bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Type of Reference Electrode for Three-Electrode Setups: Choice of Material and Geometry
Authors: Costard Janina , Ender Moses , Illig Jörg , Weiss Michael , Ivers-Tiffée Ellen 
Published: February 2020

Electrochemical Impedance Spectroscopy (EIS) is highly supportive for analyzing electrode processes in lithium-ion cells. Commonly, a three-electrode setup is used, with a lithium metal counter electrode and/or a lithium metal point-like reference electrode. But its usability is restricted, as lithium metal as a counter electrode often dominates the impedance response, and in general, causes a stochastic component in the EIS data. Furthermore, a point-like lithium metal reference electrode may cause errors such as quantitative factors, cross contaminations and inductive artifacts, as shown by experiment and FEM-simulation [1]. Therefore, material choice and geometric arrangement of a reference electrode seems crucial for obtaining reliable, reproducible and long-term stable measurements.
Li4Ti5O12 (LTO) was already proposed in literature as a most promising candidate, showing a stable potential plateau at 1.55 V versus lithium, because of a two-phase equilibrium [2]. This study compares LTO versus lithium metal and examines various geometries for reference electrodes by EIS measurements and FEM-simulations.
Our results recommend a reference electrode in a mesh-type design, centered between two separators, as most reliable in terms of symmetry. Furthermore, an aluminum mesh slurry coated by fine LTO particles delivered a stable potential over more than hundred hours, as proven by potential measurements.
Finally, the suitability of this new type of reference electrode is validated for electrochemical impedance spectroscopy and C-rate tests.

References

[1] M. Ender, A. Weber, E. Ivers-Tiffée, Journal of the Electrochemical Society, 159 (2012), A128-A136
[2] F. La Mantia, C.D. Wessells, H.D. Deshazer, Y. Cui, Electrochemistry Communication, 31 (2013), 141-144
Thermofluids Analysis of the Coolant Flow during Lithium-Ion Battery Operation
Authors: Serincan Mustafa Fazil , Tabatabaei Malazi Mahdi 
Published: February 2020

Thermal management of lithium ion battery packs has been accepted as one of the most critical application considerations amid the bad publicity suffered from the battery fires in the electric vehicles and airliners. Removal of the heat generated during lithium battery operation at high charge and discharge rates and rapid load changes is at paramount importance to restrain temperature rises. Forced air-cooling and liquid cooling via channels between cell pairs are frequently used in the designs of battery packs used in commercial applications.
In this study, liquid water-cooling of lithium ion battery packs is analyzed with a multiphysics computational fluid dynamics (CFD) model and a channel geometry is proposed to increase heat removal rates. The three dimensional CFD model geometry consists of two prismatic lithium polymer cells sandwiching a plate with the cooling channels grooved inside. Geometrical and electrochemical parameters of a 40 Ah commercial lithium polymer battery are used in the model. Non-isothermal electrochemical model of the lithium ion battery incorporates energy, charge and species balances in the solid and electrolyte phases with the electrochemical kinetics represented via Butler-Volmer equations. Effects of porous media on the energy, charge and species transport are taken into consideration. Electrochemical battery model is coupled with the flow model developed in the cooling channels. Non-isothermal momentum equation and the energy equation are solved in the cooling channels to account for the thermofluids phenomena.
Channel geometry is initially selected based on logarithmic mean temperature (LMTD) difference method. CFD model is developed based on the characteristic dimensions and the flowrate determined from the LMTD study. In the course of simulations shape and dimensions of the channel are further tuned to achieve a design enhancing heat transfer rates during the operation of the lithium ion battery.
Steady state simulations are carried out to investigate thermal management of the lithium ion battery during typical modes of operation. Temperature gradients and charge distribution inside the battery geometry are identified for different current densities drawn from the battery. A parametric analysis involving different discharge rates up to 8C is conducted. Temperature distribution at each discharge rate is obtained to estimate the possible locations of the spikes during the battery operation. Moreover, thermo-electrochemical behavior of the cell is studied at charging conditions. Charging rates beyond manufacturer recommended maximum of 2C are analyzed to estimate the accompanied rise of cell temperatures in the case of fast charging applications. Model results are exploited as preliminary design recommendations for a more inclusive thermal management system.
In Situ Fabrication of 3-Dimentional Li4Ti5O12/Reduced Graphene Oxide Microspheres with High Tap Density for High-Rate Lithium Ion Batteries
Authors: Kim Myeongseong , Lee Suk Woo , Kim Kwang-Bum 
Published: February 2020

