Non-solvent Induced Phase Separation Research Articles

Novel Ultrafiltration Polyethersulfone Membranes Blended with Carrageenan

The development of ultrafiltration (UF) polymeric membranes with high flux and enhanced antifouling properties bridges a critical gap in the polymeric membrane fabrication research field. In the present work, the preparation of novel PES membranes incorporated with carrageenan (CAR), which is a natural polymer derived from edible red seaweed, is reported for the first time. The PES/CAR membranes were prepared by using the nonsolvent-induced phase separation (NIPS) method at 0.1–4.0 wt.% CAR loadings in the casting solutions. The use of dimethylsulfoxide (DMSO), which is a bio-based and low-toxic solvent, is reported. Scanning electron microscopy, atomic force microscopy, water contact angle, porosity, and zeta potential measurements were used to evaluate the surface morphology, structure, pore size, hydrophilicity, and surface charge of the prepared membranes. The filtration performance of PES/CAR membranes was tested with bovine serum albumin (BSA) solutions. It was shown that CAR incorporation in the casting solutions notably increased hydrophilicity, porosity, pore size, surface charge, and fouling resistance of the prepared membranes compared with plain PES membranes due to the hydrophilic nature and pore-forming properties of CAR. The PES/CAR membranes showed a significant reduction in irreversible and total fouling during filtration of BSA solutions by 38% and 32%, respectively, an enhancement in the flux recovery ratio by 20–40%, and an improvement in mechanical properties by 1.5-fold when compared with plain PES membranes. The findings of the present study indicate that CAR can be used as a promising additive for the development of PES UF membranes with enhanced properties and performance for water treatment applications.

Preparation of polyvinylidene fluoride membranes with enhanced hydrophobicity and its applications in chromium recovery using supported liquid membranes in practical scale

This study focuses on the development of polyvinylidene fluoride (PDVF) membranes with enhanced hydrophobicity and their application for supported liquid membrane (SLM)-based solvent extraction. Flat sheet membranes were prepared via vapor-induced phase separation (VIPS), followed by non-solvent-induced phase separation (NIPS). PVDF flat sheet membrane was prepared with different solvents, namely N-methylpyrrolidone, dimethylformamide (DMF), dimethylacetamide, and dimethylsulfoxide, and at different VIPS times. The effect of different solvents and VIPS time on the membrane characteristics and performance was studied. PVDF membrane prepared with DMF solvent with VIPS time of 7.5 min gave optimum results in terms of membrane characteristics and performance with a water contact angle of 95.5°. The optimized PVDF flat sheet membrane was used as support in a SLM setup for the extraction and recovery of chromium from a simulated aqueous feed solution similar to tannery effluent with concentrations ranging from 5 to 75 ppm. Dodecane, modified with 1-dodecanol and decalin, was used as an organic solvent with tri-caprylmethylammonium chloride (Aliquat 336) as an extractant. NaNO3 solution was used as a stripping solution. The processes of extraction and stripping were carried out simultaneously in a single-step operation to recover chromium. The extraction of chromium achieved in 3 h using an in-house-prepared hydrophobic PVDF membrane as support for the liquid membrane varies from 63.08% for feed containing 5 ppm chromium to 50.59% for feed containing 75 ppm chromium, with a maximum extraction of 70.92% for feed with 50 ppm chromium.

Optimization of Polyelectrolyte Coacervate Membranes via Aqueous Phase Separation.

