bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionic Shield for Polysulfides Toward High-Stable Lithium Sulfur Battery
Authors: Huang Jia-Qi , Zhang Qiang , Peng Hong-Jie , Wei Fei
Published: February 2020

Lithium sulfur batteries attract great attention due to their high energy density, while the real applications are still hindered by the rapid capacity degradation. Despite great effort devoted to solving the polysulfide shuttle between the cathode and anode electrodes, it remains as a serious challenge to build high-stable lithium sulfur battery, which related to the diffusion and reaction between polysulfides and the metal lithium anode.

We demonstrate a strategy of introducing an ion selective membrane to improve the stability and coulombic efficiency of lithium sulfur battery. Generally, porous polymer membrane serves as membranes in batteries to avoid the short circuit between anode and cathode electrodes. As indicated in Figure 1a, such routine membrane cannot stop the shuttle effect. Herein, we replace the routine membrane (Figure 1b) with an ion selective membrane, in which the sulfonate-ended perfluoroalkyl ether groups on the ionic separators are connected by pores or channels that are around several nanometers in sizes. These -SO3-- groups coated channels allow ion hopping of positive charge species (Li+) but reject hopping of negative ions, such as polysulfide anions (Sn
2-) in this specific case due to the coulombic interactions. Consequently, this cation permselective membrane acts as an electrostatic shield for polysulfide anions, and confines the polysulfides in the cathode side. An ultra-low decay rate of 0.08% per cycle is achieved within the initial 500 cycles for membrane developed in this work, which is less than half that of the routine membranes.

Such ion selective membrane is versatile for various electrodes and working conditions, which is promising for the construction of high performance batteries.

Reference

[1] Huang JQ, Zhang Q, et al. Ionic shield for polysulfides toward high-stable lithium sulfur battery.
Energy & Environ Sci.
doi: 10.1039/c3ee42223b.

Figure 1. Schematic of the different lithium sulfur battery configurations. (a) Cell with routine membranes, in which polysulfides shuttle between cathode and anode side. (b) Cell with ion selective membranes, in which polysulfide anions are limited in the cathode side. (c) Enlarged schematic showing the cation permselective membrane allows the transport of lithium cations and blocks the polysulfide anions.
Efficient Synthesis of Hierarchical Porous Carbons for Application in Li-S Cells
Authors: Strubel Patrick , Thieme Sören , Brückner Jan , Althues Holger , Kaskel Stefan
Published: February 2020

One of the most promising future generation candidates for safe, low-cost and long-lasting high energy density rechargeable energy storage systems is without any doubt the lithium-sulfur battery. However, despite more than two decades of intensive scientific research focusing on all cell components the commercialization of a viable lithium-sulfur battery has not been realized so far due to several challenges coupled with the electrochemical conversion of sulfur. One of the major drawbacks is the repeated dissolution and deposition of highly insulating sulfur compounds during cycling, which is furthermore accompanied by an extensive expansion and shrinking of the active material. A nanostructured conductive matrix is required. Porous carbons has been considered as one of the most promising conductive host structure, due to their low weight, high conductivity as well as adjustable properties (specific surface area, pore size, pore volume). In particular, suitable and especially effective production processes need to be established.

To overcome the existing drawbacks we focus on the development of a scalable and efficient approach for the synthesis of nanostructured porous carbon materials with pore properties specially tuned for an application in high capacity Li-S batteries. The large benefit of the process presented here is the removal of all pore building components by simply pyrolysing the MOx/carbon composite without any need for toxic/reactive gases and, moreover, purification of the as-prepared porous carbon. The obtained material provides not only good electrical conductivity but also high internal porosity (total pore volume up to 3.8 cm³/g) as well as a large number of electrochemical reaction sites due to its high internal surface area (up to 3000 m2/g). Applied in the Li-S cell, the porous carbon/sulfur composite exhibits a stable capacity of > 1000 mAh g-1-sulfur (> 600 mAh g-1-electrode) over 60 cycles at a high sulfur loading of 3.5 mg cm-2. Both high sulfur utilization and reversible transformation are attributable to the tuned properties of the carbon matrix.
Ionic Liquid-Based Electrolyte for Lithium-Air Battery
Authors: Knipping Etienne , Aucher Christophe , Martinez Crespiera Sandra , Amantia David , Aubouy Laurent
Published: February 2020

The Li-air battery has received much interest in the last few years as the global energy demand is growing and the availability of fossil energies becomes limited. At present, the specific energy of Li-ions battery is limited to 150 W.h/kg whereas the new approach of Li-air battery offers a theoretical specific energy superior to 1000 W.h/kg [1]. This value is comparable to the specific energy of gasoline for automotive application [2]. For this reason, the main application for Li-air battery is transportation, with the possibility in the next few years to develop an electric car with a same autonomy as gas powered car but cheaper and more environmentally friendly. However, this new technology will remain a research topic for at least the next few years, due to the low cyclability and the wide gap between practical and theoretical energy density.

