bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Structure and Properties of Electrolyte Solutions Based on Fluorinated Alkylphosphates As Nonflammable Solvents for Lithium-Ion Batteries
Authors: Todorov Yanko , Fujii Kenta , Aoki Masahiro , Mimura Hideyuki , Yoshimoto Nobuko , Morita Masayuki 
Published: February 2020

It has become more important to establish safety and reliability in lithium-ion battery (LIB) technology, especially for developing large-scale and higher energy density systems. Nonflammable organic solvents are considered to be safer components in LIBs [1]. Fluorinated ethers, carbonates and phosphates have been examined as possible candidates that consist of nonflammable electrolyte solutions. Among them, fluorinated alkylphosphates (FAPs) show excellent nonflammability as well as good compatibility with materials used in LIBs [2, 3]. In the present paper, ionic structure and basic characteristics of the electrolyte solutions composed of FAPs dissolving lithium salts are reported.
Tris(2,2,2-trifluoroethyl) phosphate (TFEP) and bis(2,2,2-trifluoroethyl)-ethyl phosphate (BTEP) as FAP were used as the nonflammable solvent. Triethylphosphate was also used for comparison. Ionic conductivity and viscosity were measured for the electrolytic solutions dissolving lithium salts with different anions. The Walden’s product (conductivity ´ viscosity) of the electrolytic solution was analyzed to discuss the ionic structure depending on the combination of the solvent and the salt (anion). Although the most of lithium salts dissolve with considerable concentration, eg. ~0.6 mol dm-3 (M) for LiPF6 in TFEP and > 0.6 M for other LiX/FAP combinations, the conductance behavior of the solution suggested that rather strong ionic interactions, or ion-association, will exist over wide salt-concentration range. The ionic structure of each electrolyte system, including the coordination of solvent and anion to Li+ cation (solvation), was further examined by spectroscopic measurements (ATR-IR and Raman). The analyses of the spectroscopic data gave different solvation structures that are strongly dependent on the combination of the solvent and the salt.
Thermal analyses of the electrolyte systems consisting of FAP solvents were conducted by DSC. Conventional alkylcarbonate-based electrolyte solution showed highly exothermic behavior above ca. 200 °C under the contact with charged (oxidized) positive electrode, whereas the TFEP-based electrolyte solution behaved stably up to 310 °C and gave smaller quantity of total exothermic heat than alkylcarbonate solution did. The above experimental results proved that FAP-based solvents give safer electrolyte system for larger-scale LIBs.

[1] M. Ue, et al., in “Modern Aspects of Electrochemistry, Vol 58; Electrolytes for Lithium and Lithium-ion Batteries” (T. R. Jow, et al., editors), Ch. 2, p.93, Springer (2014).
[2] T. R. Jow, et al., J. Electrochem. Soc., 149, A1489 (2002); 150, A161 (2003); 150, A171 (2003).
[3] H. Nakagawa, et al., J. Electrochem. Soc., 161, A480 (2014).

Figure 1
(Invited) Electrolyte Additives for High-Voltage Lithium-Ion Battery Cathodes
Authors: Passerini Stefano , Birrozzi Agnese 
Published: February 2020

In order to increase the energy density of lithium-ion batteries, novel cathode materials have attracted much attention due to their high operating voltage [1]. However, their practical application is still limited due to the poor stability of the cathode / alkyl carbonate-based electrolyte interface. In fact, the working potential of many high voltage cathode is beyond the electrochemical stability window of the conventional carbonate-based electrolytes (< 4.3 V vs. Li+/Li), thus leading to the electrolyte oxidative decomposition [2]. This phenomenon, besides reducing the energy stored in the cell, might even results in the formation of decomposition products (e.g., HF) leading to metal dissolution, and hence material capacity fading.
Many strategies, such as the use of alternative electrolyte system or the coating of the material, have been proposed in order to enable the use of high-voltage cathodes [3]. However, using electrolyte additives is one of the most efficient and economic strategy for alleviating the undesired reactions among cathode and electrolyte [4]. In fact, electrolyte additives can be sacrificially decomposed to form a protective layer on cathode surface, thus avoiding further electrolyte decomposition reactions. In addition, electrolyte additives can even scavenge water or other impurities and/or stabilize the lithium salt, extending therefore the cycle life of the high-voltage cathodes.
In this study, the investigation of additives’ effects in enhancing the cathode cycling stability and efficiency will be presented via a combination of electrochemical techniques, such as impedance spectroscopy and ex-situ analytical techniques, i.e. XRD, XPS and RAMAN. The feasibility of the electrolyte additives employment for practical application will be demonstrated showing full-cell studies with graphite as anode.
[1] A. Kraytsberg, Y. Ein-Eli, Advanced Energy Materials, 2 (2012) 922-939.
[2] S. Tan, Y.J. Ji, Z.R. Zhang, Y. Yang, ChemPhysChem, 15 (2014) 1956-1969.
[3] N.-S. Choi, J.-G. Han, S.-Y. Ha, I. Park, C.-K. Back, RSC Advances, 5 (2015) 2732-2748.
[4] S.S. Zhang, J. Power Sources, 162 (2006) 1379-1394.
In Situ Electrochemical Measurements of Deposition and Dissolution of Lithium in Li[N(CF3SO2)2]-Glyme Solvate Ionic Liquids
Authors: Tachikawa Naoki , Hosoda Shin , Ishida Takuya , Yoshii Kazuki , Watanabe Masayoshi , Katayama Yasushi 
Published: February 2020