Polymeric membranes fabricated via the nonsolvent-induced phase separation process rely heavily on toxic aprotic organic solvents, like N-methyl-pyrrolidine (NMP) and dimethylformamide. We suggest that the "saloplastic" nature of polyelectrolyte complexes (PECs) makes them an excellent candidate for fabricating next-generation water purification membranes that use a more sustainable aqueous phase separation process. In this study, we investigate how the properties of PECs and their interactions with salt can form pore-containing membranes from the strong polyelectrolytes poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDADMAC) in the presence of potassium bromide (KBr). How the single-phase polymer-rich (coacervate) dope solution and coagulation bath impacted the formation, morphology, and pure water permeance (PWP) of the membranes was systematically evaluated by using scanning electron microscopy and dead-end filtration tests. The impact of a salt annealing post-treatment process was also tested; these treated PEC membranes exhibited a PWP of 6.2 L m-2 h-1 bar-1 and a dye removal of 91.7% and 80.5% for methyl orange and methylene blue, respectively, which are on par with commercial poly(ether sulfone) nanofiltration membranes. For the first time, we have demonstrated the ability of the PEC membranes to repel Escherichia coli bacteria under static conditions. Our fundamental study of polyelectrolyte membrane pore-forming mechanisms and separation performance could help drive the future development of sustainable materials for membrane-based separations.

Characteristics of Polyethersulfone Membranes Modified by Silika and Nanocellulose Extracted from Biomass as Additives

Polyethersulfone membranes were fabricated using non-solvent-induced phase separation (NIPS) with silica and nanocellulose additives extracted from rice husk ash and genjer (Limnocharis flava). N-methyl pyrrolidone served as the solvent. The study aimed to prepare membranes with diverse characteristics by incorporating various combinations of additives. Silica acted as a pore-forming agent, while nanocellulose enhanced membrane hydrophilicity. Characterization techniques included Fourier-transform infrared spectroscopy (FTIR) for functional group analysis, which revealed the presence of C-S, Si-O, and Si-O-Si vibrations in the membranes. Additionally, scanning electron microscopy (SEM) was employed to examine the surface and cross-sectional structure of the membranes. To assess membrane performance, a flux test was conducted. The membrane containing 2% nanocellulose and 1% silica exhibited the highest flux value of 21.37 L/m².h, corresponding to a permeability of 21.37 L/m².h.bar. Based on these results, the membrane with 2% nanocellulose and 1% silica is considered optimal due to its superior performance.

High-Performance Porous Supports Based on Hydroxyl-Terminated Polysulfone and CO2/CO-Selective Composite Membranes.

The scope of this work was to develop a thin-film composite (TFC) membrane for the separation of CO2/CO mixtures, which are relevant for many processes of gas processing and gasification of carbon-based feedstock. Special attention was given to the development of highly permeable porous polysulfone (PSF) supports (more than 26,000 GPU for CO2) since both the selective and support layers contribute significantly to the overall performance of the TFC membrane. The PSF porous support is widely used in commercial and lab-scale TFC membranes, and its porous structure and other exploitation parameters are set during the non-solvent-induced phase separation (NIPS) process. Since the casting solution properties (e.g., viscosity) and the interactions in a three-component system (polymer, solvent, and non-solvent) play noticeable roles in the NIPS process, polysulfone samples in a wide range of molecular weights (Mw = 76,000-122,000 g·mol-1) with terminal hydroxyl groups were synthesized for the first time. Commercial PSF with predominantly terminal chlorine groups (Ultrason® S 6010) was used as a reference. The PSF samples were characterized by NMR, DSC, and TGA methods, and the Hansen solubility parameters were calculated. It was found that increasing the ratio of terminal -OH over -Cl groups improved the "solubility" of PSF in N-methyl-2-pyrrolidone (NMP) and water. A direct dependence of the gas permeance of porous supports on the coagulation rate of the casting solution was identified for the first time. It was shown that the use of synthesized PSF (Mw = 76,000 g·mol-1, Mw/Mn = 3.0, (-OH):(-Cl) ratio of 4.7:1) enabled a porous support with a CO2 permeance of 26,700 GPU to be obtained, while the support formed from a commercial PSF Ultrason® S 6010 (Mw = 68,000 g·mol-1, Mw/Mn = 1.7, (-OH):(-Cl) ratio of 1:1.9) under the same conditions demonstrated 4300 GPU. The siloxane-based materials were used for the selective layer since the thin films based on rubbery polymers do not undergo the same accelerating physical aging as glassy polymers. Two types of materials were screened for the selective layer: synthesized polymethyltrifluoroethylacrylate siloxane-polydecylmethylsiloxane (50F3) copolymer, and polydimethylsiloxane (PDMS). 50F3 siloxane was studied for gas separation applications for the first time. It was shown that the permeance of composite membranes based on high-performance porous supports from the PSF samples synthesized was 3.5 times higher than that from similar composite membranes based on supports from a commercial Ultrason® S 6010 PSF with a permeance value of 4300 GPU for CO2. It was found that the enhanced gas permeance of composite membranes based on the highly permeable porous PSF supports developed was observed for both 50F3 polysiloxane and commercial PDMS. At the same time, the CO2/CO selectivity of the composite membranes with a 50F3-selective layer (9.1-9.3) is 1.5 times higher than that of composite membranes with a PDMS-selective layer. This makes the F-containing 50F3 polysiloxane a promising polymer for CO2/CO separation.

