bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of All-Solid-State Lithium Secondary Batteries Using Garnet Solid Electrolyte Layer
Authors: Shishihara Daisuke , Takeuchi Yuki , Hikosaka Hideaki , Mizutani Hidetoshi
Published: February 2020

Lithium ion secondary batteries have been used as power sources of various devices. The electrolyte of the lithium ion battery is needed to have high lithium ionic conductivity and wide electric potential window. In addition, it is favored to be nonflammable to enhance the safety of batteries. The oxide solid electrolyte is generally nonflammable, but the most oxide electrolyte has narrower potential window and lower ionic conductivity. In late years lithium garnet type oxide solid electrolyte (e.g. Li7La3Zr2O12[1]) is gaining attention due to have high Li+ ionic conductivity and electrochemical stability from 0 to 5V vs. Li/Li+. The development of the all-solid-state batteries using this garnet type electrolyte has been carried out, but there are various issues. The main issue of the all-solid-state batteries using oxide electrolyte is high internal resistance of electrodes, which originates from a poor contact not only between electrolyte particle and active material particle, but also among electrolyte particles.

We investigated all-solid-state lithium batteries using lithium oxide solid electrolyte ceramics layer (Li1.5Al0.5Ge1.5(PO4)3 or Li7La3Zr2O12). The internal resistance of electrodes was reduced by interposing sulfide solid electrolyte (Li2S-P2S5) between the oxide electrolyte layer and the active material (e.g. Sulfur or LiCoO2) (Figure 1). The cathode structure enabled the batteries to work at room temperature [2-4]. In this study, we have developed the garnet type lithium solid electrolyte which has higher ionic conductivity above 1.0 x 10-3 Scm-1at 25°C. The performance of the all-solid-state batteries, using the garnet electrolyte and the sulfide electrolyte which is interposed between the oxide electrolyte layer and the active material, will be presented.　　　　　　　　　　

References

[1] R.Murugan, V.Thangadurai, and W.Weppner, Angew. Chem. Int. Ed., 2007, 46, 7778

[2] D. Shishihara, 24th Fall meeting of the ceramic society of Japan,2J01(2011)

[3] D. Shishihara, 25th Fall meeting of the ceramic society of Japan,3A05(2012)

[4] D. Shishihara, 54th Battery symposium in Japan,2E25(2013)

Figure 1
Elemental Sulfur Mediated Facile Synthesis of a Colvalent Triazine Framework for High Performance Lithium-Sulfur Batteries
Authors: Hwang Tae Hoon , Talapaneni Siddulu Naidu , Coskun Ali , Choi Jang Wook
Published: February 2020

Sulfur is one of the most abundant elements and more than 70 million tons of elemental sulfur is annually produced as a by-product of the hydrodesulfurization process in the petroleum refining industry. This mostly involuntary production of sulfur, however, creates a significant global supply surplus. Therefore, the development of highly functional sulfur-rich polymers that are synthesized via direct utilization of elemental sulfur can be a useful direction in recycling the abundant sulfur to high value outcomes. Rechargeable lithium–sulfur (Li-S) batteries have received significant attention in recent years as one of such opportunities owing to their high theoretical gravimetric capacity and energy density of 1,675 mAh g-1 and 2,567 Wh kg-1, respectively. However, despite almost 30 years of development, Li-S batteries are still at the research stage, because of insufficient cycle life mainly due to the fatal redox shuttling process originating from the dissolution of the intermediate lithium polysulfide species in most of operating organic electrolytes during charge/discharge process.

 Herein, we report, for the first time, sulfur-medidated synthesis of CTF-1 (S-CTF-1) using 1,4-dicyanobenzene and elemental sulfur without any catalysts or solvents. The formation of CTF engages in-situ vulcanization with elemental sulfur, enabling both covalent attachment of sulfur and its homogeneous distribution within the pores. S-CTF-1 was found to have a high sulfur content of 62 wt% along with a well-shaped bipyramidal morphology that has been achieved without using any external template. We have also examined electrochemical performance of S-CTF-1 as a sulfur-cathode material in Li-S batteries. S-CTF-1 exhibited robust cycling performance for 300 cycles with 85.8% capacity retention along with the highest initial Coulombic efficiency (ICE) reported to date: 94.4% at 0.05C (25 mA g-1). Our results demonstrate the promising aspect of microporous polymers as active supports for sulfur, thus it is expected to motivate further research in this area. In a broader perspective, direct utilization of elemental sulfur in the synthesis of covalent triazine frameworks can open up new high-value applications, such as advanced electrode materials for energy storage and conversion.
Magnesium/Sulfur Rechargeable Batteries Using Liquid Mg Polysulfides
Authors: Vinayan Bhaghavathi Parambath , Cambaz Musa Ali , Zhao-Karger Zhirong , Fichtner Maximilian
Published: February 2020

Rechargeable magnesium (Mg) batteries are a sustainable option for electrochemical energy storage of renewable energy due to the inherent merits associated with Mg such as natural abundance, operational safety and high theoretical volumetric capacity (3,832 mAh cm-3), with a reduction potential of − 2.356 V versus normal hydrogen electrode (NHE).1 Among different types of cathode materials, the combination of Mg with a sulfur cathode and a non-nucleophilic electrolyte is very promising due to its large theoretical energy density of about 3200 Wh l−1, based on a two-electron conversion reaction expressed as, Mg2+ + S + 2e − ↔ MgS, which is beyond that of a Li/S battery (2800 Wh l-1). In addition, these battery systems are reversible and using low cost materials. Compared to the progress made on Li/S batteries, the Mg/S battery is still in a very early stage of research and development due to number of reasons such as low kinetics of Mg, lack of suitable electrolytes, polysulfide dissolution, insulating nature of sulfur, capacity fading etc.

