bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrafine Nb2O5 Nanocrystal Coating on Reduced Graphene Oxide As Anode Materials for Sodium Ion Battery
Authors: Yan Litao , Chen Gen , Luo Hongmei
Published: February 2020

Sodium ion battery (SIB) is a promising candidate for large-scale and practical application because of its lower costs and widespread of sodium resource.1 However, for SIBs, the intrinsic difference between sodium and lithium (ca. 55% larger and 330% heavier) lead to slower kinetics and lower energy densities.1 Nevertheless, it is reported that the enhance SIBs performance could be obtained by introducing the proper sodium host.2 For example, recent advances indicated that the ordered mesoporous Nb2O5-C delivered a reversible capacity of ~175 mA h/g and excellent cycle stability (up to 300 cycles).3 However, the low rate performance (<100 mA h/g at rate of 1A/g) cannot meet the requirements of fast charge-discharge electrochemical devices.

In this work, ultrafine Nb2O5 nanocrystal/reduced graphene oxide (Nb2O5/rGO) was demonstrated as a promising anode material for sodium ion battery with high rate performance and high cycle durability. The Nb2O5/rGO was synthesized by controllable hydrolysis of niobium ethoxide and following treated at high annealing temperature in forming gas. Transmission electron microscopy (TEM) showed that ultrafine Nb2O5 nanocrystal with average particle size of 3 nm was uniformly deposited on rGO. Highly conductive rGO network and ultrafine Nb2O5 not only can enhance charge transfer and buffer the volume change during sodiation/desodiation process, but also could provide more active surface area for sodium ion storage, resulting in superior rate performance and cycle performance. XPS and XRD analyses revealed that the sodium ion storage mechanism in Nb2O5 could be accompanied with Nb5+/Nb4+ redox reaction and the ultrafine Nb2O5 nanocrystal provide more surface area to finish the redox reaction.

 

Reference:

1. N. Yabuuchi, K. Kubota, M. Dahbi and S. Komaba, Chemical Reviews, 2014, 114, 11636-11682.

2. Y.-U. Park, D.-H. Seo, H.-S. Kwon, B. Kim, J. Kim, H. Kim, I. Kim, H.-I. Yoo and K. Kang, Journal ofthe American Chemical Society, 2013, 135, 13870-13878.

3. H. Kim, E. Lim, C. Jo, G. Yoon, J. Hwang, S. Jeong, J. Lee and K. Kang, Nano Energy, 2015, 16, 62-70.
Divalent Tin Oxide (SnO) Carbon Composite As Superior Anode in Sodium-Ion Batteries
Authors: Zhou Dehua , Johnson Christopher
Published: February 2020

In the sodium system, perhaps the greatest technical hurdle to overcome is the lack of a high-performance anode material, which has good capacity, is easy to synthesize, safe, non-toxic and is low cost. The opportunity in this area is to develop a new anode material that meets all of these criteria. To date there are a handful of examples in the literature that show the chemistry and battery performance of ambient temperature sodium ion battery anodes. Most of these are various carbon materials, Sn, Sb or SnSb, intermetallics, and sodium titanium oxides, but for one reason or another many of these fall short of all the attributes needed.

Our approach is to develop novel oxygen-containing intermetallic nanocomposite anodes with a high surface area/volume ratio that includes a specially tailored cocktail of individual elements and intermetallic phases to enable sequential electrochemical reactions that are designed to reduce the volume expansion while increasing the volumetric capacity. In this case we have been developing a carbon composite consisting of semi-conducting divalent tin oxide (SnO). In the case of a conversion reaction and then sodiation of expelled Sn, then the irreversible capacity will be lower than for SnO2 due to the smaller amount of oxygen in the system. In fact we have synthesized an attractive anode system for sodium-ion batteries (SIBs) that consists of SnO_C made by high-energy ball milling simply carbon with commercially available SnO. Figures 1a and 1b show the voltage profiles of the first two cycles, and the capacity with cycle numbers. The results demonstrate the viability of this material as an anode for SIBs. This material and its detailed in operando X-ray characterization will be discussed at the talk.

Figure 1. (a) First two voltage profiles of Na/SnO_C composite SIB anode. Note the low first cycle irreversibility capacity loss; (b) capacity and coulombic efficiency over 35 cycles.

Acknowledgements

This work is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Figure 1
High Performance Magnesium Ion Electrolytes
Authors: Herb Jake Tompkins , Nist-Lund Carl , Arnold Craig B.
Published: February 2020

Magnesium-ion based battery chemistries have been the subject of intense research because of the inherent high energy density of metallic magnesium anodes. One of the biggest complications that has limited the progress in this area is the development of electrolytes that facilitate the reversible deposition of magnesium metal. Current state of the art electrolytes are based on Grignard-derived magnesium compounds paired with Lewis acids such as aluminum chloride. A few notable exceptions utilize carborane structures as anions, which enable reversible electrochemistry. The presence of chloride ions in many electrolyte solutions has proven to be problematic because they cause pitting and corrode parts commonly used in coin cells. As such, it is imperative that researchers identify pathways that can result in halide-free electrolyte solutions. We have developed a new paradigm for magnesium ion electrolytes, utilizing a robust synthesis pathway that incorporates common reagents. The electrolyte has a large voltage window on stainless steel and aluminum (4-5 V vs. Mg), high conductivity (comparable with lithium ion electrolytes), and near unity Coulombic efficiency. We will discuss characterization of the electrolyte, identity of solution species, and promising methods of modifying the electrolyte for improved figures of merit.
Diffusion Measurements of Mg in High Capacity Thiospinel MgxTi2S4
Authors: Bonnick Patrick , Sun Xiaoqi , Nazar Linda F
Published: February 2020

