Preparation and Characterization of Layered Manganese Oxide (Birnessite) and Its Intercalation Reactions

Abstract

Layered manganese oxide (birnessite) was prepared by oxidation of Mn (NO3) 2 with H2O2 in NaOH solutions. The product had a composition of Na+0.44 (MnIII0.44MnIV0.56O2) 0.44-⋅0.5H2O and the negative charge of the host MnO2 layer due to MnIII was counterbalanced by Na+ in the interlayer. This Na-bimessite was treated with a hydrochloric acid solution to exchange Na+ with H+. The H-birnessite obtained was further treated with an n-propylamine solution, and the interlayer distance nearly doubled to 1.41 nm by the incorporation of propylammnonium ions (PA) . The PA-bimessite was suspended in a VCl3 solution, and V ions were intercalated. The V-birnessite had a composition of V5+0.08 (H0.3MnIII0.7MnIV0.3O2) 0.4-⋅0.3H2O, and it was found that the interlayer V ion was oxidized to 5+, possibly by MnIV in the host layer. This compound was expected to show better charge-discharge properties as a battery material than Na-bimessite, since multi-valent V5+ ions were likely to attract the layers more strongly and to support the layered structure more firmly.