Effect of stretching ratio on the structure and enactment of porous PVDF-HFP hollow fiber membranes for CO2 absorption

Carbon dioxide (CO2) is responsible for increment of the Earth surface temperature and the subsequent environmental issues. In this regard, membrane contactor is one of the emerging technologies that can be applied for controlling CO2 emission. More specifically, the intrinsic structure of membrane plays an important role to govern the performance of CO2 absorption. In this study, considering stretching ratio (SR) as a key factor to affect membrane structural properties, highly porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were fabricated by a non-solvent induced phase separation method. The results showed that the membrane dimension and thickness were significantly reduced by optimizing the SR. The optimum membrane structure was found at SR of 1.5 where the mean pore size, CO2 permeance, collapsing pressure and liquid entry pressure of 0.032 μm, 3440 GPU, 550 kPa and 500 kPa were achieved, respectively. The prepared membranes showed open structure with overall porosity of more than 80%. The upgraded membrane at SR of 1.5 presented the maximum CO2 absorption flux of 9.8 × 10− 4 mol/m2 s and the minimum mass transfer resistance of 49,544 (m/s)−1. Furthermore, a stable CO2 absorption performance was achieved during 80 h continuous operation with a flux decline of only about 9%. The findings of this work demonstrated that by applying a cost-effective fabrication method, we can potentially enhance the PVDF-HFP membrane properties for CO2 adsorption without requiring an additional post-modification step.

Crystallization-driven formation of cluster assemblies on surface for super-hydrophobic poly (L-lactic acid)/ZnO composite membrane.

The poly(L-lactic acid) (PLLA)/ZnO composite membrane with cluster assemblies microstructure was constructed by a combination of non-solvent induced phase separation (NIPS) and the Breath-Figure method. In this novel method, the controllable diffusion rate between solvent and non-solvent was introduced to the system by adjusting the non-solvent solubility parameters. The humidity was adjusted to control non-solvent solubility parameters in the Breath-Figure method, which avoids the instantaneous phase separation induced by direct coagulation of water droplets. Hydrophobic modified ZnO nanoparticles were used as heterogeneous nucleation points to induce PLLA crystallization and formation of micro-nano structures. Controlling molecular chain growth with crystal nuclei as templates and constructing cluster assemblies microscopic morphology at 99% humidity, and the size of the cluster decreases gradually from 10μm to 3μm as the nanoparticles content increased up to 5wt%. The surface water contact angle could reach 153.8° with cluster morphology. In addition, the porous structure formed by the polymer-lean phase could increase the porosity to 93.1% and exhibit an excellent oil absorption capacity up to 12.64g/g. It is foreseeable that porous PLLA/ZnO composite membranes have potential applications as biodegradable oil-water separation materials.

