Performance Of Anion Exchange Membranes Research Articles

Non-precious high entropy alloys and highly alkali-resistant composite membranes based high performance anion exchange membrane water electrolyzers

Cost-effective highly efficient and stable catalysts and alkali-resistant anion exchange membranes (AEMs) are critical for practical applications of anion exchange membrane water electrolyzers (AEMWEs). Here, bifunctional non-precious FeCoNiCuMo high entropy alloys (HEAs), electrochemically deposited on nickel mesh as an anode (FeCoNiCuMo/NM) and on carbon paper as a cathode (FeCoNiCuMo/CP), together with a NiFe layered double hydroxide (LDH) loaded AEM (AEM/LDH), were developed for high performance AEMWEs. The AEMWE thus fabricated delivered an ultrahigh current density of 1777 mA cm−2 at 2 V and exhibited remarkable stability with a less than 0.1% cell voltage increase after a 100-hour operation at 100 mA cm−2 at 50 °C, largely outperforming those of the precious metal based AEMWE, composed of IrO2/NM as the anode and Pt/C/CP as the cathode, 1231 mA cm−2@2 V and 4.57% increase in cell voltages. Composition of the alkali-resistant, hydrophilic, and water electrolysis active NiFe LDH into the AEM improved not only the electrolyte uptake and operational stability, but also the efficiency of the AEMWE, with a 10% boost in current density achieved at 2 V and a reduction in cell voltage increases from 2.94% to 0.0951%. The present development demonstrates the practicality of AEMWEs toward green hydrogen production.

Suppression of current-induced membrane discharge of bipolar membranes by regulating ion crossover transport

Bipolar membranes (BPMs) exhibit the unique capability to regulate the operating environment of electrochemical system through the water dissociation-combination processes. However, the industrial utilization of BPMs is limited by instability and serious energy consumption. The current-induced membrane discharge (CIMD) at high-current conditions has a negative influence on the performance of anion-exchange membranes, but the underlying ion transport mechanisms in the BPMs remain unclear. Here, the CIMD-coupled Poisson-Nernst-Planck (PNP) equations are used to explore the ion transport mechanisms in the BPMs for both reverse bias and forward bias at neutral and acid-base conditions. It is demonstrated that the CIMD effect in the reverse-bias mode can be suppressed by enhancing the diffusive transport of salt counter-ions (Na+ and Cl−) into the BPMs, and that in the forward-bias mode with acid-base electrolytes can be suppressed by matching the transport rate of water counter-ions (H3O+ and OH−). Suppressing the CIMD can promote the water dissociation in the reverse-bias mode, as well as overcome the plateau of limiting current density and reduce the interfacial blockage of salt co-ions (Cl−) in the anion-exchange layer in the forward-bias mode with acid-base electrolytes. Our work highlights the importance of regulating ion crossover transport on improving the performance of BPMs.

Polycyclic norbornene based anion-exchange membranes with high ionic conductivity and chemical stability

Polycyclic norbornene derivatives, dicyclopentadiene (DCPD) and tricyclopentadiene (TCPD), have rigid structures with ease of accessibility and high chemical reactivity. After vinylic-addition polymerization, the resultant polynorbornenes (PNBs) possess high thermal stability, excellent mechanical integrity, and chemical inertness due to the retention of the rigid polycyclic norbornene motifs along the polymer backbones. Herein, we first report polycyclic PNBs composing DCPD or TCPD and an alkyl-bromide-substituted norbornene as comonomers to prepare high performance anion-exchange membranes (AEMs). The two double bonds in DCPD/TCPD can be used for vinylic-addition polymerization and thiol-ene click cross-linking reactions, respectively. By comparing with previously reported cross-linked PNB AEMs without polycyclic structures, it is unambiguously confirmed that the involvement of DCPD/TCPD significantly improved the mechanical strength (the stress-at-break of 34 MPa vs 28 MPa), the hydroxide conductivity (212 mS cm−1vs 199 mS cm−1 at 90 °C), and the alkaline stability (93 % vs 81 % conductivity remaining after treating in 1 M KOH at 80 °C for 1200 h). The successful application of the AEMs with excellent durability for over 500 h prove that the involvement of polycyclic structures is a convenient strategy to enhance the performance of aromatic-free AEMs.

