Proton Conductivity Research Articles

Effective Proton Conduction in Quasi‐Solid Zinc‐Manganese Batteries via Constructing Highly Connected Transfer Pathways

Elusive ion behaviors in aqueous electrolyte remain a challenge to break through the practicality of aqueous zinc‐manganese batteries (AZMBs), a promising candidate for safe grid‐scale energy storage systems. The proposed electrolyte strategies for this issue most ignore the prominent role of proton conduction, which greatly affects the operation stability of AZMBs. Here we report a water‐poor quasi‐solid electrolyte with efficient proton transfer pathways based on the large‐space interlayer of montmorillonite and strong‐hydration Pr3+ additive in AZMBs. Proton conduction is deeply understood in this quasi‐solid electrolyte. Pr3+ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α‐MnO2 cell could achieve a high specific capacity of 433 mAh g–1 at 0.4 mA cm–2 and an excellent stability up to 800 cycles with a capacity retention of 92.2% at 0.8 mA cm–2 in such water‐poor quasi‐solid electrolyte for the first time. Ah‐scale pouch cell with mass loading of 15.19 mg cm–2 sustains 100 cycles after initial activation, which is much better than its counterparts. Our work provides a new path for the development of zinc metal batteries with good sustainability and practicality.

Effective Proton Conduction in Quasi‐Solid Zinc‐Manganese Batteries via Constructing Highly Connected Transfer Pathways

Elusive ion behaviors in aqueous electrolyte remain a challenge to break through the practicality of aqueous zinc‐manganese batteries (AZMBs), a promising candidate for safe grid‐scale energy storage systems. The proposed electrolyte strategies for this issue most ignore the prominent role of proton conduction, which greatly affects the operation stability of AZMBs. Here we report a water‐poor quasi‐solid electrolyte with efficient proton transfer pathways based on the large‐space interlayer of montmorillonite and strong‐hydration Pr3+ additive in AZMBs. Proton conduction is deeply understood in this quasi‐solid electrolyte. Pr3+ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α‐MnO2 cell could achieve a high specific capacity of 433 mAh g–1 at 0.4 mA cm–2 and an excellent stability up to 800 cycles with a capacity retention of 92.2% at 0.8 mA cm–2 in such water‐poor quasi‐solid electrolyte for the first time. Ah‐scale pouch cell with mass loading of 15.19 mg cm–2 sustains 100 cycles after initial activation, which is much better than its counterparts. Our work provides a new path for the development of zinc metal batteries with good sustainability and practicality.

A {Ru(C6H6)}-Containing Isopolymolybdate with Good Photocatalytic Activity for Oxidative Coupling of Amines, and Proton Conduction Properties

A {Ru(C₆H₆)}-Containing Isopolymolybdate with Good Photocatalytic Activity for Oxidative Coupling of Amines, and Proton Conduction Properties

A High‐capacity Benzoquinone Derivative Anode for All‐organic Long‐cycle Aqueous Proton Batteries

AbstractQuinone compounds, with the ability to uptake protons, are promising electrodes for aqueous batteries. However, their applications are limited by the mediocre working potential range and inferior rate performance. Herein, we examined quinones bearing different substituents, and for the first time introduce tetraamino‐1,4‐benzoquinone (TABQ) as anode material for proton batteries. The strong electron‐donating amino groups can effectively narrow the band gap and lower the redox potentials of quinone materials. The protonation of amino groups and the amorphization of structure result in the formation of an intermolecular hydrogen‐bond network, supporting Grotthuss‐type proton conduction in the electrode with a low activation energy of 192.7 meV. The energy storage mechanism revealed by operando FT‐IR and ex situ XPS features a reversible quinone‐hydroquinone conversion during cycling. TABQ demonstrates a remarkable specific capacity of 307 mAh g−1 at 1 A g−1, which is one of the highest among organic proton electrodes. An all‐organic proton battery of TABQ//TCBQ has also been developed, achieving exceptional stability of 3500 cycles at room temperature and excellent performance at sub‐zero temperature.