Herein, we demonstrate a reversible Mg dissolved polysulfide cell using reduced graphene oxide (rGO) as the cathode host matrix and a non-nucleophilic Mg electrolyte in tetraglyme solution as the electrolyte. The electrolyte was prepared by mixing a non-nucleophilic base of magnesium-bis(hexamethyldisilazide) [(HMDS)2Mg] with the Lewis acid, AlCl3 (1:2 molar ratio) and dissolving the reaction product in a tetraglyme (C10H22O5) ethereal solvent . The liquid Mg polysulfides cell delivers better reversible capacity (~750 mAh g-1, Figure. 1) and cyclability as compared to previous Mg/S cell reports. The high surface area, porous structure and presence of oxygen functional groups over rGO give simultaneous physical and chemical adsorption of Mg polysulfides with the host matrix. Further, the working mechanism of liquid Mg polysulfides within Mg/S cell is investigated by Raman spectroscopy.

References

[1] H. S. Kim, T. S. Arthur, G. D. Allred, J. Zajicek, J. G. Newman, A. E. Rodnyansky, A. G. Oliver, W. C. Boggess and J. Muldoon, Nat. Commun., 2011, 2, 427.

[2] B. P. Vinayan, Z. Zhao-Karger, T. Diemant, V. S. K. Chakravadhanula, N. I. Schwarzburger, M. A. Cambaz, R. J. Behm, C. Kubel and M. Fichtner, Nanoscale, 2016, DOI: 10.1039/C5NR04383B.

Figure 1
Structural View of Li Ion and Electron Correlation in Li2FeSiO4 Cathode
Authors: Lu Xia , Chiu Hsien-Chieh , Arthur Zachary , Wei Huijing , Zhou Jigang , Wang Jian , Chen Ning , Jiang De-Tong , Zaghib Karim , Demopoulos George P.
Published: February 2020

Orthosilicates, Li2

M
SiO4, where
M

= Fe, Mn, Co, Ni, are characterized by a theoretical specific capacity that is twice that of LiFePO4, namely 340 vs. 170 mAh/g. In this presentation, we have probed the structural evolution and charge compensation of Li2FeSiO4 cathode using both in-situ/postmortem synchrotron XRD/XANES and first-principle calculations1-3. The results demonstrate that the formation of Li-Fe antisite defects play a key role in destabilizing the Li2FeSiO4 structure and “catalyzing” the monoclinic-to-orthorhombic transition. Then the charge compensation for the first Li extraction does not come solely from the ferrous to ferric conversion due to the strong electron correlation of Fe 3d orbitals, but interestingly from prominent participation of lattice oxygen as well that appears to destabilize the cycled structure. Using scanning transmission X-ray microscopy, it is revealed that the electrochemical lithiation/delithiation of Li2FeSiO4 electrode does not proceed uniformly but it exhibits an unusual solid solution pattern4 with the stored Li content varying locally possibly arising from a combination of inherent LFS material and electrode properties like poor conductivities, variable particle size/distribution and extent of electrolyte penetration. All these findings should have a thought-provoking influence on the study of the material itself and the broader Li-ion battery research community as well.

References

1.         Lu, X.; Wei, H. J.; Chiu, H. C.; Gauvin, R.; Hovington, P.; Guerfi, A.; Zaghib, K.; Demopoulos, G. P. Rate-dependent phase transitions in Li2FeSiO4 cathode nanocrystals. Sci Rep-Uk 2015, 5, 8599.

2.         Arthur, Z.; Chiu, H.-C.; Lu, X.; Chen, N.; Emond, V.; Zaghib, K.; Jiang, D.-T.; Demopoulos, G. P. Spontaneous reaction between uncharged lithium iron silicate cathode and LiPF6-based electrolyte Chem Commun 2015, accpeted, DOI: 10.1039/C5CC07197F.

3.         Lu, X.; Chiu, H.-C.; Bevan, H. K.; Jiang, D.-T.; Zaghib, K.; Demopoulos, P. G. Density functional theory insight into the structure stability and Li diffusion properties of monoclinic and orthorhombic Li2FeSiO4 cathodes. J Power Sources 2015, In revision.

4.         Lu, X.; Chiu, H.-C.; Arthur, Z.; Zhou, J. G.; Wang, J.; Chen, N.; Jiang, D.-T.; Zaghib, K.; Demopoulos, G. P. Quasi-equilibrium Li storage in metastable Li2FeSiO4 cathode. 2015, Under review.
Li4SnS4: Simulations of Its Structure and Electrolyte Properties
Authors: Holzwarth Natalie A. W.
Published: February 2020

Recent literature  [1,2,3,4] reports the use of Li4SnS4 and its alloys as a relatively stable solid electrolyte for use in all-solid-state Li batteries. This poster presents results of first-principles simulations of the ideal crystalline structures and of defects associated with Li ion migration in this material.    The simulations find that the lowest energy

structure of the idealized crystal is consistent with the structure determined by MacNeil et at. [2] from samples synthesized at high temperature (750 deg C). The simulations also find  a slightly higher energy structure which is consistent with the structure determined by  Kaib et al. [1] from samples prepared at lower temperature (320 deg C), processed from solution. Simulations of the Li ion migration properties of the two structures are compared.