A novel side‐chain type double‐cation grafted poly (binaphthyl triphenyl piperidine) membranes for anion exchange membrane fuel cells

Recent advancements in anion exchange membrane fuel cells (AEMFCs) have been primarily driven by improvements in anion exchange membranes (AEMs). Aryl ether bond‐free membranes have emerged as a promising avenue for enhancing the performance of AEMs. In this study, a novel side‐chain polymer, PBTP‐s‐x, possesses double cationic groups, aiming at further enhancing overall performance for AEMs. The use of a twisted stereospecific backbone structure of polymerized binaphthyl and triple biphenyl monomer and grafted side chains of piperidine cationic groups not only improves the microphase separation structure of the membrane, but also improves the alkali resistance. Notably, the PBTP‐s‐100 AEMs exhibit exceptional OH‐ conductivity, reaching up to 138.21 mS cm‐1, and show outstanding mechanical properties with a tensile strength of up to 28 MPa. Additionally, PBTP‐s‐100 displays excellent durability, proved by the NMR spectral consistency and over 80% ion conductivity retention in 1 M NaOH at 60°C for 4 weeks. And PBTP‐s‐100 exhibits a higher Lowest Unoccupied Molecular Orbital (LUMO) and a larger energy gap for LOMO and Highest Occupied Molecular Orbital (HOMO) by density functional theory calculation, which indicates it possesses sterling alkaline stability. These findings highlight the potential of PBTP‐s‐100 as a highly performing polymer structure suitable for AEM.

Recent Advances and Challenges in Anion Exchange Membranes Development/Application for Water Electrolysis: A Review.

In recent years, anion exchange membranes (AEMs) have aroused widespread interest in hydrogen production via water electrolysis using renewable energy sources. The two current commercial low-temperature water electrolysis technologies used are alkaline water electrolysis (AWE) and proton exchange membrane (PEM) water electrolysis. The AWE technology exhibited the advantages of high stability and increased cost-effectiveness with low hydrogen production efficiency. In contrast, PEM water electrolysis exhibited high hydrogen efficiency with low stability and cost-effectiveness, respectively. Unfortunately, the major challenges that AEMs, as well as the corresponding ion transportation membranes, including alkaline hydrogen separator and proton exchange membranes, still face are hydrogen production efficiency, long-term stability, and cost-effectiveness under working conditions, which exhibited critical issues that need to be addressed as a top priority. This review comprehensively presented research progress on AEMs in recent years, providing a thorough understanding of academic studies and industrial applications. It focused on analyzing the chemical structure of polymers and the performance of AEMs and established the relationship between the structure and efficiency of the membranes. This review aimed to identify approaches for improving AEM ion conductivity and alkaline stability. Additionally, future research directions for the commercialization of anion exchange membranes were discussed based on the analysis and assessment of the current applications of AEMs in patents.

Tuning polar discrimination between side chains to improve the performance of anion exchange membranes

Anion exchange membranes (AEMs) are the heart of alkaline fuel cells and water electrolysis, and have made a great progress in recent years. However, AEMs are still unable to satisfy the needs of high conductivity and stability, hindering their widespread commercialization. Side chain regulations have been widely used to prepare highly conductive and durable AEMs. Here, we construct a series of polyaromatic AEMs grafted with fluorinated cation side chains and cation-free alkyl chains with different end groups to explore the polar discrimination of side chains on membrane performance. This work demonstrates that AEMs grafting the cation side chains with superhydrophobic fluorine pendent and alkyl side chains with hydrophilic pendent enhance water content and ion conductivity. This is due to the strong immiscibility between the hydrophilic and hydrophobic head groups which promotes the establishments of microphase separation and ion highways. Specifically, poly(binaphthyl-co-terphenyl piperidinium) containing fluorinated piperidinium side chains and alkyl chains with methoxy pendent (QBNTP-QFM) possesses a satisficed OH− conductivity (170.6 mS cm−1 at 80 °C) and can tolerate 5 M hot NaOH for 2100 h with only 3.4 % conductivity loss. Expectedly, the single cell with QBNTP-QFM yields a prominent maximum power density of 1.62 W cm−2 and the water electrolysis cell with QBNTP-QFM achieves a pronounced current density of 3.0 A cm−2 at 1.8 V, both cells also display a prominent durability for 120 h operation. The results prove that this side chain optimization can improve ion conductivity and is a promising method for AEM development.

