bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variational Multiscale Modeling of Charge Transport in Li Metal Battery
Authors: Moradi Mohammadmoein , Liu Lin 
Published: February 2020

Battery performance highly depends on charge transport phenomena. The length scale of battery charge transport modeling is from nanometers to millimeters, therefore it makes the computational modeling difficult to accomplish. Moreover, the charge transport is well known at macro-scale and is easy to examine but there is difficulty in understanding the phenomena at micro-scale. Hence there is need for a framework that not only predicts the performance at macro-scale but also couples micro-scale details (e.g., microstructure and electrochemical reactions). The variational multiscale method (VMM) can be utilized as a paradigm for deriving models and numerical methods capable of dealing with multiscale charge transport phenomena [1]. The VMM can be applied to a broad range of problems and applications like complex electrochemical systems (e.g., Lithium batteries). VMM modeling is one of the essential tools to ascertain varied features of a problem concerning multiscale charge transport phenomena. In addition, VMM can be utilized to investigate continuum-scale systems with tracking detailed, electrochemical dynamics at the micro-scale [2]. Thus developing a VMM modeling framework to investigate the aforementioned problem is of much importance for obtaining reliable computational simulation results.
We will focus on building a link between battery micro-scale details and battery continuum level performance via VMM. The basic idea is to decompose the battery electrochemical modeling ODE/PDE solutions into two separate solutions including fine and coarse scale contributions. Fine scale equations will be solved with regard to coarse scale residuals and then the solution will be eliminated from coarse scale equations. Consequently, modified coarse scale equations which include the effects of fine scale can be obtained [3]. We will validate our model against Li metal batteries experimental studies on charge transport. Employing VMM, we can obtain charge transport at different levels and we expect the simulation and experimental data show better accuracy than traditional continue level simulations.
Reference
[1] T.J.R. Hughes, G.R. Feijόo, L. Mazzei, J. Quincy, Computer Methods in Applied Mechanics and Engineering,
3-24, 166 (1998)
[2] S. Lee, The University of Michigan, 2011
[3] M.G. Larson, A. Målqvist, Computer Methods in Applied Mechanics and Engineering, 2313-2324, 196 (2007)
A Novel Titanate As Anode Material for Sodium Ion Batteries
Authors: Ma Xuetian , Chen Hailong 
Published: February 2020

The concern regarding the availability and cost of lithium is raised owing to the fast growth of the markets for lithium ion battery (LIB) and other Li-chemistry based energy storage technologies, such as Li-Air and Li-S systems. Sodium ion battery (SIB) is considered as an alternative technology, due to the potentially low cost and abundance of sodium[1]. Yet many key components of SIBs, including cathode, anode, electrolyte, still require further improvement.
Here we report a new titanate compound as a promising anode material for sodium ion batteries. The compound was synthesized through solid state reaction. Powder X-ray diffraction (XRD) and refinement were applied to investigate the crystal structure. Electron microscopy was used to study the morphology. The electrochemical tests showed high first discharge capacity of >200 mAh/g and ~80 mAh/g reversible capacity in following cycles with good retention, as shown in Figure 1. Ex situ XRD was also performed for fully and partially discharged/charged samples to discover the cycling mechanism and possible reasons for the capacity decay of this material. The influence of synthesis conditions, including temperature, ball mill rate and carbon coating amount were also systematically investigated.

Figure 1
Improved Cycling Stability of Polypyrrole Coated NaTi2(PO4)3 As an Aqueous Na-Ion Anode
Authors: Mohamed Alexander I 
Published: February 2020

Aqueous sodium ion batteries offer an economic method for large-scale energy storage demanded by current sources of renewable energy. Although NASICON type NaTi2(PO4)3 is an attractive anode material with high capacity and a low redox potential allowing for high voltage cells, it suffers from considerable capacity fade when cycled slowly and deeply. In this work polypyrrole has been introduced as a coating for NaTi2(PO4)3 through a high-energy ball-milling process. When too thick of a coating was applied no redox reactions from the NaTi2(PO4)3 were visible due to the poor Na+ diffusion through the polypyrrole. The as coated composites containing 5wt% polypyrrole showed much better capacity retention compared to the uncoated material, retaining 57% of the initial discharge capacity after 50 cycles compared to the uncoated material retaining only 10% of the initial discharge capacity.
A Nanostructured Cathode Material with Varied Chemical Composition for High Energy Density Sodium Ion Batteries
Authors: Hwang Jang-Yeon , Myung Seung-Taek , Chung Kyung Yoon , Belharouak Ilias , Sun Y.-K. 
Published: February 2020

