bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Energy and High-Power Electrodes Screened by Microstructure Reconstruction and Model Simulation
Authors: Ender Moses , Illig Jörg , Weber André , Ivers-Tiffée Ellen 
Published: February 2020

Even though it is well-known that high-power and high-energy lithium ion cells require different electrode design rules, conventional analysis methods fail to quantify the key properties of their microstructures. To shed light on the differences between commercial high-power and high-energy cells, their electrode microstructures are analyzed in detail using focused ion beam and micro X-ray tomography. The cells under investigation are a 18650 LiFePO4/graphite power cell and a 18500 LiCoO2/graphite energy cell.
A three-dimensional reconstruction of anodes and cathodes allows for specifying their tailor-made microstructural characteristics. Beside the basic structural parameters (a) volume fractions, (b) surface areas, (c) average particle sizes and (d) tortuosity, a more advanced analysis yields additional information such as: (e) particle size distributions, (f) space-resolved tortuosity values (g) a detailed analysis of different secondary-particle classes.
Based on this array of microstructural information, the specific characteristics of all electrodes are identified with respect to cell performance. This newly gained insight is backed up by model simulations. These are based on a refined homogenized porous electrode model, which is parameterized with the structural parameters extracted from the reconstructions.
This combined approach gives a high-definition picture of tailor-made electrodes and facilitates understanding of rate-limiting mechanisms in high-power and high-energy electrodes. During charging and discharging, the electrochemically active zone spreads out over the entire electrode thickness within the high-power cell. Contrary, it is spatially restricted in both electrodes of the high-energy cell and migrates from the separator towards the current collector. Model simulations show, that this behavior is caused by (i) the lower electrode porosity and (ii) the larger electrode thickness of the high-energy cell. Furthermore, model simulations show, that the maximum discharge current of both cathodes (16C and 4C) is restricted by a depletion limitation of the electrolyte.

Figure 1: Three-dimensional reconstructed microstructures of the high-power cell (a, c) and the high-energy cell (b, d). For the anodes (a, b), the graphite phase is shown in blue with the porosity appearing transparent. For the LiFePO4 cathode (c), the two different agglomerate classes are shown in different shades of green, the carbon additive is shown in gray. For the LiCoO2 cathode (d), the active material is also shown in green and the carbon in gray. The porosity in both cathodes appears transparent.
Electrode Side Reactions, Capacity Loss and Mechanical Degradation in Lithium Ion Batteries
Authors: Xu Jiagang , Deshpande Rutooj , Pan Jie , Cheng Yang-Tse , Battaglia Vince 
Published: February 2020

To further develop lithium ion batteries, it is important to improve the understanding of battery degradation mechanisms. In this presentation, we report the results of a series of experiments which helped establish a relationship between coulombic efficiency, side reactions, capacity loss, and mechanical degradation in lithium ion batteries. Graphite/Li(Ni1/3Mn1/3Co1/3)O2 (NMC) CR2325 full cells of two very different initial anode/cathode capacity ratios (R), both greater than 1, are assembled to investigate their electrochemical behavior. It is observed that, during electrochemical cycling, the cell with a higher R value displays a lower coulombic efficiency than that of a cell with a smaller R value. The cell with the high R value is shown to have less initial capacity yet less capacity fade during cycling. This confirms the hypothesis that coulombic efficiency is not a perfect indicator of capacity fade. These experiments also show that electrolyte reactions on the anode affect the electrolyte reactions on the cathode and there is, thus, “cross talk” between the two electrodes. This work also supports the idea that capacity fade in graphite based cells is a result of the fracturing and repairing of the solid-electrolyte interphase (SEI) on the anode that leads to a lithium imbalance in full cells and that fracture is worse for cells where the anode particles are cycled to a greater percentage of the full capacity.
(Invited) Improved Performance of Lithium-Sulfur Battery with Fluorinated Electrolyte
Authors: Zhang Zhengcheng , Azimi Nasim , Xue Zheng , Takoudis Christos G 
Published: February 2020