Effects of polyvinylidene difluoride (PVDF) molecular weight on hydrophobic membranes prepared by the plasma assisted nonsolvent induced phase separation (PANIPS) method

Effects of polyvinylidene difluoride (PVDF) molecular weight on hydrophobic membranes prepared by the plasma assisted nonsolvent induced phase separation (PANIPS) method

Polypyrrole as the MOFs/polymer interfacial binder applied in mixed matrix porous separator for high temperature safe lithium-ion batteries

Uniform distribution of two-dimensional (2D) metal organic frameworks (MOFs) in polymer composites is crucial for fabricating mixed matrix porous separators (MMPS) for metal-ion (M+) batteries (MIBs). However, effectively incorporating 2D MOFs into mechanically robust and highly transportive MMPS, without agglomeration and leaching, has been challenging. Herein, we report the post-polymerization of polypyrrole (PPy) on 2D Cu-MOFs nanosheets, and their uniform distribution in the poly-(arylene ether benzimidazole) (OPBI) to prepare highly porous and mass transportive MMPS using non-solvent induced phase separation (NIPS) method for lithium ion (Li+) batteries (LIBs) applications. The polymerization of PPy not only improved the dispersibility of the Cu-MOFs nanosheets, but also acted as an interfacial binder, ensuring compatibility between the MOFs and OPBI chains. The PPy@Cu-MOFs nanosheets increased the pore size and porosity of the OPBI-based MMPS, creating wider and more uniform cross-sectional channels, thereby enhancing Li+ flux between the anode and cathode during battery charge/discharge cycles. The thermally stable, electrolyte-affinitive, and lithophilic PPy@Cu-MOFs/OPBI MMPS, when assembled in LIBs, achieved a discharge capacity of 150.2 mAh· g−1 with sustained performance over 200 cycles, showing no capacity fading even at elevated temperature. This work provides new insights into polymerizing conjugated polymer on 2D-MOFs nanosheets for improved dispersibility and uniform distribution, enabling the design of high-performance, mass transportive MMPS for safe LIBs application to meet current green energy demands.

Strength enhanced expandable polyvinyl alcohol/chitosan cryogel for non-compressible hemostasis

For penetrating and deep non-compressible bleeding, hemostatic materials need to meet the demand of easy filling and rapid expansion to close the wound. However, developing an expandable material with sufficient mechanical strength remains a challenge. This study proposed an improved non-solvent induced phase separation (NIPS) method to prepare polyvinyl alcohol/chitosan (PVA/CS) cryogel with large pore structure (70–75 um) and enhanced mechanical properties. The pore structure on the surface enables blood to quickly enter the dry and shape-fixed PVA/CS cryogel, triggering volume expansion. By regulating the hydrogen bond of PVA molecules by CS, the hydrophilia of cryogel was enhanced and the full volume recovery time of PVA/CS15% was shortened (27 ± 3 s). The aggregation of PVA molecular in solution enhances the crosslinking, endowing the prepared PVA/CS cryogel with good mechanical properties. The tensile strength of PVA/CS cryogel is up to 0.694 ± 0.044 MPa, and the compressive strength reach to 0.32 ± 0.04 MPa with 75 % compression. The good mechanical properties are beneficial for providing physical support. The preparation method does not require the introduction of toxic chemical cross-linking agents and complicated operation process, which has potential applications in non-compressible hemostasis.

Preparation of a Bi12TiO20/U6M1/PES composite membrane for rhodamine B degradation under visible-light irradiation

Being a low-energy, reusable, and environmentally friendly degradation technology, photocatalysis has excellent application prospects in textile dye wastewater degradation. In this study, we combine the advantages of photocatalysis and membrane technology to prepare photocatalytic membranes that immobilize the photocatalyst and alleviate membrane pollution. Dual-precursor graphitic carbon nitride (U6M1) was composited with Bi12TiO20 (BTO) using the annealing method to prepare a novel Δ(Z + II)-type BTO/U6M1 photocatalyst with visible-light response capacity. Subsequently, BTO/U6M1/PES composite photocatalytic membranes were fabricated using the nonsolvent-induced phase separation (NIPS) method, and the photodegradation activity of the composite membranes was executed against rhodamine B (RhB) dye. The results indicated that the composite membrane exhibiting the best photocatalytic performance achieved nearly 100 % degradation of RhB within 120 min. Furthermore, the membrane with optimal photocatalytic performance retained photocatalytic activity for five consecutive dye degradation tests, demonstrating its reusability.

