Solid-state Membrane Research Articles

A Super-Ionic Solid-State Block Copolymer Electrolyte.

Polymer solid-state electrolytes offer great promise for battery materials with high energy density, mechanical stability, and improved safety. However, their low ion conductivities have so far limited their potential applications. Here, it is shown for poly(ethylene oxide) block copolymers that the super-stoichiometric addition of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) as lithium salt leads to the formation of a crystalline PEO block copolymer phase with exceptionally high ion conductivities and low activation energies. The addition of LiTFSI further induces block copolymer phase transitions into bi-continuous Fddd and gyroid network morphologies, providing continuous 3D conduction pathways. Both effects lead to solid-state block copolymer electrolyte membranes with ion conductivities of up to 1·10-1Scm-1 at 90°C, decreasing only moderately to 4·10-2Scm-1 at room temperature, and to >1·10-3Scm-1 at -20°C, corresponding to activation energies as low as 0.19eV. The co-crystallization of PEO and LiTFSI with ether and carbonate solvents is observed to play a key role to realize a super-ionic conduction mechanism. The discovery of PEO super-ionic conductivity at high lithium concentrations opens a new pathway for fabrication of solid polymer electrolyte membranes with sufficiently high ion conductivities over a broad temperature range with widespread applications in electrical devices.

In situ generation of (sub) nanometer pores in MoS2 membranes for ion-selective transport

Ion selective membranes are fundamental components of biological, energy, and computing systems. The fabrication of solid-state ultrathin membranes that can separate ions of similar size and the same charge with both high selectivity and permeance remains a challenge, however. Here, we present a method, utilizing the application of a remote electric field, to fabricate a high-density of (sub)nm pores in situ. This method takes advantage of the grain boundaries in few-layer polycrystalline MoS2 to enable the synthesis of nanoporous membranes with average pore size tunable from <1 to ~4 nm in diameter (with in situ pore expansion resolution of ~0.2 nm2 s−1). These membranes demonstrate selective transport of monovalent ions (K+, Na+ and Li+) as well as divalent ions (Mg2+ and Ca2+), outperforming existing two-dimensional material nanoporous membranes that display similar total permeance. We investigate the mechanism of selectivity using molecular dynamics simulations and unveil that the interactions between cations and the sluggish water confined to the pore, as well as cation-anion interactions, result in the different transport behaviors observed between ions.

Ionic current blockade in a nanopore due to an ellipsoidal particle.

Nanopores in solid-state membranes have been used to detect, identify, filter, and characterize nanoparticles and biological molecules. In this work, we simulate an ionic flow through a nanopore while an ellipsoidal nanoparticle translocates through a pore. We numerically solve the Poisson-Nernst-Planck equations to obtain the ionic current values for different aspect ratios, sizes, and orientations of a translocating particle. By extending the existing theoretical model for the ionic current in the nanopore to the particles of ellipsoidal shape, we propose semiempirical fitting formulas which describe our computed data within 5% accuracy. We also demonstrate how the derived formulas can be used to identify the dimensions of nanoparticles from the available experimental data which may have useful applications in bionanotechnology.

Direct Non-Oxidative Methane Conversion and Hydrogen Co-Production in a Proton Conducting Membrane Reactor