Acknowledgements

This work was supported by NSF grant DMR-1507942 and by the Wake Forest University DEAC Computer Cluster.  Joseph MacNeil and Jennifer Aitken  contributed additional information about the experimental details.

[1]Thomas Kaib, Sima Haddadpour, Mauel Kapitein, Philipp Bron, Cornelia Schroeder, Hellmut Eckert, Bernard Roling, and Stefanie Dehenen, Chemistry of Materials, 24, 2211-2219 (2012)

[2]Joseph H. MacNeil, Danielle M. Massi, Jian-Han Zhang, Kimberly A. Rosmus, Carl D. Brunetta, Taylor A. Gentile, and Jennifer A. Aitken, Journal of Alloys and Compounds, 586, 736-744 (2014)

[3] Gayatri Sahu, Zhan Lin, Juchuan Li, Zencai Liu, Nancy Dudney, and Chengdu Liang, Energy & Environmental Science, 7, 1053-1058 (2014)

[4] Kern Ho Park, Dae Yang Oh, Young Eun Choi, Young Jin Nam, Lili Han, Ju-Young Kim, Huolin Xin, Feng Lin, Seung M. Oh, and Yoon Seok Jung, Advanced Materials,  DOI: 10.1002/adma.201505008
A Bi-Functional Organic Redox Catalyst for Rechargeable Lithium-Oxygen Batteries with Enhanced Performances
Authors: Zhang Jinqiang , Sun Bing , Xie Xiuqiang , Zhao Yufei , Wang Guoxiu
Published: February 2020

The Li-O2 battery provides the highest energy density among all rechargeable battery systems. To date, the large over-potentials during the oxygen reduction reaction and oxygen evolution reaction lead to low round-trip efficiency and short cycle life. Herein, we report a Li-O2 battery with outstanding performance. Application of a bi-functional organic catalyst, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA), significantly lowered the charge potential to 3.73 V and increased the discharge potential to 2.75 V. PTMA facilitates both efficient formation and oxidation of Li2O2 through its n- and p-doping ability coupled with superior catalytic activity. Furthermore, PTMA effectively coats the surface of the carbon electrodes, which suppresses side-reactions between carbon and the electrolyte leading to enhanced lifetimes.

Figure 1
Free-Standing Nitrogen-Rich Carbonization Polypyrrole Films As Advanced Anode for Lithium-Ion Batteries
Authors: Yuan Tao , Zhang Weimin , He Yu-Shi , Zheng Shiyou , Ma Zi-Feng
Published: February 2020

Recently, for the pursue of high energy density of Li-ion battery system and more lightweight and flexible battery for potential applications in flexible electronic devices such as wearable devices, artificial electronic skins, and distributed sensors, an extensive research effort is underway to produce soft free-standing electrode-active materials without binder and conductive agent for such bendable batteries.[1-3]

We propose here an N-rich pure carbon film synthesized by calcining vapour phase polymerized polypyrrole (PPy) film as an anode for Li-ion battery.[4] The PPy precursor film was synthesized via a simple vapor phase polymerization (VPP) bottom-up assembly method using Fe(III) tosylate oxidant (Figure 1). The obtained PPy film shows smooth surface and continuously cross-linked structure. After carbonized at high temperature at inert atmosphere, a continuously cross-linked carbon film doped with nitrogen can be formed. The carbonization process of PPy film precursor was result in large numbers of uniform mesopores in N-C film, which is expected to provide very regular pore channels for Li+ charge transfer and storage. The as-derived free-standing nitrogen-containing carbon film anode exhibits excellent electrochemical performance, especially, at high charge/discharge rate for lithium-ion batteries. The reversible capacities are 908.4, 825.7, 664.0, 531.6, 415.5 and 325.9 mAh g-1at 1C, 2C, 5C, 10C, 20C and 40C, respectively. The N-C film anode also shows excellent cyclability with high capacity. After 800 cycles, the reversible capacity retains 91.6% of the initial stage. The coulomb efficiency is close to 100%. Such free-standing flexible N-C film anode can be straightforwardly used to fabricate the lithium-ion batteries which are required to deliver high energy and power.

Acknowledgements:

We are grateful for financial support for this work from the National Basic Research Program of China (2014CB239700), the Natural Science Foundation of China (21336003, 21403139, 51472161, 51472160), the Shanghai Pujiang Program (No. 14PJ1407100) and the Science and Technology Commission of Shanghai Municipality (14DZ2250800, 15JC1490800, 12JC1406900, 14520721700). We acknowledge the support of the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning (TP2014048) and the Hujiang Foundation of China (B14006).

References:

[1] S. Zheng, Y. Chen, Y. Xu, F. Yi, Y. Zhu, Y. Liu, J. Yang, C. Wang, ACS nano, 10995-11003, 7 (2013).

[2] Y. Xu, Q. Liu, Y. Zhu, Y. Liu, A. Langrock, M.R. Zachariah, C. Wang, Nano lett., 470-474, 13 (2013).

[3] T. Yuan, B. Zhao, R. Cai, Y. Zhou, Z. Shao,
J. Mater. Chem.,
15041-15048, 21 (2011).

[4] T. Yuan, Y-S. He, W. Zhang, Z-F. Ma, Chem. Commun., 112-115, 52 (2016).

