scholarly journals Pressure Sensitivity Enhancement of Porous Carbon Electrode and Its Application in Self-Powered Mechanical Sensors

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 58 ◽  
Author(s):  
Keren Dai ◽  
Xiaofeng Wang ◽  
Zheng You ◽  
He Zhang
Keyword(s):  
Porous Electrode ◽  
Porous Electrodes ◽  
Mechanical Effects ◽  
Porous Carbon Electrode ◽  
Limited Power ◽  
Elastic Rubber ◽  
Self Powered ◽  
Rubber Component ◽  
Mechanical Sensors ◽  
Material Preparation

Microsystems with limited power supplies, such as electronic skin and smart fuzes, have a strong demand for self-powered pressure and impact sensors. In recent years, new self-powered mechanical sensors based on the piezoresistive characteristics of porous electrodes have been rapidly developed, and have unique advantages compared to conventional piezoelectric sensors. In this paper, in order to optimize the mechanical sensitivity of porous electrodes, a material preparation process that can enhance the piezoresistive characteristics is proposed. A flexible porous electrode with superior piezoresistive characteristics and elasticity was prepared by modifying the microstructure of the porous electrode material and adding an elastic rubber component. Furthermore, based on the porous electrode, a self-powered pressure sensor and an impact sensor were fabricated. Through experimental results, the response signals of the sensors present a voltage peak under such mechanical effects and the sensitive signal has less clutter, making it easy to identify the features of the mechanical effects.

scholarly journals Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

2019 ◽  
Vol 26 (5) ◽  
pp. 1600-1611 ◽  
Author(s):  
Gihan Kwon ◽  
Yeong-Ho Cho ◽  
Ki-Bum Kim ◽  
Jonathan D. Emery ◽  
In Soo Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrochemical Cell ◽  
Porous Electrode ◽  
High Energy ◽  
Porous Electrodes ◽  
X Ray ◽  
Pdf Analysis ◽  
Thin Film Catalysts

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

scholarly journals MAS-NMR of [Pyr13][Tf2N] and [Pyr16][Tf2N] Ionic Liquids Confined to Carbon Black: Insights and Pitfalls

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6690
Author(s):  
Steffen Merz ◽  
Jie Wang ◽  
Petrik Galvosas ◽  
Josef Granwehr
Keyword(s):  
Ionic Liquids ◽  
Carbon Black ◽  
Porous Electrode ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Porous Electrodes ◽  
Aggregation Behavior ◽  
Magic Angle ◽  
Additional Parameter ◽  
Inversion Algorithm

Electrolytes based on ionic liquids (IL) are promising candidates to replace traditional liquid electrolytes in electrochemical systems, particularly in combination with carbon-based porous electrodes. Insight into the dynamics of such systems is imperative for tailoring electrochemical performance. In this work, 1-Methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-Hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide were studied in a carbon black (CB) host using spectrally resolved Carr-Purcell-Meiboom-Gill (CPMG) and 13-interval Pulsed Field Gradient Stimulated Echo (PFGSTE) Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). Data were processed using a sensitivity weighted Laplace inversion algorithm without non-negativity constraint. Previously found relations between the alkyl length and the aggregation behavior of pyrrolidinium-based cations were confirmed and characterized in more detail. For the IL in CB, a different aggregation behavior was found compared to the neat IL, adding the surface of a porous electrode as an additional parameter for the optimization of IL-based electrolytes. Finally, the suitability of MAS was assessed and critically discussed for investigations of this class of samples.

Co-electrolysis of H2O and CO2in a solid oxide electrolysis cell with hierarchically structured porous electrodes

2015 ◽  
Vol 3 (31) ◽  
pp. 15913-15919 ◽  
Author(s):  
Chenghao Yang ◽  
Jiao Li ◽  
James Newkirk ◽  
Valerie Baish ◽  
Renzong Hu ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Porous Electrode ◽  
Tape Casting ◽  
Porous Electrodes ◽  
Solid Oxide ◽  
Electrochemical Reactions ◽  
Electrolysis Cell ◽  
Straight Channel ◽  
Solid Oxide Electrolysis ◽  
Solid Oxide Electrolysis Cell

A solid oxide electrolysis cell with novel asymmetric-porous structured electrodes has been fabricated by freeze-drying tape-casting and impregnation methods. The straight channel-like pores in the porous electrode facilitate mass transport while the nano- or sub-micron-sized catalysts promote the electrode electrochemical reactions.

