Ionic Conductivity Research Articles

Highly Efficient and Durable Water Electrolysis at High KOH Concentration Enabled by Cationic Group-Free Ion Solvating Membranes in Free-standing Gel Form.

The degradation of fixed cationic groups in most anion exchange membranes (AEMs) under alkaline environments limits their durability for alkaline water electrolysis (AWE). Ion-solvating membranes (ISMs) have emerged as a promising alternative to address this issue. Herein, a cationic group-free ion solvating membrane in a free-standing gel form (ISM-PBI-FG) is presented, created through a sol-to-gel transformation process followed by KOH imbibing. This approach yields a 3D porous microstructure composed of entangled polybenzimidazole (PBI) nanofibrils, achieving 89% porosity, which enables ultrahigh alkali uptake (346% in 6 M KOH) and exceptional ionic conductivity (763 mS cm-1 at 80 °C). The absence of cationic groups avoids the attack by OH-, thus ensures good alkaline stability with a conductivity retention rate of 91.6% over a 3120 h ex situ test in 6 M KOH. The resulting membrane delivered outstanding AWE performance with current densities of 5.5 A cm-2 using platinum-group-metal (PGM) catalysts and 2.2 A cm-2 using PGM-free catalysts at 2.0 V. Notably, the in situ electrolyzer device based on ISM-PBI-FG offers extensive operational flexibility ranging from 40-100 °C and demonstrates record durability in concentrated alkaline conditions, with a voltage decay rate of only 23.5µVh-1, outperforming most reported AEMs and ISMs.

Li-ion batteries with poly[poly(ethylene glycol) methyl ether methacrylate]-grafted oxidized starch solid and gel polymer electrolytes

Polymer electrolytes are considered in lithium-ion batteries because of their high safety and properties such as flexibility, easy moldability, etc. Starch is one of these polymers from renewable resources. Considering the semi-crystal structure of starch and ion conduction in amorphous phase, herein starch is oxidized and then modified with poly[poly(ethylene glycol) methyl ether methacrylate]. Solid polymer electrolytes (SPEs) are prepared by dissolution of lithium salt within polymer while gel polymer electrolytes (GPEs) as crosslinked structures are swollen in lithium salt solution. After validation of successful syntheses, all SPEs and GPEs with different oxidation state and various PEGMA/oxidized starch are evaluated in Li-ion battery performance. The synthesized GPEs and SPEs show the highest ionic conductivity of 5.5 × 10−3 and 2.19 × 10⁻⁴ S cm⁻1, respectively at room temperature. Lithium ion transfer number (t+) of 0.6–0.9 and electrochemical stability window of 4.4–4.9 V are obtained for SPEs and GPEs. The discharge capacity is ∼180 mAh g−1 at 0.2 C with capacity retention of 75 % after 100 cycles.

Pitch-derived C coated three-dimensional CNTs/reduced graphene oxide microsphere encapsulating Si nanoparticles as anodes for lithium-ion batteries

This study presents an innovative strategy for synthesizing a sophisticated three-dimensional conductive framework that contains well-dispersed silicon nanoparticles. This framework features silicon nanoparticles encapsulated by a composite of one-dimensional carbon nanotubes (CNTs), two-dimensional reduced graphene oxide (rGO), and amorphous carbon, all of which are further coated with a pitch-derived carbon (PDC) layer. This unique nanostructured anode was prepared from a one-pot spray drying process, heat-treatment and subsequent pitch-derived carbon coating. Combining 1D CNTs and 2D rGO nanosheets creates a 3D conductive network that can facilitate the electrochemical reaction kinetics. Furthermore, pitch-derived carbon coating at the interior and on the surface densified the electrode, ensuring both lithium-ion and electron transport and enhancing the Coulombic efficiency. Therefore, the composite plays the role of an effective mixed ionic and electronic conductor (MIEC), which can highly enhance the electrochemical performance of Si-based anode. Also, the volume expansion issues of silicon materials could be resolved by compositing with 3D conductive carbon matrix and reinforcing the structural robustness by coating with PDC layer, which could effectively alleviate the stress occurring from repetitive cycling. When used as the anode in lithium-ion batteries, the microspheres exhibited exceptional initial discharge/charge capacities of 3814/2791 mA h g–1 at 0.1 A g−1 with high Coulombic efficiency of 73.2 %, and demonstrated highly stable cycle performance, delivering a discharge capacity of 947 mA h g−1 after 350 cycles at a current density of 1.0 A g−1.