Intrinsic microporous poly(phenyl-alkane)s with pendent piperazinium for high performance anion exchange membrane fuel cells

Exploring anion exchange membranes (AEMs) with high conductivity and satisfactory stability is very meaningful for the advancement of alkaline fuel cells. Herein, a novel class of intrinsic microporous AEMs with pendent piperazinium are systematically fabricated for alkaline fuel cell performance testing. Contorted and rigid spirobisindane backbone structure expands the free volume of AEMs, inducing broad and interconnected ion transport channels. This unique feature endows membranes a leading advantage for the efficient transmission of hydroxide ions. Consequently, the prepared membrane displays excellent normalized hydroxide conductivity of 78.99 mS g cm−1 mmol−1 at 80 °C. Meanwhile, the hydroxide conductivity degrades by only 8.3 % after treatment in 1 M NaOH for 1000 h at 80 °C. Moreover, the peak power density of H2/O2 single cell employing this membrane exhibits 1.06 W cm−2 at 80 °C and the cell can preserve 93.0 % of its initial voltage after operating for 18 h.

Constructing blocked-nanolayer by surface charge inversion over anion exchange membrane for improved antifouling performance

Anion exchange membranes (AEMs) with excellent antifouling property are essential for treating highly saline organic wastewater through electrodialysis (ED). In this study, we proposed a strategy of surface charge inversion to construct a blocked- nanolayer based on in-suit dopamine (DA) deposition followed by grafting negative-charged 2-acrylamide-2-methylpropanesulfonic acid (AMPS) for promoting the antifouling performance of AEM. It's indicated that the surface hydrophilicity and negative charge density was gradually enhanced with the increase of AMPS grafting density without sacrifices of ion exchange capability, swelling ratio and desalination performance. In the simulated fouling experiments, the optimal AEM-AMPS-105 membrane exhibited excellent antifouling property due to the improved surface hydrophilicity and high electrostatic repulsion against organic matter. It's highlighted that the transmembrane voltage of modified membrane after operating 200 min was reduced from 7.12 V to 4.85 V with a significant decrease of energy consumption by 55.1 % while maintaining a high current efficiency level of 85.5 %. Moreover, the modified membrane performed significantly enhanced salt/contaminant selectivity and high stability in dye wastewater treatment. We anticipated that the construction of charge-blocked nanolayer by surface charge inversion offered a practical method for improving the organic fouling-resistance of AEMs.

Twisted Poly(p-terphenyl-co-m-terphenyl)-Based Anion Exchange Membrane for Water Electrolysis.

In order to improve the mechanical and water electrolysis performance of anion exchange membranes (AEMs), we adjusted the ratio between p-terphenyl and m-terphenyl to balance the backbone conformation, which gives it a better suitability for a better combination with cations. The results showed that poly(m-terphenyl-co-p-terphenyl)-based AEMs have excellent mechanical properties. Among them, the m-p-TP-40-BOP-ASU membrane has the highest tensile strength and elongation at break (75.72 MPa and 16.07%). The ionic conductivity reaches 137.14 mS cm-1 at 80 °C owing to the fact that efficient ion-conducting channels are formed by well-balanced molecular structures. The current density of the m-p-TP-40-BOP-ASU membrane reached 1.96 A cm-2 (1 M KOH aq, 2.0 V and 60 °C). After testing for 112 h under a current density of 500 mA cm-2, the voltage increased by 102 mV compared to the initial electrolysis voltage. All results have shown that m-p-TP-x-BOP-ASU has excellent electrolysis performance and electrochemical durability and has a promising application prospect in AEM water electrolyzers.

