bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Solubility and Vapor Pressure of Electrolytes Based on Alkylcarbonates Containing Litfsi, Lifap, and LiPF6 Lithium Salt: Measurement and Prediction
Authors: Dougassa Yvon rodrigue , Porion Patrice , Jacquemin Johan , El watani Loubna , Tessier Cécile , Anouti Mérièm 
Published: February 2020

Most liquid electrolytes used in commercial lithium-ion batteries are composed by alkylcarbonate mixture containing lithium salt. The decomposition of these solvents by oxidation or reduction during cycling of the cell, induce generation of gases (CO2, CH4, C2H4, CO …) increasing of pressure in the sealed cell, which causes a safety problem [1]. The prior understanding of parameters, such as structure and nature of salt, temperature pressure, concentration, salting effects and solvation parameters, which influence gas solubility and vapor pressure of electrolytes is required to formulate safer and suitable electrolytes especially at high temperature.
We present in this work the CO2, CH4, C2H4, CO solubility in different pure alkyl-carbonate solvents (PC, DMC, EMC, DEC) and their binary or ternary mixtures as well as the effect of temperature and lithium salt LiX (X = LiPF6, LiTFSI or LiFAP) structure and concentration on these properties. Furthermore, in order to understand parameters that influence the choice of the structure of the solvents and their ability to dissolve gas through the addition of a salt, we firstly analyzed experimentally the transport properties (Self diffusion coefficient (D), fluidity (h

-1
), and conductivity (s) and lithium transport number (tLi
) using the Stock-Einstein, and extended Jones-Dole equations [2]. Furthermore, measured data for the of CO2, C2H4, CH4 and CO solubility in pure alkylcarbonates and their mixtures containing LiPF6; LiFAP; LiTFSI salt, are reported as a function of temperature and concentration in salt. Based on experimental solubility data, the Henry’s law constant of gases in these solvents and electrolytes was then deduced and compared with values predicted by using COSMO-RS methodology within COSMOthermX software. From these results, the molar thermodynamic functions of dissolution such as the standard Gibbs energy, the enthalpy, and the entropy, as well as the mixing enthalpy of the solvents and electrolytes with the gases in its hypothetical liquid state were calculated and discussed [3]. Finally, the analysis of the CO2 solubility variations with the salt addition was then evaluated by determining specific ion parameters Hi
by using the Setchenov coefficients in solution. This study showed that the gas solubility is entropy driven and can been influenced by the shape, charge density, and size of the anions in lithium salt.
References
[1] S.A. Freunberger, Y. Chen, Z. Peng, J.M. Griffin, L.J. Hardwick, F. Bardé, P. Novák, P.G. Bruce, Journal of the American Chemical Society 133 (2011) 8040-8047.
[2] P. Porion, Y.R. Dougassa, C. Tessier, L. El Ouatani, J. Jacquemin, M. Anouti, Electrochimica Acta 114 (2013) 95-104.
[3] Y.R. Dougassa, C. Tessier, L. El Ouatani, M. Anouti, J. Jacquemin, The Journal of Chemical Thermodynamics 61 (2013) 32-44.
XRF-Microanalysis of Electrodes for Li-Ion Batteries
Authors: Boesenberg Ulrike , Falk Mareike , Menzel Magnus , Janek Jürgen , Falkenberg Gerald , Fittschen Ursula Fittschen Elisabeth 
Published: February 2020