Figure 1
Biomass-Derived Carbonaceous Cathodes for Sustainable Lithium-Ion Storage
Authors: Liu Tianyuan , Lee Seung Woo
Published: February 2020

Biomass derived carbonaceous materials have been widely used as active electrode materials for electrochemical double layer capacitors (EDLCs) or hybrid capacitors. However, redox-active properties of these carbonaceous materials have not been explored. Here, for the first time, we demonstrated that carbonaceous materials from earth-abundant glucose via a hydrothermal carbonization (HTC) process have redox-active properties with lithium ions. Morphologies of the carbon materials can be controlled from spheres to sheets by using graphene oxide as a template. When used as cathodes in lithium ion cells, both the carbon spheres and sheets showed high redox potentials in the voltage range of 2.2 - 3.7 V vs. Li. Freestanding, flexible composite electrodes consisting of the hydrothermal carbon materials and few-walled carbon nanotubes delivered high specific capacities up to ~155 mAh/gelectrode for carbon spheres and ~176 mAh/gelectrode for carbon sheets, respectively. These carbon materials exhibited no obvious capacity fade up to 10,000 cycles, proposing to be promising cathodes for lithium-ion batteries or capacitors. The simple, scalable HTC process converting earth-abundant biomass source into high performance cathode materials enables the development of high-performance lithium-ion storage systems, which can provide a sustainable solution towards clean and renewable energy storage.
Role of the Transition Metal in Intermetallic Anodes
Authors: Vaughey John T.
Published: February 2020

Intermetallic anodes are a small but important subclass of lithium-ion battery anode materials.  In general materials in this class represent a compromise in terms of capacity and voltage compared to commercial materials but also tend to be crystallographically denser and have more stable cycling profiles.  Common examples include Cu2Sb, Cu6Sn5, and MnP [1-5].  They operate by inserting and storing lithium at low voltages using a variety of mechanisms that combine aspects of the main storage mechanisms. Intercalation anodes (e.g. graphite) insert lithium into existing crystallographic vacancies, conversion anodes store lithium in binary compounds formed by a disproportionation reaction, and Zintl phases react with lithium to form distinct crystallographic phases that undergo large bonding and volume changes as a function of lithium content [6].  In this presentation, a variety of intermetallic anodes will be assessed to better understand the role of the transition metal in allowing these materials to utilize multiple mechanisms to store lithium.  Knowledge gained from this analysis will be used to predict and better understand new high density anode materials.

[1] A. N. Jansen, J. A. Clevenger, A. M. Baebler, J. T. Vaughey J. Alloys Compounds
509 4457–4461 (2011)

[2] Keith D. Kepler, John T. Vaughey, M. M. Thackeray Electrochem. Sol State Lett., 2 307-309 (1999).

[3] Seung-Wan Song, R. P. Reade, E. J. Cairns, J. T. Vaughey, M. M. Thackeray,  K. A. Striebel  J. Electrochemical Soc., 151 (2004) A1012-A1019.

[4] L.M. L. Fransson, J. Vaughey, R. Benedek, K. Edstrom, J. O. Thomas, M. Thackeray Electrochem. Comm.
3 (2001) 317-323.

[5] D. C. S. Souza, V. Pralong, A. J. Jacobson, L. F. Nazar Science
296 (2002) 296, 2012.

[6] V. Aravindan , Y.-S. Lee, S. Madhavi Adv. Energy Mater. (2015) 1402225.

Figure 1
Improved Performance for Lithium Rich Layered Oxides Via High Throughput Technologies
Authors: Carroll Kyler J. , Li Bin , Strand Dee
Published: February 2020

The design of high voltage and high capacity cathode materials for lithium ion batteries is important for the pressing demands of both electric vehicles and portable devices. Lithium excess layered oxides, where the lithium-to-transition metal ratio is greater than 1, have been widely explored due to the possibility of utilizing more than 1 lithium in the chemical formula unit to significantly increase the capacity. Despite much research, commercial application of the lithium excess material has been impeded due to low initial coulombic efficiency, poor cycle life, voltage fade, and poor rate performance. These deficiencies have mainly been attributed to the complicated structural evolution and the formation of a cathode solid electrolyte interface (SEI) layer at higher voltages (>4.5V). Therefore, the role of surface modification on improving the electrochemical properties has been investigated by Wildcat.

The use of chemical treatments and post-annealing steps to induce the formation of a surface spinel structure prior to electrochemical cycling can improve the first cycle coulombic efficiency and rate performance. However, further improvements in the first cycle coulombic efficiency and cycle life of these materials are still required. This work investigates several families of surface coatings and compositional dopants in lithium rich layered oxides.  Modification of the surface coating and addition of dopants can greatly enhance the first cycle coulombic efficiency while also maintaining or improving cycle stability, voltage fade, and rate performance of the lithium excess material. Wildcat evaluation of the performance of hundreds of surface coatings and dopants shows that certain families tend to improve all metrics. In addition we have demonstrated that certain families, such as metal phosphate and metal fluoride coatings, reduce gas generation during the first cycle as well as subsequent cycles relative to the pristine lithium excess material.
Design and Processing of Advanced Lithium-Ion Electrode Materials
Authors: Yonemoto Bryan T , Shin Youngho , Croy Jason R. , Thackeray Michael M.
Published: February 2020

