bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progress in Studying Mediator Supercapacitor
Authors: Zhou Xiangyang , Cai Jinshu , Wang Yuchen , Zhang Chen , Qiao Xiaoyao , Mansour Azzam 
Published: February 2020

When mediators (redox molecules) are mixed into an ion conducting polymers, the material will have a high ionic conductivity and electronic conductivity potentially providing a high storage capacity and charge/discharge rate. On the basis of our previous work of developing I2/NaI and K3Fe(CN)6/K4Fe(CN)6based supercapacitors, we studied the ionic conductivity, electronic conductivity, and capacity of the electrode materials as a function of concentration of mediators and temperature. A modified percolation model was proposed and used to describe the observations. In another line, we fabricated prototypes using commercially available materials.
The ionic and electronic conductivities were evaluated using a series of AC/DC measurements. The results indicate that for the electronic conductivity, there is a critical mediator concentration at which the conductivity steps up two orders of magnitude. For the ionic conductivity, the increase with mediator concentration is smooth. When the temperature decreases from 20°C to -20°C, the ionic conductivity decreases ~8 folds but is still greater than 10-3 S/cm. This demonstrates that the presence of mediators in the material helps maintain a high ionic conductivity at -20°C. Cyclic voltammetry and charge/discharge test results are correlating and consistent with the conductivity measurement results. A percolation model was created with consideration of motion of the mediators at a given temperature. The simulation results agree well with the experimental data. The theoretical analysis indicates that charge exchange between mediator molecules promotes ionic conductivity via causing instant imbalance of the local charge distributions. Finally, supercapacitor prototypes were fabricated using the electrode materials with PVDF/LTFS and a mediator. The specific energy was 25 Wh/kg at 0.2 kW/kg or 10 Wh/kg at 25 kW/kg after cycling 2000 times.
2-Dimensional Supercapacitor Wires to Overcome Intrinsic Low Energy Density
Authors: Park Jongseok , Nam Inho , Park Soomin , Bae Seongjun , Yoo Young Geun , Yi Jongheop 
Published: February 2020

Although a large number of reports on 2D flexible and stretchable energy storage devices have emerged within the past decade, 1D structure systems such as wires for higher flexibility, bio-compatibility and wearability have been desired for broader application of electronics. As a result of these requirements, wire-shaped devices among the cutting edge technologies in energy storage field are taking center stage for application to postmodern electronics and various fields such as fashion and culture. In view of mechanics, plane structures in 2D essentially have a unidirectional folding characteristics. On the other hand, wires with 1D structure have an omnidirectional serpentine structure in the other axes. In contrast to 2D planar formats, it is much easier for wire types to be integrated into more sophisticated structures such as woven textiles that can be used in our daily life.
Although wire systems have a large structural potential, some fundamental obstacles hinder the use of wire-type energy storage. Electrochemical performances of wires are still underneath those of 2D plane cells. Many researchers have made efforts to overcome these barriers of wire-type energy storage devices. Most of them suggests ways to shape electrodes into cylindrical wires and a choice of material to maximize the performance as high as possible. In this study, however, we did not stick to using superb materials or constructing a cylinder, but theoretically analysed the origin of undefeatable charge-storage property of 2D plane over 1D wire. Based on this analysis we verified that a difference between wire-type and conventional planar supercapacitors induced the fundamental limits of wire-type supercapacitors. This limit is termed “energy lag effect.” With these derived information, we have first proposed the simultaneous incorporation of favorable electrochemical performance of 2D system and high flexibility of 1D system into solely one device. To exclude the identified limits, we designed a supercapacitor thread in unique structure that completely differs from conventional wire-type energy storage systems. The supercapacitor thread was designed as a dual plane-helix structure and proved not to show energy lag effects, experimentally or analytically.
Solid Polymer Electrolytes: Material Design As Gel or Membranes for Battery Applications
Authors: Srour Hassan , Monnereau Cyrille , Bucher Christophe 
Published: February 2020