Comb-shaped anion exchange membrane with segmented hydrophilic/hydrophobic side chain

A flexible hydrophilic chain segment with ether bonds and a long hydrophobic tail chain with multiple carbon atoms are designed and grafted on the same side of the polymer backbone, which can not only improve the alkaline stability by preventing the benzyl carbon from being attacked by OH-, but also reduce the hydration degree of the membrane, giving it excellent conductivity, alkaline stability and low swelling ratio. These results show that the prepared anion exchange membranes (AEMs) with a hydrophilic chain segment containing 2 ether bonds exhibits the best overall performance. Its ionic conductivity can reach 90.4 mS cm−1 at 80 °C, the swelling ratio is less than 8%, the tensile strength can reach 14.5 MPa, and the elongation at break is 79.0%. Even after being soaked under alkaline conditions for 672 h, the conductivity of the original membrane still remains over 85%. The peak power density of the fuel cell using this AEM can reach as high as 582 mW cm−2. The segmented hydrophilic and hydrophobic side chain proposed in this work provides a novel idea to design the AEM materials and improve the performance of anion exchange membrane fuel cell.

A novel anion exchange membrane comprised of three aromatic units for fuel cells

Anion exchange membrane fuel cell (AEMFC) has made great progress recently due to the continuous improvement of anion exchange membrane (AEM). Aryl ether bond-free membranes are considered to be promising for improving the overall performance of AEMs. Here, we present a copolymer consisting of m-terphenyl, diphenyl ethane and biphenyl (PMDBP) to further enhance the microphase separation structure by introducing a third structural unit, biphenyl. Meanwhile, the more compact biphenyl structure enhances the mechanical strength of AEMs. Specifically, PMDBP AEMs possess superior OH- conductivity (up to 113 mS cm−1) and excellent mechanical properties (tensile strength up to 42 MPa). Furthermore, the PMDBP has an outstanding single-cell performance with a peak power density (PPD) of up to 95 mW cm−2 with a platinum-carbon (Pt/C) catalyst at 80°C in H2-air. In addition, PMDBP is provided with excellent durability, including NMR spectral consistency and over 90% ion conductivity retention in 1 M NaOH at 60°C for 720 h. This study provided a copolymer structure suitable for anion exchange membrane that can provide excellent performance for fuel cells and electrolyzers.

Synergistic effect and ionic conductivity of crosslinked imidazole ionic liquids and piperidine cations on poly(biphenyl-piperidine) anion exchange membranes

In order to prepare anion exchange membranes with good performance, and we prepared ether-free bonded poly(biphenyl-piperidine) anion exchange membranes (CQPBP-M-x, x is degree of crosslinking) by introducing cross-linked imidazolium ionic liquids. The introduction of cross-linked imidazolium ionic liquids increases multiple OH− transport sites and establishes a more pronounced microphase-separated structure with the backbone, while acting synergistically with piperidinium cations, resulting in improved membrane conductivity. Meanwhile, the introduction of an ether-free backbone and the construction of a cross-linked structure could promote the chemical stability of the membrane and effectively inhibit membrane swelling. The prepared cross-linked imidazole ionic liquid poly(biphenyl-piperidine) (CQPBP-M-30 %) membrane exhibited relatively good ionic conductivity (88.03 mS/cm), and low swelling (11.75 %) at 80 °C. The H2–O2 fuel cell performance test conducted at 80 °C without back pressure showed a peak power density of 125.7 mW/cm2. Therefore, it is a worthwhile direction to explore to improve the performance of anion exchange membranes by adopting an ether-free backbone and constructing a cross-linked structure contain multiple cationic groups.