A PET-enhanced PEO-ionic liquid-based gel polymer electrolyte for solid state lithium metal batteries

Gel polymer electrolytes (GPEs) are attractive for their promising prospect in lithium metal batteries (LMBs) owing to their outstanding thermal stability and remarkable electrochemical performance. Nevertheless, the practical application of traditional GPEs is significantly impeded by their limited mechanical strength. In order to address this issue, this study introduces an ultrathin and mechanically-strong poly(ethylene terephthalate) (PET) nonwoven fabric (PET-NW) as a rigid support layer for the GPEs composed of poly (ethylene oxide) (PEO) and ionic liquid (IL) EMIM-TFSI. The resulting PEO-IL/PET-NW-based GPE (NW GPE) demonstrates an excellent lithium ionic conductivity of 4.21 × 10−4 S cm−1, a lithium ion transference number of 0.20, and an ultrahigh mechanical strength of 53.2 MPa. These characteristics collectively contribute to the suppression of lithium dendrites growth and improved electrochemical performance of Li|NW GPE|LiFePO4 full cells which exhibit enhanced rate capability and cycling stability in comparison with Li|GPE-I30|LiFePO4 full cells. The employment of PET-NW in the fabrication of GPEs can pave a viable way for significant advancements in high-performance solid state LMBs for various practical applications.

Strain-Enhanced Low-Temperature High Ionic Conductivity in Perovskite Nanopillar-Array Films.

Solid oxide ionic conductors with high ionic conductivity are highly desired for oxide-based electrochemical and energy devices, such as solid oxide fuel cells. However, achieving high ionic conductivity at low temperatures, particularly for practical out-of-plane transport applications, remains a challenge. In this study, leveraging the emergent interphase strain methodology, we achieve an exceptional low-temperature out-of-plane ionic conductivity in Na0.5Bi0.5TiO3 (NBT)-MgO nanopillar-array films. This ionic conductivity (0.003 S cm-1 at 400 °C) is over one order of magnitude higher than that of the pure NBT films and surpasses all conventional intermediate-temperature ionic conductors. Combining atomic-scale electron microscopy studies and first-principles calculations, we attribute this enhanced conductivity to the well-defined periodic alignment of NBT and MgO nanopillars, where the interphase tensile strain reaches as large as +2%. This strain expands the c-lattice and weakens the oxygen bonding, reducing oxygen vacancy formation and migration energy. Moreover, the interphase strain greatly enhances the stability of NBT up to 600 °C, well above the bulk transition temperature of 320 °C. On this basis, we clarify the oxygen migration path and establish an unambiguous strain-structure-ionic conductivity relationship. Our results demonstrate new possibilities for designing applicable high-performance ionic conductors through strain engineering.

Implementation of phosphonium salt for high-performance supercapacitors from room to ultra-low temperature conditions

Conventional supercapacitors encounter limitations in operating voltage and performance at low temperatures due to poor ionic conductivity and diminished interfacial dynamics in electrolytes. In this study, we synthesized the phosphonium salt 5-phosphinaspiro[4.4] nonane tetrafluoroborate (PSNBF4) for the first time. We extensively characterized the physical and electrochemical properties of PSNBF4 in acetonitrile (AN) and propionitrile (PN) as electrolytes, assessing their performance in supercapacitors at room temperature and − 40 °C. The results demonstrate PSNBF4 electrolytes exhibit high solubility, outstanding ionic conductivity (1 M PSNBF4/AN: 49.8 mS cm−1; 1 M PSNBF4/PN: 27.5 mS cm−1), and high electrochemical stability, contributing to good capacitance retention after 500 h of floating tests at 25 °C. Supercapacitors using PSNBF4/AN retained 78 % of their capacitance at 3.1 V, whereas those with PSNBF4/PN maintained 68 % at 3.2 V. Impressively, these supercapacitors performed exceptionally well at −40 °C, displaying excellent cycle stability and high capacitance retention at elevated voltages. Supercapacitors with PSNBF4/AN retain 96.6 % of their capacitance at 3.2 V, while PSNBF4/PN retained 93.4 % of their capacitance at 3.4 V after floating for 500 h. These results demonstrate PSNBF4-based supercapacitors can operate effectively at high voltages in both room and extremely low temperatures, addressing a significant challenge in commercial supercapacitor applications.