The development of polymer electrolytes has drawn the attention of many researchers in the last three decades as they find applications not only in lithium batteries but also, in other electrochemical devices such as super capacitors and electrochromic devices, etc. These polymer electrolytes have several advantages over their liquid counter parts. they are expected to replace flammable and leakage-prone organic solvent-based as electrolytes in future energy storage devices. In addition, these electrolytes have no internal shorting and non-combustible reaction products at the electrode surface existing in the liquid electrolytes [1-2].
In this communication, we will present a novel methodology, and straightforward conceptual approach for convenient preparation of gel-type polymers and membrane electrolytes [3] ( figure 1). We will demonstrate their morphologies and mechanical properties by rheological measurements of the gel under different strains and by XPs. Finally, we will illustrate the potential of the resulting gels as quasi-solid materials for energy storage applications through the study of different parameters such as: electrochemical stability, lithium diffusion and ionic conductivity properties,cycling test.
[1] Mecerreyes, D., Prog. Polym. Sci
36(12), 1629-1648 (2011).
[2] Yuan, J.; Mecerreyes, D.; Antonietti, M., Prog. Polym. Sci
38(7), 1009-1036 (2013).
[3] Srour, H.; Ratel, O.; Leocmach, M.; Adams, E. A.; Denis-Quanquin, S.; Appukuttan, V.; Taberlet, N.; Manneville, S.; Majesté, J.-C.; Carrot, C.; Andraud, C.; Monnereau, C., Macromol. Rapid Commun. 36 (1), 55-59 (2015)

Figure 1
Enhanced Conversion and Storage of Solar Energy Using an All-Vanadium Continuous Photoelectrochemical Flow Reactor
Authors: Wei Zi , Shen Yi , Liu Dong , Liu Fuqiang 
Published: February 2020

With a demonstrated high Faradaic efficiency of 95%, an all-vanadium (all-V) photoelectrochemical storage cell (PESC) has been deemed as a promising candidate for efficiently capturing and storing solar energy.(1, 2) In this work, we further enhanced photocurrent of the existing all-V PESC by 5X by utilizing forced convective transport of the reactants throughout the cell in a continuous flow reactor, such that diffusive transport is only required over a short length scale relative to the cell dimension. It has been found that the maximum solar storage performance of the all-V PESC device tends to be limited by ionic and reactant transport, since we already employed vanadium redox species with fast electrochemical kinetics. Zero-resistance ammetry (ZRA) and electrochemical impedance spectroscopy (EIS) were employed to study the photoelectrochemical response of this system during conversion and storage of solar energy under both illumination and dark. It was discovered that introduction of flow during photoelectrochemical conversion greatly enhanced the photocurrent by 5 times comparing to the static condition (Fig. 1). Furthermore, EIS results indicated that both charge transfer resistance and interfacial capacitance were greatly reduced with convective flow of vanadium redox. On the other hand, variation of flow rate, if above a certain threshold, didn’t have a noticeable impact on the photocurrent under the range we explored. To better understand the photoelectrochemical behavior of the system, a CFD-based numerical simulation was carried out to understand the influence of flow rate on the photocharging process as well as the reaction limiting factors during solar energy storage.
Reference:
1. D. Liu, W. Zi, S. D. Sajjad, C. Hsu, Y. Shen, M. Wei and F. Liu, ACS Catalysis, 5, 2632 (2015).
2. Z. Wei, D. Liu, C. Hsu and F. Liu, Electrochemistry Communications (2014).

Figure 1
Batteries Under the Microscope: 3D and 4D Image-Based Characterization
Authors: Gelb Jeff , Finegan Donal , Brett Daniel J.L , Shearing Paul R. 
Published: February 2020

In recent years, there has been a rapid growth in the development and application of Li-ion batteries in many aspects of daily life. From portable electronic devices to electric vehicles, global reliance on portable energy storage solutions is projected to continue growing throughout the next decade. To facilitate adoption of the Li-ion battery technologies, much of the current research is focused on improving electrode chemistries and developing novel cells, capable of lasting for longer time periods to reduce the need for frequent recharging. In spite of these developments, however, there exists little in the literature to show exactly how battery materials respond to charge cycling and why batteries ultimately fail.
Within the context of the present study, multi-length scale X-ray microscopy (XRM) was used to image a commercial 18650 Li-ion battery from the 20 µm length scale to the 0.1 µm length scale in 3D, to identify the relevant information observable at each resolution level. Correlative light- and scanning-electron microscopies were employed to provide additional information about the structure of the electrodes and to provide resolution down to the nanometer scale. The results revealed a complex, multi-scale structure to the battery electrodes, ranging from bulk defects (at the largest length scale) to porosity & tortuosity (at the hundred nanometer length scale) and sub-particle defects (on the 100 to sub-100 nm length scale).
One of the key advantages offered by X-ray imaging is the non-destructive nature of the 3D image-based characterization. With this in mind, the second part of the present study focused on utilizing this feature to perform a 3D imaging study before and after aging the battery, in a “4D” experimental design. Another sample from the same manufacturer was used for this study and imaged with 2 µm resolution in order to capture the finer cracks forming as a function of operation. The battery was imaged in its pristine state, charge cycled 100 times, and then the same specimen was imaged again using the same imaging conditions. From the 3D volumetric results, several cracks were observed to form on the outer side of the roll, following the capacity fade observed in the testing apparatus. This result has suggested the significance of microstructure-based degradation and pointed toward the importance of using image-based characterizations in Li-ion battery operational and lifetime studies.
In this presentation, we will present the study outlined here, both in terms of the 3D and the 4D investigations of the commercial 18650 Li-ion battery cells. The experimental design will be discussed in detail, including the imaging apparatus and the correlative imaging setup. Furthermore, the 3D imaging results will be shown alongside a discussion of the relevant geometric parameters at each length scale, and the results of the 4D investigation will be presented showing the defect formation as a functio
A New and Fast Depth Profile Analysis for Li Ion Battery Electrode - Elemental Composition of Conductive and Non Conductive Coatings Including Li, O, H, C
Authors: Savadkouei Kayvon , Hunault Philippe , Chapon Patrick , Gaiaschi Sofia 
Published: February 2020

