Stabilizing α-MnO2 Tunnel Structure via Mo–Zn Synergistic Doping for Highly Efficient Zn2+ Storage
Graphical A hydrothermal process is used for co-doping Mo and Zn into tunnel-structured MnO 2 (MZMO), enhancing its ion diffusion kinetics and electrical conductivity by introducing impurity energy levels and generating oxygen vacancies. This co-doping strategy also stabilizes the MnO 2 framework, enabling the MZMO cathode to achieve exceptional capacity, highly reversible H + /Zn 2+ co-intercalation, and prolonged cycle life. To address the rising demand for eco-friendly and efficient energy storage devices, rechargeable aqueous zinc ion batteries (AZIBs) are emerging as a promising candidate for large-scale energy storage. α-MnO 2 has attracted extensive attention for its open channels and exceptional Zn 2+ storage capacity. However, the electrochemical performance of α-MnO 2 is significantly hindered by severe structural collapse and sluggish reaction kinetics. Herein, we propose a simple hydrothermal approach for co-doping Mo and Zn into tunnel-structured MnO 2 (MZMO). The ion diffusion kinetics of MZMO are optimized due to ameliorated electrical conductivity by doped cations and introduced oxygen vacancies within the MnO 2 lattice. Moreover, Mo and Zn co-doping stabilizes the MnO 2 framework, significantly enhancing its electrochemical performance during prolonged cycling. Charge storage mechanism analysis further validates the extraordinary stability of the MZMO phase structure during the Zn 2+ /H + co-intercalation and deintercalation. The MZMO cathode demonstrates rapid and reversible Zn 2+ storage, with a high capacity of 395 mAh g −1 at 0.2 A g −1 , and the capacity remains at 136 mAh g −1 after 1000 cycles at 2 A g −1 . This study demonstrates Mo and Zn co-doping is an effective strategy to enhance the electrochemical performance of MnO 2 , offering valuable insights for developing other promising cathodes for AZIBs.
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