuring adhesive or voltaglue)[1] is being developed. Comparing with light (photocuring)[2], heat (thermocuring)[3], and chemical activation means, the electrocuring allows adhesive to be activated on-demand when an applied voltage potential is raised above a certain threshold. Such adhesive opens a plethora of commercially promising advances and one of them is used for replacing sutures when there is a need to join body tissues together during surgery.

Tissue adhesive requires high adhesion strength, non-toxic byproducts, ease of application onto wet substrates, and on-demand crosslinking. Such a bioadhesive is important for minimally invasive surgery (MIS). Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine (PAMAM) dendrimers, while incorporating carbon allotropes such as graphene and carbon nanotubes. The electrocuring adhesive is activated at -2V (Ag/AgCl), allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage is discontinued, crosslinking on tissues is immediately terminated, allowing tunable elasticity and adhesive strength as crosslinking initiation and propagation are observed to be voltage and time dependent. The electrocuring adhesive has immediate implications in manufacturing and development of implantable devices and bioadhesives and offers a new route towards addressing current surgical challenges.

 

 

References

 

[1] J. Ping, F. Gao, J.L. Chen, R.D. Webster, T.W.J. Steele, Adhesive curing through low-voltage activation, Nature Communications 6 (2015).

[2] J.P. Fisher, D. Dean, P.S. Engel, A.G. Mikos, Photoinitiated Polymerization of Biomaterials, Annual Review of Materials Research 31 (2001).

[3] Y.-J. Park, D.-H. Lim, H.-J. Kim, D.-S. Park, I.-K. Sung, UV- and thermal-curing behaviors of dual-curable adhesives based on epoxy acrylate oligomers, International Journal of Adhesion and Adhesives 29 (2009).
(Invited) Synthetic Protein Recognition Using Fluorescent Single-Walled Carbon Nanotubes
Authors: Bisker Gili , Strano Michael S
Published: February 2020

The ability to specifically and selectively recognize, detect, and monitor molecules of interest is essential for many biomedical applications, and is a crucial element in innumerable biological and chemical processes. Recently, a new concept for generating synthetic recognition sites was introduced, namely, Corona Phase Molecular Recognition (CoPhMoRe). In this approach, a heteropolymer is adsorbed onto the surface of an optically active nanoparticle, forming a structured 3-dimensional corona around it, such that it can selectively and specifically recognize a target molecule. The adsorbed polymer does not necessarily have any affinity towards the target analyte, but rather its pinned configuration when folded onto the particle scaffold forms a recognition site. This generic scheme has been demonstrated using fluorescent single walled carbon nanotubes (SWCNTs) as the underlying nanoparticles for optical signal transduction, monitoring spectral response of their fluorescence emission to reveal analyte adsorption onto the SWCNT corona. Initial demonstrations of SWCNT based CoPhMoRe include corona phases selective towards small molecules. In this talk, I will describe the first protein-targeted CoPhMoRe, where a phospholipid-PEG corona is shown to render the SWCNT a sensor for fibrinogen, the building block of blood clots. The fibrinogen recognition also occurs in serum environment, at the clinically relevant fibrinogen concentrations in the human blood. These results open new avenues for synthetic, non-biological antibody analogues that recognize biological macromolecules, and hold great promise for medical and clinical applications.
Cellular Targeting of Carbon Nanotubes By Helical Polymers
Authors: Budhathoki-Uprety Januka , Langenbacher Rachel E , Jena Prakrit Vaibhav , Heller Daniel A
Published: February 2020

Tumors constitute many different cell types including epithelial cells, endothelial cells, fibroblasts, and macrophages. Endothelial cells form a barrier for nanomaterial delivery to tumors and other disease sites. Dysregulation in endothelial cells is associated in many pathological conditions including cancers. Nanoscale probes that can localize to specific endothelial cells may facilitate the understanding of disease processes. Single-walled carbon nanotubes (SWCNTs) are ideal tools for bio-imaging due to their non-bleaching photoluminescence in the near infrared region and molecular sensing capabilities that stem from environmental sensitivity of their optical bandgap. We non-covalently ‘cloaked’ carbon nanotubes with helical polycarbodiimide polymers to develop water soluble, biocompatible optical nanoprobes. We found that the use of different polycarbodiimide substituents modulated the surface chemistry of the carbon nanotubes to regulate uptake by epithelial and endothelial cells.
(Invited) Noninvasive Detection and Spectral Triangulation of Single-Walled Carbon Nanotubes In Vivo
Authors: Weisman R. Bruce , Lin Ching-Wei , Bachilo Sergei M. , Beckingham Kathleen M. , Yang Hailing , Bast Robert C.
Published: February 2020