Significant interest in lithium- and manganese-rich (LMR) cathodes exists within the lithium-ion battery community. LMR electrodes, which incorporate a Li2MnO3 motif into the structure [1], exhibit high capacities and have relatively low raw materials costs [2]. Despite these attributes, significant challenges to commercialization remain, including industrial considerations related to materials processing. Synthesis of commercialized materials and electrodes such as those based on LiCoO2 (LCO) and LiNi­0.8Co0.15Al0.05O2 (NCA) has been highly optimized. However, less work has been done on the optimization and processing of promising new LMR compositions. Specifically, structurally-integrated “layered-layered-spinel” cathodes have been shown to provide improved rate capability, first-cycle efficiency, and possibly structural stability with cycling than their “layered-layered” counterparts [3]. However, these new chemistries have to date received little attention in the way of optimizing electrochemical performance through improved particle synthesis. This poster will detail important considerations for LMR particle synthesis through reactive crystallization, and highlight ongoing work at Argonne National Laboratory on the design and synthesis of advanced lithium-metal-oxide electrode materials.

References

M. M. Thackeray, C. S. Johnson, J. T. Vaughey, N. Li and S. A. Hackney, J. Mater. Chem. 15, 2257 (2005).

K. G. Gallagher, S. Goebel, T. Greszler, M. Mathias, W. Oelerich, D. Eroglu, V. Srinivasan, Energy & Environ. Sci. 7, 1555 (2014).

B.R. Long, J. R. Croy, J.S. Park, J. Wen, D.J. Miller and M.M. Thackeray, J. Electrochem. Soc. 161, A2167 (2014).

Acknowledgments

Funding for this work from the Office of Vehicle Technologies of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, is gratefully acknowledged.

The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Improving Rate Capability of Li-Ion Capacitors Using Nano Graphite Anodes
Authors: Aref Amir Reza , Chen Shih Wen , Lanagan Michael T. , Randall Clive A. , Rajagopalan Ramakrishnan
Published: February 2020

Li-ion capacitors are receiving considerable attention as potential energy storage device due to their high power density, high energy density, as well as long cycle life. The energy density of the capacitor is determined by the specific capacitance of high surface area double layer carbon cathodes while the power performance is dependent upon the rate capability of the anode. In this investigation, we demonstrate a high energy density lithium ion capacitor that can be charged and discharged between 2.2V – 4.2V with energy density exceeding 100 Wh/kg based on both the masses of the electrode and discharge time < 1 min can be fabricated. The capacitor was capable of being cycled at 1 A/g with 90% capacitance retention over 5000 cycles. The high voltage stability of the capacitor upto 4.2V was also determined using an accelerated floating voltage tests. The high performance of the capacitor was due to the use of a high purity polymer derived carbon cathode with controlled pore size distribution along with a nanocrystalline prelithated graphite as the anode.
Experimental and Theoretical Study of Fe-V Redox Flow Battery
Authors: Hammad Ahmad D , Souentie Stamatios , Amr Issam T , Alsuhaibani Abdulrahman S
Published: February 2020

Energy storage is currently one of the major challenges for the deployment of renewable resources. A low cost, flexible, large-scale technology is required to store and buffer the fluctuated electricity production rate. The Redox Flow Battery (RFB) is a very promising candidate with long life-span, high efficiency, and suitability for large scale energy storage, enhancing the reliability of the power grid, and promoting energy independence of remote areas. One additional substantial advantage of RFBs is that power and energy can be independently adjusted. The current cost of conventional flow battery systems is relatively high. This is due to the use of expensive vanadium-base electrolytes, along with Nafion-based membranes.

In this study, the V5+/V4+ redox couple has been replaced with the Fe3+/Fe2+, which results in significant cost reduction. The illustrated Fe-V battery employs an FeCl2 in HCl(aq) catholyte in one tank, and VCl3 in HCl(aq) anolyte in the other tank. A graphite electrochemical cell was equipped with a Nafion® 117 membrane, on which two carbon felt electrodes were attached. A galvanostat/potentiostat was used to apply constant currents and potentials. In this direction, an experimental and theoretical analysis of the iron-vanadium flow battery was carried out, investigating the effect of temperature, charge/discharge rate, and state of charge on the performance/efficiency of the energy storage system. To characterize the battery, voltage efficiency measurements and polarization curves were carried out at each point. In this way, the suitable operation SOC range for employed loads that the battery serves, can be defined for best voltage efficiency and power output.

The charge/discharge characteristics of the battery reveal an optimum operation temperature at ~47oC and an optimum charging current of ~50mA/cm2 for the state of charge range between 20% and 80%. Also, a small increase in the open circuit voltage with charging current was observed, indicating a slightly higher charging depth. The voltage efficiency as obtained by the finite-time galvanostatic charge and discharge cycles, strongly depends on the current J that is used. Efficiency measurements were performed for various SOC values using J from 300 to 800mA at 42oC. Moreover, voltage and coulombic efficiencies achieve up to 85%.

