Tailoring Three-Dimensional Composite Architecture for Advanced Zinc-Ion Batteries

Rechargeable aqueous Zn-ion batteries (ZIBs) are of considerable interest for future energy storage. Their main limitation, however, is developing suitable cathode materials capable of sustaining the Zn2+ repeated intercalation/deintercalation. Herein, a threedimensional polypyrrole (PPy)-encapsulated Mn2O3 composite architecture is developed for advanced ZIBs. The engineering can be easily realized via in situ phase transformation of MnCO3 microboxes with subsequent self-initiated polymerization of PPy. The abundant open-up pores (similar to 30 nm) throughout the construction accelerate ion migration and provide a more active interface for Zn2+ storage in the Mn2O3@PPy bulk electrode. Meanwhile, the PPy skin uniformly wrapped on the Mn2O3 microbox not only guarantees a good conductive network for faster electron transport but also inhibits the dissolution of Mn2O3 and protects the integrity of the electrode from structural damage. As a result, the Mn2O3@PPy electrode can operate at reversible capacity exceeding those of most other cathode materials, but can still provide longer lifetime (no capacity decay over 2000 cycles at 0.4 A g(-1)) and higher rate performance than others. Furthermore, theoretical studies show the H+ and Zn2+ coinsertion storage mechanism and reaction dynamics. The results show that this three-dimensional Mn2O3@PPy architecture is a promising cathode material for highperformance ZIBs.