High-Crystallinity MnO₂ with Enhanced Structural Integrity for Aqueous Zn²⁺ Storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Manganese dioxide (MnO2) is a potential cathode material for aqueous zinc ion batteries (AZIBs).
• Jahn-Teller distortion and dissolution limit MnO2 performance in AZIBs.
• Conventional synthesis methods often result in structural degradation.

Purpose of the Study:

• To develop a high-crystallinity layered MnO2 cathode material for AZIBs.
• To improve the structural integrity and cycling stability of MnO2 cathodes.
• To explore novel synthesis routes for advanced AZIB cathode materials.

Main Methods:

• High-temperature calcination of MnO2 at 800 °C.
• Morphological and structural characterization of the synthesized MnO2.
• Electrochemical performance testing of AZIBs using the synthesized cathode.

Main Results:

• High-crystallinity layered MnO2 (MnO2-cal) with ordered lamellar morphology was synthesized.
• MnO2-cal demonstrated superior cycling stability without Mn2+ additives.
• Reversible capacity of ~135 mAh g-1 with negligible capacity fading was achieved.
• Ex situ XRD and XAS confirmed reversible structural evolution and stable Mn-O coordination.

Conclusions:

• High-temperature calcination is an effective method for synthesizing robust MnO2 cathodes for AZIBs.
• The synthesized MnO2-cal exhibits enhanced structural integrity and electrochemical performance.
• This work offers a new perspective for developing long-life AZIB cathodes.