Dual engineering of electronic structure and interface: A synergistic Co-doped δ-MnO2/MXene cathode for Zn-ion batteries with ultrahigh capacity and cycling stability

The practical application of manganese dioxide (MnO 2 ) in Zn-ion batteries (ZIBs) is hindered by intrinsic limitations such as low electronic conductivity, slow ion diffusion, and structural instability. To address these challenges, we report a Co-doped δ-MnO 2 /MXene composite (CMM) cathode, fabricated via a facile one-step room-temperature synthesis. This design creates a synergistic coupling effect, where MXene provides a conductive scaffold while cobalt doping modulates the electronic structure of MnO 2 . This dual modification collectively enhances electrical conductivity, expands the active surface area, and significantly accelerates ion diffusion kinetics. As a ZIB cathode, the CMM electrode demonstrates exceptional charge storage performance: delivering a high specific capacity of 480.9 mAh g −1  at 0.1 A g −1 , and exhibiting exceptional long-term durability with over 100 % capacity retention after 2000 cycles at 1 A g −1 . Remarkably, it achieves an outstanding energy density of 651.6 Wh kg −1  at a power density of 135.5 W kg −1 , significantly outperforming both δ-MnO 2 /MXene (MM) and pristine δ-MnO 2 cathodes. This work establishes an effective synergistic regulation strategy and provides profound insights into the design of high-performance cathode materials for advanced energy storage systems.