One‐Dimensional MnO2 Nanowires Space‐Confined in Hollow Mesoporous Carbon Nanotubes for Enhanced Zn2+ Storage Performance

The yolk‐shell structure exhibits fascinating and important properties for energy storage devices. The carbon shell significantly improves the good electrical conductivity and the stable micro‐/nanostructures of the active material increases utilization. MnO2@C with a yolk‐shell structure shows high reversibility, good rate performance, and excellent cycling stability for aqueous Zn‐ion batteries. The Zn‐ion battery with MnO2@C could realize a high reversible capacity of 239 mAh g−1 at 0.1 A g−1. In particular, at a quite high current density of 2 A g−1, it achieves capacity of 91 mAh g−1. The Zn‐ion battery has excellent capacity retention of up to 1000 cycles at 1 A g−1. The yolk‐shell structure plays an important role in improving the battery performance. Confined space: A yolk‐shell structured MnO2@carbon composite is prepared, which is made up of one‐dimensional MnO2 nanowires space‐confined in hollow mesoporous carbon nanotubes. Compared to pure MnO2, yolk‐shell structured MnO2@C has a higher capacity, better rate capability, and excellent cycling stability as a cathode material for Zn‐ion batteries.