bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Sulfur Loading of Cathodes for Li-S Batteries
Authors: Liu Wen , Li Yong , Guo Gui , Pei Hai Juan , Fu Wen Zheng , Xie Jingying 
Published: February 2020

Lithium sulfur batteries have attracted the most attention owing to their high energy density (2600Wh/kg), while the specific capacity and capacity retention of sulfur electrodes play a crucial role on increasing the energy density of lithium sulfur batteries. Many researches focus on the materials with very high specific capacity per gram of sulfur but very low sulfur content and cells with very low sulfur loading of cathodes [1-3]. In this work, the cells with much higher sulfur loading of electrodes (4.34mg S/cm2, named as S-L and 7.24mg S/cm2, named as S-H) show better electrochemical performance.
Fig. 1(a) shows the first discharge/charge potential curves of lithium sulfur batteries with S-L and S-H as cathodes. Two plateaus (about 2.35V and 2.10V) in the discharge curve and one plateaus (about 2.20-2.40V) in the charge curve are observed, which agree well with the previous work [4]. Comparison of cycling performance between S-L and S-H cathode was shown in Fig. 1(b). S-L cathode shows an initial specific capacity of 845mAh/g at 50mA/g between 1.50-2.80V, which exhibits a discharge capacity of 763mAh/g after 45 cycles with a capacity retention of 90.3%. Moreover, the cell with S-H cathode delivers 836mAh/g and 754mAh/g at the first cycle and the 25th cycle, respectively. The excellent electrochemical performance of high sulfur loading of electrodes makes the development of high energy Li-S batteries possible.
Fig. 1 (a) The first discharge/charge potential curves of lithium sulfur batteries with S-L and S-H as cathode between 1.50-2.80V; (b) Comparison of cycling performance between S-L and S-H cathode.
Reference:
[1] F. F. Zhang, X. B. Zhang, Y. H. Dong, L. M. Wang, J. Mater. Chem., 2012, 22, 11452.
[2] S. Evers, L. F. Nazar, Chem. Commun., 2012, 48, 1233.
[3] G. Zheng, Y. Yang, J.J. Cha, S. S. Hong, Yi Cui, Nano Lett., 2011, 11, 4462.
[4] L. Xiao, Y. Cao, J. Xiao, B. Schwenzer, M. H. Engelhard, L. V. Saraf, Z. Nie, G. J. Exarhos, J. Liu, Adv. Mater., 2012, 24, 1176.
Study of Cathode Materials for Li Ion Batteries with EPR and High Field EPR Spectroscopy
Authors: Jakes Peter 
Published: February 2020

In this work we present EPR measurments done with electrode materials
from Li ion batteries. A comparison of different systems shows, why EPR is
useful studying cathode and anode materials as well as degradation. For the
interpretation of the EPR spectra, high filed measurements, measurments at
different temperatures and in situ measurements are very useful.
Self-Limiting Lithiation and Viscoplasticity of Electrode Nanoparticles in Li-Ion Batteries
Authors: Drozdov Aleksey D , Sommer-Larsen Peter , Christiansen Jesper deClaville 
Published: February 2020

