Boosting the performance of alkaline Al-air batteries by interfacial reconstruction via N-doped carbon quantum dots

Abstract

Al-air batteries (AABs) have garnered attention as an innovative energy source with remarkable performance. Unfortunately, the self-corrosion of Al anodes in alkaline electrolytes impedes its commercialization. This study presents N-doped carbon quantum dots (N-CQDs), synthesized via the hydrothermal method, as electrolyte additives in a 4 M NaOH solution, owing to their quantum size, exceptional dispersion, and polar surface functional groups, which facilitate corrosion inhibition and interfacial stabilization. The influence of varying concentrations of N-CQDs on the self-corrosion of Al and the discharge characteristics of AABs was investigated. The reconstruction of Al-electrolyte interface was explored using electrochemical procedures, hydrogen evolution tests, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and molecular simulation methods. Our results indicated that at a concentration of 150 mg/L of the N-CQDs inhibitor, the inhibition efficiency reaches 68.4 %. Concurrently, the anode utilization improves from 41.4 % to 85.0 %, the capacity density escalates from 1234.6 to 2531.6 mAh g⁻¹, and the energy density increases from 1540.2 to 3367.0 Wh kg⁻¹. This concept of a dynamic monolayer protective interface presents an alluring avenue for stable Al anodes, as well as an effective strategy to advance the practical implementations of AABs.