bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithium Dendrite Suppressing Effect of Fluoroethylene Carbonate Additive on Surface Patterned Lithium Metal
Authors: Lee Hoogil , Han Taeyeong , Jin Dahee , Lee Yong Min , Ryou Myung-Hyun 
Published: February 2020

Abstract

Due to the highest possible theoretical capacity (3860 mAh g-1 or 2060 mAh cm-3) and the lowest negative electrochemical potential (-3.04 V vs standard hydrogen electrode) lithium (Li) metal has been considered as the promising anode material for achieving a battery of high energy density. Nevertheless, the successful implementation of Li metal in the secondary battery system has been delayed due to the uncontrolled dendrite growth during repeated Li deposition/stripping process, resulting the capacity and safety degradation of battery system.
Recently, our group suggested to use the surface-patterned Li metal to suppress Li dendrite growth though a stamping technique [1-2]. We observed that the surface pattern was filled by granular forms of Li metal when the Li plating was conducted at a high current density condition. These can cause the consumption of large amount of Li ions to form solid electrolyte interface (SEI) on the newly exposed Li metal surface.
Herein, we investigated the Li dendrite impeding effect of FEC on the surface-patterned Li metal during the repeated Li plating processes at high current density. The effect of the FEC additive was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS).

Acknowledgements

This work was supported by the international Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No. 20158510050020).

Reference

1. M.-H. Ryou, and Y. M. Lee, Y. Lee, M. Winter, P. Bieker, Advanced Functional Materials 2015, 25, 834-841
2. J. Park, J. Jeong, Y. Lee, M. Oh, M.-H. Ryou, and Y. M. Lee, Advanced Materials Interfaces 2016, 1600140
Enhanced High-Voltage Stability of LiNi0.6Co0.2Mn0.2O2 Cathode By Using Electrolyte Additive
Authors: Kim Jae-Hee , Pham Hieu Quang , Hwang Eui-Hyung , Kwon Young-Gil , Lee Jung-Gyu , Song Seung-Wan 
Published: February 2020

Demands for high-power and high-energy Li-ion batteries are rapidly increasing for their use in electric vehicles. Nickel-rich three-components oxides of Li(Ni1-x-yCoxMny)O2 (NCM, 1-x-y ≥ 0.5) are one of the promising cathode active materials of high-energy density Li-ion batteries because of higher capacity, operation to higher charge cut-off voltage, lower cost and less toxicity than LiCoO2. However, their high-voltage performance is difficult to achieve due to limited anodic stability of conventional electrolyte above 4.2 V vs. Li/Li+. At such an aggressive charge condition, cathode-electrolyte interfacial reactions often cause a degradation of cathode material and electrolyte consumption by oxidative decomposition, resulting in a rapid performance fade.1-3 To stabilize the high-voltage interface between cathode and electrolyte, efforts such as surface coating of cathode materials with inorganic materials have been made.4 Recently, the use of high-voltage electrolyte additives 1-3 is recognized as efficient and economic, because they form a surface protective layer on the cathode, improve the interfacial stability and prevent further electrolyte decomposition. Here we report the development of a new electrolyte additive for cycling the LiNi0.6Co0.2Mn0.2O2 cathode to the charge cut-off voltage of 4.6 V. ex-situ X-ray photoelectron spectroscopic and Infrared spectroscopic studies on cathode-electrolyte interfacial reaction phenomena would be discussed in the meeting.

Acknowledgements

This research was supported by the Korean Ministry of Trade, Industry & Energy (A0022-00725 & R0004645) and Nano Material Technology Development Program through the National Research Foundation funded by the Ministry of Science, ICT and Future Planning (2009-0082580).

