Regulating Li-Ion Transport through Ultrathin Molecular Membrane to Enable High-Performance All-Solid-State-Battery.

Solid-state lithium metal batteries with garnet-type electrolyte provide several advantages over conventional lithium-ion batteries, especially for safety and energy density. However, a few grand challenges such as the propagation of Li dendrites, poor interfacial contact between the solid electrolyte and the electrodes, and formation of lithium carbonate during ambient exposure over the solid-state electrolyte prevent the viability of such batteries. Herein, an ultrathin sub-nanometer porous carbon nanomembrane (CNM) is employed on the surface of solid-state electrolyte (SSE) that increases the adhesion of SSE with electrodes, prevents lithium carbonate formation over the surface, regulates the flow of Li-ions, and blocks any electronic leakage. The sub-nanometer scale pores in CNM allow rapid permeation of Li-ions across the electrode-electrolyte interface without the presence of any liquid medium. Additionally, CNM suppresses the propagation of Li dendrites by over sevenfold up to a current density of 0.7 mA cm-2 and enables the cycling of all-solid-state batteries at low stack pressure of 2 MPa using LiFePO4 cathode and Li metal anode. The CNM provides chemical stability to the solid electrolyte for over 4 weeks of ambient exposure with less than a 4% increase in surface impurities.

Review of functionalized nano porous membranes for desalination and water purification: MD simulations perspective.

Today, it is known that most of the water sources in the world are either drying out or contaminated. With the increasing population, the water demand is increasing drastically almost in every sector each year, which makes processes like water treatment and desalination one of the most critical environmental subjects of the future. Therefore, developing energy-efficient and faster methods are a must for the industry. Using functional groups on the membranes is known to be an effective way to develop shorter routes for water treatment. Accordingly, a review of nano-porous structures having functional groups used or designed for desalination and water treatment is presented in this study. A systematic scan has been conducted in the literature for the studies performed by molecular dynamics simulations. The selected studies have been classified according to membrane geometry, actuation mechanism, functionalized groups, and contaminant materials. Permeability, rejection rate, pressure, and temperature ranges are compiled for all of the studies examined. It has been observed that the pore size of a well-designed membrane should be small enough to reject contaminant molecules, atoms, or ions but wide enough to allow high water permeation. Adding functional groups to membranes is observed to affect the permeability and the rejection rate. In general, hydrophilic functional groups around the pores increase membrane permeability. In contrast, hydrophobic ones decrease the permeability. Besides affecting water permeation, the usage of charged functional groups mainly affects the rejection rate of ions and charged molecules.

Hydrazine-Enabled One-Step Synthesis of Metal Nanoparticle-Functionalized Gradient Porous Poly(ionic liquid) Membranes.

In this communication, a one-step synthetic route is reported toward free-standing metal-nanoparticle-functionalized gradient porous polyelectrolyte membranes (PPMs). The membranes are produced by soaking a glass-plate-supported blend film that consists of a hydrophobic poly(ionic liquid) (PIL), poly(acrylic acid), and a metal salt, into an aqueous hydrazine solution. Upon diffusion of water and hydrazine molecules into the blend film, a phase separation process of the hydrophobic PIL and an ionic crosslinking reaction via interpolyelectrolyte complexation occur side by side to form the PPM. Simultaneously, due to the reductive nature of hydrazine, the metal salt inside the polymer blend film is reduced in situ by hydrazine into metal nanoparticles that anchor onto the PPM. The as-obtained hybrid porous membrane is proven functional in the catalytic reduction of p-nitrophenol. This one-step method to grow metal nanoparticles and gradient porous membranes can simplify future fabrication processes of multifunctional PPMs.

Porous Electroactive and Biodegradable Polyurethane Membrane through Self-Doping Organogel.

In order to improve the processability of conductive polyurethane (CPU) containing aniline oligomers, a new CPU containing aniline trimer (AT) and l-lysine (PUAT) are designed and synthesized. Further, the 3D porous PUAT membranes have been prepared by a simple gel cooperated with freeze-drying method. Chemical testings and conductive properties testify a self- doping model of PUAT based on the rich electronic l-lysine and electroaffinity AT moities. The self-doping behavior further endows the PUAT copolymers specific characteristics such as high electrical conductivity and the formation of the polaron lattice like-structure in good solvent dimethyl sulfoxide. The combination of organogel and freeze-drying could prevent the collapse of pore structure when the copolymers are molded as membranes. The synergistic effect of l-lysine and AT components has a strong influence on the dissolution, degradation, thermal stability, and mechanical properties of PUAT. The excellent properties of PUAT would broad the application of conductive polymers in biomedicine field.

