bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Water Molecules on the Electrochemical Properties of α-MnO2 Hydrate: A Combined Computational and Experimental Study
Authors: Duan Huan , Jiang Baozheng , Li Jia , Xu Chengjun , Gan Lin , Du Hongda 
Published: February 2020

Hollandite α-MnO2 and its hydrate compounds synthesized by wet-chemical routes play a vital role in many aspects of technological applications, especially in energy storage devices. The features of lattice water are very peculiar but poorly understood. We present a combined computational and experimental study on the behavior of water molecules to elucidate many aspects of this problem, including the location and aggregation characteristics and the related electrochemical properties of lithium storage. It is shown that the oxygen atom of water is always located at the tunnel center (2b site) as that site is farther away from the inwall O atoms. Moreover, total energy profiles establish that monomeric water can form four stable configurations with different orientations of the two hydrogen bonds in the tunnel which stabilizes the crystal structure, and transform reciprocally by a kinetically preferred H-O bond rotation at a relatively low activation energy. Observations at high water content reveal that the aggregation between water molecules can further enhance the structural stabilization, showing a nearly linear lattice shrink, improving the electronic properties and facilitating the lithium diffusion in the adjacent tunnels. Remarkably, the hydrated α-MnO2 exhibits a much better high-rate capability during the charge/discharge process. But the early cycling deterioration of charge capacity results from the lithium anchoring and tunnel blocking caused by lattice water, which provides a consistent interpretation of the measured rate performance with cyclic voltammetry, hydroxyl vibrational spectra, and other experiments. Subsequently, lattice water can bring benefits to the electrochemical performance of α-MnO2 electrode, the magnitude of which is controlled by the H2O content, suggesting an easily achievable method for tuning the physical and chemical properties.
(Invited) Transistor Strain Measurement Using Electron Beam Techniques
Authors: Zuo Jian Min , Kim Honggyu , Zhang Jiong , Rouviere Jean-Ruc 
Published: February 2020

Strain and the related stress in nanoelectronic devices play a critical role in semiconductor technologies. In general, strain arises from the lattice mismatch between dissimilar materials and thus strain is critical for the design and growth of epitaxial heterostructures in micro- and nano-electronics. In transistors, strained silicon channels provide a major boost to the performance of metal-oxide-semiconductor field-effect transistors (MOSFETs), e.g., the use of epitaxial strain of Si and Ge alloys in PMOS [1]. In the near term, the transistor technology is pushing towards the sub 10 nm technology node. At this length scale, resolving strain in the devices requires a resolution of sub nanometer with not only high resolution, also high accuracy and reliability. The use of novel architectures and alternative materials in the transistor technology also demands metrology capable of handling these structural and material changes.
High resolution strain measurement can be performed using high energy electrons either in reciprocal space using convergent beam electron diffraction (CBED), scanning electron nanodiffraction (SEND), nanobeam electron diffraction (NBED) [2], or scanning precession electron diffraction (SPED) or in real space through direct imaging using high resolution electron microscopy (HREM), scanning transmission electron microscopy (STEM) [3] or dark-field electron holography (DFEH)[4]. The resolution and strain measurement sensitivities range from Å to several nm and 10-3 to 10-4respectively. Recent developments in aberration corrected STEM especially have improved the spatial resolution to sub- Å and the precision of measuring atomic column positions to picometers [3].
This talk will review high resolution and high sensitivity electron beam techniques for strain characterization in nanodevices and device materials. Examples include planar and a finfet transistors and III-V heterostructures. For finfet transistors, we demonstrate that NBED provides an effective approach for strain mapping (See figure below) and some of challenges will also be highlighted. In III-V heterostructures, we will describe atomic resolution Z-contrast imaging based methods for high resolution interfacial strain analysis and its applications for the investigation of interfacial intermixing and atomic layer-by-layer strain profiles in InAs/GaSb and InAs/InAsSb superlattices, targeted for middle- and long-wavelength IR detection.
References
[1] J. Welser, J. Hoyt and J. Gibbons, Electron Device Letters, IEEE 15 (3), 100-102 (1994)
[2] Beche, A., et al., Ultramicroscopy,131, 10-23 ( 2013).
[3] J.-M. Zuo, A. B. Shah, H. Kim, Y. Meng, W. Gao and J.-L. Rouviére, Ultramicroscopy 136, 50-60 (2014).
[4] Cooper, D., et al., Applied Physics Letters, 96(11), 113508 (2010).
[5] This work is supported by U.S. Army Research Office (Grant No. Army W911NF-10-1-0524 and monitored by Dr. William Clark) through the MURI program, Nanoscience Foundation, France and DOE BES DEFG02-01ER45923.

