Concentration Polarization Resistance Research Articles

Impact of Coating Layer Parameters on Electrode Tortuosity

The performance of Li-ion batteries is highly influenced by the microstructure of the assembled electrodes. Typically, porosity is chosen as a standard characteristic parameter, describing the morphology of the material components in the coated layer. However, transport phenomena and concentration polarization resistance also depend on the tortuosity of the electrode coating [1]. Therefore, it is crucial to determine the relationship between coating parameters (such as coating speed and drying parameters) and their effect on the tortuosity. Especially for thick electrodes an elongation of ionic transport pathways can arise due to the inhomogeneous distribution of the materials. Dead ends, branches, and surface impurities can lead to an increase in effective tortuosity [2], which can be minimized by careful selection of the coating parameters. A high binder concentration at the layer surface, caused by binder particles migrating during the drying process, can lead to a blockage of Li-channels [3, 4]. This can not only diminish the mechanical stability of the electrode but also harm the cycling performance, due to limitations in mass and charge transport [5].Electrochemical impedance spectroscopy can be used as a characterization technique to investigate the tortuosity of the electrode. Symmetric cells in combination with a non-intercalating electrolyte create a blocking condition of the cells. Extrapolating the spectrum's high and low-frequency regions, offsets in the real part of the impedance can be determined in the Nyquist plot (Figure 1a). The ionic resistance can be determined, and consequently, tortuosity can be calculated. A modified transmission line model can be used for in-depth analysis.In the case of homogenously distributed material, tortuosity should be an intrinsic value. In this work, a threshold value of the electrode thickness was determined, above which the tortuosity increases drastically (Figure 1b). This leads to the conclusion that when increasing the thickness, changes in the layer composition can arise.Additionally, the correlation between tortuosity and porosity was investigated and associated Bruggeman coefficients were compared.In a previous study, the multilayer coating technique has proven itself to be beneficial for increasing the electrochemical performance of high-loading electrodes containing cells [6]. Subsequent coating of multiple layers on top of each other enables the possibility to fine-tune material distributions along the layer thickness. Particularly, electrodes with an imposed binder gradient, of low concentration at the electrode separator interface, show a noteworthy decrease in tortuosity [7].This study was done on cathode samples with NMC811 as active material. Processing was done with both water and NMP, to show the impact of the solvent on the electrode tortuosities. Acknowledgments This work was financially supported by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology (bmk).[1] B. Tjaden, D. J. L. Brett, and P. R. Shearing, “Tortuosity in electrochemical devices: a review of calculation approaches,” International Materials Reviews, vol. 63, no. 2, pp. 47–67, Feb. 2018, doi: 10.1080/09506608.2016.1249995.[2] J. Landesfeind, J. Hattendorff, A. Ehrl, W. A. Wall, and H. A. Gasteiger, “Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy,” J Electrochem Soc, vol. 163, no. 7, pp. A1373–A1387, 2016, doi: 10.1149/2.1141607jes.[3] F. Font, B. Protas, G. Richardson, and J. M. Foster, “Binder migration during drying of lithium-ion battery electrodes: Modelling and comparison to experiment,” J Power Sources, vol. 393, no. December 2017, pp. 177–185, Jul. 2018, doi: 10.1016/j.jpowsour.2018.04.097.[4] S. Jaiser, M. Müller, M. Baunach, W. Bauer, P. Scharfer, and W. Schabel, “Investigation of film solidification and binder migration during drying of Li-Ion battery anodes,” J Power Sources, vol. 318, pp. 210–219, 2016, doi: 10.1016/j.jpowsour.2016.04.018.[5] M. Baunach, S. Jaiser, S. Schmelzle, H. Nirschl, P. Scharfer, and W. Schabel, “Delamination behavior of lithium-ion battery anodes: Influence of drying temperature during electrode processing,” Drying Technology, vol. 34, no. 4, pp. 462–473, 2016, doi: 10.1080/07373937.2015.1060497.[6] L. Neidhart, K. Fröhlich, N. Eshraghi, D. Cupid, F. Winter, and M. Jahn, “Aqueous Manufacturing of Defect-Free Thick Multi-Layer NMC811 Electrodes,” Nanomaterials, vol. 12, no. 3, pp. 1–15, 2022, doi: 10.3390/nano12030317.[7] L. Neidhart, K. Fröhlich, F. Winter, and M. Jahn, “Implementing Binder Gradients in Thick Water-Based NMC811 Cathodes via Multi-Layer Coating,” Batteries, vol. 9, no. 3, p. 171, Mar. 2023, doi: 10.3390/batteries9030171. Figure 1

