Dressing the manganese dioxide cathode with close-fitting thin carbon film to suppress the dissolution and expansion

Conductive layer modification, such as carbon coating layers, has also been widely reported to alleviate the continuous metal ion dissolution and volumetric expansion of rechargeable aqueous zinc-ion batteries (ZIBs) cathode. However, the thick coated layer acts as the inactive material cannot provide enough zinc ion storage sites, reducing the capacity of cathode materials. Here, to address this challenge, we have developed a dressed manganese dioxide nanorods (MnO2-NRs) cathode featuring a close-fitting confinement interface constructed from a hydrogen-substituted graphdiyne (HsGDY) thin film (MnO2-NRs@HsGDY). The unique hierarchical pore structure and active acetylene bonds of HsGDY film contribute to fast electron/ion transport channel, additional ion storage active site, and structural stability by enriching Zn2+ Sions and confining Mn2+ ions on MnO2-NRs surface. The MnO2-NRs@HsGDY-based ZIBs exhibit an ultra-high reversible specific capacity of 432 mAh/g under a current density of 50 mA g-1, as well as excellent cyclic stability and superior rate performance. Based on the MnO2-NRs@HsGDY, a folding and flexible battery with a high energy density of 162.5 Wh kg-1 at 1 A g-1 can be easily fabricated. Those results demonstrate a straightforward and controllable approach for preparing high-performance cathode materials applied for flexible ZIB.

Automated summary

By using a graphdiyne thin film to encapsulate manganese dioxide nanorods, high-performance cathode materials for rechargeable aqueous zinc-ion batteries have been achieved. The unique structure and active bonds of the material contribute to fast electron/ion transport and increased ion storage, leading to improved capacity and cycling stability.