The demand for smaller batteries capable of storing the same amount of energy as conventional Li-ion technology has led to the pursuit of several new technologies including rechargeable Mg batteries. Mg metal is attractive as a negative electrode material because it has a higher volumetric capacity density (3833 mAh/mL) than Li metal (2062 mAh/mL), is the 8th most abundant element in the earth’s crust, is safe to handle in ambient atmosphere, and can be electrodeposited (charged) without the formation of dendrites.1 The seminal work by Aurbach et al. in 20002 established an electrolyte and a positive electrode material, the Chevrel phase (Mo6S8), that was paired with Mg metal to form the first rechargeable Mg battery.

Mg2+ intercalation in host materials is more difficult than that of Li+ or Na+, displaying lower ion mobility in solid oxide hosts3 and a probable higher desolvation energy penalty.4 No further positive electrode materials with both notable capacity and cycle life have been demonstrated since the Chevrel phase, until now. In this presentation, we will demonstrate that the thiospinel Ti2S4 reversibly intercalates Mg2+ with a 2ndcycle capacity of about 165 mAh/g, which drops to only 140 mAh/g after 40 cycles at C/10 as shown in Figure 1.

Of crucial scientific importance is that Ti2S4 provides a second example of a material that supports facile Mg2+ diffusion, which could help elucidate why Mg2+ intercalation is so difficult in other potential cathode materials. In exploring Mg2+ diffusion, the first step is to measure the chemical diffusion coefficient, D. The galvanostatic intermittent titration technique (GITT)5 is a versatile method of carrying this out for an intercalant like Mg2+ if a reliable cell can be constructed that has a long enough diffusion length to produce a linear potential vs time response reflecting Fick’s laws of diffusion. Figure 2 shows a typical GITT experiment on thiospinel MgxTi2S4, which displays the required potential vs time response. This talk will elaborate on the results of the diffusion measurements we have performed and compare those results to theory.

References

J. Muldoon, C. B. Bucur, and T. Gregory. Chem. Rev.
114, 11683-11720 (2014).

D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich and E. Levi. Nature
407, 724-727 (2000).

E. Levi, Y. Gofer, and D. Aurbach. Chem. Mater.
22, 860-868 (2010).

L. F. Wan, B. R. Perdue, C. A. Apblett and D. Prendergast. Chem. Mater.
27, 5932-5940 (2015).

W. Weppner and R. A. Huggins. Solid-State Science and Technology
124, 1569-1578 (1977).

Figure 1
First-Principles Screening and Evaluation of Sulfide Compounds for Multivalent Battery Cathode Applications
Authors: Liu Miao , Rong Ziqin , Canepa Pieremanuele , Malik Rahul , Jain Anubhav , Ceder Gerbrand , Persson Kristin A
Published: February 2020

The rapid growth of portable consumer electronics and electric vehicles demands new battery technologies with greater energy stored at a reduced cost. Energy storage solutions based on multivalent metals, such as Mg, could significantly increase the energy density as compared to lithium-ion based technology. In this work, we use recent advances in high-throughput first-principles calculations to systematically evaluate the performance of a group of 3d transition-metal sulfide compounds for multivalent cathode applications. We estimate the insertion voltage, capacity, thermodynamic stability of charged and discharged states, as well as the intercalating ion mobility and use these properties to evaluate promising directions. From our calculations, we identified sulfide compounds that exhibit improved Mg2+ mobility with feasible low diffusion activation energy; lower than their oxide counterparts, however the improved mobility comes at the expense of lower voltage and thereby lower theoretical specific energy. We also identified a Ca2+ intercalating sulfide compound which exhibits a low diffusion activation barrier of ~500 meV and a voltage of ~2V, revealing a potential cathode for use in Ca ion rechargeable batteries. We also present several general trends and design insights extracted from our evaluation for this category of materials.
Facile Chemical Routes to Assess the Feasibility of Electrode Hosts for Multi-Valent-Ion Insertion/Extraction
Authors: Manthiram Arumugam , Kaveevivitchai Watchareeya
Published: February 2020

The drive to increase the energy density, lower the cost, and enhance the safety is creating enormous interest in rechargeable battery systems based on multi-valent cations, such as magnesium, zinc, and aluminum as these metals are relatively abundant and inexpensive and offer superior safety compared to lithium when exposed to air and cycled in the cell. However, identifying potential electrode hosts for reversible reaction of multi-valent ions is a great challenge. Also, the lack of well-established electrolytes to assess the true behavior of the electrode materials for multi-valent working ions further hampers the efforts. To overcome this difficulty, this presentation will focus on the development and use of simple, facile chemical methods to assess the reaction/insertion/extraction of multi-valent ions into potential hosts without requiring the electrolytes for multi-valent working ions or the assembly of the electrochemical cells. For example, extraction of multi-valent ions from potential electrode hosts with nitronium tetrafluoroborate in acetonitrile medium and insertion of multi-valent ions into potential hosts with a microwave-assisted solvothermal process will be presented. Use of these insertion/extraction methodologies with example systems based on both close-packed structures and open structures will be presented. Particularly, the challenges associated with close-packed systems such as spinel hosts due to the electrostatic repulsion between the working multi-valent ions and the highly-charge host transition-metal ions will be demonstrated in comparison to the lithium analogues. Furthermore, tuning the reducing power during the microwave-assisted solvothermal process by choosing appropriate solvents will be highlighted. Based on the chemical methods presented, the identification of a few new hosts for reversible reaction of multi-valent ions will be presented.
Structural and Chemical Synergistic Encapsulation of Polysulfides Enables Ultralong-Life Lithium-Sulfur Batteries
Authors: Wang Xiaolei , Li Ge , Li Jingde , Chen Zhongwei
Published: February 2020

