Highly OH<sup>–</sup> Conductive Membranes Enabled by 2D-Hydrogen Bonding Networks within Layered Confined Nanofluidic Channels
J.B Li, Xiaomin Tang, Liping Zhi, Lixin Liang, Li Dongguo, Zhiqiang Liu, Anmin Zheng, Zhizhang Yuan, Xianfeng Li
Abstract
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.