LITHIUM ION SECONDARY BATTERY

摘要

A lithium ion secondary battery which is provided with a positive electrode, a negative electrode, and a separator that is arranged between the positive electrode and the negative electrode. The positive electrode is provided with a positive electrode active material layer that contains a positive electrode active material, and the positive electrode active material is a lithium-containing metal oxide having a unit lattice represented by general formula (1) LiFe1-xZrxP1-ySiyO4 (wherein 0 < x < 1 and 0 < y < 1). The unit lattice has lattice constants of 10.326 ≤ a ≤ 10.335, 6.006 ≤ b ≤ 6.012 and 4.685 ≤ c ≤ 4.714. The separator has a void fraction that is equal to or larger than that of the positive electrode active material layer.