The fast depletion of fossil fuels and deterioration of environment have led to increasing demand for renewable energies and efficient energy storage technologies. Lithium-sulfur (Li-S) batteries have been regarded as one of the most promising high-energy power sources in broad applications ranging from electric vehicles to large-scale grid energy storage. Li-S batteries deliver a theoretical energy of 2600 W h kg-1 that is an order of magnitude higher than that of the current lithium-ion batteries (LIBs), and utilize naturally abundant sulfur as the cathode material which significantly reduces the cost. The major challenge for the practical implementation of Li-S batteries resides in the dramatic capacity decay. The intermediate lithium polysulfides (Li
x
S
n
, 3≤n≤8) formed during cycling dissolve in the liquid electrolyte, migrate through the separator, and deposit on Li metal anode, causing “shuttle effect”. In addtion, the utilization of the active material is strongly hampered by the intrinsic insulating of S and its discharge product Li2S, leading to a low capacity and poor rate capability. Furthermore, the S cathode suffers from the volume variation (~80%) during lithiation/de-lithiation, causing the loss of electrical contact and the structure instability.

Herein, we demonstrate an innovative strategy to efficiently entrap Li
x
S
n
from synergistic effect of structural restriction and chemical encapsulation using metal oxide-decorated hollow sulfur spheres. The significance of this strategy lies in that we purposely design a material architecture with both structural and chemical encapsulation effect, and that the material architecture provides a prolonged cycling stability. MnO2 is selected as a model and the MnO2 nanosheets-decorated hollow S spheres (hollow S-MnO2) nanocomposites are achieved through a facile synthesis. The nanocomposites with unique structure possess several features favoring highly stable S electrodes: i) the hollow spheres with inner void space not only alleviate the volume expansion of S on lithiation but also structurally restrict soluble Li
x
S
n
within the spherical structure; ii) the decorated MnO2 nanosheets with large surface area efficiently and chemically minimize the polysulfides dissolution by forming strong bonding; iii) the small dimensions of hollow S-MnO2 nanocomposites facilitate both ion and electron transport, leading to a better utilization of the S. This design presents a new strategy to prevent loss of polysulfides by structural and chemical dual-encapsulation, and can be expanded to other metal oxides or metal hydroxides. The unique material architecture enables high-performance S cathodes with high capacity, high sulfur loading and extremely low capacity decay of only 0.028% per cycle over 1500 cycles at 0.5 C-rate.

Figure 1
Extending Cycle Life of Lithium-Sulfur Cells Using a Flexible and Selective Lithium-Ion Conducting Membrane
Authors: Moy Derek , Narayanan S. R.
Published: February 2020

Lithium-sulfur chemistry has the potential to overtake Lithium-ion battery technology with its high theoretical specific capacity at 1675 mAh/g and energy density at 2600 Wh/kg. These properties coupled with the low cost and natural abundance of sulfur makes the lithium-sulfur battery attractive as a cost-effective and high energy density battery solution. However, the large scale deployment of these lithium-sulfur batteries have been severely limited by their poor cycle life. The typical lithium-sulfur cell loses over 20% of its initial capacity within its first 100 cycles. One of the major causes of these capacity losses is a parasitic reaction known as the polysulfide shuttle.

The polysulfide shuttle is present in all lithium-sulfur cells due to the inherent solubility of the higher order polysulfide discharge products, S8
2-, S6
2-, and S4
2-. These soluble polysulfides constantly shuttle between the sulfur and lithium electrodes. When these species contact the negative lithium electrode, they are reduced to shorter chain polysulfides that must shuttle back towards to sulfur electrode to be re-oxidized. However, some polysulfides such as S4
2- are reduced to insoluble S2
2-on the surface of lithium electrode, resulting in an irreversible capacity loss. Inhibiting the polysulfide shuttle is necessary to protect the lithium electrode as well as to prevent capacity loss.

We demonstrate the ability to inhibit the polysulfide shuttle using a lithium-ion selective membrane. The membrane is a thin, flexible, and non-porous barrier layer that restricts all soluble polysulfide species at the sulfur electrode and prevents their diffusion towards the lithium electrode. The membrane is ionically conducting to allow transport of lithium ions necessary for charge and discharge processes. The membrane remains inert to polysulfide species at all operating voltages and presents a barrier to growth of lithium dendrites and catastrophic failure. In a cell configuration, the membrane is electronically isolated from the two electrodes by using porous separator layers placed on either side of the membrane.

We tested the lithium-ion selective membrane in 2032-type coin cells using sulfur-carbon composite positive electrodes, lithium foil negative electrodes, and 1 M LiTFSI electrolyte. The performance of cells containing the lithium-ion selective membrane was compared to cells without the membrane as well as to cells with 0.25 M lithium nitrate (the state-of-the-art polysulfide shuttle suppressing additive). We analyzed the performance of these cells using galvanostatic cycling, electrochemical impedance spectroscopy, and direct shuttle current measurements1. We found that the lithium-ion selective membrane improves the cycle life of lithium-sulfur cells through inhibition of the polysulfide shuttle.