The project STABLE (“STable high-capacity lithium-Air Batteries with Long cycle life for Electric cars” FP7-NMP 314508) aims to conceive, from innovative materials, a full electrical vehicle with the best performances and the lowest cost possible. The objective is to obtain a battery with a specific capacity higher than 2000 mA.h/g with a cyclability of 100-150 cycles. In this context, a multidisciplinary work team is employing his expertise in material synthesis, characterization and cell assembly to achieve the following tasks: (i) nanostructuration of the Li-anode by electrodeposition, (ii) fabrication of nanostructured carbon cathode and (iii) preparation of ionic liquid (IL)-based electrolyte.

Hydrophobic ionic liquid-based electrolytes have been designed by metathesis of new room temperature ionic liquids (RTILs) and electrochemically tested in split flat cell. The high voltage stability of RTILs (up to 5V) enables a better cyclability of the battery while the capacity stays reasonable (up to 1000 mA.h/g) compared to conventional Li-ions organic electrolytes like the ethylene carbonate (EC)/diethyl carbonate solution (DEC) (Figure 1). Selection of additives and other combinations of ionic liquids have been made in order to reach capacity values up to 4200 mA.h/g in case of Tetraethylene Glycol Dimethyl Ether (TEGDME) which also shows a higher cyclability (up to 10 cycles). Moreover, the RTILs are stable at higher temperatures (> 300˚C), non-flammable and, therefore, more suitable for electrical vehicles.

[1] Christensen J. et al., J. Electrochem. Soc. 159 (2012) R1-R30

[2] Girishkumar G. et al., J. Phys. Chem. Lett. 1 (2010) 2193-2203

Figure 1: Specific capacities of Li-air batteries using different organic and ionic liquid-based electrolyte for the first three discharges.
High Capacity Li/S Battery for Advancing Commercialization
Authors: Choi Gyeong-rin , Cheong Min-Young , Song Jongchan , Kim Hee-Tak , Lee Yongeui , Kim Chulhwan , Hong Young-Jin
Published: February 2020

Rechargeable Li/S batteries are promising candidates for portable electronics, electric vehicles and energy storage system due to their high specific energy and low cost. Many researchers have reported remarkable results in this area, but there are still huge obstacles for commercialization in terms of sulfur loading level for higher specific energy and higher stabilization for lithium metal anode. To solve these problems, we have researched with two aspects. One is attempting to realize highly loaded sulfur cathode with large utilization by impregnating carbonaceous conductive network with nano-sized sulfur. The other is preventing sulfide-shuttle by separator coated with negatively charged material.

Using nano-sized sulfur has advantages not only for increasing networks for sulfur-carbon, but also for obtaining enough space against expansion during lithiation. Furthermore, the conductive network of sulfur-carbon can be more stably maintained with cycling which gives long life span as compared to micro-sized sulfur cathode. Nano-sulfur was fabricated using the conventional milling process in water added with glycerol. Ketjen Black with high surface area and aqueous PVP-PEO mixture were used as a conductive material and binder respectively. Finally, cathode electrodes were prepared with high sulfur contents of 70 wt% and elevated sulfur loading of 3.0 mg/cm2. Electrochemical measurements were carried out using CR2032 coin-type cell system. Initial specific capacity and capacity retention were more than 1,000mAh/g(sulfur) and 80% after 100 cycle respectively. Adapting separator coated with negatively charged moiety significantly decreased the over-charging. This phenomenon can be interpreted as an effect of the negative moiety on separator to repulse the soluble polysulfides which move toward the surface of anode.

Detailed properties up to 300 cycles for pouch cell will be discussed. We believe that the nano-sized sulfur and separator coated with negative moiety can be helpful to advance the commercialization of lithium sulfur battery with high specific energy density more than 300Wh/kg.
Research on Electrocatalytic Centers in Gas Diffusion Electrodes By SECM
Authors: Schwager Patrick , Schwenzel Julian , Wittstock Gunther
Published: February 2020

Due to the higher energy density, compared to state of the art lithium-ion-technology, lithium-air-batteries have raised hope for application, especially in the field of electric mobility. The functionality of lithium-air-batteries is based on the reduction of oxygen within a gas diffusion electrode. The ideal reaction product is lithium peroxide. This process is reversed when charging the battery and can be affected by catalysts. Due to the fact that organic electrolytes are used, different intermediates can be generated during the reduction of oxygen [1,2]. These intermediates are highly reactive and may lead to the degradation of the gas diffusion electrode and/or the organic electrolyte. Furthermore, lithium peroxide formed during discharge is known to clog the pores of gas diffusion electrodes before the discharge process is completed [3]. In order to avoid these effects, further research is essential.

