EP-4742322-A1 - ANODE, MANUFACTURING METHOD THEREFOR, AND ELECTROCHEMICAL DEVICE COMPRISING SAME

EP4742322A1EP 4742322 A1EP4742322 A1EP 4742322A1EP-4742322-A1

Abstract

Disclosed are a negative electrode including a current collector; and a negative electrode active material layer located on at least one surface of the current collector and including granulated particles and a second binder, wherein the second binder holds and connects the granulated particles together, wherein the granulated particles include a negative electrode active material, a conductive material and a first binder, wherein the first binder connects and holds the negative electrode active material and the conductive material together, a method for manufacturing the same, and an electrochemical device including the same.

Inventors

SHIN, Min-Seon
SUNG, Nak-Gi

Assignees

LG Energy Solution, Ltd.

Dates

Publication Date: 20260513
Application Date: 20240802

Claims (20)

A negative electrode comprising: a current collector; and a negative electrode active material layer located on at least one surface of the current collector and including granulated particles and a second binder, wherein the second binder holds and connects the granulated particles together, wherein the granulated particles include a negative electrode active material, a conductive material and a first binder, wherein the first binder connects and holds the negative electrode active material and the conductive material together.
The negative electrode according to claim 1, wherein the negative electrode active material includes a silicon-based active material alone, or a mixture of the silicon-based active material with a carbon-based active material.
The negative electrode according to claim 2, wherein the silicon-based active material includes silicon (Si), a silicon oxide (SiOx (0<x≤2), a silicon carbide (SiC), a silicon-based alloy (M x Si y , M:Ni,Ti,Fe,Zr,Nb) or two or more of them.
The negative electrode according to claim 2, wherein the carbon-based active material includes natural graphite, artificial graphite, graphene, or two or more of them.
The negative electrode according to claim 1, wherein the conductive material includes a linear shaped conductive material, a point shaped conductive material, or two or more of them.
The negative electrode according to claim 5, wherein the linear shaped conductive material includes carbon nanotubes, carbon nanofibers, graphene, or two or more of them.
The negative electrode according to claim 5, wherein the point shaped conductive material includes carbon black, Denka black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, or two or more of them.
The negative electrode according to claim 1, wherein the first binder includes a diene-based polymer, an acrylate-based polymer, a styrene-based polymer, a polyacrylonitrile-based polymer, a vinyl-based polymer, a polyoxide-based polymer, a polyacrylamide or two or more of them.
The negative electrode according to claim 1, wherein the second binder includes a diene-based polymer, an acrylate-based polymer, a styrene-based polymer, or two or more of them.
The negative electrode according to claim 1, wherein an amount of the negative electrode active material is from 80 parts by weight to 99 parts by weight, an amount of the conductive material is from 0.001 parts by weight to 0.5 parts by weight, and an amount of the first binder is from 0.1 parts by weight to 2 parts by weight, based on 100 parts by weight of the granulated particles.
The negative electrode according to claim 1, wherein an average particle size (D50) of the granulated particles is from 10 µ m to 20 µ m.
The negative electrode according to claim 2, wherein the negative electrode active material includes the mixture of the silicon-based active material and the carbon-based active material, and an amount of the silicon-based active material is from 5 parts by weight to 25 parts by weight based on 100 parts by weight of the carbon-based active material.
The negative electrode according to claim 1, wherein the negative electrode active material layer further includes an additional carbon-based active material, an additional conductive material or both.
The negative electrode according to claim 13, wherein the negative electrode active material layer includes 100 parts by weight of the granulated particles, 80 parts by weight to 99 parts by weight of the additional carbon-based active material, 0.01 parts by weight to 2 parts by weight of the additional conductive material, and 1 part by weight to 4 parts by weight of the second binder.
A method for manufacturing the negative electrode according to claim 1, the method comprising the steps of: drying a composition including the negative electrode active material, the conductive material, the first binder and a first water-based dispersion medium by a spray drying method to manufacture the granulated particles; mixing the granulated particles with the second binder and a second water-based dispersion medium to prepare a negative electrode slurry; and coating the negative electrode slurry on the at least one surface of the current collector, drying and rolling to form the negative electrode active material layer.
The method for manufacturing the negative electrode according to claim 15, wherein the negative electrode active material includes a silicon-based active material alone, or a mixture of the silicon-based active material with a carbon-based active material.
The method for manufacturing the negative electrode according to claim 15, wherein the negative electrode slurry further includes an additional carbon-based active material, an additional conductive material, or both.
The method for manufacturing the negative electrode according to claim 15, wherein the spray drying method includes spraying and drying the slurry in hot air, and a temperature of the fed hot air ranges from 130°C to 210°C.
An electrochemical device comprising the negative electrode according to any one of claims 1 to 14.
The electrochemical device according to claim 19, wherein the electrochemical device is a secondary battery.

