"Bubble-Diode" Breathable Electrodes for Fast Gas Transport.

ABSTRACT

Bubbles arising from wild gas evolution commonly exist in electrochemical systems, particularly in water electrolysis and rechargeable aqueous batteries (e. g., Zn-air batteries). Substantial energy dissipation occurs due to the obstruction of active sites and ion-conducting pathways by evolving bubbles. Efforts are made to elucidate effective strategies for fast gas transport, most of which focus on minimizing bubble size and facilitating their timely detachment through complex techniques such as constructing super-hydrophilic nano-structure electrodes, flowing electrolytes, and ultrasonic oscillation. Recently, an innovative, facile, and highly efficient method utilizing a breathable electrode design to promote gaseous molecules to the external environment emerges as a promising approach since it avoids remarkable bubble accumulation while remaining free of additional accessories. This paper highlights the origin and evolution of this promising design. Starting with introducing the basic concept of traditional breathable electrodes based on hydrophobic polymer networks and discussing the current progress made in underlying mechanisms, a detailed description of the advanced design inspired by a "bubble-diode" concept with superior breathability follows. This Concept aims to contribute to a deep understanding of this technology and paves the way for further advancements in this renewable energy era.