Numerical Simulation of SOFC Performance Affected by Cathode Mesoscale-Structure Control

2008 ◽  
Author(s):  
Akio Konno ◽  
Hiroshi Iwai ◽  
Motohiro Saito ◽  
Hideo Yoshida
Keyword(s):  
Numerical Simulation ◽  
Current Density ◽  
Porous Electrode ◽  
Gas Diffusion ◽  
Porous Electrodes ◽  
Cell Performance ◽  
Structure Control ◽  
Mesoscale Structures ◽  
Mesoscale Structure ◽  
Electrolyte Interface

Increase of the current density is one of the most important topics in the development of solid oxide fuel cells. In this study we focus on the possibility of the current density enhancement by controlling the mesoscale structure of the electrodes. Modifications of the mesoscale structures increase the area of electrode-electrolyte interface and the volume of the electrode, reduce the electrolyte thickness, affect gas diffusion in the porous electrode and consequently influence the cell performance. To evaluate its effect on the cell performance, two-dimensional numerical simulation for SOFC with and without mesoscale grooves on the cathode-electrolyte interface is conducted to understand the effects of such cathode mesoscale structure on the cell performance. It is found that the electrochemical reaction in porous electrodes takes place in the region close to the electrode-electrolyte interface and the cell performance can be improved by applying cathode mesoscale structures.

Generalized staircase model of electrochemical impedance of pores in supercapacitor electrodes

2021 ◽  
pp. 30-51
Author(s):  
Сергей Николаевич Пронькин ◽  
Нина Юрьевна Шокина
Keyword(s):  
Experimental Data ◽  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Porous Electrode ◽  
Porous Electrodes ◽  
Energy Storage Devices ◽  
New Model ◽  
Storage Devices ◽  
Cylindrical Pores ◽  
Interfacial Impedance

Представлена новая обобщенная лестничная модель электрохимического импеданса для пористых материалов электродов в устройствах хранения энергии. Дано краткое описание существующих моделей межфазного импеданса и их ограничений. Новая модель основана на общепринятой “лестничной” модели импеданса цилиндрических пор. Однако новая модель учитывает сложную пористую структуру электродных материалов. В частности, модель описывает импеданс электродов с иерархической пористой разветвленной структурой, в которой широкие поры разветвляются в более узкие. Новая модель позволяет вычислить импеданс межфазной границы электрод/электролит в присутствии как нефарадеевских, так и фарадеевских процессов. Модель успешно опробована для пор с простой геометрией, для которых существуют точные решения. Изучено влияние структурных параметров модельных пористых электродов на их характеристики работы в суперконденсаторах. Проанализировано влияние диаметра пор, величины расширения начал пор и разветвления пор. Сформулированы критерии направленного дизайна электродных материалов для суперконденсаторов A new generalized staircase model of the electrochemical impedance is presented for porous electrode materials in energy storage devices. A brief overview on existing models of interfacial impedance and their limitations is given. The new model is based on the conventional staircase model of the impedance in cylindrical pores. However, the new model takes into account the complex porous structure of electrode materials. In particular, the impedance of hierarchical branching porous electrodes is described, i.e. the wide pores branching into the narrower pores. The new model allows to evaluate the impedance of the electrode/electrolyte interface in the presence of both non-faradaic and faradaic processes. The model is validated using the available exact solutions and experimental data for simple pore geometries. The influence of the parameters of structure of model porous electrodes on their performance in supercapacitors is studied. In particular, the influence of the diameter of the pores, width of pore openings, branching of pores is analyzed. The guideline for focused design of electrode materials of supercapacitors is outlined

scholarly journals A finite difference equivalent circuit approach to secondary current modelling in annular porous electrodes

2001 ◽  
Vol 5 (2) ◽  
pp. 119-132
Author(s):  
T. W. Farrell ◽  
D. L. S. Mcelwain ◽  
D. A. J. Swinkels
Keyword(s):  
Finite Difference ◽  
Equivalent Circuit ◽  
Porous Electrode ◽  
Porous Electrodes ◽  
Degree Of Polarization ◽  
Secondary Current ◽  
Current Distributions ◽  
Circuit Techniques ◽  
Model Equations ◽  
Current Modelling

An equivalent circuit for an annular porous electrode is derived by reinterpreting the differential equations that approximate the distribution of voltage and current in such electrodes. The equivalent circuit is shown to provide useful physical interpretations of the secondary current distributions. Multi-loop circuit techniques are employed to obtain the current distributions within the circuit. The solutions are shown to compare well with the exact solutions of the model equations. In addition, the equivalent circuit approach is used to investigate the effect of curvature on the degree of polarization of the electrode.

scholarly journals Infiltrated and Isostatic Laminated NCM and LTO Electrodes with Plastic Crystal Electrolyte Based on Succinonitrile for Lithium-Ion Solid State Batteries