A High-Performance Polyimide Composite Membrane with Flexible Polyphosphazene Derivatives for Vanadium Redox Flow Battery.

A sulfonated polyimide, S-F-abSPI, with alkyl sulfonic acid side chains, and a polyphosphonitrile derivative, poly[4-methoxyphenoxy (4-fluorophenoxy) phosphazene] (PFMPP), were designed and synthesized. Composite modification of the S-F-abSPI membrane was carried out using PFMPP, resulting in the preparation of composite membranes with different composite ratios, which were then subjected to performance testing and characterization. Experimental results revealed a significant enhancement in the proton conductivity of the S-F-abSPI membrane, reaching 0.116 S cm-1, slightly higher than that of the N212 membrane. The S-F-abSPI/1% PFMPP composite membrane exhibited the optimal comprehensive performance, with a surface resistance as low as 0.54 Ω cm2, comparable to that of the N212 membrane. At a high current density of 200 mA cm-2 during charge-discharge, the composite membrane achieved a voltage efficiency (VE) of 83.12% and an energy efficiency (EE) of 81.95%. Cycling tests over 200 cycles demonstrated the composite membrane's excellent long-term cycling stability. The alkyl sulfonic acid side chains enhanced the proton conductivity of the membrane, while electrostatic potential distribution calculations indicated strong interactions between PFMPP and the base membrane, enhancing the membrane's mechanical strength, reducing vanadium ion permeability, and improving chemical stability and vanadium ion selectivity. This composite membrane holds promise for high-performance VRFB applications.

High Proton Conductivity of Sulfonate-amine Ionic HOFs and Enhancement of SPEEK Composite Membranes.

Hydrogen-bonded organic frameworks (HOFs) are crystalline materials assembled by intermolecular hydrogen-bonding interactions, and their hydrogen-bonding structures are effective pathways for proton transport. Herein, we synthesize iHOF-45 using 4,4'-diaminodiphenylmethane and 1,3,6,8-pyrenetetrasulfonicacid sodium salt with 2D hydrogen-bonding networks. The stability of ionic HOFs (iHOFs) can be enhanced by introducing ionic bonds in addition to hydrogen-bonding forces. Thermal analyses demonstrated that iHOF-45 exhibited excellent thermal stability up to 332 °C. The proton conductivity of iHOF-45 was evaluated, demonstrating a notable increase with rising temperature and RH. At 100 °C and 98 % RH, the conductivity reached 5.25×10-3 S cm-1. The activation energy (Ea) of iHOF-45 was calculated to be 0.281 eV for 98 % RH, and the proton conduction was attributed to the Grotthuss mechanism, whereby the protons were transported in 2D hydrogen-bonding networks. Moreover, iHOF-45 was doped into SPEEK to prepare composite membranes, the proton conductivity of the 15 % iHOF-45/SPEEK membrane reached 9.52×10-2 S cm-1 at 80 °C and 98 % RH, representing a 45.1 % increase over that of the SPEEK. This suggests that doping enhances the proton conductivity of SPEEK and providing a reference for the development of high proton conductivity materials.

Enhancing SO2 Sensing Performance of a Fuel Cell-Type Sensor with N-Doped Cu/CNT Aerogel Electrode and COF/Nafion Electrolyte.

