Application of 2D nanomaterial MXene in anion exchange membranes for alkaline fuel cells: Improving ionic conductivity and power density

Two types of new 2D MXenes (LiF–Ti₃C₂T_x and NH₄HF₂–Ti₃C₂T_x) were prepared by selective etching of Ti₃AlC₂ with LiF/HCl and NH₄HF₂ aqueous solutions, respectively, and they were introduced as nanofillers into quaternized polysulfone/polyquaternium-10 (QPSU/PQ-10) anion exchange membranes (AEMs) with semi-interpenetrating polymer network, thereby preparing two types of MXene-doped QPSU/PQ-10 AEMs. The resulting MXene-doped QPSU/PQ-10 AEMs have obvious nanoscale microphase-separated morphologies, and their ionic conductivity and power density are significantly improved compared with the pristine QPSU/PQ-10 AEM. Among them, the ionic conductivity and power density of NH₄HF₂–Ti₃C₂T_x MXene-doped AEM can reach 88.76 mS/cm at 80 °C and 106.28 mW/cm² at 60 °C, respectively, which are 26.3% and 37.5% higher than those of the pristine QPSU/PQ-10 AEM. Additionally, the MXene-doped QPSU/PQ-10 AEMs with semi-interpenetrating network have moderate water uptake and swelling ratio, excellent thermal and mechanical properties, as well as good oxidation resistance and alkaline stability, which can meet the application requirements of AEMs for fuel cells, exhibiting their bright application prospects in fuel cells.     

Novel quaternized carbon dots modified polysulfone-based anion exchange membranes with improved performance

At present, low conductivity and poor chemical stability are still the biggest challenges in the research on anion exchange membranes (AEMs). Herein, novel nanocomposite AEMs were first constructed by introducing quaternized carbon dots (QCDs) into the imidized polysulfone matrix (Im-PSU). QCDs were synthesized by quaternization of CDs derived from citric acid and ethylenediamine. The physicochemical properties and electrochemical properties of the nanocomposite AEMs were significantly improved due to the introduction of QCDs. It was found that the QCDs can improve the ion transport channel of the nanocomposite AEMs. Compared with pure Im-PSU AEM, the OH⁻ conductivity and physicochemical properties of the nanocomposite membranes were enhanced, and the OH⁻ conductivity of ImPSU-1.0%-QCDs composite membrane can reach 109.3 mS cm⁻¹ at 80 °C, and 61.2% initial OH⁻ conductivity was maintained in 1.0 M NaOH solution for 500 h at 60 °C. Our research proves that the nanofiller with a small size can better improve the performance of composite AEMs, and provide an efficient strategy for future research work in the design and preparation of AEMs.     

A facile fabrication of functionalized rGO crosslinked chemically stable polysulfone-based anion exchange membranes with enhanced performance

Introducing more ionic conductive groups in polymer-based anion exchange membranes (AEMs) can improve the ion exchange capacity and further overcome the disadvantage of low ion conductivity for AEMs. However, the excessive swelling of AEMs caused by exorbitant IEC value may reduce the dimensional stability of membranes. So it is extremely important to modify the structures of AEMs. Herein, we proposed a facile strategy to construct reduced graphene oxide (rGO) stable crosslinked polysulfone-based AEMs with improved properties. rGO was non-covalently modified with pyrene-containing tertiary amine small molecule and polymer via π-π interactions. The as-prepared functionalized rGO (TrGO and PrGO) as both cross-linkers and fillers to fabricate quaternized polysulfone (QPSU)-based AEMs (CQPSU-X-TrGO and CQPSU-X-PrGO) for the first time. The cross-linked membranes can tighten the internal packing structure, and enhance the alkaline resistance, ion conductivity and oxidative stability of AEMs. Furthermore, the hydrophilicity and flexibility of the CQPSU-X-PrGO membranes were significantly improved as compared with that of CQPSU-X-TrGO membranes. PrGO-crosslinked membranes (CQPSU-2%-PrGO, σ_OH⁻ = 117.7 mS/cm) displayed higher ionic conductivities at 80 °C than TrGO-crosslinked membranes (CQPSU-1%-TrGO, σ_OH⁻ = 87.2 mS/cm). The remarkable nanophase separation can be observed in the CQPSU-X-PrGO membranes by TEM. This feasible strategy can be efficiently used to prepare new type of crosslinked organic-inorganic nanohybrid AEMs with excellent chemical stability and high ionic conductivity.     

