Effect Of Membrane Thickness Research Articles

Effect of Membrane Thickness and Operating Conditions on PEMFC Limiting Current Analysis

Hydrogen powered proton exchange membrane fuel cells (PEMFC) have great potentials to replace the traditional internal combustion engines due to its inherent advantages of zero greenhouse gas emissions, better fuel efficiency, quick startup, silent operation, less required maintenance, etc. In a PEMFC, oxygen transport is a critical performance limiting factor because of the sluggish oxygen reduction reaction kinetics. Limiting current method is a well-established in-situ diagnostic tool to measure the oxygen transport resistance in a PEMFC. To obtain accurate oxygen transport resistances, a few key assumptions need to be made including: (1) the effect of temperature gradient in the diffusion media is negligible, (2) no convective flow in the porous media, (3) oxygen is diluted in a gas mixture of nitrogen and water vapor, (4) the total oxygen transport resistance combines gas diffusion layer, microporous layer, and catalyst layer, (5) the effect of membrane thickness has negligible effect, and (6) the anode side does not affect the measurement results due to fast hydrogen oxidation reaction. In this study, we perform a systematic study of the effect of membrane thickness and operating conditions on obtaining robust and reliable limiting current measurement. Standard Nafion membranes of three different thicknesses (25, 50, and 85 µm) are tested with Toray 060 and Freudenberg H23C8 diffusion media. In addition, we further study the interaction between membrane thickness and asymmetric pressure and relative humidity and their effects on limiting current results. Our results show that membrane thickness and relative humidity are critical factors in obtaining reliable oxygen transport resistance due to their effect on overall water balance in the cell. Lastly, the experimental data are compared with the simulation results to establish fundamental understanding. Detailed experimental and analytical results will be presented at the conference.

Mathematical modeling of an integrated photovoltaic-assisted PEM water electrolyzer system for hydrogen production

This work provides a new mathematical model of photovoltaic (PV) solar panels integrated with proton exchange membrane (PEM) water electrolyzer cells for optimal hydrogen production. The proposed mathematical model evaluates the operating temperature of the PV solar panel and PEM water electrolyzer and the effect of membrane thickness on hydrogen production performance. In the model results, when the operating temperature of the PEM water electrolyzer increased from 25 °C to 80 °C, the hydrogen flow rate of about 1.44 and 1.82 mL/min at 2 A/cm2, respectively. Moreover, the maximum flow rate of hydrogen produced in a 7-cell and 14-cell PV-assisted PEM water electrolyzer stack is around 349.98 mL/min and 699.91 mL/min, respectively. The total efficiency of the integrated PV-assisted PEM water electrolyzer stack is around 6.0–6.5%, depending on the solar irradiance values. This mathematical model significantly contributes to green hydrogen production using the integrated PV-assisted PEM water electrolyzer system. Moreover, the mathematical model of PV-assisted PEM water electrolyzer will be a pioneer in determining the hydrogen production potential of the PEM water electrolyzer systems.

Effect of Membrane Thickness on Ion Transport in pH-Regulated Zero-Depth Interfacial Nanopores.

Zero-depth interfacial nanopores, which are formed by two crossed nanoscale channels at their intersection interface, have been proposed to increase the spatial resolution of solid-state nanopores. However, research on zero-depth interfacial nanopores is still in its early stages. Although it has been shown that the current passing through an interfacial nanopore is largely independent of the membrane thickness, existing studies have not fully considered the impact of membrane thickness on other ion transport characteristics within these nanopores. In this paper, we investigate the electrokinetic ion transport phenomenon in the zero-depth interfacial nanopores, especially focusing on the influence of membrane thickness on the ion transport phenomenon. Our model incorporates the Poisson-Nernst-Planck equations and the Navier-Stokes equations, featuring a pH-regulated surface charge density. We find that when the thickness of the nanochannels is close to the interface size of the formed interfacial nanopore, the phenomenon of ion transport in the interfacial nanopore is similar to that in a conventional cylindrical nanopore. However, when the thickness of the nanochannels is much greater than the interface size of the formed interfacial nanopore, several distinct phenomena occur. The surface charge density on the inner walls of the interfacial nanopores has a small peak at the interface of the two crossing nanochannels, and the anion concentration changes greatly between the two nanochannels; that is, a much greater anion concentration forms in the nanochannel near the anode side than in the nanochannel near the cathode side. When the surface charge is nonzero, the electric field within the interfacial nanopore creates three extreme points, and the directions of the local electric fields are opposite at the ends of the membrane.

