bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Voltage Electrolytes Based on Nitrile Containing Disiloxanes for Lithium-Ion Batteries
Authors: Pohl Benjamin , Bieker Peter , Winter Martin , Wiemhöfer Hans-Dieter 
Published: February 2020

Two nitrile containing disiloxanes were investigated as non-volatile solvent for electrochemically stable electrolytes suitable for high energy and high power density lithium-ion batteries. The investigated disiloxanes show an excellent thermal behaviour (bp = 106 °C, 0.1 mbar) with a very low glass transition temperature T
gdown to -107 °C.
Fig. 1 a) CV of TmdSx-PN and b) Arrhenius plot of nitrile containing disiloxane TmdSx-OPN with different LiTFSI salt concentrations.
Electrochemical characterization was performed by temperature dependent impedance spectroscopy, differential scanning calorimetry, cyclic voltammetry and constant current cycling. The siloxane electrolytes showed a wide electrochemical window up to 5.4 V vs. Li/Li+ using LiTFSI as lithium salt. High ionic conductivity was found up to 1 mS∙cm-1 at 30 °C and a molality of 0.7 mol/Kg (CN:Li = 11:1).[1] These are the highest reported ionic conductivities and anodic stability for a liquid siloxane electrolyte.[2] Charge-discharge half-cell test were done with LiFePO4cathode materials. These results show that nitrile functionalized disiloxanes are very promising electrolyte solvents for the use in lithium-ion batteries with high energy densities. In addition, nitrile functionalized disiloxanes are very suitable as liquid solvent in polymer based gel electrolytes.
The authors acknowledge funding by the German federal ministry of education and research (BMBF) within the project “MEET Hi-EnD”.
[1] B. Pohl, M.M. Hiller, S.M. Seidel, M. Grünebaum, H.-D. Wiemhöfer, submitted, (2014).
[2] S. Jeschke, A.-C. Gentschev, H.-D. Wiemhöfer, Chem. Commun., 49 (2013) 1190-1192.
Intercalation Induced Stress Effects of the Core-Shell Anode Materials for Lithium Ion Battery
Authors: Gwak Yunki , Moon Janghyuk , Chang Seongmin , Cho Kyeongjae , Cho Maenghyo 
Published: February 2020

Rechargeable lithium-ion batteries are widely used as electric power for portable electronics and electric vehicle due to its excellent characteristics such as high voltage, and high energy density.
Silicon is a promising anode material for high performance lithium ion batteries, as it has very high theoretical reversible specific capacity (3579 mAh/g for Li15Si4) at room temperature. However, implementation of silicon-based materials has some challenges. Active particle pulverization caused by the large volume expansion leads to the loss of electrical contacts at the electrode. It is recognized as one of the major capacity fade with repeated charges–discharge cycling. Various experimental studies have been attempted to overcome this mechanical degradation using fabrication of nano-sized structures, porous materials and core-shell structures.
Especially, core–shell structure exhibits improved physical and chemical properties : suppressing large volume expansion resulting in inner core fracture, preventing the inner core from forming excessive SEI and enhanced electrical conductivity.
Experimental results have already provided a core-shell structure capability for LIBs. However, the analysis of core-shell structure using model simulation is not well explored to support experimental results.
Therefore, we propose a model of the intercalation-induced stresses for core-shell particles with various morphologies and deal with stress effects on Lithium ion diffusion in active particles. The radial compressive stress at the core-shell interface mitigates the crack growth of active core materials and this radial stress eventually enhances the cycling performance of LIBs. However, this compressive stress influences on the lithium ion diffusion and affects the electrochemical behavior over their single-component counterpart. So, we suggest the desirable range of shell thickness and allowable shapes of core-shell structure.