Simultaneously enhanced hydroxide conductivity and mechanical properties of quaternized chitosan/functionalized carbon nanotubes composite anion exchange membranes

Low-cost biopolymer chitosan has received considerable attention in the field of anion exchange membranes (AEMs) because it can be easily quaternized and avoids the carcinogenic chloromethylation step. Simultaneously increasing the ionic conductivity and improving mechanical properties of quaternized chitosan (QCS) is key for its high-performance application. In this study, new composite AEMs consisting of QCS and functionalized carbon nanotubes (CNTs) were prepared. CNTs were coated with a thick silica layer onto which high-density quaternary ammonium groups were then grafted. The insulator silica coating effectively prohibits electron conduction among nanotubes and the grafted –NR₃⁺ provides new OH⁻ conductive sites. Incorporating 5 wt% functionalized CNTs into the matrix enhanced ionic conductivity to 42.7 mS cm⁻¹ (80 °C) which was approximately 2 times higher than that of pure QCS. The effective dispersion of CNTs and appropriate interfacial bonding between nanofiller and QCS improved the mechanical properties of AEMs, including both the strength and toughness of the composite membranes. An alkaline direct methanol fuel cell equipped with the composite membrane (5% functionalized CNTs loading) produced an maximum power density of 80.8 mW cm⁻² (60 °C), which was 57% higher than that of pure QCS (51.5 mW cm⁻²). This study broadens the application of natural polymers and provides a new way to design and fabricate composite AEMs with both improved mechanical properties and electrochemical performance.     

Novel quaternized polysulfone/ZrO2 composite membranes for solid alkaline fuel cell applications

A novel composite anion exchange membrane, zirconia incorporated quaternized polysulfone (designated as QPSU/ZrO₂), is prepared by solution casting method. The characteristic properties of the QPSU/ZrO₂ composite polymer membranes are investigated by thermogravimetric analysis, X-ray diffraction and electrochemical impedance spectroscopy. The morphology of the composite membrane is observed by SEM and TEM studies. A study of an alkaline membrane fuel cell (AMFC) operating with hydroxide ion conducting membrane is reported. Evaluation of the fuel cell is performed using membrane electrode assemblies made up of carbon supported platinum (Vulcan XC-72) anode and platinum cathode catalysts and QPSU/ZrO₂ composite membrane. Experimental results indicate that the AMFC employing a cheap non-perflourinated (QPSU/ZrO₂) composite polymer membrane shows better electrochemical performance. The maximum power density observed is 250 mW/cm² for QPSU/10% ZrO₂ at 60 °C. The QPSU/ZrO₂ composite membrane constitutes a good candidate for alkaline membrane fuel cell applications.     

Anion exchange membranes composed of quaternized polybenzimidazole and quaternized graphene oxide for glucose fuel cell

Glucose is one of derivative products from agriculture, possessing high theoretical energy density, non-toxicity and ease of storage, which has been of interest as a fuel in glucose fuel cell. In this work, quaternized polybenzimidazole (Q-PBI) and quaternized graphene oxide (Q-GO) were successfully functionalized by the quaternization between polybenzimidazole (PBI) and 3-bromopropyl trimethylammonium bromide (3-Br), and the reaction between graphene oxide (GO) and dimethyloctadecyl [3(Trimethoxysilyl) propyl]ammonium chloride (DMAOP), respectively. The Q-GOs with various volume fractions were embedded as the dispersed phase in the Q-PBI matrix to produce the Q-GO/Q-PBI composites as an AEM. The 0.5%v/vQ-GO/Q-PBI composite AEM showed the highest hydroxide conductivity of 1.12 ± 0.01 mS cm^?1 at 27 °C, the ion exchange capacity of 1.70 ± 0.03 mmol·g^?1, the water uptake of 66.61 ± 0.57%, and the glucose permeability of (1.79 ± 0.83) × 10^?8 cm²·s^?1. The hydroxide conductivity was higher than the commercial Fumasep® FAB-PK-130 by a factor of 23 times, whereas the glucose permeability was lower by at least an order of magnitude.     