Membrane fouling and influencing factors of a submerged commercial ceramic flat membrane bioreactor in treatment of coal chemical wastewater

An anoxic/oxic (A/O) treatment unit was upgraded using a submerged commercial ceramic flat-membrane bioreactor. The upgraded bioreactor effectively treated coal chemical wastewater. However, the factors influencing membrane fouling remain unclear. Thus, this study explored the mechanisms of membrane fouling of a commercial ceramic flat membrane bioreactor. With increasing duration of backwash, the rate of growth of transmembrane pressure (TMP) gradually increased. The proportions of concentration polarization resistance Rp and cake layer resistance Rf were 48.87% and 50.08%, respectively. Under the action of static electricity, negatively charged particles in the mixed liquid do not easily adhere to the membrane. Under conditions of high mixed liquid suspended solids (＞12 000 mg/L), an increase in the suspended solid content in the mixture caused membrane fouling and pore blockage. When the flux exceeded 58 L·m−2·h−1, the TMP increased sharply. When the aeration rate exceeded 200 mL/min, the impact of membrane erosion on fouling was no longer significant. The optimal suction/cessation ratio was 7:3. After cleaning with NaOH and NaClO, surface fouling of the membrane was significantly reduced.

Single-Ion Gel Polymer Electrolyte based on In-Situ UV Irradiation Cross-Linked Polyimide Complexed with PEO for Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) have become the research focus of energy storage products. Due to the combination of Li+ and the Lewis basic sites of polymer chains, anions move more than five times faster, which do not participate in the electrode reaction during the discharge cycles, leading to concentration polarization, voltage losses, and high internal resistance. To solve this phenomenon, in this work, a polymer network structure of single-ion polymer electrolyte-based polyimide (DPI-SIGPE) with plasticizer ethylene carbonate (EC)/dimethyl carbonate (DMC) is formed by in-situ cross-linking double bond polyimide, 4-styrene sulfonyl (benzenesulfonyl) imide, and cross-linking agent pentaerythritol tetra(2-thiol acetate) under UV irradiation. By incorporating the anion as a part of the polymer chain, DPI-SIGPE exhibits high lithium-ion conductivity of 2.7 × 10-4 S cm-1 at 30 °C and transference number of 0.87. Typical lithium stripping/plating cycling of 900h demonstrates uniform lithium deposition impacted by DPI-SIGPE. Meanwhile, it has good dimensional thermal stability with no obvious shrinkage at 200 °C for 0.5h and wide electrochemical window of 4.6V. Thus, the polyimide-based cross-linked single-ion gel polymer electrolyte has the promising potential for application in LIBs.

The mystery of Li<sub>2</sub>O<sub>2</sub> formation pathways in aprotic Li–O<sub>2</sub> batteries

The solid-state discharge product Li<sub>2</sub>O<sub>2</sub> is closely related to the performance of Li–O<sub>2</sub> batteries, which exacerbates the concentration polarization and charge transfer resistance, leading to sudden death and poor cyclability. Although previous theories of the Li<sub>2</sub>O<sub>2</sub> formation pathway help to guide battery design, it is still difficult to explain the full observed Li<sub>2</sub>O<sub>2</sub> behaviors, especially for those with unconventional morphologies. Thus, the pathways of Li<sub>2</sub>O<sub>2</sub> formation remain mysterious. Herein, the evolution of the understanding of Li<sub>2</sub>O<sub>2</sub> formation over the past decades is traced, including the variable Li<sub>2</sub>O<sub>2</sub> morphologies, the corresponding reaction pathways, and the reaction interfaces. This perspective proposes that some Li<sub>2</sub>O<sub>2</sub> particles are strongly dependent on the electrode surface as a result of the dynamic coupling of solution and surface pathways and emphasizes a possible mechanism based on previous experimental results and theories. Further methods are expected to be developed to reveal complex Li<sub>2</sub>O<sub>2</sub> formation pathways and spearhead advanced Li–O<sub>2</sub> batteries.