Improving the Durability and Performance of Anion Exchange Membranes for Water Electrolyzers

The two major drawbacks of most renewable sources are intermittency and availability. Renewables will naturally need to be efficiently integrated with electrochemical methodologies for storage (batteries), conversion (fuel cells) and application (electrolysis, CO2 reduction reactions). Alkaline anion exchange membranes (AAEM) have attracted considerable interest to navigate some of the economic hurdles native to polymer electrolyte membrane-based technologies. Despite many advances over the past decade, AAEM long-term stability towards hydroxide mediated degradation remains a significant challenge. Here we integrate anion exchange membrane synthesis, accelerated stress testing and characterization (structural, chemical, electrochemical) to understand and mitigate the effect of degradation of AAEM under electrochemical conditions on the performance of these materials.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 21-ERD-013. IM # LLNL-ABS-846373

(Poster Award - Honorable Mention) Durable Polybenzimidazole Anion Exchange Membranes for Alkaline Water Electrolyzers

Water electrolysis under alkaline conditions allows the use of inexpensive non-platinum-group catalysts such as nickel.1, 2 Conventional alkaline electrolyzers usually employ a highly concentrated aq. KOH solution as electrolyte (5-7 M) with a porous diaphragm as separator. Alternatively, protolysable polymers such as polybenzimidazole (PBI) may be swollen with electrolyte and used as ion-solvating membranes.2, 3 However, the chemical stability of the polymers can become a serious issue under these harsh conditions. Operation under more dilute conditions, e.g., up to 2 M KOH, may bring the benefits of the alkaline conditions combined with a longer cell lifetime. Under these conditions, aliphatic cyclic quaternary ammonium (QA) cations, such as piperidinium, have shown excellent stability.In the present work, performed as part of the EU project “NEXTAEC”, we have designed and synthesized m-PBI grafted with mono- and bis-piperidinium functionalized side chains, respectively (Figure 1a-b). AEMs were prepared from polymers with varying ion exchange capacities and studied at 80 °C containing KOH solutions in the concentration range 0.5-2 M KOH. The membranes were characterized with respect to, e.g., electrolyte solution uptake, alkaline stability, and electrolyser performance (Figure 1c). The uptake showed a strong inverse correlation with KOH concentration, which also affected the electrochemical performance. The stability as evaluated by 1HNMR spectroscopy was excellent showing, in the worst case, less than 8 % ionic loss after 6 months storage in 2 M KOH at 80 °C. Li, D.; Park, E. J.; Zhu, W.; Shi, Q.; Zhou, Y.; Tian, H.; Lin, Y.; Serov, A.; Zulevi, B.; Baca, E. D.; Fujimoto, C.; Chung, H. T.; Kim, Y. S., Highly quaternized polystyrene ionomers for high performance anion exchange membrane water electrolysers. Nature Energy 2020, 5 (5), 378-385.Aili, D.; Kraglund, M. R.; Rajappan, S. C.; Serhiichuk, D.; Xia, Y.; Deimede, V.; Kallitsis, J.; Bae, C.; Jannasch, P.; Henkensmeier, D.; Jensen, J. O., Electrode Separators for the Next-Generation Alkaline Water Electrolyzers. ACS Energy Letters 2023, 8 (4),1900-1910.Aili, D.; Yang, J.; Jankova, K.; Henkensmeier, D.; Li, Q., From polybenzimidazoles to polybenzimidazoliums and polybenzimidazolides. Journal of Materials Chemistry A 2020, 8 (26), 12854-12886.Marino, M. G.; Kreuer, K. D., Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids. ChemSusChem 2015, 8 (3), 513-23. Figure 1

N-Methylquinuclidinium-Based Anion Exchange Membrane with Ultrahigh Alkaline Stability.

Anion-exchange-membrane (AEM) water electrolysis is a promising technology for hydrogen production from renewable energy sources. However, the bottleneck of its development is the poor comprehensive performance of AEM, especially the stability at highly concentrated alkaline condition and temperature. Herein, a new cationic group N-methylquinuclidinium with enhanced alkaline stability is proposed and hereby a full-carbon chain poly(aryl quinuclidinium) AEM is prepared. Compared with reported AEMs, it shows ultrahigh comprehensive alkaline stability (no chemical decomposition, no decay of conductivity) in 10m NaOH aqueous solution at 80°C for more than 1800h, excellent dimensional stability (swelling ratio: <10% in pure water, <2% in 10m NaOH) in OH- form at 80°C, high OH- conductivity (≈139.1mScm-1 at 80°C), and high mechanical properties (tensile strength: 41.5MPa, elongation at break: 50%). The water electrolyzer using the AEM exhibits a high current density (1.94Acm-2 at 2.0V) when assembled with nickel-alloy foam electrodes, and high durability when assembled with nickel foam electrodes.