A mathematical model was built, based on the current exchange density obtained by the polarization curves for various operation conditions of the battery. The model concludes a negative asymmetry form to the energy barrier, to rate the determining half-reaction.
(Invited) Plasmon-Induced Charge Separation and Electric Field Localization
Authors: Tatsuma Tetsu , Saito Koichiro , Ishida Takuya , Nishi Hiroyasu
Published: February 2020

Plasmon-induced charge separation (PICS) occurs at the interface between plasmonic nanostructures of Au, Ag, or Cu and a semiconductor (e.g., TiO2).1-3 Carrier transfer from the nanostructure to the semiconductor due to external photoelectric effects (including hot carrier injection) or interfacial electron transition is responsible for PICS.4 We reported PICS for the first time more than 10 years ago1,2 and studied its mechanisms4,5 and applications.1,3,6,7 In particular, we have reported effects of localized electric field on PICS. In the case of PICS-based oxidation of Ag nanoparticles, anodic reaction (i.e., oxidation of Ag to Ag+) occurs preferentially at the sites where optical near field is localized.8-10 This may be explained in terms of ejection of energetic holes from the nanoparticles as Ag+ ions.10

1. Y. Tian and T. Tatsuma, J. Am. Chem. Soc., 127, 7632 (2005).

2. Y. Tian and T. Tatsuma, Chem. Commun., 2004, 1810.

3. T. Tatsuma, Bull. Chem. Soc. Jpn., 86, 1 (2013) [account].

4. E. Kazuma and T. Tatsuma, Adv. Mater. Interfaces, 1, 1400066 (2014).

5. H. Nishi and T. Tatsuma, Angew. Chem. Int. Ed., 55, 10771 (2016).

6. Y. Ohko, T. Tatsuma, T. Fujii, K. Naoi, C. Niwa, Y. Kubota, and A. Fujishima, Nat. Mater.,
2, 29 (2003).

7. Y. Takahashi and T. Tatsuma, Appl. Phys. Lett., 99, 182110 (2011).

8. E. Kazuma, N. Sakai, and T. Tatsuma, Chem. Commun., 47, 5777 (2011).

9. I. Tanabe and T. Tatsuma, Nano Lett., 12, 5418 (2012).

10. K. Saito, I. Tanabe, and T. Tatsuma, J. Phys. Chem. Lett., 7, 4363 (2016).
(Invited) Effects of Composition and Doping on the Optoelectronic Properties of Lead Halide Perovskite Nanocrystals
Authors: Robel Istvan , Makarov Nikolay S. , Liu Wenyong , Guo Shaojun , Pietryga Jeffrey M. , Klimov Victor I.
Published: February 2020

Colloidally synthesized lead halide perovskite nanocrystals have been recently demonstrated as active materials with great promise for a range of applications, from high-efficiency photovoltaics to color-converting phosphors and light-emitting diodes. Tailoring their optical and electronic properties through various synthetic routes in order to meet application-specific design parameters requires a good understanding of structure-property relationships. Here, by using a variety of steady-state and time-resolved spectroscopies, we explore carrier-carrier and carrier-dopant interactions in cesium lead halide nanocrystals as their halide component (Cl, Br, I, and their mixture) and doping level (Mn2+) is continuously tuned through a wide parameter space. We quantify such fundamental optical properties as exciton radiative lifetimes, absorption cross-sections, and derive the degeneracies of the band-edge electron and hole states. We also characterize the rates of intraband cooling and nonradiative Auger recombination and evaluate the strength of exciton–exciton coupling.1 Through impurity doping with Mn2+ ions, we also introduce new optical functionalities such as dual-color emission and establish the mechanism of carrier-dopant coupling in these materials.2

References:

1. N. S. Makarov, S. Guo, O. Isaienko, W. Liu, I. Robel, and V. I. Klimov, Spectral and Dynamical Properties of Single Excitons, Biexcitons, and Trions in Cesium–Lead-Halide Perovskite Quantum Dots, Nano Lett.
16, 2349-2362 (2016)

2. W. Liu, Q. Lin, H. Li, K. Wu, I. Robel, J. M. Pietryga, and V. I. Klimov, Mn2+-Doped Lead Halide Perovskite Nanocrystals with Dual-Color Emission Controlled by Halide Content, J. Am. Chem. Soc.
138, 14954-14961 (2016)
Excitonic Properties of 3D Hybrid Organic-Perovskites
Authors: Lauret Jean-Sébastien , Diab Hiba , Allard Gaëlle , Garrot Damien , Lédée Ferdinand , Deleporte Emmanuelle
Published: February 2020

A renewed interest in hybrid organic perovskites (HOPs) has emerged since 2012 following the increase of HOP solar cell efficiency. Despite the impressive performances of the devices, there is still lot of room for improvement. In particular, the development of applications will benefit of a better understanding of the photophysics of HOPs.

In this talk, we will discuss about the excitonic properties of CH3NH3PbI3 (MAPI) single crystals at low temperature, and compare them to those of thin polycrystalline films. The main feature is the appearance of a sharp emission line (FWHM ~ 5 meV) at high energy that is attributed to the free exciton signature, and which is completely absent in thin-films. The observation of the free excitonic emission in the low temperature phase allow to monitor the huge thermal broadening due to electron-LO-phonon coupling [1].

References:

[1] Hiba Diab, Gaëlle Trippé-Allard, Ferdinand Lédée, Khaoula Jemli, Christèle Vilar, Guillaume Bouchez, Vincent L.R. Jacques, Antonio Tejeda, Jacky Even, Jean-Sébastien Lauret, Emmanuelle Deleporte, and Damien Garrot, The Journal of Physical Chemistry Letters 7, pp 5093–5100 (2016)
(Invited) In-Situ Raman Observation of an Isolated Single-Walled Carbon Nanotube to Monitor Highly Localized Plasmon-Induced Reaction
Authors: Murakoshi Kei
Published: February 2020