Identification of internal polarization dynamics for solid oxide fuel cells investigated by electrochemical impedance spectroscopy and distribution of relaxation times

Reliability and durability are two major problems restricting for Solid oxide fuel cells (SOFCs) industrial applications. To ensure the long-term stability, understood the internal operation mechanism of SOFC was necessary. The polarization curve combined with the distribution of relaxation times (DRT) method to analyze the electrochemical impedance spectroscopy (EIS) was used to identify the SOFCs modulation and degradation effect through the excitation frequency. Dynamic evolution of carbon deposition process and specific time constants were determined employing EIS and DRT. Special attention was paid to the dependency between the complex reaction processes that occur during the different operation of SOFC. The corresponding frequencies of concentration and activation polarization resistances in EIS were investigated under various gas compositions. The high concentration polarization resistance caused by the addition of nitrogen and hydrogen starvation was the key limiting factor for high cell power density. The total polarization resistance increased from 1.50 Ω/cm2 to 5.26 Ω/cm2 when the H2:N2 ratio decreased from 1:0 to 1:5. The anode did not deteriorate due to the poisoning of Ni particles in a short-term tested under 0.5 A/cm2 current density when the fuel was methane.

Impacts of Calcium Addition on Humic Acid Fouling and the Related Mechanism in Ultrafiltration Process for Water Treatment.

Humic acid (HA) is a major natural organic pollutant widely coexisting with calcium ions (Ca2+) in natural water and wastewater bodies, and the coagulation-ultrafiltration process is the most typical solution for surface water treatment. However, little is known about the influences of Ca2+ on HA fouling in the ultrafiltration process. This study explored the roles of Ca2+ addition in HA fouling and the potential of Ca2+ addition for fouling mitigation in the coagulation-ultrafiltration process. It was found that the filtration flux of HA solution rose when Ca2+ concentration increased from 0 to 5.0 mM, corresponding to the reduction of the hydraulic filtration resistance. However, the proportion and contribution of each resistance component in the total hydraulic filtration resistance have different variation trends with Ca2+ concentration. An increase in Ca2+ addition (0 to 5.0 mM) weakened the role of internal blocking resistance (9.02% to 4.81%) and concentration polarization resistance (50.73% to 32.17%) in the total hydraulic resistance but enhanced membrane surface deposit resistance (33.93% to 44.32%). A series of characterizations and thermodynamic analyses consistently suggest that the enlarged particle size caused by the Ca2+ bridging effect was the main reason for the decreased filtration resistance of the HA solution. This work revealed the impacts of Ca2+ on HA fouling and demonstrated the feasibility to mitigate fouling by adding Ca2+ in the ultrafiltration process to treat HA pollutants.

Self-Adaptive 3D Skeleton with Charge Dissipation Capability for Practical Li Metal Pouch Cells

Increased concentration polarization and cell resistance due to aggregation of “dead Li” is one of the main factors that cause capacity decay during cycling of practical lithium metal batteries. Effective strategies that are able to accommodate dynamic volume expansion of “dead Li” is required to solve the above problem. Herein, a compressible 3D skeleton (polyaniline modified melamine foam) is introduced to modify lithium metal anode to self-adapt the volume expansion. Meanwhile, moderate conductivity of this 3D skeleton can induce the “bottom-up” deposition manner of Li and provide electron pathways to exploit the inactive Li in “dead Li”. More importantly, the COMSOL simulations show that the 3D skeleton can effectively dissipate electrons accumulated on the tips of dendritic Li when unwanted Li dendrites contact the 3D skeleton to achieve low local current density. As a result, a Li/Cu cells using this 3D skeleton on the Cu side show long-term stability within 100 cycles under 3.8 mAh/cm2, and Li symmetrical cells using 3D skeleton modified Li foils achieve stable cycling for 2750 h under 5.0 mAh/cm2. The feasible fabrication process enables us to fabricate 0.6 Ah 3D skeleton modified Li/NCM811 pouch cells, which deliver capacity retention of 85% after 80 cycles under practical test protocols.