Sulfur dioxide (SO2) is a common environmental pollutant with significant hazards. However, sensors for SO2 real-time monitoring at room temperature often face problems such as a poor response and sluggish recovery. In this work, a fuel cell-type gas sensor based on nitrogen-doped carbon nanotube (CNT) aerogels loaded with Cu particle electrode material and COF/Nafion composite electrolyte was developed, which exhibited excellent SO2 sensitivity and fast response/recovery. The aerogel scaffold provided a high specific surface area and high electrical conductivity, and Cu particles provided good catalytic activity to SO2. In addition, N doping further enhanced the SO2 capture capability and conductivity of the electrode material. For electrolyte construction, covalent organic framework (COF) nanosheets were synthesized by a bottom-up approach and blended with Nafion to prepare the COF/Nafion membrane; the composite membrane showed higher proton conductivity. Owing to these advantages, the fuel cell-type sensor exhibited an outstanding response of -3008.5 nA to 50 ppm of SO2 with a rapid response time (35 s) and recovery time (77 s). Moreover, the rigid nanochannels of COF nanosheets improved the water retention properties of the electrolyte; this will help to simplify the structure of fuel cell-type sensors and provide a significant stimulus for their miniaturization. Based on the great sensing performance, a fuel cell-type SO2 sensor is integrated into a portable detector and evaluated in the context of dynamic environmental monitoring. The results show that the fuel cell-type sensor with the carefully designed electrode and electrolyte will have great potential in environmental monitoring and safety assurance.

Construction and Comparative Research of Two MOFs Proton Conducting Materials Containing Nitro Groups.

In field of electrochemistry, there has been a growing interest in the potential applications of proton-conducting metal-organic frameworks (MOFs). Therefore, how to design and synthesize MOFs with high proton conductivity is considered crucial. In this study, two examples of nitro-containing Cd-based MOFs, MOF-1 {[Cd3(TIPE)1.5(NO3)5Cl(H2O)2]·17H2O}n and MOF-2 {[Cd(TIPE)0.5(nip)]·10H2O}n (TIPE=1,1,2,2-tetrakis(4-(1H-imidazole-1-yl)phenyl)ethene, H2nip=5-Nitroisophthalic Acid), had been successfully designed and synthesized, and their proton-conducting properties were thoroughly investigated. Notably, both materials displayed peak proton conductivity at 98% RH and 90 °C, exhibiting values of 9.13 × 10-3 and 3.00 × 10-3 S∙cm-1 for MOF-1 and MOF-2, respectively. The plausible proton conduction pathways and mechanisms were elucidated through structural analyses, water vapor adsorption studies, and the determination of activation energy (Ea) values. It was found that the difference in proton conductivity between MOF-1 and MOF-2 was mainly associated with the different water absorption rates of the samples. The uniqueness of this study was that for the first time conducted an in-depth study of the role of nitrate in proton conduction, providing new ideas for designing materials with excellent proton conductivity.

Experimental and Theoretical Investigation of Anisotropic Proton Conduction in Two-Dimensional Metal-Organic Frameworks.

Two-dimensional (2D) materials are known for their potential to exhibit anisotropic transport properties due to their layered structures. However, the anisotropic ion conduction of 2D metal-organic frameworks (MOFs) has been rarely explored. In this study, we investigated the anisotropic proton conduction along the in-plane and stacking directions of two analogs of undulating 2D MOFs: [Mn(salen)]2[Pt(CN)4]·H2O (MnPt) and [Mn(salen)]2[PtI2(CN)4]·H2O (MnPtI). This investigation was conducted using both experimental methods, involving single crystals, and theoretical calculations. Compared to the relatively isotropic proton conduction of MnPt at 85 °C and 95% relative humidity (RH), with a stacking direction conductivity (σstacking) of 1.8 × 10-5 S/cm, which is approximately 2.9 times the in-plane conductivity (σin-plane), MnPtI exhibited highly anisotropic proton conduction. The σstacking of MnPtI under the same conditions (85 °C, 95% RH) was 1.5 × 10-4 S/cm, which is 83 times higher than its σin-plane. Additionally, the activation energy for proton conduction in MnPtI ranged from 0.65 to 0.73 eV, which is higher than the 0.48 eV observed for MnPt. Theoretical calculations confirmed that slight differences in local structures, including node distortions between MnPt and MnPtI, significantly influenced the activation energies for water migration. This was attributed to the formation of hydrogen bonds between layers and water molecules.

