Rechargeable Zn-Air Batteries with Pulse-Power Capability
Technical Report,01 Oct 2016,30 Sep 2019
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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Zincair batteries are energy-storage devices that are safe to operate thanks to nonflammable aqueous electrolytes, use an abundant, domestically sourced active material Zn, and provide high specific energy by harvesting O2 from air to serve as the oxidant. Despite these attractive features, the implementation of Znair batteries for military and civilian applications is constrained by the limited rechargeability and power response of present Znair technology. The Advanced Electrochemical Materials Section at the U.S. Naval Research Laboratory executed a 6.2 research program from FY16FY19 in which the focus was to address remaining roadblocks to high-performance, rechargeable Znair batteries through targeted development efforts and leveraging related developments at the NRL with advanced 3D porous Zn electrodes. The core of this program was the development of a trifunctional air cathodethe first of its kindthat expresses the three critical functions of O2-evolution reaction OER, O2-reduction reaction ORR, and pulse-power. The trifunctional cathode comprises a powder composite layer functionalized with pre-formed OER and ORR catalysts that are bonded to a MnOx-modified carbon nanofoam paper that provides pulse-power. En route to the final cathode structure, bifunctional ORR OER catalysts were designed, fabricated, and their electrochemical performance and stability were optimized. Down-selected bifunctional air cathodes were paired with the NRL-patented Zn sponge anode in prototype coin cells to demonstrate Znair cell performance and rechargeability. The combination of the bifunctional composite cathode with pulse-power enabling MnOx-modifed carbon nanofoams was then demonstrated. The advances derived from this 6.2 program readily transition to civilian and military uses, and serve as an enabling technology for the portable-power requirements of the next generation warfighter.
- Electrochemical Energy Storage