Multifunctional Interfacial Engineering Enables Stable MnO₂ Cathodes for Aqueous Zinc-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable aqueous zinc-manganese dioxide (Zn-MnO2) batteries offer safe, low-cost, high-potential energy storage solutions.
• Challenges include unstable interface reactions and low electrical conductivity in MnO2 cathodes, hindering performance.
• Addressing these issues is crucial for advancing Zn-MnO2 battery technology for large-scale applications.

Purpose of the Study:

• To develop an interfacial engineering strategy for MnO2 cathodes in aqueous Zn-MnO2 batteries.
• To enhance electrochemical performance by stabilizing Mn2+/MnO2 chemistry and improving conductivity.
• To validate the practical viability of the engineered cathode for energy storage.

Main Methods:

• Fabrication of a dual-layer coating of ZIF-8 (outer) and polypyrrole (inner) on MnO2, termed ZPM.
• Characterization of the ZPM cathode's interfacial properties and electrochemical performance.
• Testing of coin cells and ampere-hour pouch cells to evaluate rate capability, cycling stability, and capacity.

Main Results:

• The ZIF-8 outer layer stabilized Mn2+ dissolution/deposition, while the polypyrrole inner layer formed a conductive network.
• The ZPM cathode exhibited exceptional rate performance and a prolonged lifespan of 5000 cycles with minimal attenuation (0.00925% per cycle at 10C).
• An ampere-hour pouch cell demonstrated a total capacity of 1068.4 mAh with a high areal capacity of 2.5 mAh cm-2.

Conclusions:

• The dual-layer interfacial engineering approach effectively addresses key limitations in aqueous Zn-MnO2 batteries.
• The ZPM cathode offers a promising pathway for developing high-performance, long-lasting rechargeable aqueous zinc batteries.
• This strategy provides valuable insights for optimizing electrode-electrolyte interfaces in similar energy storage systems.