End-group crosslinked hexafluorobenzene contained anion exchange membranes

A kind of anion exchange membranes (AEMs) with CC bond end-group crosslinked structure was synthesized successfully. Unlike the traditional aliphatic AEMs, the AEMs were prepared in this work by a strategy to realize the CC bond thermal end-group crosslinking reaction, exhibiting an obvious microphase separation structure and a suitable dimensional stability. The well-defined ion channels constructed in the AEMs guarantee the fast OH⁻ conduction, as confirmed via physical and chemical characterization. The conductivity was dramatically enhanced due to the effective ion channels and increased ion exchange capacity. Among the as-prepared AEMs, the PHFB-VBC-DQ-80% AEM has a conductivity of 135.80 mS cm⁻¹ at 80 °C. The single cell based on PHFB-VBC-DQ-80% can achieve a power density of 141.7 mW cm⁻² at a current density of 260 mA cm⁻² at 80 °C. The AEMs show good thermal stability verified by a thermogravimetric analyzer (TGA). Furthermore, the ionic conductivity of PHFB-VBC-DQ-80% only decreased by 7.1% after being soaked in a 2 M NaOH solution at 80 °C for 500 h.     

Block copolymer anion exchange membrane containing polymer of intrinsic microporosity for fuel cell application

High hydroxide conductivity and good stability of anion exchange membranes (AEMs) is the guarantee that anion exchange membrane fuel cells (AEMFCs) yield high power output for a long time. Balanced conductivity and stability can be better guaranteed by adopting a relatively low ion exchange capacity (IEC) while reducing the ion transport resistance Herein, a novel block copolymer AEM was designed and synthesized, which contains hydrophobic polymer of intrinsic microporosity (PIM) blocks and hydrophilic, quaternized polysulfone (PSF) blocks. The PIM block imparts high free volume to the membrane so that the resistance of hydroxide ion transport can be reduced; meanwhile, the hydrophilic block can self-assemble more easily to produce a better developed hydrophilic microphase, which may function as efficient channels for hydroxide ion transport. Both transmission electron microscopy images and small-angle X-ray scattering patterns suggested that the resulting AEM possessed a microphase separated morphology. The membrane showed a conductivity of 52.6 mS cm^-l at 80 °C with a relatively low IEC of 0.91 mmol g^?1. It also exhibited a good dimensional stability, swelling ratio maintained almost constant (ca. 17%) at 25 to 80 °C. The assembled H₂/O₂ fuel cell yielded a peak power density of 270 mW cm^?2 at 560 mA cm^?2. Our work demonstrates that incorporation of PIM in an AEM by means of block polymerization is an efficient way of promoting microphase separation and facilitating ion transport.     

Polyaryl piperidine anion exchange membranes with hydrophilic side chain

Recently, the development of high-performance and durable anion exchange membranes has been a top priority for anion exchange membrane fuel cells. Here, a series of polyaryl piperidine anion exchange membranes with hydrophilic side chain (qBPBA-80-OQ-x) are prepared by the superacid-catalyzed Friedel-Crafts reaction. AFM images show that the hydrophilic side chain and hydrophobic main chain form a distinct microphase separation structure. The AEMs of qBPBA-80-OQ-100 and qBPBA-80 have close mechanical strength, but the ionic conductivity of the former (81 mS/cm, 80 °C) is higher than the latter (73 mS/cm, 80 °C). In addition, qBPBA-80-OQ-100 AEM loses by 15.0% after an alkaline treatment of 720 h, while qBPBA-80 AEM loses by 17.8%. The results indicate that the introduction of hydrophilic side chain not only promotes the formation of microphase separation structure, but also improves the ionic conductivity and alkaline resistance of polyaryl piperidine AEMs.     

Synthesis and characterization of long-side-chain type quaternary ammonium-functionalized poly (ether ether ketone) anion exchange membranes

A series of quaternary ammonium salt poly(ether ether ketone) AEMs containing long ether substituents are successfully prepared, and their chemical structure is confirmed by ¹H NMR and FT-IR. The distinct microphase separation morphology of AEMs is observed by TEM. As the content of methylhydroquinone increases, the ion conductivity of AEMs gradually increases. When the content of methylhydroquinone increases to 80%, the hydroxide conductivity of PEEK-DABDA-80 membrane reaches 0.052 S/cm at 80 °C. Meanwhile, it exhibits excellent mechanical properties and anti-swelling ability, with tensile strength of 25 MPa, elongation at break of 8.12% and swelling ratio is only 17.4% at 80 °C. And AEMs also display the better thermal stability. After soaked in 1 M NaOH at 60 °C for 30 days, PEEK-DABDA-80 membrane shows acceptable ion conductivity of 0.021 S/cm at 60 °C. In view of these properties, PEEK-DABDA-x AEMs may display potential application as alkaline AEMs.     