References

1. D. Moy, A. Manivannan, and S. R. Narayanan, J. Electrochem. Soc., 2015, 162, A1-A7

Figure 1
Growth and Electrochemical Characterization of Sea Urchin Shaped α-MnO2/RuO2 Mixed Oxides for Cathode Catalyst Application in LithiumOxygen Battery
Authors: Moon Kwang Uk , Park Hyosoek , Jang HoSaeng , Arul Anupriya , Christy Maria , Oh Mi Young , Nahm Kee Suk
Published: February 2020

For the further advancement of lithium air battery, the design of a new promising bifunctional electrocatalyst is necessary to improve oxygen reduction and evolution reactions (ORR and OER) kinetics during discharge and recharge processes. In this work, three dimensional (3D) α–MnO2/RuO2 mixed oxides were designed and synthesized using simple hydrothermal method. The morphology of the mixed oxides changed from sea urchin shaped nanostructures to nanospheres with the increase of RuO2 content in the mixed oxides. The growth mechanism of the mixed oxides have been studied by analyzing their step by step growth and development through various characterization techniques such as x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), cross sectional TEM and electron dispersive spectrum, etc. It was found that α–MnO2 and RuO2 significantly served as oxygen reduction and evolution reaction catalysts, respectively, indicating that the mixed oxide is suitable as bifunctional catalyst for Li–O2 battery. Among the four different α–MnO2/RuO2 composition ratios, (75:25) appeared to be the optimum ratio for the mixed oxides with superior activity for both ORR and OER. The superior performance of (75:25) ratio can be attributed to its structural and compositional design which aid in the better catalytic performance. When applied in Li–O2 battery system, the (75:25) ratio exhibited excellent performance with maximum capacity of >8100 mAh/g, high coulombic efficiency and cyclability.
Exploring the Electrochemical Reaction Mechanism of Carbonate Oxidation in Li-Air/CO2 Battery through Tracing Missing Oxygen
Authors: He Ping
Published: February 2020

As energy storage systems with great prospects, both Li-air and Li-CO2 batteries suffer from the low energy efficiency and poor cycle performance caused by the accumulation of Li2CO3 during cycling. Therefore, a complete electrochemical decomposition of Li2CO3 during charging will greatly improve the performance of Li-air and Li-CO2 batteries. However, our understanding of the electrochemical decomposition mechanism of Li2CO3 is very limited. In this work, we investigated the electrochemical reaction mechanism of Li2CO3 oxidation. During the charging process of Li2CO3 electrode, CO2 was detected as the main charging product while at the same time no gaseous O2 was released. With the help of isotopic tracing and GC-MS method, we were able to eliminate the possibility of the direct self-decomposition reaction of Li2CO3 as well as the reaction between Li2CO3 and carbon. Further experiments illustrated that superoxide radicals and dissolved oxygen generate during the charging process of Li2CO3 and will lead to electrolyte solvent decomposition. Combining the above results, we suggest that the decomposition mechanism of Li2CO3 can be described as follows: Li2CO3 decomposes into CO2, superoxide radicals and O2(formed by part of the superoxide radicals). The O2 and superoxide radicals are consumed by the further reaction with tetraglyme electrolyte solvent and thus fail to be detected.
Modeling the Thermodynamic and Kinetic Effects on the Electrochemical Performance of Planar Na-NiCl2 Batteries
Authors: Kim Chang-Soo , Xu Yihan , Li Guosheng , Park Yoon-Cheol , Jung Keeyoung
Published: February 2020

Na/metal chloride batteries (i.e., Na-NiCl2 or Na-FeCl2 batteries) possess a number of excellent properties including high safety and stability, high energy density, high voltage, no self-discharge, and good cycle life. Relying on these advantageous features, these Na/metal chloride secondary cells have a high potential for applications of transportation and vehicles as well as the advanced stationary energy storage systems (ESS). In these Na/metal chloride batteries, the electrochemical performance is largely determined by the thermodynamics and kinetic reactions in the cathode area comprised of NaCl particles, Ni/NiCl2 and/or Fe/FeCl2 powders, NaAlCl4 secondary electrolyte (i.e., catholyte), and various additives. During the charge-discharge process, complicated electrochemical reactions will occur in this cathode of the cell, including ionic diffusion of Na+ through NaAlCl4 catholyte driven by the chemical potential and the electric potential gradients, dissolution/coarsening of NaCl particles, and precipitation/decomposition of NiCl2 or FeCl2.

The presentation introduces a continuum computational model to capture the quantitative effects of reaction thermodynamics and transport kinetics on the electrochemical performance of Na/metal chloride batteries with a Na-NiCl2 cell chemistry. The computational model was developed using a commercial COMSOL multi-physics software package. The model was applied to characterize a novel planar cell, which was designed adopting a disc shaped beta-alumina solid electrolyte (BASE) instead of a conventional cloverleaf shaped BASE. The planar cell geometry was intended to lower the cell operation temperature by optimizing the cell performance. In this multi-physics computational model, relevant physicochemical materials properties of active materials have been incorporated. The cell voltage was calculated using the Butler-Volmer kinetic equation and the temporal volume change of the active materials was computed based on the local current densities. The computation results were used to quantitatively investigate the effects of (1) cell operation temperature, (2) cathode active materials to catholyte ratio, and (3) cell dimension on the charge-discharge characteristics of the planar Na-NiCl2 cell. Especially, the combined effect of operation temperature and cell size on the cell performance was of special interest. It turns out that the electrochemical performance of the Na-NiCl2 cells is highly dependent on the cell operation temperature to show reduced cell voltages with decreased operation temperatures.
Oxygen Selective Membrane for Lithium Air Batteries
Authors: Cao Lujie , Lv Fucong , Liu Ying , Wang Wenxi , Huo Yifeng , Lu Zhouguang
Published: February 2020