ACKNOWLEDGEMENT

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2012R1A3A2048841) and by the Industrial Strategic technology development program (10041589) funded by the Ministry of Knowledge Economy (MKE, Korea)
Multiscale Analysis of Lithiation of Si Anode of Li-Ion Batteries: First Principle Calculation and Finite Element Analysis
Authors: Moon Janghyuk , Chang Seongmin , Gwak Yunki , Cho Kyeongjae , Cho Maenghyo 
Published: February 2020

Silicon is known to have large Li storage capacity up to 4.4 Li atoms per Si atom in Li22Si5 compounds, but the large volume change and the mechanical stress during the charge-discharge cycles have damaged the electrode structures leading to rapid capacity fade.
Recently, Cui et al. have applied the silicon nanowire structures to avoid the mechanical stresses induced by the volume change and demonstrated promising capacity of the silicon nanowire anode for Li ion batteries. However, there are many issues on the lithiation in silicon anode to understand its physics of mechanism.
The kinetics of Li diffusion in Si anode is a main issue because the mechanical failure of Si active material significantly affects the stress state during cycles. In this presentation, we analyze the Li diffusivity in bulk-Si and LixSi (x>1) systems using first principle calculation and obtain the Li diffusion coefficient as function of Li concentration using kinetic Monte Carlo simulation. We also study the difference of lithiation between crystalline silicon and amorphous silicon.
Based on the first principle calculation, we check the mechanical stability of Si anode in various shape and charged condition using the diffusion-induced macroscopic model based on finite element method. Our multiscale analysis can provide reliable predictions on the stability with respect to the stress deviation according to size and shape of Si nanowire including charge rates. We also construct a non-dimensional design criteria equation for allowable stresses based on Buckingham-Pi theorem. Moreover, we analyze stress of more complex Si nanowire called Si nanotube and explain why pre-lithiated Si nanowire could have better cycle-ability compared to pristine one.
The multiscale approaches of Si anode from atomic scale to continuum scales help understand the mechanical failure of the Si anode in terms of the microstructure variations, and suggest a guideline to improve the Si anode performance for LIBs.

ACKNOWLEDGEMENT

This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2012R1A3A2048841) and by the Industrial Strategic technology development program (10041589) funded by the Ministry of Knowledge Economy (MKE, Korea)
Lithiation of Silicon Electrodes Investigated by In-Operando Neutron Reflectometry
Authors: Jerliu Bujar , Hüger Erwin , Seidlhofer Beatrix Kamelia , Steitz Roland , Schmidt Harald 
Published: February 2020

Kinetic processes and interface phenomena at electrodes during charging and discharging cycles play a key role for optimization of lithium-ion batteries (e.g. for charging times and power density). In order to study lithium insertion/de-insertion into electrodes and the underlying mechanisms, we applied neutron reflectometry as a non-destructive analysis technique. This method allows to study lithiation in-operando during cell operation. As negative electrode material, silicon is used a promising candidate for future Li-ion battery applications due to its high theoretical specific capacity of about 4 Ah/g.
The experiments are done using a three electrode electrochemical cell setup with a layered nanometer-sized amorphous silicon anode. The working electrode is deposited by magnetron sputtering on a quartz block covered by a current collector. Counter and reference electrode are made of pure lithium. A liquid electrolyte is used together with a housing made of high density polyethylene.
The experiments allow to monitor the modification of Li content and the corresponding volume expansion/contraction of the electrode during lithiation on the nanometer scale. The measurements indicate that during galvanostatic charging Li incorporation takes place in form of a process, where a moving LixSi phase boundary plays an important role. Possible lithiation mechanisms are discussed. Neutron reflectometry measurements during cyclic voltammetry allow to identify regions (U/I characteristics) where considerable lithium incorporation takes place and where not. For comparison, experiments on the lithiation of massive crystalline silicon blocks are shown.
B. Jerliu et al. Phys. Chem. Chem. Phys., 15, 7777, (2013)
Lithium Phosphorous Sulfurous Oxynitride (LiPSON) as a New Solid Electrolyte Material for Application in Thin-Film Batteries and Electrochromic Devices
Authors: Su Yurong , Falgenhauer Jane Christine , Polity Angelika , Meyer Bruno K. , Geiss Matthias , Leichtweiss Thomas , Janek Jürgen 
Published: February 2020

