Silicic acid-phosphoric acid compound, positive electrode for secondary battery, secondary battery, and production method thereof

摘要

Provided is a method for producing a silicic acid-phosphoric acid compound having improved controllability of composition and particle size. A1 + x + aMbSixP1-xO4 + c1 (the element A is at least one element selected from the group consisting of Li, Na and K, and the element M is at least one element selected from the group consisting of Fe, Mn, Co and Ni. A is −0.1 ≦ a ≦ 0.4, b is 0.7 ≦ b ≦ 1.3, x is 0.3 ≦ x 1.0, c1 is a number depending on the valence N of a, b and M And is a number that becomes c2 after the heating step.) After cooling the melt represented by (2) to obtain a solidified product, the solidified product is pulverized to obtain a pulverized product. The pulverized product is heated and expressed by A1 + x + aMbSixP1-xO4 + c2 (A, M, a, b and x have the same meaning as described above, and c2 is a number depending on the valence N of a, b and M). A silicic acid-phosphoric acid compound having a composition is produced.