Batteries ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 11
Author(s):  
Matthias Coeler ◽  
Vanessa van Laack ◽  
Frederieke Langer ◽  
Annegret Potthoff ◽  
Sören Höhn ◽  
...  
Keyword(s):  
Solid State ◽  
Polymer Electrolyte ◽  
Porous Electrode ◽  
Active Material ◽  
Tape Casting ◽  
Lithium Ion ◽  
Porous Electrodes ◽  
Plastic Crystal ◽  
Crystal Polymer ◽  
Solid State Batteries

We report a new process technique for electrode manufacturing for all solid-state batteries. Porous electrodes are manufactured by a tape casting process and subsequently infiltrated by a plastic crystal polymer electrolyte (PCPE). With a following isostatic lamination process, the PCPE was further integrated deeply into the porous electrode layer, forming a composite electrode. The PCPE comprises the plastic crystal succinonitrile (SN), lithium conductive salt LiTFSI and polyacrylonitrile (PAN) and exhibits suitable thermal, rheological (ƞ = 0.6 Pa s @ 80 °C 1 s−1) and electrochemical properties (σ > 10−4 S/cm @ 45 °C). We detected a lowered porosity of infiltrated and laminated electrodes through Hg porosimetry, showing a reduction from 25.6% to 2.6% (NCM infiltrated to laminated) and 32.9% to 4.0% (LTO infiltrated to laminated). Infiltration of PCPE into the electrodes was further verified by FESEM images and EDS mapping of sulfur content of the conductive salt. Cycling tests of full cells with NCM and LTO electrodes with PCPE separator at 45 °C showed up to 165 mAh/g at 0.03C over 20 cycles, which is about 97% of the total usable LTO capacity with a coulomb efficiency of between 98 and 99%. Cycling tests at 0.1C showed a capacity of ~128 mAh/g after 40 cycles. The C-rate of 0.2C showed a mean capacity of 127 mAh/g. In summary, we could manufacture full cells using a plastic crystal polymer electrolyte suitable for NCM and LTO active material, which is easily to be integrated into porous electrodes and which is being able to be used in future cell concepts like bipolar stacked cells.

Phase Change and Two Phase Flow in Cathode Porous Electrodes of Fuel Cells

2004 ◽  
Author(s):  
R. Bradean ◽  
K. Promislow ◽  
B. Wetton
Keyword(s):  
Fuel Cell ◽  
Phase Change ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Porous Electrode ◽  
Catalyst Layer ◽  
Proton Exchange ◽  
Porous Electrodes ◽  
Two Phase ◽  
Component Mixture

The steady state transport phenomena in the cathode porous electrode of a proton exchange membrane (PEM) fuel cell are investigated in a two-dimensional configuration near the outlet. The fuel cell is operated by hydrogen and humidified oxygen in a regime in which the porous cathode contains a two-phase two-component mixture of oxygen, water vapor and liquid water. Numerical results are presented for the liquid water, oxygen and temperature distributions through the cathode porous electrode. The phase change effect on the transport of reactant to the catalyst layer is found to be important.

Modeling of Microfluidic Fuel Cells With Flow-Through Porous Electrodes

2010 ◽  
Author(s):  
Ali Ebrahimi Khabbazi ◽  
Mina Hoorfar
Keyword(s):  
Fuel Cell ◽  
Solid Phase ◽  
Porous Electrode ◽  
Porous Electrodes ◽  
Metal Catalyst ◽  
Redox Species ◽  
Redox Couples ◽  
Flow Through ◽  
Microfluidic Fuel Cell ◽  
Vanadium Redox

This paper presents a modeling of a microfluidic fuel cell with flow-through porous electrodes using vanadium redox couples as the fuel and oxidant. There are advantages associated with the use of vanadium redox species in microfluidic fuel cell: 1) vanadium redox couples have the possibility of producing high open-circuit potential (up to 1.7 V at uniform PH [1]); 2) they have high solubility (up to 5.4 M) which causes more species available to the electrodes; 3) they do not require metal catalyst for electrochemical reactions so the reactions take place on the bare carbon electrodes. This characteristic of the vanadium redox couple make them a great candidate as reactants as they do not need expensive catalyst coatings on the electrodes. The fuel and the oxidant can be brought into contact with the electrode in two different ways: flowing over the electrodes or flowing through the electrodes. In the presented fuel cell design, the vanadium redox species are forced to flow through the porous electrodes. They finally come to meet each other in the middle microchannel and establish a side-by-side co-laminar flow traveling down the channel. In this paper, the effect of the inlet velocity and electrode porosity has been investigated. As it is expected, the higher velocity results in the higher power densities. For the porosity, however, there is an optimum value. In essence, there is a trade-off between the available electrode surface area and electric conductivity of the solid phase (i.e., the porous carbon electrode). The modeling shows that a porous electrode with a 67% porosity results in the highest power output.

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