Compared to lithium ion batteries of current generation which contain liquid or gel-electrolytes with aprotic solvents, all-solid-state batteries promise long lifetime, high volumetric energy density and inherent safety. Current battery research therefore focuses on the search for stable and incombustible inorganic solid electrolytes with high lithium ion conductivity, negligible electronic conductivity and chemical stability in contact with the electrodes – particularly towards the metallic Li anode. For the application in thin-film batteries glassy lithium phosphorous oxynitride electrolyte (LiPON) has become the state-of-the-art material due to its superior chemical stability. Commercial cells comprising LiPON are already available. Being an insulator with a high optical bandgap, LiPON may be also well suited as electrolyte in electrochromic thin film devices.
However, LiPON has a relatively poor ionic conductivity (< 1 x 10-6 S cm-1) and needs to be applied as a very thin film in order to obtain sufficient current densities in a cell rendering pin-hole free large-area deposition a major technological challenge. New materials with higher conductivities would be highly desirable.
Here, we report for the first time on the successful deposition of lithium phosphorous sulfurous oxynitride (LiPSON) thin films by RF magnetron sputtering from a mixed Li3PO4 and Li2SO4 target in reactive nitrogen atmosphere. The electrical properties (ionic and electronic partial conductivities) of the films have been characterized by electrochemical impedance spectroscopy (EIS) and DC polarization techniques. Ionic conductivities as high as 6 x 10-6 S cm-1 (Ea= 0.47 eV) are achieved. Moreover, we succeeded also in preparing pure LiPON films with extraordinary high ionic conductivities and high deposition rates. Our detailed analysis of the films includes the characterization of compositions by energy-dispersive X-ray spectroscopy (EDX) and by inductively coupled plasma optical emission spectrometry (ICP-OES) as well as of chemical properties by photoelectron spectroscopy (XPS). In addition, we characterized the optical properties of the films by UV-VIS spectroscopy.
Finally, we will present first results of the electrical properties of cathode/LiPSON half-cells.
A Thermodynamically Consistent Model for Electric Double Layers in Li All-Solid-State Batteries
Authors: Braun Stefanie , Latz Arnulf , Yada Chihiro 
Published: February 2020

Due to their expected improved safety properties, Li all-solid-state batteries provide an attractive alternative to conventional battery systems. However, as yet their performance is strongly limited, since the relevant transport restrictions in the solid electrolyte are still not sufficiently understood. Of great importance in this context are space charge regions at the boundaries between active particles and the electrolyte, similar to the electric double layers in liquid electrolytes. Gaining knowledge about the behavior of this region and the factors that influence it will be a significant step towards a better understanding of the transport properties of a solid electrolyte.
In this work, we propose a new, mathematically rigorous model for a Li solid electrolyte. Whereas literature on the modeling of liquid electrolytes is abundantly available, the situation is very different for solid electrolytes. The number of theoretical treatments on this topic is very limited [1], and existing work does not always treat transport and equilibrium properties consistently. We overcome this problem by carefully developing a thermodynamically fully consistent model on the basis of first principles only, using the method of rational thermodynamics. To this end, the laws of continuum mechanics are supplemented by constitutive equations, which can be derived from a free-energy functional that describes the properties of the system on the macroscopic scale (i.e., beyond ~10 interatomic distances). An important step is to identify the proper free-energy functional for the solid electrolyte. Basing our theory on a functional that describes Li ion hopping on a fixed anion lattice containing defects, we analyze the charge and potential distributions in a solid electrolyte in contact with a metal electrode under the influence of varying electrode potential differences. The resulting differential equations are solved numerically as well as analytically in the limit of small electrode potential differences.
References:
[1] M. Landstorfer et al, Phys. Chem. Chem. Phys.
13, 12817-12825 (2011).
Comparative Study on Experiment and Simulation of Blended Active Cathode Material for Lithium Ion Batteries Using COMSOLTM Multiphysics 4.3b
Authors: Appiah Williams Agyei , Khue Luu Van , Lee Yunju , Choi Jaecheol , Ryou Mhyung-Hyun , Lee Yong Min 
Published: February 2020