Lithium air batteries have attracted great recent research interest due to their much higher energy density than that of the currently used Li-ion batteries (3600 Wh kg-1 vs 300 Wh kg-1). However, one of the most critical issues for practical application of Li-air batteries was the contamination of moisture and CO2 from the air. Here we report a high performance O2 selective mixed matrix membrane based on the metal organic framework (MOF) nanocrystallines of CAU-1-NH2@PDA (CAU = Christian-Albrechts-University) and the polymer of polymethylmethacrylate (PMMA). CAU-1-NH2 is a stable metal–organic framework [Al4(OH)2-(OCH3)4(H2N-bdc)3]·xH2O, containing the new Al-containing octameric brick {Al8(OH)4(OCH3)8}12+ (Fig. 1). It has been found that the obtained mixed matrix membrane (MMM) possessed several advantages including high surface area, controlled porosity, adjustable chemical functionality, high affinity for specific gases and compatibility with polymer chains, making it attractive candidate for selective gas separation. Specifically, the functional group –NH2 in the MOF, –OH in the polydopamine molecule, and the –C=O in the PMMA would preferably interact with CO2 molecule. Also, the intrinsic hydrophobic behaviour of the PMMA polymer can favourably prevent the intrusion of moisture (Fig. 1). These two favourable effects guaranteed the Li-air cell working very stable under ambient atmosphere with very high relative humid (30%) by repelling CO2 and moisture from the air. Evidently, the developed mixed matrix membrane based on CAU-1-NH2@PDA and PMMA polymer opens the way to develop novel air-permeable membrane for real Li-air batteries applied in ambient conditions rather than in pure oxygen (Li-O2) conditions.

Figure 1
Synthesis and Electrochemical Activity of Sodium Titanium Phosphate for Sodium Ion Battery
Authors: Kim Doyoub , Park Heetaek , Kang Byoungwoo
Published: February 2020

Lithium ion batteries have become the very foundation of today’s wireless technology especially mobile electronic devices. However, there has been a growing concern on its scarcity and rising price1. At the same time, large scale applications, electric vehicle and energy storage system, brought upon the needs for low cost and environmentally clean battery system. In this context, sodium ion batteries meet the needs since it is naturally abundant and economic feasible.

Identical to the research on negative electrode materials for lithium ion batteries, much of that for sodium ion batteries have been focused on carbonaceous materials, oxides and polyanionic compounds2. Among these categories, negative electrode materials consisting of polyanionic compounds especially phosphates become of great interest because of their thermal and structural stability3.

In this talk, we report sodium titanium phosphates that can be usable for anode materials of sodium ion batteries with either aqueous electrolyte or non-aqueous electrolyte. Depending on the synthesis conditions of this material, it has two different polymorphs. While one is electrochemically active, the other isn’t. Furthermore, we will present the effect of two polymorphs’ structure on the materials’ electrochemical activity.

Reference

J. M Tarascon, M. Armand, Nature 2001, 414, 359

N. Yabuuchi, K. Kubota, M. Dahbi, S. Komaba, Chemical Reviews, 2014, 114, 11636-11682 

G. Hautier, A. Jain, S. P. Ong, B. W. Kang, C. Moore, R. Doe and G. Ceder, Chem. Mater. 23, 3495-3508, 2011.
Theoretical Overpotentials for Metal Anodes
Authors: Nagy Kyle Steven , Kazemiabnavi Saeed , Siegel Donald J
Published: February 2020

Metals, especially those with low standard electrode potentials, are attractive candidates for use as anodes in rechargeable batteries because of their generally higher capacities compared to intercalated graphite. In order to be practical, these metals should efficiently plate and strip with low overpotentials during battery cycling. In general, overpotentials have thermodynamic and kinetic contributions. An important thermodynamic contribution arises from heterogeneity in the [de/ad]-sorption energy due to inequivalent reaction sites on the electrode surface. Here we systematically calculate thermodynamic overpotentials for plating and stripping on seven metal electrodes (Li, Na, K, Mg, Ca, Zn, and Al) of relevance for “beyond Li-ion batteries.” For all metals the potential limiting steps are terrace reactions, corresponding to deposition of atoms onto an otherwise empty terrace during plating, or creation of a vacancy in a terrace (pit formation) during stripping. These reactions may be considered as nucleation events, with the added/removed adatom as the critical nuclei. Coordination number of the metals correlates with overpotential: alkali metals with BCC coordination exhibit amongst the most efficient plating and stripping thermodynamics. In agreement with experiments, the cycling of Ca anodes are predicted to be highly inefficient.
All-Solid-State Li Battery with Sulfur Composite Cathode
Authors: Choi Han Ul , Lim Hyung-Tae
Published: February 2020

