bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Approach to the Formation of Carbide-Derived Carbons Using NH4Cl
Authors: Remington Emily , Dansereau Spencer , McGlamery Devin , Tatar Greg , Stadie Nicholas , Gannon Paul
Published: February 2020

Carbide-derived carbons (CDCs) are traditionally prepared via high-temperature (>200°C) chlorination (Cl2) of metal carbides for research and commercial applications including supercapacitors. This study investigates an alternative CDC synthesis method using an inexpensive halogen-containing etchant, ammonium chloride (NH4Cl), to produce porous CDCs with tunable microstructures. Metal carbide (MexC) powder was mixed with NH4Cl salt and brought to set temperatures ranging from 300-800°C for 2-15 hrs. Reactor designs consisted of an open, tube or box furnace, system with flowing argon or air environments, or the mixture was sealed in an evacuated quartz ampule with Pair,initial= ~1e-2 mbar and Pmax= 20 bar. Scanning electron microscopy (SEM) images show a developing porous layer on the surface of the MexC particles following the core-shell growth model. Auger electron spectroscopy (AES) of the carbon KLL region was used to determine the resulting allotrope of the MexC-CDC powders. When titanium carbide (TiC) was used as the CDC precursor, AES spectra were indicative of a surface transition from metal carbide to graphitic carbon. Furthermore, preliminary N2 adsorption measurements signified that the MexC mass loss and pore growth was associated with an increase in surface area.
Effect of Cu, Ni Seeds on the Formation of Uniform Ag Layer on PET Film Via Atmospheric Pressure Plasma Reduction
Authors: Oh Hyo-Jun , Dao Van-Duong , Choi Ho-Suk
Published: February 2020

In this study, metal (Cu or Ni) seed is formed on the surface of PET film using atmospheric pressure plasma, and Ag layer is formed on the surface of metal seed / PET film. The morphology of the Ag layer and the electromagnetic interference (EMI) shielding effectiveness (SE) are investigated according to the presence of metal seed and the kind of metal seed precursor. The surface of the PET film is pretreated with an atmospheric plasma, and then a 10 mM metal precursor solution is loaded, dispersed and dried. Thereafter, the metal precursor dried on the surface of the PET film is reduced by atmospheric plasma. As a result, the Ag layers formed on the Cu seed/PET film and the Ni seed/PET film are more uniform and smooth than the Ag layer formed on the surface of the PET film. The former EMI SEs are higher than the latter one. In particular, the highest EMI SE is measured from the Ag layer on a Ni seed/PET film. The results of the present study are expected to lead to the efficient fabrication of metal or alloy layers on the surfaces of polymeric materials with low melting points at a relatively low cost for EMI shielding applications.
Optical and Electrical Properties of ECR-PECVD Grown SiCN Thin Films
Authors: Abdelal Aysegul , Khatami Zahra , Mascher Peter
Published: February 2020

Recent progress in scaling down the metal-oxide semiconductor (MOS) devices accompanied limitations arising from quantum effects, which leads to a search for new materials. Silicon oxide (SiO2) thin films have been a favourable dielectric for more than 4 decades. Their usage have become impractical due to the power dissipation and delay in interconnects. To increase the electrical performance, low extinction coefficient (low-k) dielectric materials are being developed as a substitute to SiO2. Those materials draw considerable attraction due to their advances in the integrated circuit technology to increase the transistor density. Among numerous materials, silicon carbonitride (SiCN), which is an intermediate compound between silicon nitride (SiN) and silicon carbide (SiC), has become noteworthy with its unique properties as low-k, robustness, high thermal stability, and wide bandgap of 2.2eV- 5eV1.

In this work we present the optical, structural, and electrical analysis of SiCN thin films grown using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD). The influence of the precursors (SiH4, C2H2, and N2 gases) on the composition and electronic structure of thin films which were characterized by Rutherford backscattering spectroscopy (RBS) and Fourier transmission infrared spectroscopy (FTIR). Furthermore, current-voltage characteristics were studied in dark and illuminated environment at room temperature. We studied the variation of photodiode characteristics with the thin film compositions. These results were also compared with the SiCN thin films growth using identical parameters except for the carbon source (CH4 gas) which has been reported in earlier studies2. Our findings showed that the hydrogen content influenced the optical coefficients of these two set of samples. Index of refraction and extinction coefficients were characterized by variable angle spectroscopic ellipsometry (VASE). In addition to our works on developing low-k matrix to enhance the performance of the integrated circuits, the wide gap feature of SiCN thin films enable us to consider the ultraviolet (UV) photo responsivity effect which is studied for photodetector device application.