References

1. Y. -M. Lee, K. -M. Nam, E. -H. Hwang, Y. -G. Kwon , S. -W. Song, J. Phys. Chem.
C, 118,10631 (2014).
2. D. T. Nguyen, J. Kang, K. -M. Nam, Y. Paik, S. -W. Song, J. Power Sources,
303,150 (2016).
3. H. Q. Pham, K. -M. Nam, E. -H. Hwang, Y. -G. Kwon, H. M. Jung, S. -W. Song, J. Electrochem. Soc.,
161, A2002 (2014).
4. Y. Chen, Y. Zhang, B. Chen, Z. Wang, C. Lu, J. Power Sources,
256, 20 (2014).
All Solid-State Lithium Cells Employing Hybrid Solid Electrolytes Containing Li+-Conducting Inorganic Electrolyte
Authors: Park Myungsoo , Jung Yun-Chae , Kim Dong-Won 
Published: February 2020

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices, electric vehicles and energy storage systems, due to their high energy density and long cycle life.1 However, safety issues still prevent full utilization of these batteries owing to the use of flammable liquid electrolytes, and thus safety problems have become a significant concern especially in large capacity applications such as electric vehicles and energy storage systems. In this respect, the development of all solid-state lithium batteries with non-flammable solid electrolytes may provide a fundamental solution to the safety issue of lithium batteries.2 As solid electrolytes, inorganic electrolytes have been actively studied for solid-state lithium battery applications. They usually exhibit relatively high ionic conductivity, wide electrochemical stability window and good chemical stability in contact with lithium metal. However, their hard and brittle mechanical properties do not allow easy construction of large-scale lithium batteries. In addition, lack of flexibility results in high interfacial resistance and poor interfacial contacts with electrode materials. Therefore, developing the flexible hybrid solid electrolyte with high ionic conductivity is an attractive and urgent work for all solid-state lithium batteries. In this study, the hybrid solid electrolytes composed of Li+-ion conducting inorganic electrolyte and polymer electrolyte were prepared in the form of flexible thin film, and their electrochemical properties were investigated. The hybrid solid electrolytes were applied to the all solid-state Li/LiNi0.6Co0.2Mn0.2O2cells, and their electrochemical performance was evaluated.

References

1. J.M. Tarascon and M. Armand, Nature, 414, 359 (2001).
2. E. Quartarone and P. Mustarelli, Chem. Soc. Rev., 40, 2525 (2011).
(Invited) Development of Transformational Technologies
Authors: Soloveichik Grigorii L. 
Published: February 2020

The Advanced Research Projects Agency (ARPA-E) funds high risk, high reward transformational research to reduce energy related emissions, reduce imports of energy from foreign sources, improve energy efficiency across all economic sectors, and ensure US technological lead in advanced energy technologies, including electrochemical energy storage and transformation for grid scale and automotive applications.
Storing energy in the form of liquid fuels has numerous advantages compared to conventional methods of energy storage (ES) such as batteries (high cost, short cycle life), pumped hydro and compressed air (low energy density). Low costs of storage and transportation of liquid fuels enables long-time ES and effective energy transportation using existing infrastructure technologies. Electrochemical synthesis of fuels allows for direct conversion of renewable electricity to chemical energy, which simplifies the process and increases the process efficiency. ARPA-E funds several projects targeting electrochemical synthesis of liquid fuels via OPEN and focused programs. The Reliable Electricity Based on Electrochemical Systems (REBELS) program aiming at distributed generation for more reliable and flexible smart grid focuses on intermediate temperature fuel cells that operate between 200-500oC and includes cell capable to produce liquid fuels along with electricity. The Renewable Electricity to Fuels through Utilization of Energy-dense Liquids (REFUEL) program seeks to fund the development of transformational technologies to reduce the barriers to widespread adoption of intermittent renewable energy sources by enabling the conversion of energy from these sources, water and air to energy-dense zero-carbon liquid fuels. This presentation will also highlight flow battery technologies using organic active materials including funded by ARPA-E. A comparison of organic and inorganic active materials in aqueous and non-aqueous electrolytes for flow battery applications will be presented. Compatibility of fuels, electrocatalysts and membranes will be discussed. State-of-the-art technologies for electrochemical synthesis of fuels and organic active materials using different types of electrochemical cells will be presented.
(Invited) Electrocatalysis of CO2 Reduction. from Fundamental Understanding to Catalyst Design and Preparation
Authors: Tian Na , Sheng Tian , Liu Li , Xie Ai-Yun , Zhang Feng-Yang , Hong Yu-Hao , Huang Long , Zhou Zhi-You , Sun Shi-Gang 
Published: February 2020

