All-solid-state sponge-like squeezable zinc-air battery

Squeezable energy storage devices, including those zinc air batteries (ZABs) of high theoretical energy densities, are of great interest for flexible and wearable electronics that are able to accommodate large strains without remarkable loss in electrochemical performance and reliability. However, the performance of ZABs in such flexible environment is significantly hindered by the kinetically sluggish rate of oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) in the air electrode, especially upon large deformation due to the lack of highly active and squeezable electrode materials. Herein, we present an advanced electrode by directly depositing Fe-doped Co3O4 nanowires on nitrogen-doped carbon foams (Fe-Co3O4 NWs@NCFs) with superior bifunctional catalytic performance (Ej=10 (OER) - E1/2 (ORR) = 0.61 V) in an alkaline medium. As a proof-of-concept application, a highly squeezable all-solid-state ZAB was assembled with Fe-Co3O4 NWs@NCFs as the air electrode and Zn NSs@NCFs (electrodeposited Zn nanosheets on NCFs) as the Zn electrode, which is shown to possess a high open circuit potential (1.51 V), a low discharge/charge voltage gap (0.657 V at 5 mA cm−2) and a large power density (260 mW cm−2). Furthermore, the great squeeze-ability (up to 60% strain) and mechanical endurance properties (tested by repetitive compressions for 500 cycles) in particular make the ZAB a potentially promising power source for compression-tolerant electronics.