Clustered multi-imidazolium side chains functionalized alkaline anion exchange membranes for fuel cells

Guo, Dong; Lin, Chen; Hu, En Ning; Shi, Lin; Liu, Changkun; Zhang, Qiu Gen; Zhu, Ai Mei

doi:10.1016/j.memsci.2017.07.007

Cited by 66 publications

(19 citation statements)

References 45 publications

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“…Apart from the backbone structure, the other decisive factor in the long-term AEM construction is the stability of the cationic group. A variety of functional groups have been used for hydroxide ion conduction, such as quaternary ammonium, imidazolium, guanidinium, pyrrolidinium, phosphonium groups, etc. It is recognized that the quaternary ammonium groups are unstable in high pH solutions; their degradation mechanism mainly involves the Hofmann elimination, direct nucleophilic substitution, etc .…”

Section: Introductionmentioning

confidence: 99%

Branched, Side-Chain Grafted Polyarylpiperidine Anion Exchange Membranes for Fuel Cell Application

Bai

et al. 2021

ACS Appl. Energy Mater.

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Anion exchange membrane (AEM) is the heart of alkali electrolyte membrane fuel cells (AEMFCs). To achieve high performance of AEMFC, high conductivity and alkaline stability of AEMs are highly desired. In the present work, we report the synthesis of ether-free polymers with different degrees of Y-shaped branching as AEM materials. Our investigations reveal that incorporating bulky, rigid, and Y-branching units into the polymer backbone can increase the free volume of the AEM and thus help build ion channels with lower hydroxide ion transport resistance. The resultant AEM showed a markedly improved ionic conductivity (116.92 mS/cm at 80 °C), while the simple linear type of the AEM only showed an ion conductivity of 63.63 mS/cm at a similar ion exchange capacity. With such an AEM, the peak power density of the H2/O2 single cell at 60 °C reaches 275 mW/cm2.

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Section: Introductionmentioning

confidence: 99%

Branched, Side-Chain Grafted Polyarylpiperidine Anion Exchange Membranes for Fuel Cell Application

Bai

et al. 2021

ACS Appl. Energy Mater.

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“…As a general note, the functional cation is deemed as the most susceptible group by the attack of the highly nucleophilic hydroxide ion; therefore, apart from traditional quaternary ammonium (QA), lots of alternative cationic species, such as phosphonium, − imidazolium, − guanidinium, − and a ligand–metal complex cation, , have been evaluated for the possibility of AEMFC use. Unfortunately, apart from sterically protected imidazolium, − most of these investigated alternatives were not suitable for the sake of complicated synthetic processes, induced high-water absorption, or endurable instability.…”

Section: Introductionmentioning

confidence: 99%

High Ion Conductivity and Diffusivity in the Anion Exchange Membrane Enabled by Tethering with Multication Strings on the Poly(biphenyl alkylene) Backbone

Zhang

Jiang

et al. 2020

ACS Appl. Energy Mater.

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Aryl ether-free polyaromatics tethered with quaternary ammoniums (QAs) offer a promising candidate as an anion exchange membrane (AEM) for use in alkaline fuel cells. However, the traditional trade-off dilemma between the ion conductivity and water swelling of the AEM still remains. Herein, we report a series of poly(biphenyl alkylene) (PBPA) polymers tethered with multiple QAs per side chain that combine the advantages of a high ion conductivity, high ion diffusion coefficient, and suppressed water uptake. Upon increasing the number of QAs on each side chain, the degree of phase separation of the resulting AEM increased, thereby improving the ion diffusion coefficient from 2.03 × 10–6 cm2 s–1 for a single-QA-based PBPA100-1QA to 2.26 × 10–6 cm2 s–1 for a triple-QA-based PBPA35-3QA. The side chain triply-charged membranes show much improved performances. Specifically, at a given ion exchange capacity (IEC) of 2.5 mmol g–1, despite a notably low water uptake that was observed, the PBPA35-3QA exhibited a conductivity ∼40% higher than that of PBPA100-1QA. The highest conductivity was observed for PBPA50-3QA (IEC = 3.1 mmol g–1), achieving a 63 mS cm–1 chloride conductivity at 80 °C, while the corresponding water uptake was well-suppressed within 116 wt %. Owing to the high conductivity and ion diffusivity as well as the suppressed water uptake, a fuel cell fabricated with the 25 μm thick PBPA35-3QA membrane showed a low high-frequency resistance of 0.03 Ω cm2. However, the triple-QA-based membrane showed an 18% cation degradation after aging for 300 h in 2 M NaOH at 80 °C, which is a significantly inferior value than those of the counterparts with a low number of QAs on the side chains.

