POSITIVE ELECTRODE ACTIVE MATERIAL CONTAINING ABNORMAL OVERCHARGE PREVENTER AND LITHIUM SECONDARY BATTERY USING THE ACTIVE MATERIAL

摘要

PURPOSE: A positive electrode active material and a lithium secondary battery containing the active material are provided, to reduce the loss of capacity even in the case of abnormal overcharge by using a layered lithium manganese oxide. CONSTITUTION: The positive electrode active material comprises 100 parts by weight of a lithium transition metal oxide absorbing and desorbing a lithium ion; and 1-50 parts by weight of a layered lithium manganese oxide represented by LiMxMn(1-x)O2, wherein 0.05<=x<0.5; and M is at least one element selected from the group consisting of Cr, Al, Ni, Mn and Co. Preferably the layered lithium manganese oxide is LiCr0.1Mn0.9O2. The lithium secondary battery comprises a positive electrode containing the positive electrode active material; a negative electrode; a separator; and a nonaqueous electrolyte solution containing a lithium salt and an electrolyte. Preferably the layered lithium manganese oxide represented by LiMxMn(1-x)O2 is converted into a spinel-structured lithium manganese oxide represented by LiM2xMn(2-2x)O4 by initial charge/discharge.