Low-temperature rapid fabrication of crosslinked poly(quaterphenyl piperidine) membrane for anion exchange membrane water electrolyzers

While nonsolvent-induced phase separation (NIPS) is widely recognized as an established method for creating porous polymer membranes, this study uniquely employs a nonsolvent to produce a dense, nonporous membrane instead. Specifically, the membranes were rapidly fabricated at low temperatures using dimethyl sulfoxide (DMSO), a high-boiling-point solvent, and water as the nonsolvent. We successfully prepared a series of crosslinked poly(quaterphenyl piperidine) (PQP-BM) network membranes with high crosslinking degrees (up to 47.2 %). By combining a hydrophobic extended polyaromatic backbone with a hydrophilic piperidine-based crosslinker, we achieved distinct microphase separation, which enhanced ion transport, dimensional stability, and thermal and mechanical properties compared to the linear uncrosslinked membranes. The optimized AEM exhibited exceptional mechanical strength (tensile strength >63 MPa), high ion conductivity (151.5 mS cm⁻¹ at 80 °C), and excellent alkaline durability. In single-cell water electrolyzer tests, the PQP-BM membrane demonstrated a remarkable current density of 3.99 A cm⁻² at 2.0 V in 1 M KOH at 50 °C, outperforming the commercial FAA-3–50 membrane by 126 %. This study highlights the potential of the energy-efficient NIFF process as a scalable method for producing advanced AEMs for energy conversion applications.

Influence of different polyether sulfone substrate of thin-film composite forward osmosis membrane on neodymium rejection

Technology to treat rare earth element (REE) upstream and midstream wastewater especially acid mine drainage (AMD) is urged to be developed as it was proven current circular economy practice in downstream processes is environmentally unfriendly. This study applied forward osmosis (FO) to treat synthetic AMD containing neodymium (Nd) by using a thin-film composite (TFC) membrane as it is cheaper compared to other membrane technologies that require external pressure. Non-solvent induced phase separation (NIPS) was used to fabricate porous substrate prepared from different polyether sulfone (PES) concentrations (13 wt%, 15 wt%, 17 wt%,19 wt%) and 10 wt% PVP. Then, interfacial polymerization (IP) was done on the substrate for crosslinking of polyamide (PA) thin-film active layer. Intrinsic parameters of the fabricated TFC membranes were studied using a two-stage non-pressurized test. The occurrence of the electric double layer effect was proven in this study which was accountable for the Nd rejection together with the structure of the PA layer. TFC membrane prepared from 15 wt% PES showed the best Nd rejection efficiency with 98.28 % in ALFS orientation due to its high negative surface charge with the PA structure of leaves and nodules.

Synergy of molybdenum carbide nanosheets with PMIA separator for regulated Li+ transport in high-performance lithium-ion batteries

Separators should not only guarantee the safety performance of lithium-ion batteries (LIBs), but also enable better electrochemical performance, especially in enhancing the power density of LIBs. In this work, Mo2C/PMIA composite separator was prepared by adding molybdenum carbide (Mo2C) nanosheets to m-phenylene isophthalamide (PMIA) via a non-solvent induced phase separation process. The incorporation of Mo2C nanosheets induced a non-homogeneous interfacial modification of the PMIA separator, resulting in the increased porosity of the separator. Furthermore, the electrolyte uptake and its retention were further improved while the Li+ migration resistance was reduced, which manifested into a lower interfacial impedance (73.17 Ω). The Mo2C nanosheets significantly enhanced the adsorption energy of the Mo2C/PMIA composite separator for Li+, which in turn promoted the desolvation effects in the Li-EC of Li+ within the electrolyte and boosted the mobility of Li+. This led to a relatively high ionic conductivity of 0.57 mS cm−1 along with a Li+ mobility number of 0.77. Fast-moving Li+ reduced the concentration polarization of the LIBs, and no polarization was observed after 400 h of cycling with a lithium symmetric battery (Li||Li), suggesting that the generation of lithium dendrites was successfully suppressed using the Mo2C/PMIA composite separator. LiFePO4||Li batteries assembled with the Mo2C/PMIA composite separator demonstrated the ability to retain 90 % of their capacity throughout 150 cycles at a current density of 0.5C, achieving a discharge specific capacity of 128.5mAh g−1, which enables high-performance LIBs.