Spinel Li4Ti5O12 has attracted much attention as an anode material for lithium-ion batteries because of its good Li-ion intercalation reversibility and extremely small structural changes during charge-discharge cycling. Despite these advantages, Li4Ti5O12 is not suitable for commercial use due to its low electronic conductivity (10-13 S cm-1), which leads to poor rate capabiltiy.1 Several effective ways to improve the rate capability of Li4Ti5O12 have been reported, including reduction of the particle size to the nanoscale, doping Li, Ti, or O sites with small amounts of metal or nonmetal ions, surface modification or carbon coating, and its incorporation into composites with carbonaceous materials.2-4

Among the various carbonaceous materials, reduced graphene oxide (RGO) or graphene nanosheets has attracted considerable interest as electrode materials for electrochemical energy storage because of their unique properties such as high electronic conductivity, large surface area, and good mechanical properties. Some recent studies have demonstrated the excellent rate capability and cycle stability of Li4Ti5O12/RGO nanocomposites.4 However, in all these reports, the lithium–titanium–oxide (Li–Ti–O)/RGO nanocomposite as the precursor for Li4Ti5O12, was initially synthesized using a two-step or multistep process. In such multistep methods, Li4Ti5O12 particles can be limited the available sizes and morphologies. In addition, it is difficult to fabricate the phase-pure Li4Ti5O12 due to the formation of titanates with several other phases.5

Previously reported Li4Ti5O12/RGO nanocomposites mostly have 2-dimension morphologies with low tap density.4,5 The 2-dimentional Li4Ti5O12/RGO nanocomposites are not suitable for commercial use because their low tap density limits the volumetric energy density. Therefore, a simple and facile synthesis of 3-dimentional Li4Ti5O12/RGO nanocomposites with a high tap density and superior rate capability is highly desirable.
In this study, we report in-situ synthesis of 3-dimentional Li4Ti5O12/RGO microspheres with high tap density, wherein the initial Li-Ti-O/RGO precursor is fabricated by the spray drying method in the presence of all precursors in a solution. Upon subsequent heat treatment, phase-pure 3-dimentional Li4Ti5O12/RGO microspheres with high tap density were successfully synthesized. More detailed on the synthetic procedure, morpology, electrochemical and structural properties of 3-dimentional Li4Ti5O12/RGO microspheres will be presented at the meeting.
References

1. S. G. Doo et al, J. Am. Chem. Soc., 2008, 130, 14930.
2. N. Ohta et al, Adv. Mater., 2006, 18, 2226.
3. N. Jayaprakash et al, Appl. Nanosci., 2011, 1, 7.
4. H. K. Kim et al, Electrochem. Commun., 2010, 12, 1768.
5. H. K. Kim et al, J. Mater. Chem. A, 2013, 1, 14849
Heterostructure of SnO2/TiO2 Nanotubes with Precise Wall Thickness Control As Anodes for Lithium Ion Battery
Authors: Lee Jubong , Kim Myungjun , Lee Seonhee , Seo Seongrok , Bae Changdeuck , Shin Hyunjung 
Published: February 2020

Devices of energy storage and conversion draw much attention recently, among the devices, secondary lithium-ion batteries for energy storage will play an increasingly important role. SnO2 as anode materials have attracted a lot of attention and are regarded as one of the most promising candidates for lithium-ion battery, with the theoretical reversible capacity of 782 mAhg-
1 and low enough discharge potential of 0.01V. Like to other alloy-type anode materials, its practical application has been impeded by the poor cycling performance owing to the pulverization and subsequent electrical disconnection of the electrode caused by extremely large volume change (about 300%) during the insertion and extraction processes of lithium ions. Li2O phases, produced by the reaction of SnO2 and lithium ions, are electrochemically inactive, which is the main reason for the large initial irreversible capacity. To overcome this problem, feasible strategy is to design the nanostructure. 1-dimensional nanotubular structures exhibit enhanced cyclability due to the short diffusion path of lithium ions within the wall of nanotubes and the local empty space in the core of tubular structures can accommodate its volume expansion. SnO2 and TiO2 nanotubes as well as their heterostructures were synthesized by anodic aluminum oxide (AAO) template-directed ALD (Atomic Layer Deposition) process. Nanotubes and their heterostructures were characterized by thermogravimetric/differential thermal analysis (TG/DTA), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray diffraction (XRD).
The wall thickness of nonotubes can be easily controlled by the number of cycles during ALD processes. The porous nanotubes and their heterostructures exhibit high lithium ion storage capacity, fairly high rate performance, and high cyclability when evaluated as anode materials. As expected, the nanotubes of SnO2 with the wall thickness of about 10 nm show the initial capacity of 900 mAhg-1 and reduces down to 300 mAhg-1 after 50 cycle. The conversion reaction of SnO2 to Sn and further Li and Sn alloys were clealy observed by ex sity TEM. Composite heterostructures of TiO2/SnO2
show much improved cycle performance without any degradation during Li insertion and di-insertion. Advantages of using heterostructure of TiO2/SnO2
nanotubes as anode materials will be further discussed.

