Modulating oxygen reduction reaction activity in nitrogen-doped porous carbon via Al-N-C incorporation for enhanced performance in liquid and solid-state Zn-air batteries

Zinc-air batteries (ZABs) exhibit exceptional energy density and inherent safety yet necessitate cost-effective and stable catalysts to bolster the cathode oxygen reduction reaction (ORR). This work presents a nitrogen-doped porous carbon (NPC) structure with highly dispersed aluminum-based active sites that demonstrate remarkable performance in ORR catalysis. Advanced analytical tools, including time-of-flight secondary ion mass spectrometry (ToF-SIMS), confirm the presence of Al-N4-N motifs with axial N-ligands, significantly augmenting catalytic efficiency. In-situ surface-enhanced Raman spectroscopy (SERS) reveals the rate-limiting step to be the initial proton-coupled electron transfer process, evidenced by the delayed emergence of the ∗OOH band compared to the ∗O₂ band. High-resolution scanning electrochemical microscopy (SECM) is employed to decipher the local reactivity distribution across varying potentials and temperatures, elucidating the electrochemical characteristics. Incorporating this synthesized material as the cathode in a liquid-state ZAB yields a capacity of 750 mAh g⁻¹ and a power density of 144 mW cm⁻², alongside commendable cyclic stability. Furthermore, the constructed all-solid-state ZAB demonstrates outstanding cycling stability under diverse bending conditions, emphasizing its robustness and potential for flexible energy storage applications. This work represents a significant advancement in the field, paving the way for the development of more efficient, reliable, and cost-effective ZAB technologies.