All-solid-state batteries were fabricated using lithium silicide anodes (Li4.4Si), sulfide-based glass electrolyte (Li2S-P2S5), and sulfur composite cathodes. Sulfur cathode was prepared by various methods; ① Hand mixing by mortar, ② Ball milling at 370rpm for 15min and ③ Secondary ball milling(planetary ball mill) at 700rpm for 10min after completing the method ②. It was found that the method ② improved distribution of sulfur, carbon and solid electrolyte(S.E) particles. The method ③ increased interfacial area(reduced particle size) as well as improved distribution of electrode component particles. BET(Burnauer-Emmett-Teller) adsorption, EDS(Energy Dispersive Spectroscopy) mapping and GITT(Galvanostatic Intermittent Titration Test) were conducted on the cell with three types of composite cathode, to investigate the effect of preparation methods on particle size(S, C, S.E), particle distribution and interfacial area, respectively. This effect was reflected in charge-discharge tests on the full cell with the method ③ cathode, resulting in higher capacities. Thus, the present work indicates why preparation method of sulfur composite electrode layers is a critical factor in determining the performance of all-solid-state Li-S batteries.
Novel Sodium-Rich Anti-Perovskites Via Conventional Sintering and Spark Plasma Sintering
Authors: Nguyen Han , Hy Sunny , Wu Erik , Deng Zhi , Yersak Thomas A. , Ong Shyue Ping , Meng Ying Shirley
Published: February 2020

We experimentally investigated the effects of two processing techniques: conventional cold pressing and spark plasma sintering, on Na3OBr, a sodium-rich antiperovskite solid-state electrolyte. We demonstrated that the electrolyte can be synthesized via a single-step solid-state reaction from readily available sources. We compared the differences between CP and SPS processing using XRD, SEM, and EIS and determined that SPS reduced the grain boundary impedance contribution by three orders of magnitude, which translated into an increase in the overall Na ionic conductivity. Additionally, the SPS sample had activation energy of 0.837 eV, lower than the 1.142 eV of the CP sample. DFT was also undertaken to gain insight on the Na ion conduction behavior of Na3OBr.

Figure 1
The Effects of Electrolyte Variations on the Oxygen Efficiency in Lithium Air Batteries
Authors: Ryu Kyoung Han , Kim Won Keun , Seo Samuel , Lee Ho-Teak
Published: February 2020

While the existing lithium-ion batteries have been extensively used in electric vehicles (EVs), their limited specific energy restricts the driving range. In this context, rechargeable lithium air (or Li-O2) batteries have attracted considerable interest in recent years as a potential power source for EVs, owing to their high theoretical specific energy. A typical non-aqueous lithium air battery consists of a porous air electrode, a lithium metal anode, and electrolyte containing lithium salt. The electrolyte is generally regarded as a critical component as it is directly related to the stability and the performance of a lithium air battery. While physicochemical properties of potential electrolytes are often discussed, the ability of electrolyte to utilize the oxygen during reversible charge/discharge cycle is rarely explored. In fact, previously reported gas analysis indicated low current efficiency for O2 evolution during charging (Li2O2 → 2Li+ + O2 + e-), accompanied the evolution of byproduct gases such as H2 and CO2.1-2 Furthermore, the O2 revolution (therefore, rechargeability) seemed highly dependable on the choice of electrolyte.

In this work, we investigated the oxygen efficiency during discharge/charge cycle in lithium-air using differential electrochemical mass spectrometry (DEMS). We explored various electrolytes that have the potential to prompt reversible electrochemistry in Li-O2 battery. In addition to this, the effect of a catalyst and lithium salt variation on the O2 evolution was investigated.

1) B. D. McCloskey, D. S. Bethune, R. M. Shelby, G. Girishkumar, and A. C. Luntz, J. Phys. Chem. Lett., 2, 1161 (2011)

2) C. J. Barile and A. A. Gewirth, J. Electrochem. Soc., 160, A549 (2013)
Electrochemical Deposition and Dissolution Behavior of Magnesium Metal in Organosilicon-Containing Electrolyte Solutions
Authors: Ouchi Masanobu , Fukutsuka Tomokazu , Miyazaki Kohei , Abe Takeshi
Published: February 2020

Introduction:

Magnesium metal rechargeable batteries are expected as post lithium-ion batteries. One of the drawbacks of the development of magnesium metal rechargeable batteries is electrolyte. Research for electrolyte has been investigated extensively. We also reported the magnesium(II) bis(trifluoromethanesulfony)amide (Mg(TFSA)2)/triethylene glycol dimethyl ether (triglyme) that enabled magnesium metal to deposit/dissolve at ambient temperature[1]. However, low coulombic efficiency and large over potential should be overcome. In this study, fluoroorganosilicon compound (FOS) that has high electrochemical and thermal stability was used as co-solvent to overcome these issues. Electrochemical deposition and dissolution behavior of magnesium metal in the Mg(TFSA)2/ triglyme+FOS was investigated.

Experimental:

A three-electrode cell was used. Platinum plate was used as a working electrode and magnesium wires were used as a counter electrode and a quansi-reference electrode. 0.5 mol dm-3 Mg(TFSA)2/triglyme+FOS(various ratio) was used as electrolyte solutions. Cyclic voltammetry and chronopotentiometry measurement was carried out. X-ray diffraction (XRD) measurement and scanning electron microscope (SEM) observation were conducted. All operations and electrochemical measurements were carried out in Ar-filled glove box.

Results and discussion:

Figure 1 shows the cyclic voltammograms of the Pt electrode in Mg(TFSA)2/triglyme and Mg(TFSA)2/triglyme+FOS (1:2 by vol.) at the 5th cycle. Both reduction and oxidation currents were observed at the potential around - 2 V and 1 V, respectively. After chronopotentiometry, magnesium metal deposition was confirmed by XRD pattern and SEM image. Coulombic efficiency in triglyme+FOS was higher than that in triglyme. Based on this result, it is suggested that the addition of FOS is effective to magnesium metal deposition and dissolution reaction in triglyme.