Spatial correlation between morphological properties and chemical phase visualizes transport mechanism and phase transformations, e.g. in electrodes for Li-ion batteries. This can help to find origin of aging and failure mechanism and finally, to build better batteries. Quasi nondestructive micro X-ray fluorescence analysis allows for in operandoand intermediate stages investigations such as elemental migration and can reveal structure-properties relationships while keeping the sample in a well-protected environment. Making use of the fairly large penetration length of the X-rays, representative volumes of the electrodes can be studied. The method is extremely suitable to correlate the spatial distribution of two or more elements.
Cutting edge instrumentation in this field is the MAIA fluorescence detector which allows for ultra fast mapping of areas of multiple mm² area with sub-micron resolution within minutes. This allows examination of full electrodes. The backscattering geometry of the detector enables easy mounting of flat samples such as electrodes or pouch-cells. By variation of the energy in the vicinity of an absorption edge, conclusions on local variations of the state of charge can be drawn, probing the oxidation state of the redox-active element.
For the present study, samples of LiNi0.5Mn1.5O4 electrodes cycled vs. Li were investigated at beamline P06 at DESY, Hamburg Germany. The experiment revealed significant inhomogeneities in the local Ni/Mn ratio upon cycling which is correlated to thinning of the electrode. Higher cycling rates showed an increased impact and higher material losses. Inhomogeneities in the phase transformation were also found during the charge and discharge process. This method is by no means limited to the investigated material, but is easily applicable to other transition metals.
Facile Polymer/Carbon Electrodes Fabrication for Low-Cost, High-Energy Supercapacitors
Authors: Arcila-Velez Margarita Rosa , Roberts Mark E. 
Published: February 2020

Due to their potential for combined high power and high energy, supercapacitors provide exciting opportunities for future energy storage systems. Limitations in material performance and processing must be overcome to achieve large-scale manufacturing and utilization. Activated carbon has found application in supercapacitors due to its large surface area and chemical stability, however their energy density is limited by their electrochemical double layer capacitance, which depends on surface area. Conducting polymers (CPs), on the other hand, can store charge through Faradaic processes, which allows more efficient material utilization. Commercial application requires advances in continuous manufacturing methods and material performance, including cycle stability, charge capacity and operating potential.
In the past decade, research on CPs has focused on achieving nanostructured electrodes by modifying the synthesis processes to increase mechanical, electrical and electrochemical properties. An alternative is to incorporate a complementary material to reinforce the polymer structure, and carbon nanotubes (CNTs) provide a suitable option due to their superior mechanical properties, electronic conductivity and chemical stability. Composite materials can be engineered with CPs and CNTs to achieve significant property enhancement. The combination of conducting polymers with carbon materials has been studied in the past to enable the use of CPs in commercial supercapacitors, by making electrode material more stable, lighter, stronger and tougher. CNTs improve the cycle life and mechanical properties of CP since they can adapt easily to changes in volume, and also introduce new electronic properties based on interactions between the two compounds. On the other hand, CPs enhance the charge storage capacity and capacitance of CNT materials and can help overcome their bundling and aggregation.
In this work, we prepared free-standing CNTs/CP composite electrodes in a fast and scalable process by dispersing CNTs and CPs in suspension, filtering the mixture through a membrane and peeling off the dried filtrate. This process eliminates the need for a binder, substrate or additional processing and pressing, which can affect the properties of the material. These composite electrodes showed specific capacitances as high as 366 F/g. CNTs work well as both anode and cathode materials for supercapacitor devices due to their wide potential stability, and when combined with the appropriate redox polymer, high performances can be obtained. Asymmetric CNTs/CP supercapacitor cells fabricated with polymer-CNT cathodes and anodes exhibited high power and high energy densities, especially when compared to pure CNT and good cycling stability. Given the process simplicity, relatively low cost and high throughput, the present composites have great potential for large-scale CP/CNTs supercapacitor production.
Low Cost, Low Surface Area Activated Carbon As Anode Material for Neutral pH Aqueous Asymmetric Supercapacitor Applications Via a Simple Surface Modification
Authors: Shanbhag Sneha , Whitacre Jay 
Published: February 2020

Surface modified activated carbon has been developed for use as a low-cost electrode material in aqueous asymmetric electrochemical supercapacitors. Specifically, wood-based activated carbon with a surface area of under 500 m2/g was modified using an intermediate temperature acid exposure step that more than doubled the specific capacitance in a neutral aqueous electrolyte. After the modification step, the carbon was analyzed using x-ray photoelectron spectroscopy, BET, and combustion analysis. The material thus developed gave approximately 200% improvement in the specific capacitance in 1 M Na2SO4; namely 109 F/g when compared against the precursor activated carbon which showed 38 F/g. To prove the possible utility of this material, full asymmetric energy storage cells were made using the modified carbon as the anode active material and Lithium Manganese Oxide as the cathode active material and Na2SO4 aqueous electrolyte. The test cells displayed excellent reversible capacity greater than 40 Ah/kg of activated carbon in anode for over 1000 cycles, which is an effective capacitance of approximately 160 F/g delivered over relatively slow charge/discharge rates. A Simple economic analysis shows that this material is over an order of magnitude more cost effective on a $/Ah basis than off-the-shelf electrochemical double-layer capacitor materials. These encouraging results show great promise in developing low cost energy storage devices while incorporating non-toxic and environmentally benign materials.