References:

[1] B.P. Swain, N.M. Hwang, Appl. Surf. Sci. 254 (2008) 5319

[2] Z. Khatami, P.R.J. Wilson, J.Wojcik, P. Mascher, Thin Solid Films 622 (2017) 1–10
Morphology Matters: Additive-Assisted Metal Foam Deposition for the Electrochemical CO2 Conversion
Authors: Dutta Abhijit , Rahaman Motiar , Morstein Carina , Schlegel Nicolas , Broekmann Peter
Published: February 2020

High-surface area metal foam catalysts for the electrochemical CO2 reduction reaction (ec-CO2RR) are deposited on planar model substrates and technical supports (e.g. 2D mesh or 3D sponges). The metal deposition is typically carried from acidified plating baths at particularly high current densities (e.g. -3 A/cm2) where the metal deposition is superimposed on the hydrogen evolution reaction (HER). Gas bubbles formed on the support surface serve as geometrical template for the metal deposition leaving highly porous metal foams behind.1,2 Pore density and the particular side-wall morphology of these foams can be fine-tuned not only by the current density, metal ion concentration in solution but also by the use of particular polymeric plating additives (e.g. polyethylene-imines, PVPs, polymerizates of imidazole and epichlorohydrin). The activity and product selectivity of the electrochemical reduction of CO2 on Cu foam catalysts strongly depend on the resulting pore size distribution of the Cu catalyst. The maximum in the C-C coupling efficiency (FEC2 = 55%) observed for pore size dimensions in the range of 50 to 100 µm. Such morphology dependence of the ec-CO2RR product distribution will be discussed not only on the basis of the availability of certain reactive surface sites and facets but also on the basis of a temporal trapping of gaseous intermediates (in particular CO and C2H4) inside the mesoporous catalyst material. Mild thermal annealing (300°C, 1h) of the Cu metal foams activates them for the production of C2 and C3 alcohols (ethanol, n-propanol). Identical location (IL) HR-SEM, HR-TEM, white-light interferometry and 3D optical microscopy are applied to probe morphological changes on different length scales that are induced by the foam activation (e.g. by thermal annealing) and the ec-CO2RR itself. This study indicates that the catalyst morphology might undergo drastic changes under operando conditions.

[1] Shin, H. C.; Liu, M. L., Chem. Mater.
2004,
16 (25), 5460-5464.

[2] Shin, H. C.; Dong, J.; Liu, M. L., Adv. Mater.
2004,
16 (3), 237-240.
(Invited) One Step Synthesis of Li-Alkyl Carbonates and Their Applications As Coatings on Li Anode
Authors: Liu Haodong , Zhou Hongyao , Xing Xing , Yan Qizhang , Lee Byoung-Sun , Lim Hee-Dae , Gonzalez Matthew , Liu Ping
Published: February 2020

Lithium metal is being extensively studied as an anode to replace graphite due to its high capacity and the lowest negative electrochemical potential.1 Current research focus is to mitigate lithium dendrite growth and to increase coulomb efficiency during electrochemical cycling by using various surface coatings or electrolyte additives. Due to the complex reduction reactions of electrolyte components on lithium metal surface, it is highly desirable to develop coating materials with high electrochemical stability.

In this work, we report the synthesis of several Li-alkyl carbonates via a simple one step reaction. These carbonates are known components of solid electrolyte interface (SEI) layers on lithium and graphite anode surfaces. The chemical composition and structural information of these synthetic Li-alkyl carbonates are identified by X-ray diffraction and Infrared Spectroscopy. In one implementation of the reaction, a single-component coating is formed on Li metal in a LiI/organic carbonates (dimethyl carbonate (DMC) and ethylene carbonate (EC)) electrolyte. LiI chemically reacts with dimethyl carbonate to form lithium methyl carbonate, which precipitates and forms a chemically homogeneous coating layer on Li surface. This coating layer is shown to enable dendrite free Li cycling in a symmetric Li||Li cell even at a current density of 3 mA cm-2. Adding EC to DMC modulates the formation of the lithium methyl carbonate, resulting in a stable coating layer which is essential for long term Li cycling stability. Fig.1 shows the morphology of deposited Li using LiI-EC/DMC electrolytes.2 Furthermore, the coating can enable dendrite free, high coulomb efficiency cycling after being transferred to common LiPF6/carbonates electrolytes which are compatible with metal oxide cathodes. We will show that LiI reacts with a broad range of organic carbonates and ethers to form lithium compounds relevant to high efficiency operations of battery anodes.

Acknowledgements

This work was supported by the Office of Vehicle Technologies of the U.S. Department of Energy through the Advanced Battery Materials Research Program (Battery 500 Consortium) under Contract DE-EE0007764.

Reference

W. Xu, J. L. Wang, F. Ding, X. L. Chen, E. Nasybutin, Y. H. Zhang and J. G. Zhang, Energ Environ Sci, 2014, 7, 513-537.

H. D. Liu, H. Y. Zhou, B. S. Lee, X. Xing, M. Gonzalez and P. Liu, ACS Appl Mater Inter, 2017, 9, 30635-30642.

Figure 1
Redox Flow Battery Electrolyte Design Formulations: Molecular Screening and Engineering
Authors: Murugesan Vijayakumar , Wei Xiaoliang , Hollas Aaron , Nie Zimin , Li Bin , Sprenkle Vincent , Reed David , Wang Wei
Published: February 2020

Redox flow battery (RFB) offers great promise to provide transformational progress for large-scale energy storage technology. As the energy-bearing redox active species are dissolved and externally stored in liquid electrolytes, their physiochemical properties dictate the energy density, specific capacity, and cycle life thereby become a single most critical component of RFB. For instance, the concentration and chemical stability of redox active species within the electrolyte will determine the system-specific energy density and temperature window for the RFB operation, respectively1. With the growing interest in developing sustainable RFB systems, there is a pressing task to identify the optimal electrolyte. This led to an active search for an ideal electrolyte which can hold a higher concentration of redox active species with wide chemical and thermal stability. Most electrolyte research has been focused on the empirical study of the effects of the pH, additives and solvent composition2. Using combined spectroscopic and computational studies we established an electrolyte design formulation based on molecular solvate structure tuning3, 4. This helps us to optimize the solubility and redox potential of redox molecule, exemplifying a generic electrolyte design strategy for RFB (see Figure 1). In this presentation, we will discuss the virtual screening and electrolyte design procedures for selecting functional moieties, additive salt and co-solvent to enhances the much-needed redox molecule solubility and stability.