Structural and electrical properties of an individual single-walled carbon nanotube (SWNT) was characterized by in-situ electrochemical surface-enhanced Raman scattering (EC-SERS) measurement. An isolated SWNT was supported on a well-defined Au nanodimer structure, which possesses a localized surface plasmon resonance (LSPR) field at the nanogap. Intense SERS spectra were measured for the SWNT at the gap region. The electronic structural change in an isolated SWNT by photo-indueed oxidation reactions was monitored as the function of the time and the light intensity. The results indicate that EC-SERS technique is a powerful tool for detailed analysis of the local density of the states under the excitation of SWNT by LSPR.
(Invited) Synthesis of Fine Controlled Sub-Nano Pt Particle As an Advanced Catalyst
Authors: Yamamoto Kimihisa
Published: February 2020

We show that tinchlorides, SnCl2 and FeCl3 complexes to the imines groups of a spherical polyphenyl- azomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. The metal-assembly in a discrete molecule can be converted to a size-regulated metal cluster with a size smaller than 1 nm as a molecular reactor. Due to the well-defined number of metal clusters in the subnanometer size region, its property is much different from that of bulk or general metal nanoparticles.

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. Organic inorganic hybrid versions have also been produced, by trapping metal ions or metal clusters within the voids of the dendrimers. Their unusual, tree-like topology endows these nanometre-sized macromolecules with a gradient in branch density from the interior to the exterior, which can be exploited to direct the transfer of charge and energy from the dendrimer periphery to its core.

Here we show that tin ions, Sn2+, complex to the imines groups of a spherical polyphenylazo- methine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By attaching an electron-withdrawing group to the dendrimer core, we are able to change the complexation pattern, so that the core imines are complexed last. By further extending this strategy, it should be possible to control the number and location of metal ions incorporated into dendrimer structures, which might and uses as high performance electronic devices, tailored catalysts, or fine-controlled clusters for advanced materials.
Synthesis and Property of Carbazole-Based Diporphyrins
Authors: Maeda Chihiro
Published: February 2020

Since carbazole is benzene-fused pyrrole, incorporation of a carbazole unit into fused porphyrinoids represents interesting possibilities. We have developed carbazole-based porphyrins which exhibited NIR absorption due to the quadruple benzo-fusion moieties. Following the successful synthesis, we have investigated the peripheral and core modifications and ring-expansion of the macrocycle as well as the applications to BODIPY derivatives. Furthermore, we recently synthesized carbazole-based diporphyrins to investigate the intramolecular electronic interactions. Here synthesis and photophysical property of carbazole-based diporphyrins are reported.
Transesterification As a Pretreatment to Bind an Anticorrosive Coating on an Aluminium Alloy
Authors: Paez Maritza Angelica , Muñoz Lisa , Gulppi Miguel , Tamayo Laura , Rabagliati Franco , Encinas Maria , Zhou Xiaorong , Thompson George
Published: February 2020

The conditions necessary to improve the adhesion of polymeric coatings to surfaces of aluminum alloys, AA2024-O (AA), were studied. The process considered a pre-conditioning of the metal surface by a transesterification reaction process with methyl methacrylate as an ester, by the generation of a terminal double bond on the surface of the alloy.

The potentiodynamic measurements show that coated specimens that were preceded by a transesterification process (AA-TE-PMMA), reveal a significantly lower corrosion current than those coated without transesterification pretreatment and a greater region of passivity.

From the analyzes obtained by XPS spectroscopy and also from the morphologies and thicknesses of the coatings obtained by SEM observations of the ultramicrotomed sections of the coated specimens, it is possible to infer the formation of a bond between the monomer group carrying the double bond and the metal surface. Furthermore, it is evident that the presence and lability of the double bond in the monomer, which functionalizes the surface, allows improving the adhesion of the polymer film, subsequently generated by radical polymerization. The protective capacity of the coating is even evident after 30 days of immersion in an aqueous solution of chloride.
(Invited) Electrical Atomic Force Microscopy for 2D Transition Metal Dichalcogenide Materials
Authors: Celano Umberto , Virkki Olli , Mascaro Marco , Mehta Ankit Nalin , Bender Hugo , Chiappe Daniele , Asselberghs Inge , Paredis Kristof , Hoflijki Ilse , Franquet Alexis , Huyghebaert Cedric , Radu Iuliana , Vandervorst Wilfried
Published: February 2020

As Si-based electronic devices are approaching their projected scaling limits, layered two-dimensional (2D) materials such as transition metal dichalcogenides (TMDs) are extensively studied as potential new channel materials and fundamental building blocks of emerging sensors and devices.[1-2] In this context, MoS2, WS2 and WSe2 to name a few, are now available for deposition trough different top down approaches. However, their outstanding properties are often degraded during the fabrication processes required for the device integration. For example, the selective growth of 2D TMDs their patterning and the electronics properties fine tuning still remain elusive. Here we report on electrical atomic force microcopy (AFM) and beam analysis techniques which are used to develop a framework of analysis for 2D materials. The latter is applied to understand the local properties of MoS2 comparing pristine material and structures which are selectively grown and patterned.[3] Different growth techniques are investigated. After modelling the tip-sample contact system, we assess the impact of the plasma-induced damages combining the electrical AFMs and Auger emission spectroscopy. We study the local electrical properties of grain boundaries and their transport respectively in pristine and patterned structures for FET devices by conductive atomic force microscopy (C-AFM).

[1] G. Fiori, F. Bonaccorso, G. Iannaccone, T. Palacios, D. Neumaier, A. Seabaugh, S. K. Banerjee, and L. Colombo, “Electronics based on two-dimensional materials,” Nat. Nanotechnol., vol. 9, no. 10, pp. 768–779, 2014.

