Negative electrode active material, negative electrode using the negative electrode active material and method for manufacturing negative electrode active material

A negative electrode for a lithium ion secondary battery, comprising:

• a negative electrode collector, and
• a negative electrode active material layer provided on the negative electrode collector, wherein
• the negative electrode active material layer includes a negative electrode active material,
• the negative electrode active material comprises:
• a graphite particle coated on a surface thereof with an amorphous carbon, and
• an insulating inorganic particle,
• the graphite particle has a pore with a pore size of 1 μm or less,
• the insulating inorganic particle has an average particle diameter (D50) of 14 nm or more and 100 nm or less,
• the insulating inorganic particle is present in the pore of the graphite particle, and
• the insulating inorganic particle is at least one selected from the group consisting of boehmite, alumina, and nanodiamond.

A method for manufacturing a negative electrode active material for a lithium ion secondary battery, comprising:

• a preparing step of preparing a paste including at least a graphite particle coated on a surface thereof with an amorphous carbon and an insulating inorganic particle;
• and
• a drying step of drying the prepared paste, wherein the graphite particle for use in the preparing step has a pore with a pore size of 1 μm or less,
• the insulating inorganic particle for use in the preparing step has an average particle diameter (D50) of 14 nm or more and 100 nm or less, and
• in the drying step, drying is performed such that the insulating inorganic particle is filled in the pore of the graphite particle to obtain the negative electrode active material which comprises the graphite particle coated on the surface thereof with the amorphous carbon and the insulating inorganic particle, wherein
• the graphite particle has the pore with the pore size of 1 μm or less,
• the insulating inorganic particle has the average particle diameter (D50) of 14 nm or more and 100 nm or less,
• the insulating inorganic particle is present in the pore of the graphite particle, and the insulating inorganic particle is at least one selected from the group consisting of boehmite, alumina, and nanodiamond.