bluuebunny/crossref_metadata_2025 huggingface dataset:
Real Time Observation of Electrochemical Deposition Process of Zinc Dendrites Via Correlative Optical and X-Ray Microscopy
Authors: Park Jeung Hun , Raj Abhishek , Gupta Tanya , Steingart Daniel A
Published: February 2020

Low cost, durable, and relatively safe electrode materials are highly desirable for electrochemical energy storage devices, but the implementation of many materials, including zinc, is limited by morphological transformations that take place during electrochemical cycling [1]. The formation of unstable growth morphologies, notably dendrites with highly anisotropic and porous structures is vulnerable to mechanical vibrations and can cause catastrophic failure by shorting the anode and the cathode [2]. The development of improved secondary batteries depends critically on a detailed understanding of the physical and electrochemical processes at the electrode-electrolyte solid-liquid interface [3]. Recent advances in in situ electrochemical microscopy [4], with its unique ability to provide simultaneous temporally and spatially resolved information as well as electrochemical parameters, enable exploration of the underlying physics of electrochemical reactions at the solid-liquid interface [5].

In this work, we investigate electrodeposition process that forms and takes place on the surface and inside of metal electrodes at real time. By employing a microfluidic cell and the capability for liquid flow, we can introduce electrolytes (i.e. 8.9M KOH + 0.61M ZnO or 0.5M H2SO4 + 0.1M ZnSO4) with varying composition of metal ions, pH and chemical additives (i.e. Bi2O3 or PbSO4), and apply different current and voltage parameters to investigate their effects on the deposited morphology. We employ in situ correlative light and transmission X-ray microscopies to track nucleation, growth, and propagation of Zn dendrites. We also discuss the effects of additives to the electrolyte, which can change the onset of dendrite formation during the electrodeposition of Zn. We also compare these microfluidic cell results to liquid cell electron microscopy experiments in which we have recorded Zn morphology after galvanostatic deposition, and we will discuss the benefits and pitfalls of the correlative microscopy technique for the study of processes during battery operation.

 

References:

[1] Y. Li & H. Dai. Chem. Soc. Rev. 43, 5257–5275 (2014).

[2] Z.-L. Wang, D. Xu, J.-J. Xu, & X.-B. Zhang. Chem. Soc. Rev. 43, 7746–7786 (2014).

[3] J. W. Gallaway, D. Desai, A. Gaikwad, C. Corredor, S. Banerjee, & D. Steingart. J. Eectrochem. Soc. 157, A1279–A1286 (2010).

[4] C. P. Grey & J. M. Tarascon. Nat. Mater. 16, 45–56 (2017).

[5] N. Hodnik, G. Dehm, & K. J. J. Mayrhofer. Acc. Chem. Res.
49, 2015–2022 (2016).

[6] We gratefully acknowledge funding supports from the BP Carbon Mitigation Initiative.
How in Situ Analytics Advances Our Understanding of Electrocatalytic Materials and Reaction Processes – a Few Case Studies
Authors: Strasser Peter
Published: February 2020

In this contribution, we share a few recent examples where in situ analytical techniques have advanced our understanding of structure-activity relationships of electrocatalysts and electrocatalytic reactions. Special emphasis will be placed on synchrotron-based X-ray techniques, new approaches in electrochemical mass spectrometry, and in-situ electrochemical transmission electron microscopy. Reactions of interests include the oxygen reduction reaction on Pt based and carbon based catalysts, the oxygen evolution reaction on CoOx and NiFeOx, as well as the electroreduction of CO2.
X-Ray Tomography and Thermography Investigation of a High-Modulus Solid Electrolyte for All Solid-State Batteries
Authors: Seitzman Natalie , Johnston Steve , Platt Heather A.S. , Harvey Steve , Son Seoung-Bum , Zenyuk Iryna V. , Al-Jassim Mowafak , Pylypenko Svitlana
Published: February 2020

All solid-state lithium batteries offer a necessary improvement to the safety of electric vehicles (EVs) in addition to the capacity improvements enabled by the use of lithium metal as an anode material. In order to accelerate the use of lithium metal anodes and solid electrolytes in consumer products, it is vital to understand the cycling behavior, electrode-electrolyte interfaces, and failure mechanisms of such systems. A promising class of solid electrolytes for achieving the use of all solid-state batteries in EVs is lithium-phosphorous-sulfides, which includes β-Li3PS4. This electrolyte has an ionic conductivity on the order of 10-3 S cm-1 and can be compressed to 80% density at room temperature.

This work probes the morphological evolution of the electrode-electrolyte interface and observes the growth of lithium dendrites in β-Li3PS4 using x-ray tomography, guided by thermography. Thermography enables the direct visualization of short circuits in the electrolyte, which are shown in Figure 1 to preferentially form in continuous boundary or void spaces, and identifies locations of interest to examine with x-ray tomography. With the density dependence of x-ray microscopy, it is possible to examine the correlation of lithium dendrite growth to voids or phase defects and to better understand the behavior of dendrites in high-modulus electrolyte systems. In order to better understand the reactions and mechanisms occurring during cycling as a function of current density, morphological changes detected with x-ray tomography are correlated with chemical information acquired using energy dispersive spectroscopy (EDS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Results will be presented for cold-pressed pellets of the conductive ceramic powder enclosed in lithium-lithium symmetric cells compared over three conditions: uncycled cells, cells cycled under low current, and cells cycled under high current, both for a specific amount of charge.

