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Composite solid electrolytes (CSEs) exhibit great potential due to their advantages of both sufficient strength and high ionic conductivity. However, their interfacial impendence and ...thickness hinder potential applications. Herein, a thin CSE with good interface performance is designed through the combination of immersion precipitation and in situ polymerization. By employing a nonsolvent in immersion precipitation, a porous poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP) membrane could be rapidly created. The pores in the membrane could accommodate sufficient well-dispersed inorganic Li1.3Al0.3Ti1.7(PO4)3 (LATP) particles. Subsequent in situ polymerized 1,3‑dioxolane (PDOL) further protects LATP from reacting with lithium metal and supplies superior interfacial performance. The CSE has a thickness of ∼ 60 μm, ionic conductivity of 1.57 × 10−4 S cm−1, and oxidation stability of 5.3 V. The Li/1.25LATP-CSE/Li symmetric cell has a long cycling performance of 780 h at 0.3 mA cm−2 for 0.3 mAh cm−2. The Li/1.25LATP-CSE/LiFePO4 cell exhibits a discharge capacity of 144.6 mAh/g at 1C and a capacity retention of 97.72 % after 300 cycles. Continuous depletion of lithium salts due to the reconstruction of the solid electrolyte interface (SEI) may be responsible for battery failure. The combination of the fabrication method and failure mechanism gives new insight into designing CSEs.
Sustainable polymeric membrane fabrication aims for processes without the use of hazardous organic solvents or crosslinkers. One promising alternative method represents the fabrication of ...polyelectrolyte complex (PEC) membranes based on aqueous phase separation. We present the fabrication of PEC membranes from salt dilution induced phase separation. The complexation of the polyanion PSS and polycation PDADMAC is suppressed by an overcritical KBr concentration. The overcritical liquid polymer solution is cast and subsequently immersed in deionized water. The concentration gradient leads to salt diffusion out of, and water into the liquid polymer solution until the composition enters the demixing gap. Further salt dilution induces polyelectrolyte precipitation in the two phase region and forms the final porous PEC membrane. The presented approach shows similarities to the established non-solvent induced phase separation (NIPS), so high potential for the transfer of existing expertise. Most notably, the influence of simultaneous demixing of polyions is observed for different polyanion/polycation ratios in the liquid polymer solution. Three monomer ratios lead to membranes with different morphologies and separation properties in the range of ultrafiltration and nanofiltration. The presented method can be applied with commercially available polyelectrolytes and is easy to implement. This method is a promising approach to eliminating the use of organic solvents and realizing a sustainable alternative to the state of the art polymeric membrane fabrication processes.
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•Sustainable polymeric membrane formation via salt dilution induced phase separation.•Polyelectrolyte complex ultra- and nanofiltration membranes.•Salt dilution induced phase separation shows similarities to the established NIPS.•Demixing of polyions lead to different membrane morphologies and performances.
Polyvinylidene fluoride (PVDF) porous membrane was prepared by a two-step method of surface gelation-immersion precipitation phase inversion. Chitosan/acetic acid solution and glutaraldehyde aqueous ...solution were sequentially sprayed onto the surface of the PVDF solution film, with chitosan crosslinking and gelation occurring simultaneously on the film surface. The solution film was then immersed in a coagulation bath to obtain a modified PVDF porous membrane. The effect of the crosslinking time of chitosan and glutaraldehyde on the structure and properties of the PVDF porous membrane was discussed. The results showed that with the prolongation of crosslinking time, the surface structure of the membrane changed from a dense skin layer to a porous structure; the porosity and the mean pore size of the modified PVDF membranes increased first and then decreased, and the contact angle gradually decreased. When the crosslinking time extended to 15 min, the water flux of modified membrane (M153) reached a maximum value. BSA dynamic cyclic filtration experiment showed that the retention rate (R) of the modified membrane was significantly improved, compared to 68.3% retention rate of the blank membrane (M000), but the crosslinking time had little effect on the retention rates of the four modified membranes. The antifouling data showed that the flux recovery rate of the blank membrane was 73.0%, while the flux recovery rate of the modified membrane can reach as high as 84.40%, and the irreversible pollution rate of the blank membrane was 27.7%, while the irreversible pollution rate of the modified membrane reduced to 15.6%. These results indicated that, after surface chitosan crosslinking, the hydrophilicity and antifouling properties of PVDF membranes were improved. PRACTITIONER POINTS: Modified PVDF membranes with crosslinking CS coating were prepared by a two-step method of surface gelation-immersion precipitation phase inversion. -OH groups and -NH
groups of CS coating improve the hydrophilicity and the antifouling property of modified PVDF membranes. Modified PVDF membranes had larger mean pore size and higher porosity than unmodified membrane. Flux recovery rates of the modified membranes were higher than that of unmodified membrane. Pollution degree, reversible pollution rate, and irreversible pollution rate of modified membranes were lower than those of unmodified membrane.