A model is derived for the viscoplastic behavior of a host medium driven by stress-induced diffusion of guest atoms. The constitutive equations are applied to study development of stresses in a spherical electrode particle subjected to insertion of lithium. Numerical simulation demonstrates ability of the model to capture basic phenomena observed in anode nanoparticles under lithiation: formation of a sharp interphase between a Li-poor core and a Li-rich shell, slowing down of the interphase motion revealed as self-limiting lithiation, and growth of tensile hoop stresses at the outer surface of a particle leading to its fracture. Good agreement is demonstrated between observations on interphase propagation in silicon nanoparticles and predictions of the model.
Our approach is grounded on the following assumptions:
Electrochemical alloying of guest atoms with a host medium is treated as their (temporary or permanent) immobilization in an electrode particle.
Two types of guest atoms are distinguished: mobile and immobilized (trapped). Transport of mobile atoms is described by the diffusion equation with a reaction term (that accounts for their binding with host atoms) and diffusivity affected by concentration of immobilized atoms. The rate of immobilization is proportional to concentrations of mobile atoms and available traps.
A sharp boundary (interphase) between the domains rich and poor in guest atoms is formed when the rate of trapping exceeds the rate of diffusion.
To characterize development of stresses in a host medium, plastic flow is associated with evolution of its structure (each elementary act of plastic deformation reflects rearrangement of the host matrix induced by alloying with a guest atom).
Within the regular solution model, free energy of a mobile atom is treated as the sum of two (entropic and enthalpic) components. Self-limiting lithiation of electrode particles is described by presuming the Flory-Huggins parameter to be affected by pressure.
To reduce the number of adjustable parameters in the governing equations, simplifying assumption are introduced: (i) changes in elastic moduli with concentration of guest atoms are disregarded, (ii) transport of guest atoms through a host medium is considered within the concept of small strains, (iii) anisotropic volume expansion of electrode particles is not taken into account.
Ability of the model to describe self-limiting lithiation of silicon nanoparticles is illustrated in Figure 1 where dimensionless thickness of a Li-rich outer shell h is plotted versus dimensionless time t(symbols: experimental data (McDowell et al., 2012), filled circles: results of numerical simulation).
Acknowledgement: Financial support by the EU Commission through FP-7 Project Evolution-314744 is gratefully acknowledged.
References:
1. A.D. Drozdov, Int. J. Solids Struct. 2014 (in press).
2. A.D. Drozdov, P. Sommer-Larsen, J.deC. Christiansen, J. Appl. Phys. 2014 (in press).
Thermo-Electrochemical Simulation of Li-Ion Cells Under Abuse Condition
Authors: Tanaka Nanako , Bartsch Philipp , Danzer Michael A. , Döring Harry , Bessler Wolfgang G. 
Published: February 2020

Safety of lithium-ion cells is one of the most important aspects of battery research [1]. As a pilot study preliminary to building an early-alert heat management system for lithium-ion cells, we present 1D multi-scale simulation of a single cell with exothermic reactions which induce thermal runaway. The thermo-electrochemical model used in this work includes electrochemical and thermochemical kinetics in range from micro to macro scales [2]. Lithium insertion and extraction in active materials are assumed to follow Butler-Volmer kinetics. The model cell in this study has mesocarbon microbeads (MCMB) in anode and a blended electrode of LiMn2O4 (LMO) and LiNi0.8Co0.15Al0.05O2 (NCA) in cathode. The thermodynamic properties of the pure electrode materials are obtained through published half-cell potentials [3,4,5]. The property of blend material is formulated based on an assumption observed through experiments by Tran et al [6].
To simulate runaway events, we take into account thermal degradation mechanisms both at anode and cathode sides at elevated temperature. At the anode, four exothermic reactions are considered; solid electrolyte interface (SEI) decomposition, SEI formation, ethylene oxidation and reaction of lithium with water. Similarly, oxygen release from NCA and oxidation of solvent (ethylene carbonate) are modeled at the cathode. The reactions are assumed to follow Arrhenius behavior and Tafel type expression for non-charge transfer reaction and charge transfer reaction, respectively. The pre-exponential factor and activation energies of the reactions are taken from either literature or fits with published differential scanning calorimetry (DSC) experiments.
Thermal simulations are used to predict the onset of runaway events under cycling from room temperature up to 333 K of ambient temperature. The cycles are tested under current rates of 1, 2, 3 and 4C. Figure 1 shows the heat resulting from cycling with 4C leading to a chain of exothermic reactions approximately at 350 K inducing thermal runaway.
Furthermore, predictions of temperature and kinetic behavior in case of short circuits are presented (Figure 2). The comparison with experimental measurement is discussed.

Acknowledgement

Financial support by the Volkswagen foundation is gratefully acknowledged.

References

[1] D. Doughty, E.P. Roth, ECS Interface, 2012.
[2] N. Tanaka, W. Bessler, Solid State Ionics, http://dx.doi.org/10.1016/j.ssi.2013.10.009 (2013).
[3] Y.F. Reynier, R.Yazami, B. Fultz, J. Electrochem. Soc., 151 (3) (2004) A422-A426.
[4] K.E. Thomas, C. Bogatu, J. Newman, J. Electrochem. Soc., 148 (6) (2001) A570-A575.
[5] H. Yang, J. Prakash, J. Electrochem. Soc., 151 (8) (2004) A1222-A1229.
[6] H.Y. Tran, C. Taubert, M. Fleischhammer, P. Axmann, L. Knuppers, M. Wohlfahrt-Mehrens, J. Electrochem. Soc., 158 (5) (2011) A556-A561.
Thin and Flexible Solid State Electrolytes for Ambient and Middle Temperature Storage Systems
Authors: Ahlbrecht Katharina , Hupbauer Cornelius , Tübke Jens , Hoffmann Michael J 
Published: February 2020