Despite the great promise, the Li-S battery poses several technological challenges, including fast capacity fading with cycling, high self-discharge rate, and low energy efficiency. Many of these issues are related to the internal “redox shuttle mechanism,” which results in parasitic reactions of dissolved lithium polysulfides (Li2Sx, x=4-8) with the lithium anode and the loss of sulfur active material.[1] A problem arises because of the dissolution of lithium polysulfide from the cathode into the electrolyte solvent¯typically a mixture of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME).
In this paper, we present a new electrolyte containing an organo-fluorine compound, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) for the first time for the lithium-sulfur battery. Fluoroether compound exhibits much higher hydrophobicity than its non-fluorinated counterpart, and as a result, its interaction with hydrophilic Li2Sx is quite weak. A solubility test clearly indicated that Li2S8 has very limited solubility in the mixture of Fluoroether 3 and DOL at a 1:1 or greater volume ratio, whereas it completely dissolves in the mixture of DOL/DME (1:1 ratio), a state-of-the-art (SOA) electrolyte for the Li-S battery (Fig. 1). The low solubility of lithium polysulfides in fluoroether solvent significantly affects their diffusion into the bulk electrolyte, mitigating the shuttle effect and enhancing the charging efficiency (Fig. 2).[2] The new fluorinated electrolyte suppressed the deleterious shuttling effect and improved the capacity retention and coulombic efficiency in cell tests. In addition, it was found to eliminate the self-discharge of the lithium-sulfur battery.

Figure 1
Sulfur Cathode for High Performance Lithium Sulfur Batteries
Authors: Ryu Hee-Yeon , Woo Hee Jin , Lee Yoon Ji , Park Sang Jin , Kim Dong Hee , Lee Ho-Teak 
Published: February 2020

Over the last few decades, electric vehicles (HEV, PHEV, BEV) have been developed as one of the solution to the CO2emission problems. For the successful electric vehicles commercialization, batteries with high energy density are required. Among several kinds of batteries, the lithium sulfur battery is a very attractive candidate, because elemental sulfur has the highest theoretical capacity(1,672 mAh/g) and highest theoretical energy density(2,600 Wh/kg) of all known cathode materials. However, lithium sulfur battery has some problems about cycle life and sulfur utilization efficiency. Recently, a lot of researchers are focused on solving those problems.
In this research, electrochemical properties of lithium sulfur battery were investigated by applying mesoporous carbon and carbon fiber sheet to sulfur cathode. Mesoporous carbon with controllable pore sizes (4nm, 12nm, 25nm) was fabricated and the pores are filled with sulfur for mesoporous carbon/sulfur composites. The optimal pore size of mesoporous carbon was chosen by cell performance test. Carbon fiber sheet was also applied to cathode as a frame structure to have chemical reaction even higher thickness of electrode with maximum sulfur loading. Using those mesoporous carbon/sulfur composites and carbon fiber sheet, lithium sulfur pouch cell was designed, fabricated and tested.
As a result, the discharge capacity of lithium sulfur pouch cell shows 1,206 mAh/g_S with sulfur loading amount of 8.5mg/cm².

Figure 1
Sodium-Ion Battery Cathode Material Synthesized By Spray Pyrolysis
Authors: Shen Kuan-Yu , Lengyel Miklos , Wang Louis S. , Axelbaum Richard L. 
Published: February 2020

Lithium-ion batteries have been the dominant choice for batteries for decades, however there are concerns related to the limited availability of lithium, which could potentially increase the cost and affect further implementation. As a promising alternative, sodium-ion batteries have attracted significant attention in recent years [1, 2]. The potential markets for sodium-ion batteries could range from devices where cycle life and cost are more prevailing factors than energy density, such as grid-scale energy storage for smart grid applications. A single-step, facile spray pyrolysis is being evaluated in this group for the synthesis of sodium-ion battery cathode materials.
In the current study, Na0.44MnO2 was selected due to its promising electrochemical performance, unique structure, and its similarity to transition metal oxides [3, 4]. Figure 1 shows the SEM image of Na0.44MnO2 annealed at 800 ºC. The material demonstrates a uniform, rod-like morphology. Figure 2 displays the XRD data of samples annealed at different temperatures for two hours. Na0.44MnO2 has an orthorhombic lattice cell (pbam space group) and is isostructural with Na4Mn4Ti5O18. The sample annealed at 700 ºC displays impurity peaks around the 30º 2θ. These impure phases may be related to the incomplete decomposition at this temperature. There are no additional phases observed in the 800 ºC and 900 ºC annealed samples. Figure 3 shows the first cycle voltage profile of the Na0.44MnO2 (annealed at 800 ºC) cell at C/10, where 1C equals to 120 mAg-1. The material demonstrates a discharge capacity of 100 mAhg-1, which is comparable to materials reported from other synthesis methods.