Figure 1
(Invited) Understanding Electrocatalytic Pathways in Complex Organic and Inorganic Composites in Aqueous and Non-Aqueous Environments
Authors: Mukerjee Sanjeev
Published: February 2020

There are very few techniques that lend themselves to rigorous requirements, where the individual role of different transition metal components of nano-phasic materials can be investigated in both amorphous and crystalline forms. We have developed a new analytical technique along with theoretical calculations, which enables the amount and specific adsorption site of species such as H, OH, O, CO, other C1 moieties and even anions such as bisulfate to be determined in situ on a transition metal surfaces using synchrotron XANES data. This technique, commonly called the ‘Delta Mu (∆μ) Technique’ can be taken in situ in both electrochemical cells and operating fuel cells, and can be obtained from a wide variety of transition metal surfaces and alloys, including non-Pt based metal electrocatalysts with element specificity. EXAFS data taken concurrently provide information on the changes in short range atomic order around the absorber atom thereby providing structural information such as bond distances and coordination numbers (thereby information on average cluster size, homogeneity and surface segregation etc.).

In this presentation among other things we will show in-situ XAS study of group of (Metal-Nitrogen-Carbon) MNC catalysts from perspective of metal center. We will demonstrate the presence of ORR active bio-mimetic porphyrin-like FeNx functionalities (Fig.1), as well as other forms of the metal which indicate no catalytic activity. The XAS in-situ studies will be combined with electroanalytical evaluations using cyclic voltammetry (CV) and square wave voltammetry (SWV) as well as in situ Raman spectroscopy. Further the factors governing the ORR activity at MNC centers, such as the Lewis basicity of the carbon support and the accompanying changes in the redox potential of the metal center will be discussed. This presentation will bring together electrochemistry and XAS spectroscopy (including ∆μ) on effect of pH (inner and outer sphere charge transfer) and aqueous vs. non-aqueous electrolyte (concerted vs. non concerted charge transfer).
Elucidating the Pre-Oxygen Evolution Surface Chemistry on Ruthenium Dioxide Surfaces
Authors: Rao Reshma R , Kolb Manuel J , Halck Niels , Pedersen Anders Filsøe , Mehta Apurva , You Hoydoo , Stoerzinger Kelsey A. , Hansen Heine A. , Feng Zhenxing , Zhou Hua , Rossmeisl Jan , Vegge Tejs , Chorkendorff Ib , Stephens Ifan Erfyl Lester , Shao-Horn Yang
Published: February 2020

The unique interaction between water and rutile Ruthenium Dioxide (RuO2) affords high pseudocapacitance and catalytic activities for a number of reactions such as the oxygen evolution reaction (OER)1,2,3. While the low energy, RuO2 (110) and (100) surfaces have been studied as model systems for gas phase catalysis and ultra high vacuum surface science studies4,5, the nature of adsorbed species in aqueous solutions remains to be understood. In this work, we examine the structural and chemical changes occurring on oriented RuO2 single crystal surfaces as a function of potential, in acidic electrolyte, using in situ synchrotron-based surface X-ray diffraction (crystal truncation rod) measurements. We find that the positions of the surface Ru and O atoms are largely unchanged from 0.5 V to 1.5 V versus the reversible hydrogen electrode (RHE) scale while adsorbed water molecules on the co-ordinatively unsaturated site (CUS) are deprotonated gradually with increasing potential. At oxygen evolution potentials, we observe the formation of an –OO like group on the co-ordinatively unsaturated site, which is the probable precursor of the evolved oxygen. In order to validate experimentally observed changes in the nature of adsorbed oxygen, we use density functional theory to compute surface Pourbaix diagrams that show the most stable surface termination at any given potential. The experimental and computational results are in strong agreement and provide an atomistic understanding of the surface structural changes associated with the redox transitions prior to oxygen evolution and its implications on the oxygen evolution pathway on RuO2.

References

[1] Trasatti S. Electrochimica Acta. 1984;29(11):1503-1512.

[2] Lee Y, Suntivich J, May KJ, Perry EE, Shao-Horn Y. The Journal of Physical Chemistry Letters. 2012;3(3):399-404.

[3] Stoerzinger KA, Qiao L, Biegalski MD, Shao-Horn Y. The Journal of Physical Chemistry Letters. 2014;5:1636-1641.

[4] Over H. Chemical Reviews. 2012;112(6):3356-3426.

[5] Sun Q, Reuter K, Scheffler M. Physical Review B. 2003;67(20):205424.
(Invited) On the Balance of Intercalation and Conversion Reactions in Battery Cathodes
Authors: Hannah Daniel C. , Gautam Gopalakrishnan Sai , Canepa Pieremanuele , Ceder Gerbrand
Published: February 2020

Batteries based on the intercalation of multivalent ions, such as magnesium, offer substantial improvements in volumetric energy density owing to non-dendritic plating/stripping on high-energy density metal anodes. However, the stability of magnesium oxide (MgO) creates a strong driving force for reactions between Mg2+ ions and transition metal oxide cathodes to follow a conversion pathway (resulting in MgO and reduced transition metal oxides) rather than the desired intercalated pathway. The formation of MgO is particularly problematic: In addition to destroying intercalation cathode material, Mg2+ conductivity in MgO is low enough that MgO is effectively passivating with regard to further insertion/removal of Mg. Such conversion reactions have been observed in several materials and postulated to occur in many others. However, it is not presently known a priori which materials will follow an intercalation (or conversion) reaction pathway: Some materials predicted to be unstable upon magnesiation nevertheless exhibit reversible intercalation, while other seemingly-stable materials undergo conversion reactions.

Understanding which materials favor intercalation (and why) will guide future cathode discovery efforts and can provide insight about which chemical properties govern the balance between conversion and intercalation, aiding the rational design of new materials. In this presentation, I will discuss our efforts to analyze this balance across chemical and structural space (including extension to sulfides, selenides, and other multivalent working ions) using density functional theory (DFT) calculations. I will also describe the trends and insights that emerge from the resulting data, including the impact of polymorph selection and transition metal chemistry on the driving forces for intercalation/conversion.

