CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2020-0172569, filed on Dec. 10, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.

FIELD

One or more embodiments relates to an anode active material for a lithium secondary battery and a method of manufacturing the same, more particularly, to an anode active material including a carbon composite for a lithium secondary battery and a method of manufacturing the same.

BACKGROUND

Recently, as the demand for using lithium ion batteries in various applications such as small mobile devices and electric vehicles increases, there is a need to optimize the performance of lithium ion batteries according to various requirements for various application fields. In particular, for use in electric vehicles or energy storage systems (ESS), the development of active materials capable of fast charging and having high capacity is required.

The widely used graphite-based anode active material has high capacity and excellent cycle characteristics, but may have relatively low high-rate characteristics due to the layered crystal structure of graphite. Amorphous hard carbon is being studied as a candidate material for an anode active material capable of fast charging. Although amorphous hard carbon exhibits relatively excellent high rate characteristics, the amorphous hard carbon has a difficult problem in commercialization as a negative electrode active material of a lithium secondary battery in that it exhibits a relatively low capacity due to an amorphous crystal structure.

SUMMARY

One or more embodiments include an anode active material for a lithium secondary battery including a carbon composite having high capacity and excellent high rate characteristics.

One or more embodiments include a method of manufacturing an anode active material for a lithium secondary battery including a carbon composite having high capacity and excellent high rate characteristics.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.

An anode active material for a lithium secondary battery according to one or more embodiments is an anode active material including a carbon composite. The carbon composite may include a core particle including hard carbon; and a skin layer placed on a surface of the core particle, wherein the skin layer includes graphite particles attached to the surface of the core particle at a predetermined angle with respect to the surface and including graphite-based carbon material; and an amorphous carbon layer filling a space between the graphite particles and attaching the graphite particles to the surface of the core particle, and the carbon composite has a ratio of IDto IGin a range of 0.8 to 1.5 (0.8≤ID/IG≤1.5) in Raman analysis where IDis the intensity of D peak at 1300 cm−1to 1400 cm−1and IGis the intensity of G peak at 1500 cm−1to 1600 cm−1.

In an embodiment, 50% by weight or more of the graphite particles based on the total weight of the graphite particles may be attached at an angle of 20° to 90° with respect to the surface of the core particle.

In an embodiment, the carbon composite may exhibit a surface morphology that is not smooth by the graphite particles.

In an embodiment, based on the weight of the carbon composite, the core particle may be included in 30% by weight to 50% by weight, the graphite particles are included in 40% by weight to 60% by weight, and the amorphous carbon layer may be included in 10% by weight to 30% by weight.

In an embodiment, the carbon composite may have a particle diameter having a median value (D0.5) of about 10 μm to about 30 μm.

An anode active material for a lithium secondary battery according to one or more embodiments is an anode active material including a carbon composite. The carbon composite may include a core particle including hard carbon; a skin layer placed on a surface of the core particle, wherein the skin layer may include graphite particles attached to the surface of the core particle and including graphite-based carbon material; and an amorphous carbon layer filling a space between the graphite particles and attaching the graphite particles to the surface of the core particle, the carbon composite has a ratio of IDto IGin a range of 0.8 to 1.5 (0.8≤ID/IG≤1.5) in Raman analysis where IDis the intensity of D peak at 1300 cm−1to 1400 cm−1and IGis the intensity of G peak at 1500 cm−1to 1600 cm−1, and 50% by weight or more of the graphite particles based on the total weight of the graphite particles are attached at an angle of about 20° to about 90° with respect to the surface of the core particle.

In an embodiment, the carbon composite may exhibit a surface morphology that is not smooth by the graphite particles.

In an embodiment, based on the weight of the carbon composite, the core particle is included in 30% by weight to 50% by weight, the graphite particles may be included in 40% by weight to 60% by weight, and the amorphous carbon layer may be included in 10% by weight to 30% by weight.

In an embodiment, the carbon composite may have a particle diameter having a median value (D0.5) of about 10 μm to about 30 μm.

In an embodiment, the carbon composite may have a BET specific surface area of about 2 m2/g to about 8 m2/g.

The anode electrode active material for a lithium secondary battery according to one or more embodiments includes graphite particles attached to a core particle including amorphous hard carbon at a predetermined angle. Therefore, while high discharge capacity is obtained by the graphite particles, the movement path of lithium ions from the outside of the carbon composite to the core particle may be reduced compared to the case where the graphite particles completely surround the core particle, and accordingly, it may exhibit a high capacity even in fast charging and discharging. Accordingly, the anode active material for a lithium secondary battery may have high capacity and excellent high rate characteristics.

