Humidity and Pressure Dual-Responsive Metal-Water Batteries Enabled by Three-in-One All-Polymer Cathodes for Smart Self-Powered Systems.

A conceptually new class of humidity and pressure dual-responsive smart metal-water battery (SMWB) is presented, which displays self-tunable energy release and intriguing perceptibility of human respiration and environmental pressure. This battery is enabled by the direct contact of a metal (e.g. Mg, Zn) anode and a well-designed all-polymer dual-sensitive moisture electrode (DSME) made from semi-conductive polymer (e.g. polypyrrole) wrapped 3D macroporous polyurethane sponge, without addi-tional electrolytes and separator. DSME is cost-effective, easily scalable, compressible and able to act as a moisture carrier, a hydrogen evolution catalyst and a pressure and humidity dual-sensitive unit simultaneously. Unique three-in-one integration in DSME enables favorable modulation of electron/mass transport or redox reactions in SMWB upon different stimulations. Thus, the assembled SMWB not only delivers good discharge performance with smart energy management, but also serves as a relia-ble self-powered bifunctional responsor for the real-time monitoring of respiration and the perceptibility of pressure. Based on various active metal-polymer pairs (Mg/Zn vs. polypyrrole/polyaniline), we also developed a series of dual-responsive batteries, demonstrating a general design idea.