Polystyrene microsphere assisted synthesis of a Co/PEG comodified PbO2 anode and its electrocatalytic oxidation performance

• The Co-PEG-PbO 2 electrode was prepared by PS-assisted electrodeposition. • The electrode possess porous structure and high electrocatalytic performance. • The degradation of p-chlorophenol follows the CE mechanism. Highly performed electrode is one of the key factors affecting the efficiency of oxidation toward organic pollutants. To improve the electrocatalytic performance and stability of PbO 2 electrode, a Co-PEG-PbO 2 electrode modified by Co 2+ ion and polyethylene glycol (PEG 6000) was prepared by polystyrene microspheres assisted electrodeposition combined with surface structure adjustment and active substance doping, and used for the effective degradation of p-chlorophenol in water. The results showed that the Co-PEG-PbO 2 electrode surface was composed of small spherical particles β-PbO 2 , containing a small amount of Co 2 O 3 and PEG, and its grain size (8.985 nm) was the smallest in the same series of electrodes. The electrochemical tests results showed that the oxygen evolution reaction in Na 2 SO 4 solution was a sequential two-step charge transfer process, which was controlled by charge transfer and diffusion. The electrode had smaller oxygen evolution potential (1.40 V), larger exchange current density (j 0 = 1.164 × 10 −4 mA · cm −2 ), smaller charge transfer resistance (0.8778 Ω · cm 2 ) and larger concentration polarization resistance (1.335 Ω · cm 2 ), indicating that the Co-PEG-PbO 2 electrode had better electrocatalytic performance. The degradation of p-chlorophenol was controlled by diffusion and was oxidized by strong oxidizing · OH, which conforms to CE mechanism. Within the same degradation time, the electrode had a higher p-chlorophenol removal efficiency η (97.34%), higher TOC removal efficiency (64.25%), higher mineralization current efficiency (23.45%), and lower cell voltage. The accelerated life test showed that Co-PEG-PbO 2 electrode had the longest service life (280 min), which was 2.8, 1.8 and 2 times of PbO 2 electrode, Co-PbO 2 electrode and PEG-PbO 2 electrode, respectively. The electrocatalytic activity and stability of PbO 2 electrode can be effectively improved by structural adjustment and co-doping with Co 2+ and PEG, which can be used for the effective degradation of p-chlorophenol.

Biocatalytic Reduction of Formaldehyde to Methanol: Effect of pH on Enzyme Immobilization and Reactive Membrane Performance

Thermodynamic stabled CO2 molecules can be biocatalytically reduced to methanol via three cascade dehydrogenases (formate, formaldehyde and alcohol) with the aid of cofactor as the electron donor. In this study, Alcohol dehydrogenase (EC 1.1.1.1), the third step of the cascade enzymatic reaction which catalyzed formaldehyde (CHOH) to methanol (CH3OH) will be immobilized in an ultrafiltration membrane. The enzyme will be immobilized in the support layer of a poly(ether)sulfone (PES) membrane via a technique called fouling induced enzyme immobilization. The objective of this study is to evaluate the effect of varying pH (acid (pH 5), neutral (pH 7) and alkaline (pH 9)) of the feed solution during immobilization process of ADH in the membrane in terms of permeate flux, observed rejection, enzyme loading and fouling mechanism. The experiment was conducted in a pressure driven, dead-end stirred filtration cell. Reaction conversion and biocatalytic productivity will be also evaluated. The results showed that permeate flux for acid solution were the lowest during immobilization. High concentration polarization and fouling resistance cause lower observed rejection for pH 7 and 9. Enzyme loading for pH 5 give 73.8% loading rate which is the highest compared to 62.4% at pH 7 and 70.1% at pH 9. Meanwhile, the conversion rate during the reaction shows that reaction on fouled membrane showed more than 90% conversion for pH 5 and 7. The fouling model predicted that irreversible fouling occurs during enzyme immobilization at pH 7 with standard blocking mechanism while reversible fouling occurs at pH 5 and 9 with intermediate and complete blocking, respectively. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Mathematical modeling of vibratory shear‐enhanced nanofiltration in the preconcentration of coffee extracts for soluble coffee manufacturing