Figure 1
Enabling Aqueous Processing of Cathode Materials for Li-Ion Batteries
Authors: Laszczynski Nina , Kim Guk-Tae , Passerini Stefano 
Published: February 2020

Nowadays, Li-ion batteries have become the most promising power source for hybrid and electric vehicles. Considering their environmental friendliness, recycling issues and therefore cost issues, one approach towards greener batteries is the substitution of fluorinated binders like polyvinylidene difluoride (PVdF) that require the use of toxic and highly volatile solvents (e.g. N-methyl-2-pyrrolidone (NMP)), with aqueous binders such as sodium carboxymethyl cellulose (sodium CMC) [1]. Nevertheless, there is a significant drawback associated aqueous processing: slurries become strongly basic due to the reaction of the cathode material with water. This leads to aluminium corrosion of the current collector [2] in addition to the active material degradation.
One strategy to overcome material degradation and aluminium corrosion is the preliminary coating of the active material to prevent its reaction with water. It is then of paramount importance that the active material is not damaged upon coating process and the coating layer itself does not affect negatively the capacity or rate performance of the active material [3-5].
Here, the properties of coated Li-NMC are investigated using different coating approaches and materials. The coated Li-NMC materials were analysed by XRD to study their structure. The positive influence of the coating on the composite Li-NMC electrodes prepared with the aqueous binder is demonstrated, in particular with regard to the prevention of aluminium corrosion. SEM and TEM were used to characterize the composite electrodes, while elemental analysis and TGA were used to investigate the coating, quantitatively. Electrodes of coated and uncoated materials were prepared using the aqueous binder and investigated in terms of their capacity and rate performance to establish the influence of the active material coating.
[1] G.T. Kim, S.S. Jeong, M. Joost, E. Rocca, M. Winter, S. Passerini, A. Balducci, Journal of Power Sources, 196 (2011) 2187-2194.
[2] S.F. Lux, F. Schappacher, A. Balducci, S. Passerini, M. Winter, Journal of The Electrochemical Society, 157 (2010) A320-A325.
[3] M. Bettge, Y. Li, B. Sankaran, N.D. Rago, T. Spila, R.T. Haasch, I. Petrov, D.P. Abraham, Journal of Power Sources, 233 (2013) 346-357.
[4] B. Lin, Z. Wen, J. Han, X. Wu, Solid State Ionics, 179 (2008) 1750-1753.
[5] J. Ni, L. Gao, L. Lu, Journal of Power Sources, 221 (2013) 35-41.

Figure 1
Tri-Layered Si/CeO2/Polyaniline Composites As Anode Materials for Lithium-Ion Batteries
Authors: Bai Ying , Tang Yang , Wang Zhihui , Wu Chuan , Wu Feng , Liu Gao 
Published: February 2020

Si has very high theoretical specific capacity as an anode material in a lithium-ion battery. However, its application is seriously restricted because of relatively undesirable conductivity and poor cycling stability. Here we report Si/CeO2/Polyaniline (SCP) composite as an anode material, which was synthesized by hydrothermal reaction and chemical polymerization. The structures and morphologies of the SCP composites are characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). It is shown that Si/CeO2 (SC) particles are well coated by polyaniline (PANI) elastomer which has good electrical conductivity. The SCP shows larger reversible capacity and better cycling performance compared with pure Si. The first reason is that CeO2 can protect Si from reacting with electrolyte. More importantly, the PANI elastomer can accommodate the volume change of the composite during Li-alloying/dealloying processes, so the pulverization of silicon would be significantly reduced. The SCP material can retain a capacity nearly 775 mAh/g after 100 cycles, while pure Si only shows a capacity of 370mAh/g after 100 cycles.
Lithium Sulfide/Carbon (Li2S/C) Electrode Preparation in Hydrogen Sulfide (H2S) Flow and Its Electrochemical Performance
Authors: Dressel Carina B , Jha Himendra , Gasteiger Hubert A , Fässler Thomas F. 
Published: February 2020