Engineering π‐Electron Bridge Enables Low‐Potential 2D Redox Polymer Anodes for High‐Voltage Aqueous All‐Organic Batteries

AbstractAqueous all‐organic batteries (AAOBs) have emerged as a hot topic but their development was plagued by limited choices of anode materials, generally facing an intractable trade‐off between low potential and high stability. Here, we propose a novel π‐electron bridge engineering strategy to explore a class of 2D dioxin‐bridged redox covalent organic polymer (RCOP) as trade‐off‐breaking anodes for high‐voltage AAOBs. By establishing a tunable RCOP platform, we perform theoretical study to scrutinize how bridge units between active sites affect the electrode potential and redox activity for the first time. We discover that compared to common pyrazine bridge, the weakened conjugation and strong electron donor character of the proposed dioxin bridge can induce elevated LUMO level and enriched π‐electron populations in active sites, heralding a low electrode potential and enhanced redox activity. Besides, the nonaromaticity‐induced molecular flexibility of dioxin bridge mitigates intermolecular stacking for sufficient active sites exposure. To experimentally corroborate this, a new dioxin‐bridged 2D RCOP (D‐HATN) and its pyrazine‐bridged analogue (P‐HATN) are synthesized for proof‐of‐concept demonstration. D‐HATN displays excellent compatibility with Na+/Zn2+/NH4+/H3O+ and obviously lower redox potentials in various dilute electrolytes compared to P‐HATN and most reported organic anodes, while featuring rapid Grotthuss‐type proton conduction and unprecedented durability in acid – 91.8 % capacity retention after 20000 cycles. Thus, the D‐HATN‐involved all‐organic proton battery delivers an average output voltage of 0.75 V, which can be further elevated to 1.63 V with alkaline‐acidic hybrid electrolyte design, affording markedly‐increased specific energy.

Research Progress in Enhancing Proton Conductivity of Sulfonated Aromatic Polymers with ZIFs for Fuel Cell Applications

The escalating global temperatures and their adverse effects underscore the growing imperative for the widespread adoption of clean fuels, notably hydrogen. Proton Exchange Membrane Fuel Cells (PEMFC) emerge as a pivotal green energy technology, facilitating electricity and water generation. The optimization of PEMFC efficiency hinges on the judicious selection and fabrication of polymer membranes. Within innovative materials, Zeolitic Imidazolate Frameworks (ZIFs) represent a novel subclass within the expansive family of Metal-Organic Frameworks (MOFs). ZIFs exhibit promising potential in PEMFCs, owing to their distinctive properties such as a substantial contact surface, inherent porosity, and a sizable pore volume. This comprehensive review delves into composite membranes featuring ZIFs, shedding light on their chemical and thermal attributes. Additionally, the exploration extends to elucidating the diverse applications of ZIF compounds, accompanied by an in-depth discussion of selected chemical and thermal properties inherent to ZIF compounds. Incorporating ZIFs into various polymers yielded intriguing outcomes, demonstrating a notable enhancement in proton conductivity. The compilation of this review aims to provide researchers with foundational insights into the realm of ZIFs, serving as a valuable resource for future investigations and advancements in the field.

Ba3Ti0.4W1.6O8.6: An Oxygen- and B-Site-Deficient 9R Hexagonal Perovskite Exhibiting Triple Conduction.