AbstractA semi‐empirical model was applied to evaluate the performance of a vibratory nanofiltration (NF) system, using 150‐Da TS80 NF membrane, for the preconcentration of coffee extracts in soluble coffee processing. The effects of transmembrane pressure (TMP), feed concentration, and module vibration on flux enhancement were correlated with membrane surface concentrations and fouling resistances under steady state operation. Vibratory shear thinned the boundary layer and increased the mass transfer coefficient of the solvent (water) by a factor of 3.5. Membrane surface concentrations and fouling resistances reduced by 60% compared with crossflow (CF) NF operation. These reductions enhanced permeate fluxes by about 2–3 times that of CF operation, with low flux decline. Feed concentration and TMP promoted polarization more than the negative effect of vibration. Osmotic pressure resistances were dominant under low feed concentrations and TMP. However, concentration polarization resistances exceeded osmotic pressure resistances as TMP and feed concentrations were increased. Real rejections relative to membrane surface chemical oxygen demand (COD) were above 0.99, indicating the potential of the operation to recover permeate that is reusable for ancillary plant operations. Overall, the experimental and theoretical permeate fluxes and CODs were in reasonable agreement, indicating the reliability of the model.Practical ApplicationsVibratory membrane processes alleviate the issues on membrane fouling that is advantageous when integrated into food and beverage processes. Its application as a coffee extract preconcentration alternative to thermal evaporation opens opportunities for sustainable soluble coffee production that can be adapted in other food and beverage industries. However, the unique dynamic nature of the vibratory membrane system challenges conventional approaches for understanding and predicting the mechanisms of the process. This gap limits the overall transferability of the technology to broader industry sectors. The semi‐empirical resistance‐in‐series model developed in this study correlates the important factors with the vibratory NF performance based on fundamental concepts: concentration polarization, osmotic pressure effects, and fouling resistance. The model is not only useful in managing membrane fouling in vibratory systems, but also in optimizing and developing alternative approaches on similar lines and their scale‐up to promote other industrial applications.

Highly active Mo doping TiO 2 as sulfur loaded matrix material for lithium‐sulfur batteries with excellent electrochemical performances

Lithium-sulfur batteries have attracted much attention for a long time owing to their high theoretical specific capacity. In this paper, a type of highly active Mo doping TiO2 as sulfur loaded matrix material has been synthesized by a facile solvothermal method. X-ray diffraction and Raman spectrum tests show that Mo atom can enter into the interlayer of TiO2 crystal face and increase the interplanar spacing of titanium dioxide in order to possess a higher electrochemical activity. Small particles morphology and uniform particle size can be evidently observed by scanning electron microscope and after sulfur loading (1:1), it still retains the similar morphology as matrix material. This illustrates that a considerable amount of sulfur has penetrated into the matrix material in order to achieve the ideal sulfur loading effect. When used as electrode active material, it displays the lowest electrochemical and concentration polarization resistance and the specific capacities can reach 1483.08, 1208.57, and 1004.17 mAh g−1 at 0.1, 0.2, and 0.5 C current rates and after 150 cycles, the capacity retention is over 60%. When the sulfur loading mass ratio increases to 1:2 (Mo/TiO2:S), the sulfur composite cathode still maintains considerable lithium-ion diffusion channels and 753.54 mAh g−1 of specific discharge capacity at 0.5 C current rate.

