Techno-economically feasible beverage can as superior anode in rechargeable Al-air batteries

Abstract

Porous Fe nitrogen-doped carbon (Fe-NC) with a polyhedron structure, derived from zeolitic imidazolate framework 8 (ZIF8), was synthesized as an efficient electrocatalyst in Al-air batteries, complemented by a low-cost aluminium anode based on beverage cans. The highly-loaded porous Fe-NC demonstrated efficient catalytic activity towards the oxygen reduction reaction (ORR). This was linked to the good conductivity and the large surface area originating from the observed 3D porous architecture. The RDE test confirmed that the favourable 4-electron pathway for porous Fe-NC was higher than that of the 20 wt% Pt/carbon. Besides the high ORR activity, the Al-air battery demonstrated a maximum power density of 46 mW/cm2 at a current density of 80 mA/cm2. The galvanostatic discharge studies showed a stable voltage discharge plateau (>1.1 V) for current densities between 5 and 20 mA/cm2. The Al-air battery with porous Fe/NC catalyst exhibited a remarkably increased discharge capacity of 1920 mAh/g for the pure Al foil and 1173 mAh/g for the commercial Al can foil at a current density of 20 mA/cm2. The finding indicates that both anode and cathode in this work are techno-economically feasible materials. In addition, the Al-air battery showed large charge-discharge cycles (i.e., 180 cycles, 31 h) at 10 mA/cm2 with a low voltage gap using a beverage can.