The hexagonal perovskite derivatives Ba3M'M″O8.5 featuring a hybrid structure composed of 9R hexagonal perovskite and palmierite structure motifs exhibit significant oxide ionic conductivity due to the highly disordered oxide-ion and M-cation sublattices. Herein, we report the structure and electrical properties of the perovskite Ba3Ti0.4W1.6O8.6. Three-dimensional (3D) electron diffraction (ED), neutron powder diffraction (NPD), and neutron pair distribution functions (nPDF) revealed a 9R hexagonal perovskite structure for Ba3Ti0.4W1.6O8.6 with fully occupied central M2 sites, partially occupied outer M1 sites, and oxygen-deficient cubic c-BaO2.6 sublayers. These cation and oxygen arrangements differ significantly from those in Ba3M'M″O8.5 and enable Ba3Ti0.4W1.6O8.6 to capture atmospheric water and O2, resulting in triple conduction (oxide ion, proton, and hole) under wet air conditions. Proton and oxide ion conductions predominate at temperatures <400 and >650 °C in wet Ar and dry air, respectively. Bond-valence site energy calculations, together with structure analysis, deciphered that the two-dimensional oxide-ion diffusion pathways along the c-BaO2.6 layers are disrupted by the M1 vacancies, thereby resulting in relatively low oxide ionic conductivity. Our findings open up a new strategy of utilizing the cation's propensity of coordination geometry to design new oxygen- and B-site-deficient perovskites and thus achieve desired conductivity.

Modulation of the Chirality and Dynamics of Self-Assembled Nanocellulose-Chiral C-Dot Film for Chiral Sensing Applications.

The detection and sensing of chirality using chiral biomaterials are growing areas of research in advanced bioelectronics. As a result, chiral-controlled biomaterials are crucial for advancing current technologies in chiral sensing applications within biosystems. A chiral carbon dot (C-dot) modulated self-assembled emissive cellulose nanocrystal (CNC) film is developed where the chirality of the CNC film can be tempered between left-handed and right-handed chirality after being doped with chiral L/D-C-dots in CNCs (C-dot-CNC film), transferring the chirality from C-dots to CNCs. The interaction between C-dots, CNCs, and carrier dynamics is investigated using a variety of steady-state and time-resolved PL spectroscopy techniques. The chiral C-dot enhanced the protonic conductivity across the CNC via the formation of hydrogen bonds with its surface functional groups and water molecules. Further, the chiral CNC-C-dots photoelectrodes demonstrate an excellent ability to distinguish between left-handed and right-handed small molecules. These findings on the underlying mechanism of spin selectivity between chiral CNC-C-dot and chiral ligand hold promise for the development of efficient chiral-sensing electronic devices.

Design of Functional Gyroid Minimal Surfaces Transporting Proton Based Solely on Surface Hopping Conduction Mechanism.

Surface proton hopping conduction (SPHC) mechanisms is an important proton conduction mechanism in conventional polymer electrolytes, along with the Grotthuss and vehicle mechanisms. Due to the small diffusion coefficient of protons in the SPHC mechanism, few studies have focused on the SPHC mechanism. Recently, it has been found that a dense alignment of SO3 - groups significantly lowers the activation energy in the SPHC mechanism, enabling fast proton conduction. In this study, a series of polymerizable amphiphilic-zwitterions is prepared, forming bicontinuous cubic liquid-crystalline assemblies with gyroid symmetry in the presence of suitable amounts of bis(trifluoromethanesulfonyl) imide (HTf2N) and water. In situ polymerization of these compounds yields gyroid-nanostructured polymer films, as confirmed by synchrotron small-angle X-ray scattering experiments. The high proton conductivity of the films on the order of 10-2 S cm-1 at 40 °C and relative humidity of 90% is based solely on the SPHC mechanism.

Activation of the Influenza B M2 Proton Channel (BM2).

Influenza B viruses have cocirculated during most seasonal flu epidemics and can cause significant human morbidity and mortality due to their rapid mutation, emerging drug resistance, and severe impact on vulnerable populations. The influenza B M2 proton channel (BM2) plays an essential role in viral replication, but the mechanisms behind its symmetric proton conductance and the involvement of a second histidine (His27) cluster remain unclear. Here we performed membrane-enabled continuous constant-pH molecular dynamics simulations on wildtype BM2 and a key H27A mutant channel to explore its pH-dependent conformational switch. Simulations captured the activation as the first histidine (His19) protonates and revealed the transition at lower pH values compared to AM2 is a result of electrostatic repulsions between His19 and preprotonated His27. Crucially, we provided an atomic-level understanding of the symmetric proton conduction by identifying preactivating channel hydration in the C-terminal portion. This research advances our understanding of the function of BM2 function and lays the groundwork for further chemically reactive modeling of the explicit proton transport process as well as possible antiflu drug design efforts.