Figure 1
Numerical Study on Flow Distribution in PEMFC with Metal Foam Bipolar Plate
Authors: Kim Kyoungyoun , Song Myeongho 
Published: February 2020

It is important to uniformly supply the fuel gas into the reaction activity area in polymer electrolyte membrane fuel cell (PEMFC). Recent studies have shown that the cell performance can be significantly improved by employing metal foam gas distributor as compared with the conventional bipolar plate types. The metal foam gas distributor has been reported to be more efficient to fuel transport. In this study, three-dimensional computational fluid dynamics (CFD) simulations have been performed to examine the effects of metal foam flow field design on the fuel supply to the reaction site. Darcy's law is used for the flow in the porous media. By solving additional advection equation for fluid particle trajectory, the gas transport has been visualized and examined for various geometrical configuration of metal foam gas distributor.
†This work was supported by the International Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) (No. 20148520120160)
Effect of Gdl(+MPL) Compression on the PEM Fuel Cell Performance
Authors: Carcadea Elena , Varlam Mihai , Ingham Derek B. , Patularu Laurentiu G , Marinoiu Adriana , Ion-Ebrasu Daniela , Stefanescu Ioan 
Published: February 2020

Two components of the PEM fuel cells play a critical role in obtaining a good performance, namely the gas diffusion layer (GDL) and the micro porous layer (MPL). The target of the reported investigation was the influence of the required gas diffusion layer compression, during stack assembly, onto PEM fuel cell performance. For developing a fuel cell it is necessary to assembly all the components together in order to ensure a good connection and to reduce the leakage problem, and this is done under a compression load. The compression applied can deform the GDL and modify its thickness, porosity, hydrophobicity and electrical resistance, and these can result in damaging or decreasing the performance of the PEM fuel cell. Also, the GDL may intrude in the flow field channels and can lead in significant disturbance of the reactants flow in the channels and consequently to a drop in the performance.
Numerical simulations based on ANSYS software were carried out in order to investigate the effect of the clamping force on the fuel cell performance. Therefore, 4 geometries were considered in our study, by taking into account the uncompressed and compressed GDL and the presence or absence of MPL. Different levels of GDL compression and intrusion were considered and simulated. The 3D multiphase model revealed that the GDL compression and intrusion influence the in-plane gradient in liquid saturation, oxygen concentration, membrane water content, and especially current density profiles. Also, our study showed that inserting a micro porous layer between catalyst layer and GDL can lead to an improvement of the cell performance because it helps ensuring a good water management, reducing liquid saturation.
Influence of Binder Porosity on Gdl Gas Phase Transport
Authors: Eller Jens , Lamibrac Adrien , Marone Federica , Büchi Felix N 
Published: February 2020