Investigating the mechanism of Au(III) transport using a polymer inclusion membrane with dibutyl carbitol as a carrier

In this article, firstly, the separation and transfer of Au(III) from gold chloride solution was investigated using a polymer inclusion membrane (PIM) system containing dibutyl carbitol (DBC) as carrier molecules, dioctyl phthalate (DOP), bis(2-ethyl hexyl) adipate (dioctyl adipate) (DOA) and tris (2-ethyl hexyl) phosphate (T2EHP) as plasticizers and high molecular weight polyvinyl chloride (PVC) as the base polymer. Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM) were used to identify PIMs. Kinetic studies featuring a two-step reaction, with the first step being reversible, were conducted across various sections to investigate the processes of extraction, stripping, and transport. The effects of different stripping agents such as water, HCl, thiourea, sodium thiosulfate, and oxalic acid was investigated, and the best results were obtained with thiourea. Also, the mechanisms of Au(III) extraction and transport were studied. Under the conditions of source solution, tetrachloroaurate anionic complex AuCl4− with protonated DBC (ROR2OHM+) was extracted by ion solvation mechanism. The validity of the proposed extraction mechanism was confirmed through the use of nuclear magnetic resonance (1H NMR) spectroscopy. In order to make the membrane with the best composition and the highest efficiency, the effect of weight percentage of the carrier and plasticizer was investigated. There was an optimal value for the weight percentage of plasticizer (10–20% by weight) and carrier (40%), in which the highest flux and permeability in the membrane occurred. The effect of the viscosity of different plasticizers (DOP, DOA, and T2EHP) on the Au(III) flux was also investigated. It was found that the flux increases linearly with the reduction of plasticizer viscosity. Effect of membrane thickness on the permeability, initial flux, and efficiency of Au(III) transfer, were conducted with thickness of 120, 80, 45, and 30 μm. By reducing the thickness of the membrane, the transfer flux, permeability and percent of Au(III) transport, were improved from 12.9 × 10−3mh−1, 45.3 × 10−7molm−2s−1 and 18.2% to 26.4 × 10−3mh−1, 83.5 × 10−7molm−2s−1 and 37.3%, respectively. According to the results, a membrane with a combination of PVC:DBC:D2EHP with a weight percentage ratio of 50:40:10 with a thickness of 30 μm was suggested. Optimized results with the proposed membrane were obtained to be: extraction rate constant of 1.43 h−1, extraction percent of 99.1%, stripping rate constant of 37.5 × 10−4h−1, stripping percent of 40.9%, and permeability of 27.0 × 10−3mh−1, initial flux of 82.1 × 10−7molm−2s−1.

Biocarbon-Enhanced Flexible Nanofiber Mats for Sustainable Energy Generation and Wearable Device Applications

A broad diversity of nanofillers and polymers have been used to prepare polymer nanocomposites having potential applications in transportation, sports materials, aerospace, electronics, communication, energy, environment, and biomedical. Polyvinylidene fluoride (PVDF) finds a remarkable place in energy applications attributed to its highest known piezo- and pyroelectric properties. Like most carbon materials, Biochar has excellent electrical conductivity, since it comprises graphene layers with a great amount of carbon content. This study explores the behavior of composite nanofibers fabricated from rice straw-derived biochar-PVDF as wearable mats to harvest body energy into electricity. The composite nanofiber mats were fabricated using the electrospinning technique to get the benefit of both the piezoelectric properties of PVDF and the excellent electric properties of Biochar. The research found that incorporating 12 wt % of Biochar greatly enhances the piezoelectric content of the nanofiber mats without noteworthy loss in flexibility. In addition, the effects of membrane thickness (0.5, 0.9, and 1 mm) on their output voltages as a performance factor of the nanogenerator were measured. Results indicated that the effect of thickness was most influential in the thickness of 1 mm of PVDF/biochar nanofibers generator. The results of this work imply promising application development of such flexible composite piezoelectric nanofibrous membranes for environmentally sustainable energy generation and wearable self-powered electrical devices.