Solid state electrolytes are generally used in high-temperature systems such as fuel cells or sodium/sulfur batteries. They are mostly found in stationary energy storage applications. On the one hand solid state electrolytes have a high ionic conductivity especially at elevated temperatures. On the other hand, they are very brittle and fragile because they are made of ceramic or glass-like materials. To use the solid state electrolyte in next generation systems, such as in Li/S, Li/Air or sodium-based systems at ambient or middle temperature, the solid state electrolyte is embedded in a flexible, ductile and non-metallic material by using a recently developed manufacturing process. The advantage of those materials is the possibility of their plastic deformation under stress.
By using adjusted and optimized electrolytes for each electrode in the Li/S battery, intrinsic parasitic effects like the polysulfide shuttle mechanism or electrolyte degradation at the side of the alkaline metal anode could be prevented. As an alternative to lithium today sodium-based systems have become an interesting subject for researchers. Due to the low melting temperature of sodium (about 100 °C), it is conceivable to use molten sodium as an anode separated with a thin, flexible and stable solid state electrolyte from a cathode. With this design a formation of dendrites and a reaction with a liquid electrolyte should be avoided and improved cycling stability can be obtained.
Physical Vapor Deposition of Li7La3Zr2O12 for All-Solid-State Thin Film Li Batteries
Authors: Lobe Sandra , Stemme Florian , Tsai Chih Long , Finsterbusch Martin , Dellen Christian , Uhlenbruck Sven , Buchkremer Hans Peter 
Published: February 2020

The liquid solvents used as electrolytes in conventional Li ion batteries limit the operating temperature range and cause safety problems due to insufficient electrochemical stability. With purpose to avoid these disadvantages solid electrolytes, like lithium conducting oxides, sulfides or phosphates can be used. A promising oxide is the garnet-like Li7La3Zr2O12 that shows one of the highest total Li ion conductivities (about 10-4 S cm-1 at room temperature) in this class of materials. It also enables a wide application range due to its thermal stability and chemical resistance against possible electrode materials, e.g. metallic Lithium.
In order to compensate the lower Li ion conductivity compared to liquid electrolytes current work is focused on thin electrolyte layers. Hence, main research aspect of the presented work is the thin film processing of Li7La3Zr2O12 with physical vapor deposition methods, especially RF magnetron sputtering. The growth conditions are optimized with regard to synthesize stoichiometric, crack-free and smooth thin films. Deposition is followed by thermal treatment of the as-grown samples to improve the crystallinity which should in turn improve the Li ion conductivity. The composition, structure and the electrochemical behavior of the resulting thin films are analyzed in order to deposit all-solid-state thin film batteries.
Combined IR and Raman I
n Situ Microscopy on Single Particles - A New Tool for Interface Studies
Authors: Novak Petr , Lanz Patrick 
Published: February 2020

Vibrational spectroscopy is well suited to the investigation of processes occurring in lithium-ion batteries during electrochemical cycling. The combined application of Raman and IR spectroscopy offers additional advantages connected to the complementary nature of the two methods. Whereas Raman spectroscopy is particularly sensitive to local structural changes of the electrode material, IR spectroscopy provides a good way of probing the interface with the organic electrolyte. Employing microscopic methods and a specially adapted cell allowed spatial resolution and the recording of in situ data, respectively.
In this contribution, we will describe the first application of these spectroscopic methods to the characterization of the same spot at a single working particle. Originally, combined Raman and IR microscopy was first developed by using glassy carbon, which offers the advantage of exhibiting excellent IR reflectivity. However, because glassy carbon is unable to intercalate lithium, the method was further developed and applied to a single, graphite particle. Unlike conventional compound electrodes consisting of microscopic graphite powders, this allows the measurement of IR spectra with good signal-to-noise ratios. This study is thus employed to showcase a powerful application of the combined same-spot spectroscopic method. The automated measurement of Raman and IR spectra provides an efficient way of correlating information on the electronic state of the electrode (intercalation) with effects related to the interface with the electrolyte (SEI). Corresponding results are presented and discussed in this contribution.
All Solid-State Lithium Batteries Assembled with Hybrid Solid Electrolytes
Authors: Jung Yun-Chae , Choi Jeong-Hee , Lee Sang-Min , Kim Dong-Won 
Published: February 2020

