Nonaqueous electrolyte secondary battery
AssigneeSanyo Electric Co., Ltd.
InventorsYasufumi Takahashi, Hiroyuki Fujimoto, Akira Kinoshita, Toyoki Fujihara, Shingo Tode, Ikuro Nakane, Shin Fujitani
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Abstract
A nonaqueous electrolyte secondary battery comprising a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and a nonaqueous electrolyte is characterized in that the positive electrode active material is composed of a lithium trasition metal oxide having a layer structure and containing Li and Co and further contains a group IVA element and group IIA element of the periodic table.
Claims12
1-18. (canceled)
In a nonaqueous electrolyte secondary battery including a positive electrode containing a positive active material, a negative electrode containing a negative active material and a nonaqueous electrolyte,
- said secondary battery being characterized in that said positive active material comprises lithium cobaltate in which Zr and Mg are contained by mixing their source materials in the preparation of the positive active material by a heat treatment;
- said Zr and Mg are contained in said lithium cobaltate in the total amount of not greater than 3 mole %, based on the total amount of the aforementioned elements and cobalt present in the lithium cobaltate;
- a Zr-containing compound after the heat treatment exists in the form of particles sintered with particle surfaces of the lithium cobaltate;
- and Zr is detected in the particles of the Zr-containing compound but not detected in the lithium cobaltate particles.
A method of using a nonaqueous electrolyte secondary battery characterized in that a nonaqueous electrolyte secondary battery including a positive electrode containing a positive active material, a negative electrode containing a negative active material other than metallic lithium and a nonaqueous electrolyte is charged at an end-of-charge voltage of at least 4.3 V, said positive active material comprising lithium cobaltate in which Zr and Mg are contained by mixing their source materials in the preparation of the positive active material by a heat treatment, said Zr and Mg being contained in said lithium cobaltate in the total amount of not greater than 3 mole %, based on the total amount of the aforementioned elements and cobalt present in the lithium cobaltate, said Zr after the heat treatment being present in the form of particles of a Zr-containing compound that are sintered with particle surfaces of the lithium cobaltate, and said Zr is detected in the particles of the Zr-containing compound but not detected in the lithium cobaltate particles.
Dependencies are inferred from the claim text.