In our approach we developed a setup which allows monitoring the oxygen permeability of the gas diffusion electrode while discharging (oxygen reduction reaction). The process of clogging as well as the mechanisms of charging in gas diffusion electrodes in organic electrolytes are investigated using positionable microelectrodes in a SECM setup (scanning electrochemical microscopy).

References:

[1] McCloskey, B.D. et al., J. Phys. Chem. Lett,.
2011, 2, 1161-1166

[2] Wu, X. et al., Jounal of Power Sources,
2011, 196, 9631-9639

[3] Read, J., J. Electrochem. Soc., 2002, 149, 9, A1190-A1195
Analysis of the Influence of a Short Term Thermal Stress on the Performance and the Characteristics of Lithium Ion Cells
Authors: Bohn Pamina , Komsiyska Lidiya , Wittstock Gunther
Published: February 2020

For several years lithium-ion batteries have been commercially used in small portable devices such as camcorders, laptop computers, cell phones and other electronic devices. Battery lifetime plays only a minor role in such applications due to rapid innovation and strong competition. However, the increasing demand for lithium-ion batteries in the automobile market requires drastic increase in battery lifetime and safety.[1]

All compounds in a lithium-ion battery are sensitive to higher temperatures. For example the electrolyte, which is critical in forming the Solid Electrolyte Interface (SEI), is extremely reactive with humid air and has the lowest boiling point of all battery compounds. Equally sensitive is the separator, which has a melting temperature of 130 to 165°C. [2] The majority of existing life-time and performance prognoses are based on long term temperature influences over numerous charging/discharging cycles (such as in a climate chamber at 40°C). Automotive lithium-ion cells must endure multiple production processes during the fabrication of a high-end battery system, such as contact welding, where the cells are exposed to elevated temperatures for a short period of time.

This research analyzes the behavior and performance of lithium-ion cells after a short thermal stress. A new laboratory cell in two electrode arrangement has been developed in this study in order to perform in-situ short term thermal stress tests on both electrodes. For the current study commercially available lithium cobalt oxide (LiCoO2) cathodes, graphite anodes and an electrolyte consisting of a solution of lithium salt (e.g. LiPF6) in a mixed organic solvent have been used. This novel cell allows for the exact targeting of various components with heat. The thermal stress has been performed after the cell formation with different temperatures ranging from 60 to 250°C. Electrochemical impedance spectroscopy (EIS) has been used to detect changes, caused by the temporary thermal stress. The morphology and the 3D structure of the thermally stressed electrodes has been examined using Scanning Electron Microscope (SEM) and high resolution Computer Tomography (CT). In addition the thermal characteristics such as the thermal conductivity of the electrodes has been studied using Differential Scanning Calorimetry (DSC) and Laser Flash Analysis (LFA) in order to estimate the temperature propagation in automotive lithium-ion cells during pack assembly.

[1] J. Vetter, P. Novák, M.R. Wagner, C. Veit, K.-C. Möller, J.O. Besenhard, M. Winter, M. Wohlfahrt-Mehrens, C. Vogler, A. Hammouche; Ageing mechanisms in lithium-ion batteries. J. Power Sources 147 (2005) 269–281

[2] M. Yoshio, R.J. Brodd, A. Kozawa; Lithium-Ion Batteries, Science and Technologies; Springer (2009)
Kkr-CPA Calculations with Accounting for Chemical Disorder in Relation to Electrochemical Properties of the Cathode Materials for Li-Ion Batteries
Authors: Molenda Janina , Baster Dominika , Tobola Janusz
Published: February 2020

Keywords: first principles calculations, Li-ion batteries, cathode materials, electrochemical properties, transport properties, electronic structure

We focus mostly on first principles calculations of intercalation type cathode materials emphasizing the interplay between a remarkable effect of oxygen vacancy on density of states (especially in the vicinity of band gap) and relative occupancy of alkaline sites. We have used spin-polarized Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA) [1-3], which allows to account for chemical disorder (vacancy defects) both on alkaline [4] and O sites. This approach may describe the particular case of fully disordered model (treating chemical disorder as random), which keeps the same unit cell whatever the lithium (sodium) and oxygen contents. Such a model is complementary to possible ordered supercell approximants of the majority intercalated cathode material systems, which require multiplication of unit cell and modification of their symmetry.