In polymer electrolyte fuels (PEFC) carbon fiber based gas diffusion layers (GDL) are used for fine distribution of reactant gases from the flow field channels to the catalyst layer (CL). It is a key component for PEFC as it serves also for water removal from the CL as well as heat and electricity transport between CL and the flow field plates. GDL materials can be classified as woven, felts, papers, where the later type requires a binder to mechanically stabilize the fiber arrangement.
While most GDL binders are solid, the binder of SGL GDLs appears porous and it’s influence on gas phase transport is unclear [1]. In SEM surface images of SGL, GDL binder domains of appear as flake like fine-structure with particles of about 100 to 300 nm (see Fig. 1a). Here, we apply multi-dimensional X-ray imaging techniques and multi-scale numerical simulations to clarify possible contributions of the binder porosity to overall GDL gas transport.
Absorption contrast X-ray tomographic microscopy measurements at the TOMCAT beamline of the Swiss Light Source (SLS) with voxel sizes of minimum 0.16 µm revealed a high porosity (59 %) of SGL 24 BA binder domains of (Fig. 1b). Computational transport simulations on the segmented binder structures showed, that the binder domains provide isotropic effective diffusivity of 0.30. In order to quantify the contribution of the porous binder to the overall fluid transport in the GDL, the obtained binder diffusivity values were used in multi-scale transport simulations of ternary segmented XTM data of representative GDL samples with 2.2 µm voxel size. If the binder was treated as solid, through-plane effective diffusivity of the GDL of 0.1 was obtained. If we applied a multi-scale simulation approach, that treats the binder domain as porous and uses the transport parameters of the binder domain as input values for the coarse scale simulations of the whole GDL domain, the through-plane effective diffusivity increased to 0.4 (+300 %). These numbers will be verified by X-ray ptychograptic computed tomography measurements of the binder fine structure at the cSAXS beamline of the SLS that proved resolutions of up to 16 nm [2].
References
[1]Rashapov, A; Gostick, J.T., In-Plane Effective Diffusivity in PEMFC Gas Diffusion Layers, Transport in Porous Media, 2016, In press.
[2]Holler, M.; Diaz, A.; Guizar-Sicairos, M.; Karvinen, P.; Färm, E.; Härkönen, E.; Ritala,M.; Menzel, A.; Raabe, J. & Bunk, O., X-ray ptychographic computed tomography at 16 nm isotropic 3D-resolution, Sci. Rep., 2014, 4, 3857.
Figure 1: SGL 24 binder fine structure a) SEM image and b) X-ray tomographic microscopy with 0.16 µm voxel size.

Figure 1
Electrical Conductivity Behavior of Impregnated Lstm on Selectively Ni Removed Ni/YSZ Anode Substrate
Authors: Park DaeSoo , Kim Jung Hyun 
Published: February 2020

Generally, nickel and yttria-stabilized zirconia (YSZ) have been preferred as anode materials for Solid Oxide Fuel Cells (SOFCs), because the Ni-YSZ cermet anode shows excellent performance while operating using hydrogen as a fuel. However, Ni-YSZ anodes are known to undergo degradation due to sulfur poisoning, carbon deposition, and mechanical instability when hydrocarbon-containing fuels have been used. One of the strategies to solve these problems is to modify the Ni-YSZ cermet by altering the nickel or YSZ, adding oxide material catalysts, and carrying out surface treatment.
In this study, electrical conductivity behavior of impregnated La0.4Sr0.6Ti0.8Mn0.2O3±δ(LSTM) on selectively Ni removed Ni/8YSZ anode substrate have been investigated when hydrocarbon fuels are being used for SOFC applications. Abrupt weight losses were measured when reduced Ni/YSZ substrates were exposed to HNO3 at the initial stage reaching 5 minutes, indicating that within these first 5 minutes Ni metals on the surface of Ni/YSZ substrates were removed. After 5 minutes, Ni metals were removed with relatively lower removal rate (2.3 x10-3wt%/min) than first 5 minutes. At values below than 3 wt % of impregnated LSTM on Ni removed substrate, electrical conductivity increase and at values greater than 3 wt %, electrical conductivity decreases as it is related to the effective percolation of electrically conducting phase caused by LSTM present on Ni removed Ni/8YSZ anode substrate. Significantly, the electrical conductivity values with 3 wt % of impregnated LSTM on Ni removed substrate were 2.04 x103 and 1.88 x103 S/cm at 700 and 800oC under H2 condition.
Thermoplastic Polyurethane (TPU) Based All-Solid-State Lithium-Ion Batteries
Authors: Liu Yadong , Aliahmad Nojan , Xie Jian , Agarwal Mangilal 
Published: February 2020