Y, Yb, and Gd tri-doping on B-site of Ba(Zr, Ce)O3-δ with improved proton conduction performance

Perovskite-type proton conducting electrolytes are garnering significant attention due to its key role in protonic ceramic electrochemical cells (PCEC) and its application in hydrogen sensors (HS) used for metal melt measurements. Developing high proton conduction perovskite materials with good chemical stability is always a worldwide research focus. In this paper, Y, Yb and Gd triple-doping on B-site of BaCeO3-BaZrO3 solid solution were carried out to investigate the effect of gadolinium doping on the performance of protonic conducting electrolytes. BaZr0.1Ce0.7(Y0.5Yb0.5)0.2-xGdxO3-δ (x = 0, 0.1, 0.15 and 0.2), which were also referred as BZCYYbGdx (x = 0, 10, 15 and 20), were synthesized by solid-state reaction at 1600 °C for 10 h. It is found that BZCYYbGd15 has the highest proton conductivity and proton transfer number among the four prepared materials. The proton mobility of BZCYYbGd15 is 4.06 × 10−6 cm2/(Vꞏs) at 800 °C, which increases with an increased temperature. Its proton transfer number is higher than 0.9 at 500 °C under the atmosphere of PH2O = 0.018 atm. A moderate doping of gadolinium increases the temperature threshold for proton conduction. Proton, oxygen vacancy, electron hole and total conductivity activation energies of BZCYYbGd15 under the wet atmosphere are found to be 0.74, 1.58, 1.41 and 0.92 eV, respectively. Furthermore, the chemical stability of pellets is improved after gadolinium doping. This study provides a reference value for future research on high proton conduction electrolytes.

Preparation of high temperature proton exchange membrane through covalent organic framework doped polyvinylidene fluoride nanofibers

Covalent organic framework (COF) exhibits the great potential to promote proton conduction under low relative humidity for proton exchange membranes (PEMs). In this research, quick and stable proton conduction has been achieved since the prepared COF and polyvinylidene fluoride (PVDF) nanofibers are believed to constitute successive proton conduction channels. The PVDF-COF nanofibers membrane is prepared through the in-situ growth of COF along PVDF nanofibers. The fine compatibility can drive the stable combination of COF with the PVDF nanofibers in PVDF-COF nanofibers. Most importantly, the fibrous PVDF nanofibers accelerate proton conduction through confining the proton conduction pathways. Additionally, ionic liquids of 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-butyl-3-methylimidazole hexafluorophosphate (BmimPF6) as proton conduction carriers have been introduced to accelerate proton conduction in the prepared PVDF-COF/BmimCl/PA and PVDF-COF/BmimPF6/PA membranes. Phosphoric acid (PA) molecules are combined by COF and ionic liquid cations with the formation of intermolecular hydrogen bonds. As a result, the PVDF-COF/BmimPF6/PA membrane exhibits the proton conductivity of (1.81 ± 0.07) × 10−1 S/cm at 160 °C. The long-term proton conductivity stability is determined, deriving from the proton conductivities of 1.77×10−2 S/cm at 80 °C and 1.42×10−2 S/cm at 110 °C in the 400 h non-stop measurement. The single fuel cell equipped with the PVDF-COF/BmimPF6/PA membrane represents the open circuit voltage of 0.927 V and the peak power density of 178.8 mW/cm2 at 100 °C, 0.907 V and 326.5 mW/cm2 at 120 °C.

Electrospun Sulfonated Poly(ether ether ketone) and Chitosan/Poly(vinyl alcohol) Bifunctional Nanofibers to Accelerate Proton Conduction at Subzero Temperature.