Improved hydrogen separation performance of asymmetric oxygen transport membranes by grooving in the porous support layer

Hydrogen separation through oxygen transport membranes (OTMs) has attracted much attention. Asymmetric membranes with thin dense layers provide low bulk diffusion resistances and high overall hydrogen separation performances. However, the resistance in the porous support layer (PSL) limits the overall separation performance significantly. Engineering the structure of the PSL is an appropriate way to enable fast gas transport and increase the separation performance. There is no relevant research on studying the influence of the PSL on hydrogen separation performance so far. Herein, we prepared Ce0.85Sm0.15O1.925 – Sm0.6Sr0.4Cr0.3Fe0.7O3-δ (SDC-SSCF) asymmetric membranes with straight grooves in PSL by tape-casting and laser grooving. A ~30% improvement in the hydrogen separation rate was achieved by grooving in the PSLs. It indicates that the grooves may reduce the concentration polarization resistance in PSL for the hydrogen separation process. This work provides a straight evidence on optimizing the structures of PSL for improving the hydrogen separation performance of the membrane reactors.

Extended performance study of forward osmosis during wastewater reclamation: Quantification of fouling-based concentration polarization effects on the flux decline

The long-term performance of forward osmosis during simulated wastewater reclamation was investigated for 120 h operation with a focus upon the influence of flux on flux decline and the synergistic effect of fouling on concentration polarization. Our comprehensive investigation focused on different fluxes (25; 30; 34 LMH) for simulated wastewater containing either a high protein or a low protein fraction. Compared to an initial flux of 25 LMH, operation at an initial 34 LMH favored the formation of a thicker and more compact cake layer which resulted in significant increase in both cake structural parameter (four-fold) and cake layer enhanced concentration polarization (ten-fold). After 40 h operation without physical cleaning the additional effect of cake layer enhanced concentration polarization and fouling resistance consumed 25% of the total driving force; the significant internal concentration polarization still had the greatest impact. In contrast operation at the lower flux of 25 LMH generated less fouling with a lower cake structural parameter (119 μm). The resultant flux decline was only 3% in contrast to the 15–18% found for the higher flux of 34 LMH. For operation above an initial 30 LMH it was found that FO fouling became irreversible if the wastewater contained a high protein fraction. Overall for a thin film composite membrane and a wastewater with a foulant concentration of 160 mg/L an initial flux of 25 LMH is the recommended threshold; this is 25% less that the critical value determined in earlier short-term studies.

Nitrate removal studies on polyurea membrane using nanofiltration system – membrane characterization and model development

Abstract Desalination of nitrates from brackish water is prominent in the coastal areas due to excessive disposal of pesticides by agricultural industries. Nowadays, membrane processes are growing tremendously for the desalination of brackish water. In this context, polyurea (PU) could be a useful membrane material for the treatment of brackish water. The present work deals with the removal of nitrates from synthetic water using PU membranes by nanofiltration (NF) process. Polyurea thin film composite (PU-TFC) membranes were prepared by interfacial polymerization followed by thermal crosslinking and characterized using Fourier transformed infrared spectral (FTIR), X-ray diffraction (XRD), scanning electron microscopy– energy dispersion X-ray spectroscopy (SEM–EDS), Atomic force microscopy (AFM), thermogravimetric (TGA), and universal testing machine (UTM) for structural analysis, crystallinity, morphological, compositional, thermal and mechanical properties, respectively. Experimental studies were conducted on an NF pilot plant by varying operating pressure from 2 to 10 bar and feed nitrate concentration from 60 to 200 mg/L for evaluating PU membrane performance. Experimental observations revealed a maximum water flux of 30.6 L/m2 h and nitrate rejection of 97.2% at a pressure of 10 bar for feed containing 140 mg/L of nitrate. A mass transfer model was developed on the basis of solution–diffusion mechanism for a semi-batch NF process by considering cake enhanced concentration polarization model, for laminar flow with feed recycle, using a plate and frame membrane module. A generic semi-batch NF process model was integrated taking into account concentration polarization and fouling layer resistance. The integrated model was successfully compared with existing data in literature and could be used for process scale-up. Due to the merits of hydrophilicity, negative charge, high thermal and mechanical resistance, the PU membrane can be termed as a low cost, commercially viable and ecofriendly barrier for separation of nitrates.

