Technology Finance Corporation (proprietary) Limited

Csir

Margaretha H Rossouw

Michael M Thackeray

The invention provides a manganese dioxide-based material which is highly crystalline and chemically prepared. The material has a predominantly ramsdellite structure, and has a powder X-ray diffraction pattern (CuK.sub..alpha. radiation) in which the ratio of a [110] peak height to a [201] peak height is at least 0,6:1,0. The material can be used as an electrode material in an electrochemical cell 10.

Manganese dioxide-based material

The invention provides a hydrogen manganese oxide compound. It has manganese cations and oxygen anions arranged in a framework having a hollandite-type structure and defining channels. Cations in the channels are confined to manganse, hydrogen and/or lithium cations. The ionic ratios of lithium:manganese cations and of hydrogen:manganese cations are respectively at most 0.05:1 and at least 0.01:1.00. The invention also provides a method of making said compound; a lithium manganese oxide compound derived from said hydrogen manganese oxide compound and a method of synthesising it therefrom; and electrochemical cells employing said hydrogen manganese oxide and lithium manganese oxide compounds as active cathode materials.

Manganese oxide compounds

The invention provides a novel lithium manganese oxide compound in which oxygen anions, lithium cations and manganese cations are arranged in layers, each layer of lithium cations being sandwiched between two layers of oxygen anions, each layer of manganese cations being sandwiched between two layers of oxygen anions and each layer of oxygen anions being sandwiched between a layer of lithium cations and a layer of manganese cations. The invention also provides a method of making the compound; and an electrochemical cell employing the compound as its cathode.

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Pretoria, South Africa

Margaretha H Rossouw