Negative electrode active material for nonaqueous electrolyte secondary battery
There is provided a negative electrode active material for a nonaqueous electrolyte secondary battery, the negative electrode active material including a base particle containing Si and SiO 2 , a mixed phase coating that covers a surface of the base particle and contains SiO 2 and carbon, and a carbon coating that covers a surface of the mixed phase coating. The base particle is preferably formed of SiO X (0.5≤X≤1.5). The mixed phase coating preferably contains carbon dispersed in a phase formed of SiO 2 . The cycle characteristics of a nonaqueous electrolyte secondary battery including negative electrode active material particles containing Si and SiO 2 are improved.
1. A negative electrode active material particle used for a nonaqueous electrolyte secondary battery, the negative electrode active material particle comprising:
a base particle containing Si chemically bonded with SiO 2 ;
a mixed phase coating that covers a surface of the base particle and contains SiO 2 and carbon; and
a carbon coating that covers a surface of the mixed phase coating.
2. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein the base particle is formed of SiO X (0.5≤X≤1.5).
3. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein the mixed phase coating comprises carbon dispersed in a phase formed of SiO 2 .
4. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein the mixed phase coating consists-essentially SiO 2 and carbon.
5. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 4 , wherein the mixed phase coating has an average thickness of 0.005 μm to 1 μm.
6. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 5 , wherein the mixed phase coating covers 100% of the surface of the base particle.
7. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 6 , wherein the carbon coating covers 50% or more and 100% or less of a surface of a particle comprising the base particle and the mixed phase coating.
8. The negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 ,
wherein the base particle is formed of SiO X (0.5≤X≤1.5),
wherein the mixed phase coating comprises carbon dispersed in a phase formed of SiO 2 ,
wherein the mixed phase coating consists-essentially SiO 2 and carbon,
wherein the mixed phase coating has an average thickness of 0.005 μm to 1 μm,
wherein the mixed phase coating covers 100% of the surface of the base particle, and,
wherein the carbon coating covers 50% or more and 100% or less of a surface of a particle comprising the base particle and the mixed phase coating.