Investigation of rechargeable zinc-air battery performance using a bifunctional biomass-derived catalyst material for the air electrode

Active transition metal-containing nitrogen-doped bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were prepared using a biomass precursor of rapeseed press cake, an inexpensive byproduct of rapeseed oil production. The prepared catalysts were thoroughly characterized and the most active material 4Fe4NiNCR was used as an air electrode catalyst in rechargeable Zn-air batteries (ZABs). A high peak power density ( P max ) of 202 mW cm −2 was observed, which was comparable to commercial 50:25:25 PtRu/C catalyst performance ( P max = 205 mW cm −2 ). The rechargeable Zn-air battery was stable for 68 h (68 cycles) at a practically relevant areal cycling capacity of 12.5 mAh cm −2 and a current density of 25 mA cm −2 . This was a significantly improved performance compared to only 5 h (5 cycles) using the 50:25:25 PtRu/C catalyst. The best catalyst 4Fe4NiNCR was shown to be promising for practical usage in rechargeable ZABs. Additionally, various ZAB design parameters are considered and discussed in detail on the basis of measurements done with two different battery configurations.