Description

TECHNICAL FIELD The present disclosure relates to a negative electrode, a method for manufacturing the same and an electrochemical device including the same. The present application claims priority to Korean Patent Application No. 10-2023-0101869 filed on August 3, 2023 in the Republic of Korea, the disclosure of which is incorporated herein by reference. BACKGROUND Due to the increasing use of fossil fuels, there is a growing demand for the use of alternative energy and clean energy, and in such circumstances, many studies are being made in the field of energy generation and storage using electrochemistry. Currently, a typical example of electrochemical devices using electrical and chemical energy is secondary batteries, and the range of application of secondary batteries is gradually expanding. The most common secondary batteries are lithium secondary batteries, and lithium secondary batteries are used as not only an energy source of mobile devices but also a power source of electric vehicles and hybrid electric vehicles as an alternative to vehicles using fossil fuels such as gasoline vehicles and diesel vehicles that are regarded as one of the main causes of air pollution, and they have a diverse range of applications including use as an auxiliary power source via a grid. A lithium secondary battery has a structure in which an electrode assembly including a positive electrode and a negative electrode, each having an active material coating on an electrode current collector with a porous separator interposed between the positive electrode and the negative electrode is impregnated with an electrolyte including a lithium salt, and the electrode is manufactured by coating a slurry in which an active material, a binder and a conductive material are dispersed in a solvent on the current collector, drying and roll pressing. Additionally, the basic performance characteristics of the lithium secondary battery, capacity, output and life are greatly affected by the negative electrode material. To maximize the performance of the battery, the negative electrode active material needs to fulfill the requirements that the electrochemical reaction potential is close to lithium metal, reaction reversibility with lithium ions is high and the diffusion rate of lithium ions in the active material is high. Carbon-based materials that have been primarily used to manufacture negative electrodes of lithium secondary batteries have the theoretical capacity limit of 372 mAh/g, which is a factor that hinders the increase of energy density. Silicon-based materials are an emerging solution to the problem. Silicon has theoretical capacity of 4010 mAh/g level, and the theoretical capacity of silicon is 10 times or more higher than that of carbon-based materials. However, charging/discharging efficiency of carbon-based materials is at 92% level while charging/discharging efficiency of silicon-based materials is at 80% level, and a change in volume is 300% or more during charging/discharging. When conduction paths are cut off in a continuous charging/discharging process, silicon-based materials do not work as the active material. To solve the problems with lower conductivity of silicon-based materials than carbon-based materials and poor electrical contact between particles due to large electrode swelling when silicon-based materials are used, linear shaped conductive materials such as carbon nanotubes (CNT) are additionally used, but it is still challenging to solve the electrode degradation problem due to non-uniform dispersion of silicon-based materials and linear shaped conductive materials. DISCLOSURE Technical Problem The present disclosure is directed to providing a negative electrode with improved conductivity through improved electrical contact, a method for manufacturing the negative electrode, and an electrochemical device including the negative electrode. Technical Solution To solve the above-described problems, according to an aspect of the present disclosure, there is provided a negative electrode of the following embodiment. According to a first embodiment, there is provided the negative electrode including a current collector; anda negative electrode active material layer located on at least one surface of the current collector and including granulated particles and a second binder, wherein the second binder holds and connects the granulated particles together,wherein the granulated particles include a negative electrode active material, a conductive material and a first binder, wherein the first binder connects and holds the negative electrode active material and the conductive material together. According to a second embodiment, in the first embodiment, the negative electrode active material may include a silicon-based active material alone, or a mixture of the silicon-based active material with a carbon-based active material. According to a third embodiment, in the second embodiment, the silicon-based active material