For toxicology studies on carbon nanotubes or the development of nanotube-based diagnostic or therapeutic agents, it is necessary to monitor the presence of nanotubes inside organisms. Preferred monitoring methods are noninvasive and safe, and can be performed on the laboratory mice commonly used in preclinical research. To advance the in vivo optical detection of single-walled carbon nanotubes (SWCNTs), we have recently developed instrumentation and methodology called spectral triangulation. In this method the specimen is diffusely illuminated by a matrix of light-emitting diodes and the resulting short-wave infrared fluorescence from internal SWCNTs is collected by an optical fiber at or near the animal’s skin. The fluorescence is then transmitted through spectral filters to a cooled InGaAs photon counting detector sensitive to the emitted wavelengths. The high sensitivity of this system allows localized SWCNT deposits of ca. 10-8 g to be detected through 20 mm of tissue phantom. In addition, by systematically varying the position of the light collector and measuring emission intensities in two wavelength bands, we can deduce the 3D location of the SWCNT deposit by spectral triangulation computations. Here we report refinements to the method and performance tests with live mouse specimens. The current LED excitation matrix emits at a longer wavelength (near 736 nm) to give higher penetration and reduced SWIR autofluorescence. A new specimen holder gently squeezes the mouse against a thin fused silica window, allowing the light collection fiber to translate only in a plane to significantly reduce scan times. Results on sensitivity limits and 3D triangulation accuracy will be presented from tests in which SWCNTs in Matrigel are implanted into mouse ovaries to simulate an antibody-targeted diagnostic application.

References

C.-W.Lin, S. M. Bachilo, M. Vu, K. M. Beckingham, and R. B.Weisman, Spectral Triangulation: a 3D Method for Locating Single-Walled Carbon Nanotubes in vivo, Nanoscale 8, 10348-10357 (2016).

C.-W. Lin and R. B. Weisman, In vivo Detection of Single-Walled Carbon Nanotubes: Progress and Challenges, Nanomedicine 11, 2885-2888 (2016).
(Invited) Organelle-Specific Targeting and Localization of Single Wall Carbon Nanotubes
Authors: Dahl Kris Noel , Islam Mohammad F.
Published: February 2020

Subcellular interaction and targeting of nanomaterials is important both to determine toxicity and for potential subcellular therapies of medical nanotechnology. Our collaborative research groups have investigated the intracellular targeting of single wall carbon nanotubes (SWCNTs) to different organelles based on tube varying length and surface coatings. SWCNTs longer than 1 µm do not localize within cells to any appreciable amount except for professional phagosomes such as macrophages. Purified, well-dispersed SWCNTs near 150 nm can be delivered at extremely high levels to numerous cell types, primarily dependent on cell metabolism and SWCNT surface functionalization. We have found that SWCNTs can be readily non-covalently dispersed with different bioactive macromolecules including (but not limited to) PEG triblock PF127 and bovine serum albumin (BSA) protein. SWCNT-PF127 are membrane active, escape endosomes and localize to actin inside the cell wherein many are retained inside of cells. SWCNT-BSA localize with endoplasmic reticulum (ER) and lipid vesicles along the metabolic pathway within cells. SWCNTs-BSA are then lost from cells via exocytosis unless endosomes are disrupted inside cells. Unless specifically targeted, we find that SWCNTs do not localize to the nucleus or mitochondria of cells. Thus, long-term cellular vitality and genetic stability of cells does not appear to be altered with SWCNT exposure. Specifically, mitochondria structure and function are not altered with high levels of SWCNT treatment (either SWCNT-BSA or SWCNT-PF127) including ATP production or any other aspects of long-term cellular toxicity. Generally in these cellular studies, there are unique challenges in merging nanomaterials characterization with cellular science and engineering. Most imaging technologies of cellular structure and function requires optical microscopy including immunocytochemistry, expression of fluorescent-tagged proteins and assays with fluorescent readouts. However, SWCNTs are optically active and quench fluorescence intensity obscuring intensity-based signals, which limits imaging capabilities and alters accuracy and precision of cellular assays. We have utilized the optical activity of the SWCNT as a marker for colocalization by quantifying changes in fluorescence lifetime of the fluorophore within the Förster radius of the SWCNT. This and other complications of nano-cell interactions necessitates the need for numerous complementary techniques when assessing structural and functional association between SWCNTs and cellular organelles and compartments.
(Invited) Soft Conductors from Carbon Nanotubes
Authors: Pasquali Matteo
Published: February 2020