Amine functionalized Multi-walled carbon nanotubes (F-MWCNTs)/polyethersulfone (PES) membranes were prepared using phase inversion induced by immersion precipitation. Crude MWCNTs were chemically ...treated using strong acids (H
2SO
4/HNO
3) and 1,3-phenylenediamine (mPDA) to produce the functional amine groups (
NH
2) on their surfaces. F-MWCNTs with different concentration were blended in the casting solution containing PES, polyvinylpyrrolidone (PVP) and dimethylacetamide (DMAC). Pure water was used as non-solvent. The FTIR spectra indicated that the amine functional groups were produced on the surface of MWCNTs. The membranes prepared with different concentrations of F-MWCNTs were characterized using contact angle, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and permeation tests. The surface hydrophilicity of membranes was significantly improved by addition of F-MWCNTs in the casting solution. An increment in the porosity, pore size and surface roughness of the membranes was observed by increasing F-MWCNTs content up to 1
wt.%. Further addition of F-MWCNTs caused a reduction in porosity and roughness of formed membrane. The membranes prepared with 0.5 and 1
wt.% of F-MWCNTs showed higher performance than neat membrane. Addition of F-MWCNTs in the casting solution improved the BSA rejection and antifouling properties of PES membrane.
► Amine functionalization of MWCNTs was carried out using strong acid and mPDA. ► Hydrophilic PES membranes were prepared by blending with F-MWCNTs via phase inversion via immersion precipitation technique. ► F-MWCNTs/PES membranes showed high antifouling properties compared to PES membrane.
The effects of hydrophilic monomers e.g. acrylic acid (AA) and 2-hydroxyethylmethacrylate (HEMA) on the morphology and performance of polyethersulfone (PES) membrane were investigated. The membranes ...were fabricated from a casting solution of PES, dimethylacetamide (DMAC), polyvinylpyrrolidone (PVP) and AA or HEMA via phase inversion induced by immersion precipitation. The mixture of water (80
vol.%) and 2-propanole (IPA, 20
vol.%) was employed as gelation media. The prepared membranes were characterized using ATR-FTIR, SEM, AFM, contact angle, viscosity measurements, ultrafiltration performance and fouling analysis. The hydrophilicity of PES membrane was improved after addition of AA and HEMA in the casting solution. The morphological studies (SEM and AFM) showed that the average sizes of membrane pores in surface and sub-layer were reduced with addition of AA and HEMA in the casting solution. Meanwhile the surface porosity was increased. The surface pore size of the untreated PES membrane was decreased from 138
nm to 45.1 and 40.6
nm with introducing 15
wt.% AA and HEMA, respectively. The experimental results showed that the pure water fluxes of membranes were declined at the presence of AA and HEMA. Moreover, the milk water permeation and protein rejection were improved at these conditions. Finally, the fouling analysis demonstrated that the membranes show fewer tendencies for fouling.
Immersion precipitation three-dimensional printing (ip3DP) and freeform polymer precipitation (FPP) are unique and versatile methods of 3D printing to fabricate 3D structures based on ...nonsolvent-induced phase separation via direct ink writing (DIW). Immersion precipitation involves complex dynamics among solvents, nonsolvents, and dissolved polymers, and the printability of 3D models in these methods requires further understanding. To this end, we characterized these two methods of 3D printing using polylactide (PLA) dissolved in dichloromethane (7.5–30% w/w) as model inks. We analyzed the rheological properties of the solutions and the effect of printing parameters on solvent–nonsolvent diffusion to achieve printability. The PLA inks exhibited shear-thinning properties, and their viscosities varied over three orders of magnitude (10–1∼102 Pa·s). A processing map was presented to understand the ideal ranges of the concentration of PLA in inks and the nozzle diameter to ensure printability, and the fabrication of complex 3D structures was fabricated with adequate applied pressure and nozzle speed. The processing map also highlighted the advantages of embedded 3D printing over solvent-cast 3D printing based on solvent evaporation. Lastly, we demonstrated that the porosity of the interface and inner structure of the printed objects was readily tailored by the concentration of the PLA and the porogen added to the ink. The methods presented here offer new perspectives to fabricate micro-to-centimeter objects of thermoplastics with nanometer-scale inner pores and provide guidelines for successful embedded 3D printing based on immersion precipitation.
