Highly OH^- Conductive Membranes Enabled by 2D-Hydrogen Bonding Networks within Layered Confined Nanofluidic Channels

Membranes that combine high OH^- conductivity (>10^-2 S cm^-1) with long-term stability remain urgently needed for energy-related devices. Herein, we present a general confined structure-controlled strategy to fabricate highly stable layered double hydroxide (LDH)-based membranes with high conductivity (450 mS cm^-1 in 30 wt % KOH solution at 25 °C) enabled by tuning OH^- transport through 2D- and 3D-hydrogen-bonding networks in layered confined nanofluidic channels. By controlling the interlayer spacing of LDH, distinct hydrogen bonding networks can be achieved, and the directional OH^- transport in the layered confined channels can be accelerated efficiently in a 2D-hydrogen-bonding network. The designed membranes exhibit <1% mass degradation after more than 10,000 h in a 30 wt % KOH solution at 80 °C and work efficiently for use in alkaline water electrolyzers (∼1.7 V for over 4,000 h at 300 mA cm^-2), anion exchange membrane water electrolyzers (∼1.65 V for over 2,000 h at 250 mA cm^-2), and alkaline zinc-iron flow batteries (∼500 cycles at 260 mA cm^-2 with energy efficiency >78%). This work shows that a membrane with both high OH^- conductivity and stability is possible, offering a new and evolutionary option for alkaline-based energy-related devices.