First principles calculations with accounting for chemical disorder, if applied for the description of the process of lithium or sodium intercalation, allows to predict and design performance-related properties of cathode material, on the basis of its structural, thermal and transport properties (XRD, electrical conductivity, thermoelectric power, electronic specific heat).

Acknowledgements

The project was funded by the National Science Centre Poland (NCN) on the basis of the decision number DEC-2011/02/A/ST5/00447.

[1] S. Kaprzyk and A. Bansil, Phys. Rev. B 42, 7358 (1990).

[2] A. Bansil, S. Kaprzyk, P. E. Mijnarends, and J. Tobola, Phys. Rev. B 60, 13396 (1999).

[3] T. Stopa, S. Kaprzyk, and J. Tobola, J. Phys.: Condens. Matter 16, 4921 (2004).

[4] J. Tobola, S. Kaprzyk, and H. Scherrer, J. Electron. Mater. 39, 2064 (2010).
Performance of Polyphosphazene Based Gel Polymer Electrolytes in Combination with Lithium Metal Anodes
Authors: Jankowsky Sebastian , Moretti Arianna , Passerini Stefano , Wiemhöfer Hans-Dieter
Published: February 2020

Polyphosphazene based polymer electrolytes exhibit excellent thermal and electrochemical properties accompanied by a high stability versus lithium metal anodes [1]. The combination of the cross-linked polymer matrix with electrolytes based on organic carbonates or ionic liquids leads to ionic conductivities of 1 mS/cm at 30 °C and good lithium transference numbers. Even with high amounts of liquid additives, the mechanical stability is suitable for use as ion conducting polymeric separator membrane for lithium ion cells. Here, we present the electrochemical performance of different “MEEP” based gel polymer elecrolytes and the galvanostatic cycling behaviour using cells with lithium metal anodes (cf. Fig. 1) and different cathode materials. The results indicate a very good cycling stability due to the high stability of the polymer in contact with metallic lithium. Compared to other gel polymer electrolytes in combination with carbon anodes [2] the “MEEP” based gel polymers exhibit good cycling stability with higher specific capacities.

Fig. 1. Galvanostatic cycling of a full cell with polymeric gel electrolyte from MEEP using LiFePO4cathode and metallic lithium as anode.

The authors acknowledge funding by the German Ministery for education and research (BMBF) within the project “MEET Hi-EnD“.

[1] Jankowsky S. et al., J. Power Sources
2014, 253, 256-262.

[2] Isken P. et al., J. Power Sources
2013, 225, 157-162.
Ion Transport Numbers of Gel Polymer Electrolytes Based on Block Copolymers Containing Ethylene Oxide Sidechains
Authors: Schaefer Moritz , Lex-Balducci Alexandra
Published: February 2020

Nowadays, lithium ion batteries (LIBs) play a key role in the field of portable electronic devices. In the last decades, LIBs have also been considered for large scale applications like in electric vehicles (EVs) or hybrid electric vehicles (HEVs). In state of the art LIBs, mainly liquid electrolytes, consisting of two or more carbonate solvents (e. g. ethylene carbonate and dimethyl carbonate) and a lithium salt, are used. But despite their advantage of displaying a high conductivity at room temperature, the disadvantages like a low flash and boiling point and the danger of leakage in case of cell damage, show that an improvement in safety is necessary.

As alternative solid polymer electrolytes were developed, but their low room temperature conductivity is still an obstacle to their use in commercial LIBs. Another approach is the use of gel polymer electrolytes (GPEs), which combine the advantages of liquid and solid polymer electrolytes. They display a high conductivity at room temperature while having a sufficient mechanical stability to be used as separator. Another advantage is that GPEs are able to prevent leakage, as the liquid electrolyte is immobilized in the polymer matrix.1

In this work we report on the development of novel gel polymer electrolyte systems based on non-commercial available amphiphilic block copolymers matrices comprising a norbonene backbone. The synthesis of monomers with different side chains, and the use of ring opening metathesis polymerization2, a living polymerization method allow the tailoring of the properties of the polymer. The polymer matrix, comprising ethylene oxide side chains with different lengths, is thermally stable up to 180 °C and shows microphase separation, proven by DSC measurements. The resulting GPEs were investigated regarding their conductivity and electrochemical stability. Particular attention was put on the investigation of the transport properties of the GPEs, using PFG-NMR and Raman-spectroscopy. The influence of the length of the ethylene oxide side chains on the diffusion coefficients of the ions and the Li+ complexation was studied.

