bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Electrolyte Li+ Ion Concentration on the Growth of Li2O2 Discharge Products
Authors: Wang Deyu , Liu Yang 
Published: February 2020

Organic Li-air battery is represented as the most promising energy-storage technology due to its ultra-high theoretical energy density.1,2 However, how to realize the advantage of high energy density has become one of the most important and urgent challenges. In our opinion, discharge process could be considered as fulfilling Li2O2 crystals in the pores of air cathode. Since supersaturation is the key driving force to influence the insoluble sedimentation process3, the growth of discharge products could be tailored by the activity of Li+ ions and/or reductive species. Therefore discharge products are possible to grow tri-dimensionally, instead of a thin layer, by adjusting Li+ ion concentration in the electrolytes.
In this work, it is investigated the influence of electrolyte Li+ ion concentrations on discharge behavior. As shown in Fig.1, the discharge behaviour could be divided into 3 regions as electrolyte concentration increases from 10-3 M to 5 M. The first region is ranged from 10-3 to 1 M, where discharge capacities are monotonic augmenting. It only delivers 2211 mAh gcarbon-1 at 10-3 M, and quickly ramps to 3013, 6055, and 7529 mAh gcarbon-1 at 10-2, 10-1 and 1 M separately. At 2 and 3 M, the discharge capacity hovers at an extremely high level, 12250 and 13245 mAh gcarbon-1 respectively. As the concentration further increases to 4 M and 5 M, the discharge capacity slumps severely to less than 4000 mAh gcarbon-1. The capacity variation is up to ~600% as a result of the tailoring effect of Li+ ion concentration in the electrolytes. The probable mechanism and further discussion will be presented in the conference.
Reference
1. P.G. Bruce.; S.A., Freunberger, L.J. Hardwick, J. M. Tarascon, Nature Mater. 2012, 11, 19;
2. G. Girishkumar, B. McCloskey, A.C. Luntz, S. Swanson, W. Wilcke, J. Phys. Chem. Lett. 2010, 1, 2193.
3. H.J. Scheel, T. Fukuda, Crystal Growth Technology John Wiley & Sons, Ltd. 2003.
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.