Lithium batteries currently dominate the secondary battery market because of their high energy and good power density.[1] Despite their feasibility, the mass production of such large-scale batteries would likely contribute to the future exhaustion of limited lithium resources. This concern has led us to look for alternative systems to replace current lithium-related chemistries. Because of sodium’s abundance in nature, sodium-based rechargeable batteries have recently received intensive attentions [2]Our prior works36,37, we suggested that the nanorod-structured full concentration gradient materials are beneficial in performing outstanding electrochemical properties and excellent safety in lithium-ion batteries system, because the dense rod assembly could minimize surface area contacting with electrolyte.[3] We introduce a new concept: a radially aligned hierarchical columnar structure (RAHC) in spherical particles with varied chemical composition from the inner end (Na[Ni0.75Co0.02Mn0.23]O2) to the outer end (Na[Ni0.58Co0.06Mn0.36]O2) of the structure.Using this concept, we suggest that an electrochemical reaction based on Ni2+/3+/4+ is readily available to deliver a high discharge capacity of 157 mAh (g-oxide)-1 (15 mA g-1), an excellent capacity retention of 80% (125 mAh g-1) during 300 cycles in combination with a hard carbon anode, and a reasonable rate capability of 132.6 mAh g-1 (1500 mA g-1, 10 C-rate). In addition, the RAHC electrode exhibits good temperature performance even at -20°C. The chemistry of the RAHC material, which utilizes the Ni redox reaction and minimizes the surface area contacting corrosive electrolyte, is responsible for the excellent electrochemical properties and the satisfactory thermal stability, which exhibits a main exothermic reaction at 293.5oC with low heat generation.

References

(1) Scrosati, B. & Garche, J. Lithium batteries: status, prospects and future. J. Power Sources 195, 2419 (2010).
(2) Stevens, D. A., Dahn, J. R. High capacity anode materials for rechargeable sodium-ion batteries. J. Electrochem. Soc. 147(4), 1271 (2000).
(3) Sun, Y.-K. et al. Nanostructured high-energy cathode materials for advanced lithium batteries. Nat. Mater. 11, 942 (2012).
Fabrication and Testing of Bulk-Type Solid State Batteries Based on a Garnet Oxide Electrolyte
Authors: Anandan Venkataramani , Drews Andy 
Published: February 2020

Li-ion batteries have become the preferred energy storage technology for automotive traction applications. Li-ion batteries have several advantages over competing technologies, including higher energy and power density. However, Li-ion batteries do not have sufficient energy density to provide the long (~500 mile) range that customers are accustomed to in a reasonable packaging volume. In addition, the flammable liquid electrolyte in Li-ion batteries presents safety concerns that must be carefully managed. Potential high-energy replacements for current Li-ion batteries are Li-S, Li-air and solid state batteries (SSB). Among these technologies, SSBs are the one technology offering both higher energy density and a significant reduction in safety risks over Li-ion batteries. In this study, the performance of a bulk-type SSB was evaluated. This cell was fabricated using lithium metal as anode, lithium lanthanum zirconium oxide (LLZO) as a solid electrolyte and LiCoO2 as cathode.
LLZO solid electrolyte was prepared using a solid state synthesis method. In this method, precursors were mixed well and calcined. Calcined LLZO was pressed into thick pellets, sintered and then sliced into thin (300 µm to 400 µm) sheets for cell testing. The measured ionic conductivity of these sheets was ~3 x10-4 S/cm. Composite cathode layers were fabricated by coating one side of several LLZO sheets with slurry containing LLZO and LiCoO2, which was dried and then sintered at various temperatures. After sintering, the other side of the LLZO sheet was attached to a lithium metal (anode) to form a solid state cell. The impedance contributions from the solid electrolyte, the anode/electrolyte interface and the cathode/electrolyte interface was determined for each cell using electrochemical impedance spectroscopy (EIS). EIS data showed that the main contribution to the cell impedances resulted from the cathode/electrolyte interfaces. Further performance and characterization studies are ongoing and its results will be presented at the meeting.
Structural Evaluation of Amorphous MoS3 Positive Electrode Active Materials in All-Solid-State Lithium Secondary Batteries
Authors: Matsuyama Takuya , Deguchi Minako , Hayashi Akitoshi , Tatsumisago Masahiro , Ozaki Tomoatsu , Mori Shigeo 
Published: February 2020