The equimolar mixture of lithium bis(trifluoromethylsulfonyl)amide (LiTFSA)-tetraglyme (G4) has been known as a solvate ionic liquid consisting of [Li(G4)]+ and TFSA–. This solvate ionic liquid contains lithium ions in high concentration (ca. 3 mol dm–3) and has negligible vapor pressure at ambient temperature. It has been reported that the solvate ionic liquid is compatible with sulfur cathode because of the low solubility of lithium polysulfides [1]. To achieve the high energy density of the rechargeable Li-S batteries, it is required to investigate anode materials having high specific capacity such as a lithium anode. In this study, the initial stage of deposition of lithium was investigated in the solvate ionic liquids with different compositions using electrochemical quartz crystal microbalance (EQCM) and optical microscope.
LiTFSA-G4 solvate ionic liquids were prepared by mixing LiTFSA and G4 at different molar ratios of LiTFSA (X
LiTFSA) in an Ar filled glove box. The potentials of Li(I)|Li were evaluated using a Ag|Ag(I) reference electrode, which consisted of a silver wire immersed in 50.0-50.0 mol% LiTFSA-G4 containing 0.1 mol dm–3 AgCF3SO3. EQCM measurement was performed with an airtight three-electrode cell. A Cu coated quartz crystal electrode was used as a working electrode. Lithium was used as a reference and counter electrode.
[Li(G4)]+ is considered a major lithium species in LiTFSA-G4 solvate ionic liquid at X
LiTFSA = 50 mol%. On the other hand, both [Li(G4)]+ and [Li(TFSA)2]– are expected to exist in LiTFSA-G4 solvate ionic liquid at X
LiTFSA > 50 mol%. It was found that the potential of Li(I)|Li in the LiTFSA-G4 solvate ionic liquid at X
LiTFSA > 50 mol% was given by an equilibrium, [Li(TFSA)2]– + e– = Li + 2TFSA–, indicating the active lithium species is [Li(TFSA)2]– rather than [Li(G4)]+. Li was deposited at a current density of –0.01 mA cm–2. The electric charge for deposition was –0.05 C cm–2. In the case of 54.5-45.5 mol% LiTFSA-G4 solvate ionic liquid, Li was deposited sparsely on the Cu electrode surface and grew as a whisker-like shape. On the other hand, whisker-like Li deposit was not observed in 50.0-50.0 mol% LiTFSA-G4 solvate ionic liquid where Li nuclei were uniformly generated on the electrode surface. These results suggest that the nucleation and crystal growth of Li are affected by the composition of the solvate ionic liquids, resulting in the morphology change of Li deposits.
Acknowledgment
This study was supported by the Advanced Low Carbon Technology Research and Development of Program (ALCA) of the Japan Science and Technology Agency (JST).
Reference
[1] K. Dokko et al., J. Electrochem. Soc., 160, A1304 (2013).
Novel Carbonate-Based Polymer Electrolytes for All-Solid-State Li Batteries
Authors: Tominaga Yoichi 
Published: February 2020