Novel self-cross-linked multi-imidazolium cations long flexible side chains triblock copolymer anion exchange membrane based on ROMP-type polybenzonorbornadiene

A novel benzonorbornadiene derivative (BenzoNBD-Bis(Im⁺Br⁻-Im⁺I⁻)) grafted by multi-imidazolium cations side-chains combined the rigid alkyl spacer and flexible alkoxy spacer is designed and synthesized. Then, the BenzoNBD-Bis(Im⁺Br⁻-Im⁺I⁻) monomer is copolymerized with the epoxy functionalized norbornene monomer (NB-MGE) and norbornene (NB) via ring-opening metathesis polymerization (ROMP) using Grubbs 3rd catalyst. All as-designed triblock copolymer membranes (TBCMs) show a thermal decomposition temperature beyond 310 °C and can well be dissolved in common organic solvents. The self-cross-linked structure of anion exchange membrane (AEM) is confirmed by gel fraction and tensile measurement. The water uptake and swelling ratio of TBCMs and AEMs are also measured. Major properties required for AEMs such as ion exchange capacity (IEC), hydroxide conductivity and alkaline stability are investigated. AEM-9.09 shows a hydroxide conductivity of 100.74 mS cm⁻¹ at 80 °C. Besides, the micro-phase separated morphology of AEM is confirmed by TEM, AFM and SAXS analyses, AEMs formed distinct micro-phase separation. The as-prepared AEM exhibits a peak power density of 174.5 mW cm⁻² at 365.1 mA cm⁻² tested in a H₂/O₂ single-cell anion exchange membrane fuel cell (AEMFC) at 60 °C. The newly developed strategy of self-cross-linked multi-imidazolium cations long side-chains triblock benzonorbornadiene copolymer provides an effective method to develop high-performance AEMs.     

A novel quaternized poly(ether sulfone) membrane for alkaline fuel cell application

A new type of poly(ether sulfone)‐based self‐aggregated anion exchange membrane (AEM) was successfully synthesized and used in H₂/O₂ fuel cell applications. The self‐aggregated structural design improves the effective mobility of OH^? ion and increases the ionic conductivity of AEM. Proton nuclear magnetic resonance and Fourier transform infrared spectroscopy spectra confirm successful chloromethylation and quaternization in the poly(ether sulfone). Thermogravimetric analysis curves show the self‐aggregated membrane was thermally stable up to 180 °C. The AEM also has excellent mechanical properties, with tensile strength 53.5 MPa and elongation at break 47.6% under wet condition at room temperature. The performance of H₂/O₂ single fuel cell at 30 °C showed the maximum power density of 162 mW cm^?2. These results show that the self‐aggregated quaternized poly(ether sulfone) membrane is a potential candidate for alkaline fuel cell applications. Copyright © 2014 John Wiley & Sons, Ltd.     

Highly alkaline stable fully-interpenetrating network poly(styrene-co-4-vinyl pyridine)/polyquaternium-10 anion exchange membrane without aryl ether linkages

To avoid the detrimental effect of aryl ethers on the alkali stability of anion exchange membrane (AEM), elaborately designed and synthesized poly(styrene-co-4-vinyl pyridine) (PS4VP) copolymer without aryl ether linkages is used to prepare AEMs. By introducing commercialized polyquaternium-10 (PQ-10) as the main ion-conducting molecule, the fully-interpenetrating polymer network quaternized PS4VP/PQ-10 (F-IPN QPS4VP/PQ-10) AEMs are prepared by cross-linking PS4VP and PQ-10, respectively. The as-prepared F-IPN QPS4VP/PQ-10 AEMs have obvious nanoscale microphase-separated morphologies, which ensure the membranes have good mechanical properties and dimensional stability. With optimized component ratios, F-IPN QPS4VP/PQ-10 AEM exhibits high ionic conductivity (74.29 mS/cm at 80 °C) and power density (111.83 mW/cm² at 60 °C), as well as excellent chemical stabilities (94.36% retaining of initial mass after immersion in Fenton reagent at 30 °C for 10 days, and 92.28% retaining of original ionic conductivity after immersion in 1 M NaOH solution at 60 °C for 30 days), which are greater than those of semi-interpenetrating polymer network QPS4VP/PQ-10 AEM. In summary, a combination of fully-interpenetrating polymer network and stable polymer chains and ion-conducting moieties is found to effectively overcome the trade-off between high ionic conductivity and good dimensional/chemical stabilities.     