The effect of membrane thickness on the exergetic performance in PEMFC

The effect of membrane thickness on the exergetic performance in PEMFC

Temperature Dependency of Net Water Drag Coefficient in Polymer Electrolyte Fuel Cells

Because polymer electrolyte fuel cell (PEFC) systems for vehicles are stand-alone systems, the net water drag coefficient () is an essential index in water management and must be negative even during high temperature operation above 100 °C. In this study, to verify the water balance in the cell during high temperature operation, the effect of operating temperature on the current density () - characteristics under gas supply conditions similar to those of a real system was examined experimentally, where the water amount supplied to and discharged from the cell was measured at a cell temperature (T cell) of 80, 100, and 120 °C. The experimental results obtained here indicates that the gas supply conditions to keep negative becomes more limited as T cell is increased. This indicates that the relative humidity of supplied hydrogen should be kept low and that the stoichiometric ratio of hydrogen should be kept high. Furthermore, the effect of membrane thickness () on became more pronounced when T cell exceeded 100 °C, indicating that operation at 120 °C is not realistic for PEFCs that use a 30-μm-thick proton exchange membrane.

Effects of Membrane Thickness, Gas Pressure and Electron Dose in Gas Cell Transmission Electron Microscopy.

Effects of Membrane Thickness, Gas Pressure and Electron Dose in Gas Cell Transmission Electron Microscopy.

Effect of Membrane Thickness on Parameters for Producing High-Purity Hydrogen from Hydrocarbon Raw Materials in Membrane-Catalytic Devices

Effect of Membrane Thickness on Parameters for Producing High-Purity Hydrogen from Hydrocarbon Raw Materials in Membrane-Catalytic Devices

Membrane thickness affects ELIC activity & M4 helix structure.

Pentameric ligand gated ion channels (pLGICs) are a superfamily of ion channels involved in fast neural transmission. Some examples include the GABA(A) receptor and nicotinic acetylcholine receptor (nAchR). In the nAchR, it has been shown that thick membranes promote coupling of agonist binding to channel activation. However, the effect of membrane thickness on the ion transport activity of any pLGIC is not known. To investigate this, we reconstituted the model pLGIC, Erwinia ligand gated ion channel (ELIC), in liposomes consisting of di-monounsaturated phosphatidylcholine (PC) of varying acyl chain length (16-22), and assayed ion flux using a sequential mixing fluorescence quenching assay. ELIC exhibited maximal agonist responses in di-20:1PC liposomes with a dramatic decrease in thinner or thicker membranes. To verify that differences in agonist responses are not a function of changes in channel orientation in the liposomes, we further assayed an ELIC construct with a quenchable fluorescent label in the N-terminal ECD. Minimal differences in the amount of outwardly facing channels were observed in different membrane conditions confirming that changes in agonist responses are primarily a function of channel activity. To investigate the structural basis of ELIC sensitivity to membrane thickness, we obtained apo and agonist-bound structures of ELIC in a circularized nanodisc with di16:1PC, di20:1PC or di22:1PC using single particle cryo-EM. In the agonist-bound structures, the membrane facing helix, M4, is poorly resolved in thin (di16:1PC) and thick (di22:1PC) membranes but clearly resolved in di20:1PC, indicating a correlation between the structure and dynamics of M4 and the optimal membrane thickness that supports channel function. These findings indicate that ELIC function is promoted by thicker membranes and suggests that sensing of membrane thickness is mediated by M4, as has been proposed for the nAchR.

The effect of membrane thickness on the membrane permeabilizing activity of the cyclic lipopeptide tolaasin II.

Tolaasin II is an amphiphilic, membrane-active, cyclic lipopeptide produced by Pseudomonas tolaasii and is responsible for brown blotch disease in mushroom. To better understand the mode of action and membrane selectivity of tolaasin II and related lipopeptides, its permeabilizing effect on liposomes of different membrane thickness was characterized. An equi-activity analysis served to distinguish between the effects of membrane partitioning and the intrinsic activity of the membrane-bound peptide. It was found that thicker membranes require higher local peptide concentrations to become leaky. More specifically, the mole ratio of membrane-bound peptide per lipid needed to induce 50% leakage of calcein within 1 h, Re 50, increased monotonically with membrane thickness from 0.0016 for the 14:1 to 0.0070 for the 20:1 lipid-chains. Moreover, fast but limited leakage kinetics in the low-lipid regime were observed implying a mode of action based on membrane asymmetry stress in this time and concentration window. While the assembly of the peptide to oligomeric pores of defined length along the bilayer z-axis can in principle explain inhibition by increasing membrane thickness, it cannot account for the observed limited leakage. Therefore, reduced intrinsic membrane-permeabilizing activity with increasing membrane thickness is attributed here to the increased mechanical strength and order of thicker membranes.