Photo-Driven Ion Transport for a Photodetector Based on an Asymmetric Carbon Nitride Nanotube Membrane.

Conventional photosensing devices work mainly by electron processing and transport, while visual systems in intelligence work by integrative ion/electron signals. To realize smarter photodetectors, some photoionic device or the combination of ionic and electronic devices are necessary. Now, an ion-transport-based self-powered photodetector is presented based on an asymmetric carbon nitride nanotube membrane, which can realize fast, selective, and stable light detection while being self-powered. Local charges are continuously generated at the irradiated side of the membrane, and none (fewer) at the non-irradiated side. The resulting surface charge gradient in carbon nitride nanotube will drive ion transport in the cavity, thus realizing the function of ionic photodetector. With advantages of low cost and easy fabrication process, the concept of ionic photodetectors based on carbon nitride anticipates wide applications for semiconductor biointerfaces.

A Novel Thermoresponsive Catalytic Membrane with Multiscale Pores Prepared via Vapor-Induced Phase Separation.

A novel thermoresponsive catalytic polyethersulfone membrane with multiscale pores is developed by constructing silver nanoparticles (Ag NPs) loaded poly(N-isopropylacrylamide) (PNIPAM) nanogels on pore walls of cellular pores as thermoresponsive gates and catalysts via vapor-induced phase separation. The Ag NPs are stably immobilized on the PNIPAM nanogels by an in situ reduction method based on the versatile adhesion and reduction properties of polydopamine. The micrometer cellular pores decorated with Ag NPs loaded PNIPAM nanogels are formed throughout the membrane and act as numerous microreactors with a large pore surface. The proposed membrane exhibits both satisfactory thermoresponsive characteristics and stable catalytic properties. The effects of operation temperature and reactant concentration of feed solution on the catalytic properties are investigated systematically. The results show that the apparent kinetic rate constant of catalytic reduction of 4-nitrophenol (4-NP) in water by reductant sodium borohydride (NaBH4 ), is ranging from 3.7 to 37.9 min-1 at temperatures from 20 to 45 ºC and the molar ratio of NaBH4 to 4-NP from 100:1 to 500:1. When the reactant concentration in feed solution fluctuates, the permeability or throughput of the membrane is simply adjusted by virtue of the thermoresponsive characteristics of membranes to achieve high catalytic conversion of reactant.

Computer-aided analysis of micro-morphological structure of porous membranes.

BACKGROUND: The paper presents an approach and computer-aided method of numerical evaluation of the quality of porous membranes used as scaffolds for cultivation of chondrocytes in regeneration of biological tissues. MATERIALS: The scanning electron microscope (SEM) images of 300× and 1000× magnification presenting the sections of artificial polyvinylpyrrolidone membranes obtained in two alternative production processes are examined. THEORY AND METHODS: There is presented a combined morphological and statistical method of the assessment of artificial membranes' porosity, based on computer-aided segmentation and analysis of the size and shape of pores. Theoretical backgrounds of description pores as irregular objects in discrete 3-dimensional space are presented. The parameters characterizing the quality of pores: pores irregularity coefficient and pores density are defined. The quality of the examined specimens of materials is characterized by the size (mean 2-dimensional section areas) of pores. The main concept presented in the paper is the extraction of lacking information concerning the third dimension of pores from the 2-dimensional SEM images of their sections. Two approaches to evaluation of the parameters characterizing pores on the basis of computer-aided analysis of their cross-sections are proposed: (1) based on statistical extension of geometrical data and (2) based on analysis of brightness profiles. The corresponding methods are based on the assumption of isotropy of the examined porous materials. The results of automatic measurements of the areas of pores, lengths of their chords and recording the brightness profiles along fixed lines crossing the analyzed images are illustrated by examples. CONCLUSIONS: Practical usefulness of the proposed methods to evaluation of the quality of porous membranes consists in their ability to be used in case if alternative methods for some reasons cannot be used.

