Synergistic Coupling of Mn3O4-N-C Cathode and Additive-Mediated Anode Stabilization for High-Utilization Alkaline Al-Air Batteries

Abstract

Alkaline aluminum-air batteries (AABs) hold immense potential for next-generation energy storage due to their ultrahigh theoretical energy density and cost-effectiveness. However, their commercial viability is severely restricted by the “dual bottlenecks” of rampant anodic parasitic reactions (self-corrosion and hydrogen evolution) and sluggish cathodic oxygen reduction reaction (ORR) kinetics. Herein, we orchestrate a synergistic dual-electrode engineering strategy to simultaneously address these issues. On the cathode side, a Mn3O4-N-doped carbon composite electrocatalyst (Mn3O4-N-C) is prepared via gel-assisted pyrolysis, exhibiting competitive ORR activity with a half-wave potential of 0.893 V. On the anode side, tin(II) 2-ethylhexanoate (TEA) is introduced as a multifunctional electrolyte additive to reconstruct the Al anode interface. Mechanistic studies reveal that the 2-ethylhexanoate anions form a hydrophobic organic shield via adsorption, while Sn2+ undergo in situ reduction to form a high-hydrogen-overpotential Sn layer. This organic-inorganic hybrid protection mechanism effectively suppresses self-corrosion and guides uniform Al dissolution. Consequently, the assembled AABs achieve a high anode utilization of 78.6% and a specific capacity of 2382.5 mAh g–1 at 20 mA cm–2, approaching the theoretical limit. This work provides a holistic material design paradigm for constructing high-efficiency and robust AABs.