High Rate Capability of All-Solid-State Lithium Batteries Using Quasi-Solid-State Electrolytes Containing Ionic Liquids

Here we demonstrate a high rate capability of all-solid-state lithium batteries using quasi-solid-state electrolytes containing an ionic liquid. We fabricated solid-state electrolyte using an ionic liquid: 1 mol l−1 lithium bis(fluorosulfonyl) imide dissolved 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (LiFSI/EMI-FSI) and fumed silica nanoparticles with a variety of volume fractions. The fabricated freestanding film with 85% volume fraction of LiFSI/EMI-FSI exhibited an ionic conductivity and self-diffusion coefficient of lithium-containing species; 10.2 mS cm−1 and 3.3 × 10−11 m2 s−1 at 35 °C. We revealed that the increase in the volume fraction of the LiFSI/EMI-FSI led to the decrease in concentration polarization resistance, leading to an enhanced rate capability in Li∣LiFePO4 batteries. The fabricated Li∣LiFePO4 batteries using freestanding electrolyte films with 85 vol% LiFSI/EMI-FSI exhibited a high capacity (>150 mAh g−1) at 1 C (0.6 mA cm−2) based on that at 0.1 C. Further, we fabricated bipolar-type all-solid-state lithium batteries assembled by stacking of Li∣LiFePO4 cell components in a single package. The bipolar-type lithium batteries exhibited the increased packing energy density, depending on the number of stacked cells. These results open opportunities of designing all-solid-state lithium batteries for high energy and power density using quasi-solid-state electrolytes.

Role of concentration polarization in cross flow micellar enhanced ultrafiltration of cadmium with low surfactant concentration

Concentration polarization is an important issue in micellar enhanced ultrafiltration (MEUF) of wastewater containing heavy metal ions at low surfactant concentrations. In this paper, we studied removal of Cd(Ⅱ) by cross flow MEUF at low sodium dodecyl sulfate (SDS) concentration levels, and the role of concentration polarization in flux decline and Cd(Ⅱ) rejection was emphasized. Concentration polarization resistance and SDS concentration near membrane were calculated to characterize concentration polarization. The results showed that SDS concentration near membrane was 13 mM when feed concentration was merely 0.8 mM. By combining phase diagram of SDS, structures of SDS micelles in concentration polarization layer were deduced and thin layer structure transformed to porous structure formed by accumulated globular micelles when SDS concentration increased. Although micelles formed in concentration polarization layer was responsible for flux decline, they also provided adsorption sites for Cd(Ⅱ).

Zinc Recovery through Electrolytic Refinement Using Insoluble Ir + Sn + Ta + PdOx/Ti Cathode to Reduce Electrical Energy Use.

In this study, an alumina (Al) anode, a lead cathode, and insoluble catalytic cathodes (IrOx, PdOx, TaOx, and SnOx) were used as electrodes to enhance zinc recovery. The traditionally used iron electrode and insoluble catalytic electrodes were also used to compare the recovery yield when different types of electrodes were subjected to the same amount of energy. The lead electrode showed over 5000 Ω higher electrode resistance than did the insoluble catalytic electrode, leading to overpotential requiring higher electrical energy. As electrical energy used by the lead and the insoluble catalytic electrodes were 2498.97 and 2262.37 kwh/ton-Zn, respectively, electrical energy can be reduced by 10% when using an insoluble catalytic electrode compared to that when using a lead electrode. Using recovery time (1–4 h) and current density (100–500 A/m2) as variables, the activation, concentration polarization, and electrode resistance were measured for each condition to find the optimum condition for zinc recovery. A recovery yield of about 77% was obtained for up to 3 h of zinc recovery time at a current density of 200 A/m2, which is lower than that (about 80%) obtained at 300 A/m2. After 3 h of recovery time, electrode resistance (Zn concentration reduction, hydrogen generation on electrode surface) and overpotential increase with time decreased at a current density of 200 A/m2, leading to a significant increase in zinc recovery yield (95%).