The rapidly growing flexible/wearable electronic market drives the research and development of flexible power source systems, especially lithium-ion batteries with high specific energy/power, long cycle life and high safety1. Conventional lithium-ion batteries with fixed shapes and liquid electrolyte are not suitable for flexible applications as they can electrically short and/or cause fire when bended or stretched. However, the use of solid-state electrolytes can replace the liquid electrolytes, thereby leading to all-solid-state batteries that can eliminate the safety issues caused by traditional, flammable liquid electrolytes. Typical solid-state electrolytes for Li-based batteries fall into two categories:(1) inorganic glass/ceramic/crystalline electrolytes and (2) polymer electrolytes. Inorganic electrolytes including some oxides, sulfides, NASICON-type, perovskite-type, garnet-type materials, etc. have promising conductivity2. However, these inorganic electrolytes are typically fragile and not bendable, and therefore cannot be used for flexible electronic devices. In contrast, polymer electrolytes such as polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), Poly(methyl methacrylate) (PMMA), thermoplastic polyurethane (TPU), etc. are elastic and represent good candidates for electrolytes in flexible batteries.
In this work, TPU/Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) was selected as the polymer electrolyte. The conductivity and electrochemical window of this electrolyte are shown in Fig. 1. The 10 mS/m conductivity of the TPU/LiTFSI should be adequate for low-power-consumption flexible electronic devices. The 0~6.2 V electrochemical window is beneficial for most cathode materials for lithium-ion batteries. A LiNi1/3Co1/3Mn1/3O2 (NCM, 4.0 V vs. Li/Li+, specific capacity: 278 mAh/g) and a Li4Ti5O12 (LTO, 1.5 V vs. Li/Li+, specific capacity: 175 mAh/g) was used as cathode and anode materials, respectively, for the all-solid-state battery (Fig. 2). The LTO was chosen to be the anode because the TPU is sensitive to lithium metal, and the LTO has a relative higher potential vs. Li/Li+so is safe for the TPU electrolyte. The all-solid-state cell could be a promising candidate power source for the flexible electronic devices.
(1) Zhou, G.; Li, F.; Cheng, H.-M. Energy & Environmental Science
2014, 7, 1307.
(2) Bachman, J. C.; Muy, S.; Grimaud, A.; Chang, H.-H.; Pour, N.; Lux, S. F.; Paschos, O.; Maglia, F.; Lupart, S.; Lamp, P.; Giordano, L.; Shao-Horn, Y. Chemical Reviews
2016, 116, 140.

Figure 1
Gel Electrolytes Incorporated with Graphene-Oxide Quantum Dots for High Performance in Lithium Ion Batteries
Authors: Chen Yen-Ming , Teng Hsisheng 
Published: February 2020

This study incorporates graphene oxide quantum dots (GOQDs) in to a gel polymer electrolyte (GPE) designed for lithium ion batteries (LIBs). The GPE comprises poly(acrylonitrile-co-vinyl acetate) copolymer (PVA) blending poly(methyl methacrylate) (PMMA) as a host swelled by a liquid electrolyte (LE) of 1-M LiPF6 in a carbonate solvent. The major concerns for GPE-based LIBs is the capacity retention and cycle life under high-rate operation. Among numerous functional polymer segments used for GPEs,1 poly(acrylonitrile) (PAN) exhibits excellent thermal stability, ion-solvating ability, material processibility, and electrochemical stability,2 whereas poly(vinyl acetate) (PVAc) strongly absorbs solvent molecules to facilitate polymer swelling and ion transport. The segmental motion of PVA can be further promoted by blending PMMA; therefore, the polymer framework developed in this study represents an ideal host for GPEs.
Previous studies have used inorganic oxide nanoparticles, such as SiO2, TiO2, Al2O3, ZrO2, as fillers to improve both the mechanical strength and ionic conductivity of GPEs.3 GOQDs,which contain numerous oxygen functional groups on the surface, have strong affinity to polymer chains for uniform dispersion in GPEs. The present study finds that the incorporated GOQDs substantially increase the mobility of lithium ions in the developed GPE by accelerating lithium-ion hopping along the polymer chains. A resulting Li/GPE/LiFePO4 battery delivers a high discharge capacity of 70 mAh g-1 at 17 C-rate, which is much higher than that of a Li/LE/LiFePO4 battery (35 mAh g-1).

References

P. Hu, Y. Duan, D. Hu, B. Qin, J. Zhang, Q. Wang, Z. Liu, G. Cui, L. Chen, ACS Appl. Mater. Interfaces 2015, 7, 4720-4727.