Direct Non-oxidation Methane Conversion (DMNC) has been recognized a promising technology for the upgrading of cheap and abundant methane to higher hydrocarbons (C2+) and H2, but this technology has not been commercialized yet because of the low methane equilibrium conversion and severe carbon deposition.1-3 Here, we present our effort to develop a proton conducting membrane reactor (SrCe0.7Zr0.2Eu0.1O3- ⴃ) combined with the catalysts (Fe©SiO2) to circumvent the equilibrium limitations of the DMNC reaction and solve the coking (i.e., solid carbon deposition) problem. By coupling the Fe©SiO2 catalysts with H2 permeable membrane reactor, part of produced H2 during the catalytic conversion can be extracted from the effluent gas, which not only provides a one-step hydrogen production without additional separation process, but also shifts the equilibrium of the reaction to the product side and achieves an improved methane conversion and higher C2+ yield when compared to the traditional fixed-bed reactor. In addition, an air sweep outside the reactor results in O-permeation into catalyst to oxidize any deposited carbon to CO thus preventing coking.The membranes were fabricated using tape casting of the support layer followed by dip coating process to form the dense membrane layer. Using this method, we obtained 25 µm for the thickness of the dense layer and around 700 µm for the thickness of the support layer (see Fig. 1a and 1b). The catalyst was synthesized by a simple sol-gel method followed by fusing process, and then was crushed into 40-80 mesh and loaded inside of membrane reactor to test.The performance metrics include methane conversion, selectivity, and product yield. Our membrane reactor achieved single-pass methane conversion of 17.5%, and a C2+ yield of 15% (see Fig. 1c) at 1323K.Finally, our membrane reactors were stable for over 350 hours, which, along with the aforementioned performance metrics, constitutes a major advance in the development of commercial DMNC technology. References Guo, X.; Fang, G.; Li, G.; Ma, H.; Fan, H.; Yu, L.; Ma, C.; Wu, X.; Deng, D.; Wei, M.; Tan, D.; Si, R.; Zhang, S.; Li, J.; Sun, L.; Tang, Z.; Pan, X.; Bao, X., Direct Nonoxidative Conversion of Methane to Ethylene, Aromatics, and Hydrogen. Science 2014, 344 (6184), 616-619.Thyssen, V. V.; Vilela, V. B.; de Florio, D. Z.; Ferlauto, A. S.; Fonseca, F. C., Direct Conversion of Methane to C2 Hydrocarbons in Solid-State Membrane Reactors at High Temperatures. Chemical Reviews 2022, 122 (3), 3966-3995.Sakbodin, M.; Schulman, E.; Cheng, S.; Huang, Y.-L.; Pan, Y.; Albertus, P.; Wachsman, E. D.; Liu, D., Direct Nonoxidative Methane Conversion in an Autothermal Hydrogen-Permeable Membrane Reactor. Advanced Energy Materials 2021, 11 (46), 2102782. Figure 1

Development of sensitive biomass xylan-based carbon dots fluorescence sensor for quantification detection Cu2+ in real water and soil

Copper ions (Cu2+) pose significant risks to both human health and the environment as they tend to accumulate in soil and water. To address this issue, an innovative method using biomass-derived fluorescent carbon dots (D-CDs) synthesized via a hydrothermal process, with xylan serving as the carbon source was developed. D-CDs solution exhibited remarkable sensitivity and selectivity as a fluorescence sensor for Cu2+, boasting a low detection threshold of 0.64 μM. In order to facilitate real-time monitoring of Cu2+, solid-state fluorescent nanofiber membrane (NFD-CDs) through electrospinning was engineered. Additionally, D-CDs demonstrated successful Cu2+ detection in various real water samples, including those sourced from Xuanwu Lake, the Yangtze River, tap water, and bottled water, with accurate recovery rates observed. As a result, this research introduces a dual-mode analytical system for onsite detection of Cu2+ in real scenarios. By harnessing biomass-derived fluorescent CDs materials and solid-state fluorescence sensors, this approach offers a promising solution for addressing the challenges associated with Cu2+ contamination.

Development of Voltammetry Analysis Method of Iron Metal Ions by Solid-State Membrane with Carbon Nanotube

This work developed a selectively modified electrode for measuring the Fe(II) ions in continuous integration using voltammetry techniques. The study assessed various aspects, such as linearity, scan rate, repeatability, and real sample analysis. The experiment is performed using differential pulse voltammetry (DPV). The findings of the study indicated that the voltammetry method exhibited a regression line of y = 36.507 ln(x) + 990.73, with a correlation value of 0.9627, with an optimum scan rate of 20 mV/s and good repeatability over five times measurement. On the other hand, when comparing the results using the UV-Vis spectrophotometric technique, the regression equation was found to be y = 0.20438x − 0.06987, with a correlation value of 0.99583. Notably, the voltammetry measurement outperformed the UV-Vis method since it allowed analysis of Fe(II) at concentrations up to 6.35 × 10−4 ppm (or 1.00 × 10−11 M), while the UV-vis measurement could only analyze up to 1.5 ppm (or 2.36 × 10−5 M). Consequently, the developed technique proves to be superior to the other methods for the analysis of Fe(II).