CFD analysis on sorption-enhanced glycerol reforming in a membrane-assisted fluidized bed reactor

In this work, a three-dimensional simulation of the sorption-enhanced glycerol reforming (SEGR) process for hydrogen production in a membrane-assisted fluidized bed reactor is carried out by means of the multi-fluid model coupling with chemical kinetics model and membrane separation model. The mutual interaction mechanism of the two enhancing methods including membrane hydrogen separation and carbon dioxide sorption is revealed. The results indicate that the carbon dioxide sorption can hinder the concentration polarization resistance and improve the hydrogen permeation rate while the scope of densified zones is enlarged. Meanwhile, the increase of hydrogen separation degree is also beneficial to the carbon dioxide sorption performance. In addition, the utilization of bi-functional sorbent-catalyst particles can further promote the sorption-enhanced reforming process compared to the conventional two-pellet design.

Improving the Efficiency of High-Temperature Electrolysis of Carbon Dioxide in a Solid Oxide Cell

This work focuses on the development of a bespoke rig which allows for the simultaneous use of non-thermal plasmas (NTPs), oscillating gas flow via a Desai-Zimmerman Fluidic Oscillator (DZFO) and a Solid Oxide Cell (SOC) to create a highly efficient energy conversion device to facilitate the reduction of CO2 to CO. Both fluidic oscillation and NTPs have the potential to reduce resistances in a SOC, key to furthering their commercialisation. The potential role of NTPs in improving the kinetics and efficiency of reactions relevant to CO2 reduction, such as the dissociation of CO2, is presented. Performance improvements using a rapidly oscillating gas flow, provided by the DZFO, to minimise concentration polarisation resistance by disrupting boundary layer formation and increasing overall efficiency are also discussed. The intersection of these technologies provide a path for a paradigm shift in the ability to convert waste CO2 into high value feedstock using renewable energy.

Membrane fouling in a hybrid process of enhanced coagulation at high coagulant dosage and cross-flow ultrafiltration for deinking wastewater tertiary treatment

A hybrid process of enhanced coagulation at a high dosage of polyaluminum chloride and flat-sheet cross-flow ultrafiltration was used for the advanced treatment of the effluent from a biological treatment process of deinking wastewater in a paper mill. The experimental results obtained by a small-scale continuous laboratory experimental device showed that the absorption resistance was significantly lower than the membrane intrinsic resistance, the concentration polarization resistance, the pore blocking resistance, and the cake layer resistance and so it can be ignored. With increasing polyaluminum chloride dosage from 0 to 2,000 mgL-1, the total membrane filtration resistance decreased and the membrane flux increased, but the concentration polarization resistance increased. With the increase in cross flow velocity, the total membrane filtration resistance, the pore blocking resistance, the layer resistance, and the concentration polarization resistance all decreased, and consequently, the membrane flux increased. With regard to the concentration polarization resistance, the cross flow velocity had a more significant effect than the trans-membrane pressure. But the trans-membrane pressure had a more significant effect on the layer resistance, the pore blocking resistance, and the total membrane filtration resistance than the cross flow velocity. The filtration resistance at the polyaluminium chloride dosage of <1,000 mgL-1 could be ranked as follows: the membrane intrinsic resistance > the pore blocking resistance > the layer resistance > the concentration polarization resistance> the absorption resistance. But it was the membrane intrinsic resistance > the concentration polarization resistance > the pore blocking resistance > the layer resistance > the absorption resistance at the dosage of ≥1,000 mgL-1. The results are helpful for the membrane fouling control and can promote the application of flat-sheet cross-flow membrane process, resultantly improving the reclaim and reuse of deinking wastewater, and reducing the emission of contaminants in deinking wastewater.