Solid polymer electrolytes (SPE) such as poly(ethylene oxide) (PEO)-metal salt complexes are of great interest to replace typical liquid electrolytes for batteries because of their flexibility and lightweight. However, the ionic conductivity of PEO-based electrolytes is limited to approximately 10-5 S/cm at room temperature, and it is extremely difficult to enhance the lithium (cation) transference number. So we consider polycarbonates that can be obtained by the alternating copolymerization of CO2 with epoxides and comprise novel polymer candidates for SPE. This CO2/epoxide copolymer is a remarkable macromolecule because it utilizes CO2 as a raw material and has excellent properties; it is biodegradable, easily processed and colored, and has high transparency and low oxygen permeability. We have focused on the chemical structure of the copolymer, which has one alternating carbonate group (-O-(C=O)-O-) in each repeating unit of the main chain. The carbonate group has a large dipole moment, and it may dissolve many types of salts. Carbonate-based organic solvents, such as dimethyl carbonate, are used as the electrolyte solution in Li-ion batteries because of their high dielectric constant. We therefore consider that the carbonate-based polymer can be a suitable framework for SPE and can provide suitable polar environment for dissolved ions. In this study, we used commercial polycarbonates such as poly(ethylene carbonate) (PEC) and novel polycarbonates having side groups synthesized in our laboratory. We found extraordinary and unique properties of carbonate-based electrolytes that the conductivity of PEC-Li salt electrolytes increases with increasing salt concentration and the Li transference numbers were extremely higher than those of typical polyether system. Polycarbonates having short oxyethylene (OE) side chains were synthesized, and we revealed that the LiFSI electrolytes having longer OE groups have high conductivity at low salt concentrations, and the conductivity increases dramatically at high salt concentrations. A Li|PEC-LiFSI|LiFePO4 cell with 3DOM polyimide membrane delivered a reversible charge-discharge capacity around 120 mAh g-1 at 30 oC and C/20 rate.
This study was supported financially by the Specially Promoted Research for Innovative Next Generation Batteries of the Advanced Low Carbon Technology Research and Development Program (ALCA-SPRING) of JST and the Grant-in-Aid for Scientific Research (B) of JSPS KAKENHI (No. 25288095, 16H04199), Japan. The 3DOM polyimide matrix was kindly donated from Prof. Kiyoshi Kanamura and Dr. Hirokazu Munakata of Tokyo Metropolitan University, Japan.
References: Electrochem. Commun., 66, 46 (2016), Polymer, 84, 21 (2016), Macromol. Chem. Phys., 216, 1660 (2015), J. Electrochem. Soc., 162, A3133 (2015), Chem. Commun., 50, 4448 (2014), Polym. J., 44, 1155 (2012), Electrochim. Acta, 57, 36 (2011), Polymer, 51, 4295 (2010).
(Invited) in Situ Functional Imaging of Electrodes for All-Solid-State Batteries
Authors: Leite Marina S. 
Published: February 2020

To date, the development of higher performance Li-ion all-solid-state batteries still entails the complete understanding of how the electrolyte and electrode materials change upon lithiation/delithiation. While macroscopic voltammograms are extremely informative, they do not provide information about how the material composing the active layers of the battery is changing upon lithiation/delithiation. Thus, to probe the mesoscale behavior of the batteries we combine real-time scanning electron microscopy in ultra-high vacuum with electrochemical cycling, in addition to ex situ characterization of the morphological, chemical, and electrical changes of the anodes and electrolyte upon lithiation. In particular, we will discuss the results using LiCoO2 (cathode), LiPON (electrolyte, deposited via sputtering), and Al and Si (anode) [1,2]. In the anode, Li ions are trapped by an AlLi alloy capped by a stable Al-Li-O is formed, leading to a rapid capacity fade, from 48.0 to 41.5 μ.Ah/cm2 in two cycles [1]. Surprisingly, the addition of a Cu protective layer is insufficient to avoid the device degradation because of the ultra fast Li diffusion within Al. Nevertheless, the Si anodes present extremely stable cycling: >92% of capacity retention after 100 cycles, with average Coulombic efficiency of 98% [2]. The in situ functional imaging platform presented here paves the way to diagnosing in real-time the changes that take place in all-solid-state batteries.
[1] M. S. Leite et al., J. Mater. Chem. A. 2, 20552 (2014). Inside Cover.
[2] C. Gong et al., ACS Appl. Materials and Interfaces. 7, 26007 (2015). Cover.
Quasi-Solid State Electrolytes for Li-Ion Battery Applications
Authors: Honma Itaru , Matsuo Takahiro , Unemoto Atsushi , Gambe Yoshiyuki 
Published: February 2020