Figure 1
(Keynote) In-Situ Synthesis of Compact Li2s@Graphene Nanocapsules for High Performance Li-S Batteries
Authors: Tan Guoqiang , Xu Rui , Xing Zhenyu , Yuan Yifei , Wen Jianguo , Liu Cong , Ma Lu , Wu Tianpin , Lu Jun , Ji Xiulei , Amine Khalil
Published: February 2020

For the practical applications of Li-S batteries, excellent energy/power densities and long cycling lifetimes along with high electrode mass loading must be achieved. This requires rational design of cathode’s architectures to facilitate fast electronic and ionic transport as well as accommodate the electrode’s volumetric change. Here we report a compact Li2S/graphene cathode architectural design, where crystalline Li2S nanoparticles wrapped by graphenes are generated simultaneously by burning lithium foil in CS2 vapor, thus forming Li2S@graphene nanocapsules. This structure represents the high possible volumetric efficiency for accommodating sulfur active species while providing superior electrical properties. As a result, the composite electrode exhibits remarkable electrochemical properties, where at a mass loading of 10 mg cm−2, the electrode delivers high reversible capacity of 1160 mAh g−1
S at 0.1 C rate and 800 mAh g−1
S at 1.0 C rate as well as stable cycle performance.

Figs. 1a,b illustrate the nanocapsule structure of Li2S@graphene. TEM images show that the particles have a compact core-shell shape, where the crystalline Li2S cores display highly ordered lattice fringes, and they are surrounded by a contour coating of ~ 10 to 20 graphene layers, thus forming a capsule-like nanostructure. Figs. 1c-f show the electrochemical performance of Li2S@graphene composite. Even at a high electrode loading of 10 mgLi2S cm−2, the cell delivers a high initial charge capacity of 1600 mAh g−1 and a high discharge capacity of 1160 mAh g−1. The capacity remains at 600 mAh g−1 after 200 cycles. In addition, the cell exhibits a good rate capability with high discharge capacities of 1230 (0.1 C), 1105 (0.2 C), 984 (0.5 C), 802 (1.0 C), and 600 mAh g−1 (2.0 C). This finding is mainly attributed to the improved electrical properties, electrochemical kinetics, and structural stability of Li2S@graphene nanocapsules. In a word, this compact Li2S@graphene capsule nanostructure exhibit good electrochemical performance.

Fig. 1 Structural and electrochemical characterization of Li2S@graphene nanocomposite. (a) TEM images of Li2S@graphene nanocapsules. (b) Schematic showing the compact nanocapsule structure. (c) Voltage profiles and (d) Cycling performance of Li2S@graphene electrode based on electrode loading of 10 mgLi2S cm−2. (e) Voltage profiles at different charge/discharge current densities, and (f) Long rate cycling performance of Li2S@graphene electrode based on electrode loading of 5 mgLi2S cm−2.

Figure 1
(Invited) Lithium Metal Batteries Using 3D Ionic or Electronic Frameworks
Authors: Hu Liangbing
Published: February 2020

I will discuss our recent progress on Li metal batteries using multilayer Garnet structures, including bilayer and trilayer frameworks. Results based on various cathode including S, oxygen and high voltage cathodes will be discussed.

I will also discuss our results on garnet nanostructures including 3D printed garnet framework, garnet paper and garnet fabrics which function as ionic conductive frameworks to enable stable, high current cycling of thick Li metal anode. Flexible garnet nanofiber-polymer hybrid electrodes with a high tortuosity and excellent mechanical strength will also be discussed.

In the end, I will discuss low-tortuosity Li metal anode guided by anisotropic wood-based carbon framework.

References:

Bilayer Garnet Solid Electrolyte Based High Energy Density Lithium Metal-Sulfur Batteries, Energy and environmental Science, Accepted.

High-Capacity, Low-Tortuosity, and Channel-Guided Lithium Metal Anode. PNAS, 2017.

Flexible, Solid-State Lithium Ion-conducting Membrane with 3D Garnet Nanofiber Networks, PNAS, 2016, 113, 26,7094.
Multifunctional Pyridinium Systems for Nonaqueous Redox Flow Batteries
Authors: Guarr Thomas F. , Petty Anthony , Olson Kevin , Mann Shane
Published: February 2020

Viologens are among the most thoroughly studied redox active organic compounds, and many examples display two distinct reversible reductions under appropriate conditions. However, by introducing p-phenylene or p-biphenylene bridges between the pyridinium rings, substantially different electrochemical behavior is observed. Specifically, the stabilization afforded by the quinoidal form of the doubly reduced species can lead to coalescence of the pyridinium reduction peaks into a single, net 2e- wave. We have employed simple and straightforward synthetic routes to various flavors of multi-pyridinium materials. Two, three, and four electron systems have been demonstrated, and more complex systems capable of accepting six or more electrons are currently being developed. These materials are well characterized by NMR, ESI-MS, electrochemical, and spectroelectrochemical methods. Correlations between structure, redox potential, spectroscopic properties, and stability will be described, as will our efforts to develop and optimize such systems for applications in redox flow batteries.
Nested ZnO Nanostructure Gas Sensor with AZO Coating By Atomic Layer Deposition
Authors: Lin Pengtao , Chen Xin , Zhang Kai , Baumgart Helmut
Published: February 2020

ZnO is a well-known Metal Oxide Semiconductor (MOS) material used in gas sensor applications due to its good electrical property, wide band gape of 3.37 eV, ~60 meV exciton binding energy, low cost, and high mechanical stability. Especially, ZnO nanorod structure is widely investigated in gas detection due to its high surface-to-volume ratio, nontoxicity, and suitable doping. Numerous methods have been applied to enhance the sensing performance of ZnO nanostructure gas sensors. In this research, a coaxial nanorod/nanotube structure was fabricated to improve the sensing response of ZnO nanorods to ethanol vapor, as shown in Figure 1. Also, due to additional oxygen vacancies, Al doped ZnO (AZO) thin films were deposited on the surface of ZnO nanorod/nanotube to further enhance the sensitivity of ZnO nanorods.

