Anion exchange membranes (AEMs) are one of the core components of AEM fuel cells. A series of poly(vinyl alcohol)/polyquaternium‐10 (PVA/PQ‐10) AEMs with semi‐interpenetrating networks (s‐IPNs) are prepared by a simple solution‐casting method using glutaraldehyde (GA) as a cross‐linking agent. Subsequently, the prepared PVA/PQ‐10 cross‐linked membranes are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, mechanical analysis, water uptake and swelling ratio tests, ion exchange capacity (IEC) tests, ionic conductivity measurements, and oxidative/alkaline stability tests. The effects of the mass ratio of PVA and PQ‐10 and the amount of cross‐linking agent GA on the performance of the PVA/PQ‐10 cross‐linked membranes are systematically explored. The results show that the cross‐linked PVA/PQ‐10 AEMs have high IEC and low water uptake and swelling ratio, and its maximum ionic conductivity can reach 79.37 mS cm–1 at 80 °C. In addition, the PVA/PQ‐10 cross‐linked membrane has good oxidative and alkaline stability under optimal preparation conditions. These results may provide valuable insights toward more effective scheme designs and new, simple preparation methods for AEMs with s‐IPN structures.

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Anion exchange membranes with chemical stability, high conductivity, and high mechanical properties play an important role in alkaline fuel cells. Here, a series of CPX anion exchange membranes based on poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) and branch polyethyleneimine (BPEI) are achieved by casting, in which BPEI acts as both a crosslinking agent and an OH− conducting functional group. The introduction of BPEI facilitates the formation of good hydrophilic/hydrophobic microphase separation structure, thus improving the ion transport channel of CPX membrane. The physicochemical and electrochemical properties of the CPX membrane are significantly improved when the mass ratio of SEBS to BPEI is within an appropriate range. The OH− conductivity of the CP2 membrane (the mass ratio of SEBS to BPEI is 2) can reach 66.63 mS cm−1 at 80 °C, and more than 80% initial OH− conductivity is maintained in 1.0 m NaOH solution for 20 d at 60 °C. The strategy of using a polymer with excellent alkali resistance and oxidation resistance as the main body and introducing a conductive group that can construct microphase separation can simultaneously improve the conductivity and membrane stability. This viable strategy is a promising construction method for anion exchange membranes that can be applied to fuel cells.

Anion exchange membrane (AEM) is essential for the development of alkaline anion exchange membrane fuel cells, and its performance largely depends on its internal microstructure. Herein, to improve the performance of AEM, quaternized branched polyethyleneimine modified nitrogen‐doped graphene quantum dots (QBPEI@N‐GQDs) are introduced to quaternized polysulfone (QPSU) polymer matrix to prepare a series of QPSU/QBPEI@N‐GQDs (QQ‐n‐N‐GQDs) composite AEMs. Due to the uniform distribution of hydrophilic QBPEI@N‐GQDs, an obvious hydrophilic/hydrophobic microphase separation structure is formed inside the QQ‐n‐N‐GQDs composite AEMs. Compared with the pristine QPSU AEM, the QQ‐0.7%‐N‐GQDs AEM shows slightly higher water uptake (WU) and swelling ratio (SR), as well as much higher ionic conductivity (76.18 mS cm−1 at 80 °C for QQ‐0.7%‐N‐GQDs AEM versus 46.14 mS cm−1 at 80 °C for pristine QPSU AEM) and better maximum power density of single fuel cell (85.2 mW cm−2 for QQ‐0.7%‐N‐GQDs AEM versus 46.3 mW cm−2 for QPSU AEM). Moreover, the chemical stability of QQ‐n‐N‐GQDs composite AEMs has not been significantly adversely affected by the introduction of QBPEI@N‐GQDs.

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Anion exchange membrane fuel cells (AEMFCs), which operate on a variety of green fuels, can achieve high power without emitting greenhouse gases. However, the lack of high ionic conductivity and long-term durability of anion-exchange membranes (AEMs) as their key components is a major obstacle hindering the commercial application of AEMFCs. Here, a series of homogeneous semi-interpenetrating network (semi-IPN) AEMs formed by cross-linking a copolymer of styrene (St) and 4-vinylbenzyl chloride (VBC) with branched polyethylenimine (BPEI) were designed. The pure carbon copolymer skeleton without sulfone/ether bonds accompanied by the semi-IPN endows the AEMs with excellent chemical stability. Moreover, the cross-linking effect of flexible BPEI chains is supposed to promote the “strong-flexible” mechanical properties, while the presence of multiquaternary ammonium groups can boost the formation of microphase separation, thereby enhancing the ionic conductivity of these AEMs. Consequently, the optimized (S1V1)3Q AEM exhibits an excellent hydroxide conductivity of 106 mS cm–1 at 80 °C, as well as more than 81% residual conductivity after soaking in 1 M NaOH at 60 °C for 720 h. Furthermore, the H2/O2 fuel cell assembled with (S1V1)3Q AEM delivers a peak power density of 150.2 mW cm–2 at 60 °C and 40% relative humidity. All results indicate that the approach of combining a pure carbon backbone polymer with a semi-IPN structure may be a viable strategy for fabricating AEMs that can be used in AEMFCs for long-term applications.