Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability, high efficiency, and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries. Here, 3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated (referred to as PEMAC@NDCN) by a facile self-templated approach. PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability, which outperforms those of commercial Pt/C and RuO2. Theoretical calculations and control experiments reveal the boosted electron transfer, electrolyte mass/ion transports, and abundant active surface site preferences. Moreover, the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density, capacity, and discharge-charge cycling stability (over 2160 cycles) compared to the reference Pt/C + RuO2. Solid-state Zn-air batteries enable a high power density of 211 mW cm-2, energy density of 1056 Wh kg-1, stable charge-discharge cycling of 2580 cycles for 50 mA cm-2, and wide temperature tolerance from - 40 to 70 °C with retention of 86% capacity compared to room-temperature counterparts, illustrating prospects over harsh operations.
Keywords: Alkaline and flexible solid-state Zn–air batteries; All-temperature operations; Flexible free-standing membrane electrocatalysts; High capacity and energy density; Supramolecular polymer.
© 2022. The Author(s).