Electrocatalytic reduction of CO2 is of significance in environment for reducing greenhouse gas level, in carbon recycling and sustainable energy storage when CO2 is reduced into hydrocarbon fuels and other chemicals. The big challenge in electrocatalysis of CO2 reduction consists in the high energy barrier to activate the O=C=O band and the broad distribution of products. Therefore, the key issue is design and preparation of electrocatalysts with high catalytic activity and selectivity. In recent years, we have conducted investigations of electrocatalysis of CO2 reduction in the following three aspects:
(1) Using Pt single crystal planes (Pt(hkl)) as model catalysts to gain knowledge about the surface structure-catalytic functionality of CO2 reduction. In situ FTIR spectroscopy determined that the main CO2 reduction product on Pt(hkl) electrodes is CO, while the kinetics of the CO2 reduction depends on the surface atomic arrangements. It has revealed that the catalytic active centers for CO2 reduction consist of few atoms (5-6) of low coordination number (steps, kinks) in stereo structure;
(2) Investigation of electrocatalytic reduction of CO2 on a series Cu-based electrodes, including Cu tetrahexahedral nanocrystals bounded by {530} high-index facets prepared through electrochemically shape-controlled synthesis, polycrystalline Cu and oxide-derived Cu electrodes decorated with Zn, Ni and Au. The CO2 reduction products were determined by using mainly NMR. It has found that the decoration of Ni on oxide-derived Cu exhibited the highest catalytic activity for CO2 reduction, evidenced by significant increase in Faraday efficiency for yielding formic acid, ethanol, and n-propanol. At -1.5 V, the Faraday efficiency are respectively 30%, 1.6% and 2.7% for formic acid, ethanol and n-propanol on Ni decorated oxide-derived Cu, while the values are 8.3%, 1.2%, and 1.6% on Zn modified surface, 20.5%, 0.2%, and 0% on Au modified surface, and 20.9%, 0.8%, and 1.0% on the bare oxide-derived Cu surface. The promotion may mainly come from the stronger adsorption of intermediate CO* on Ni decorated surface than on Cu, which facilitates further the reduction of CO* with optimized hydrogen adsorption on Ni;
(3) DFT calculations of electrocatalytic reduction of CO2 through the development of methods for accurately modelling the electrochemical interface by using a liquid water/solid interface model with a number of explicit water molecules combining with ab initio molecular dynamics simulations. In this study, Cu(100) was used as model catalyst, the results revealed different intermediates and pathways involved in CO2 reduction and provided a detail description of the reaction mechanism and kinetics.

Acknowledgements: The study was supported by NSFC (21573183, 21229301, 21321062).
Key Parameters for the Design of Composites Electrodes for Water Splitting in Alkaline Medium
Authors: Arcidiacono Paul , Favier Frederic 
Published: February 2020

A study on the hydrogen evolution performances in alkaline medium (KOH 6M) of nickel-based composite electrodes has been carried out. Surface tension characteristics have been tuned by using various polymer binders of different hydrophobic/hydrophilic balances: polyvinyl alcohol (PVOH), polybenzimidazole (PBI), polyethylene oxide (PBI), polyvinidylene fluoride (PVDF), and Polytetrafluoroethylene (PTFE).
The composite electrodes fabricated by drop-casting exhibit various contact angles in an extended range from 43° to 115°. They were evaluated by steady-state polarization and electrochemical impedance spectroscopy (EIS) measurements. Electrochemical behavior and mechanism were discussed towards the electrode wettability through the evaluation of electrochemical parameters including the overpotential at 100 mA/cm², kinetic parameter b (mV/dec) and charge transfer resistance (Rct).
The bubble coverage, diameter before departure (lift off from the electrode surface) and residence time at the surface are greatly affected by the surface tension of the various electrodes. The comparison of the electrochemical performances revealed the importance of this characteristic for the design of an efficient hydrogen evolution electrode fabricated by a catalyst-binder approach.
From Ni-PVOH to Ni-PTFE electrodes with the same catalyst loading, the overpotential at 100 mA/cm² was improved by 150 mV. The kinetic tafel slope was kept close to 116 mV/dec (Volmer-Heyvroski step) for electrodes with a contact angle between 43° to 90 °, increased for contact angles above 90° to reach up to 178 mV/dec for PTFE-based electrode showing the greater contact angle in the series at 115°. Electrochemical impedance spectroscopy (EIS) measurements at various overpotentials show that the bubbles retained at the surface increase the electrode charge transfer resistance. This behavior is assigned to the hidden active sites and justifies the observed decrease in performances of hydrophobic electrodes.
This comprehensive study leads to a precise description of the interfacial phenomena at the microscopic scale during gas production by electrolysis and the evaluation of key parameters for the formulation of advanced electrodes.
Self-Supported Nickel Phosphide Nanoparticles with High Activity for Hyderogen Evolution Reacition
Authors: Jang Injoon , Park Hyun-Seo , Kim Jin Young , Jang Jong Hyun , Kim Hyoung-Juhn , Sung Yung-Eun , Yoo Sung Jong 
Published: February 2020