In this study, the ZnO seed layers were deposited on Si wafer by Atomic Layer Deposition (ALD) with diethylzinc ((C2H5)2Zn) and DI water as precursors of zinc and oxygen. Physical vapor deposition (PVD) was carried out to synthesize aligned ZnO nanorods shown in Figure 1(a). There was a layer of Al2O3 as sacrificial spacer deposited on the surface of ZnO nanorods by ALD with TMA (Al2(CH3)6) and DI water as precursors shown in Figure 1(b). An additional layer of ZnO thin film was synthesized by ALD shown in Figure 1(c) and Figure 2(a). To expose the Al2O3 sacrificial spacer layer, Precision Ion Polishing System (PIPS) was introduced to remove the top cover of synthesized ZnO nanorods shown in Figure 1(d) and Figure 2(b). Then Sodium hydroxide (NaOH) was applied to remove the Al2O3 layer to form ZnO nanorod/nanotube structure as shown in Figure 1(e) and Figure 2(c). As shown in Figure 1(f) and Figure 2(d), AZO thin films were deposited on the surface of ZnO nanorod/nanotube by ALD to further enhance its sensing performance to ethanol vapor. Field emission scanning electron microscopy (FE-SEM) to investigate the morphology of ZnO nanorod/nanotube before and after coated with AZO thin films by ALD. The crystal structures of ZnO nanorod/nanotube before and after coated with AZO thin films were analyzed by X-ray diffraction (XRD).

To investigate the sensing performance of ZnO nanorod/nanotube to ethanol vapor, a gas sensor testing system was designed and built with a sealed reaction chamber, ethanol vapor generator, testing circuit, and controlled heating system. The physical change of ZnO nanorods to ethanol vapor is resistance. Therefore, the resistance of ZnO nanorod/nanotube was recorded by the home-built sensor testing system based on Labview and CompactRio system from National Instruments. ZnO nanorod/nanotube samples before and after coated with AZO thin films were tested under various volumes of ethanol vapor at different temperatures to analyze their sensing responses. A sensing response comparison was made between ZnO nanorods and ZnO nanorod/nanotube.

Figure 1
Fabrication of Hierarchical Nanostructures for Surface-Enhanced Raman Scattering Biosensors
Authors: Curtin Kathrine , Kasani Sujan , Zheng Peng , Wu Nianqiang
Published: February 2020

Biosensors are novel devices for offering fast, point of care results in healthcare fields. Nanostructures can improve the performance of biosensors. For example, plasmonic gold nanohole arrays have been demonstrated to amplify the surface-enhanced Raman scattering (SERS) signal in biosensors because of their unique optical properties and highly tunable localized surface plasmon resonance (LSPR). However, it remains a challenge to fabricate nanostructures such as nanohole arrays. Herein a gold nanohole array-silica spacer-gold nanodisk array has been fabricated based on nanosphere lithography. The SERS effect is considerably improved due to the plasmonic coupling between the gold nanohole array and the nanodisk array separated by a small silica gap (~10 nm). Ultraviolet-visible spectroscopy, Raman spectroscopy, and finite-difference time domain simulations have been used to characterize the performance. The plasmonic nanostructure obtained can be potentially integrated into microfluidic devices for healthcare and environmental monitoring.
New Class of Non-Corrosive, Non-Nucleophilic and Highly Efficient Electrolytes for Rechargeable Magnesium Batteries
Authors: Fichtner Maximilian , Zhao-Karger Zhirong
Published: February 2020

It will be shown that fluorinated alkoxyborates based magnesium electrolytes are weakly coordinated systems, which exhibit a high anodic stability (4.3 V vs. Mg), high ionic conductivity (7 mS/cm) and high Coulombic efficiency (>99%) of reversible magnesium deposition. Owing to the non-corrosive, chemically stable nature and the robust, economic synthesis in one step from commercially available materials, this design concept of new, weakly coordinated ion conducting salts opens a promising avenue towards the realization of high-energy magnesium batteries.

Synthesis, chemical and structural analysis and electrochemical properties will be presented, as well as its application to Mg-S batteries, where it shows superior performance.
Speciation and Electrochemical Properties of Electrolytes for Mg-Ion Batteries
Authors: Merrill Laura C. , Schaefer Jennifer L.
Published: February 2020

Rechargeable magnesium-ion batteries are under investigation as a possible alternative platform to lithium-ion. Magnesium metal serves as a viable anode for post lithium-ion batteries due to its high volumetric charge capacity and widespread abundance. The electrolyte is identified as a limiting factor in magnesium batteries, as many analogous electrolytes to lithium-ion batteries can passivate the magnesium metal surface preventing rechargeability. Both electrolyte salt(s) and solvent(s) must be chosen to ensure chemical compatibility while facilitating desired electrochemical activity. Here we report our recent efforts to understand the effects of speciation and electrochemical performance of magnesium bis(disilizane)-based liquid electrolytes. We find that the solvent and anion types both effect electrolyte equilibration and complexation, resulting in varying conditioning procedures required, the reversibility and facileness of magnesium deposition and stripping, and oxidative stability.
Lithium Doped High-Performance Intercalation Cathode Materials for Sodium Ion Batteries
Authors: Yang Lufeng , Li Xiang , Ma Xuetian , Xiong Shan , Hu Yan-Yan , Liu Meilin , Chen Hailong
Published: February 2020