The optical scattering properties of porous polyimide (PI) films were investigated for the light-extraction layer in organic light-emitting diodes (OLEDs). By adjusting mixing ratios of different ...non-solvents during the immersion precipitation process, the light scattering at the generated porous PIs can be precisely tuned. Analyzed from the final OLED devices based on prepared scattering substrates, we found that the light-output characteristics of fabricated devices are correlated with the optical scattering properties, which depends on both the size of generated pores inside porous PIs and the surface roughness at the air-interface. From the help of Mie scattering and Surface scattering simulations, a systematic approach has been performed to explain the influence of the generated micro-structure on both the optical scattering and OLED-performance.
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•Porous light-extraction layers for OLEDs with coated polyimides by immersion precipitation.•Fine control of optical scattering properties through tuning mixing ratios of two non-solvents.•Tuning capabilities of light-outcoupling efficiency and angular emission property in OLEDs.•Systematic approach to correlate optical scattering of porous films with OLED performance.•Analysis of influences of the pore-structures using both Mie scattering and surface scattering.
Cellulose triacetate/cellulose acetate (CTA/CA)-based membranes for forward osmosis (FO) were prepared by immersion precipitation. Casting composition and preparation conditions — 1,4-dioxane/acetone ...ratio, CTA/CA ratio, substrate type, casting thickness, evaporation time and annealing temperature — were tested for their effects on formation and subsequent performance of membranes. Membranes were characterized by various methods, and their performances were tested against commercially available membranes. The FO membrane prepared under optimized composition and conditions had a smooth surface and showed higher water flux and salt resistance than the commercial membranes. Annealing improved the membrane performance by removing residual additives and solvents. The computerized image processing of optical microscopy images was shown to be useful for assessing the membrane substrates.
► The first study of CTA/CA mixtures for FO membrane via immersion precipitation. ► High water flux and salt rejection were obtained by optimizing the fabrication. ► Computerized image processing was useful for assessing the membrane substrates. ► Open space ratios of the support determined the membranes' water fluxes.
A new gel polymer electrolyte (GPE) based on ethyl cellulose/poly(vinylidene fluoride) (EC/PVDF) blended polymer was prepared by immersion precipitation phase inversion. The structure of the porous ...membrane was controlled by the addition of EC. The performance of the membranes with different ratios of EC to PVDF were characterized by X-ray diffraction spectroscopy (XRD), scan electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), linear sweep voltammetry (LSV), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). The results show that as the ratio of EC to PVDF rose to 3:7 (wt.%), the membrane presented the best thermal stability. The ionic conductivity of this GPE was 1.33 mS cm−1, which was much higher than the PVDF membrane (0.69 mS cm−1) at room temperature. The electrochemical window of this GPE was established to be as high as 5.25 V (vs. Li/Li+). The Li/LiNi0.5Mn1.5O4 coin cell with this GPE displays excellent cyclic stability and rate performance at room temperature compared to PVDF membrane. This suggests that the self-supporting EC/PVDF blended GPE has a high potential for 5 V high-voltage lithium-ion batteries (LIBs).
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•Ethyl cellulose (EC) is firstly blended with PVDF to form self-supported membrane.•The crystallization and hydrophobicity of PVDF were decreased by adding EC.•The EC/PVDF membrane exhibits superior thermal stability and conductivity than PVDF.•This blended polymer electrolyte shows excellent performances in 5 V LIBs.
Poly(2,5-benzimidazole) (ABPBI) membranes were prepared by an easy and benign ‘immersion precipitation’ method; alleviating drawbacks of conventional solution casting method involving evaporation of ...the corrosive solvent. The importance of varying inherent viscosity on the properties of resulting membranes was investigated. The porous membranes formed by immersion precipitation method were analyzed for basic properties (water flux, porosity and dimensional analysis). Since the dense structure is required for their applicability for a fuel cell, through-porosity of the formed membranes was successfully eliminated using a unique shrinkage (~50%) property of ABPBI, initially, at 60 °C followed by at higher temperature. The correlation of membranes annealing temperature with the mechanical properties, phosphoric acid doping and proton conductivity was established. The present membranes exhibited high doping level (5.1 mol/RU), proton conductivity (0.083 S cm−1) and fuel cell performance. For comparison, solution casted membranes were prepared and analyzed. The OCP (0.91 V) and max power density (766 mW cm−2) are quite promising features of this new type of membranes.
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•Immersion precipitation as a method for making ABPBI based membrane for HT-PEMFC.•With unique shrinkage property of ABPBI, porous membrane transform to dense-nature.•The membranes showed highly promising acid-doping and proton conductivity.•PEMFC performance signifies importance of the immersion precipitation method.