Composite modification of anion exchange membrane by in-situ layer-by-layer assembly to improve antifouling performance

A novel composite modified strategy by in-situ layer-by-layer (LBL) assembly was proposed to improve antifouling performance of anion exchange membrane (AEM) without requiring disassembling the membrane stack. In this approach, the modified layer consisting of (poly (sodium 4-styrene sulfonate) (PSS) and dopamine (DA))/(polyethylene imine (PEI) and DA) was alternately constructed on the AEM surface via reversal electrodeposition. The in-situ LBL assembly modified layer not only contained more hydrophilic and negatively charged groups, but also contained more covalent bonding structures due to copolymerization between PEI and DA. As a result, the in-situ LBL assembly five layers composite modified membrane stack (Co-5Layer) had the optimal antifouling performance with alkaline stability, and it had no discernible effect on the desalination performance. Meanwhile, the effect of sodium dodecylbenzene sulfonate on the ion transmembrane migration was revealed by in-situ electrochemical impedance spectroscopy tests. This work provided a new idea of overcoming AEM fouling through in-situ surface modification.

Pyrrolidinium-functionalized Cardo (TPM) poly(arylene ether sulfone)s membranes for acid recovery: The effects of Cardo (TPM) microstructures

To explore the intrinsic correlation between the rigidity and distortion degree of polymer backbones and the diffusion dialysis (DD) performance of anion exchange membranes (AEMs), pyrrolidinium-functionalized poly(arylene ether sulfone)s containing different Cardo (TPM) moieties were prepared. The structures, properties and DD performance of above AEMs were systematically evaluated. As the Cardo (TPM) group angle increased, the d-spacing, fractional free volume, and membrane area resistance increased, and the microphase separation structures, hydrophilicity, and acid flux decreased, mainly because larger Cardo (TPM) group angles are unfavourable for the close packing of polymer chains in space. Both the Cardo-type and TPM-type AEMs exhibited universal ultrahigh H+/Fe2+ selectivity (S > 3819), which was mainly attributed to the synergistic influence of their rigid narrow ion transport channels, small pore diameter (0.48–0.62 nm) and narrow pore size distribution (0.24–0.68 Å). Additionally, due to the high-density amide groups of TPM units, which decreased the hydrophobicity of the polymer skeleton and induced the formation of an additional transport pathway for Fe2+ through hydrogen bonding interactions, the TPM-type AEMs showed both lower acid flux and selectivity, suggesting that the structure of hydrophilic auxiliary groups should be carefully designed when improving the DD performance of AEMs.

Fundamental Insight into Phenyl-Free Polynorbornene Ionomers Enables High Performance Anion Exchange Membrane Fuel Cells

Anion exchange membrane fuel cells (AEMFCs) are seen as a possible successor to proton exchange membrane fuel cell technologies. A major motivation behind AEMFC development is the potential to use less costly materials, such as non-platinum group metal catalysts, thus reducing the stack cost. Anion exchange ionomers (AEIs) are polymers that facilitate ion transport in the catalyst layer play and a critical role in the performance of fuel cells. In fact, cell performance is profoundly affected by fundamental interactions between the catalyst surface and the AEI. Two such interactions are of particular importance: phenyl adsorption on hydrogen oxidation catalysts and electrochemical oxidation of phenyl moieties on oxygen evolution catalysts. Both are detrimental to an alkaline device’s performance and durability.We compared the adsorption energy of phenyl-containing ionomers for implementing phenyl-free ionomers. Density functional theory calculations indicated that the norbornane fragment has minimal adsorption energy on Pt(111) due to the absence of aromatic electrons. A soluble quaternized polynorbornene ionomer was prepared by vinyl addition polymerization. This ionomer enables high performance in fuel cells, (peak power density > 2 W cm-2), proving the advantage of the phenyl-free structure. This study establishes the phenyl adsorption energy-electrode performance relationship, highlighting the importance of material interactions between the catalysts and ionomers.