It is important to understand the electrochemical performance as well as the influence of various cathode materials; LiMn2O4 and Li[Ni0.6Co0.2Mn0.2]O2, on each other when mixed together as a single positive electrode for lithium ion batteries. In view of this, we used a previously developed lithium ion mathematical model for treating multiple active material to examine the electrochemical characteristics of the blended LiMn2O4 and Li[Ni0.6Co0.2Mn0.2]O2 active materials. The simulated results obtained using COMSOL multiphysics 4.3b were compared to the experimental results from coin cells built with the two positive electrode materials (composition based on LiMn2O4 and Li[Ni0.6Co0.2Mn0.2]O2) mixed in three different ratios and graphite as the negative electrode material. We also modeled the capacity fade effects on LiMn2O4 graphite cell based on the SEI formation at the negative electrode material and the particle dissolution of LiMn2O4 simultaneously to account for the behavior of the cell.
There is a good agreement between the simulated results and the experimental results with slight deviations at higher C-rates. We observed from our experiment that, at high powers, the specific energy obtained from the electrode made of only LiMn2O4 exceeds that obtained from the electrode made of only Li[Ni0.6Co0.2Mn0.2]O2 but the specific energy of Li[Ni0.6Co0.2Mn0.2]O2 also exceeds that of LiMn2O4 at low powers. It was also observed that, the initial discharge capacity of LiMn2O4 is greatly enhanced due to the presence of the Li[Ni0.6Co0.2Mn0.2]O2 but its cycle ability was drastically reduced while that of the Li[Ni0.6Co0.2Mn0.2]O2 was improved impressively.

References

[1] P. Albertus, J. Christensen J. Newman, J. Electrochemical Society, 156 (7) (2009) A606-A618
[2] Jorge Vazquez-Arenas, Michael Fowler, Xiaofeng Mao, Shih-ken Chen, Journal of Power Sources
, 215 (2012) 28-35
New Flame Retardant Composite Separators Based on Metal Hydroxide for Lithium-Ion Batteries (LIBs)
Authors: Yeon Daeyong , Lee Yunju , Yeon Subin , Jeong Jiseon , Ryou Mhyung-Hyun , Lee Yong Min 
Published: February 2020

From the viewpoint of lithium-ion battery safety, the separator has been considered as a key component, because its primary function is to prevent internal short-circuit between the cathode and the anode. In general, separators in lithium-ion batteries (LIBs) are made mostly of polyolefin, predominantly polyethylene (PE) or polypropylene (PP). These polyolefin-based separators are widely used and offer many advantages but exhibits poor thermal stability at high temperature, and thus result thermal runaway threatening safety issue of LIBs. To improve thermal properties of LIBs, many researches have been reported using ceramic nanoparticles (Al2O3 and SiO2) coated separators.
Along with this line, in this study, as a new approach to exciting the thermal stability of a separator, we developed a new composite separator. We tried to improve the thermal stability and flame retardancy of a microporous polyethylene (PE) membrane by coating both sides of the membrane with nano-sized metal hydroxide (Al(OH)3 and Mg(OH)2) ceramic powders and poly(vinylidene fluoride-co-hexafluoropropylene) PVdF-HFP binder. The composite separator exhibited equivalent thermal stability compared to metal oxide ceramic-coated separator and flame retardancy for combustion condition. Also, Using these composite separator, we assembled lithium-ion cells composed of a graphite anode and a LiCoO2 cathode, and showed their electrochemical performances compared to those employing oxide (Al2O3 and SiO2) ceramic-coated separators.

Reference

[1] J.-K. Park, M.-H. Ryou, G.-B. Han, J.-N. Lee, D.J. Lee, J. Song, J.Y. Lee, South Korea. Patent, 10-1122159, 2012
[2] Y. Lee, M.-H. Ryou, M. Seo, J.W. Choi, Y.M. Lee, Electrochimica Acta 113 (2013) 433– 438

Acknowledgement

This research was financially supported by the Basic Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0025738).
High Performance Lithium-Ion Polymer Cells Assembled with Composite Gel Polymer Electrolytes Based on Core-Shell Structured SiO2(Li+) Nanoparticles
Authors: Park Se-Mi , Kim Dong-Won 
Published: February 2020