High capacity, low cost and long cycle life cathode materials are very much desired to develop high performance sodium-ion batteries (SIBs), which are considered as a possible solution for grid level electrochemical energy storage. Sodium manganese oxides with different compositions and crystal structures are a class of intercalation cathode materials that have high promise because of their high initial capacity and low cost, owing to the use of earth abundant metal, Mn. However, many sodium manganese oxides compounds suffer from fast capacity decay primarily attributed to the irreversible phase transitions in the electrochemical cycling processes. In this work, we report our investigation on a group of Mn-based cathodes with using an effective strategy of mitigating and delaying the phase transitions by compositional design. We report the design, synthesis, electrochemical testing and cycling mechanism study on the compounds with a general formula of Nax(LiyMn1-y)O2 with using lithium as the doping element. Many of this group of materials demonstrated very high initial capacity of >200 mAh/g and good capacity retentions. In-operando X-ray diffraction (XRD), Rietveld refinement and 7Li solid state NMR characterizations are conducted to elucidate the cycling mechanisms of the materials. The stability of the Li-doped structure, the effects of lithium doping and the fate of lithium in extended cycling are also discussed.

Figure 1. The voltage profiles (a) and in operando XRD patterns (b) of the lithium doped sodium manganese oxide cathode.

Figure 1
Freestanding, Binder-Free Metal Sulfide Nanotubes Array As High Efficient Cathode for High Performance Lithium-O2 Batteries
Authors: Wang Jin , Fu Yue , Yu Hai-Yang , Zhang Chenjie , Yao Jianlin , Li Jian-Feng , Li Xiaowei , Tian Jing-Hua , Yang Ruizhi
Published: February 2020

Lithium-O2 battery as a novel energy conversion and storage device has attracted increasing attention [1]. However, it’s still facing great challenges for practical applications, including of large over potentials, poor cycling life [2]. Many reports have shown that a suitable cathode catalyst may could solve these problems [3]. Herein, metal sulfide (NiCo2S4) nanotube arrays on carbon paper were synthesized through a two-step hydrothermal method and then applied as a freestanding, binder-free cathode for lithium-O2 batteries directly. This novel air electrode could deliver a high initial discharge capacity of 12348.5 mAh g-1 with coulomb efficiency of 88.9% (Fig. 1a). Specifically, the discharge/charge over-potentials gap has been reduced to 0.73V, which is much lower than that of the counterpart metal oxide catalyst (NiCo2O4 NWs, 1.24 V)(Fig. 1b). Furthermore, this NiCo2S4 NTs@CFPs air electrode shows excellent long cycling life (485 cycles). This novel air electrode also exhibited great stability and reversibility. Interestingly, the discharge product of the air electrode with NiCo2S4 NTs is film-like amorphous Li2O2, which owns higher charge-transport properties and could be decomposed at a much lower potential than the common crystalline Li2O2. The excellent cell performances could be ascribed to the intrinsic properties of NiCo2S4, including high electrical conductivity and redox activity, the special hollow nanotubes structure, which could provide larger specific surface area and more active sites as well as enough space to accommodate the discharge products. The numerous pores distributed on the nanotube wall could also facilitate the transport of oxygen and electrolyte during the cell operation. This novel freestanding, binder-free air electrode sheds light on the application of metal sulfides not only on Lithium-air batteries, but also other metal-air batteries and fuel cells.

This work was supported by National Natural Science Foundation of China (21673153, 21303114，51272167 and 51572181 ), National Key Research and Development Program of China (2016YFB0100200), Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (15KJB480001) and Natural Science Foundation of Jiangsu Province, China (BK20161207).

 

References:

 1. Bruce P.G., Freunberger S.A., Hardwick L.J., Tarascon J.M. (2012). Li-O2 and Li-S batteries with high energy storage. Nat. Mater., 11, 19-29.

2. Li F.J., Zhang T., Zhou H.S. (2013). Challenges of non-aqueous Li-O2 batteries: electrolytes, catalysts, and anodes. Energy Environ. Sci., 6, 1125-1141.

3. Shao Y.Y., Park S., Xiao J., Zhang J.-G., Wang Y., Liu J. (2012). Electrocatalysts for nonaqueous lithium-air batteries: status, challenges, and perspective. ACS Catal., 2, 844-857.

Figure 1
A Robust Glass Fiber Based Free Standing Composite Electrode for Lithium-Polysulfide Batteries
Authors: Ragupathy P , Abdul Ahad Syed , Lee Hyun-Wook , Kim Do Kyung
Published: February 2020

Lithium-sulfur batteries are attractive energy storage devices for the next generation of rechargeable storage technology in the sector of electric mobility and renewable energy systems. However, the poor electronic conductivity of sulfur, low active materials utilization, dissolution of polysulfide and limited sulfur loading hinders its commercial implementation for practical applications. Herein, we report a flexible glass fiber based free standing electrode (FSE) in lithium-polysulfide batteries with high energy density and long cycle life. The specially designed electrode provides enough space to accommodate large amount of sulfur and facilitate the enhanced immobilization of polysulfide ions. Moreover, MnO2 inbuilt in the electrode favors in suppressing the polysulfide shuttling effect. The initial specific capacity of Li-polysufide (Li2S8) in FSE is 1275 mAhg-1 at 0.2 C with remarkable capacity retention upon cycling. A complete physico-chemical characterization and the electrochemical behavior of free standing electrode will be discussed in detail.
Chemical Formation of Self-Healing Solid Electrolyte Layers on Lithium Anode
Authors: Lim Hee-Dae , Lee Byeongsun , Xing Xing , Liu Ping
Published: February 2020

All solid state batteries have potential to solve safety issues over the current state of lithium ion batteries (LIBs) due to the absence of flammable organic electrolytes [1,2]. Among many components of them, solid electrolyte layer is considered as a key factor enabling all solid chemistries, which can enable high energy density and stable post LIBs. Further, the mechanical strength of solid electrolyte can suppress lithium dendrite growth during cycling and its stable interface can prevent the continuous side reactions caused by organic electrolytes. Finally, solid electrolyte can be a promising solution for the prevailing shuttle problem of post Li-S batteries [3].