Figure 1
An Efficient Solar Energy Storage System: All Vanadium Redox Photoelectrochemical Cell
Authors: Wei Zi , Liu Dong , Chia-jen Hsu , Shen Yi , Liu Fuqiang 
Published: February 2020

Environmental pollution has been a severe issue for mankind and the immediate impact on our lives includes global warming as well as poor air quality. Besides, energy crisis attracts a lot concern as our demands for energy increase while the available energy resources are near depletion.
A popular candidate that can be a solution for the above-mentioned problems is solar energy, a typical kind of renewable energy resource. The current obstacle to fully utilize sun light is the lack of efficient method to store it due to its intermittent nature. [1]
In this study, we demonstrated a novel solar energy storage system — an all vanadium redox photoelectrochemical storage (All-V-PECs) cell, which could be a viable solution for sustainable storage & utilization of solar energy. Herein, we combined an all vanadium redox flow battery with a photoelectrochemical cell in an All-V-PECs cell, where vanadium redox species served as the energy storage media while photoelectrochemical reactions on a semiconductor (e.g., TiO2) converted solar energy into electrochemical energy. When sun light strikes the TiO2 semiconductor, the photogenerated holes oxidized VO2+ into VO2
+ at the photoanode; meanwhile the photogenerated electrons reduced V3+ to V2+ at the at the counter electrode. The oxidized form of VO2
+ and reduced form of V2+ thus retain the chemical energy and can be converted to electricity via a reverse reaction (i.e., a discharge process); this process is similar to that in an all vanadium flow battery. [2]
Our preliminary results of photo charging indicated 95% faradic efficiency. This design could be a promising approach for efficient and regenerative solar energy storage. [3]
Reference:
[1] M.G. Walter, E.L. Warren, J.R. McKone, S.W. Boettcher, Q. Mi, E.A. Santori, N.S. Lewis, Solar water splitting cells, Chemical reviews, 110 (2010) 6446-6473.
[2] L. Li, S. Kim, W. Wang, Z. Yang, Advanced Redox Flow Batteries for Stationary Electrical Energy Storage, US Department of Energy, (2012).
[3] Z. Wei, D. Liu, C. Hsu, F. Liu, All-vanadium redox photoelectrochemical cell: An approach to store solar energy, Electrochemistry Communications, 45 (2014) 79-82.

Figure 1
Sn Thin Films and Their Application in Sodium Ion Battery
Authors: Xaba Nqobile , Modibedi Remegia Mmalewane , Mathe Mkhulu K. , Khotseng Lindiwe Eudora , Ozoemena Kenneth I. 
Published: February 2020

Secondary batteries provide a more convenient way of storing energy generated from solar or wind power plants. Lithium ion battery is the most developed battery system with applications in portable electronics and potentially electric vehicles. The increased applications of lithium ion batteries would impact the reserves of lithium and therefore increase the cost of lithium ion battery. In order to avoid this situation, an alternative to lithium ion battery needs to be developed. Sodium, as the fourth most abundant element on earth, can be used in applications where energy density is not critical instead of lithium based batteries due to its low cost. Moreover, the technology to develop sodium ion batteries (NIBs) is available due to similarities with lithium ion battery. The challenge to developing NIBs is finding a suitable low cost anode material. Thin films of Sn were prepared using electrochemical atomic layer deposition (EC-ALD) on Au slides, Cu foil and Ni foam substrate/current collectors to be used as anode material in sodium ion battery. The deposition parameters were optimized using cyclic voltammetry. The morphology, thickness and elemental mapping was done using FIB-SEM, AFM and SEM/EDS. Electrochemical tests were conducted using cyclic voltammetry and impedance spectroscopy. Charge and discharge tests were done to determine the best performing material.
Key words: Sn, EC-ALD, thin films, current collector, Sodium ion battery