Jet-Printable, Low-Melting-Temperature Ga-xSn Eutectic Composites: Application in All-Solid-State Batteries.

Low-melting-point Ga-xSn eutectic composites and natural silicate mineral powders were used as the electrode and solid-state electrolyte, respectively, in all-solid-state batteries for green energy storage systems. The influences of the Sn content in the Ga-xSn composite electrode on the electrochemical performance of the batteries were evaluated, and liquid composites with a Sn concentration of up to 30 wt.% demonstrated suitability for electrode fabrication through dip coating. Sodium-enriched silicate was synthesized to serve as the solid-state electrolyte membrane because of the abundance of water molecules in its interlayer structure, enabling ion exchange. The battery capacity increased with the Sn content of the Ga-xSn anode. The formation of intermetallic compounds and oxides (CuGa2, Ga2O3, Cu6Sn5, and SnO2) resulted in a high charge-discharge capacity and stability. The Ga-Sn composite electrode for all-solid-state batteries exhibits a satisfiable capacity and stability and shows potential for jet-printed electrode applications.

Performance study of sodium alginate (SA) with lithium chloride (LiCl)-based solid-state membrane as an electrolyte in electrochemical device application

Performance study of sodium alginate (SA) with lithium chloride (LiCl)-based solid-state membrane as an electrolyte in electrochemical device application

Building continuous Li-ion transport channels from cathode to anode in solid-state lithium-metal batteries

Homogeneous Li+ transport channels through the electric core were built by surface modifications of both the solid-state electrolyte membrane and the binder phase in the cathode, thus improving the performance of solid-state lithium batteries.

Fluorescence methods to probe mass transport and sensing in solid-state nanoporous membranes

This article aims to guide the reader for (red gear) selecting the right nanoporous membrane, and (blue gear) study its nanopore activities by most suitable luminescence method towards (yellow gear) the high-performance membrane application.

A nanocrystal garnet skeleton-derived high-performance composite solid-state electrolyte membrane

Composite solid-state electrolytes (SSEs) can improve the flexibility of the oxide SSEs to decrease the interfacial resistance between the electrolytes and the electrodes. However, the ceramic nanofillers within the composite SSEs suffer from the agglomeration at high concentrations, decreasing the ion conductivities. In this study, a continuous nanocrystal Li6.5La3Zr1.5Ta0.5O12 (LLZTO) skeleton is prepared by the ultrafast high-temperature sintering (UHS) together with tape-casting. Due to the short sintering time of ∼5 s from precursors, the LLZTO grains are restrained to ∼300 nm with limited Li loss. Even with trace solvent (3 wt%), the composite SSE membrane exhibits an ion conductivity of 5 × 10−4 S⋅cm−1, ∼50 times higher than the DOL electrolyte (1 × 10−5 S⋅cm−1, 8 wt% solvent), which further proves the high Li-ion conductivity of the nanocrystal LLZTO skeleton. The composite SSE membrane exhibits a critical current density of 3.4 mA⋅cm−2, among the highest reported values for ceramic-polymer SSEs. The Li/composite SSEs/Li symmetric cells can cycle ∼ 120 h at the current density from 0.2 to 0.4 mA⋅cm−2. The LiFePO4/LLZTO-PEGDA composite SSEs/Li full cell exhibits a high specific discharge capacity of ∼150 mAh⋅g−1 for ∼50 cycles with a Coulombic efficiency of ∼97%. To explore the processability of the membrane with large size, we also demonstrate a pouch cell (2 cm × 5 cm) with a high specific capacity of ∼150 mAh⋅g−1 for ∼25 cycles and a capacity retention of ∼94.5%. This work paves a new way to manufacture the nanocrystal ceramic SSE skeleton for high energy density all-solid-state batteries.

