Topic summary
Manganese dioxide
Manganese dioxide is the inorganic compound with the formulaMnO
2. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
2 is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery, although it is also used for other battery chemistries such as aqueouszinc-ion batteries.MnO
2 is also used as a pigment and as a precursor to other manganese compounds, such as potassium permanganate (KMnO4). It is used as a reagent in organic synthesis, for example, for the oxidation of allylicalcohols. MnO
2 has an α-polymorph that can incorporate a variety of atoms (as well as water molecules) in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
2 as a possible cathode for lithium-ion batteries.