Multilayered microstructures can accelerate the proton conduction process in proton exchange membranes (PEMs). Herein, we design and construct PEMs with microstructures based on bifunctional nanofibers and sulfonated poly(ether ether ketone) (SPEEK) nanofibers. Specifically, the bifunctional nanofibers composed of poly(vinyl alcohol) and chitosan are prepared and then combined with the electrospun SPEEK nanofibers. The stable microstructure is derived from the compatible interfacial property of nanofibers and the formed hydrogen bonds. The multilayered microstructure consisting of nanofibers accelerates the proton conduction even at subzero temperature because of regulating the proton conduction pathways. Specifically, the (SKNF/CPNF/SKNF)/PA membrane exhibits the proton conductivities of (0.951 ± 0.138) × 10-2 S/cm at -30 °C and (7.32 ± 0.37) × 10-2 S/cm at 160 °C. Additionally, the fine proton conductivity stability is demonstrated by the proton conductivity in the long-term test and the cooling/heating cycle test, such as 1.67 × 10-2 S/cm at -30 °C (after 1000 h), 4.52 × 10-2 S/cm at 30 °C (after 810 h), 1.12 × 10-2 S/cm at -30 °C, and 1.01 × 10-1 S/cm at 30 °C in the cooling/heating process (5 cycles). The single fuel cell possesses an open-circuit voltage of 0.886 V and a peak power density of 0.508 W/cm2 at 130 °C.

Polymeric ionic liquids and piperidinium synergistically improve proton conductivity and acid retention of polybenzimidazole-based proton exchange membranes

Amino-type polybenzimidazole is prepared, then ionic liquid with three nitrogen positive sites ([CTDTr]Br3) is polymerized into polymeric ionic liquids (PILs) by in-situ radical polymerization, and AmPBI-CTDTr-Px membranes were prepared by piperidinium (PPd) and [CTDTr]Br3 combination to cross-linked with AmPBI. Following treatment with KOH and phosphoric acid (PA), the ion pairs (N+ - H2PO4-) generated in the composite membrane system can enhance proton conductivity and facilitate proton transport. The AmPBI-CTDTr-Px membranes shown exceptional PA retention as a result of the alkaline properties of both [CTDTr]Br3 and PPd, which can engage in acid-base interactions with phosphoric acid. Specifically, the proton conductivity of AmPBI-CTDTr-P5 at 180 °C is 129.7 mS cm-1, which is 2.52 times that of pure membranes. Acid retention of AmPBI-CTDTr-P5 at 80 °C/40% RH and 160 °C are 64.4% and 84%.

Proton direct transport channels incorporated with protonated porphyrin hyper-crosslinked structures for high proton conductivity HT-PEMs

The trade-off between the mechanical properties and proton conductivity of phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes presents a significant challenge to their development and practical application as high-temperature proton exchange membranes (HT-PEMs). In this study, we prepared hyper-crosslinked poly[2,2′-(p-oxydiphenylene)-5,5′-benzimidazole] (OPBI) membranes with porphyrins (TBPP) containing a substantial amount of halogen. The combination of the protonation effect of porphyrin and the support of the hyper-crosslinked structure results in TBPP-OPBI crosslinked membranes exhibiting excellent mechanical strength and proton conductivity at high PA doping levels (ADLs). In particular, the TBPP-15-OPBI crosslinked membrane exhibits high proton conductivity of 244 mS cm−1 at 180 °C, which is 3.64 times greater than that observed in the OPBI membrane. The H2/air fuel cells based on the TBPP-15-OPBI crosslinked membranes exhibit a peak power density of 521.1 mW cm−2 at 160 °C without humidification and back pressure, as well as excellent durability (over 100 h). Thus, this work provides a straightforward and feasible structural design approach to comprehensively enhance the performance of PA-PBI proton exchange membranes.