References

M. Vijayakumar, W. Wang, Z. Nie, V. Sprenkle and J. Hu, Journal of Power Sources 241, 173-177 (2013).

M. Vijayakumar, Z. Nie, E. Walter, J. Hu, J. Liu, V. Sprenkle and W. Wang, ChemPlusChem 80 (2), 428-437 (2015).

K. S. Han, N. N. Rajput, M. Vijayakumar, X. L. Wei, W. Wang, J. Z. Hu, K. A. Persson and K. T. Mueller, J Phys Chem C 120 (49), 27834-27839 (2016).

L. Li, S. Kim, W. Wang, M. Vijayakumar, Z. Nie, B. Chen, J. Zhang, G. Xia, J. Hu, G. Graff, J. Liu and Z. Yang, Advanced Energy Materials 1 (3), 394-400 (2011).

Figure 1
Biosensor with a 4-Channel Disposable Sensing Module Facilitating a Direct Sensitive Detection of Colon Cancer Biomarkers in Serum
Authors: Park Sungwook , Jeun Minhong , Lee Kwan Hyi
Published: February 2020

Colon cancer has a survival rate of 90% or more when detected early, but the current clinical diagnostic methods of identifying colon cancer such as optical screening and biopsy for polyp samples have difficulties in early diagnosis due to low sensitivity and complex process. In this study, we developed a field-effect transistor(FET)-based biosensor with high sensitivity and specificity to quantitatively analyze colon cancer biomarkers in serum samples. Conventional FET-based sensors have limitations to detect target molecules in serum due to short Debye length and high noise signal from high concentrations of ions and many interfering species. In this study to circumvent these issues we propose a new dual-gate FET based biosensors featuring 4-channel disposable sensing module(DSM). We successfully demonstrated that our new biosensor can facilitate a fg/ml level detection of biomarkers in serum.
(Invited) Flexible Triboelectric Nanogenerator and Highly Sensitive Pressure Sensor
Authors: Fan Fengru
Published: February 2020

Transparent electronic devices built on flexible substrates are expected to meet emerging technological demands for the next generation of flexible electronic and optoelectronic devices. A suitable energy source is a vital part for realizing fully self-powered systems. Energy harvesting and conversion technology from environment in which the system will be deployed is a promising route. Recently, we have introduced a new concept

on the basis of triboelectrification and electrostatic induction for successfully converting mechanical energy into electric energy at an energy conversion efficiency as high as 50%. Subsequently, transparent triboelectric nanogenerators (TENGs) using indium tin oxide (ITO) or graphene as electrodes have been demonstrated, which are the only possible power source that light can penetrate through. However, there is a need for a low-cost and large area compatible technology for producing transparent TENGs with high-output power supply, aiming for applications

such as touch screens.

In our previous work, we fabricated a transparent TENG and pressure sensor by using polyester (PET) and polydimethylsiloxane (PDMS) films as flexible substrates to integrate ITO electrodes. It has also been demonstrated that the patterned surface is an effective method to improve the output performance of the TENG. However, realizing such a structure is not trivial in mass production and the patterned structure will reduce the transparency of the device due to the light scattering effect. Here, we present a simple, cost-effective and large-scalable method for fabrication of highly transparent TENGs.

Although triboelectric effect has been known for thousands years, the underlying mechanism is actually very complex and still under debating. The competing possible mechanisms appear to include electron transfer, ion transfer, bond dissociation, chemical changes, and material transfer, and it is likely that different mechanisms may be involved depending on the specific materials and environmental conditions. Usually, it needs specialized equipment to characterize the charged surface and study the mechanism. It is worth noting that the output performance of TENG can directly reflect the capacity of the triboelectrification. Herein, we use this feature to investigate the mechanism of the triboelectrification by examining various factors on the performance of TENG.

Furthermore, another meaningful outcome of our study is that we explore the mechanism from the microscopic and molecular perspective using the methods for surface characterization, which would be beneficial to the improvementand application of TENG at a large scale.

References

F. R. Fan, Z. Q. Tian, Z. L. Wang, Nano Energy 2012, 1, 328-334.

F. R. Fan, L. Lin, G. Zhu, W. Z. Wu, R. Zhang, Z. L. Wang, Nano Lett. 2012, 12, 3109-3114.

F. R. Fan, J. J. Luo, W. Tang, C. Y. Li, C. P. Zhang, Z. Q. Tian, Z. L. Wang, J. Mater. Chem. A 2014, 2, 13219-13225.
(Invited) High-Performance Carbon Nanotube Based Flexible Electronics for Integrated Smart Sensor System
Authors: Hu Youfan
Published: February 2020