Energy storage for automotive and portable devices is one of the main research topics today and in the future. Today’s batteries based on Li-ion technology are not up to par with the demands of long-range vehicles[1]. The solutions to this problem are beyond Li-ion technologies, e.g. Li/S or Li/air. Possible distances of >400 km or >550 km for Li/S or Li/air, respectively, compared to today’s 160 km with Li-ion technology are desirable[2]. The biggest obstacle in Li/S and Li/air batteries are safety concerns due to the use of elemental lithium as anode material[3]. This may be overcome by using a Li2S cathode, equivalent to the discharged state of the Li/S battery, and a lithium free anode such as carbon.
Since Li2S is very moisture sensitive, preparation of Li2S electrodes needs to be in a very controlled environment. We invented a new method to produce Li2S/C electrodes in a H2S flow, by using various lithium salts as starting materials. This way the air-sensitive Li2S is introduced in the electrode in the very last step. This lowers the process costs and allows an easier handling of the electrodes during preparation, since it is less moisture sensitive. Furthermore it might allow the use of aqueous binder systems which is novel for Li2S electrodes.
Electrodes containing a lithium salt, carbon and a binder were cast and after drying exposed to H2S. The resulting electrode consists of lithium sulfide, carbon and the binder. The reaction is confirmed by X-ray diffraction and elemental analysis. The morphology and homogeneity of the electrode is investigated by scanning electron microscopy. Galvanostatic cycling of the Li2S/C electrode validates the new method.
[1] X. Ji, L.F. Nazar, Advances in Li–S batteries, Journal of Materials Chemistry, 20 (2010) 9821.
[2] P.G. Bruce, S.A. Freunberger, L.J. Hardwick, J.M. Tarascon, Li-O2 and Li-S batteries with high energy storage, Nature materials, 11 (2012) 19-29.
[3] J.M. Tarascon, M. Armand, Issues and challenges facing rechargeable lithium batteries, Nature, 414 (2001) 359-367.
Separator-Free Hybrid Electrolytes Composed of Inorganic, Polymer and Liquid Electrolyte for Lithium-Ion Batteries with Enhanced Safety
Authors: Kim Seul-Ki , Jung Yun-Chae , Han Man-Seok , Shin Woo-Cheol , Ue Makoto , Kim Dong-Won 
Published: February 2020

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices and electric vehicles. However, safety issues still prevent full utilization of these batteries owing to the use of flammable liquid electrolytes, and safety problems have become a significant concern especially in large capacity applications such as electric vehicles and energy storage systems. In this respect, fabrication of solid-state lithium batteries by using inorganic solid electrolytes may give a fundamental solution for the safety issue of lithium batteries. However, sheet manufacturing, especially using thin-film technologies for making large-scale batteries, is considered to be difficult because of hard and brittle ceramic materials. In this work, flexible hybrid electrolytes composed of inorganic electrolyte with polymer binder and liquid electrolyte were prepared in the form of flexible film, and their electrochemical characteristics were investigated. An addition of small amount of liquid electrolyte significantly improved ionic conductivity and interfacial properties between electrodes and electrolyte. The optimized hybrid electrolyte was applied to the graphite/LiCoO2 pouch cells and their electrochemical performances were evaluated. The enhancement of battery safety was confirmed at the cell level by various techniques such as Accelerating Rate Calorimetry (ARC).
Evaluation of Flexible Li4Ti5O12 Anode Electrodes Using Water-Based Binder for Li-Ion Batteries
Authors: Lu Huiran , Behm Mårten , Cornell Ann , Leijonmarck Simon , Lindbergh Göran 
Published: February 2020