Dual influence of protonation on Li-ion transport in garnet solid electrolytes: A first-principles study

Garnet-type cubic Al-doped Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for all-solid-state Li-ion batteries because of its excellent ionic conductivity and stability against Li metal. However, its sensitivity against moisture poses a significant challenge, as LLZO undergoes protonation upon exposure to water, which has been experimentally observed to reduce Li-ion conductivity. Despite this, the exact impact of protonation-induced structural changes and the role of protons in Li-ion transport within LLZO remain unclear. A thorough understanding of these mechanisms is crucial for enhancing the performance of LLZO as a solid electrolyte. In this study, we employed density functional theory (DFT) and DFT-based molecular dynamics (DFT-MD) simulations to investigate the effect of protonation on the structure, Li-ion transport, and proton dynamics in LLZO. Our results demonstrate that protonation induces a phase transition from the centrosymmetric Ia3‾d to a distorted non-centrosymmetric I4‾3d symmetry, concomitantly reducing the Li-ion conductivity, consistent with experimental observations. Furthermore, we identify two competing effects of protonation on Li-ion transport: protons tend to occupy octahedral sites, which trap Li-ions in more stable tetrahedral sites, thereby impeding their mobility. Conversely, proton insertion enlarges the bottlenecks along Li-ion diffusion pathways from a range of 1.78–1.90 Å to 1.80–1.92 Å, potentially lowering the diffusion barrier for Li transport. Therefore, protonation introduces both inhibitory and facilitating factors for Li-ion transport. Additionally, the reduction in Li-ion concentration due to protonation further diminishes the overall ionic conductivity of LLZO.

Imidazolium‐Quaternized Poly(2,6‐Dimethyl‐1,4‐Phenylene Oxide)/Zeolitic Imidazolate Framework‐67 (ImPPOZIF‐67) Composite Membranes for Methanol Fuel Cells

ABSTRACTA membrane is the powerhouse of a fuel cell, and it is responsible for transport of ions from anode to cathode, thereby producing electricity in the process. In this work, a series of anion exchange membranes based on imidazolium‐quaternized poly(2,6‐dimethyl‐1,4‐phenylene oxide) (ImPPO) functionalized with different wt.% of zeolitic imidazolate framework‐67(ZIF‐67) (1%, 3%, and 5%) were fabricated and evaluated for application in methanol fuel cells. The AEMs had a contact angle in the range of 59.6°–74.6°, water uptake in the range of 29.4%–69.7% at 25°C, 31.2%–79.5% at 60°C, and 51.6%–86.5% at 80°C. Ion exchange capacity (IEC) ranges from 0.66 mmol/g to 1.12 mmol/g, and ion conductivity (IC) from 1.39 mS/cm to 3.11 mS/cm. The best‐performing membrane, ImPPO3%ZIF‐67, shows IEC of 1.12 mmol/g, IC of 3.11 mS/cm, a slight conductivity loss of 35.4% after 120 h in 2 M KOH, and a peak power density of 196.8 mW/cm2.