Poly(isatin-piperidinium-terphenyl) anion exchange membranes with improved performance for direct borohydride fuel cells

In this work, an effective design strategy for anion exchange membranes (AEMs) incorporating ether-bond free and piperidinium cationic groups promote chemical stability. A series of poly (isatin-piperidium-terphenyl) based AEMs were synthesized by superacid catalyzed polymerization reaction, followed by quaternization. The effect of functionalization on the performance of poly (isatin-N-dimethyl piperidinium triphenyl) (PIDPT-x) AEMs was investigated. Highly reactive N-propargylisatin was introduced into the backbone to achieve high molecular weight polymers (η_a = 2.06–3.02 dL g⁻¹) leading to robust mechanical properties, as well as modulating 1.78–2.00 mmol g⁻¹ of the ion exchange capacity (IEC) of the AEMs by feeding. Apart from that, the rigid non-ionized isatin-terphenyl segment provides AEMs improved dimensional stability with a swelling ratio of less than 12% at 80 °C. Among them, PIDPT-90 exhibited a higher OH⁻ conductivity of 105.6 mS cm⁻¹ at 80 °C. The alkali-stabilized PIDPT-85 AEM was presented, in which OH⁻ conductivity retention maintained 85.6% in a 2 M NaOH at 80 °C after 1632 h. Afterward, the direct borohydride fuel cells (DBFC) with PIDPT-90 membrane as a separator showed an open-circuit voltage of 1.63 V and a peak power density of 75.5 mWcm⁻² at 20 °C. This work demonstrates the potential of poly (isatin- N-dimethyl piperidinium triphenyl) as AEM for fuel cells.     

Novel poly(carbazole-butanedione) anion exchange membranes constructed by obvious microphase separation for fuel cells

To develop anion exchange membranes with excellent chemical stability and high performance. A series of quaternary ammonium functionalized (hydrophilic) hydrophobic rigid poly (carbazole-butanedione) (HOCB-TMA-x) anion exchange membranes were prepared, where x represents the percentage content of hydrophobic unit octylcarbazole (OCB). Due to the introduction of hydrophobic rigid unit octylcarbazole and hexyl flexible side chain, the hydrophilic-hydrophobic microstructure of AEMs was developed. The AEMs exhibit excellent overall performance, specifically the low swelling ratio HOCB-TMA-30 membrane exhibits the highest OH^? conductivity of 152.9 mS/cm at 80 °C. Furthermore, the ionic conductivity of AEM decreased by only 9.5% after 2250 h of immersion in 1 M NaOH. The maximum peak power density of a single cell with a current density of 4.38 A/cm² at 80 °C was 1.85 W/cm².     

Mussel-inspired strategy towards functionalized reduced graphene oxide-crosslinked polysulfone-based anion exchange membranes with enhanced properties

Chemical crosslinking is regard as an effective method to balance the ionic conductivity and dimensional stability of anion exchange membranes (AEMs). In this work, a series of crosslinked AEM composite membranes based on polydopamine-functionalized reduced graphene oxide (PDArGO) were constructed from quaternized polysulfone (QPSU) with amino groups via mussel-inspired chemistry strategy. On the one hand, as the dopant, the hydrogen bonding interaction between PDArGO and a large number of amino groups on the side chains of QPSU can enhance the water uptake of the membranes and has a positive influence on the ionic conductivity of composite membranes. On the other hand, PDArGO also acts as the crosslinker, which can form a micro-crosslinked structure with the amino groups on the side chains of the polymer through the Michael addition/schiff base reactions. Under the combined influence of the above two factors, the crosslinked composite AEMs exhibited special delightful properties. In general, the crosslinking reaction will lead to the decrease of the ionic conductivity of the membranes, but as for the membranes prepared by us, the ionic conductivity had been improved to some extent. Especially, the QPSU-1.5%-PDArGO exhibited 57% improvement in the hydroxide conductivity than that of pure QPSU membrane and reached the highest value of 61 mS cm^?1 at 80 °C. Besides, the crosslinked membranes also exhibited strong dimensional stability, good mechanical strength, comparable alkaline stability and improved methanol permeability.     