As the information processing part in flexible integrated sensor systems, there are several basic requirements for the integrated circuits (ICs) in addition to flexibility, including high speed, low power consumption, medium to large scale integration, etc. Currently there is no solution that can meets all the requirements. Here we present our recent progress in high-performance flexible thin film transistors based on carbon nanotube (CNT). The transistors exhibit large on-state current, high mobility (>80 cm2V-1s-1), small subthreshold slop (<70 mVdec-1), and large current on/off ratio (>105), all with an operating voltages of 2 V. The developed fabrication approach presents high yield and the transistors’ performances are highly uniform with well controlled threshold voltage distribution, which enable the realization of various logic gates and the most complex CNT-based ICs on flexible substrate. Finally, an integrated smart sensor system with in-situ signal processing capability for human body monitoring based on CNT was demonstrated.
(Invited) Large-Area Solution-Nanomanufactured Air-Stable 2D Material for High-Performance Electronics and Smart Sensors
Authors: Wu Wenzhuo
Published: February 2020

The reliable production of two-dimensional (2D) crystals is essential for exploring new science and implementing novel technologies in the 2D limit. However, ongoing efforts are limited by the vague potential in scaling-up, restrictions on growth substrates and conditions, small sizes and/or instability of synthesized materials. In this talk, I will discuss our recent progress in the fabrication of large-area, high-quality 2D material by a substrate-free solution process. The crystals exhibit process-tunable thicknesses from a monolayer to tens of nanometers, and lateral sizes ~ 100 um. Our prototypical 2D transistor device, which is air-stable, shows an excellent all-around figure of merits compared to existing 2D materials. We further carry out the first experimental exploration of piezotronic effect in such solution-grown 2D material and systematically investigate the piezotronic transport properties. The coupling between the piezoelectric and semiconductor properties in such material system enables the design and implementation of novel electronic devices and smart sensors that can interact with the mechanical stimuli. Our approach has the potential to produce stable, high-quality, ultrathin semiconductors with a good control of composition, structure, and dimensions for applications in electronics, optoelectronics, and energy devices.
(Invited) Wearable and Flexible Bio-Electronics Enabled By 'crack'-Driven Transfer Printing Methods
Authors: Lee Chi Hwan , Kim Min Ku , Wie Dae Seung , Kim Hyungjun
Published: February 2020

Emerging transfer printing methods provide means to build a range of mechanically flexible and wearable bioelectronics, opening up a new prospect in the field of biomedical technologies. The mechanical flexibility allow the devices to intimately integrate with biological systems such as biological cells, tissues, and/or the skin at their length scale. The embedded semiconducting nanomaterials provide the electronic functionalities that can monitor and/or stimulate them with spatial and temporal controls. This presentation will talk about a novel class of transfer printing method by exploiting controlled “crack” that is capable of liberating various nanoelectronics from their native wafer over large scale. The liberated nanoelectronics can be then thinly placed onto an arbitrary surface of biological systems of interest including cells and tissues, and therefore can provide the desired electronic functionalities at the intimate interface. A multiscale computational model that incorporates atomistic debonding mechanisms into macroscale interface delamination reveals the underlying working mechanisms and provide a quantitative guidance for controllable cracking process. The knowledge obtained from these studies provides important insights to improve the manufacturability in terms of scalability, controllability, and reproducibility. System-level demonstrations include skin-mountable sensors and cell-injectable silicon nano-needles, which can validate their utility in wearable healthcare systems and intracellular drug delivery platform. Discussions about the results of detailed experimental and theoretical studies will follow to reveal the essential attributes of the materials, devices, and fabrication process.
Mesoporous Metal Electrocatalysts for the Oxygen Evolution Reaction
Authors: Hayashi Akari , Muto Marika , Sasaki Kazunari
Published: February 2020

Introduction

Development of anode electrocatalys for the PEM type water electrolyzer is challenging since carbon supports cannot be used in order to disperse small catalyst particles under the high potential condition over 1.5 V. Without carbon supports, electrocatalysts result in relatively low active surface area and low activity. Our group has been working on mesoporous materials for PEFC and has found that mesoporous materials can keep their porous structure even after being built into the device. Based on the similar idea used in our PEFC studies, we propose development of carbon-free mesoporous metal electrocatalysts with high active surface area to increase the efficiency of water electrolyzer cells. In this study, mesoporous platinum and iridium materials were particularly developed, and their oxygen evolution reaction (OER) activity was evaluated.

Experimental method

Mesoporous platinum and mesoporous iridium materials were synthesized using Pt(acac)2 or Ir(acac)3 as a metal precursor and Pluronic F127 as a surfactant. After mixing the surfactant and metal precursor, the resulting mixture was heated up under N2 or Air atmosphere to decompose Pluronic F127 and make the mesoporous structure. Their electrochemical measurements were performed using a common half-cell setup in the solution, in order to evaluate OER activity. The durability against high potential like 1.8 V was also analyzed.

Results and discussion

The resulting platinum and iridium materials were confirmed to have the randomly oriented porous structure constructed by aggregation of Pt and Ir/IrOx nanoparticles, respectively. The pore diameter was found mostly smaller than 100 nm. With these porous metal materials, OER activity was evaluated.

