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 three-dimensional 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 (∼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 high-performance ZIBs.