[1] P. Isken, M. Winter, S. Passerini, A. Lex-Balducci J. Power Sources
2013, 225, 157-162.

² C. W. Bielawski, R.H. Grubbs, Prog. Polym. Sci.
2007, 32, 1 - 29.
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.
First Principles Search for Dual-Functioning Electrode/Electrocatalyst Materials for Li-O2 Cells
Authors: Kirklin Scott J. , Trahey Lynn , Chan Maria K. Y. , Thackeray Michael M. , Wolverton Chris
Published: February 2020

By combining functionalities of Li-ion and Li-O2 chemistries in a single cell, it may be possible to significantly improve battery capacity. Recent work by Trahey et. al.
[1] has demonstrated a new class of dual-functioning electrocatalyst/electrode for Li-O2 cells based on Li5FeO4. We have used DFT to systematically explore other reactions of this kind with the aim of guiding future experimental studies. We utilized the Open Quantum Mechanical Database (OQMD) to screen for other reactions similar to that of Li5FeO4. From an initial set of hundreds of reactions, we created a series of constraints and reduced this list to a handful of compositions which are most likely to produce batteries with desirable performance. The results of this study will be discussed in this presentation.

Reference

1. L. Trahey, C. S. Johnson, J. T. Vaughey, S.-H. Kang, L. J. Hardwick, S. A. Freunberger, P. G. Bruce, and M. M. Thackeray, Electrochem.Solid-State Lett., 14(5), A64-A66 (2011).
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.
Rechargeable Aqueous Lithium-Ion Battery Zn/LiFePO4 for Large Scale Energy Storage
Authors: Yesibolati Nulati , Umirov Nurzhan , Koishybay Aibolat , Omarova Marzhana , Doskumbay Abilkhaiyr , Kurmanbayeva Indira , Zhang Yongguang , Zhao Yan , Bakenov Zhumabay
Published: February 2020

1.
Introduction

Rechargeable aqueous lithium batteries (RALBs) are promising alternative to bypass safety issues of lithium-ion batteries (LIBs) with organic electrolyte. Furthermore, fast lithium diffusion in aqueous electrolyte media could allow for the operations under high electric current conditions required for high power supply [1]. J. Dahn et al
[2] reported on a VO2/LiMn2O4rechargeable aqueous battery, based on the “rocking chair” concept adopted from LIBs. However, this type of batteries had serious issues with cyclability.

Here, we report for the first time on a system comprising an intercalation LiFePO4(LFP) cathode and a Zn metal anode in an aqueous electrolyte, and on large-scale RALB based on this concept with enhanced cycle performance and energy density.

2. Experimental

All electrochemical tests were carried out using galvanostat/potentiostat VMP3 (Biologic) and two-electrode Swagelok-type cells and a rolled cylindrical battery configuration (ca. 600 mAh per cell). The commercial LiFePO4 (Hohsen Co, Japan) powder and zinc foil (Good Fellow, England) were used as cathode and anode, respectively. Graphite (Sigma Aldrich) and stainless steel (SUS316) rods were used as current collectors for the positive and negative sides, respectively. Absorptive glass mat (AGM) acted as a separator. The electrolyte was a mixed aqueous solution of zinc and lithium salts. Galvanostatic charge/discharge cycling was performed at various current densities from 0.6 C to 60 C (1 C corresponds to a current density of 170 mA g-1) at room temperature and the voltage cutoffs 1.0-1.4 V vs. Zn2+/Zn.

3. Results and discussion

The electrochemical performance of Zn|LFP is presented in Fig. 1. The battery exhibited discharge capacities of 75 mAhg-1 and 43 mAhg-1 at high current densities of 30 C and 60 C, respectively, and maintained excellent stability and coulombic efficiency with a capacity of 102 mAhg-1 after 300 cycles when cycled at 6 C (Fig. 1b).

The large scale battery (stack of cylindrical cells) showed 590 mAh/cell capacity at the initial cycle and could maintain 550 mAh/cell capacity after 10 cycles as shown in Fig. 1c. The further details of these studies will be presented at the Meeting.

Acknowledgments

This research was supported by the “Nazarbayev University Corporate Fund of Social Development” grant.

References

1. Wei Tang, Yuping Wu, Kian Ping Loh, Energy Environ. Sci., 6 (2013) 2093–2104

2. W. Li, J.R. Dahn, D.S. Wainwright, Science 264 (1994) 1115-1118.