Dissecting current rectification through asymmetric nanopores

Rectification, the tendency of bidirectional ionic conductors to favor ion flow in a specific direction, is an intrinsic property of many ion channels and synthetic nanopores. Despite its frequent occurrence in ion channels and its phenomenological explanation using Eyring’s rate theory, a quantitative relationship between the rectified current and the underlying ion-specific and voltage-dependent free energy profile has been lacking. In this study, we designed nanopores in which potassium and chloride current rectification can be manipulated by altering the electrostatic pore polarity. Using molecular dynamics-based free energy simulations, we quantified voltage-dependent changes of free energy barriers in six ion-nanopore systems. Our results illustrate how the energy barriers for inward and outward fluxes become unequal in the presence of an electromotive driving force, leading to varying degrees of rectification for cation and anion currents. By establishing a direct link between potential of mean force and current rectification rate, we demonstrate that rectification caused by energy barrier asymmetry depends on the nature of the permeating ion, can be tuned by pore polarity, does not require ion binding sites, conformational flexibility, or specific pore geometry, and, as such, may be widespread among ion channels.

One-Step Digital Light Processing 3D Printing of Robust, Conductive, Shape-Memory Hydrogel for Customizing High-Performance Soft Devices.

Mechanically robust and electrically conductive hydrogels hold significant promise for flexible device applications. However, conventional fabrication methods such as casting or injection molding meet challenges in delivering hydrogel objects with complex geometric structures and multicustomized functionalities. Herein, a 3D printable hydrogel with excellent mechanical properties and electrical conductivity is implemented via a facile one-step preparation strategy. With vat polymerization 3D printing technology, the hydrogel can be solidified based on a hybrid double-network mechanism involving in situ chemical and physical dual cross-linking. The hydrogel consists of two chemical networks including covalently cross-linked poly(acrylamide-co-acrylic acid) and chitosan, and zirconium ions are induced to form physically cross-linked metal-coordination bonds across both chemical networks. The 3D-printed hydrogel exhibits multiple excellent functionalities including enhanced mechanical properties (680% stretchability, 15.1 MJ/m3 toughness, and 7.30 MPa tensile strength), rapid printing speed (0.7-3 s/100 μm), high transparency (91%), favorable ionic conductivity (0.75 S/m), large strain gauge factor (≥7), and fast solvent transfer induced phase separation (in ∼3 s), which enable the development of high-performance flexible wearable sensors, shape memory actuators, and soft pneumatic robotics. The 3D printable multifunctional hydrogel provides a novel path for customizing next-generation intelligent soft devices.

A PVDF-HFP/YSZ nanofiber composite solid-state electrolyte by in-situ polymerization of 1,3-dioxolane for 4.5 V high-voltage NCM811 battery

Solid lithium metal batteries with solid polymer electrolytes have advantages in terms of high energy density and safety. However, their application is still hindered by unstable solid electrolyte interfaces (SEI and CEI) and uncontrolled dendrite growth. Here, a composite skeleton loaded with dielectric filler yttrium stabilized zirconia nanoparticles (YSZ) on the surface of PVDF-HFP nanofiber filaments is designed, and a novel composite solid electrolyte (CSE) is prepared by in-situ polymerization of DOL (1,3-dioxolane) on this framework to achieve safe and stable high-voltage lithium metal battery (LMB). The dual stable electrode interfaces (CEI and SEI) constructed by in-situ can effectively suppress the generation of lithium dendrites and suppress the degradation of the high-voltage NCM811 positive electrode structure and the generation of cracks in NCM811 particles, endowing the battery with extraordinary performance. The as-obtained CSE exhibits high ionic conductivity of 1.01 × 10−3 S cm−1 at 30 °C, the enlarged electrochemical window of 6.0 V, and the Li+ transference number is 0.72. The assembled Li|NCM811 battery is capable of stable cycling for 400 cycles at a cut-off voltage of 4.5 V and current density of 1C, with a capacity decay of only 0.074 % per cycle. .