Since their infancy, carbon nanotubes (CNTs) were viewed as an exciting new material that combined superior transport properties with great mechanical strength and stiffness—a classical “hard material”. These expectations were based on single-molecule measurements; yet, translation to macroscopic materials proved arduous because CNT did not dissolve easily in liquids, while solvent-less assembly yielded largely disordered structures.

I will present an overview of the past fifteen years of research on assembling well-ordered macroscopic CNT materials, much of it conducted in close collaboration with Bob Hauge. From the perspective of soft matter, CNTs can be treated as hybrids of rodlike polymers and cylindrical colloids. CNTs dissolve spontaneously in acids, and form liquid crystals with intriguing morphology. Because dissolution is spontaneous, CNTs do not suffer mechanical or chemical damage and can reach high concentrations that enable material processing into fibers, thin films, tapes, and three-dimensional structures.

Intriguingly, these macroscopic CNT structures display mechanical and solid-state properties on par with the best metal and carbon fibers—even in the absence of covalent coupling between the CNTs, making them a viable lightweight, corrosion-resistant replacement for metals. Yet, the most surprising property—and perhaps the one that will prove most useful in future applications—was not predicted in the early days (and could not have been predicted based on single-CNT properties): macroscopic assemblies of CNTs display a “softness” that is completely uncharacteristic of highly conductive materials. They can be knotted, sewn with a common sewing machine, woven with a common loom, and still retain their properties—making them a great platform for electronic textiles and wearable devices. Moreover, these materials have intrinsic nanoscale porosity and display extremely low impedance in contact with biological tissue. This makes them a natural interface to the electrical function of the body, where they could be used as restorative patches for electrically damaged heart tissue as well as electrodes for stimulating and sensing the activity of the brain.
The Electrochemical Performance of Nitrogen-Containing Carbon Nanotubes As the Electrode Material of Supercapacitors
Authors: Li Xinping , Xu Guofeng , Deng Fuhai , Li Jianling
Published: February 2020

Electrochemical electric double layer capacitors (EDLC) known as supercapacitors are used for high power density, long cycle life and good reversibility of charge/discharge processes[1]. Recent years, many Schiff base transition metal composites acting as an electroactive electrode material deposited on carbon nanotubes(CNTs) have been researched[2]. However, the CNTs tend to be random orientation, twining round and cross linked. So it urgently need to be addressed. In this paper, a given mass of NH4BF4 was added to CNTs and the electrode was prepared by the homodispersion of the raw support material in N-methyl- 2-pyrrolidone (NMP) through sonicating. The slurry was coated on a Ti sheet with the coating mass of 0.3 mg. The electropolymerization of Ni(salen) on the resulting electrode was conducted in a closed three-electrode compartment cell adopted chronoamperometry method. The introduction of NH4BF4 to the CNTs with a specific percentage (5wt. %, 10wt. %, 15 wt. %), and the modified samples were named as NBF5, NBF10, NBF15 respectively and the CNTs without NH4BF4 were taken as a control group and named as NBF0. As the cyclic voltammetric data summarized in Table 1, the values of apparent surface coverage(Γ) and doping level(n) of NBF5, NBF10 and NBF15 didn't appear to be much different from those of NBF0. However, the specific capacitance varied a lot. It can be seen that Cm
of NBF15 is the most among the samples. Figure 1 depicts the GCD plots of the composite and CNTs at the current density of 1.0 mA cm-2. CNTs have symmetric change in the charge/discharge process which is the characteristic of high Coulombic efficiency. It is clear that the composites possess longer charge/discharge time than CNTs which indicating that poly[Ni(salen)] contributes the pseudo-capacitance derived from reversible redox switching between neutral and oxidative states on the basis of electric double-layer capacitance of MWCNTs. Because of the introduction of NBF, it became difficult for CNTs to twint together disorderly. And the morphylogy of the electrode support got homogeneous. NBF-containing carbon nanotube could provide basic sites, and consequently improved the deposition of polymer and enhance the performance of the electrode material.

