US-12626907-B2 - Anode active material for lithium secondary battery and lithium secondary battery including the same

US12626907B2US 12626907 B2US12626907 B2US 12626907B2US-12626907-B2

Abstract

An anode active material for a secondary battery according to an embodiment of the present invention includes a silicon-based active material, and a graphite-based active material including secondary particles in which a plurality of primary particles are assembled. A ratio of an arithmetic average value of perimeters of the secondary particles relative to a volume average particle diameter (D50) of the secondary particles is maintained within a predetermined range.

Inventors

Chan Young Jeon
So Hyun Park
Kyung Hoon Kim

Assignees

SK ON CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20230201
Priority Date: 20220207

Claims (15)

1 . An anode active material for a lithium secondary battery, comprising: a silicon-based active material; and a graphite-based active material comprising secondary particles in which a plurality of primary particles are assembled and satisfying Equation 1: 4.5≤ P/D≤ 9.5 [Equation 1] wherein, in Equation 1, P is an arithmetic average value of perimeters of the secondary particles measured by a particle image analyzer, and D is a volume average particle diameter (D50) of the secondary particles, and wherein the arithmetic average value of the perimeters of the secondary particles measured by the particle image analyzer is in a range from 10 μm to 150 um.
2 . The anode active material for a lithium secondary battery according to claim 1 , wherein a ratio of the volume average particle diameter (D 50 ) of the secondary particles relative to a volume average particle diameter (D 50 ) of the primary particles is 1.8 or less.
3 . The anode active material for a lithium secondary battery according to claim 2 , wherein the ratio of the volume average particle diameter of the secondary particles to the volume average particle diameter of the primary particles is 1.2 to 1.8.
4 . The anode active material for a lithium secondary battery according to claim 2 , wherein the primary particles have a volume average particle diameter in a range from 1 μm to 10 μm.
5 . The anode active material for a lithium secondary battery according to claim 1 , wherein the volume average particle diameter of the secondary particles is in a range from 5 μm to 20 μm.
6 . The anode active material for a lithium secondary battery according to claim 1 , wherein a specific surface area of the graphite-based active material measured by a BET method is in a range from 0.5 m 2 /g to 5 m 2 /g.
7 . The anode active material for a lithium secondary battery according to claim 1 , wherein the graphite-based active material includes artificial graphite.
8 . The anode active material for a lithium secondary battery according to claim 1 , wherein the graphite-based active material further comprises a carbon coating covering at least a portion of a surface of each of the secondary particles.
9 . The anode active material for a lithium secondary battery according to claim 8 , wherein a content of the carbon coating is in a range from 0.5 wt % to 6 wt % based on a total weight of the graphite-based active material.
10 . The anode active material for a lithium secondary battery according to claim 8 , wherein a ratio of a specific surface area of the graphite-based active material relative to a specific surface area of the secondary particles is in a range from 0.3 to 0.99.
11 . The anode active material for a lithium secondary battery according to claim 8 , wherein the carbon coating includes amorphous carbon.
12 . The anode active material for a lithium secondary battery according to claim 1 , wherein the silicon-based active material includes silicon (Si) or silicon oxide (SiOx, 0<x<2).
13 . The anode active material for a lithium secondary battery according to claim 1 , wherein a content of the silicon-based active material is in a range from 1 wt % to 50 wt %, and a content of the graphite-based active material is in a range from 50 wt % to 99 wt %, based on a total weight of the anode active material for a lithium secondary battery.
14 . The anode active material for a lithium secondary battery according to claim 1 , wherein a pressed density is 1.2 g/cc or more when pressed at a pressure of 10 MPa.
15 . A lithium secondary battery, comprising: an anode comprising the anode active material for a lithium secondary battery according to claim 1 ; and a cathode facing the anode.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application No. 10-2022-0015681 filed on Feb. 7, 2022 in the Korean Intellectual Property Office (KIPO), the entire disclosure of which is incorporated by reference herein. BACKGROUND 1. Field The present invention relates to an anode active material for a lithium secondary battery and a lithium secondary battery including the same. More particularly, the present invention relates to an anode active material for a lithium secondary battery including different types of materials and a lithium secondary battery including the same. 2. Description of the Related Art A secondary battery which can be charged and discharged repeatedly has been widely employed as a power source of a mobile electronic device such as a camcorder, a mobile phone, a laptop computer, etc., according to developments of information and display technologies. The secondary battery includes, e.g., a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery is highlighted due to high operational voltage and energy density per unit weight, a high charging rate, a compact dimension, etc. For example, the lithium secondary battery may include an electrode assembly including a cathode, an anode and a separation layer (separator), and an electrolyte immersing the electrode assembly. The lithium secondary battery may further include an outer case having, e.g., a pouch shape for accommodating the electrode assembly and the electrolyte. For example, the anode may include a carbon-based active material or silicon-based active material particles as an anode active material. However, when the battery is repeatedly charged/discharged, mechanical and chemical damages of particle cracks may be caused due to operational conditions at high temperature and humidity and the repeated charging/discharging. For example, cracks may occur at an active material particle surface, a contact property between the active material particles may be deteriorated due to a volume change of the active material particles, and a short-circuit of the anodes may occur. If a composition and a structure of the anode active material are changed to improve stability of the active material particles, an ion and electron conductivity may be degraded and a power of the secondary battery may be deteriorated. Thus, developments of the anode active material capable of enhancing life-span stability and power/capacity properties are needed. For example, Korean Published Patent Application No. 2017-0099748 discloses an electrode assembly for a lithium secondary battery and a lithium secondary battery including the same. SUMMARY According to an aspect of the present invention, there is provided an anode active material for a lithium secondary battery having improved stability and electrical property. According to an aspect of the present invention, there is provided a secondary battery having improved stability and electrical property. An anode active material for a secondary battery includes a silicon-based active material, and a graphite-based active material including secondary particles in which a plurality of primary particles are assembled and satisfying Equation 1. 4.5≤P/D≤9.5 [Equation 1] In Equation 1, P is an arithmetic average value of perimeters of the secondary particles measured by a particle image analyzer, and D is a volume average particle diameter (D50) of the secondary particles. In some embodiments, a ratio of the volume average particle diameter (D50) of the secondary particles relative to a volume average particle diameter (D50) of the primary particles may be 1.8 or less. In some embodiments, the ratio of the volume average particle diameter of the secondary particles to the volume average particle diameter of the primary particles may be in a range from 1.2 to 1.8. In some embodiments, the primary particles may have a volume average particle diameter in a range from 1 μm to 10 μm. In some embodiments, the volume average particle diameter of the secondary particles may be in a range from 5 μm to 20 μm. In some embodiments, the arithmetic average value of the perimeters of the secondary particles measured by the particle image analyzer may be in a range from 10 μm to 150 μm. In some embodiments, a specific surface area of the graphite-based active material measured by a BET method may be in a range from 0.5 m2/g to 5 m2/g. In some embodiments, the graphite-based active material may include artificial graphite. In some embodiments, the graphite-based active material may further include a carbon coating covering at least a portion of a surface of each of the secondary particles. In some embodiments, a content of the carbon coating may be in a range from 0.5 wt % to 6 wt % based on a total weight of the graphite-based active material. In some embodiments, a ratio of a specific surface area of the graphite-based active material rel