Rf GD-OES (Radio Frequency Glow Discharge - Optical Emission Spectroscopy) is a technique which can provide a Depth Profile Elemental Composition of coatings and thin films. In the case of the Li ion Battery Electrodes, it is possible to get the variation of all the elements in the organic coating and underneath layers until the substrate. Almost all the elements can be analyzed at the ppm level including Li, O, H, C, Cl, F, N...
Conductive and non-conductive materials can be analyzed. Due to the very fast sputtering rate, only few minutes would be necessary to analyzed Electrodes. This technique is complementary to SIMS, XPS... but much more affordable. Special sample holder for samples which are Air Sensitive (containing Li) have also been designed to avoid any contact with air. After a brief explanation of the theory, the presentation will focus on Li Ion Battery Electrode applications, but other applications linked to the Energy Storage (as corrosion, defect,...) will also be presented.
Nb4N5/Nb2O5/r-GO Composites As Anode Materials for High Power Lithium Ion Batteries
Authors: Yan Yan , Lai Chun-Han , Dunn Bruce , Tolbert Sarah H 
Published: February 2020

Lithium-ion batteries have been extensively investigated for a range of portable electronic devices, but a major downside to current technology is the slow charging speeds. A potential solution is to utilize pseudocapacitve materials, in which the diffusion length for lithium ions is short. For example, Nb2O5 is a promising anode material with almost no kinetics limitations for solid-state Li+ diffusion due to the facile two-dimensional Li+ transport pathways within the structure. However, it is also a large bandgap semiconductor, with a low bulk electrical conducitivity of ~3.4 x 10-5 S cm-1at 300 K. The low electronic conductivity hinders its high-rate performance, especially for thick electrodes with high mass loadings.
Numerous composite structures have been explored to improve the sluggish mobility of electrons in Nb2O5, such as blending with carbon nanotube, graphene composites, and carbon coating. Here we report an Nb4N5/Nb2O5/reduced graphene oxide (rGO) composite structure with improved kinetics prepared via partial nitridation of Nb2O5. Nb4N5 shows excellent metallic conductivity of 2000 S cm-1, which facilitates the interparticle electron conduction pathway in combination with the conductive graphene scaffold. Very high capacity retention at high charging/discharging speed is achieved in these materials, though the high power density comes at some cost of the capacity because the nitride is electrochemically inactive. One important advantage of the niobium oxide/nitride system, compared to pure Nb2O5/carbon composites is improved interface between the electrochemically active material and the conductive coating, since Nb2O5 can transform to Nb4N5 with almost no structural change. The composite also has a high volumetric capacity, since carbon additive is not needed in slurry electrodes. We believe metal oxide/metal nitride composites could provide a new design for high power electrode materials.
Catalyst-Selective Direct Liquid Fuel Cells without the Need for an Ion-Exchange Membrane to Separate the Anode Fuel and the Cathode Oxidant
Authors: Yu Xingwen , Pascual Emilio J. , Wauson Joshua C. , Manthiram Arumugam 
Published: February 2020