A novel concept for pure hydrogen production and a massive reduction in CO2 emissions from the formaldehyde absorption process

AbstractThe Formox process is a well‐known process for formalin generation, which uses iron‐molybdenum oxide as a catalyst. Typically, the off‐gas from the formaldehyde absorption column in Formox process is burnt in the emission control system (ECS), resulting to produce a huge amount of CO2. This work proposes a modified process to remove formaldehyde and volatile organic compounds from the stack of formaldehyde absorbing tower. Steam reforming reactions in a novel fixed‐bed tubular membrane reactor is used instead of combustion reactions in a conventional fixed‐bed reactor in ECS. The process was modeled to evaluate the role of membrane reactor for CO2 mitigation in Formox process. The collected data from a domestic formalin plant were used for modeling purposes. The model was validated against experimental measurements obtained from other works. A good consistency was observed. The improvement in CO2 emission mitigation, as well as H2 production, was achieved by applying the Pd‐Ag membrane reactor filled with copper‐based catalyst. The CO2 emission rate considerably changed from 6,700 to 575 kg/day. Furthermore, by using the proposed reactor, the emission of formaldehyde and methanol vapors throughout the ECS plant were eliminated. The essential parameters such as reactor pressure, temperature, and membrane thickness on reactor performance were evaluated. By increasing the feed temperature, the carbon dioxide production rate decreases, and pure hydrogen production rate increases. The higher CO2 generation was observed at elevated pressures. The effect of membrane thickness on CO2 emission was negligible.

Sustainable nanofiltration membranes based on biosourced fully recyclable polyesters and green solvents

Herein, we report a new class of biosourced nanofiltration membranes based on chemically recyclable aliphatic polyesters (P(4,5-T6GBL)) and the use of green solvents. Given their chemical recyclability and potential biodegradability, these polyester membranes were designed to have a sustainable lifecycle. The effect of membrane thickness and solvent/non-solvent diffusivity on membrane morphology and organic solvent nanofiltration were investigated. Long-term membrane stability was tested in a continuous crow-flow filtration rig over a week, which exhibited stable methanol permeance at 8.6 ± 0.1 L m−2 h−1 bar−1. The rejection profiles of the pharmaceuticals oleuropein (540 g mol−1) and roxithromycin (837 g mol−1) were also found to be stable at 87% and 100%, respectively.

Computational fluid dynamics simulation for dual‐phase membrane module for CO 2 capture: Effect of membrane thickness, temperature and CO 2 feed concentration

CO2 capture and natural gas purification are of paramount significance in power plant applications nowadays. Dual-phase membrane is an effective approach for the enhancement of CO2/CH4 separation efficiency. In this study, CO2/CH4 binary gas mixture separation was simulated by using hydroxide/ceramic dual-phase (HCDP) membranes incorporated in the industrial-scaled tubular membrane module. Computational fluid dynamics (CFD) was utilized as the approach to model the fluid flow within the membrane module. Utilizing the CFD modeling of membrane module, the effects of tubular membrane thickness, operating temperature and CO2 feed concentration on the separation performance of HCDP membrane had been investigated. The results showed that membrane thickness affected the effective surface area of the membrane and CO2 permeance. The greater the membrane thickness, the lower was the membrane separation efficiency. The highest CO2 recovery obtained was 90.12% at 1 mm tubular membrane thickness, with the membrane stage cut ratio of 0.1950. Operating temperature imposed a notable influence on the gas permeance as well. By increasing the operating temperature, CO2 permeances were improved and hence, the separation performance of HCDP membrane was enhanced simultaneously. As for the effect of CO2 feed concentration on the membrane performance, it was found that the overall membrane performance and separation efficiency were better when the CO2 feed concentration was low, due to the higher availability of the adsorption sites on the membrane surface. In conformity with the membrane technology as a cost-effective CO2 sequestration technique, the dual-phase membrane has demonstrated a remarkable potential to be adopted for industrial applications.

