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JP-7856327-B2 - All-solid-state lithium secondary battery and method for manufacturing the same

JP7856327B2JP 7856327 B2JP7856327 B2JP 7856327B2JP-7856327-B2

Inventors

  • テ・ゴン・キム
  • ミョン・ス・キム
  • ドン・チャン・イ
  • ジョン・ボム・イ
  • スル・チャム・キム
  • ヒェ・ジン・クォン
  • ヘ・ジン・ハー
  • キ・テ・キム
  • ソ・ヒ・キム
  • ジョン・ギル・キム

Assignees

  • エルジー エナジー ソリューション リミテッド

Dates

Publication Date
20260511
Application Date
20220527
Priority Date
20210528

Claims (12)

  1. It includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The negative electrode active material layer comprises a carbon structure and silver nanoparticles. The carbon structure includes a structure in which a plurality of graphene sheets are connected to each other, and the plurality of graphene sheets include two or more graphene sheets having different planar directions from each other. The average particle size of the silver nanoparticles is 1 nm to 50 nm. The silver nanoparticles are arranged on the surface of the carbon structure in a reduced-deposited state. The carbon structure is contained in the negative electrode active material layer at an amount of 50% to 98% by weight in an all-solid-state lithium secondary battery.
  2. In the carbon structure, The all-solid-state lithium secondary battery according to claim 1, wherein the average thickness of the graphene sheet is 0.34 nm to 10 nm.
  3. In the carbon structure, The all-solid-state lithium secondary battery according to claim 1, wherein the average maximum length of the graphene sheet is 10 nm to 500 nm.
  4. When performing Raman spectral measurements on the carbon structure, The all-solid-state lithium secondary battery according to claim 1, wherein the I / G ratio of the carbon structure is 0.9 to 2.0.
  5. The all-solid-state lithium secondary battery according to claim 1, wherein the specific surface area of the carbon structure is 200 m² /g to 1,100 m² /g.
  6. The all-solid-state lithium secondary battery according to claim 1, wherein the oxygen content of the carbon structure is 1% to 10% by weight relative to the total weight of the carbon structure.
  7. In the negative electrode active material layer, The all-solid-state lithium secondary battery according to claim 1, wherein the silver nanoparticles are present in an amount of 1% to 40% by weight relative to the total weight of the carbon structure and the silver nanoparticles.
  8. The all-solid-state lithium secondary battery according to claim 1, wherein the weight ratio of the carbon structure to the silver nanoparticles is 99:1 to 60:40.
  9. The all-solid-state lithium secondary battery according to claim 1, wherein the negative electrode active material layer further comprises a negative electrode binder.
  10. The all-solid-state lithium secondary battery according to claim 1, wherein the thickness of the negative electrode active material layer is 1 μm to 100 μm.
  11. Further including a negative electrode current collector, In the charged state, the material further includes a metal layer located between the negative electrode active material layer and the negative electrode current collector, The all-solid-state lithium secondary battery according to claim 1, wherein the metal layer contains lithium.
  12. A first step involves reducing the silver ions in a mixture of silver ions and a carbon structure to form a dry mixed powder containing the carbon structure and silver nanoparticles arranged on the carbon structure. A method for manufacturing an all-solid-state lithium secondary battery, comprising a second step of forming a negative electrode active material layer on a negative electrode current collector via a negative electrode mixture containing the aforementioned dried mixed powder, All-solid-state lithium secondary batteries, It includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The negative electrode active material layer comprises a carbon structure and silver nanoparticles. The carbon structure includes a structure in which a plurality of graphene sheets are connected to each other, and the plurality of graphene sheets include two or more graphene sheets having different planar directions from each other. The carbon structure is contained in the negative electrode active material layer in an amount of 50% to 98% by weight . A method for manufacturing all-solid-state lithium secondary batteries.

Description

This invention relates to an all-solid-state lithium secondary battery and a method for manufacturing the same. While secondary batteries have primarily been applied to small devices such as mobile devices and notebook computers, their application has recently expanded to medium and large-scale applications. For example, they are being used in fields requiring high energy and high output, such as energy storage systems (ESS) and electric vehicles (EVs). On the other hand, there has recently been a growing interest in all-solid-state lithium secondary batteries. These batteries use a non-flammable inorganic solid electrolyte instead of a liquid electrolyte. Compared to lithium secondary batteries using liquid electrolytes, they offer higher thermal stability, significantly reduce the risk of explosion due to leakage during overcharging, and eliminate the need for additional equipment to prevent such explosions, making them a subject of considerable interest. However, because all-solid-state lithium-ion batteries use a somewhat larger solid electrolyte, there are many attempts to improve the battery's energy density. For this purpose, a metal layer capable of forming an alloy with lithium, such as lithium metal, is used as the negative electrode active material layer. However, when such a metal layer is used, as the lithium deposited on the metal layer ionizes and dissolves, voids are created between the solid electrolyte and the metal layer, negatively affecting battery operation. Furthermore, during discharge, lithium metal is deposited dendritically from the surface of the metal layer, reducing the battery's lifespan and stability. To solve these problems, conventional methods have involved placing end plates at the positive and negative electrodes to prevent void formation and applying high external pressure. However, when using end plates to apply external pressure, the volume of the all-solid-state lithium secondary battery increases excessively, leading to a decrease in the energy density of the battery. Therefore, there is a need for new methods that can improve the lifespan and stability of all-solid-state lithium-ion batteries. This is a schematic diagram illustrating an all-solid-state lithium secondary battery according to one embodiment of the present invention.This is a schematic diagram illustrating an all-solid-state lithium secondary battery according to one embodiment of the present invention.This is a schematic diagram illustrating the carbon structure mentioned in the present invention.This is a TEM image of the carbon structure mentioned in the present invention.This is an SEM image of the carbon structure mentioned in the present invention.This is a TEM photograph of the carbon structure used in Manufacturing Example 1 of the present invention.This is a TEM photograph of the carbon structure used in manufacturing example 2 of the present invention.These are TEM images of the carbon structure used in Example 1 of the present invention and the silver nanoparticles placed on the carbon structure.This is an SEM image of the acetylene black used in Comparative Example 1 of the present invention. The terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention. The terms used herein are for illustrative purposes only and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “includes,” “equip,” or “have” should be understood to indicate the presence of implemented features, figures, steps, components, or combinations thereof, without prejudice to the existence or possibility of adding one or more other features, figures, steps, components, or combinations thereof. In this specification, "specific surface area" is measured by the BET method, and specifically, it can be calculated from the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77 K) using a BELSORP-mini II manufactured by BEL Japan. The I / G ratio described herein can be measured from the wavelength-peak graph during Raman spectral measurement. Specifically, after setting a baseline so that the D peak and G peak can be distinguished and adjusting the graph (fitting), the I / G ratio can be confirmed by dividing the D peak intensity by the G peak intensity (using embedded software, NRS-2000B, manufactured by Jasco). In the Raman spectrum, the G peak around 1590 cm⁻¹ originates from the E 2g vibrational mode of the carbon sp₂ bond, and the D peak around 1350 cm⁻¹ appears when a defect is present in the carbon sp₂ bond. In this specification, the average thickness of the graphene sheets within the carbon structure i