Reference:

1. T. Fukutsuka, K. Asaka, A. Inoo, R. Yasui, K. Miyazaki, T. Abe, K. Nishio and Y. Uchimoto, Chem. Lett., 11 (2014) 1788.

Figure 1
Exploration of Side Reactions Based on Graphite-Li2O2 Redox Couple for Lithium Oxygen Battery
Authors: Zhang Wang , Shen Yue , Huang Yunhui
Published: February 2020

In recent years, lithium oxygen batteries (LOBs) have been considered as one of most promising energy storage systems for long-range electric vehicles and smart grid due to its high energy density.1-3 However, there are many fundamental scientific problems hinder it’s realization from theory to practice, including the sluggish oxygen evolution reaction (OER), the instability of electrode/electrolyte and the contamination of H2O/CO2/N2 in air. The instability of electrode and electrolyte always leads to serious side reactions which result in high charge overpotential and poor cycle life. In the study of LOBs, Li metal is usually used as the anode material to achieve high energy densities because Li is the lightest and most electropositive metal. Besides, the amount of Li metal is always far enough in our battery system. Thus, the electrochemical performance obtained with excess amount of Li metal could not reflect the true performance of our battery due to the existing side reactions which will constantly consume the lithium sources.4

To solve this problem, we used a graphite-Li2O2 redox couple for LOBs. Fig. 1 shows the typical charge-discharge profiles of Li-graphite, Li-O2 and graphite-Li2O2 batteries. Further, we systematically investigated the side reactions occurred in this battery system and evaluated its impact on the cycle performance of LOBs. Graphite has been widely used as anode material in commercial lithium ion battery, and has also been investigated in lithium sulfur and lithium oxygen batteries.4-6 In our cases, we used LISICON protected graphite as anode to avoid the contamination of O2. Lithium peroxide-carbon composites were used as cathode and acted as the only lithium source for LOB. The battery was cycled at different C-rates and the cathode was measured by multiple analysis methods including SEM, TEM, Raman/FTIR, HNMR etc.

Reference

1. Abraham, K. M.; Jiang, Z. J. Electrochem. Soc.
1996, 143, (1), 1-5.

2. Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J.-M. Nat. Mater.
2012, 11, (1), 19-29.

3. Luntz, A. C.; McCloskey, B. D. Chem. Rev.
2014, 114, (23), 11721-50.

4. Chun, J.; Kim, H.; Jo, C.; Lim, E.; Lee, J.; Kim, Y. ChemPlusChem
2015, 80, (2), 349-353.

5. Agostini, M.; Scrosati, B.; Hassoun, J. Adv. Energy Mater.
2015, 5, (16), 1500481.

6. Bhargav, A.; Fu, Y. J. Electrochem. Soc.
2015, 162, (7), A1327-A1333.

Figure 1
Tuning Dopant Chemistry in the Na3PS4 Glass-Ceramic Electrolyte
Authors: Chu Iek-Heng , Zhu Zhuoying , Kompella Christopher , Nguyen Han , Deng Zhi , Hy Sunny , Meng Ying Shirley , Ong Shyue Ping
Published: February 2020

Cubic Na3PS4 (c-Na3PS4) [1] is one of the most promising sodium superionic conductor solid electrolytes that may enable safer and more energy dense rechargeable batteries based on sodium-ion chemistry. Experimentally, Na+ conductivities as high as 0.74 mS cm-1 have been achieved via improvements in synthesis and doping.[2] In this talk, we will present an integrated first principles and experimental study of the effect of dopant chemistry on Na+ conductivity in Na3PS4. Using ab initio molecular dynamics (AIMD) simulations,[3] we show that pristine c-Na3PS4 is in fact an extremely poor Na ionic conductor, and it is only with the introduction of Na+ excess via M4+ for P5+ doping that reasonable conductivities close to the experimentally observed values are achieved. A systematic evaluation of different M4+ dopants find that 6.25% Sn4+ doping may yield an even higher Na+ conductivity, albeit with a slight increase in doping energy. We will also present recent results on alternative doping strategies that yield similarly high conductivities in the tetragonal polymorph (t-Na3PS4), with the potential advantages of a simpler synthesis path and improved SEI composition at the electrode-t-Na3PS4 interface.

References:

[1] Hayashi, A.; Noi, K.; Sakuda, A.; Tatsumisago, M., Nat. Commun, (2012), 3, 856.

[2] Tanibata, N.; Noi, K.; Hayashi, A.; Tatsumisago, M., RSC Adv., (2014), 4, 17120.

[3] Zhu, Z.; Chu, I.-H.; Deng, Z.; Ong, S. P., Chem Mater., (2015), 27, 8318.
Resistive Sensors Based on Self-Assembled Core-Shell Nanoparticles
Authors: Baklouti Linda , Rajoua Khalil , Favier Frederic
Published: February 2020

A gas sensor allows the detection thanks to the specific reactivity of its sensitive material towards the target gas.

The use of resistive sensors is based on measuring the variation of their electrical conductivity when the target gas is in contact with the sensitive material.

In our study, we chose to work with self assembled core-shell nanoparticles as sensing materials. The idea consists on decorating spherical gold nanoparticles, insensitive to the target gases, with a shell based on a different material. The latter provides the specific sensitivity to the sensor.

Previous works in our laboratory focused on Au@Pd and Au@Pt nanoparticles as H2 sensors. These works were extended to other shell materials to examine their sensitivity towards H2 as well as other target gases including NH3.