Biomimetic Peptide-Gated Nanoporous Membrane for On-Demand Molecule Transport.

The controllable molecule transport is crucial to realize many highly valuable applications both in vivo and in vitro. Nanoporous membranes, with nanoscopic pores, high porosity, uniform pore dimensions, and controllable surface chemical properties, hold tremendous potential to achieve this function. Herein, we report a nano-gating system for on-demand molecule transport based on a peptide-gated nanoporous membrane. Acting as gatekeeper, the peptides introduced to the nanoporous membrane provide an opportunity to realize on-demand on-off states via reversible conformational switching of the peptides. This nano-gating system offers sustained release and can be used as a sophisticated molecule transport platform for localized drug delivery with a feedback function.

A Low-Cost Neutral Zinc-Iron Flow Battery with High Energy Density for Stationary Energy Storage.

Flow batteries (FBs) are one of the most promising stationary energy-storage devices for storing renewable energy. However, commercial progress of FBs is limited by their high cost and low energy density. A neutral zinc-iron FB with very low cost and high energy density is presented. By using highly soluble FeCl2 /ZnBr2 species, a charge energy density of 56.30 Wh L-1 can be achieved. DFT calculations demonstrated that glycine can combine with iron to suppress hydrolysis and crossover of Fe3+ /Fe2+ . The results indicated that an energy efficiency of 86.66 % can be obtained at 40 mA cm-2 and the battery can run stably for more than 100 cycles. Furthermore, a low-cost porous membrane was employed to lower the capital cost to less than $ 50 per kWh, which was the lowest value that has ever been reported. Combining the features of low cost, high energy density and high energy efficiency, the neutral zinc-iron FB is a promising candidate for stationary energy-storage applications.

A Highly Ion-Selective Zeolite Flake Layer on Porous Membranes for Flow Battery Applications.

Zeolites are crystalline microporous aluminosilicates with periodic arrangements of cages and well-defined channels, which make them very suitable for separating ions of different sizes, and thus also for use in battery applications. Herein, an ultra-thin ZSM-35 zeolite flake was introduced onto a poly(ether sulfone) based porous membrane. The pore size of the zeolite (ca. 0.5 nm) is intermediary between that of hydrated vanadium ions (>0.6 nm) and protons (<0.24 nm). The resultant membrane can thus be used to perfectly separate vanadium ions and protons, making this technology useful in vanadium flow batteries (VFB). A VFB with a zeolite-coated membrane exhibits a columbic efficiency of >99 % and an energy efficiency of >81 % at 200 mA cm(-2), which is by far the highest value ever reported. These convincing results indicate that zeolite-coated membranes are promising in battery applications.

Porous Membranes Built Up from Hydrophilic Poly(ionic liquid)s.

Porous polymer membranes made via electrostatic complexation are fabricated from a water-soluble poly(ionic liquid) (PIL) for the first time. The porous structure is formed as a consequence of simultaneous phase separation of the PIL and ionic complexation with an acid, which occurred in a basic solution of a nonsolvent for the PIL. These membranes have a stimuli-responsive porosity, with open and closed pores in isopropanol and in water, respectively. This property is quantitatively demonstrated in filtration experiments, where water is passing much slower through the membranes than isopropanol.

Study of carbamate-modified disiloxane in porous PVDF-HFP membranes: new electrolytes/separators for lithium-ion batteries.

A gel electrolyte membrane is obtained through the absorption of a carbamate-modified liquid disiloxane-containing lithium bis(trifluoromethane)sulfonimide (LiTFSI) by using macroporous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) membranes. The porous membranes are prepared by means of a phase inversion technique. The resulting gel electrolyte membrane is studied by using differential scanning calorimetry, Fourier-transform infrared (FTIR) spectroscopy, and microscope mapping through coherent anti-Stokes Raman scattering (CARS) confocal microscopy and impedance spectroscopy. The ionic conductivity of the gel electrolyte is 10(-4) S cm(-1) at 20 °C. FTIR spectroscopy reveals interactions between LiTFSI and the carbonyl moiety of the disiloxane. No interactions between LiTFSI and PVDF-HFP or between disiloxane and PVDF-HFP are detected by FTIR spectroscopy. Furthermore, the distribution of the α and ß/γ phases of PVDF-HFP and the homogeneous distribution of disiloxane/LiTFSI in the gel electrolyte membranes are examined by FTIR mapping. CARS confocal microscopy is used to image the three-dimensional interconnectivity, which reveals a reticulated structure of macrovoids in the porous PVDF-HFP framework. Owing to properties such as electrochemical and thermal stability of the disiloxane-based liquid electrolyte and the mechanical stability of the porous PVDF-HFP membrane, the gel electrolyte membranes presented herein are promising candidates for applications as electrolytes/separators in lithium-ion batteries.