References

[1] M. D. Slater, D. Kim, E. Lee, C. S. Johnson, Advanced Functional Material 23.8 (2013) 947-958.
[2] S. Y. Hong, Y. Kim, Y. Park, A. Choi, N.S. Choi, K. T. Lee, Energy & Environmental Science 6.7 (2013) 2067-2081.
[3] V. Palomares, P. Serras, I. Villaluenga, K. B. Hueso, J. Carretero-González, T. Rojo, Energy & Environmental Science 5.3 (2012) 5884-5901.
Development of highly durable Ni-MH batteries through introduction of highly conductive Co compound-coated Ni (OH) 2 technology
Authors: Shigekazu Yasuoka , Takuya Kai , Yuzo Imoto , Takeshi Ito , Takayuki Yano , Kazuta Takeno , Hirofumi Yanagawa , Shuichi Doi 
Published: February 2020

New L.S.D.(Low Self-Discharge)type Ni-MH batteries, such as eneloop Ni-MH batteries, were developed by introducing two major and original technological innovations. The first is a super-lattice hydrogen absorbing alloy technology, which results in higher capacity and longer cycle life. The second is HCN: highly conductive Co compound-coated Ni (OH) 2 technology, which results in higher capacity and higher durability. Even if HCN is charged and discharged in a cell, it maintains the same crystal structure as the raw material, Co valence differs from CoOOH which Co(OH)2 is clearly charged in the cell, it’s crystal structure is less apt to collapse and over-discharge characteristics are improved. By optimizing HCN manufacturing method, we succeeded in developing a more highly durable positive electrode and cell.

Figure 1
Highly Durable and Efficient Pore Filling Type Ion Exchange Membranes for Reverse Electrodialysis
Authors: Choi Young-Woo , Lee Mi-Soon , Kim Chan-Soo , Kim Han-Ki , Nahm KeeSuk 
Published: February 2020

Highly durable ion exchange pore filling membranes (cation exchange membranes and anion exchange membranes) with high ion transfer coefficients have been developed for reverse electrodialysis as an energy conversion system. The polymer electrolytes in both cases of cation exchangeable and anion exchangeable ones consisting of the whole hydrocarbon materials were introduced into porous hydrocarbon substrates and crosslinked by radical polymerization in this work. The thickness of the prepared pore filling membranes was controlled between 20 and 25 micrometers to extremely lower membrane resistance and to increase ion transfer. The prepared ion exchange pore filling membranes were characterized by using dimensional stability, membrane area resistance, ion transport number, and phisico-chemical stability. Also the thermal and the structural properties of the prepared membranes were determined. Meanwhile, all the properties of the prepared membranes were compared with commercial membranes obtained from Tokuyama, Fuji, and Fuma-Tech. Furthermore, RED cell performance and energy efficiency using the prepared pore filling membranes were also evaluated. Finallly we obtained a world best cell power density when comparing to the result reported in elsewhere.
Optical Studies of Dry and Wet Reformed Methane on Solid Oxide Fuel Cell Anodes
Authors: Qadri Syed Noorullah , Kirtley John D. , Steinhurst Daniel A , Walker Robert A , Pomfret Michael B , Owrutsky Jeffrey C 
Published: February 2020

The presently limited understanding of solid oxide fuel cell (SOFC) anode mechanisms is due to a lack of experimental techniques that can probe species and component materials directly during operation, or in operando. Previous investigations on the efficiency of Ni-YSZ-based electrode materials in different reforming conditions have been performed using post-mortem and in situ electrochemical analyses with little information on specific mechanisms that lead to fuel oxidation and cell degradation. An ensemble of non-invasive optical methods consisting of near infrared thermal imaging (NIRTI), Raman spectroscopy, and Fourier-transform infrared emission spectroscopy (FTIRES) is utilized to correlate the chemistry of fuel oxidation and carbon formation with traditional electrochemical measurements for methane and simulated biogas fuels in operating SOFCs.
Different reforming conditions for methane including plain, wet (steam), and dry (carbon dioxide) are investigated on anode- and electrolyte-supported cells. NIRTI results demonstrate that cooling on the anode surface due to endothermic hydrocarbon cracking for dry reforming or simulated biogas is significantly greater than for unreformed methane on both types of cells. Raman and FTIRES both show that more carbon is deposited with methane than with biogas. The small amount of carbon formed is limited to lower temperatures with simulated biogas whereas carbon formation occurs to a great extent at all temperatures with methane. Exhaust gas analysis with ex situ FTIR absorption measurements and mass spectrometry are combined with in operando measurements to further characterize and quantify the species involved. These findings serve as benchmark data for a better understanding of the mechanisms responsible for performance and degradation of SOFCs.
Novel Aluminum Air Ionic Liquid Based Battery
Authors: Gelman Danny , Shvartsev Boris , Ein-Eli Yair 
Published: February 2020