Li-ion batteries are today essential for portable electronic devices as a main power source. Flexible Li-ion batteries have attracted great attention and could be very useful in the emerging fields of flexible, wearable, implantable and bendable electronic devices. Nano-fibrillated cellulose (NFC), with a high aspect ratio (length/diameter) of the nanofibrils, has shown to be a promising binder material for flexible Li-ion batteries [i] [ii]. As a reinforcement component, it gives flexible electrodes good mechanical properties. In addition, the process of making the flexible electrodes is water-based, eliminating the toxicity problem of using conventional poly(vinylidene fluoride) (PVDF) as binder. However, capacity fading limits the stability of the flexible electrodes during repeated cycling. Side reactions on the graphite negative electrodes could be the reason for the capacity loss. Li4Ti5O12(LTO), with a high potential of 1.55 V versus Li metal, could be an alternative to graphite for flexible negative electrodes, reducing the reactivity with the electrolyte. In this work, the electrochemical performance, such as specific capacity and columbic efficiency (CE), and mechanical properties of flexible LTO anode electrodes using NFC as binder are investigated. Fig 1 shows the photograph of LTO electrode, illustrating the flexibility. Fig. 1 Photograph of flexible Li4Ti5O12
negative electrode.

[i] S.Leijonmarck, et al. Flexible nano-paper-based positive electrodes for Li-ion batteries-Preparation process and properties, Nano Energy, 2013, 2, 794–800.
[ii] S.Leijonmarck, et al. Single-paper flexible Li-ion battery cells through a paper-making process based on nano-fibrillated cellulose, Journal of Materials Chemistry A, 2013, 1, 4671-4677.

Figure 1
Lithium Metal Polymer Battery: Towards Optimized Cathodes and Crosslinked Polymer Electrolytes
Authors: Jeong Jiseon , Hoogil Lee , Choi Jaecheol , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

Although lithium metal polymer batteries (LMPBs) have lots of advantages such as high energy density, design flexibility and enhanced safety, they have not been widely used in the commercial market due to low ionic conductivity and poor interfacial stability towards electrodes comparing to liquid electrolytes. However, most of researches on LMPBs have been focused for electrolytes themselves without broad cell performance data such as cycle life and rate capability. Furthermore, as discovered in previous works on commercial LIBs, the electrode density and thickness are also very crucial parameters governing the electrochemical performance of batteries.
For the purpose of providing basic but essential electrochemical properties of LMPB, we have manufactured four different LiFePO4 cathodes with different densities and thicknesses. Their physical and electrochemical properties are investigated by using the unit cells consisting of LiFePO4/cross-linked polymer electrolyte/Li metal. In particular, with the optimized cathode and crosslinked polymer electrolyte, high capacity retention could be realized at even 5C and room temperature.

Acknowledgements

This research was financially supported by the Ministry of Education, Science and Technology (MEST) and National Research foundation (NRF) of Korea through the Human Resource Training Project for Regional Innovation (2014066977) and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2014046008).

Figure 1
Binder-Free Ceramic Coated Separators Prepared By Polydopamine Treatment and RF-Sputtering
Authors: Lee Taejoo , Lee Yunju , Yeon Daeyong , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

Most commercially available polyolefin separators are made of polyethylene (PE) and polypropylene (PP). Such separators have excellent mechanical strength, electrochemical stability and thermal shutdown properties, but their thermal properties are not sufficient to secure safety of large-format LIBs. As a result, most of separator manufacturers prefer to coat ceramic layer on at least one-side of the conventional polyolefin separators. However, this comes at an additional cost with the battery. Radio frequency (RF)-sputter process has been considered as an economically viable process to prepare ceramic separator coatings [1]. The major disadvantage associated with it is high operating temperature, which can give some thermal damage on polyolefin separator.
In this study, polydopamine is coated on a polyethylene separator which can improve the heat resistance of the polyethylene separators. Then using RF sputtering and Al2O3 targets, ceramic coatings are made on this separator. With a submicron polydopamine and ceramic coating layer, the coated polydopamine and Al2O3 (PDA) separator has sufficient thermal properties comparable to conventional ceramic coated separators. In addition, PDA separator is electrochemically evaluated by ion conductivity and uptake amount for wettability, impedance analysis, rate capability, and cycle life.

Acknowledgements

This research was financially supported by the Ministry of Education, Science and Technology (MEST) and National Research foundation (NRF) of Korea through the Human Resource Training Project for Regional Innovation (2014066977) and IT R&D program of MOTIE/KEIT (10046314).

References

[1] T. Lee, W. Kim, Y. Lee, M. Ryou, Y. Lee, Macromolecular Research, 22 (2014) 1190-1195