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices, electric vehicles and energy storage systems, due to their high energy density and long cycle life [1,2]. However, safety issues still prevent full utilization of these batteries. One of the most efficient methods to enhance the battery safety is to use solid electrolyte [3-5]. Solid inorganic electrolytes present potential advantages, such as a wide electrochemical stability window, enhanced thermal stability, absence of solvent leakage and high resistance to shocks, which are important safety assets. However, sheet manufacturing, especially using thin-film technologies for making large-scale batteries, is considered to be difficult because of brittle characteristics of ceramic materials. In this work, the hybrid solid electrolytes composed of lithium aluminum germanium phosphate (LAGP) and poly(ethylene oxide)(PEO) were prepared in the form of flexible thin film, and their electrochemical properties were investigated. Their morphological properties studied using SEM, EDS and XRD. The ionic conductivities and electrochemical stability of hybrid solid electrolytes were much higher than those of PEO-based polymer electrolyte. All solid-state lithium batteries assembled with hybrid solid electrolyte exhibited high discharge capacity and excellent capacity retention with a coulombic efficiency exceeding 99.5% at 55 oC.

References

[1] J. M. Tarascon, M. Armand, Nature 414 (2001) 359.
[2] P. G. Bruce, B. Scrosati, J. M. Tarascon, Angew. Chem. Int. Ed. 47 (2008) 2930.
[3] N. Kamaya, K. Homma, Y. Yamakawa, M. Hirayama, R. Kanno, M. Yonemura, T. Kimiyama, Y. Kato, S. Hama, K, Kawamoto and A. Mitsui, Nat. Mater. 10 (2013) 682.
[4] H. S. Jadhav, M.S Cho, R. S. Kalubrame, J. S. Lee, K. N. Jung, K. H. Shin, C. J. Park, J. Power Sources 241 (2013) 502.
[5] Y. Li, C. A. Wang, H. Xie, J. Cheng, J. B. Goodenough, Electrochem. Commun. 13 (2011) 1289.
Effect of Temperature and Tfsi Concentration on Lithium-Ion Diffusion in (PVDF-HFP)-PYR14 TFSI-LiTFSI Gel Electrolytes
Authors: Sobrados Isabel , Sanz Jesus , Amarilla Jose Manuel , del Rio C. , Morales Enrique 
Published: February 2020

Lithium batteries have been considered as the most probably next generation of power sources for portable electronic devices and electric vehicles. However, safety risks related to the use of highly flammable liquid electrolytes in combination with high voltage electrodes are the main obstacle to their introduction into the market. Recently ionic liquids have emerged as potential materials to substitute the conventional organic carbonate-based liquid electrolytes. In this work we report on the effect of temperature and lithium salt molar concentration on lithium ion diffusion in (PVDF-HFP)-PYR14TFSI-LiTFSI gel electrolytes. TFSI molar ratios range from 0,05 to 1 mol%. The self-diffusion coefficient of lithium ions (D 7Li) was measured at temperatures from 20 to 100°C using the pulsed-field gradient NMR (PFG-NMR) method by using a Bruker 400MHz Avance NMR spectrometer with a magnetic field of 9.4 T. A stimulated echo pulse sequence with gradient pulses of duration (δ) of 1-2 ms and an observation time (Δ) equal to 20 ms was applied. The decay of the signal in dependence on the gradient strength g results in the diffusion coefficient by fitting the exponential decay function. A parallel analysis was made for PYR14TFSI/TFSI ionic liquid electrolytes.
The results obtained indicate that the value of D 7Li at high temperature for both liquid and gel electrolytes is practically independent on the LiTFSI molar concentration, while larger differences have been detected at low temperatures, in accordance with ionic conductivity data. The temperature dependence of the calculated self-diffusion coefficients fit the Arrhenius equation. The values of the activation energy Eac, calculated by plotting the shelf diffusion coefficient vs. 1/T, depends on the relative concentration of the lithium salt in the gel, increasing when TFSI molar ratio goes from 0,05 to 1 mol% for both liquid and gel electrolytes.
Thermodynamic Explanation of Orientation-Dependend Expansion of Lithiated Si Nanowires
Authors: Rohrer Jochen , Moradabadi Ashkan , Kaghazchi Payam , Albe Karsten 
Published: February 2020

