Jfe Steel Corporation

Jfe Chemical Corporation

Ryota Yamaji

Akira Matsuzaki

Yusuke Fushiwaki

Mikito Suto

Ryuta Haga

Yasushi Madokoro

Provided is spherically-shaped coated graphite exhibiting excellent cycle capacity-maintaining property when used as a negative electrode material for a lithium ion secondary battery. The spherically-shaped coated graphite includes: spherically-shaped graphite in which primary particles with an equivalent spherical diameter of not more than 0.8 &#x3bc;m have a volume ratio of more than 40.0% and not more than 70.0%, and primary particles with an equivalent spherical diameter of not less than 1.5 &#x3bc;m and not more than 3.0 &#x3bc;m have a volume ratio of not less than 3.0% and not more than 17.0%, in a particle size distribution of primary particles obtained using X-ray computed tomography; and a carbonaceous substance covering the spherically-shaped graphite, and a pore volume of pores with a pore size of 7.8 nm to 36.0 nm is not more than 0.017 cm/g, and a mass of infiltrated dibutyl phthalate is less than 0.70 g/cm.

Spherically-shaped coated graphite, negative electrode for lithium ion secondary battery, and lithium ion secondary battery

Provided are carbonaceous substance-coated graphite particles that include: graphite particles; and carbonaceous coatings covering at least part of surfaces of the graphite particles, the carbonaceous substance-coated graphite particles have a maximum particle diameter of 30.0 to 90.0 &#x3bc;m, a pore volume Vof pores with a pore size of 7.8 to 36.0 nm is 0.009 to 0.164 cm/g, and in a pore size distribution graph with the pore size being plotted on a horizontal axis and a dV/dP value obtained by differentiating the pore volume with the pore size being plotted on a vertical axis, a pore size Pwith which the dV/dP value is maximized is 2.5 to 5.5 nm.

Carbonaceous substance-coated graphite particles, negative electrode for lithium ion secondary battery and lithium ion secondary battery

Provided is carbonaceous substance-coated graphite particles that exhibit excellent battery properties when used as a negative electrode material for a lithium ion secondary battery. The carbonaceous substance-coated graphite particles includes: graphite particles; and carbonaceous coatings covering at least part of surfaces of the graphite particles, and the carbonaceous substance-coated graphite particles have a specific surface area Sdetermined by BET method of 4.0 to 15.0 m/g, and a pore volume Vof pores with a pore size of 7.8 to 36.0 nm is 0.001 to 0.026 cm/g, and in a pore size distribution graph with the pore size being plotted on a horizontal axis and a dV/dP value obtained by differentiating the pore volume with the pore size being plotted on a vertical axis, a pore size Pwith which the dV/dP value is maximized is 2.5 to 5.5 nm.

Growing community of inventors

Tokyo, Japan

Ryota Yamaji