Solid electrolytes have so far failed to achieve its great promise and the practical use of all solid batteries have been restricted due to their poor stability and complex synthesis process. Indeed, it has been observed that the penetration of dendrite through the electrolyte layer of mm level thickness lead to a cell failure. Furthermore, fabrication methods for solid electrolyte developed so far are expensive and complex, which commonly requires repeated high temperature heat treatments and compression under high pressure. These limitations are major huddles for current solid electrolyte and all-solid batteries.

Here, we propose a new approach to develop a self-forming and -healing solid electrolyte that can be fabricated by solution processing. We target to form the LPS (Li2S-P2S5) electrolyte layer directly on lithium through the in-situ formation of the solid electrolyte layer, which can eliminate both the complex synthesis process used for the conventional sold electrolytes and the need for high temperature sintering process. Furthermore, by the addition of an oxidant in the solution layer, lithium dendrite growth, even if it ever penetrates the LPS layer, can be prevented, serving as a self-healing mechanism. This design can greatly simplify cell fabrication process of solid electrolyte and the inherent self-healing capabilities can offer a new path for post Li batteries with performance advantage over LIBs.

[1] P. G. Bruce et al., Nat. Mater. 2012, 11, 19-29.

[2] X. Ji et al., Nat. Mater. 2009, 8, 500-506.

[3] Z. Lin et al., J. Maters. Chem. A 2015, 3, 936-958.
Behavior of Manganese-Rich Layered Sodium Oxides in Aqueous Electrolytes
Authors: Boyd Shelby , Augustyn Veronica
Published: February 2020

Aqueous sodium-ion batteries operating in neutral pH electrolytes offer the potential for low cost, low toxicity, high safety, and high power density energy storage for large-scale applications, such as those needed to store electricity from renewable energy sources. However, the mechanisms of ion intercalation into solid-state electrodes operating in neutral pH aqueous electrolytes are not well understood. Layered, Mn-rich sodium oxides are promising electrode materials because of the abundance and safety of manganese. Initial studies of the moisture-stable, layered P2-type oxide, NaxNi0.22Mn0.66Co0.11O2 (NaNMC) show an irreversible phase transition to a hydrated birnessite-like structure during electrochemical cycling in aqueous electrolytes with approximately 25 mAh/g reversible capacity. This work investigates the transformation mechanism of the NaNMC through ex situ X-ray diffraction, in situ Raman spectroscopy, and ex situ transmission electron microscopy. A systematic investigation is then conducted on the effect of transition metal doping in NaNMC to reduce the amount of Ni and Co, and to tune the redox potential and capacity for electrochemical cycling in aqueous electrolytes. In addition, aqueous solutions with both high and low salt concentrations are investigated to determine the effect of the electrolyte on the electrochemical behavior of layered sodium oxides
Ionic Liquid Electrolyte for Enhancing Electrochemical Performance of Antimony Sulfide/Graphene Nanosheets Composite Anode in Sodium-Ion Batteries
Authors: Yang Cheng-Hsien , Li Cheng-Yang , Chang Jeng-Kuei
Published: February 2020

High-capacity carbon-coated Sb2S3/graphene composite anode for sodium rechargeable batteries is synthesized using a facile solvothermal method. An effective additive, 5 vol% fluoroethylene carbonate (FEC), is incorporated into the conventional organic electrolyte to improve the electrochemical performance of the Sb2S3/graphene composite anode due to the formation of more stable solid/electrolyte interface. In 1 M NaClO4 propylene carbonate/fluoroethylene carbonate (PC/FEC, v/v =95:5), maximum capacity of 621 mAh/g and cyclic stability of 43% after 50 cycles are obtained. In contrast, the cells with 1 M NaFSI in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PMP–FSI) ionic liquid shows the comparable capacity of 588 mAh/g and the best cyclic stability of 55% among the studied electrolytes at room temperature. With the increase in cell temperature from 25 to 60 °C, both the maximum capacity and cyclic stability of the cell with PMP–FSI improve significantly because of its high thermal stability (without decomposition below 400 °C) and the reduction of electrolyte and charge transfer resistance. The cell with IL electrolyte delivers the maximum capacity of 734 mAh/g and the cyclic stability of 62%, remarkably higher than those with conventional organic electrolytes at 25 °C and 60 °C. The promising ionic liquid electrolyte for the Sb2S3 anode of sodium rechargeable batteries is thus proposed.
Carbon-Free Hierarchical CoSx Hollow Nanostructure As Anode for Lithium- and Sodium-Ion Batteries
Authors: Hwang Jang-Yeon , Sun Yang-Kook , Myung Seung-Taek
Published: February 2020