Facile construction of poly(arylene ether)s-based anion exchange membranes bearing pendent N-spirocyclic quaternary ammonium for fuel cells

Anion exchange membrane (AEM) fuel cells have received significant attention due to their low fuel permeability and the use of non-platinum catalysts. However, the development of AEMs with robust chemical stability and high conductivity is still a great challenge. Herein, we prepare a new type of partially fluorinated backbone bearing pendent N-spirocyclic quaternary ammonium (QA) cations via a facile Williamson reaction, which displays great potential for fuel cells. The integration of the two substructures (a fluorinated moiety into a polymer backbone and a pendent cation structure) is beneficial for the fabrication of a well-defined micro-phase separation structure, thereby facilitating the construction of a highly-efficient ion transporting pathway. Correspondingly, the resulting AEM (PAENQA-1.0), despite its a relatively low ionic exchange capacity (0.93 meq g⁻¹) demonstrates a conductivity of 63.1 mS cm⁻¹ (80 °C). Meanwhile, the constrained ring conformation of N-spirocyclic QA results in improved stability of the AEMs.     

Cross-linked anion exchange membranes with flexible,long-chain,bis-imidazolium cation cross-linker

Herein, poly (phenylene) oxide (PPO)-based cross-linked anion exchange membranes (AEMs) with flexible, long-chain, bis-imidazolium cation cross-linkers are designed and synthesized. Although the cross-linked membranes possess high ion exchange capacity (IEC) values of up to 3.51–3.94 meq g⁻¹, they have a low swelling degree and good mechanical strength because of their cross-linked structure. Though the membranes with the longest flexible bis-imidazolium cation cross-linker (BMImH-PPO) possess the lowest IEC among these PPO-based AEMs, they show the highest conductivity (24.10 mS cm⁻¹ at 20 °C) and highest power density (325.7 mW cm⁻² at 60 °C) because of the wide hydrophilic/hydrophobic microphase separation in the membranes that promote the construction of ion transport channels, as confirmed by atom force microscope (AFM) images and the small angle X-ray scattering (SAXS) analyses. Furthermore, the BMImH-PPO samples exhibit good chemical stability (10% and 6% decrease in IEC and conductivity, respectively, in 2 M KOH at 80 °C for 480 h, and a 22% decrease in weight in Fenton's reagent at 60 °C for 120 h), making such cross-linked AEMs potentially applicable in alkaline anion exchange membrane fuel cells.     

Mechanically robust semi-interpenetrating polymer network via thiol-ene chemistry with enhanced conductivity for anion exchange membranes

Anion exchange membranes (AEMs) have emerged as crucial functional materials in various electrochemical device, such as fuel cell. Both the mechanical property and ionic conductivity play important roles in AEMs. Herein, a series of semi-interpenetrating polymer network AEMs are prepared by introducing flexible polyvinyl alcohol to the rigid photo-crosslinked poly (2,6-dimethyl-1,4-phenylene oxide) network. Such strategy endows AEM with tunable composition and mechanical property. Among these AEMs, membrane with an IEC of 1.46 mmol/g shows the highest mechanical strength of 30.8 MPa and a relatively lower swelling ratio, as well as the highest hydroxide conductivity. Importantly, the alkaline stability of these AEMs has been improved, 66.5% of the hydroxide conductivity is maintained after treatment in 1 M NaOH at 80 °C for 1000 h. Tentative assembly of H₂/O₂ fuel cell at 60 °C with this AEM displays a peak power density of 78 mW/cm². All the results demonstrate that sIPN structure is a promising way to enhance the mechanical property, ionic conductivity, and the alkaline stability of AEMs for the future application in AEMFCs.     

Partially crosslinked comb-shaped PPO-based anion exchange membrane grafted with long alkyl chains: Synthesis,characterization and microbial fuel cell performance

Anion exchange membranes (AEMs) with higher ion exchange capacities (IECw) are limited to applications due to excessive swelling and higher water uptake. Crosslinked macromolecular structures have been a strategy to balance between ionic conductivity and swelling in membranes. However, highly crosslinked AEMs are usually mechanically brittle and poorer in ion transport. Thus we report a series of partially diamine crosslinked (X = 10%, 15%, 20%) comb-shaped AEMs functionalized with dimethylhexadecylammonium groups exhibiting improved flexibility, water uptake and swelling properties over conventional un-crosslinked or fully crosslinked materials. The higher conductivities in these PPO AEM(X) (for example, X = 20%, IECw = 1.96 mmol/g, σ(OH⁻) ~ 67 mS/cm at 80 °C) are attributed to the distinct nanophase separation as observed in SAXS and AFM analyses. Finally, the microbial fuel cell performances of the membranes were compared with commercially available cation and anion exchange membranes.