Preparation and properties of cellulose triacetate (CTA)-PVDF composite membrane with hydrophobic/hydrophilic properties for membrane distillation

The two surfaces with structural and hydrophobic differences are crucial for improving the overall membrane performance in membrane distillation (MD). In this work electrospun hydrophilic cellulose triacetate (CTA) nanofiber membrane as the support layer compounded with polyvinylidene fluoride (PVDF) liquid film followed by a nonsolvent induced phase separation process to prepare CTA-PVDF composite membranes. By changing the composition ratio of water and ethanol in coagulation bath, the structure and properties of hydrophobic PVDF functional layer can be regulated. The results proved that the composite process did not change the chemical structure of the polymer, but improved the comprehensive performance and structural stability. Morphology analysis showed that the support layer and functional layer formed a stable adhesion through swelling and other cross interpenetrating structures. The composition of the coagulation bath had a direct impact on the phase separation process and membrane structure. Within a certain range, the roughness and water contact angle (124°–135°) of the PVDF functional layer increase with the increase of ethanol content. The optimized CTA-PVDF-III showed the best separation efficiency (salt rejection of 99.6%, water flux of 19.42 kg m−2 h−1), and is expected to become a composite membrane for high-performance asymmetric MD structures.

(Invited) Rethinking Diffusion Media for Polymer Electrolyte Fuel Cells: Replacing Fluoropolymers and Engineering Microstructures

Diffusion media are performance-defining components in polymer electrolyte fuel cells, where they are responsible for multiple critical functions including providing an open porous structure for multiphase mass transport, a solid scaffold for electron and heat transport, and cushioning mechanical compression of the cell1. State-of-the-art materials are composed of an arrangement of two layers, namely a carbon fiber substrate and a microporous layer that have been engineered to sustain the complex performance requirements of the electrochemical cell. However, to date, the microstructure (e.g. pore size distribution) and surface chemistry (e.g. coating distribution, local wettability) of standard materials have not been precisely engineered which has motivated intensive research to optimize existing material sets. To improve water management, new methods aimed to introduce low capillary pressure pathways for the water to leave the cell. A non-exhaustive list of examples include the use of laser perforation2, plasma modifications3, or grafting with patterned wettability4. While these approaches have shown promising results, the addition of multiple steps onto the existing manufacturing pipelines results in higher manufacturing costs. Thus, developing methodologies that can readily fabricate precisely controlled microstructures and wetting properties from the bottom-up, while using low-cost and scalable manufacturing approaches, is an appealing avenue to further advance the technology.In this lecture, I will first review the state-of-the-art in diffusion media research and highlight key challenges. Second, I will introduce the pressing need to find alternative hydrophobic coatings to prevalent per- and polyfluoroalkyl molecules such as polytetrafluoroethylene and fluorinated ethylene propylene, as they bioaccumulate and their derivatives are damaging to living organisms5, resulting in a prospective ban6. Our group investigates the application of uniformly-distributed, thin-film coatings based on siloxanes, silanes and hydrocarbons. I will discuss the correlation between the chemical composition of these coatings, their intrinsic wetting properties, and ultimately their impact on single cell performance. Additionally, I will discuss strategies to replace fluoropolymers in conventional microporous layer inks and pastes. Third and finally, I will introduce a new approach based on non-solvent induced phase separation (NIPS) to manufacture diffusion media with controlled three-dimensional structures7. Using NIPS, we can synthesize microstructurally diverse porous media, including isoporous, pore size gradients, and structures with bimodal pore size distributions8,9. I will discuss the correlation between the diffusion media microstructure prepared with NIPS and the resulting performance in single cells. Using these methods, we aim to integrate the combined functions of carbon fiber substrates and microporous layers in a single material concept, thereby decreasing complexity and costs. References Mathias, M. F., Roth, J., Fleming, J. & Lehnert, W. Diffusion media materials and characterisation. in Handbook of Fuel Cells (John Wiley & Sons, Ltd, 2010). doi:10.1002/9780470974001.f303046.Csoklich, C., Xu, H., Marone, F., Schmidt, T. J. & Büchi, F. N. Laser Structured Gas Diffusion Layers for Improved Water Transport and Fuel Cell Performance. ACS Appl. Energy Mater. 4, 12808–12818 (2021).Zahiri, B. et al. Through-plane wettability tuning of fibrous carbon layers via O2 plasma treatment for enhanced water management. Appl. Surf. Sci. 458, 32–42 (2018).Forner-Cuenca, A. et al. Engineered Water Highways in Fuel Cells: Radiation Grafting of Gas Diffusion Layers. Adv. Mater. 27, 6317–6322 (2015).Ackerman Grunfeld, D. et al. Underestimated burden of per- and polyfluoroalkyl substances in global surface waters and groundwaters. Nat. Geosci. 17, 340–346 (2024).Tyrrell, N. D. A Proposal That Would Ban Manufacture, Supply, and Use of All Fluoropolymers and Most Fluorinated Reagents within the Entire EU. Org. Process Res. Dev. 27, 1422–1426 (2023).Non‐Solvent Induced Phase Separation Enables Designer Redox Flow Battery Electrodes - Wan - 2021 - Advanced Materials - Wiley Online Library. https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202006716.Jacquemond, R. R. et al. Microstructural engineering of high-power redox flow battery electrodes via non-solvent induced phase separation. Cell Rep. Phys. Sci. 3, 100943 (2022).Wan, C. T.-C., Jacquemond, R. R., Chiang, Y.-M., Forner-Cuenca, A. & Brushett, F. R. Engineering Redox Flow Battery Electrodes with Spatially Varying Porosity Using Non-Solvent-Induced Phase Separation. Energy Technol. 11, 2300137 (2023).