Due to its high mass-specific capacity Si is an attractive anode material for Li ion batteries.
The highest capacites have been achieved for Si nanowires, wires consisting of a crystalline core and an amorphous shell.
During first-cycle lithiation, both the amorphous shell and the crystalline core transform into amorphous LixSi where x may reach a maximum value of ~4.4 at full lithiation.
During first lithiation, it has been observed that Si nanowires expand differently into different directions [1].
In particular, expansion into <110> is largest while expansion into <111> is smallest.
It has been suggested that this behaviour is due to an orientation-dependent diffusion rate of the interface
between lithiated Si (amorphous LixSi) and the crystalline core [1,2].
In this work we use ab initio density functional theory calculations to study interfaces between lithiated Si and crystalline Si.
In particular we focus on interfaces between Si(100), Si(110) and Si(111) with amorphous Li2Si (a-Li2Si).
a-Li2Si is chosen as model for lithiated Si since it has recently been suggested to coexist with crystalline Si [3].
We find that a-Li2Si/Si{111} interfaces are energetically most favourable,
while a-Li2Si/Si{110} interfaces are the least favourable (among the three considered ones).
Since expansion along <111> generates a-Li2Si/Si{110} interfaces (<1-10> is orthogonal to <111>)
and expansion along <110> generates a-Li2Si/Si{111} interfaces,
our calculations naturally explain experimental observations on a thermodynamic basis.
For completeness, we also study the kinetics of Li across the interfaces.
Preliminary results indicate that Li diffusion barriers are independent of the orientation of the interface.
This implies in particular that kinetics does not hinder a thermodynamic evolution of the system.
References:
[1] H. Yang et al., Nano Lett.
12, 1953 (2012).
[2] M.K.Y. Chan, C. Wolverton and J.P. Greeley, J. Am. Chem. Soc.
134, 14362 (2012)
[3] J. Rohrer and K. Albe, J. Phys. Chem. C
117, 18796 (2013).
Effect of Silica and Tin Oxide Nanoparticles on Properties of Nanofibrous Electrospun Separators
Authors: Zaccaria Marco , Cannucciari Giorgia , Fabiani Davide , Gualandi Chiara , Focarete Maria Letizia 
Published: February 2020

Recently the use of electrospun separators in lithium ion batteries has been studied due to the outstanding properties of the nanofibrous non-woven constructs [1]: high porosity, high pore interconnectivity and wide surface area that lead to a large electrolyte uptake with respect to a commercial microporous separator, e.g. Celgard. This behaviour makes electrospun mats suitable for high ionic conductivity applications in lithium cells. Further improvements in membrane properties can be achieved through dispersion of additives (such as oxides particles) inside nanofibers, aiming at increasing the mechanical, thermal and electrical properties of the polymeric separators, in order to satisfy lithium battery safety concerns and capacity requirements. The use of nanoadditive to improve the properties of electrospun membranes for polymer electrolyte batteries is a quite novel topic, not completely investigated in literature.
In this work Poly(vinylidene fluoride) (PVDF) solutions have been filled with fumed silica and tin oxide nanoparticles and electrospun to produce lithium battery separators. Membrane morphology characterization and energy dissipation spectroscopy have been carried out by means of a scanning electron microscope, in order to evaluate fiber quality, fiber diameter distribution and the presence of the additives inside the material. Thermogravimetric analysis, Differential Scanning Calorimetry, and tensile tests have been used to evaluate thermal stability, thermal and mechanical properties of the separators and to quantify the inorganic fraction. Electrical characteristics have been investigated through dielectric spectroscopy and conductivity measurements in order to ensure the very low electric conductivity of the membranes regarding electronic carriers. Nanoparticle dispersion inside the fibers has been evaluated by means of a transmission electron microscope. Finally, the electrospun separators have been soaked in electrolyte solution to estimate their uptake performance.
[1] F. Croce, M.L. Focarete, J. Hassoun, I. Meschini, B. Scrosati, A safe, high-rate and high-energy polymer lithium-ion battery based on gelled membrane prepared by electrospinning, Energy and Environmental Science, 2011, 4, 921–927.