Compound, method for preparation of the same, and lithium secondary battery comprising the same
View Patent ↗Disclosed are a novel compound, a method for preparing the same, and a lithium secondary battery comprising the same. More specifically, disclosed are a compound in which five MO 6 octahedrons are bonded to one another around one MO 6 octahedron such that the MO 6 octahedrons share a vertex, to form hollows and Li cations substituted instead of Na cations using an ion substitution method are present in the hollows, and a crystal structure thereof is not varied even upon intercalation and deintercalation of Li cations, a method for preparing the same, and a lithium secondary battery comprising the same as a cathode active material.
1. At least one compound selected from compounds represented by the following Formula 1:
Li x Na 1-x Ru 2-y Me y O 4 (1)
wherein
0<x≦1;
0<y≦2; and
Me is a metal or transition metal cation having an oxidation number of +2 to +4, and
wherein the compound has a crystal structure in which five RuO 6 octahedrons are bonded to one another around one RuO 6 octahedron such that the RuO 6 octahedrons share a vertex to form hollows and Na cations and Li cations coexist in the hollows.
2. The compound according to claim 1 , wherein x is 1.
3. The compound according to claim 1 , wherein Me is at least one selected from the group consisting of Al, Mg, Ti, Fe, Co, Ni and Mn.
4. The compound according to claim 1 , wherein the oxygen ion of Formula 1 is substituted by an anion (A) having an oxidation number of −1 or −2.
5. The compound according to claim 4 , wherein the compound is represented by the following formula 2:
Li x Na 1-x Ru 2-y Me y O 4-z A z (2)
wherein
0<x≦1;
0<y≦2;
0≦z≦0.1;
Me is a metal or transition metal cation having an oxidation number of +2 to +4; and
A is an anion having an oxidation number of −1 or −2.
6. The compound according to claim 5 , wherein A is at least one selected from the group consisting of halogen, S and N.