Engineering Aqueous Zn-MnO2 Microbatteries Using a Synergistic Reaction Mechanism

Aqueous Zn-MnO2 microbatteries (MBs) have received significant research attention due to their safety, thinness, flexibility, and high energy density. However, poor cycling stability, controversial reaction mechanisms, and complex fabrication processes have limited their development and application. In this study, aqueous Zn-MnO2 MBs with a high volumetric energy density (1037.5 mWh cm–3), areal specific capacity (1777.5 μAh cm–2), and excellent cycling stability were successfully manufactured. This was achieved by adding Mn2+ to the electrolyte and combining it with a low-cost, short-process, and customizable patterned laser direct writing technique. The excellent properties stem from the following synergistic reaction mechanisms. (i) The addition of Mn2+ to the electrolyte inhibits the dissolution of the cathode material, and (ii) based on the traditional Mn3+/MnO2 redox conversion, the added Mn2+ can promote the electrodeposition reaction conversion process of Mn2+/MnO2, thus supplementing the cathode material and improving the capacity and cycling stability. In addition, we successfully manufactured zinc-ion hybrid microsupercapacitors and activated carbon-based microsupercapacitors with excellent performance, demonstrating the scalability of laser direct writing technology. This work proposes a synergistic reaction mechanism for aqueous Zn-MnO2 batteries; it provides a perspective for constructing MBs with excellent electrochemical properties.