Negative surface charge-mediated Fe Quantum dots with N-doped graphene/Ti3C2Tx MXene as chlorine-resistance electrocatalysts for high performance seawater-based Al-air batteries

Abstract

Compared to conventional alkaline Aluminum-air (Al - air) batteries, seawater-based Al-air batteries are promising large-scale energy storage devices and are highly compatible with offshore ocean locations or large-scale maritime applications. However, the complexity of the seawater components, in particular, chlorine anions (Cl−) blocks the metal surface and hinders the oxygen reduction reaction (ORR) at the cathode. Herein, we employed plasma engineering to anchor Fe Quantum dots (QDs) on a negative charge-mediated surface composed of nitrogen-doped graphene (NG) and Ti3C2Tx MXene. The negative fluorine and hydroxyl groups on MXene and NG induced strong negative-charged surface with a build-in electric field to repel Cl−, effectively protected the Fe QDs active sites from the seawater electrolyte. As a result, the cathode electrocatalysts demonstrated high ORR catalytic activity in seawater electrolytes and achieved a high-power density output of 53.6 mW/cm2 and rate performance of 0.8 V at 50 mA/cm2 in Al-air seawater batteries.