Sulfur is an attractive active material for positive electrode because sulfur has a high theoretical capacity. High capacity of the batteries can be achieved by using active materials with a large content of sulfur. Low electronic conductivity is a drawback of sulfur. We thus focus on a transition metal trisulfides such as TiS3 with high electronic conductivity. Moreover, amorphization of active materials is potentially capable of achieving higher capacity and cyclability because of open and random structure in amorphous materials. Recently, we have found that amorphous TiS3 prepared by ball milling had better cyclability than crystalline TiS3 [1, 2].
Very recently, we have reported that amorphous molybdenum trisulfide (a-MoS3) electrode active materials prepared by mechanical milling showed high reversible capacity (about 670 mAh g-1) for 60 cycles in the all-solid-state lithium batteries with Li2S-P2S5 electrolytes at room temperature [3]. However, the electrochemical reaction mechanism of a-MoS3 has not been identified yet. In order to improve the battery performance, it is important to understand the reaction mechanisms of a-MoS3 in the all-solid-sate lithium batteries. In this study, we investigated microstructures and morphologies of a-MoS3 electrodes before and after charge-discharge processes.

a-MoS3 was prepared by mechanical milling of the mixture of molybdenum metal and sulfur. The obtained active materials were applied as a positive electrode to all-solid-state cells with sulfide solid electrolytes. Structures and morphologies of a-MoS3 electrodes before and after charge-discharge tests were analyzed by XRD, XPS, SEM and HR-TEM.
The HR-TEM observations of a-MoS3 electrodes during the 1st discharge test revealed that the lattice fringes due to MoS2 layer structure disappeared gradually. After the 1st full discharge, the lattice fringes were not observed and the electron diffraction showed halo pattern. However, the lattice fringes like MoS2 were observed again after the 1st charge. These results of HR-TEM observations suggested that the reversible structural changes of a-MoS3 occurred. On the other hand, Li2S nano crystals were observed in HR-TEM image of a-MoS3 after the 10th discharge. The HR-TEM image after the 10th charge showed no lattice fringes of Li2S and MoS2. It is concluded that MoS3 after the 10th charge was completely amorphous.
Reference
[1] A. Hayashi, et al.,
Chem. Lett.,
41 (2012) 886.
[2] T. Matsuyama, et al.,
J. Solid State Electrochem.,
17 (2013) 2697.
[3] T. Matsuyama, et al.,
J. Mater. Chem. A, submitted for publication
Acknowledgment
This research was financially supported by ALCA-SPRING project.
High-Performance Non-Aqueous All-Organic Redox Flow Batteries
Authors: Wei Xiaoliang , Huang Jinhua , Zhang Lu , Xu Wu , Cosimbescu Lelia , Vijayakumar Murugesan , Liu Tianbiao , Liu Jun , Wang Wei , Sprenkle Vincent 
Published: February 2020

Redox flow battery has been widely considered as a promising large-scale stationary energy storage technology to stabilize the power grid and promote integration of renewables. The unique cell structure enables separation of energy and power thus offering tremendous design flexibility for different E/P applications. The limited voltage window in traditional aqueous flow batteries narrows down the intrinsic energy capacity. Therefore, nonaqueous redox flow batteries are being pursued because of the wider voltage window of nonaqueous electrolytes.
The current nonaqueous flow battery research is focused on the flow chemistry study and redox materials development.1 Among them, all-organic flow batteries is an important type and use organic electroactive materials at both positive and negative sides, taking advantage of the structural diversity and tunability of organic materials.2However, the current performance is limited by low redox material concentration, cell efficiency, cycling stability, and current density. Especially, development of suitable negative side redox materials is considered more challenging.
Here we report several high performance all-organic redox flow chemistries with cell voltages higher than 2V. These flow cell tests demonstrated remarkable cell efficiencies and high operational current densities that exceed those of most reported non-aqueous flow chemistries. A mechanistic study was carried out to gain fundamental understanding of performance degradation in these flow batteries, indicating that the chemical stability of the charged species in various supporting solvents and salts plays a critically important role in achieving decent flow cell cycling stability. This finding can serve as an important guidance for the selection and design of stable redox electrolyte systems.