Unveiling exceptional conduction mechanism and high proton conductivity in amorphous electrolyte for advanced ceramic fuel cells

The requirement of high ion conductive material working at low temperatures is highly demanding in fuel cells. This study explains a groundbreaking advancement in ceramic fuel cells by exploring the potential of amorphous Sm0.3Al0.7-oxide and the proton conduction mechanism of amorphous oxides. Opposite to conventional crystalline electrolytes, amorphous electrolytes showed superior ion conduction. To study the detailed mechanism of ion conduction, amorphous Sm0.3Al0.7-oxide was selected which exhibited an exceptional proton conductivity of 0.17 S/cm and a power density of 1100 mW/cm2 at 550 °C, significantly surpassing traditional electrolyte materials. Using advance characterization techniques, a new approach has been proposed to provide the reasons for the high conductivity of amorphous materials, which entails a complete mechanism that describes how disordered structure and disoriented grain boundaries facilitate efficient proton conduction by reducing energy barriers and enhancing ionic mobility. Also, it has been described how the high enthalpy and the high energy state of amorphous materials are suitable for enhancing proton conduction. This study aims to clarify why amorphous materials are promising candidates for future fuel cell applications, facilitating significant advancements in SOFC and PCFC technologies and paving the way for more efficient and sustainable energy solutions.

Fluorine-doped carbon coating of LiFe0.5Mn0.5PO4 enabling high-rate and long-lifespan cathode for lithium-ion batteries

The limited electron and ionic conductivity, along with the sluggish kinetics caused by the Jahn-Teller effect of Mn3+, impose constraints on the electrochemical performance of LiFexMn1-xPO4. Herein, the surface of LiFe0.5Mn0.5PO4 (LFMP) is modified with a F-doped carbon using the solvothermal and calcination methods. The incorporation of F-doped carbon coating, along with the formation of interfacial F-Li, F-Fe and F-Mn bonds between the carbon layer and LFMP nanoparticles, significantly mitigates charge transfer resistance, facilitates rapid electron transfer, as well as enhances Li+ diffusion kinetics. The LFMP@C-F2 cathode prepared in this study exhibits an unexceptionable capacity retention of 90.5 % after 300 cycles at a low rate of 0.2C and a capacity retention of 78.8 % over 1000 cycles at a high rate of 1C. When incorporated into the solid battery configuration (Li/PEO-LATP CSE/LFMP@C-F2), it exhibits an initial discharge specific capacity of 148 mAh g−1 and maintains a capacity retention of 85.8 % after 60 cycles at 0.1C, thereby offering an innovative approach to enhance the performance of LFMP in terms of cycling stability and rate capacity in lithium-ion batteries, as well as to apply LFMP into solid-state lithium batteries.

Discovering Multi-Compositional Li-Argyrodite Solid-State Electrolytes via Experimental Active Learning.

Significant research has focused on doping third-party elements into representative Li-Argyrodites, which typically consist of a metal cation, a sulfide anion, and a halide. These efforts have generally been limited to doping or substituting a single element at each atomic site in the Argyrodite structure, resulting in, at most, binary combinations at each site. Multi-elemental doping or substitution poses a challenge due to the so-called combinatorial explosion issue. Here, the study reports quaternary and ternary combinations at either the cation or anion sites, optimizing the composition for ambient-temperature ionic conductivity. Managing such a complex multi-compositional system requires artificial intelligence that surpasses human intuition. A particle swarm optimization (PSO) algorithm is employed within an active learning framework to tackle this multi-dimensional optimization problem. Unlike typical active learning approaches that rely on theoretical computational data, the process is driven by experimental data from the synthesis and characterization of a few hundred multi-compositional Argyrodite samples This experimental active learning approach ultimately enables identifying a novel multi-compositional Li-Argyrodite, exhibiting ambient-temperature ionic conductivity of 13.02 mS cm⁻¹ and enhanced cell performance, with the composition Li6.425Ge0.25Si0.375Sb0.375S4.8I1.2.

Evaluation of the electrical behavior of tungsten trioxide and cobalt oxide nanoparticles filled poly (ɛ-caprolactone) composite for optoelectronic devices