Regarding platinum based materials, the initial activity resulted in the same as a standard Pt/KB electrocatalyst, TEC10E50E, even though ECSA was six times higher for Pt/KB. However, for their durability, as expected, Pt/KB lost most of OER activity owing to carbon corrosion. Consequently, carbon-free porous Pt electrocatalyst with high activity and durability was successfully prepared. Similarly, a porous iridium electrocatalyst has been prepared, and its OER activity will be discussed.
Electrostatic Spray Deposited Sn-SnO2-CNF Composite Anodes for Lithium Ion Storage
Authors: Rabiei Baboukani Amin , Adelowo Ebenezer , Agrawal Richa , Khakpour Iman , Drozd Vadym , Li Wenzhi , Wang Chunlei
Published: February 2020

Metals and metal oxides as anode materials for Li-ion batteries and supercapacitors are of significant interest to many potential technologies because of their high theoretical capacity value, low price, and environmentally friendly features. In spite of these considerable benefits and ongoing progress in the field, momentous challenges exist, especially structural disintegration due to volume expansion of electrode materials. In this study, the direct synthesis of electrospun tin based composite with CNF prepared directly on a nickel foam current collector using the electrostatic spray deposition (ESD). This binder free approach provides some advantages such as the controllability of the nanostructure morphology and scalable manufacturing capabilities. The electrochemical performance of the Sn-SnO2-CNF composite synthesized by electrostatic spray deposition as an anode material for Li-ion batteries were evaluated by cyclic voltammetry and charge-discharge experiments. The composite material showed large discharge capacity of 1117.5 mAhg-1 after 30 cycles and also a high rate capability. In this presentation, the cycling stability and rate capability of samples will be presented in a half-cell assembly against Li/Li+. Moreover, the feasibility of creating anodes and the results of characterization of the active materials will be discussed.

Figure 1
Composite Graphene/Blended Polymer of PEO/PVDF-HFP As Solid Polymer Electrolyte for Sodium Batteries
Authors: Le Phung My Loan , Vo Thanh Duy , Do Nguyen Hoang , Nguyen Hanh Thi Tuyet , Phung Trung Minh , Man Tran Van
Published: February 2020

Solid polymer electrolytes (SPEs) are promising candidates for their application in electrochemical devices owing to its thermal and mechanical stability for application purposes [1-3]. The ionic conduction in polymer electrolytes occurs in amorphous phase where the ionic motion is coupled with the segmental motion above glass transition temperature. Among various polymers, the polyethylene oxide (PEO) has been studied extensively so far due to its high mechanical property and low barriers to bond rotation with ion efficiency [4,5]. Recently, the poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) has also greatly attracted as a polymer matrix with which provides mechanical stability (by PVdF) and improves ionic conductivity (by HFP component) [6-8]. In this work, we employed the blending polymer of PEO and PVdF-HFP to create a SPEs for sodium-ion battery application. Graphene addition aims to enhance ionic conductivity and mechanic properties of SPEs. Structure and morphology of polymer electrolytes were characterized by X-rays diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal properties of membrane were analyzed using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Ionic conductivity and electrochemical stability of polymer membranes were also studied using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). The battery performance was evaluated based on charge/discharge curve and sodium intercalation/deintercalation process. A comparison between Na-ion and Li-ion battery using SPEs was also performed.

References:

[1]. F. M. Gray F M (ed), Solid Polymer Electrolytes–Fundamentals and Technological Applications (New York: VCH), 1991.

[2] G. Mao, R.F. Perea, W.S. Howells, D. L. Priceand, M.L. Saboungi, Nature, 405 (2000), 163.

[3] J.Y. Song, Y. Y. Wang, C.C. Wan, J. Power Sources, 77 (1999),183.

[4] G.S. MacGlashan, Y.G. Andreev, P.G. Bruce P G, Nature 398 (1999), 792–794.

[5] S. Das, A. Ghosh, Electrochim. Acta 171 (2015), 59–65.

[6] R. Miao, B. Liu, Z. Zhu, Y. Liu, J. Li, X. Wang, Q. Li, J. Sources 184 (2008), 420–426

[7] S. Ramesh, S-C. Lu, I. Vankelecom, J. Phys. Chem. Solids 74 (2013), 1380.

[8] S. Ramesh, S-C. Lu, J. Mol. Liq. 177 (2013), 73

Acknowledgements:

This research is funded by VietNam National Foundation for Science and Technology Development supported (NAFOSTED) under grant number 104.03-2012.46 and Viet Nam National University of Ho Chi Minh city through.
Solid Electrolyte Interphase and Nitrogen Doping Effect on Potassium Storage Mechanism in Graphite
Authors: Wang Huanhuan , Liu Jilei , Shen Zexiang
Published: February 2020

The inferior cycling stability critically impedes the development of potassium-ion batteries (KIBs). The solid electrolyte interface (SEI) for nitrogen doped graphite foam (NGF) was studied in both KPF6 and KN(SO2F)2 (KFSI)-based organic electrolytes, aiming to unravel the SEI effect on K+ ion storage mechanism. Electrochemical characterizations disclose that the KN(SO2F)2-based cells deliver improved electrochemical performance in terms of reversibility and cycling stability, compared to KPF6 based cells. Experimental results including depth-profiling XPS and FTIR spectra, together with the theoretical calculations, reveal that (CH2OCO2K)2, C2H5OCO2K, KF and K2CO3 are the dominant components of SEI layers in both electrolytes. Particularly, the amount of K2CO3 in KPF6-based electrolyte is much more than that in KFSI-based electrolyte, resulting in inferior stability. Moreover, the depth-profile XPS results indicate that the SEI formed in KFSI based electrolyte is much more stable, compact and thinner than that in KPF6 based electrolyte. All these features, together, ensure good stability and high reversibility in KFSI-based electrolyte.