Among the several types of direct liquid fuel cells (DLFCs) under development with various liquid fuels, the direct methanol fuel cell (DMFC) is in the forefront. However, this technology is currently in a difficult situation. The challenges of the relatively well-developed DMFCs with the proton-exchange membrane (PEM) include (1) the high-cost of Nafion membrane, (2) the sluggish kinetics of electrode reactions (rely on the high-loading Pt-based catalysts), and (3) the crossover of the methanol fuel through the PEM.1
,
2 According to the above issues, two approaches have recently been proposed and attempted, which can individually overcome the challenges of (1) – (3). Operation of the DMFCs under alkaline condition is able to enhance the kinetics of the electrode reactions.3 Operation of the DMFCs under a laminar-flow principle can avoid the use of the expensive PEMs and without the fuel crossover concerns. However, each of these two approaches brings new unexpected problems. Operation of the DMFCs under alkaline conditions needs an OH--exchange membrane which is currently not quite available. The laminar-flow membraneless DMFCs can only be built to a miniature scale, which limits their practical applications.4

Herein we present a membraneless alkaline DLFC approach developed under a catalyst-selective philosophy. By employing a non-platinum, highly selective cathode catalyst (MnNiCoO4/N-MWCNT, MnNiCoO4 nano-particles on a nitrogen-doped multi-wall carbon nanotube)5 with favorable activity for the oxygen reduction reaction (ORR) but without any activity for the fuel oxidation reaction (FOR), membraneless-operation of the DLFCs is turned into reality without any concerns about the fuel crossover from the anode to the cathode.
The first example of this presentation is an alkaline membraneless DMFC system with methanol as the anode fuel. The second example is an alkaline direct formate fuel cell (DFFC) with aqueous potassium formate solution as fuel. In comparison to the CH3OH-favorite catalyst PtRt/C and the HCOOK-favorite catalyst Pd/C, the MnNiCoO4/N-MWCNT does not show activities for oxidation of either CH3OH or HCOOK. The fuel cell performances of the membraneless DMFC (PtRu/C ǁ CH3OH/KOH ǁ MnNiCoO4/N-MWCNT) and the membraneless DFFC (Pd/C ǁ HCOOK/KOH ǁ MnNiCoO4/N-MWCNT) are superior to those of the traditional membrane-based DMFCs.

References

1. X. W. Yu and S. Y. Ye, J Power Sources, 2007, 172, 133-144.
2. T. R. Ralph and M. P. Hogarth, Platin Met Rev, 2002, 46, 117-135.
3. J. R. Varcoe and R. C. T. Slade, Fuel Cells, 2005, 5, 187-200.
4. S. A. M. Shaegh, N. T. Nguyen and S. H. Chan, Int J Hydrogen Energ, 2011, 36, 5675-5694.
5. X. W. Yu and A. Manthiram, Catal Sci Technol, 2015, 5, 2072-2075.
(Invited) Synthesis and Photophysical Properties of Porphyrin-Fullerene Linked Dyads with a Oligo-p-Xylene Bridge
Authors: Imahori Hiroshi 
Published: February 2020

Photoinduced electron transfer (ET) is one of the most fundamental processes in physics, chemistry, and biology. In the reaction center of natural photosynthesis, photoinduced ET generates a long-lived charge separation (CS) state with ~100% efficiency, leading to light-to-chemical energy conversion. In contrast, photoinduced CS at the interfaces of organic photovoltaic cells and dye-sensitized solar cells generates electron-hole pair, eventually achieving light-to-electricity conversion. However, the interfaces of semiconductor/dye and donor/acceptor (D/A) in artificial photosynthesis and organic photovoltaic cells often suffer from the partial or even large loss of the CS state at the early stage, which has still been controversial and not unveiled owing to inevitable inhomogeneous spatial distribution of D-A components.
In this context D-A linked systems have generated remarkable interest for the last few decades. The D-A covalent linkage can eliminate complex factors arising from diffusion in solutions and assess the photoinduced ET properties precisely with the help of homogenous spatial distribution of the D-A components. So far these systems have provided fundamental information on photoinduced ET. Impact of various ET parameters, i.e., driving force, electronic coupling, reorganization energy, and temperature, on ET rate has been evaluated by using elaborated D-A linked molecules. In particular, a well-defined D-A linked molecule with a rigid bridge has allowed us to shed light on photoinduced ET more accurately. Here we show unprecedented dependence of the final CS efficiency on D-A interaction (i.e., electronic coupling) that can be changed systematically in the D-A linked models with a one-dimensional (1D) nonconjugated bridge. We have thoroughly examined the photoinduced ET properties by using femtosecond to microsecond time-resolved transient absorption (TRTA) and electron paramagnetic resonance (TREPR) spectroscopies.
References
[1] H. Imahori and Y. Sakata, Adv. Mater. (Review Article), 9, 537-546 (1997).
[2] H. Imahori and Y. Sakata, Eur. J. Org. Chem. (Microreview), 1999, 2445-2457.
[3] H. Imahori, Y. Mori, and Y. Matano, J. Photochem. Photobiol., C: Photochem. Rev., 4, 51-83 (2003).
[4] H. Imahori, Org. Biomol. Chem. (Perspective), 2, 1425-1433 (2004).
[5] H. Imahori, J. Phys. Chem. B (Feature Article), 108, 6130-6143 (2004).
[6] H. Imahori and S. Fukuzumi, Adv. Funct. Mater. (Feature Article), 14, 525-536 (2004).
[7] H. Imahori, Bull. Chem. Soc. Jpn. (Award Accounts), 80, 621-636 (2007).
[8] T. Umeyama and H. Imahori, J. Phys. Chem. C (Feature Article), 117, 3195-3209 (2013).
(Invited) Switchable Electron Transfer Reactivity in Phthalocyanine Sc3n@C80 Supramolecular Ensembles
Authors: Trukhina Olga , Torres Tomas , Bottari Giovanni , Guldi Dirk M. , Echegoyen Luis , Rudolf Marc , Akasaka Takeshi , Almeida Veronica , Muñoz Nicolas 
Published: February 2020

