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KR-102963883-B1 - ANODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR102963883B1KR 102963883 B1KR102963883 B1KR 102963883B1KR-102963883-B1

Abstract

The present invention relates to a negative electrode active material for a lithium secondary battery comprising silicon particles having a single particle form and a polycrystalline structure, having an average HS circularity of 0.875 or higher, and satisfying Formula 1 below. [Equation 1] Dv1 ≥ 2 μm In the above Equation 1, Dv1 is the particle size corresponding to 1% of the volume accumulation in the particle size distribution curve of silicon particles.

Inventors

  • 이동규
  • 이가을
  • 윤호철
  • 정지권

Assignees

  • (주)포스코퓨처엠

Dates

Publication Date
20260511
Application Date
20231024

Claims (10)

  1. It includes silicon particles having a single particle form and a polycrystalline structure, A negative electrode active material for a lithium secondary battery having an average HS circularity of 0.875 or higher and satisfying the following Equations 1, 3, and 4: [Equation 1] 2 μm ≤ Dv1 ≤ 2.55 μm [Equation 3] 7.30 μm ≤ Dv90 ≤ 7.57 μm [Equation 4] 0.82 ≤ [Dv90 - Dv10] / Dv50 ≤ 0.92 The above Dv1 is a particle size corresponding to 1% of the volume accumulation in the silicon particle size distribution curve, and The above Dv10 is a particle size corresponding to 10% of the volume accumulation in the silicon particle size distribution curve, and The above Dv50 is a particle size corresponding to 50% of the volume accumulation in the silicon particle size distribution curve, and The above Dv90 is the particle size corresponding to 90% of the volume accumulation in the particle size distribution curve of silicon particles.
  2. In paragraph 1, The above silicon particles are a negative electrode active material for a lithium secondary battery having an average aspect ratio of 0.695 or higher.
  3. In paragraph 1, The above silicon particles are a negative electrode active material for a lithium secondary battery satisfying Formula 2 below: [Equation 2] 0.70 ≤ [Dv50 - Dv10] / [Dv90 - Dv50] ≤ 0.80 In the above Equation 1, Dv50 is the particle size corresponding to 50% of the volume accumulation in the silicon particle size distribution curve, Dv10 is the particle size corresponding to 10% of the volume accumulation in the silicon particle size distribution curve, and Dv90 is the particle size corresponding to 90% of the volume accumulation in the silicon particle size distribution curve.
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  6. In paragraph 1, A negative electrode active material for a lithium secondary battery, wherein the volume average particle size (Dv50) of the silicon particles is 4 to 6 μm.
  7. In paragraph 1, A negative electrode active material for a lithium secondary battery having an average crystal grain size of 200 nm or less of the silicon particles.
  8. In paragraph 1, A negative electrode active material for a lithium secondary battery in which the Si purity of the above silicon particles is 98% or higher.
  9. A negative electrode for a lithium secondary battery comprising a negative electrode active material according to any one of claims 1 to 3 and claims 6 to 8.
  10. A lithium secondary battery comprising a negative electrode for a lithium secondary battery according to claim 9.

Description

Anode active material for lithium secondary battery and lithium secondary battery comprising the same The present invention relates to a negative electrode active material for a lithium secondary battery and a lithium secondary battery including the same. Lithium-ion batteries are currently the most widely used secondary battery systems in portable electronic communication devices, electric vehicles, and energy storage devices. These lithium-ion batteries are the focus of attention due to their advantages, such as high energy density, operating voltage, and a relatively low self-discharge rate, compared to commercial aqueous secondary batteries (Ni-Cd, Ni-MH, etc.). However, considering the need for more efficient usage time in portable devices and improved energy characteristics in electric vehicles, improvements in electrochemical properties remain technical challenges that need to be addressed. Consequently, extensive research and development are currently underway across the four major raw materials: the cathode, anode, electrolyte, and separator. Among these raw materials, graphite-based materials that exhibit excellent capacity retention characteristics and efficiency for the cathode have been commercialized. However, the reality is that the relatively low theoretical capacity value (LiC6: 372 mAh/g) and low discharge capacity ratio of graphite-based materials are somewhat insufficient to meet the high energy and high power density characteristics of batteries required by the market. Therefore, many researchers are interested in Group 4 elements (Si, Ge, Sn) of the periodic table, and among them, Si is particularly attracting attention as a very attractive material due to its very high theoretical capacity (Li15Si4: 3600 mAh/g) and low operating voltage (~0.1 V vs. Li/Li+). However, in the case of general silicon-based cathode materials, there is a problem that they are difficult to apply to actual batteries because they involve a volume change of up to 300% during the cycle, and due to the generation of fine particles caused by particle cracking and loss of electrical contact caused by continuous charging and discharging, the discharge capacity ratio and lifespan characteristics deteriorate significantly. In particular, silicon-based cathode materials are manufactured by grinding silicon metal raw material powder; however, needle-shaped or flake-shaped silicon particles may be generated during this grinding process. These needle-shaped or flake-shaped silicon particles cause poor uniformity in lithium ion reaction, leading to non-uniform volume expansion during cycling and accelerating the pulverization of silicon particles, which further degrades lifespan characteristics. Figure 1 is an SEM image of a negative electrode active material prepared according to Example 1. Terms such as first, second, and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention. The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and/or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and/or components. When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between. Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined. Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %. In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components. Hereinafter, embod