The nitrogen doping effect on K+ ion storage was also explored. Enhanced electrochemical performance was identified upon increasing the nitrogen content, due to i) the enrichment of active sites for K+ ion storage and ii) the improved electronic conductivity. Moreover, the electrochemical performance is strongly dependent on N-doping types. Specifically, the pyridinic nitrogen dominates the reversible capacity, as identified by the presence of critical point at 4.29 at. %. In which, the atomic ratio of pyridinic N in NGF is 2.53 at. %, which is higher than that of 7.03 at. %, with only 2.16 at. % pyridinic N. The result is consistent with the theoretical study, which verifies that the charge transferred from K ions to NGF increases with the pyridinic nitrogen doping. Our results promote better understanding of K+ ion storage mechanism in graphite and provide invaluable guidance for optimized carbon-based electrode design for high-performance KIBs.
Effect of Electrolyte Composition on the Solid Electrolyte Interface (SEI) and Electrochemical Cycling of Lithium Metal Anodes
Authors: Lucht Brett L , Brown Zachary Lee , Jurng Sunhyung
Published: February 2020

The role of the electrolyte composition in the formation and evolution of the solid electrolyte interface (SEI) on lithium metal anodes will be reported. A systematic investigation of the effect of composition of carbonate based electrolytes (salt, solvent, and additive) on the electrochemical performance of lithium metal anodes has been conducted. Electrolytes have been investigated in both Li/Li symmetrical cells and in Cu/LiFePO4 cells. The electrochemical performance of the cells is highly dependent upon the composition of the electrolyte. Optimization of the electrolyte composition results in dramatic improvement of the cycling performance of the lithium metal anodes. The structure and composition of the SEI for different electrolyte compositions has been investigated via a combination of Infrared spectroscopy with attenuated total reflectance (IR-ATR), X-ray photoelectron spectroscopy (XPS), and Transmission Electron Microscopy (TEM). The ex-situ surface analysis suggests a strong correlation between SEI structure and electrochemical performance.
Fluoroethylene Carbonate-Based Organic Electrolyte Solution for Very Stable Lithium Metal Stripping−Plating at a High Rate and High Areal Capacity
Authors: Aurbach Doron , Markevich Elena , Salitra Gregory
Published: February 2020

High theoretical specific capacity (3860 mAh g−1) and low negative redox potential make lithium metal an ideal anode for high-energy-density Li batteries. However, dendrite growth and side-electrolyte solution reactions limit the cycling life of the batteries with Li metal anode and cause severe safety problems, hindering practical use of these anodes. Many efforts have been made to stabilize Li metal anodes, including modification of the

Li surface by various mechanical, physical, and chemical techniques, increase of the effective Li-electrode surface by use of an anode matrix with a very large surface area, the use of solid electrolytes, the addition of selected cations (such as cesium or rubidium) which protect the Li surface from dendrite formation according to the self-healing electrostatic shield mechanism and the use of functional electrolyte additives for the in situ formation of a protective SEI. We demonstrate excellent cycling performance of Li metal anodes in EC-free FEC based organic carbonate electrolyte solutions, which were shown to be the most promising electrolyte solutions for high energy-density and high-voltage rechargeable Li batteries. Symmetric Li|Li cells demonstrated an extremely long cycle life and a stable voltage profile for more than 1100 cycles at a current density up to 2 mA cm−2 and an areal capacity of 3.3 mAh cm−2 with a minimal amount of electrolyte solution, sufficient for wetting the separator in coin cells (50 μl/cell or 22 μl cm−2). An increase in areal capacity up to 6 mA h cm−2 does not affect the shape of the voltage profile of the symmetric Li|Li cells. The use of the FEC-based electrolyte made it possible to obtain stable cycling of Li|NMC cells for hundreds of cycles with high loading of active cathode material with areal capacity of 3.3 mAh cm−2. We attribute the high performance of the Li anodes to the formation of a stable and efficient SEI on the surface of the Li metal electrodes cycled in FEC-based electrolyte solutions. The composition of the SEI is analyzed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.
Redox-Mediated Iron Phthalocyanine Hybrid Electrocatalyst for Lithium-Oxygen Battery Application
Authors: Nahm Kee Suk
Published: February 2020

We report a redox-mediated hybrid electrocatalyst for lithium-air battery using a soluble iron phthalocyanine catalyst combined with hierarchically porous air cathode. A simple and cost-effective technique is utilized to prepare carbon-iron phthalocyanine composites. Furthermore, ball milling effect on catalytic activity of the composite is highlighted. The perovskite La0.6Sr0.4CoO3-δ, which is an effective oxygen evolution reaction catalyst, is also combined with the iron phthalocyanine to prepare a redox-mediated hybrid electrocatalyst. The prepared iron phthalocyanine-carbon and the perovskite La0.6Sr0.4CoO3-δ-iron phthalocyanine composites exhibit better catalytic activity in both oxygen reduction and oxygen evolution reaction than Pt/C, with low overpotential (0.7 V) and 100% reversibility in the tested lithium-air battery.
Scalable Sponge-like Silicon Nanostructures-Based Anodes for High-Capacity Lithium Ion Batteries
Authors: Schneier Dan , Peled Emanuel , Patolsky Fernando , Golodnitsky Diana , Menkin Svetlana , Davidi Guy , Harpak Nimrod , Mados Edna
Published: February 2020