Au@ZnO, Au@SnO2 and Au@Ag nanoparticles were synthetized and then assembled by Langmuir Blodgett technique. The assembly resulted in close-packed core-shell nanoparticle monolayers. These layers were transferred, by simple dip-coating, to a glass slide supporting interdigitated electrodes. Sensing performances of the as fabricated sensors were evaluated through the resistivity changes in the discontinuous particle assemble.

The sensitivity of Au@ZnO and Au@SnO2 based sensors was tested towards H2 while Au@Ag based sensors were tested under NH3. All sensors showed responses towards the target gases. The effect of humidity and the sensing temperature on the sensing performances were studied. Besides, among the main sensor proprieties requested and studied we note : sensitivity, selectivity, response and recovery times.

Assembles of core-shell nanoparticles organized with Langmuir-Blodgett technique demonstrated attractive sensing performances towards H2 and NH3 in extended concentration ranges.

Another important contribution concerns the elucidation of the sensing mechanisms. Various analytical techniques including Temperature Programmed Desorption, Temperature Programmed Reduction and Microcalorimetry were used to allow the discussion of the sensing performances towards mechanisms.

Figure 1
A Three Electrode Mixed Potential Sensor for Gas Detection and Discrimination
Authors: Tsui Lok-kun , Benavidez Angelica D , Palanisamy Ponnusamy , Evans Lindsey , Garzon Fernando H
Published: February 2020

Mixed potential solid state electrochemical sensors potentially serve as devices for detection of pollutants from industrial and automotive exhaust and can screen dangerous explosive chemicals in security sensitive areas. In these sensors the difference in catalytic activity between two electrode materials produces a voltage from the difference in the mixed potential that is established at steady state. By integrating multiple electrodes on a single substrate, each pair tuned to be sensitive to different gases, a device can be produced which is selectively sensitive to a variety of gases.

The three-electrode sensors were fabricated by ESL ElectroScience with a high temperature co-firing technique on an insulator-YSZ-insulator substrate and Pt, La0.8Sr0.2CrO3 (LSCO), and Au0.5Pd0.5 electrodes were applied by screen printing. A porous YSZ layer over the electrodes serves as the electrolyte, and a length of Pt is printed on the back to serve as an integrated heater. The heating is applied by a control board which imposes a constant resistance, maintaining the temperature during the testing at various flow rates. The sensors were tested at 450-500oC in a 10% O2 atmosphere to different test gases which include NOx, CO, C3H8, (Figure 1) and mixtures of these gases. The Au/Pd+Pt pair is found to be most sensitive to NOx and CO, the LSCO+Pt pair is most sensitive to NOx and C3H8, and the Au/Pd+Pt pair is sensitive only to CO. Against 50-200 ppm backgrounds of NOx and C3H8, the introduction of 100 ppm CO to the gas stream yields a 30 mV response on the Au/Pd+Pt and Au/Pd+LSCO pairs, but produces less than 10 mV shift on the LSCO+Pt pair. Once sets of data consisting of voltage responses to blends of gases were collected, we successfully trained artificial neural networks to associate voltage responses with both binary gas mixture ratios and absolute concentrations of gases, as well as identify which mixtures of gases were present.

Figure 1. Response of the three-electrode sensor at 450oC to different gases, where a preferential selectivity towards CO is seen in Au/Pd+Pt or Au/Pd+LSCO pairs and a selectivity towards C3H8 is seen in LSCO+Pt.

Figure 1
Fabrication of a Room Temperature Electrochemical Gas Sensor Using Paper Substrate
Authors: Sekhar Praveen K. , Kysar Jesse
Published: February 2020

Recent increases in threats to public health, safety, and security have generated a need for more reliable and rapid detection of volatile and toxic gases. To achieve a reliable and versatile gas sensing system capable of being fabricated at the micro-scale a sensor with high selectivity, rapid response time, and low power requirements that is capable of being fabricated easily with low cost at the micro-scale is needed. A promising new approach to detecting gases is by electrochemical sensing using room temperature ionic liquids (RTILs) as the sensing electrolyte. Electrochemical methods of detecting gases provide superior selectivity with low power consumption and have a wide range of gases that can be detected. RTILs are stable conductive ionic compounds which are liquid at room temperature but that also have extremely low vapor pressure, high thermal stability, and wide potential windows. These traits combined with the capability of room temperature operation gives RTIL sensors a distinct edge over traditional heated gas sensing technology. Combining this fundamental sensor structure with electrochemical measurement techniques such as electrochemical impedance spectroscopy (EIS) and amperometry allows for simple and reliable detection of a variety of gases. The hurdle of delayed response of RTIL sensors due to diffusion of the target gas is overcome by ink jet printing the circuitry, electrodes and the RTIL on high temperature resistant, flame resistant paper. The added benefits of using the fabrication method of ink jet printing are reduced cost and in situ fabrication. Printing on paper reduces cost and adds flexibility and durability to open up this versatile sensor to applications such as wearable sensors as an early warning system for areas where hazardous gases can cause serious injury or even death and further incorporation of sensors in transit security, for instance by embedding them in luggage tags.

This research presents a room temperature ionic liquid (RTIL) gas sensors printed with on flexible and low cost heat resistant paper substrate. The electrodes are ink jet printed using both indium tin oxide and gold ink separately to achieve the optimum design for reliability, speed, precision, selectivity, size and cost. The fabrication process for a 1mm x 1mm RTIL gas sensor is presented with the measured responses to methane and ammonia. This flexible, inexpensive, and wearable sensor structure allows for widespread deployment of gas sensing technology in security sensitive or crowded public, government, and transit areas.