Hydrogen (H2) production have received considerable attention resulting from the urgent need of clean and renewable energy. Water splitting is a typical and eco-friendly strategy for H2 production method through efficient acidic electrolyzers with expensive platinum group metal catalysts (Pt). Therefore, researchers have developed alternative, cheap and robust catalysts made from earth-abundant elements. Very recently, nickel phosphides (NixPy) have been proven to be promising catalysts with high activity and durability in strong acidic media (0.5M or 1M H2SO4) for hydrogen evolution reaction (HER). The crystalline phase of NixPy is an important factor for determining the activity for HER (better HER activity as higher P contents in NixPy).
Herein, highly active and durable NixPy catalysts for HER are prepared using modified thermal decomposition method. In this process, nickel oxide (NiO) powder reduced to NixPy by phosphine gas (PH3) produced from sodium hypophosphite (NaH2PO2). Unlike conventional method, NiO is phosphidized from bi-located P source (NaH2PO2). One is placed upstream of furnace (traditional method) and the other is mechanically mixed with NiO powder. Based on X-ray diffraction analysis, synthesized NixPy catalysts had multi-phase crystalline structure (Ni2P, Ni5P4 and NiP2) and the NixPy with higher P content exhibited the smaller crystallite size. (Ni2P < 50 nm, Ni5P4 ~ 10 nm, NiP2 ~ 2nm). Consequently, Ni5P4 and NiP2 nanoparticles with higher HER activity are supported on micro-scaled Ni2P with better conductivity (self-supported NixPy nanoparticles), which result in improvement of electrochemical properties for HER. The NixPy catalysts showed exceptionally higher HER activity and durability in acidic media than single-phased Ni2P or Ni5P4 and this performance of the NixPy is comparable with that of Pt. Therefore, modified phosphidation method and self-supported NixPy catalyst provide new instruction for designing excellent HER catalysts.
(Invited) High-Temperature Electrosynthesis of Hydrogen and Chemicals
Authors: Minh Nguyen , de Miranda Paulo Emilio V. 
Published: February 2020

High-temperature electrochemical cells based on solid electrolytes have been considered for synthesis and production of hydrogen and a variety of other fuels and chemicals. Solid oxide electrolysis cells (SOECs), for example, are being developed for hydrogen production (from water), syngas production (from mixtures of water and carbon dioxide) and oxygen recovery (from water or carbon dioxide for space applications). The main attractive features of the SOEC are its simple chemistry, environmental compatibility and high electrical-to-hydrogen efficiency. Solid oxide fuel cell (SOFC) type cells have been investigated for production of chemicals and cogeneration of electricity and chemicals (in this case, the cell is referred to as CSOFC); examples include production of C2 hydrocarbons and syngas from methane. The key features of the CSOFC include its high selectivity and the possibility to produce valuable chemicals such as hydrocarbons using methane-rich gases from non-fossil origins. Current state-of-the-art SOECs and CSOFCs, both fundamentally derived from the more advanced conventional SOFC technology, are still in their feasibility/development stage. This paper discusses certain aspects in selected materials, performance and operation of the SOEC for hydrogen production from water and the CSOFC for production of C2 hydrocarbons from methane.
(Invited) Synthesis and Upgrading of Fuels Using Solid State Electrochemical Devices
Authors: Elangovan S , Hartvigsen Joseph J , Larsen Dennis , Hafen Tyler , Mosby James M , Elwell Jessica , Frost Lyman J 
Published: February 2020