We report on the scalable synthesis and characterization of novel architecture three-dimensional high-capacity amorphous Silicon Nanostructures (SiNSs)-based anodes, with focus on studying their electrochemical degradation mechanisms. By using our novel, low cost and high mass loading chemical vapor deposition (CVD) procedure we synthesized anodes that have shown stable cycle life for up to hundreds of cycles and provided capacities of up to 5.5mAh/cm2, very low irreversible capacity and good compatibility with commercial cathodes such as NCA and LFP. Notably, it was found that the growth of the continuous solid electrolyte interphase (SEI) layer thickness, and its concomitant increase in resistivity, represents the major reason for the observed capacity loss of the SiNSs-based anodes. Since, according to our previous studies, artificial SEI layer may stabilize the SEI formation and growth, thin uniform coatings of Al2O3 was applied directly on the SiNS by a process of atomic layer deposition (ALD). The performance of alumina ALD coated SiNSs-based anodes is presented. Our data reveals that NSs-based anodes of novel architecture are expected to meet the requirements of lithium-ion batteries for both portable and electric-vehicle applications.
Si Anode Materials for Li-Ion Batteries
Authors: Carroll Kyler J. , Li Bin , Strand Dee
Published: February 2020

Silicon is regarded as one of the most promising anode materials because of its theoretical specific capacity (4200mAh/g) compared to commercially available graphite anodes (370mAh/g). However, Si electrodes suffer considerable volume expansion of up to 300% during electrochemical lithiation, leading to electrode cracking and pulverization of the Si, causing rapid capacity degradation. Various approaches had been used for using nanostructured Si materials have been applied to solve this problem, since the interval distance between nano structures and internal spaces in them can act as structural buffer space to accommodate the volume expansion of Si. Although some of the nanostructured Si materials achieved considerably high capacity and cyclability, they are usually prepared by complicate and high cost synthetic process which are difficult to extend to large scale. The other approach is using active/inactive alloys as an efficient way to reduce volume expansion and improve cycling performance. The volume expansion of Si can be suppressed by the presence of inactive components, resulting in the maximum energy density at a given volume expansion. Literature has also shown commercially available and low-cost Si alloys can serve as high capacity Li-storage anodic host materials with certain cyclability. If such Si alloy compounds can be made with required chemical stoichiometry and structural architecture though a simple mechanochemical process.

Wildcat Discovery Technologies is developing facile synthesis pathway to prepare Si-alloy active/inactive material. Our approach utilized high-throughput combinatorial research to optimize synthesis process, Si-alloy composition and electrode component to improve the cycling performance of the anode material. Here we demonstrate that with optimized synthesis process, varied active Si and inactive alloy composition reveal a strong correlation between capacity and cyclability.
Characterization of the Intrinsic Thermal and High-Voltage Stability of Organosilicon-Containing Electrolytes
Authors: Guillot Sarah Lucienne , Usrey Monica Lee , Peña Hueso Adrián , Hamers Robert J
Published: February 2020

Lithium-ion batteries are increasingly used as energy storage devices today due to their excellent energy capacity and voltage characteristics. However, the limited window of electrochemical stability for lithium-ion battery electrolytes constrains the development of devices with higher voltages and longer lifetimes. Conventional carbonate electrolytes degrade under conditions of high heat or voltage to form electrode surface films, leading to capacity fade, impedance increase, and reduced performance over time. Additionally, these electrolytes present a safety risk due to degradation at high temperatures. Therefore, the development of electrolyte systems with increased thermal and electrochemical stability is a relevant issue in battery development.

Organosilicon solvents for battery electrolytes, developed by Silatronix, Inc. with the University of Wisconsin-Madison, have demonstrated improved oxidative stability, reduced gassing, and increased thermal stability. Our work characterizes the thermal and electrochemical behavior of these organosilicon electrolytes by accelerated aging with high heat and extreme potentials. We show evidence of inhibited thermal degradation and propose mechanisms for protection of the lithium salt in organosilicon electrolytes. We identify mechanisms of electrochemical stability and degradation at high voltages against model platinum electrodes. Electroanalytical voltammetry shows increased oxidative stability of the organosilicon electrolytes compared with carbonates. Multinuclear NMR is used to identify and quantify the soluble post-mortem electrochemical products. Voltage and electrolyte composition dependence of surface film product are tracked by x-ray photoelectron spectroscopy. These investigations of solvent-mediated mechanisms of enhanced electrochemical stability enable the future development of advanced high stability electrolytes.
Lithium-Oxygen Batteries with Ultrahigh Areal Capacities: Critical Roles of Air Cathode Architecture
Authors: Lin Yi , Kim Jae-Woo , Connell John W.
Published: February 2020

Lithium-oxygen (Li-O2) battery systems are known to have a high theoretical energy density that surpasses that of lithium ion batteries. If successfully developed, these batteries could find uses in applications with high energy demand such as future electric aircraft. However, many challenges still remain, including the air cathode’s intrinsically sluggish discharge and charge reaction rates that limit performance, round trip efficiency, and Coulombic efficiency, as well as many problems associated with the lithium anode (such as dendrite formation) and the electrolyte (such as instability at high voltage).

