POSITIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERIES, ELECTRODE PASTE FOR LITHIUM ION SECONDARY BATTERIES, AND LITHIUM ION SECONDARY BATTERY

An object of the present invention is to obtain a lithium ion battery that has high safety and a high energy density and allows estimation of the remaining capacity of the battery from the discharge voltage, and the present invention provides a positive electrode for lithium ion secondary batteries that includes a lithium iron phosphate particle, a lithium iron manganese phosphate particle, and a layered oxide-based active material particle at a weight ratio of x:y:z, wherein 0.10≤x≤0.60, 0.10≤y≤0.70, 0.10≤z≤0.40, and x+y+z=1, and provides a lithium ion secondary battery characterized in that a discharge curve indicating a relationship between a discharge voltage and a discharge capacity of the lithium ion secondary battery has one non-plateau region between two plateau regions, and a width of the non-plateau region is 20% or more in terms of a state of charge (SOC).