Sulfonated porous aromatic frameworks (SPAFs) accelerate Li-ion diffusion while retarding the polysulfide shuttle effect in Li–S batteries. This leads to high residual capacity above 1000 mA h g−1 and coulombic efficiency (>99.5%) after 500 cycles.

Vanadium crossover hinders widespread commercial adoption of vanadium redox flow batteries (VRFBs). Superglassy polymers have the potential to offer high selectivity needed to control the crossover but as yet do not possess the requisite proton conductivity and stability. Here, we explore nanocomposite separators that can improve this selectivity. We report a dual-function charge carrier molecular sieve (CCMS) membrane, consisting of a high free volume microporous glassy polymer, poly[1-(trimethylsilyl)-1-propyne] (PTMSP)/sulfonated PAF (PAF-1-SO 3 H), that effectively hinders the migration of hydrated vanadium ions. Furthermore, ideally placed PAF-1-SO 3 H pores not only proved excellent for developing proton conductive channels but also suppressed physical aging within the separator. Experiments then linked this to an increased battery cycle life. As a consequence of achieving higher and more stable VRFB performance compared to benchmarked Nafion (Coulombic efficiencies of 97 vs 87% and capacity retention values of 85 vs 58% at a current density of 60 mA cm −2 , respectively), our integrated design heralds a class of stable separators for hydrogen-based energy technologies. KEYWORDS: super glassy polymer, sulfonated porous aromatic framework, thin-film composite mixed matrix membrane, charge carrier molecular sieve (CCMS) separator, H + /V 4+ selectivity, vanadium redox flow battery

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