Rational Design of Porous Y2O3-MnOx/Carbon Heterostructures with Abundant Oxygen Vacancies for High-Efficiency and Ultrastable Zinc-Ion Storage.

Abstract

Manganese oxides have been considered as the most competitive cathode materials for aqueous zinc-ion batteries (ZIBs) on account of their inherent safety, high operating voltage, environmental friendliness, and cost-effectiveness. Unfortunately, the manganese dissolution, inherently poor electronic conductivity, and the sluggish reaction kinetics of commercial manganese-based oxides severely hinder their practical applications. To address the above issues, we creatively developed hierarchical porous Y₂O₃-MnO_x/C nanorods (named O_V-YMO/C) with unique heterostructures and abundant oxygen vacancies via a facile MOF-assisted synthetic process and employed as the advanced cathode. Owing to the well-constructed porous structure, larger surface areas, abundant oxygen vacancies, and strong synergetic coupling effect at the heterogeneous interface, the as-obtained O_V-YMO/C cathode exhibited a fascinating discharge capacity of 389.6 mAh g^-1 at 0.1 A g^-1. Simultaneously, it demonstrated remarkable rate performance (233 mAh g^-1 at 4.0 A g^-1) and cycling durability (90.6% capacity retention over 3000 cycles at 4.0 A g^-1). The fabricated Zn//O_V-YMO/C pouch cell could deliver superior flexibility and electrochemical stability under extreme bending conditions. Furthermore, the electrochemical reaction mechanism was comprehensively explored by kinetic analysis and density functional theory (DFT) calculations. The synergistic strategy by subtly combining the MOF-assisted approach, heterojunction engineering, and oxygen defects engineering provides valuable insights into the construction of cathode materials for high-rate and ultrastable aqueous ZIBs.