Figure 1. (a) Cyclic voltammetry (CV) and (b) cycling capacity of an all-organic flow chemistry based on 9-fluorenone (negative) and 2,5-di-tert-butyl-1-methoxy-4-[2’-methoxyethoxy]benzene (positive).3

Figure 1
Evaluation of Carbon Foams and Membranes As the Cathode in Non-Flow Zinc Bromine Energy Storage Cells to Mitigating Liquid Bromine Convection
Authors: Biswas Shaurjo , Mohr Robert , Senju Aoi , Steingart Daniel A 
Published: February 2020

Zinc Bromine (Zn-Br2) secondary batteries have been extensively studied as a low cost, fully rechargeable, high density energy storage system. However, large scale and widespread commercial implementation of this battery technology has been retarded due to two key limitations [1]: i) self discharging of the cell due to Br2 (l) convection and diffusion through the liquid electrolyte towards the Zn anode. ii) shorting due to zinc dendrite formation after multiple cycles of the cell. Zn-Br2 flow-cells alleviate these limitations by adding Br2 (l) complexing agents, and flowing electrolyte to improve Zn plating, [2] respectively, at the cost of cell resistance, battery efficiency, size, and capital costs.

In this work, we address the Br2 (l) convection issue by designing a simple, low cost non-flow Zn-Br2 cell without the use of expensive complexing agents, via modification of the bromine cathodic electrode material composition and geometry. The Zn dendrite issue is addressed elsewhere [3]. We take advantage of the difference in density of the Br2 (l) (~3.1g/cc) and a 2M ZnBr2 electrolyte (~1.5 g/cc) to contain the liquid bromine below the cathode while cycling the cell. First, we demonstrate a thin membrane electrode composed of carbon black/graphite/PVDF having a density of 1.88 g/cc. The densities are matched such that the membrane electrode floats at the interface between the dense Br2 (l) and the electrolyte. During charging bromine forms and drops below the semi-porous membrane electrode while the cathode rises, reducing the anode-cathode spacing and, hence, the cell resistance. During discharge the Br2 (l) is prevented from convecting through the electrolyte by the physical membrane barrier, while allowing a small degree of diffusion. Second, we also demonstrate the use of highly conductive carbon foam bromine electrode, which selectively traps the non-polar Br2 (l) in its highly porous structure and thus addresses the bromine convection issue. The electrochemical characteristics of the non-flow Zn-Br2 cell based on both these bromine electrodes designs are discussed in terms of cell resistance, specific capacity, energy and coulombic efficiencies, energy storage capability and cycle life. The physical properties of the membrane and foam electrodes are analyzed using SEM, AFM and XRD.
Novel Long Cycle Life Room Temperature Sodium-Sulfur Batteries
Authors: Kohl Michael , Althues Holger , Kaskel Stefan 
Published: February 2020