Gel polymer electrolytes have been considered as one of the most promising electrolyte materials for rechargeable lithium batteries. However, the host polymers lose mechanical strength when plasticized by organic solvents. In order to obtain the gel polymer electrolytes with improved electrical and mechanical properties, inorganic fillers such as SiO2, Al2O3, TiO2 and BaTiO3 have been incorporated into host polymers [1,2]. The addition of inorganic fillers improves ionic conductivity of polymer electrolytes and interfacial properties. In these composite gel polymer electrolytes, the inorganic particles promote electrochemical properties of the polymer electrolytes through physical actions without directly contributing to the lithium ion transport process. It is of our interest to synthesize and introduce inorganic materials containing dissociative lithium ions [3]. In this study, we prepared the composite gel polymer electrolytes based on core-shell structured SiO2 nanoparticles containing a lot of lithium ions which can also act as the source of charge carriers. The composite gel polymer electrolyte exhibited high ionic conductivity, high Li+transport number, good mechanical strength to prepare thin films (~25 μm) and favorable interfacial characteristics. Lithium-ion polymer cells assembled with the composite gel polymer electrolytes were characterized by high capacity and good capacity retention at high temperature as well as ambient temperature.

[References]

[1] F. Croce, G.B. Appetecchi, L. Persi, B. Scrosati, Nature 394 (1998) 456.
[2] S.K. Das, S.S. Mandal, A.J. Bhattacharyya, Energy Environ.Sci. 4 (2011) 1391.
[3] Y.S. Lee, S.H. Ju, J.H. Kim, S.S. Hwang, J.M. Choi, Y.K. Sun, H. Kim, B. Scrosati, D.W. Kim, Electrochem. Commun. 17 (2012) 18.
Real Time Observation of LiFePO4:V Cathode and (Ti,Sn)O2 Anode for a Lithium Ion Battery By Synchrotron X-Ray and Neutron Methods
Authors: Su HuiChia , Hu Chih-Wei , Chang Chia-Chin 
Published: February 2020

Real time observations on a lithium ion battery containing (Sn,Ti)O2 anode and LiFePO4:V cathode are performed by in situ synchrotron X-ray and neutron methods. To meet the requirements of real applications to the electric vehicles, storage devices,...etc., the new electrode materials exploration and current materials modification are very important to achieve such a goal. In situ techniques could provide real time structural changes during charging and discharging. Whether working on new material exploration or current materials modification, the obtained information from structural changes could provide a correct direction to develop a more suitable battery for real applications.
(Sn, Ti)O2 is newly developed [1] for next general anode material. To combine the good characteristics of TiO2 and high specific capacity of SnO2, we could have a good and interesting material. The synthesized (Sn,Ti)O2 is rutile-type solid solution after annealing. We have chosen the sample after annealing under 550°C, which has the best electrochemical properties to be the anode material. From the neutron and X-ray powder diffraction (XPD) patterns, we are certainly sure the formation of (Sn,Ti)O2 with a part of amorphous components in the produced samples. The in situ XPD will provide more detail structural changes during the electro-chemical cycling. From X-ray absorption data, we find the extended X-ray absorption find structure (EXAFS) spectra of Sn are changed but no changes of Ti spectra as the annealing temperatures changes. That means Si-O-Ti bindings formed. From the in-situ measurement of Sn EXAFS curves, these spectra won’t be changed according to the changes of charging and discharging conditions. That means the local environment of Sn didn’t changed. That fits to expect on that Ti plays the most important role during lithiation and delithiation process. In situ EXAFS spectra of Ti will prove this assumption.
LiFePO4:V cathode is produced by modifying the pristine LiFePO4 by adding a small amount of V. After adding V into LiFePO4, the mechanism of enhancing the capacity of the LiFePO4 cathodes is due to the location of V is at the lithium site and then to induce lithium vacancies in the crystal structure [2]. From the in situ X-ray data, whether in XPD or X-ray absorption near edge structure (XANES), which reveals the parts of amorphous components of the pristine LiFePO4, are increased as the electrochemical cycles increase. After adding V, the speed to form the amorphous parts is reduced. As the increase of the amorphous part, the electrochemical properties become poor. That means the added V could effectively prolong the cycling life through reducing production of amorphous components. To observe the (Sn, Ti)O2 anode and LiFePO4:V cathode in a battery at the same time is worth expect.
References:
[1] Y. C. Chen et al., Nanoscale 5 (2013) 2254.
[2] C. Y. Chiang et al., J. Phys. Chem. C 116 (2012) 24424.