High conversion efficiency and selectivity are the two primary attractive features of electrochemical processes, in particular those using high temperature ion selective membranes. By selectively removing specific ionic species, the radicals that are created will react to form new compounds. Oxygen ion conductors are commonly used to remove oxygen from oxidized species thus creating molecules with fuel value. Judicious selection of materials set and device operating conditions are required to achieve desired product formation. The electrocatalytic layers on the electrochemical cells perform two functions, that of a catalyst and as an electrical conductor. Appropriate choice of electrode materials is required for stable performance and to avoid unwanted product formation. Control of operating conditions, namely temperature, fraction converted, and driving potential also is critical to achieve the selectivity.
Ceramatec is currently developing electrochemical technologies using zirconia membrane based electrolysis devices for multiple applications. One is the production of fuels such as hydrogen from steam and syngas from a mixture of steam and carbon dioxide. The product can be used as gaseous fuel or further converted to liquid fuels using conventional chemical processes. The process enables highly efficient conversion and storage of intermittent wind and solar energy in the form of energy dense liquid fuels. The second application involves electrolysis of carbon dioxide of Mars atmosphere to produce CO and oxygen for fuel synthesis and life support for future manned mission. A third application is to develop deoxygenation technology to remove oxygen from liquid hydrocarbon compounds produced from biomass to increase its fuel properties.
The requirements of each of these applications are varied and necessitate different operating conditions and significant changes to conventional electrode materials developed for high temperature fuel cell applications. An overview of these technical challenges and approach to addressing them will be presented.
(Invited) Considerations of LED Efficiency for the Development of Phosphors for Solid State Lighting
Authors: Piquette Alan , Mishra Kailash C. , Bergbauer Werner , Galler Bastian 
Published: February 2020

The efficiencies as well as other spectral properties of near-UV, violet or blue light emitting diodes (LEDs) are too critical to be neglected when designing phosphors for white light emission in solid state lighting.
The efficiency, in particular, limits which phosphors are appropriate and which mechanisms should be explored further. In this talk, we will present efficiency data from state-of-the-art LEDs (Figure 1) and discuss their implications for phosphor design.
Given the spectral variations of LED efficiencies shown in Figure 1, we will consider limitations imposed on luminescence mechanisms such as absorption and emission processes, Stokes shift, and radiative lifetime, and high flux operations. Specifically, we will compare f→f, f→d, and d→d absorption mechanisms and use arguments based on oscillator strength to demonstrate why phosphors that rely on f→f absorption may not be good options. Stokes losses are unavoidable for any phosphor, but need to be minimized for overall energy efficiency. At the same time, designing a blue phosphor for either near-UV or violet LEDs is rather too difficult because of the required small Stokes shift for a broadband phosphor. Even if an efficient blue phosphor could be found, its emission is re-absorbed by the green and red components leading to lower efficacies. Another important consideration is the flux level encountered by the phosphor layer in LEDs. For a 1 mm2 LED operating at 35 A/cm2, the irradiance for a chip-level-converter is on the order of 0.5 W/mm2 (assuming a 1 W chip with 50% energy efficiency). This is significantly higher than traditional fluorescent technology where the irradiance is ∼10−4 W/mm2 for a typical T8, 4 ft. lamp operating at 50 kHz.[1]At such high flux densities, a phosphor needs to have either a short radiative lifetime or it must be removed from the chip and used in a remote configuration in order to avoid ground state depletion. With laser-activated phosphors becoming more popular, these lifetime considerations will become even more crucial.
We will also discuss the need for narrowband red phosphors and briefly evaluate the known options such as f→f transitions from trivalent lanthanides, d→d transitions from Mn4+ or Cr3+, and relatively narrow band emission due to d→f transitions from Eu2+in some nitride hosts, and, of course, quantum dots.
Finally, simulations comparing the spectral efficiencies and color rendering quality of both near-UV and blue pumped white light sources will be presented. Optimal choices for spectral properties of phosphors as well as LEDs will be discussed.
[1] A. Piquette, W. Bergbauer, B. Galler, and K. C. Mishra, ECS J. Solid State Sci. Technol., 5, R3146 (2016).

Figure 1