Versatile Mixed Ionic-Electronic Conducting Binders for High-Power, High-Energy Batteries

The increasingly extensive use of Lithium-Ion Batteries (LIBs) requires further optimization of the devices to make use of their maximum practical specific capacity. Although the binder occupies a small fraction of the electrode mass, it is one of the most crucial components to achieve improved cell performance and cycle life. Conducting polymers such as PEDOT:PSS have been already studied as binders for high-performance lithium-ion batteries (LIBs) but without addressing the structure-property relationships of the binder in the electrode. Herein, we develop mixed ionic-electronic conducting (MIEC) binders based on PEDOT:PSS (PPSS) and PEDOT:PDADMA-TFSI (PPTFSI) for Li-ion cathodes and we compare their performances with conventional formulations containing PVDF binder in Li||LFP cells. Furthermore, the influence of electrode formulations, including addition of conducting carbon (C), to balance the required porosity; and the Organic Ionic Plastic Cristal (OIPC) N-ethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide) (C2mpyrTFSI, O), to promote a synergistic effect of ionic and electronic conductivity enhancement; are analyzed. Finally, the versatility of these proposed binders is demonstrated with graphite||LFP full cells, high-voltage active material (NMC 111) as well as different electrolyte types (from liquid 1M LiTFSI in DOL/DME and ionic liquid based, to solid state membranes) showing the same trends, with improved performances in comparison with conventional formulations.

A Summary of Recent Developments in Potentiometric Sensor Arrays

With upgrades in as far as possible and selectivity of ISEs, the presentation of new materials, new detecting ideas (from regular potentiometric to dynamic electrochemistry draws near), and more profound hypothetical getting it and displaying of the potentiometric reactions of ISEs, potentiometric in light of particle specific cathodes (ISEs) has encountered a renaissance. Ion sensors based on solid-state or polymeric membranes are currently available and can be used in sensor array formats for a variety of analytical applications. Coated wire electrodes (CWE), ion-sensitive field-effect transistors (ISFETs), and light-addressable potentiometric sensors (LAPS) are just a few of the strategies that have been developed to construct and use potentiometric sensor arrays based on various transduction principles. This review aims to provide a critical overview of these strategies. After reading recent papers on the development and applications of potentiometric sensor arrays, several issues and trends have been identified.

Sintering Aid Strategy for Promoting Oxygen Reduction Reaction on High-Performance Double-Layer LaNi0.6Fe0.4O3-δ Composite Electrode for Devices Based on Solid-State Membranes.

Strontium and cobalt-free LaNi0.6Fe0.4O3-δ is considered one of the most promising electrodes for solid-state electrochemical devices. LaNi0.6Fe0.4O3-δ has high electrical conductivity, a suitable thermal expansion coefficient, satisfactory tolerance to chromium poisoning, and chemical compatibility with zirconia-based electrolytes. The disadvantage of LaNi0.6Fe0.4O3-δ is its low oxygen-ion conductivity. In order to increase the oxygen-ion conductivity, a complex oxide based on a doped ceria is added to the LaNi0.6Fe0.4O3-δ. However, this leads to a decrease in the conductivity of the electrode. In this case, a two-layer electrode with a functional composite layer and a collector layer with the addition of sintering additives should be used. In this study, the effect of sintering additives (Bi0.75Y0.25O2-δ and CuO) in the collector layer on the performance of LaNi0.6Fe0.4O3-δ-based highly active electrodes in contact with the most common solid-state membranes (Zr0.84Sc0.16O2-δ, Ce0.8Sm0.2O2-δ, La0.85Sr0.15Ga0.85Mg0.15O3-δ, La10(SiO4)6O3-δ, and BaCe0.89Gd0.1Cu0.01O3-δ) was investigated. It was shown that LaNi0.6Fe0.4O3-δ has good chemical compatibility with the abovementioned membranes. The best electrochemical activity (polarization resistance about 0.02 Ohm cm2 at 800 °C) was obtained for the electrode with 5 wt.% Bi0.75Y0.25O1.5 and 2 wt.% CuO in the collector layer.

