Lithium transition metal oxide

A method of making an essentially layered lithium transition metal oxide compound comprising lithium cations, transition metal cations T and oxygen anions, the T cations being selected from Co cations and mixtures of Co cations and Ni cations in which mixtures the Ni cations make up a minor proportion of at most 25% of the T cations and the compound being in accordance with the formula:

• Li.sub.x TO.sub.y
• wherein x is greater than or equal to 0.4 and less than or equal to 1.4, and y is greater than or equal to 1.7 and less than or equal to 2.7, the transition metal cations having an average valency of from +3 to +4, the compound having its O anions arranged in layers in a substantially cubic-close packed arrangement, with its Li cations being arranged in layers and its T cations occupying octahedral sites and being arranged in layers, each layer of the Li cations being sandwiched between two layers of the O anions and each said layer of O anions being sandwiched between a said layer of Li cations and a layer of T cations, 75%-99.8% of the T cations in the compound being located in the layers of T cations, and the remainder of the T cations being located in the layers of Li cations, the compound being characterized in that it has an X-ray diffraction trace using CuK.sub.a radiation which has a single peak between 65.degree.2.THETA. and 67.degree. 2.THETA., which method comprises the steps of:
• intimately mixing together in finely divided solid form a lithium constituent comprising at least one compound of lithium selected from the salts, oxides or hydroxides of lithium, and a transition metal constituent comprising at least one compound of a transition metal T, selected from the salts, oxides and hydroxides of Co and of mixtures of Co and Ni, to form a starting mixture, and
• heating the starting mixture to a temperature of 200.degree.-600.degree. for a period of at least 12 hours, at least part of the heating being under a oxygen-containing oxidizing atmosphere and the proportions of said lithium constituent and said transition metal constituent which are mixed together being selected so that, in the lithium transition metal oxide compound produced, the transition metal cations have a valency of from +3 to +4.

A method of making an essentially layered lithium transition metal oxide compound comprising lithium cations, transition metal cations T and oxygen anions, the T cations being selected from Co cations and mixtures of Co cations and Ni cations in which mixtures the Ni cations make up a minor proportion of at most 25% of the T cations and the compound being in accordance with the formula:

• Li.sub.x TO.sub.y
• wherein x is greater than or equal to 0.4 and less than or equal to 1.4, and y is greater than or equal to 1.7 and less than or equal to 2.7, the transition metal cations having an average valency of from +3 to +4, the compound having its O anions arranged in layers in a substantially cubic-close packed arrangement, with its Li cations being arranged in layers and its T cations occupying octahedral sites and being arranged in layers, each layer of the Li cations being sandwiched between two layers of the O anions and each said layer of O anions being sandwiched between a said layer of Li cations and a layer of T cations, 75%-99.8% of the T cations in the compound being located in the layers of T cations, and the remainder of the T cations being located in the layers of Li cations, the compound being characterized in that it has an X-ray diffraction trace using CuK.sub.a radiation which has a single peak between 65.degree.2.THETA. and 67.degree. 2.THETA., which method comprises the steps of:
• intimately mixing together in finely divided form a lithium constituent comprising at least one compound of lithium selected from the salts, oxides or hydroxides of lithium, and a transition metal constituent comprising at least one compound of a transition metal T, selected from the salts, oxides and hydroxides of Co and mixtures of Co and Ni, to form a starting mixture, the mixing being effected by mixing a solution of the lithium constituent with a solution of the transition metal constituent, followed by recrystallization of a mixture of the constituents from the starting mixture, and
• heating the starting mixture to a temperature of 200.degree.-600.degree. C. for a period of at least 5 hours, at least part of the heating being under a oxygen-containing oxidizing atmosphere and the proportions of said lithium constituent and said transition metal constituent which are mixed together being selected so that, in the lithium transition metal oxide compound produced, the transition metal cations have a valency of from +3 to +4, and the ratio of transition metal cations:lithium cations is 2:1-2.5:1.