Most research on the air cathode of non-aqueous Li-O2 batteries has focused on the choice of materials or catalysts that would improve the battery performance. However, the total capacities (best reflected by areal values) of the air cathodes are often low, typically limited by the areal mass loading, mostly less than 0.5 mg/cm2, making it inefficient for practical applications. However, with the increase of the mass loading, the mass transport through the cathode thickness becomes more limited. Therefore, the cathode architecture to enable optimal battery reactions across the entire thickness is critical. Here we present an ultrahigh areal capacity air cathode platform based on holey graphene’s unique dry compressibility, which circumvents the mass loading limitation of current cathode architecture. The facileness in the solvent-free fabrication process of the cathode allows many different designs of the dense, but breathable air cathode architectures with ultrahigh areal loadings (on the order of 10 mg/cm2) and excellent battery performance in capacity, round trip efficiency, and cyclability.
Co0.5Mn0.5WO4 as a New Bifunctional Cathode for Non-Aqueous Li-O2 Batteries
Authors: K Guruprakash , Prakash A.S.
Published: February 2020

Li-O2 batteries gained enormous interest in last few years for their attractive theoretical energy density compared to state-of-the-art Li-ion batteries. However, insulating discharge product, Li2O2 causes the large over potentials upon charge resulting in a lower energy round trip efficiencies. Using an efficient bifunctional catalyst can reduce the overpotentials of oxygen reduction and evolution reactions in Li-O2 battery. Herein, we report poly anion (tungstate) based new breathing electrode with low energy surface planes, synthesized by simple hydrothermal route. Co0.5Mn0.5WO4 has demonstrated great ability to catalyze both the OER and oxygen reduction reaction (ORR) with a combined bifunctional overpotential of 0.89 V in alkaline conditions. In line with this, cobalt manganese tungstate catalyst showed excellent electrochemical performance as a cathode in Li-O2 battery, with good rate capability and long cycle life (100 cycles at limited capacity of 1000 mAh/g). X-ray diffraction and FESEM techniques are used to confirm the reversible formation of Li2Ox during battery cycling in 1M LiTFSi-TEGDME electrolyte. Replacing an optimum amount of Co by Mn in CoWO4, tunes the electronic structure, enhances the bifunctional activity for lithium oxide formation-decomposition. Improved cyclability is attributed to enhanced solubility of discharged products on low energy surface planes of nano sized Co0.5Mn0.5WO4.
Understanding Coulombic Efficiency Losses in Lithium Metal Anodes through Operando X-Ray Diffraction
Authors: Geise Natalie R , Kasse Robert M , Steinrueck Hans-Georg , Toney Michael F
Published: February 2020

Next-generation batteries will require higher energy densities, cyclability, safety, and affordability to adequately meet energy storage needs. Li-metal is a promising, high-capacity anode that can be incorporated into Li-ion, Li-S, and Li-air systems. However, the loss of lithium into the solid electrolyte interphase (SEI) and into lithium deposits that become electrically disconnected (‘dead’ Li) are major, interrelated contributors to Coulombic efficiency losses in the Li-metal system. In this work, we use a custom-designed electrochemical cell to measure the XRD throughout plating and stripping of lithium onto a copper substrate to monitor the presence of lithium and crystalline SEI components during cycling. We obtain quantitative results on dead lithium development, which we compare to Coulombic efficiency measurements. Our results show variations in dead lithium formation in across different electrolytes and cycling conditions. Further understanding of capacity loss in lithium metal anodes is likely to lead to better-designed protection layers and electrolytes which improve anode performance.
Li Storage in a Low Intercalation Potential Li2TiSiO5
Authors: Xia Yong-Yao
Published: February 2020

Today’s anode for lithium ion batteries is dominated by graphite, with a low operate voltage at 0.1 V vs. Li+/Li, easy to format lithium dendrite and cause to safety risk. As an alternative anode material, the “zero-strain” spinel structure Li4Ti5O12 could avoid Li plating with a relative high intercalation potential (1.55 V vs. Li+/Li) and exhibits an excellent cycling stability. However, the slightly low capacity and high voltage of Li4Ti5O12 result in low energy density. Therefore, it is very important, but nevertheless a challenge, to develop a negative electrode material with a large capacity and an intercalation potential below 1 V, but not close to the Li plating potential, to ensure the safety of batteries. Herein, we report a new anode material of Li2TiSiO5 as anode material for LIBs. The electrochemical profile, structure and Li storage mechanism were extensively studied.

The crystal structure of Li2TiSiO5 is illustrated as a layered structure with infinite sheets of distorted TiO6 octahedra and SiO4 tetrahedra, linked by Li atoms. The distorted TiO6 octahedral and SiO4 tetrahedral networks are thought to be the origin of the structural stability of this material. The crystal structure is depicted in Fig. 1b (left) and the details are summarized in Table 1. Along with the refined structure of Li2TiSiO5, the nuclear-density difference (Fourier) map in Fig. 1b (middle) reveals negative nuclear density only at the 4d, 4e, and Ti (2c) sites, implying that lithium can only reside at these sites. The 4e sites are indicated by the yellow balls in Fig. 1b (right). Figure 2 give the typical charge/discharge curve of Li
2TiSiO5 at between 0 and 3 V (vs. Li+/Li), delivers a reversible charge capacity (Li-ion extraction) of 308 mAh/g, with a voltage plateau below 1.0 V.

Fig. 1 (a) Crystal structure characterization of Li2TiSiO5 and (b) typical charge/discharge curve of Li2TiSiO5

Figure 1