References:

1. M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Advanced Functional Materials, Sodium-Ion Batteries, 23(8), 2013, 947-958.
2. V. Palomares, P. Serras, I. Villaluenga, K.B. Hueso, J. Carretero-Gonzalez, T. Rojo, Energy and Environmental Science, Na-ion batteries, recent advances and present challenges to become low cost energy storage systems, 5(3), 2012, 5884-5901.
3. F. Sauvage, L. Laffont, J.M. Tarascon, E. Baudrin, Inorganic Chemistry, Study of the insertion/deinsertion mechanism of sodium into Na0.44MnO2, 46(8), 2007, 3289-3294.
4. L.W. Zhao, J.F. Ni, H.B. Wang, L.J. Gao, RSC Advances, Na0.44MnO2-CNT electrodes for non-aqueous sodium batteries, 3(18), 2013, 6650-6655

Figure 1
Spinel LiMn2O4 Thin Films for 3 V Operating All-Solid-State Lithium Microbatteries
Authors: Bailly Nicolas , Mirvaux Boris , Boissel Jean-Marc , Porthault Hélène 
Published: February 2020

Nowadays, all-solid-state microbatteries have become a choice of alternative power source for microelectronic devices such as secured smart cards, RFID tags, stand-alone sensors, etc. In this context, low potential lithium-based systems suitable for microelectronic requirements have to be developed. Here, spinel LiMn2O4material, known for operating in the 4 V region, was investigated in the 3 V region.
Thin films were prepared using physical vapor deposition (RF-magnetron sputtering). SEM micrographs reveal a dense microstructure and a typical columnar growth. The as-deposited material appears to crystallize in a cubic spinel structure according to X-ray diffractograms. Atomic absorption spectroscopy shows a slight over-lithiation of the samples. Process parameters such as Ar/O2ratio and total pressure were optimized to improve electrochemical performances of the material.
First results were obtained in a coin cell configuration with an organic liquid electrolyte. Low crystallinity thin films elaborated with optimized conditions led to a good specific capacity of about 60 µAh.cm-².µm-1. A large 3 V plateau, which corresponds to the structural transformation from cubic spinel to tetragonal phase, can be observed after a low temperature post deposition heat treatment at 300°C in air (Fig. 1a, red curve).
LiMn2O4 thin films were then integrated in all-solid-state microbatteries using LiPON as solid electrolyte (Fig. 1b). The microbatteries integrating LiMn2O4thin films exhibit a good cycle performance.
The authors acknowledge ST-Microelectronics for the financial support.

Figure 1
Performance of a Mgs Battery Using Grignard Based Electrolytes
Authors: Perdue Brian Robert , Apblett Christopher Alan 
Published: February 2020

The lithium ion battery has revolutionized energy storage since its introduction to the commercial market in the early 90’s. Despite its impact, it can be argued that the lithium ion battery is reaching its limit in terms of energy density. In order to advance energy storage and move beyond lithium ion, new strategies must be considered such as a multivalent ion or a chemical conversion the cathode. One such system is the magnesium sulfur system which utilizes a chemically safe earth abundant multivalent magnesium metal anode with a high capacity (1675 mA/g) earth abundant sulfur cathode. One of the promises of using multivalent chemistry with sulfur cathodes is that the formation of polysulfides may be suppressed or eliminated as the multivalent sulfides compounds have low solubility in the solvent systems. In the current study full cells were constructed using a magnesium metal anode, a coated sulfur cathode, utilizing the well characterized Grignard based electrolytes (EtBuAlCl2)2- (dichloro complex, DCC) and second generation Mg(AlCl4-nPhn)2 (all phenyl complex, APC). Full cells were subsequently analyzed with slow scanning cyclic voltammetry (SSCV), galvanostatic charge/discharge, and post mortem EDX. SSCV results show electrochemical activity consistent with the formation of polysulfides for both APC and DCC with slight variations in performance between the two. Galvanostatic charge/discharge data shows an expected capacity loss between the first and second cycle, however an unexpected recovery of capacity as cycling continued with the capacity reaching 825 mAh/g at the 25th cycle. Full cell testing also demonstrated kinetic limitations as well as variations in performance between the two electrolytes consistent with SSCV results. Postmortem EDX was on each cell component and showed no evidence of polysulfides on the anode surface, and possible trace amounts of sulfur in the separator. EDX of the cathode showed evidence of a precipitated magnesium sulfur compound previously unreported. The absence of sulfur on the anode and separator coupled with the precipitated magnesium sulfur compound on the cathode suggests that polysulfides precipitate out in a magnesium system rather than shuttle as they do in the lithium system, presenting a possible solution to the issues of polysulfide formation.
Mesoporous Carbon Cathode in a Li-O2 Battery: Effect on Li2O2 Product Morphology and Recharge Potential
Authors: Dutta Arghya , Byon Hye Ryung 
Published: February 2020

