Layered structure manganese dioxide for cathode material in lithium rechargeable cell and process for producing the same

Abstract

A layered structure manganese dioxide (MnO2) of which oxide lattices are in the pattern of pseudo-hexagonal close packing ( . . . AABB . . . ) and has hexagonal P63/mmc space group or orthorhombic Cmcm space group. The present invention also provides a process for producing said layered structure manganese dioxide (MnO2) which comprises heat treating a mixture of an alkali metal compound and a manganese compound at a high temperature. During the process, bismuth compounds or lead compounds may be added in order to stabilize the layered crystal structure of MnO2, or lithium compounds may be added in order to improve the reversibility of charge and discharge. The layered structure MnO2 is suitable for use as a cathode material in lithium rechargeable cells, since it does not transform into a spinel phase during charge and discharge cycling, thus having an excellent charging and discharging reversibility.

Dependencies are inferred from the claim text.