Salt-induced fabrication of superhydrophilic and underwater superoleophobic PAA-g-PVDF membranes for effective separation of oil-in-water emulsions.

Conventional polymer membranes suffer from low flux and serious fouling when used for treating emulsified oil/water mixtures. Reported herein is the fabrication of a novel superhydrophilic and underwater superoleophobic poly(acrylic acid)-grafted PVDF filtration membrane using a salt-induced phase-inversion approach. A hierarchical micro/nanoscale structure is constructed on the membrane surface and endows it with a superhydrophilic/underwater superoleophobic property. The membrane separates both surfactant-free and surfactant-stabilized oil-in-water emulsions under either a small applied pressure (<0.3 bar) or gravity, with high separation efficiency and high flux, which is one to two orders of magnitude higher than those of commercial filtration membranes having a similar permeation property. The membrane exhibits an excellent antifouling property and is easily recycled for long-term use. The outstanding performance of the membrane and the efficient, energy and cost-effective preparation process highlight its potential for practical applications.

Breathing pores on command: redox-responsive spongy membranes from poly(ferrocenylsilane)s.

Redox-responsive porous membranes can be readily formed by electrostatic complexation between redox active poly(ferrocenylsilane) PFS-based poly(ionic liquid)s and organic acids. Redox-induced changes on this membrane demonstrated reversible switching between more open and more closed porous structures. By taking advantage of the structure changes in the oxidized and reduced states, the porous membrane exhibits reversible permeability control and shows great potential in gated filtration, catalysis, and controlled release.

Coaxial Electrospun Porous Core-Shell Nanofibrous Membranes for Photodegradation of Organic Dyes.

In this study, a series of AgCl/ZnO-loaded nanofibrous membranes were prepared using coaxial electrospinning. Their physical and chemical characteristics were evaluated by SEM, TEM, XRD, XPS, IR, PL, and UV-visible spectrometer, and the photocatalytic experiments using methylene blue (MB) as a model pollutant. The formation of AgCl/ZnO heterojunction and the structure of core-shell nanofibers with porous shell layer were confirmed. AgCl/ZnO photocatalysts were also effectively loaded onto the surfaces of the porous core-shell nanofibers. The results of photocatalytic experiments revealed that the AgCl/ZnO (MAgCl:MZnO = 5:5)-loaded nanofibrous membrane achieved a degradation efficiency of 98% in just 70 min and maintained a photocatalytic efficiency exceeding 95% over the first five experimental cycles, which successfully addressed the issues of photocatalytic efficiency loss during the photodegradation of MB with AgCl/ZnO nanoparticles as photocatalyst. The photodegradation mechanism was also researched and proposed.

Highly Stretchable Thermoplastic Polyurethane Separators for Li-Ion Batteries Based on Non-Solvent-Induced Phase Separation Method.

The growing interest in wearable and portable devices has stimulated the need for flexible and stretchable lithium-ion batteries (LiBs). A crucial component in these batteries is the separator, which provides a pathway for Li-ion transfer and prevents electrode contact. In a flexible and stretchable LiB, the separator must exhibit stretchability and elasticity akin to its existing counterparts. Here, we developed a non-modified thermoplastic polyurethane (TPU) separator using the non-solvent induced phase separation (NIPS) technique. We compared their performance with commercially available polypropylene (PP) separators. Our results demonstrate that TPU separators exhibit superior elasticity based on repeated stretch/release tests with excellent thermal stability and electrolyte wettability. Furthermore, our findings confirm that TPU separators, even after being repeatedly stretched and released, can function effectively without severe damage in a fabricated coin cell LiB with high oxidative stability, as evidenced by linear sweep voltammetry, like commercially available separators.

Enhancing proton transport in polyvinylidenedifluoride membranes and reducing biofouling for improved hydrogen production in microbial electrolysis cells.