Electrochemical Hydrogen Compression and Its Optimization through Computational Modeling

Climate change resulting from the heavy use of fossil fuels poses a serious threat to our environment. It is critically important to find alternatives to combustion-based energy technologies and promote renewable energy production. Hydrogen is a leading candidate for the transportation sector as a carbon-free fuel with high energy density. Hydrogen can be produced in a carbon-neutral manner via water electrolysis and other means. However, the establishment of the hydrogen infrastructure still faces serious challenges such as storage. Due to its lightweight nature, hydrogen is very difficult to store either as a compressed gas or as a liquid. Typically, hydrogen is compressed using mechanical compressors which contain moving parts that require frequent maintenance adding to their cost and complexity. Electrochemical compression (ECC) is a promising alternative to mechanical compressors. ECC is an electrochemical device that uses a proton exchange membrane (PEM) to compress the gas. When a voltage is applied across the PEM, low-pressure hydrogen supplied to the anode is oxidized to generate protons and electrons. The electrons are driven through the external circuit by the power source, whereas the protons travel through the PEM towards the cathode. The protons and electrons recombine via the cathodic reduction to obtain hydrogen at elevated pressure. The currently available knowledge base regarding electrochemical compressors has mainly resulted from experimental studies and less attention has been paid to modeling. The current work presents a comprehensive three-dimensional model of a single cell ECC that incorporates the relevant electrochemical phenomena as well as physical processes including water transport. It also takes into account the important phenomenon of back diffusion due to the pressure difference between the cathode and anode that limits the achievable pressure in the cathode compartment. Simulations were conducted for the pressurized cathode case . It was observed that back diffusion limits the compression ratio to a value well below that predicted by Nernst equation. Additionally, the effects of membrane thickness, temperature, and applied voltage on ECC performance are analyzed. The results show that there is a tradeoff between different objectives that must be addressed to optimize the ECC process. For example, thinner membranes permit faster compression rates but at the cost of increased back diffusion. Similarly, higher temperatures improve the pressure efficiency and the compression rate but at a higher operational cost. The results also show that ECC is more efficient at lower voltages because the associated compression ratio is smaller which consequently reduces back diffusion; however, such small voltages do not allow higher pressures. As a result of these tradeoffs, all design parameters need to be optimized simultaneously. This study offers valuable insights on the effect of different parameters on ECC performance. The results suggest that ECC is a viable alternative to conventional technologies for hydrogen compression. Back diffusion significantly reduces ECC efficiency; therefore, ECCs would benefit from membranes with low hydrogen diffusivity. The results provide a foundation for the modeling, analysis, and optimization of a full scale ECC system. Keywords—Hydrogen; Computational Model; Back Diffusion; Electrochemical Compression; Optimization;

Starch‐Based Membranes for Controlled Release of 5‐Fluorouracil In Vitro

AbstractStarch is a natural polymer that is among the sustainable materials and has the characteristics of being a green material in harmony with nature. In this study, a potential transdermal release system was evaluated by investigating 5‐fluorouracil (5‐FU) transfer through starch/poly(vinyl alcohol) (PVA) membranes in vitro. The effects of membrane thickness, starch/PVA blending ratio, pH, and temperature on the release of 5‐FU from the membranes were studied. At the end of the study, it was deduced that decrease in pH reduces the released amount of 5‐FU from starch/PVA membranes and 5‐FU transfer from membranes could be controlled within a fairly constant range. The diffusion coefficient was determined as 4.84 10−3, 4.49 10−3 and 2.54 10−3 cm2 s−1 for the pH of 7.4, 5.5, and 3.5, respectively. The activation energy for the permeation 5‐FU from starch/PVA membrane (60/40, v/v) was found to be 9.72 kJ mol−1.