Multilayer structure solid-state electrolyte composite membranes for long-life quasi-solid-state battery

To reduce the impedance of the interface between solid electrolytes and electrodes and improve the interfacial stability, the liquid electrolyte (LE) is added between solid-state electrolytes and electrodes. We design LE containing different lithium salts, additives and a solid-state electrolyte membrane containing polyvinylidene fluoride (PVDF), Li1.3Al0.3Ti1.7(PO4)3 (LATP) and polypropylene membrane (PP) (LATP membrane), and systematically investigate the interfacial wettability, stability and safety through contact angle analysis, interfacial impedance measurements, and linear scanning voltammetry. The results show that the LE containing 1 M lithium hexafluorophosphate (LiPF6) salt, 1.3-propane sultone (1.3-PS) additive, adiponitrile, fluoroethylene carbonate (FEC), and that containing 0.575 M lithium bis(trifluoromethane sulfonimide) (LiTFSI)/0.575 M LiPF6 salt, trimethyl phosphate, FEC, and PS exhibit superior performance. The interfacial impedance of the Li|LE-LATP membrane-LE|Li coin cell is only ∼50 Ω. The LiNi0.6Co0.2Mn0.2O2 (NCM622)|LE-LATP membrane-LE|Si/C coin cell exhibits an initial specific discharge capacity of ∼163 mAh g−1 at 0.5 C and 25 °C, and the capacity retention rate is ∼87% after 100 cycles. Furthermore, the 5 Ah NCM622|LE–LATP membrane–LE|Si/C pouch battery exhibits a capacity retention rate of> 90% after 400 cycles at 25 °C and 1 C.

Solid-state polymer magnesium supercapacitor

The present article focuses on the development of a highly ion-conductive, solvent-free, solid-state polymer electrolyte membrane (PEM) via photopolymerization of polyethylene glycol diacrylate (PEGDA) network from its homogeneous melt mixtures containing succinonitrile (SCN) plasticizer and magnesium bis(trifluoromethane sulfonyl) imide Mg(TFSI)2 salt. The above solid-state Mg-PEM exhibits a Helmholtz electric double-layer capacitor (EDLC) behavior in its supercapacitive symmetric carbonaceous electrode configuration. The electrochemical stability for this PEM membrane (20/40/40 PEGDA/SCN/Mg (TFSI)2) was found to be approximately 3 V from linear sweep voltammetry with a specific capacitance of about 44 F/g from cyclic voltammetry and an energy density of approximately 17 Wh/kg in the 0–2 V range from the constant current density (CCD) experiment. Of particular interest is its excellent capacity retention of over 11,200 cycles, thus tested with the Coulombic efficiency of over 87%. Moreover, the energy density after extensive cycling for 11,200 has increased to approximately 56 Wh/kg at 10 mV/s in the potential range of 0–3 V relative to 17 Wh/kg in the potential range of 0–2 V at the same scan rate, attesting the excellent electrochemical stability and long life of the present Mg-PEM supercapacitor.

Review of technologies for carbon monoxide recovery from nitrogen- containing industrial streams

Carbon monoxide (CO) is an important gas required for various industrial processes. Whether produced directly from syngas or as part of by-product gas streams, valorization of CO streams will play an important role in the decarbonization of industry. CO is often generated in mixtures with other gases such as H2, CO2, CH4, and N2 and therefore separation of CO from the other gases is required. In particular, separation of CO from N2 is difficult given their similar molecular properties. This paper summarizes the current state of knowledge on the four processes for separation of CO from gas mixtures: cryogenic purification, absorption, adsorption and membrane separation. Particular emphasis is placed on technical processes for industrial applications and separation of N2 and CO. Cryogenic processes are not suitable for separation of CO from N2. Absorption developments focus on the use of ionic liquids to replace solvents, with promising progress being made in the field of CO solubility in ionic liquids. Advancements in adsorption processes have focused on the development of new materials however future work is required to develop materials that do not require vacuum regeneration. Membrane processes are most promising in the form of solid state and mixed matrix membranes. In general, there is limited development beyond lab scale for new advancements in CO separation from gas streams. This highlights an opportunity and need to investigate and develop beyond state-of-the-art processes for CO separation at industrial scale, especially for separation of CO from N2.