This study obtains the electrical characterization of nanocomposites comprising Poly(ɛ-caprolactone) (PCL), tungsten trioxide (WO3), and cobalt oxide (Co3O4) nanoparticles. The fabrication of these nanocomposites through a casting method aimed to enhance their electrical conductivity and dielectric properties. The AC conductivity (σac) was analyzed across varying frequencies, revealing a notable increase with the addition of Co3O4 nanoparticles, particularly up to the high content of Co3O4 nanoparticles. This enhancement is attributed to the formation of ion transport pathways and the increased amorphous regions within the PCL matrix. Dielectric properties were assessed through ε′ and ε'') measurements, which exhibited a decrease with increasing frequency, indicating the dielectric relaxation processes of the composite. The complex electric modulus analysis demonstrated a significant relationship between the real and imaginary components, suggesting potential ionic conductivity in the nanocomposites. Additionally, the Argand plot revealed a depressed semicircle, indicating a distribution of relaxation times, which further confirmed the enhancement of conductivity with raising laser ablation time. Overall, the results indicate that the addition of WO3 and Co3O4 nanoparticles significantly improves the electrical properties of PCL, making these nanocomposites suitable for various electrical applications.

Strengthened High-Concentration Quasi-Solid Electrolytes for Lithium Metal with Ultralong Stable Cyclability.

The lithium metal batteries coupled with nickel-rich LiNixCoyMn1-x-yO2 (x > 0.7) cathodes hold promise for surpassing the current energy density limit of lithium-ion batteries. However, conventional electrolytes containing free active solvents are highly susceptible to decomposition, particularly at the interfaces of lithium anode and high-voltage cathode. Herein, we have developed a composite quasi-solid electrolyte (CQSE) utilizing sulfated Al2O3 (S-Al2O3)-bridged cellulose triacetate (CTA) to stabilize the interfaces between the electrolyte and electrodes. S-Al2O3 competitively dissociates Li+ through coordination interactions with anions, facilitating the formation of a distinctive solvation structure characterized by prevalent ion pairs and aggregates. In addition, coordination of S-Al2O3 with CTA forms S-Al2O3-bridged CTA molecular chain networks, enhancing the mechanical strength of the CQSE and immobilizing free liquid molecules. Consequently, the CQSE demonstrates an enhanced tensile strength of up to 7.4 MPa and a high ionic conductivity of 1.8 × 10-3 S cm-1 at room temperature. Furthermore, the CQSE not only suppresses electrode-electrolyte side reactions but also enables the formation of an inorganic-rich solid/cathode electrolyte interphase. As a result, the Li|CQSE|LiNi0.83Co0.11Mn0.06O2 (NCM83) batteries retain 84% capacity after 1000 cycles at 1 C, with the pouch cells demonstrating 80% capacity retention after 250 cycles at 0.5 C.

Phase Transitions in a Vanthoffite-Type Compound, Na6Zn(SO4)4: Insights from In Situ PXRD and Raman Spectroscopy.

The study of phase transitions in minerals or synthetic compounds analogous to mineral structures is of fundamental interest in different scientific disciplines, with applications ranging from understanding the Earth's geological history to advancing materials science and technology. They provide valuable data and insight into developing new functional materials with desired properties. In this context, we have investigated the structural phase transitions of Na6Zn(SO4)4, a synthetic compound analogous to the Vanthoffite mineral Na6Mg(SO4)4, which occurs abundantly in nature as oceanic salt deposits. The room temperature crystal structure is refined from powder X-ray diffraction (PXRD) data, and it belongs to a monoclinic system, space group P21/c, with Z = 2. Differential scanning calorimetry analysis suggests the possibility of multiple structural phase transitions between 338 and 400 °C. These phase transitions are substantiated by in situ powder X-ray diffraction and Raman spectroscopy. PXRD data with temperature reveal structural phase transitions with a change in crystal symmetry accompanied by the appearance/disappearance of diffraction peaks. Further, the dynamics of the SO4 tetrahedra units are probed using variable temperature Raman spectroscopy to understand the mechanism of structural phase transitions. These phase transitions are driven by the anomalies of the molecular vibration of sulfate tetrahedra at higher temperatures as revealed from Raman data. Additionally, ionic conductivity measurements also depict these structural phase transitions with a change in slope with an increase in temperature.

Molecular structures of residual solvent in polyacrylonitrile based electrolytes: Implications for conductivity and stability.