Sulfur is natural abundant, cheap, non-toxic and has about seven times the electrochemical capacity of standard Li-ion battery cathode active materials (1672 compared to 250 mAh g-1), considering the conversion to S2-.[1] Due to likewise low costs and high reactivity towards sulfur, sodium poses as an optimal candidate for the cell reaction with sulfur.
Since the 1980s sodium sulfur batteries are used as commercial stationary energy storage systems. They consist of a sodium negative electrode, a sulfur positive electrode and a β''-alumina solid electrolyte in between.[2] Due to low ion conductivity of the materials, this battery type has to be heated to temperatures above 300 °C, resulting in safety challenges related to molten sodium and to increased operation costs. To take advantage of the low cost nature of sodium and sulfur, while avoiding its downsides, sodium-sulfur batteries driven at room temperature are aspects of today’s research. One of the largest differences is the use of liquid electrolytes in room temperature cells, in order to ensure sufficient ion conductivity.
However, first reports on room-temperature Na-S-cells indicate significant challenges related to a parasitic reaction of dissolved sodium polysulfide species limiting the coulomb efficiency, the specific capacity and cycle life of this system (so-called polysulfide shuttle).[3]
In this work, electrolyte composition, sulfur/carbon composite cathodes as well as anode materials were tailored to result in room temperature sodium-sulfur batteries with significantly reduced polysulfide shuttle. Electrolyte additives were identified being able to enhance the cell efficiency and increase the sulfur utilization through a redox mediation mechanism. This cell chemistry enables discharge capacities of 1000 mAh g-1 as well as improved capacity retentions exceeding values from recent literature.[3+4] Our results demonstrate the feasibility of stable and low cost sodium-sulfur batteries at room temperature enduring over 1000 reversible charge / discharge cycles.
References:
[1] X. Ji, L. F. Nazar, Nat. Mater., 2009, 8, 500–506.
[2] Z. Wen, Z. Lin, Solid State Ionics, 2008, 179, 1697–1701.
[3] H. Ryu, H.J. Ahn, J. Power Sources, 2011, 196, 5186–5190.
[4] I. Bauer, M. Kohl, H. Althues, S. Kaskel, Chem. Comm., 2014, 50, 3208-3210.

Figure 1
Preparation and Stability Research of Ago As Cathode Material
Authors: Yuan Yongqiang 
Published: February 2020

Silver-zinc battery (AgO/Zn) is regarded as an energy storage system with advantages of high energy density, high power density and superior rate capability when compared with Ni-MH and lithium battery systems. Due to its relatively high cost, AgO/Zn batteries are widely employed in the field of underwater devices, fish torpedo and aerial/space applications. nanoscaled AgO with high purity was synthesized by a chemical precipitation method, and found this method suited to industrialized production. the electrode offers a discharge voltage plateaus of 1.3-1.58V, a discharge capacity of above 393 mAh·g−1 at 8 C rate ,and an exciting specific power density much higher than the current level for existing secondary batteries and super capacitors.
As a cathode material for AgO/Zn battery, AgO suffers severely from its poor thermal stability. During long-term storage, AgO decomposes and generates Ag2O and Ag, which in return fasten the decomposition process of AgO. As a result, decomposition issue for AgO even occurs at room temperature. To the best of our knowledge, there is few study regarded to the thermal stability of AgO and no mature fabrication process for AgO has been reported. Na2SiO3, well-know inhibiter, is widely used in alkaline Zn-MnO2 battery to improve stability of the battery. However, there is no systematic investigation of using Na2SiO3 as stability agent in AgO/Zn system. Herein, the effects of Na2SiO3 on the thermal stability and electrochemical performance of AgO are elucidated.
Through aging treatments, it is concluded that with the introduction of Na2SiO3, the decomposition degree of AgO at room temperature has been reduced to some extent. However, the decomposition temperature of AgO remains unchanged. On the other hand, electrochemical performance of AgO/Zn battery is degraded with addition of Na2SiO3 in the cathode material due to the poor conductivity of Na2SiO3. The results showed that 10 min later after the injection of KOH electrolyte into the cell model, Na2SiO3 mainly influences discharge voltage at early stage when discharging the cell at 4 C with voltage cut-off at 1.0 V. The discharge voltage drop at early stage increases significantly with increasing the amount of Na2SiO3. The open circuit voltage of the AgO with 2wt% Na2SiO3 as cathode was 1.6 V and the voltage suddenly dropped to 1.18 V after the current was applied. The discharge voltage for the AgO with 10.7wt% Na2SiO3 as cathode drastically dropped to 0.2 V under the same test condition. Interestingly, the discharge voltage turned out to be almost identical after discharging for 20 s for all the cells with different weight ratio of AgO as cathodes. These results indicates that the introduction of Na2SiO3 in the AgO cathode mainly influence solution equilibrium.