Cross-Linked Anion Exchange Membranes for Non-Aqueous Redox Flow Battery

The development of redox flow batteries (RFBs) has been one of the primary responses to the need to store harvested renewable energy for improving grid reliability and utilization.1–6 In this study, we synthesized and characterized different Bromobutyl Norbornene backbone-based anion-exchange membranes (AEM) with different Tetramethyl hexadiamine crosslinker amounts and explored the performance of AEMs in non-aqueous redox flow batteries under ideal conditions. Performance was compared based on high stability in a non-aqueous solvent, high permeability to the charge-carrying ion, low electric cell resistance, low cross-over of the redox-active molecules, high mechanical property, and low cost. 100 cycles battery data indicates that Bromobutyl Norbornene-based AEM performance is far better than the commercial best membrane Fuma-375. The best membrane will be found which will show no cross-over of redox-active electrolytes after 1000 battery cycle experiments and exhibit low resistance and high structural/chemical stability in MeCN solvent. References (1) Mazumder, Md. M. R.; Burton, A.; Richburg, C. S.; Saha, S.; Cronin, B.; Duin, E.; Farnum, B. H. Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate. Inorg. Chem. 2021, 60 (17), 13388–13399. https://doi.org/10.1021/acs.inorgchem.1c01699.(2) Mazumder, M. M. R.; Farnum, B. H. Two One Electron vs One Two-Electron Redox System of Nickel Diethyldithiocarbamate for Redox Flow Battery; ACS, 2021. https://doi.org/10.1021/scimeetings.1c00951.(3) Mazumder, M. M. R. Ni(IV/II) Redox Couple 2e- Reversibility Improvement for Redox Flow Battery. ECS Meet. Abstr. 2021, MA2021-02 (5), 1855–1855. https://doi.org/10.1149/ma2021-0251855mtgabs.(4) Islam, R.; Mazumder, M. M. R.; Farnum, B. H. Solvent Dependent Spectroscopic and Electrochemical Studies of Nickel (II) Diethyldithiocarbamate for Energy Storage. ECS Meet. Abstr. 2021, MA2021-01 (1), 54–54. https://doi.org/10.1149/ma2021-01154mtgabs.(5) Rahaman Mazumder, M. M.; Islam, R.; Khan, M. A. R.; Anis‐Ul‐Haque, K. M.; Rahman, M. M. Efficient AcFc‐[Fe III (Acac) 3 ] Redox Couple for Non‐aqueous Redox Flow Battery at Low Temperature. Chem. – Asian J. 2023, 18 (1). https://doi.org/10.1002/asia.202201025.(6) Mazumder, Md. M. R.; Dalpati, N.; Pokkuluri, P. R.; Farnum, B. H. Zinc-Catalyzed Two-Electron Nickel(IV/II) Redox Couple for Multi-Electron Storage in Redox Flow Batteries. Inorg. Chem. 2022, 61 (48), 19039–19048. https://doi.org/10.1021/acs.inorgchem.2c03124.

High Performance Anion Exchange Membranes with Confined Sub‐2‐nm Ion Channel

AbstractAs a key component of low‐cost anion exchange membrane fuel cells (AEMFCs), anion exchange membranes (AEMs) are far from commercial application, because of dissatisfactory alkaline stability and conductivity. Herein, a new insight is proposed to prepare high performance AEMs by constructing of confined ion channel. With an intermediate oligomer produced before the main copolymerization, novel poly(vinyl‐carbazolyl aryl piperidinium) AEMs with confined sub‐2‐nm ion channel are successfully prepared. The unique sub‐2‐nm ion channel enable membranes ultrahigh hydroxide conductivity of 261.6 mS cm−1, and the state‐of‐the‐art chemical stability over 5000 h. Moreover, the AEMs also exhibit good mechanical stability with lower water uptake and dimensional swelling. Based on the as‐prepared AEMs and ionomer, fuel cells exhibit outstanding peak power density of 1.8 and 0.2 W cm−2 with Pt‐based catalysts and completely non‐precious metal catalysts, respectively.