High energy density secondary batteries are key devices for mobile industrial applications such as electric vehicles, drones and robots. Among attractive new device concepts such as lithium- air, lithium- sulfur, Na/Mg ion and all solid state battery (ASSB), ASSB has been considered to be most promising due to their higher energy density, higher cell output voltage and superior chemical/thermal safety. In this paper, our original approach to electrolyte materials are reported, which are synthesized by hybridization of ionic liquid and nanoparticles. In fact, the quasi-solid state electrolytes have been made by solidification of Li ion conducting ionic liquid by mixing with SiO2 nanoparticles due to strong interaction between ionic liquid molecules and SiO2 surface, which resulted in the electrolytes having liquid-like ionic conductivities in their solid state matrix. All solid state Li battery cell consisting Li metal anode/quasi-solid state electrolytes/LiFePO4 cathode have been successfully fabricated and demonstrated stable charge /discharge cycles more than a thousand under 1.0C-rates in spite of their solid state cell design. More importantly, it has been demonstrated for the first time, bipolar stacked tripled cells with multiple voltages up to 10V are successfully demonstrated on the coin cell CR2032 devices.
references
[1] Seitaro Ito, Atsushi Unemoto, Hideyuki Ogawa, Takaaki Tomai, and Itaru Honma, J. Power Sources, 2012, 208, 271
[2] Atsushi Unemoto, Hideyuki Ogawa, Seitaro Ito and Itaru Honma, J. Electrochemical Society, 2013, 160, A138
[3] Takaharu MATSUO, Yoshiyuki GAMBE and Itaru HONMA, Scientific Reports,2014,4,6084
[4] Yoshiyuki Gambe, Yan Sun and Itaru Honma, Scientific Reports, 2015, 5, 8869

Figure 1
Activity and Selectivity of Ni-Fe Layered Double Hydroxide Electrocatalyst for Seawater Electrolysis
Authors: Dionigi Fabio , Reier Tobias , Gliech Manuel , Kühl Stefanie , Strasser Peter 
Published: February 2020

Electrochemistry will play a critical role in the development of future sustainable energy storage and conversion technologies, where new functional nanocatalyst materials are the key components for application in fuel cells and electrolyzers. In this context, the generation of hydrogen and oxygen from seawater electrolysis is an attractive process for fuel production since the majority of liquid water available to mankind at the earth's surface is salty water [1]. Unfortunately, chlorine evolution reaction (CER) is a competing reaction to oxygen evolution reaction (OER) when seawater is used as electrolyte.
Although OER is thermodynamically favored over CER, the poor kinetics of the OER makes CER the dominant reaction in many catalytic systems. NiFe layered double hydroxide (LDH) has been reported to catalyze the OER reaction in alkaline media at low overpotentials comparable with the performance of noble metals catalysts [2]. In our study, its activity and stability for seawater oxidation have been investigated with a rotating disk electrode in chloride containing electrolytes with basic and slightly basic pH. The electrochemical experiments are combined with products analysis (Figure 1) in order to estimate the selectivity for oxygen evolution. In particular, CER and hypochlorite formation are investigated by an in-line quadrupole mass spectrometer (QMS) and iodometric titration respectively.
NiFe LDH shows a high selectivity for OER in alkaline electrolytes (pH 13) containing 0.5 M NaCl, a chloride ions concentration typical of seawater. In 0.3 M borate buffer (pH 9.2) with 0.5 M NaCl the electrochemical experiments show degradation in performance at current densities approaching 10 mA/cm2, despite the high selectivity at lower current densities. This degradation of the anodic current is not observed in pH 13 (0.1 M KOH) in the presence of the same concentration of NaCl.

References

[1] H.K. Abdel-Aal, K.M. Zohdy, M. Abdel Kareem, Hydrogen Production Using Sea Water Electrolysis, The Open Fuel Cells Journal, 3 (2010) 1-7.
[2] M. Gong, Y.G. Li, H.L. Wang, Y.Y. Liang, J.Z. Wu, J.G. Zhou, J. Wang, T. Regier, F. Wei, H.J. Dai, An Advanced Ni-Fe Layered Double Hydroxide Electrocatalyst for Water Oxidation, J Am Chem Soc, 135 (2013) 8452-8455.
Electrochemical Membrane Reactor for Hydrogen & Syn Gas Fabrication
Authors: Yoon Sung Pil , Han Jonghee , Nam Suk Woo , Ham Hyung Chul 
Published: February 2020

