MnO2kathoden

MnO2 cathode refers to a manganese dioxide-based positive electrode used in a range of battery chemistries, most notably zinc–manganese dioxide systems. It is a common, low-cost cathode material in alkaline and zinc-carbon primary cells, and it also appears in some rechargeable configurations. The cathode is typically formed as a composite with conductive carbon and a binder to create a porous electrode that can conduct electrons and accommodate ion transport.

MnO2 exists in several polymorphs, including alpha-, beta-, gamma-, and delta-MnO2, with structural differences affecting electrochemical performance. In practice, the beta form is common in many manganese dioxide cathodes, while other polymorphs and mixed phases can influence capacity, rate capability, and stability. The material is often nanostructured or mixed with dopants to improve conductivity and reversibility.

During discharge in alkaline Zn–MnO2 cells, MnO2 participates in a reduction to MnOOH, while the electrolyte (often potassium hydroxide) supplies the necessary hydroxide ions. A simplified reaction is MnO2 + H2O + e− → MnOOH + OH−, with the overall cell reaction Zn + 2 MnO2 + 2 H2O → Zn(OH)2 + 2 MnOOH. The exact pathways and products can vary with electrolyte composition, potential, and impurities. Charge and discharge performance are influenced by Mn dissolution, electrode impedance, and the structural stability of the MnO2 phase.

Material design emphasizes conductive composites, controlled porosity, and stabilization strategies to enhance reversibility and cycle life. MnO2 cathodes remain attractive for their abundance, safety, and cost, though their energy density and long-term cycle stability in rechargeable configurations are more limited compared to some other cathode chemistries.