Preparation and characterization of novel Polyamide-6/Chitosan blend dense membranes for desalination of brackish water

In this study, polyamide-6/chitosan blend dense membranes were prepared using solution casting technique. The membranes were then characterized by FTIR spectroscopy, TGA, SEM analysis and tensile testing. FTIR analysis confirmed hydrogen bonding between chitosan and polyamide. TGA analysis proved that all the membranes maintained thermal stability up to 370 °C. SEM analysis exhibited compact and dense structure of the membranes. The tensile properties of the membranes improved with the addition of hydrophilic chitosan. The membranes were then characterized for desalination properties using 2000 ppm NaCl solution by state-of-the-art dead-end membrane desalination equipment at 20 bar operating pressure. The effect of membrane thickness was then studied, and the best thickness of the membrane was determined for optimum water flux and salt rejection. The effect of chitosan concentration was also studied, and the best concentration was determined for optimum desalination properties. It has been found that the membrane having 200 micron thickness and 3 wt.% chitosan demonstrated optimum desalination properties that is 75% salt rejection and water flux of 1.52 kg/h.m2. It has been found that maximum salt rejection was achieved with 2 wt.% chitosan blend membrane and maximum permeate flux was achieved with 4 wt.% chitosan blend membrane.

Selective Extraction of Gold with Polymeric Inclusion Membranes Based on Salen Ligands with Electron- Accepting Substituents

Salen-type ligands with electron-accepting substituents on the aromatic ring were synthesized. These ligands were used as extractant agents in polymeric inclusion membranes for the extraction of metal ions from aqueous solutions. Measurements of the membrane potential indicated selectivity of the membrane, which was confirmed by the quantification of the extracted metal. Ten types of metal ions were studied to establish the selectivity of each membrane. Salen-type ligands had higher selectivity to gold than to other metals and allowed for the extraction of acceptable percentages of this metal. The results showed that the percentage of extracted gold depends on the type of substituent present in the ligand`s aromatic ring, the pH of the working solution and the area of the membrane. There was no effect of membrane thickness on the metal extracted. The time required to reach a certain extraction percentage decreased considerably as the membrane area increased.

Optimization of the Catalytic Layer for Alkaline Fuel Cells Based on Fumatech Membranes and Ionomer

Polymer electrolyte fuel cells with alkaline anion exchange membranes (AAEMs) have gained increasing attention because of the faster reaction kinetics associated with the alkaline environment compared to acidic media. While the development of anion exchange polymer membranes is increasing, the catalytic layer structure and composition of electrodes is of paramount importance to maximize fuel cell performance. In this work, we examine the preparation procedures for electrodes by catalyst-coated substrate to be used with a well-known commercial AAEM, Fumasep® FAA-3, and a commercial ionomer of the same nature (Fumion), both from Fumatech GmbH. The anion exchange procedure, the ionomer concentration in the catalytic layer and also the effect of membrane thickness, are investigated as they are very relevant parameters conditioning the cell behavior. The best power density was achieved upon ion exchange of the ionomer by submerging the electrodes in KCl (isopropyl alcohol/water solution) for at least one hour, two exchange steps, followed by treatment in KOH for 30 min. The optimum ionomer (Fumion) concentration was found to be close to 50 wt%, with a relatively narrow interval of functioning ionomer percentages. These results provide a practical guide for electrode preparation in AAEM-based fuel cell research.

Performance assessment of gas crossover phenomenon and water transport mechanism in high pressure PEM electrolyzer

To improve proton exchange membrane (PEM) electrolyzes’ performance the voltage loss through them should be avoided. In this work, it is intended to analyze losses including of diffusion loss, ohmic loss due to electrode, bipolar plate (BP), and membrane resistances, and gas crossover associated with the water transferring mechanisms. All of the losses are associated with water transferring mechanisms, which is created due to electro-osmoic drag, pressure differential between the anode and cathode sides, and diffusion. Furthermore, the effect of membrane thickness, cathode pressure, and operating temperature on the hydrogen crossover is examined. In addition, the contribution of ohmic loss due to electrode bipolar plate (BP), and membrane resistances is studied and, the contribution of different losses on the cell performance is discussed. Results show that raising cathode pressure from 1 to 40 bar lead to the increment of anodic hydrogen content from 1.038% to 21% at the specific current density of 10,000 A/m2. Enhancing the thickness of membrane has considerable impact on decrementing anodic hydrogen content, but the mass transfer loss rises from 0.022 to 0.027 V with enhancing membrane thickness from 50 to 300 μm, respectively. Furthermore, the contribution of voltage losses, assigned to each of losses are equal to 85%, 3%, and 12% for activation, diffusion and ohmic losses, respectively. It is found that, from the reported contribution for ohmic loss, the contribution of electrode BP, and membrane resistances are 31% and 69%, respectively.