Regulatory mechanism of blending additives on interface interaction and phase separation of the heterogeneous braid-reinforced hollow fiber membranes

The exfoliation of the polymer layer from the reinforcement material is the key challenge for applying braid-reinforced hollow fiber membranes (BR HFMs). In this work, a mixed amphiphilic additive system was constructed and adopted in BR HFMs preparation by non-solvent induced phase separation (NIPS). The effect of the mixed system on the state of the casting solution and phase inversion process, the interaction between the casting solution and the braid material, together with the structure and filtration performance was studied. The role of the mixed system on the interface coordination and membrane structure formation mechanisms was elucidated. The results showed that both the composition of the mixed amphiphilic additives and the interaction time between the casting solution and braid material threw much light on the interface coordination and membrane formation. The interfacial compatibility of the casting solution and braid material was obviously improved, resulting in the enhancement of the binding force between the braid and PVDF membrane layer. The permeation flux and anti-exfoliation performance were simultaneously improved with the proper addition of the mixed amphiphilic additives. The stability of the BR HFMs was primarily testified by filtration of real sludge suspension solution with back-washing operation.

Investigating Non-Solvent Induced Phase Separation as a Fabrication Method for Lithium-Ion Battery Electrodes

Lithium-ion batteries (LIBs) are considered a key technology in the ongoing sustainable energy transition due to their importance in decarbonizing the transportation and electric power sectors. However, present embodiments cannot fully address the stringent, and often incongruous, performance, cost, and scale requirements associated with current and emerging applications, hindering widespread adoption.1 A critical barrier lies in electrode architectures capable of accommodating the high mass loadings of charge-storage materials needed to increase system-level energy densities and reduce system costs. A direct approach to maximizing electrode areal capacity and, consequently, enhancing energy densities is the use of thicker electrodes (>150 μm). While techniques such as particle alignment via magnetic fields2 and directional ice templating3 have shown promise in producing robust, thick electrodes beyond what is achievable with conventional slurry casting, these methods result in a constrained set of attainable microstructures, thus limiting design flexibility and complicating the understanding of structure-property relationships.Non-solvent induced phase separation (NIPS), a well-established membrane fabrication approach, holds potential for thick electrode production. Unlike many other processes, NIPS enables greater control over the electrode microstructure through systematic adjustment of reaction precursors and synthesis conditions, supporting the development of complex electrode designs tailored for a diversity of applications.4 Despite its promise, to date only a few studies of NIPS for LIB electrode production exist,5,6 which hampers our understanding of how design parameters impact the resulting electrode structure and performance.In this presentation, we describe how various process parameters in the NIPS fabrication procedure impact the final LIB electrode morphology, including the loading and distribution of charge-storage materials. Employing a combination of imaging and analytical techniques such as SEM-EDS, XTM, and