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“…These values are comparable to that of polymerized ionic liquid block copolymer membranes (30 mW cm −2 at 60 °C), imidazolium‐type ionic liquid based membranes (30 mW cm −2 at room temperature), and PVA/PDDA alkaline anion‐exchange membranes (35.1 mW cm −2 at room temperature) and even higher than those of quaternized chitosan membranes (23 mW cm −2 at 50 °C), CS/EMImC‐Co‐EP‐OH − membranes (21.7 mW cm −2 at room temperature), and PVA/TiO 2 composite membrane (7.54 mW cm −2 at 60 °C) . However, the cell performance of the CTS/[QAIM]OH/MWCNTs‐OH membrane is much lower than that of Nafion membranes and some other AEMs such as NVMP/NVEP membranes, QPVA/Fe 3 O 4 @GO membranes, and multi‐cation TrimPES membranes . This may be explained by the following two facts: (1) the OH − conductivity of the membrane is not high, and (2) the MEA fabrication conditions are not optimized.…”

Section: Resultsmentioning

confidence: 99%

Studies on a novel anion‐exchange membrane based on chitosan and ionized organic compounds with multiwalled carbon nanotubes for alkaline fuel cells

Zhou

2018

J of Applied Polymer Sci

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In this work, a novel hydroxyl-anion-conducting membrane composed of chitosan (CTS), an ionized organic compound ([QAIM]OH), and hydroxylated multiwalled carbon nanotubes (MWCNTs-OH) has been fabricated through a blending-casting method assisted by a glutaraldehyde (GA) crosslinking process that can improve the mechanical properties of the membrane effectively. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy revealed that [QAIM]OH and MWCNTs-OH were successfully introduced into the CTS matrix. A chemical crosslinking reaction between CTS and GA could be confirmed by FTIR, X-ray photoelectron spectroscopy, and contact angle tests. By tuning the mass fraction of [QAIM]OH and MWCNTs-OH in the membrane, the maximum OH 2 conductivity (5.66 3 10 23 S cm 21 at room temperature) could be achieved for the composition CTS:[QAIM]OH (1:0.75 in mass) blend doped with 3% MWCNTs-OH. At a current density of 59.9 mA cm 22 , a membrane electrode assembly fabricated with the CTS/[QAIM]OH/ MWCNTs-OH membrane (1:0.5/3%) achieved a power density of 31.6 mW cm 22 in a H 2 /O 2 system at room temperature. Under the condition of intermediate temperature (100-140 8C) without water, the conductivities of the membranes increased with increasing temperature and the amount of [QAIM]OH, which acted as an ionic liquid in the membrane, indicating that the ionic transport behaviors could still be occurring.

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Clustered multi-imidazolium side chains functionalized alkaline anion exchange membranes for fuel cells

Cited by 66 publications

References 45 publications

Branched, Side-Chain Grafted Polyarylpiperidine Anion Exchange Membranes for Fuel Cell Application

Branched, Side-Chain Grafted Polyarylpiperidine Anion Exchange Membranes for Fuel Cell Application

High Ion Conductivity and Diffusivity in the Anion Exchange Membrane Enabled by Tethering with Multication Strings on the Poly(biphenyl alkylene) Backbone

Studies on a novel anion‐exchange membrane based on chitosan and ionized organic compounds with multiwalled carbon nanotubes for alkaline fuel cells

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