Active material with a surface-modified layer covering a metal oxide core and an electrode and battery comprising the same
View Patent ↗An active material with a sufficient cycle characteristic and a process for its production are provided. According to the process for production of an active material of this invention, an aqueous solution containing a metal fluorocomplex is contacted with a metal oxide to form a surface-modified layer on the surface of the metal oxide. The active material of the invention comprises a core section made of a metal oxide and a surface-modified layer covering the core section, wherein the surface-modified layer is an oxide containing a metal present in the core section and a metal not present in the core section.
1. An active material provided with:
a core section composed of LiCo 1/3 Ni 1/3 Mn 1/3 O 2 and
a surface-modified layer covering the core section, wherein:
the surface-modified layer has a first layer composed of an oxide containing a metal present in the core section, titanium, and fluorine;
the fluorine is only present in an upper surface of the surface-modified layer;
the upper surface of the surface-modified layer has a thickness of from 1 to 4 nm; and
the surface-modified layer has a thickness of from 10 to 30 nm.
2. The active material according to claim 1 , wherein a content of the titanium is 0.01 mol %-10 mol % with respect to the entire active material.
3. The active material according to claim 1 , wherein:
a content of the titanium is 0.1 mol %-70 mol % with respect to a total number of moles of Co, Ni, and Mn in the surface-modified layer and the titanium.
4. An electrode comprising the active material according to claim 1 .
5. A battery provided with an electrode comprising the active material according to claim 1 .
6. The active material according to claim 1 , wherein the surface-modified layer further has a second layer composed of an oxide containing a metal present in the core section and a metal not present in the core section, the second layer being between the core section and the first layer.
7. The active material according to claim 1 , wherein the surface-modified layer is formed on a surface of LiCo 1/3 Ni 1/3 Mn 1/3 O 2 by contacting an aqueous solution containing a metal fluorocomplex with LiCo 1/3 Ni 1/3 Mn 1/3 O 2 .
8. A process for production of the active material of claim 1 , whereby an aqueous solution containing a metal fluorocomplex is contacted with LiCo 1/3 Ni 1/3 Mn 1/3 O 2 to form a surface-modified layer on the surface of the LiCo 1/3 Ni 1/3 Mn 1/3 O 2 .
9. The process according to claim 8 , wherein the metal fluorocomplex is at least one selected from the group consisting of fluorotitanic acid and fluorotitanic acid salts.
10. The process according to claim 1 , wherein the aqueous solution containing the metal fluorocomplex further comprises a scavenger that chemically scavenges fluoride ion from the metal fluorocomplex.
11. The process according to claim 10 , wherein the scavenger is boric acid or aluminum.