Energy conversion & storage from renewable sources is an issue because of their unstable supply. The production of hydrogen from renewable resources is one of the candidates, becoming a highly researched field around the world. However, water electrolytic hydrogen is so far the most practical and promising technology for large-scale renewable hydrogen production. Among the water electrolytic hydrogen productions, solid oxide electrolyzer cells (SOECs) are the most promising technology because SOEC can produce hydrogen at a higher chemical reaction rate with a lower electrical energy requirement. For example, SOECs can produce about 40% more hydrogen from a given energy input than a conventional water electrolysis system. One of the technical hurdles is to maintain the high operating temperature due to the high endothermic reaction of water electrolysis. Recently, in order to improve the hydrogen production efficiency, SOECs has considered using heat from nuclear energy and geothermal energy.
In this experiment, we have tried to develop an electrochemical membrane reactor for both hydrogen & syn-gas fabrication. In this system, water can be electrolyzed at the SOFC anode part and methane can be partial oxidized at the opposite electrode to produce syn-gas. The advantages of this system can reduce the need of additional heat because of exothermic reaction of methane POX. Also, the methane POX with pure oxygen from the electrolyzer cell can produce the syn-gas with a H2/CO ratio of 2, which is suitable for methanol GTL process. We can further discuss operating results of the system at the meeting.

Figure 1
3D Printed Reversible Solid Oxide Electrochemical Reactors
Authors: Farandos Nicholas Michael , Kleiminger Lisa , Kelsall Geoff H. 
Published: February 2020

The increasing penetration of intermittent energy sources into electricity grids worldwide necessitates deployment of large-scale energy storage facilities to ensure that the balance between energy supply and demand can be managed over a range of time scales. Reversible, high-temperature solid oxide electrochemical reactors with oxide ion-conducting electrolyte, such as yttria-stabilized zirconia (YSZ), can convert electrical energy to chemical energy, and vice versa, with roundtrip efficiencies of ca. 70 %,[1] depending on current densities, for splitting of CO2 and H2O to CO and H2, respectively, and oxygen.
Electrolysis at high current densities over long times necessary for inter-seasonal energy storage results in severe microstructural degradation at the oxygen electrode, lanthanum strontium manganite (LSM)| YSZ | pore interface, the so called triple phase boundary (TPB). This is due to delamination, as a result of pressures associated with O2 accumulation in non-percolating voids.[2] Therefore, greater control over microstructure could eliminate these non-percolating voids, decreasing degradation rates.
We are investigating inkjet printing to fabricate oxygen-electrode architectures with exquisitely controlled microstructures, in order to minimise the probability of non-percolating pores. The first step was formulation of a printable YSZ ink that was printed to form the sintered scaffold structures, shown in Figure 1. A printable LSM ink was formulated, printed into the pillar-scaffold structure and subsequently heat-treated to form the composite electrode, comprised of a close-packed cylinder array (Figure 2a). Electrochemical performance data of the resulting cell in electrolyser mode will be presented, and compared with model predictions (Figure 2b).

References

1. S. H. Jensen, C. Graves, M. Mogensen, C. Wendel, R. Braun, G. Hughes, Z. Gao, S. A. Barnett, Energy Environ. Sci.,
8, 2471. (2015).
2. C. Graves, S. D. Ebbesen, S. H. Jensen, S. B. Simonsen, M. B. Mogensen, Nat. Mater.
14, 239. (2015).
3. B. Kenney, K. Karan, Solid State Ionics,
178, 297. (2007).

Figure 1
(Invited) Reverse Electrodialysis for Unique Devices
Authors: Kwon Seung-Ryong , Baek Seol , Kim Ji Tae , Jeon Joohee , Seo Daye , Chung Taek Dong 
Published: February 2020

Reverse electrodialysis (RED) is emerging as one of the promising process for generating electrical power from renewable energy sources. Production of electrical power was demonstrated by mixing the fresh and salt water which are inexhaustible resources at the mouth of river for the first time in early 1950s. This idea had not been receiving keen attention, however, before we seriously faced the depletion crisis of natural power resources. Recently, a couple of European countries, including Netherland, Sweden, and Italy, have been interested in the study and development of salinity gradient power-based electricity production systems. For instance, Wetsus center in Netherland built up experimentally and theoretically optimized RED systems to obtain maximum electrical power for sustainable water technology with given materials and mechanical engineering resources. They are developing the pilot RED plant capable of 200 MW electricity production and ultimately planning to supply local public/private housing. Meanwhile, some scientists paid attention to unique applications based on eco-friendly RED systems. As an application, Logan group at Pennsylvania State University showed significantly increased electricity production with simultaneous purification of waste water using the hybrid system of RED and microbial cell. They also reported the hydrogen production strategy by generating electricity in the same combinations. In this talk, a few unique applications based on RED system as a new electrical power source are introduced and discussed.