Acknowledgement

This work is financially supported by the National Natural Science Foundation of China (No. 51372021).

References

[1] D. Kaufman, K.L. Hudson, R. Mcclamrock. Science. 343 (2014) 1210–1211.

[2] Y. Zhang, J. Li, F. Gao, F. Kang, X. Wang, F. Ye, J. Yang. Electrochim. Acta. 76 (2012) 1–7.

Figure 1
(Invited) Environmental Effects in Cryogenic Carbon Nanotube Spectroscopy
Authors: Högele Alexander
Published: February 2020

The photophysical properties of cryogenic carbon nanotubes are dominated by exciton localization. As exciton localization is commonly accompanied by exciton polarization, localized carbon nanotube excitons are particularly sensitive to electrostatic fluctuations in their immediate environment. We will discuss the realm of environmental effects observed in cryogenic spectroscopy of individual carbon nanotubes in different dielectric environments.
(Invited) Single Ion Adsorption on Individual Isolated Single Walled Carbon Nanotube Field Effect Transistors
Authors: Cronin Stephen B. , Bushmaker Adam
Published: February 2020

The detection of single ions has, for many years, been the domain of large devices such as the Geiger counter, and to date, there have been no studies investigating the effects of ions on materials and devices at the single-ion level, despite the widespread use of gaseous ions to modify material surface properties, for instance by corona discharge. Here, we report on single gaseous ion adsorption onto individual carbon nanotube field effect transistors, which, due to the severely restricted one-dimensional current path, experience discrete, quantized resistance increases of over two orders of magnitude [1]. Switching events were observed during exposure to lightly ionized nitrogen, helium, oxygen, argon and air. This is in contrast to single neutral atom adsorption detection techniques, which have shown only small, barely detectable responses. Only positive ions cause changes, by the mechanism of ion potential induced carrier depletion, which is supported by density functional and Landauer transport theory. Our observations reveal a new single-ion/CNT heterostructure with novel electronic properties, and demonstrate a powerful new system for studying ion adsorption dynamics at the single-ion level.

[1] Bushmaker, A. W. et al. Single-ion adsorption and switching in carbon nanotubes. Nature Communications, 7, 10475, DOI: 10.1038/ncomms10475 (2016).
Design of Metal Oxide Anode Materials for Lithium-Ion Batteries
Authors: Palmieri Alessandro , Ng Benjamin , Mustain William E.
Published: February 2020

Li-ion batteries (LIBs) have been the leading technology in the portable electronics market since their discovery by Sony in the 1990s. At the anode, graphite has remained ubiquitous for commercial Li-ion batteries since its discovery as a reversible intercalation material over 30 years ago, leading to a typical specific energy density of ca. 150 Wh/kg. However, due to both rising consumer demand for enhanced capabilities of portable electronics and the emerging application of Li-ion batteries to larger systems (such as electric vehicles and even grid-scale energy storage), it has become clear that existing cell components will not be sufficient. Therefore, it is important to develop new active materials and electrolytes that allow Li-ion battery energy and power density to be doubled in the near future.

One of the most promising classes of anode materials are conversion transition metal oxides (MOs). These MOs rely on chemical transformations with more than one electron transfer step to store and deliver energy, which results in theoretical capacities 2-3 times higher than graphite. In addition, they have a safer lithiation potential that eliminates the possibility for problematic lithium plating during charging. Lastly, MOs are naturally abundant and typically environmentally friendly. However, the use of metal oxides in their raw state has been limited by their low electronic conductivity – which promotes phase separation and large domain sizes from the metal and Li2O phases that form during charging. It is this nanoscale phenomena that limits MO cycle life to graphite compared to graphite [1]. To circumvent these challenges, our group has focused on methods that increase the intra-particle and inter-particle electronic conductivity of the anode electrode [2-4]. In this talk, we will discuss the efficacy of several approaches to improve conductivity and capacity retention in NiO, Co3O4 and MnO chemistries, including supporting the MOs onto advanced carbons, creating metal-metal oxide composites and transition metal doping. There will be a specific focus on material families that have been engineered, through fundamental scientific discoveries, to achieve stable anode electrodes over several hundred cycles. We will also discuss opportunities and challenges when pairing these MO anode materials with traditional cathodes in full cells.

