Water-proof, electrolyte-nonvolatile, and flexible Li-Air batteries via O-2-Permeable silica-aerogel-reinforced polydimethylsiloxane external membranes

Although aprotic Li-air batteries offer an attractive option for achieving ultrahigh energy density of electro-chemical energy storage devices, the now-established system has so far fallen short of its potential due to a daunting challenge related to its open configuration, which results in not only the rapid corrosion of Li metal anodes but also the gradual evaporation of organic liquid electrolytes. Here, we show that these issues can be well addressed by protecting the Li-air battery with a new O-2-permeable silica-aerogel-reinforced polydimethylsiloxane external membrane (OPSP). The highly flexible OPSP basically benefiting from hydrogen-bond cross-linking can be constructed in situ on any substrate with particularly desirable properties such as being water-/electrolyte-proof, O-2-permeable, high thermotolerance, and transparent, which allows stable cycling of coin-type and flexible Li-air batteries under harsh conditions, such as a highly volatile DMSO electrolyte (over 660 h), a humid air (O-2) atmosphere (over 700 h) or circumstances in air (O-2)-saturated liquid water (over 25 h). This work could potentially open a new research direction in developing O-2-permeable membranes through hydrogen-bond cross-linking for the unfettered design of metal-air batteries.