Thin, Flexible, and High-Performance Solid-State Polymer Electrolyte Membranes for Li–O2 Batteries

A solid-state lithium–oxygen battery (SSLOB) has become more attractive as a next-generation energy storage device, with the expectation of long-term safe and wide applications with superior energy density. However, the development of a thin and flexible solid-state electrolyte having good interfacial and chemical stability toward lithium metal and/or oxygen has been a big challenge. Accordingly, a solid-state composite electrolyte membrane has been prepared by impregnating polyethylene glycol (PEG) and succinonitrile plastic crystals (SNPCs) along with lithium bromide redox mediator into a porous polytetrafluoroethylene (PTFE) substrate for application in a SSLOB. The prepared thin electrolyte membrane (23 μm) displays a high ionic conductivity of 1.03 mS cm–1, a tensile strength of 46.5 MPa, and elongation at a break of 100% with excellent flexibility. It also exhibits a wide electrochemical stability window (∼4.9 V) and low interfacial resistance of 80 Ω cm2. The SSLOB cell assembled with the synthesized XPEG/SNPC@PTFE electrolyte membrane shows excellent electrochemical stability during 277 cycles, maintaining a 1000 mAh g–1 discharge capacity. The low terminal voltage difference between the charge and discharge processes of these polymer electrolyte membranes (∼0.65 V) compared to those of liquid or other polymer electrolytes (∼1.4 V) is also an advantageous characteristic for their application in high-performance SSLOBs.

Porous inorganic filler Li4.7Ag1.63GeS4.8 in PEO electrolyte effectively inhibits Li dendrites for all-solid-state Li metal batteries

The newly created porous inorganic particles Li4.7Ag1.63GeS4.8 as filler are added into poly (ethylene oxide) (PEO) with LiTFSI salt, which greatly improves the electrochemical stability of solid-state PEO-based electrolytes against Li metal in a working battery. Due to many pores and channels in the filler, Li dendrites would grow along these channels thereby effectively inhibiting their fast spread in PEO matrix and retarding the short circuit on account of the penetration of Li dendrite. The Li+ conductivity of this solid-state electrolyte membrane could be 1.36 × 10-4 S/cm at 40 °C. The fabricated symmetrical Li metal cells could cycle above 550 h at 0.05 mA/cm2 and corresponding LiFePO4/Li all-solid-state cells have an excellent cycling stability of 160.65 mAh g-1 specific capacity after 200 cycles with 99.93% columbic efficiency at 50 °C environment.

Amino-functionalized graphene oxide membranes for efficient separation of Sr2+ ions

Graphene oxide (GO) membranes were integrated with diverse nitrogen functional groups by subjecting to ammonia (NH3) vapours and evaluated for resultant changes in their chemical functioning and strontium (Sr) adsorption performance. Exposure to NH3 vapours amends the functional groups of GO, introduces amine, amide, ammonium functionalities and generates abundant sites prone to react with Sr2+ ions. The extent of GO restructuring and repercussions on Sr adsorption behaviour were examined using different GO precursors, NH3 treatment methods, membranes with varying GO mass and other nitrogen reagents namely, tri-isooctyl amine, pyridine, N,N-dimethyl acetamide. Nitrogen group functionalization enhances the Sr adsorption capacity of GO membranes nearly by two times, irrespective of the NH3 exposure duration and nature of precursor GO membranes. These NH3 subjected GO membranes displayed optimum Sr adsorption performance of ~475 mg/g, reusable at least for nine filtration cycles and importantly, capable of discharging 35–60 % of adsorbed Sr. The N-group supported Sr separation demonstrated in the present work is an energy efficient solid state membrane based procedure, which also lays a road map for development of amine, amide, ammonium functionalized GO layers and provides flexible platform for separation of all those toxic elements displaying affinity to complex with N-groups.