One of the major challenges of lithium-oxygen (Li-O2) battery is high recharging overpotential, which is responsible for low stability of both non-aqueous electrolyte and carbon electrode, leading to serious side reactions. The fundamental reason for the high overpotential is very poor conductivity of solid Li2O2 as a discharge product, which requires further energy to be electrochemically decomposed (Li2O2→2Li+ + O2 + 2e–). Interestingly, the crystallinity and morphology of the Li2O2 profoundly influence on its conductivity, thus affecting the charging overpotential.1,2 The amorphous Li2O2 has much higher ionic and electronic conductivities compared to the crystalline Li2O2.1 In addition, the small size of Li2O2 with large contact area to the carbon electrode can aid in its smooth decomposition at low charging potential.2 Such type of Li2O2, which has been clearly observed in the presence of some solid-state metal/metal oxide promoters,3,4 is possibly attributable to the high O2 adsorption affinity of the promoters. Unlike these reports, we herein present the unique structure of Li2O2 using a promoter-free mesoporous carbon electrode, which greatly lowers the recharge potential. The mesoporous carbon of CMK-3 consisting of cylindrical-shaped pores with a pore diameter of ~3.5 nm was employed to the cathode (positive electrode) in the Li-O2 cell using 0.5 M LiTFSI in TEGDME. Strikingly, the CMK-3 based Li-O2 cell shows a very low recharge potential below 3.5 V until ~75% of recharge process. The pivotal reason for the decreased overpotential may be associated with an amorphous and flake-shaped Li2O2 vertically formed on the surface of CMK-3 during discharge, which are almost completely decomposed at the low recharge potential. This result is very distinguished from other carbon electrodes such as ketjen black (KB) carbon particle, multi-walled carbon nanotube (MWCNT) and LPC-80 consisting of spherical pores with a diameter of ~80 nm, where higher recharge potentials shown can be correlated with typical structure of spherical and thick Li2O2 particles. We propose that the surface structure of mesoporous carbon electrode is key to implant the Li2O2 flake while the effect of cylindrical pores within the CMK-3 may be negligible when considering low capacity (~1100 mAh/gcarbon) associated with a high surface area (~1500 m2/g). A detailed morphological and electrochemical analysis will be discussed in the presentation.

References

(1) Tian, F.; Radin, M. D.; Siegel, D. J. Chem. Mater. 2014, 26, 2952-2959.
(2) Dunst, A.; Epp, V.; Hanzu, I.; Freunberger, S.; Wilkening, M. Energy Environ. Sci.
2014,
7, 2739-2752.
(3) Yilmaz, E.; Yogi, C.; Yamanaka, K.; Ohta, T.; Byon, H. R. Nano Lett.
2013, 13, 4679-4684.
(4) Xu, J. J.; Wang, Z. L.; Xu, D.; Zhang, L. L.; Zhang, X. B. Nat. Commun.
2013, 4, 2438-2447.

Figure 1
Alternatives for Magnesium Metal Anodes? Intercalation Materials As Negative Electrodes for Rechargeable Magnesium-Ion Batteries
Authors: God Colin , Burrell Anthony K. , Ingram Brian , Kapper Katja , Koller Stefan , Lenardt Christian , Vaughey John T. 
Published: February 2020