Lithium-ion batteries increasingly play significant roles in modern technologies; however, increased energy density also raises concerns about electrolyte safety. Traditional electrolytes that use volatile organic solvents face risks of thermal runaways and fires from electrode shorting. In response, polymer-based solid electrolytes have been developed for replacement. Polyacrylonitrile (PAN) is a promising fire-resistant component for electrolyte fabrication, but its limited solubility necessitates using low-volatility solvents, which are notoriously difficult to remove in subsequent drying processes. Here, we use femtosecond two-dimensional infrared spectroscopy to provide an in-depth understanding of how residual solvent from processing affects the molecular structures and dynamics within a polymer electrolyte. To this end, linear and nonlinear infrared spectroscopies are employed to interrogate the molecular interactions in PAN-based electrolytes containing various contents of N,N-dimethylformamide (DMF). We show that the amount of DMF within the PAN electrolyte affects the Li+ structure. The coordination can proceed through the carbonyl group and/or the amide nitrogen to form antiparallel structures with the nitrile groups of PAN through dipole-dipole interactions. The free motion of DMF is drastically inhibited upon interaction with Li+ and PAN, which decreases the ionic conductivity and potentially affects the stability (resistance toward removal and chemical decomposition). These findings have implications for the design and processing of solid polymer electrolytes.

In-situ analysis of water transport properties through a reinforced composite membrane in polymer electrolyte membrane fuel cells

This study presents a comprehensive in-situ analysis of water transport properties through an expanded polytetrafluoroethylene (ePTFE)-reinforced composite membrane, representing a notable advancement over previous studies that primarily focused on Nafion membranes. The membrane water content was measured using dynamic vapor sorption (DVS) isotherms, and the temperature dependence of sorption was investigated using a new dual-mode sorption (NDMS) model, which showed an excellent fit with an adjusted coefficient of determination (Radj2) greater than 0.96. By employing the hydrogen pumping mode and polymer electrolyte membrane fuel cells (PEMFC) mode, we established empirical correlations for the coefficients of water diffusion, electro-osmotic drag (EOD), and ionic conductivity as functions of water content and cell temperature. The correlation results exhibited a maximum relative error of less than 3.14 %. In addition, we isolated the water diffusion coefficients of the gas diffusion layer (GDL) and catalyst layer (CL) from the membrane to refine our analysis. This study enhances the understanding of water management in PEMFCs by establishing correlations for water diffusion, EOD coefficient, and ionic conductivity. These findings underscore the potential of reinforced composite membranes in advancing fuel cell technology by optimizing water transport, which is crucial for improving fuel cell performance and enabling more precise PEMFC modeling.

Self-Assembled Monolayer in Hybrid Quasi-Solid Electrolyte Enables Boosted Interface Stability and Ion Conduction.

Complex interactions between the inorganic solid electrolyte (ISE) and the liquid electrolyte (LE) give rise to challenges of achieving durable interface stability in hybrid quasi-solid electrolytes (HQSE), and the influence on the involved ISE surface ionic conductivity also needs to be investigated. Here, 4-chlorobenzenesulfonic acid (CBSA) is utilized to establish a self-assembled monolayer (SAM) on the surface of Li6.4La3Zr1.4Ta0.6O12 (LLZTO), which is then incorporated into PEGDA-based in situ polymerized HQSE. The results show that the introduction of CBSA significantly improves the LLZTO/LE interface stability with the optimized solvation structure, resulting in a favorable ionic conductivity (1.19 mS⋅cm-1) and an increasing Li+ transference number (0.647). Mechanisms for the promotion of ionic conduction and interfacial stability of SAM-HQSE are unveiled through the density functional theory (DFT) combined with Raman spectra and 7Li solid-state nuclear-magnetic-resonance. There are no short-circuits in the Li|SAM-HQSE|Li cells after 1000 h. The LFP|SAM-HQSE|Li cells or LFP|SAM-HQSE|Graphite pouch cells respectively achieve the capacity retention of 91.2 % and 87.0 % with the 0.5.C-rate for 500 and 300 cycles. This facile and effective strategy proposed in this work make it accessible for constructing the stable surface micro-environments of LLZTO where boost and homogenize the Li+ conduction in a hybrid quasi-solid electrolyte system.