The global energy shortage has led to an increased demand for advanced energy storage devices to harness green energy in an efficient manner. Lithium-ion batteries (LIBs) have become a promising choice due to their outstanding features including their high energy density, high power density, and long lifespan. Cobalt sulfides have attracted tremendous attention as promising anodes for lithium-and sodium-ion batteries. However, the delivery of a high capacity with good cycle life conferred by carbon-free cobalt sulfides is a still challenge. In this work, carbon-free CoSx hollow nanospheres have been prepared and investigated as an advanced anode material for both lithium- and sodium-ion batteries. The resultant material features a unique nano-architecture with hollow core and porous shell. Based on time-dependent experiments, an Ostwald ripening process is proposed to describe the formation of the hierarchical hollow structure. By virtue of its appealing structure and conversion electrochemical reaction mechanism, remarkable electrochemical performances (e.g., high Li/Na-storage capacity, excellent cycling stability, and good rate capability) are achieved when this material is utilized as the anode materials in rechargeable batteries. For instance, a high Li/Na storage capacity (1012.1 mAh g−1 and 572.0 mAh g−1) can be delivered after 100 cycles at 500 mA g−1, corresponding to satisfied capacity retentions, suggesting the great promise of this material for application in rechargeable batteries.
Sulphate-Based Cathode Materials for Potassium-Ion Battery
Authors: Masese Titus , Sano Hikaru , Senoh Hiroshi , Shikano Masahiro
Published: February 2020

The dominance of the lithium-ion battery in energy storage systems has been met with concerns over dwindling lithium resources and rising cost. A pragmatic alternative can be found in potassium-ion batteries owing to the abundance, lower cost and sustainable production and use of potassium-based cathode materials for largescale energy applications. Therefore, similar to the lithium chemistry, various potassium-based oxides (e.g., K
x
CoO2 [1], K0.7Fe0.5Mn0.5O2 [2] and K0.27MnO2 [3]) have recently been reported. Parallel to the oxides, a number of polyanion insertion cathode materials have been discovered with credible electrochemical performance (e.g., K3V2(PO4)3[4]). However, unlike the oxides, these polyanionic cathodes inherently suffer from lower theoretical capacity stemming from their high molecular weight, thus decreasing the net energy density. Whilst their capacity is moderate, polyanionic systems offer rich mineral and structural diversity to design potassium-based materials with tunable redox potentials.

In this work, we explored the vast materials database of sulphate-based insertion materials for potassium-ion batteries. Apart from containing economic and Earth-abundant elements, sulphate-based minerals can, in principle, exhibit high theoretical capacities owing to their low molecular weight. In our exploration of the sulphate chemistry for potassium-ion batteries, we are able to take advantage of an extensive database of known minerals, particularly the bimetallic and hydrated sulphate derivatives such as karpovite, alunite, fedotovite K2Cu3O(SO4)2, langbeinite (K2M2(SO4)3; M=Fe, Mn, Cu, Co, Ni), picromerite, mereiterite, etc. One such mineral is goldichite, with the general chemical formula K2M(SO4)2・nH2O. Noting that its structure contained possible K-ion diffusion channels, we attempted to design a yavapaiite insertion compound for potassium batteries. We will highlight the syntheses and electrochemical performance in K-ion cells of such sulphate-based minerals.

 

Reference
s
:

[1] Y. Hironaka, K. Kubota and S. Komaba, Chem. Commun., 53 (2017) 3693.

[2] X. Wang, X. Xu, C. Niu, J. Meng, M. Huang, X. Liu, Z. Liu and L. Mai, Nano Lett., 17 (2017) 544-550.

[3] C. Vaalma, G. A. Giffin, D. Buchholz and S. Passerini, J. Electrochem. Soc., 163 (2016) A1295-A1299.

[4] J. Han, G. –N. Li, F. Liu, M. Wang, Y. Zhang, L. Hu, C. Dai and M. Xu, Chem. Commun., 53 (2017) 1805-1808.

Figure 1
Suppression of O3/P3 Phase Transition for Nanosize NaCrO2 with Enriched Domain Boundaries in Individual Particle
Authors: Tsuchiya Yuka , Glushenkov Alexey , Yabuuchi Naoaki
Published: February 2020

Rechargeable Na batteries are promising to realize sustainable energy development in the future because of the material abundance, and many electrode materials have been actively researched in the world. O3-type NaCrO2
1, 2 is known to show excellent cycle performance and thermal stability3. Additionally, O3 NaCrO2 shows second highest operating voltage among O3-type layered oxides, next to O3 NaFeO2. O3-type layered oxides translate into P3-type layered structure after removing Na from the layered structure. Such phase transitions result in large volume changes associated with increase in interlayer distance because of large repulsive interaction between MeO2 layers. The deterioration of cyclability associated with O3/P3 transitions is, therefore, anticipated as electrode materials.

In this study, nanosize NaCrO2 with enriched domain boundaries in individual particle was synthesized from nanosize cation-disordered rocksalt-type NaCrO2 prepared by mechanical milling. The sample delivers large reversible capacity without voltage plateaus associated with phase transitions as shown in Figure 1a. Ex-situ XRD data clearly indicates that the O3/P3 phase transition is effectively suppressed on charge/discharge processes. High-resolution TEM imaging shows that micrometer-size secondary particles consist of highly crystalline nanosize NaCrO2 particles. These nanosize domains are randomly aligned in the individual particle. We propose that randomly aligned particles with many grain boundaries cancel and suppress gliding of transition metal layers. Moreover, nanosize NaCrO2 shows better capacity retention in Na cells (Figure 1b) on the long-term cycle test.

From these results, we will further discuss the factors affecting phase transitions for O3-type layered structure as positive electrode materials of rechargeable Na batteries for more details.