The unabated demand of cost-effective and high performance battery systems compells research groups to look for further improvements of energy storage systems around the world. Lithium-ion batteries seem to be an appropriate solution for this energy issue, but on the other hand extraordinary breakthroughs within the next years are not to be anticipated. Furthermore, lithium-ion batteries still suffer from serious safety concerns. Considering properties such as a rather low reduction potential (-2.36 V vs. SHE), high specific capacity (3380 mAh/cc), low equivalent weight and moreover, sufficient safety due to a non-dendritic metal deposition, magnesium-ion batteries appear to be competitive to lithium-ion batteries [1].
Since organic, aprotic electrolyte systems create a passivation layer on the Mg metal surface preventing a reversible Mg-deposition and dissolution, corrosive electrolytes such as Grignard compounds have to be used [2]. However, research focuses on the development of Mg-battery systems with an operational voltage of 3V Grignard electrolytes do not provide. A strategy to achieve the ambitious 3V goal is the development of intercalation/insertion compounds such as tin or graphite and replacement of corrosive electrolytes by organic ones [3].
From literature it is well known that the Mg-intercalation into graphite is impossible showing even solvated intercalation [4, 5]. However, in this contribution we want to shed light on the intercalation behavior of Mg into graphite with a broad range of electrochemical and spectroscopical analysis methods showing a non destructive and reversible magnesiation and de-magnesiation of a common graphite electrode with organic, aprotic electrolytes (cf. figure 1, figure 2 and figure 3).

References:

[1] P. Saha, M.K. Datta, O.I. Velikokhatnyi, A. Manivannan, D. Alman, P.N. Kumta. Progress in Materials Science 66, 2014, 1-86.
[2] Z. Lu, A. Schechter, M. Moshkovich, D. Aurbach. Journal of Electroanalytical Chemistry, 1999, 203–217.
[3] N. Singh, T.S. Arthur, C. Ling, M. Matsui, F. Mizuno. ChemComm, 2012.
[4] M. Kawaguchi, A. Kurasaki. Chem. Commun., 2012, 48, 6897–6899.
[5] Y. Maeda, Ph. Touzain. Electrochimica Acta, 1988, 1493-1497.

Figure 1
Highly Concentrated Catholyte Based on Solvate Ionic Liquid for Flow Battery
Authors: Takechi Kensuke , Kato Yuichi , Hase Yoko 
Published: February 2020

Liquid based batteries, including a flow battery, have unique and significant benefits due to its simple structure and flexible handling of their liquid active materials as ‘electrochemical fuels’. In spite of this great ‘fueling’ capability, which may enable the rapid charging of electric vehicles, the energy density of the regular catholytes and anolytes is lower (<100 Wh/l) than that of the solid-state active materials used in regular batteries. A non-aqueous system is a simple and effective method of improving the discharging voltage more than 2 V, which is the limit of the aqueous system, coupling with highly negative anodes. The concentration of redox species in organic solvents is, however, generally lower than that in aqueous solutions and difficult to reach over 2 M with, at least, the same molar of supporting salt. It is important to note that stoichiometric couples of redox species and an appropriate salt is the minimum requirement for the liquid active materials because the valence of the redox species must be changed during discharging and charging and compensating ions must be present in the system. Moreover, the liquids should have a stable fluidic property without freezing or precipitation even in a low temperature range.
In this study, we report an innovative strategy to prepare the liquid active materials in order to increase their energy density. Our technology focuses on the
melting
of pure redox compounds to maximize their concentration instead of
dissolving
them in solvents. This simple yet challenging approach has been successfully realized using supercooled liquid technology by the combination of a specific plasticizing salt and a low melting point redox active compound. Such a supercooled liquid can be obtained by mixing of 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-methoxy-TEMPO, MT) and Li bis(trifluoromethanesulfonyl) imide (LiTFSI, LT) and stabilizing the mixture further below their melting points. The redox-active supercooled liquid exists in a highly stable liquid state over a wide temperature range that extends to below its normal melting points. The special properties of this supercooled liquid are due to the scientifically unique and rare solvation state known as a ‘solvate ionic liquid’, which is typified by a liquefied ion-pair stabilized by a neutral third compound. As a catholyte, the addition of an appropriate amount of solvent such as water helps to enhance the electrochemical advantage while maintaining the liquid’s supercooled nature, and a battery with a Li+ conducting architecture exhibits 93% electrochemical activity and 99% coulombic efficiency in the 1st cycle with an average discharge voltage of 3.6 V (Fig. 1). The catholyte also performed an energy density of 200 Wh/l, which is one of the highest values for catholytes reported to date with an organic redox compound.

Figure 1