[2] Desai, S. B., Madhvapathy, S. R., Sachid, A. B., Llinas, J. P., Wang, Q., Ahn, G. H., Javey, A. (2016). MoS 2 transistors with 1-nanometer gate lengths, 354(6308), 2–6.

[3] Chiappe, D., Asselberghs, I., Sutar, S., Iacovo, S., Afanas’Ev, V., Stesmans, A., … Thean, A. (2016). Controlled Sulfurization Process for the Synthesis of Large Area MoS2 Films and MoS2/WS2 Heterostructures. Advanced Materials Interfaces, 3(4), 1–10.
Improvement of Performance By Using Catalytically Etched Carbon Paper As Electrode for Vanadium Redox Flow Batteries
Authors: Abbas Saleem , Hwang Jinyeon , Mehboob Sheeraz , Shin Hyun-Jin , Ha Heung Yong
Published: February 2020

The environmental aspects of fossil fuels and depletion of their reservoirs are main reasons for the growing use of renewable energy sources and environmentally sustainable storage technologies in recent years. Solar, wind, biomass and tidal are among climate-friendly energy sources. But the integration of these sources into large scale grid application is limited by their intermittent nature. Electrical energy storage (EES) technology solves this issue by storing energy on large scales. Redox flow batteries (RFBs) due to unique advantages of design flexibility, long cycle life, decoupled scaling of power and energy, are amongst suitable candidates of EES. All Vanadium Redox Flow Battery (VRFB) introduced in 1980s by Maria Skyllas-Kzacos et al has advantage over conventional RFBs as it employs four different oxidation states of vanadium; V4+/V5+ to cathode side and V2+/V3+ to anode side hence minimizes crossover effect through membrane. A typical VRFB contains two electrolyte reservoirs connected to cell sandwiching an ion exchange membrane between electrodes. V4+ is oxidized to V5+ on cathode while V3+ is reduced to V2+ on anode during charging and these charged species are reversed back during discharging.

Carbon paper or felt due to its large reactive surface area, chemical stability in highly acidic solution has been widely used as electrode in VRFB, however poor electrochemical activity, low kinetics toward oxidation and reduction of vanadium ions, and less wettability arising from its hydrophobic nature limit its wide-spread application. Several modification techniques have been used to improve the catalytic activity of carbon electrode toward vanadium redox couples mainly including thermal, chemical and electrochemical treatments. Most of the modification techniques result increased activity of carbon electrode attributed to its enhanced available surface area and surface functional groups. In this work carbon paper is etched by using cobalt oxide (Co3O4) as catalyst and is used as electrode for vanadium redox flow battery cell. The etched carbon paper is found better than pristine one in terms of charging overpotential, IR drop, charge/discharge capacities and energy efficiency at all working current densities. Etched carbon paper showed almost 31.0 Ah/L discharge capacity at initial working current density of 50 mA/cm2 compare to 16.0 Ah/L of pristine one, While 16 Ah/L at 150 mA/cm2 where pristine and thermally treated (TT) carbon paper have no performance. Similar effect was noticed in terms of energy efficiency, the etched carbon paper showed 70% energy efficiency at 150 mA/cm2 which is dramatically higher than pristine and thermally treated carbon paper electrodes. The improved performance is attributed to increased surface area, wettability and presence of microscopic pores on the surface of etched carbon paper.
Unsupported Two-Dimensional Ni-Pt Nanoframes with High Activity and Stability Towards the Oxygen Reduction Reaction
Authors: Godinez Fernando Fernando , Rhodes Christopher
Published: February 2020

Currently, supported platinum (Pt) and Pt-based alloys are used as oxygen reduction reaction (ORR) electrocatalysts for commercial proton exchange membrane fuel cells (PEMFCs) for vehicles, back-up power, and other applications. Carbon black is a traditional support material because of its high surface area and electronic conductivity, however carbon corrosion highly affects the long-term stability compromising fuel cell performance under operational conditions. To improve stability, the replacement of carbon with more resistant supports or the use of unsupported catalysts can contribute to increase the stability and performance of these materials. Here, we present the synthesis and characterization of two-dimensional (2D) bimetallic NiPt nanostructures that function as unsupported (carbon-free) electrocatalysts with both significantly higher catalytic activity and stability compared with conventional Pt/carbon electrocatalysts for the ORR. The nanoframes consist of a hierarchical 2D framework composed of a highly catalytically active Pt-Ni alloy phase with an interconnected solid and pore network that results in three-dimensional molecular accessibility. The physicochemical properties were modulated by controlling the synthesis parameters and atmospheric and thermal treatment conditions. The unsupported metallic nanoframes allowed the improvement of ORR specific activity by almost one order of magnitude compared to commercial Pt/C. In addition to higher activity, accelerated stability testing showed that the metallic Ni-Pt nanoframes exhibit significantly improved (86% higher) stability compared with Pt/carbon catalysts (43%). Analysis of the electrochemical reaction kinetics using the Tafel slopes and rotating ring-disk electrode (RRDE) experiments supports that at low overpotentials the first electron transfer is the rate determining step and the oxygen reduction reaction proceeds mainly by four electron transfer on the Ni-Pt nanoframes. The ability to create metallic 2D structures with 3D molecular accessibility opens up new opportunities for the design of high activity and stability carbon-free catalyst nanoarchitectures for numerous electrocatalytic and catalytic applications.

Figure 1