S.H. Wang, P.L Kuo, C.T Hsieh, H. Teng, ACS Appl. Mater. Interfaces 2014, 6, 19360−19370

M. Osińska, T. Jesionowski, K. S-S. Tefańska, M. Walkowiak, Cent. Eur. J. Chem. 2010,8(6),1311-1317

Acknowledgments: This research was supported by the Ministry of Science and Technology, Taiwan (104-2221-E-006-231-MY3, 104-2221-E-006-234-MY3, 105-3113-E-006-005, and 104-3113-E-006-011-CC2), and by the Ministry of Education, Taiwan, The Aim for the Top University Project to the National Cheng Kung University.
Local Mass Transport Resistance of Low-Loaded PEM Fuel-Cell Catalyst-Layers
Authors: Freiberg Anna Teresa Sophie , Schuler Tobias , Tucker Michael C , Secanell Marc , Weber Adam Z 
Published: February 2020

To this day, the content of noble metals in the catalyst layers of proton exchange membrane fuel cells (PEMFCs) is still accounting for up to 60 % of the total stack cost and is therefore needed to be reduced for large-scale applications as automobile industry. Though a lot of effort was put into fabrication of catalyst-layers (CLs) with sufficiently low platinum loading, the performance below a certain content starts to decay rapidly. Within the CL, a complex interplay of mass and charge transport takes place, making the identification and quantification of the limiting parameters especially difficult and laborious. Finally, this resistance was found to be due to a local mass transport resistance scaling inversely with the electrochemical active surface area (ECSA).
In this presentation, the results for the local transport resistance measured in-situ via our unique hydrogen limiting current setup for CLs of varying loading, ionomer content and fabrication are shown. The effects of temperature and relative humidity on this intrinsic property are discussed, allowing a deeper understanding of the processes occurring close to the catalyst surface. Though water production, oxide effects and possible peroxide formation can make oxygen limiting currents hard to quantify in detail, data is included, allowing a direct comparison of the transport properties and pathways of both reactants. The data provided shows the potential of this measurement technic to identify the transport limitations in a fast and easy way, which helps to optimize the electrode structure, composition and fabrication for several operation-conditions and therefore applications.

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Fuel Cell Technologies Program of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and by CRADA agreement LB08003874 between Lawrence Berkeley National Laboratory and Toyota Motor Company.

Figure 1
Achieving Long Life Time Batteries: Understanding and Controlling Non-Faradaic Reactions
Authors: Takeuchi Esther S , Marschilok Amy C , Takeuchi Kenneth J 
Published: February 2020

Characterization of electrochemical properties determines the energy content for new materials and possible viability for a potential application. Equally critical yet more challenging is determining the non-Faradaic parasitic reactions of the active materials in a battery environment and their relationship to useful battery life. In order to be successful in long calendar life battery applications, only very low levels of parasitic reactions can be tolerated. For example, calendar life is a particularly important consideration for implantable medical batteries, especially for devices powering essential life functions such as cardiac rhythm management devices. Determining stability by direct systems level testing is slow and expensive as it can require many years and many batteries to affirm.
The dissolution of cathode materials including manganese, cobalt and vanadium oxides in battery systems has been identified as a specific battery failure mechanism. However, dissolution studies including kinetic analysis of the dissolution of active battery materials in non-aqueous electrolytes are largely absent from the literature. We developed a quantitative approach to assess battery materials for their solubility and then validated the approach with battery testing. In this study, a series of vanadium oxide and vanadium phosphate based cathode materials were studied relative to their dissolution in battery electrolyte. Kinetic analysis of the results provided a quantitative approach for understanding the impact of structure and composition on the dissolution of active materials. Negative electrode surfaces from cells using cathodes displaying different levels of solubility were analyzed. A conceptual model of the negative electrode surface electrolyte interphase was developed to rationalize the observed cell impedance and performance. Implications for lifetime prediction for these and other battery systems will be discussed.
A Computational Analysis of Battery Response during Onset of Internal Short Under Mechanical Abuse Conditions
Authors: Allu Srikanth , Kalnaus Sergiy , Kumar Abhishek , Pannala Sreekanth , Simunovic Srdjan , Wang Hsin , Turner John A 
Published: February 2020

The impact testing of batteries revealed multiple layers of current collectors come into contact leading to internal short. The local short generates large currents and cause immense heat generation. The dynamics of discharge during this internal short process is not completely understood. In this work we present a three-dimensional electro-chemical and thermal model for Li-Ion batteries that captures onset of internal short under mechanical abuse conditions. The governing differential equations are discretized using ﬁnite element method and solved using implicit non-linear solvers with robust stability and convergence. A simulation study of various contact areas for multiple Li-Ion battery capacities is reported.