Phase-Transfer Catalyst for Lithium-Oxygen Batteries Based on Bidirectional Coordination Catalysis: 2-Aminopyridine

Abstract

Li-O₂ batteries are considered promising candidates for next generation high energy storage systems due to their exceptionally theoretical energy density. However, the accumulation of insulating discharge product Li₂O₂ leads to severe cathode passivation, reduced conductivity, and hindered charge transfer, which seriously compromise the battery performance. This work proposes a novel phase-transfer catalyst with bidirectional coordination functionality, 2-aminopyridine (AP). The AP molecule contains a nucleophilic pyridine nitrogen and an electrophilic amino hydrogen, which can interact with Li⁺ and reactive oxygen intermediates through electrostatic attraction and hydrogen bonding, respectively. This dual interaction facilitates the liquid-phase deposition of Li₂O₂ while enabling efficient product decomposition. The uneven electrostatic potential distribution within the AP molecule generates an internal electric field that stabilizes reduced oxygen species, shields against nucleophilic attacks, and suppresses Li⁺ deposition at the anode tips, effectively preventing lithium dendrite growth. Therefore, Li-O₂ batteries with AP exhibit an exceptionally high discharge capacity of 36419 mAh g⁻¹, a significantly reduced charge over-potential of 0.29 V, and an extended cycle life exceeding 2256 h. Through functional molecular structure design, the bidirectional coordination catalytic effect demonstrated by AP molecules effectively regulates the migration and interaction of substances during reactions, significantly improves the electrochemical performance of Li-O₂ batteries.