Synergy of O2 Permeance and H2O Resistance by PIM-Enhanced PDMS Composite Membranes for “Closed-Type” Aprotic Li-Air Batteries

Aprotic Li-O₂ batteries exhibit ultra-high energy density through the redox reaction of O₂. However, their open-structure design makes them prone to water infiltration and electrolyte leakage. Traditionally, dense and thick oxygen-permeable membranes (OPMs) are employed to prevent H₂O intrusion, but this approach limits O₂ permeance and constrains charge current densities. To address the trade-off between O₂ permeance and H₂O resistance, a novel double-laminated film (DLF) is proposed as an OPM. This innovative design integrates a thin polydimethylsiloxane (PDMS) layer, known for its excellent H₂O resistance, onto a polymer of intrinsic microporosity (PIM-1) substrate, which offers high O₂ permeability. The resulting thin composite OPM (<40 µm) enables Li-air batteries to operate continuously for 90 cycles (180 h) in ambient air with a relative humidity of 50 ± 5% at 1000 mA g⁻¹, owing to the synergistic effects of the OPM's exceptional O₂ permeance (6881 Barrer, 215 GPU) and its effective mitigation of H₂O intrusion. The selective transport of O₂ and H₂O is facilitated by the hydrophobic apertures of the PDMS and PIM-1 layers, which exploit their kinetic differences. This work highlights the potential of high-free-volume, microporous polymers, and DLF architectures for advancing OPMs in aprotic Li-air battery applications.