The changing and expanding needs in the energy market, ranging from power grid energy storage systems to portable power sources, dictates the development of efficient, inexpensive, and high performance battery systems. These advanced electrochemical systems should better deal with the challenges posed by the nascent green economy and non-oil based transport systems. One of the promising avenues for achieving these goals is the development of battery systems based on aluminum (Al) and its alloys as anodes. The main advantages of such systems are the low equivalent weight of Al, its high natural abundance in the earth’s crust, (leading to a rather low price), and its safety characteristics. In addition, Al and its by-products are non-toxic and environmental friendly. Aluminum battery systems cover a wide range of applications; from field-portable emergency power supply to remote power applications and batteries for transportation. Theoretically Al contains approximately one-half the energy content of gasoline per unit weight (8,100 Wh/kg for Al-air and 13,000 Wh/kg for gasoline) and three times the energy per unit volume (21,870 Wh/l for Al-air and 9,700 Wh/l for gasoline). Currently, the best practical utilization of gasoline for automotive applications can reach approximately 1,700 Wh/Kg and for aqueous Al-air batteries the values are 300-500 Wh/Kg. Nevertheless, the utilization of Al-air batteries as a sustainable energy storage device is hampered by some severe problems. High corrosion rate of the Al anode in aqueous alkaline solution is of great concern in terms of Al utilization and safety. On the other hand, Al surface activation is somewhat problematic in non-aqueous electrolytes, limiting substantially the possibility to utilize any power output. In this study, a newly developed non-aqueous Al-air battery is presented. The battery configuration utilizes 1-ethyl-3-methylimidazolium oligo-fluoro-hydrogenate (EMIm(HF)2.3F) room temperature ionic liquid (RTIL). The battery shows the ability to sustain current densities up to 1.5 mA/cm2, producing a capacity of 140 mAh/cm2 and thus, utilizing above 70% of the theoretical Al capacity. This is equivalent to an outstanding energy densities of 2,300 Wh/Kg and 6,200 Wh/L. Al2O3is detected at the air electrode as the battery discharge product, being the main cathodic reaction of oxygen reduction coupled with Al ions migrated to the air electrode.

* Equally contributed to the presented study

Figure 1
Modelling of Radical Reactions at Platinum Deposits in Polymer Electrolyte Membranes
Authors: Eslamibidgoli Mohammad J. , Eikerling Michael 
Published: February 2020

Hydroxyl radicals are the leading cause of chemical degradation observed in polymer electrolyte membranes (PEM). Recent experimental studies have shown that Pt nano-deposits in the PEM (PITM), which originate from Pt dissolution in the catalyst layer, could play a dual role in radical-initiated membrane degradation [1]. Surface reactions at Pt particles could facilitate the formation as well as the scavenging of radicals. The net effect of Pt surface processes on the radical balance depends on the local equilibrium conditions around the Pt nano-deposits, specifically, their equivalent local electrode potential [2]. In this presentation, we will first discuss the potential distribution at PITM as a function of externally controlled thermodynamic conditions. Thereafter, we will present a Density Functional Theory investigation of the surface reactions at the Pt(111)|water interface that involve O2, H2O, H2O2 and OH radical species. We calculate the effective rates of radical production at PITM by incorporating the local conditions obtained in the above steps. The results are compared to experimental measurements of fluoride emission under varying pressure settings in Pt impregnated PEMs.

References:

[1] M. P. Rodgers et al., J. Electrochem. Soc.
160 (10) F1123-F1128 (2013)
[2] M. J. Eslamibidgoli et al., J. Phys. Chem. C. Submitted.