Hydrophilic porous membranes, exemplified by polyvinylidene fluoride (PVDF) membranes, have demonstrated significant potential for replacing ion exchange membranes in microbial electrolysis cells (MECs). Membrane fouling remains a major challenge in MECs, impeding proton transport and consequently limiting hydrogen production. This study aims to investigate a synergistic antifouling strategy for PVDF membrane through the incorporation of a coating composed of polydopamine (PDA), polyethyleneimine (PEI), and silver nanoparticles (AgNPs). The PDA-PEI-Ag@PVDF membrane not only effectively mitigates fouling through steric and electrostatic repulsion forces, but also amplifies ion transport by facilitating water diffusion and electromigration. The PDA-PEI-Ag@PVDF membrane exhibited a reduced membrane resistance of 1.01 mΩ m2 and PDA-PEI-Ag modifying PVDF membrane was found to be effective in enhancing the proton transportation of PVDF membrane. Therefore, the enhanced hydrogen production rate of 2.65 ± 0.02 m3/m3/d was achieved in PDA-PEI-Ag@PVDF-MECs.

Large-Scale Fabrication of Freestanding Polymer Ultrathin Porous Membranes for Transparent Transwell Coculture Systems.

Advancements in cell coculture systems with porous membranes have facilitated the simulation of human-like in vitro microenvironments for diverse biomedical applications. However, conventional Transwell membranes face limitations in low porosity (ca. 6%) and optical opacity due to their large thickness (ca. 10 µm). In this study, we demonstrated a one-step, large-scale fabrication of freestanding polymer ultrathin porous (PUP) membranes with thicknesses of hundreds of nanometers. PUP membranes were produced by using a gap-controlled bar-coating process combined with polymer blend phase separation. They are 20 times thinner than Transwell membranes, possessing 3-fold higher porosity and exhibiting high transparency. These membranes demonstrate outstanding molecular permeability and significantly reduce the cell-cell distance, thereby facilitating efficient signal exchange pathways between cells. This research enables the establishment of a cutting-edge in vitro cell coculture system, enhancing optical transparency, and streamlining the large-scale manufacturing of porous membranes.

Conductive carbon paint: An efficient way to electrodeposit metallic nanowires by using porous membranes.

The present work demonstrates that conductive carbon paint, used for sample preparation in electron microscopy, can be a more straightforward and as-effective substitute for the metallic layer deposition usually used for the electrodeposition of metallic nanowires within porous membranes. AFM images demonstrated the good surface quality of the carbon layer. Raman spectroscopy confirmed the high crystallinity of carbon and high density of π-electrons. The electrical conductivity of the carbon layer was estimated using the linear sweep voltammetry technique. This new cathode was employed to grow continuous (Ni) and composition-modulated (Ni/Cu) nanowires within alumina templates, starting from aqueous solutions of Ni2+ and Cu2+ mixed salts. The obtention of metallic copper and nickel, and their separation can be readily observed by scanning electron microscopy and elemental mapping by EDS.

Novel glass-based membranes for Cu adsorption: From alkali activation to sintering.

A porous membrane was developed through alkali activation of pharmaceutical boro-alumino-silicate glass powders suspended in diluted NaOH and KOH aqueous solutions (2.5 M). A consolidated porous structure was obtained by the binding of unreacted particles mediated by a surface gel, developed upon drying of the suspensions and their curing at 40 °C for 14 days. The binding phase was sufficiently stable to resist immersion in boiling water and in acidic solutions. Copper adsorption tests were carried out under acidic pH, immersing the membranes in a Cu(NO3)2 solution for different periods of time. To determine the effect of surface washing on capture of copper ions, adsorption experiments with washed and unwashed membranes were also carried out, at varying pH. It was determined that the adsorption kinetics follow the pseudo-second-order kinetic model. The main adsorption mechanism observed is the electrostatic interaction between the negative surface charge of the washed membrane and the Cu2+ ions present in solution. An adsorption higher than 60% was observed at pH = 5, while at pH = 2 the efficiency decreased due to the presence of H3O+ ions. To ensure immobilization of copper, the membranes were densified by viscous flow sintering at a moderate temperature (700 °C). Leaching tests on membranes demonstrated the efficiency of the process in terms of copper ions immobilization.