Acknowledgements

This study was in part granted by MEXT program “Elements Strategy Initiative to Form Core Research Center”, MEXT; Ministry of Education Culture, Sports, Science and Technology, Japan. High-resolution TEM work was carried out with the support from Deakin Advanced Characterization Facility. A.M.G. acknowledges the funding support from Australian Research Council Discovery grant DP160101178.

References

[1] J. J. Braconnier, C. Delmas, and P. Hagenmuller, Materials Research Bullentin,
17, 993 (1982).

[2] S. Komaba et al., Electrochemistry Communications,
12, 355 (2010).

[3] X. Xia, J. R. Dahn, Electrochem. Solid-State Lett.,
15 , A1 (2011).

[4] N Yabuuchi, K Kubota, M Dahbi, S Komaba, Chemical Reviews, 114, 11636 (2014).

Figure 1
Low Cost FeCo Bimetal Cathode for Li-Air Batteries
Authors: Kim Hun , Sun Yang-Kook
Published: February 2020

In spite of the extremely high theoretical specific capacity of lithium oxygen (Li-O2) electrochemistry,1 low energy efficiency makes this system impractical. Among the catalysts, noble metals and their derivatives have shown improved results with low overpotentials during an oxygen evolution reaction (OER).2 Moreover, bimetal noble metal alloys have also exhibited remarkable decreases of charge overpotentials.3 However, use of noble metal based catalysts makes overcoming their inherent high cost impossible. Therefore, low cost catalysts with acceptable performance are essential for practical Li-O2 battery use. In this report, an iron cobalt bimetal-carbon nanotube (FeCo-CNT) composite was synthesized as a catalytic air cathode material for Li-O2 batteries. An Li-O2 battery using FeCo-CNT air electrodes exhibited higher efficiency than that of pristine CNT as well as higher capacity. Spectroscopic and electron microscope analyses showed that the improved cell performances can be attributed to the catalytic effect of FeCo. As a cost-effective non-noble metal catalyst, FeCo-CNT demonstrated performance comparable to noble metal catalysts in Li-O2 systems.

 

References

1. H. G. Jung, J. Hassoun, J. B. Park, Y. K. Sun, B. Scrosati, Nature Chemistry
2012, 4, 579.

2. E. Yilmaz, C. Yogi, K. Yamanaka, T. Ohta and H. R. Byon, Nano Lett., 2013, 13, 4679–4684.

3. B. G. Kim, H. J. Kim, S. Back, K. W. Nam, Y. Jung, Y. K. Han and J. W. Choi, Sci. Rep., 2014, 4, 4225.
A New Conceptual Cathode and Separator Design Enabling High Energy Density Lithium-Sulfur Batteries
Authors: Kang Jin Kyeong , Yang Guijun , Kang Ji Hoon , Park Jong Won , Jung Yongju
Published: February 2020

Significant improvement of lithium ion batteries (LIBs) performances has been achieved with a rapid advance of portable electronic devices over the past quarter century. With a growing demand for high performance power sources, world-wide efforts have been devoted to the development of an alternative battery system to replace current LIBs which face performance limitation in terms of capacity and energy density. Recently, lithium-sulfur (Li-S) batteries have received an unprecedented attention owing to their great potentials such as a large theoretical capacity of sulfur, low toxicity and low cost. As cutting-edge nanotechnologies (e.g., C-S composite concept, mesoporous interlayer) have been employed to Li-S batteries, their performances have been dramatically improved for the past two decades. Despite such remarkable progress, there have remained many issues (i.e., limited cycling performance and low rate properties) which should be addressed for successful commercialization of Li-S batteries. In addition, most approaches to solve those problems need so complex and expensive processes which are so hard to implement them to practical mass production.

Herein, we report a facile and cost-effective approach for the development of high-performance Li-S batteries. Through combining a functional separator to a high-sulfur-loading cathode, which can mitigate the active material loss and confine polysulfide ions within a specific space ensuring a long cycle life, high-performance Li-S batteries are fabricated and their characteristic features are intensively investigated.
Rechargeable Aluminum–Air Battery Using Various Air-Cathode Materials and Suppression of Byproduct Formation on Both Anode and Air Cathode
Authors: Mori Ryohei
Published: February 2020

A problem with the practial realization of the aluminum air battery is that byproducts such as Al(OH)3 or Al2O3 accumulate on the electrodes during electrochemical reaction. The goal of this study is to develop a practical, high-capacity rechargeable aluminum–air battery that resists degradation. We attempted to use different types of active materials for the air-cathode material and used a mixture of AlCl3 and 1-ethyl-3-methylimidazolium chloride as an ionic-liquid-based electrolyte. The air-cathode materials were activated carbon, carbon alloy, ceramic perovskite oxide, aluminum terephthalate as metal–organic framework (MOF), as well as non-oxide ceramic materials such as TiN, TiC, and TiB2. When we used carbon alloy as the air-cathode material, it initially exhibited an electrical current greater than those of the other air cathode materials because of its high catalytic activity in oxygen reduction, although its effect decreased as the charge–discharge reaction proceeded. Ceramic perovskite oxide (LSCF : La0.6Sr0.4Co0.2Fe0.8O3), TiN, and TiC demonstrated stable performance in electrochemical reactions over the long term. In contrast to aqueous-electrolyte-based aluminum–air battery system, our aluminum–air battery did not show typical byproducts on the aluminum anode side after the electrochemical reaction, such as Al(OH)3 or Al2O3, although we observed them on the air cathode side. However, byproduct formation was suppressed when TiN and TiC were used as air-cathode materials. To our knowledge, this is the first report of suppressed formation of such byproducts on both anode and air cathode in an aluminum–air battery. Our results suggest that byproducts accumulate on the air cathode via reaction of aluminum carbonate, which is suppressed with the TiC air cathode.

Figure 1