References.

1. N. Spinner, L. Zhang, W. Mustain, Journal of Materials Chemistry A, 2 (2014) 16278.

2. N. Spinner, A. Palmieri, N. Beauregard, L. Zhang, J. Campanella and W. E. Mustain, Journal of Power Sources, 276 (2015) 46.

3. Y. Liu, A. Palmieri, J. He, Y. Meng, N. Beauregard, S.L. Suib and W.E. Mustain, Scientific Reports, 6 (2016) 25860.

4. A. Palmieri, R. Kashfi-Sadabad, S. Yazdani, M. Pettes, W. E. Mustain, Electrochimica Acta, 213 (2016) 620.
Towards Better Utilization Ratios of Active Materials in Redox Flow Batteries
Authors: Duan Wentao , Li Bin , Lu Dongping , Wei Xiaoliang , Nie Zimin , Murugesan Vijayakumar , Kizewski James , Hollas Aaron , Reed David , Sprenkle Vincent , Wang Wei
Published: February 2020

Redox flow batteries, as promising candidates for grid-scale energy storage, have recently attracted a great wealth of research interests. Capital costs, however, are still hindering large-scale commercialization of redox flow batteries, within which chemical cost plays an important role. To reduce chemical costs, the promotion of utilization ratios of active materials (chemical fuels) in current redox flow batteries is a possible solution, which could potentially further lower the cost of the whole system.

In this presentation, we report such efforts from our lab on two redox flow batteries: the all vanadium and zinc iodide systems. Through optimizations of electrolyte components and re-design of flow chemistry, utilization ratios of active materials, as well as specific volumetric capacities, are significantly enhanced in these systems.
Aqueous Organic Redox Flow Batteries (AORFBs) for Sustainable and Safe Renewable Energy Storage
Authors: Hu Bo , DeBruler Camden , Liu Tianbiao
Published: February 2020

The presentation will cover my group research efforts in developing high performance aqueous organic redox flow batteries (AORFBs) aiming for sustainable and economical large-scale energy storage from solar and wind. We have pioneered the development of novel AORFBs employing water-soluble redox active molecules including viologen, ferrocene, and TEMPO.[1-4] Particularly, the chemistry and battery performance of the FcNCl/MV AORFB will be discussed in detail,[1] where FcNCl is (ferrocenylmethyl)trimethylammonium chloride and MVis methyl viologen dichloride. Challenges and advances in developing AORFBs for practical applications will be discussed. How chemistry plays crucial roles in developing the new generations of redox flow batteries will be emphasized.

References: (1) Hu, B.; DeBruler C., Rhodes, Z.; Liu, T. L.*, J. Amer. Chem. Soc., 2017,139, 1207. (2) Liu, T.;* Wei, X.; Nie, Z.; Vince, S.; Wang, W. Adv. Energy Mat. 2016. (3) Filed US Patents covering applications of water soluble viologen, ferrocene derivatives, and TEMPO for RFBs (4) Group website: www.tianbiaoliu.org
(Invited) Transport Phenomena in Electrochemical Energy-Conversion Technologies
Authors: Weber Adam Z.
Published: February 2020

The issue of transport phenomena is omnipresent in various electrochemical energy-conversion technologies. There is a need to understand and optimize the various means for products and reactants, whether gas, liquid, or ions to get to and away from the reaction sites. Such transport often results in concentration polarization and ohmic effects in various electrochemical cells. Mathematical modeling and advanced diagnostics are ideally suited to elucidate and explore the impacts of transport phenomena on device performance.

In this talk, we will discuss current research questions and issues related to transport phenomena in various electrochemical energy-conversion technologies including solar fuel generators, polymer-electrolyte fuel cells, and redox flow batteries. These various technologies share very similar architectures of typically ion-conducting polymer membranes sandwiched between thin catalyst layers that are porous electrodes. Specific topics to be discussed include reactant gas transport to the local reaction site in vapor-fed solar-fuel generators, local oxygen transport in polymer-electrolyte fuel cells, and ion transport and selectivity in redox flow batteries.

Acknowledgement

This work was funded by the Department of Energy under contract number DE-AC02-05CH11231.