Phthalocyanines (Pcs) are planar, two-dimensional aromatic pophyrinoids which possess outstanding structural, optical and electrical properties as well as stability that render them perfect building blocks for the incorporation into multifunctional materials. Similarly, Ih
-Sc3N@C80 fullerene – the most abundant member of the fullerenes family after C60 and C70 – in addition to have excellent electron-accepting properties, provides conditions for an extra stabilization of charge-separated states due to the presence of the internal Sc3N species. This makes Ih
-Sc3N@C80 an ideal molecular partner for photo- and electroactive molecular systems such as Pcs.
Although several reports have appeared on the preparation of covalent Sc3N@Ih-C80 ensembles, there is no use of Ih
-Sc3N@C80 for the preparation of non-covalent assemblies. In this context, plenty of supramolecular systems arranged via coordination interactions have been successfully demonstrated for Pc-C60 supramolecular dimers and trimers. Low accessability of non-covalent supramolecular systems with Ih
-Sc3N@C80 is mainly caused by the more sophisticated synthesis and purification of the corresponding fullerene derivatives.
Herein, we report a novel example of donor-acceptor Pc/Ih
-Sc3N@C80 supramolecular dimers assembled via metal-ligand coordination interactions between Zn(II)Pcs and pyridil-substituted Ih
-Sc3N@C80 or C60 fullerene. Photophysical (ground- and excited state) and electrochemical studies on these ensembles showed that depending on the electron-donor or electron-acceptor character of the ZnPcs, a switchable electron transfer reactivity occurs in the case of the Ih
-Sc3N@C80 supramolecular systems, revealing the ability for this endohedral metallofullerene to behave either as electron donor or electron acceptor unit.
Cancer Hyperthermia Studies: On the Aqueous Structure and Radiofrequency-Induced Heating Properties of a Water-Soluble [60]Fullerene
Authors: Mackeyev Yuri , Muto Atsushi , Cheney Matthew , Serda Rita , Curley Steven A. , Wilson Lon J. 
Published: February 2020

The symmetrical, malonodiserinolamide hexa-substituted [60]fullerene, C60-ser, is a key water-soluble C60 derivative of interest for the treatment of cancer by radiofrequency(RF)-induced hyperthermia due to its biocompatibility, neutral charge, lipophilicity, and ability to cross restrictive biological membranes. In aqueous solution C60-ser, which is surrounded by 24 hydroxyl groups, maintains relatively stable layers of closely-bound water molecules (hydration sphere), forms highly dynamic aggregates, sized between 100-400 nm in diameter, which exist in equilibrium with individual, hydrated C60-ser molecules. Our recent observations indicate that these dynamic C60-ser aggregates are built up of a single layer of C60-ser molecules, with water locked inside a hollow core structure. Using a thermal imaging camera, aqueous C60-ser solutions have been shown to produce heat when irradiated with an 13.56 MHz RF field (900W) in a concentration-dependent manner with a heating rate of up to 1.0 °C/sec at 10 mg/ml. This result establishes that C60-ser is a neutrally-charged, key [60]fullerene-based nanoparticle, that might be used for the treatment of cancer by RFH-induced hyperthermia.
We acknowledge Kanzius Foundation and Welch Foundation Grant C-0627 for financial support.

Figure 1