thermogravimetric analysis, we offer insights into the critical design parameters governing the integration of active materials into the polymer matrix. Electrochemical methods including voltammetry, impedance spectroscopy, and durational cycling are utilized to evaluate performance characteristics and establish connections to the physical structure. We close with a discussion of the implementation of such electrodes into novel cell architectures and the opportunities this may enable for deploying thick electrodes. Overall, this work provides a basis for future optimization of the NIPS methodology, facilitating the advancement of thick electrodes for electrochemical energy storage and conversion.

Facile Lithium Densification Kinetics By Hyperporous/Hybrid Conductor for High-Energy-Density Lithium Metal Batteries

Lithium metal anode (LMA) emerges as a promising candidate for lithium (Li)-based battery chemistries with high-energy-density. However, inhomogeneous charge distribution from the unbalanced ion/electron transport causes dendritic Li deposition, leading to “dead Li” and parasitic reactions, particularly at high Li utilization ratios (low negative/positive ratios in full cells). Herein, we propose an innovative LMA structural model deploying a hyperporous/hybrid conductive architecture on single-walled carbon nanotube film (HCA/C), fabricated through a nonsolvent induced phase separation process. This design integrates ionic polymers with conductive carbon, offering a substantial improvement over traditional metal current collectors by reducing the weight of LMA and enabling high-energy-density batteries. The HCA/C promotes uniform lithium deposition even under rapid charging (up to 5 mA cm-2) owing to its efficient mixed ion/electron conduction pathways. Thus, the HCA/C demonstrates stable cycling for 200 cycles with a low negative/positive ratio of 1.0 when paired with a LiNi0.8Co0.1Mn0.1O2 cathode (areal capacity of 5.0 mAh cm-2). Furthermore, a stacked pouch-type full cell using HCA/C realizes a high energy density of 344 Wh kg-1 cell/951 Wh L-1 cell based on the total mass of the cell, exceeding previously reported pouch-type full cells. This work paves the way for LMA development in high-energy-density Li metal batteries.

High-performance radiative cooling PVDF-HFP film based on controllable porous structure

The preparation of porous films by nonsolvent-induced phase separation (NIPS) for efficient radiation cooling has attracted considerable attention. However, the thermodynamic uncertainty in the NIPS phase separation process may cause film formation to fail. Furthermore, the existing research on the pore size of porous films prepared by the phase separation method is inadequate. This study used the NIPS and vapor-induced phase separation (VIPS) techniques to ensure the stable formation of porous PVDF-HFP film (PPF). The pore size of the PPF was studied. The experimental results indicated that the film tended to obtain larger micropores at a concentration of 12 wt% and an immersion time of 12 h. The simulation results demonstrate that the scattering efficiency of 1.322 μm micropores is approximately three orders of magnitude higher than that of 0.077 μm nanopores. The porous film with the largest micropore exhibits high solar reflectivity (96.4 %) and long-wave infrared emissivity (95 %). It allows the sub-ambient temperature to drop by approximately 10.2 °C at a solar intensity of 514 W/m2. It retained 96.1 % reflectivity and a porous structure, after 480 h of fluorescent lamp irradiation. This work constitutes a supplement to preparing porous films by the phase separation method.