US-12624894-B2 - Electrode drying system and electrode drying method

US12624894B2US 12624894 B2US12624894 B2US 12624894B2US-12624894-B2

Abstract

A system for drying an electrode includes: an oven which applies hot air and radiant heat to an electrode sheet; and a controller which receives information on drying standby time, and controls an amount of heat supplied into the oven. Herein, the controller controls to supply a reduced amount of heat to the oven during an initial drying time right after the supply of the electrode sheet after the drying standby time.

Inventors

Jin Young Son
Eun Hoe Jeong
Sang Hoon Choy
Shin Wook JEON
Young Kuk Ko

Assignees

LG ENERGY SOLUTION, LTD.

Dates

Publication Date: 20260512
Application Date: 20211125
Priority Date: 20201127

Claims (15)

1 . A system for drying an electrode, the system comprising: an oven which applies hot air and radiant heat to an electrode sheet; and a controller which receives information on drying standby time when a supply of the electrode sheet into the oven is stopped, wherein the controller determines and controls an amount of heat supplied into the oven according to a length of the drying standby time, and wherein the controller controls to supply a reduced amount of heat than a general supply amount of heat (Q t ) to the oven during an initial drying time right after the supply of the electrode sheet after the drying standby time.
2 . The system of claim 1 , wherein the controller controls to supply the general supply amount of heat (Q t ) into the oven after the initial drying time passes.
3 . The system of claim 1 , wherein the initial drying time (T) is time-sequentially divided into n time sections, and when each amount of heat, which is supplied into the oven at T 1 , T 2 , T 3 . . . . T n , is defined as Q1, Q 2 , Q 3 . . . . Q n , the controller controls the amount of heat supplied into the oven to satisfy a following relation: Q 1 <Q 2 <Q 3 < . . . <Q n <Q t , and wherein the n is equal to or greater than 2.
4 . The system of claim 3 , wherein the controller controls to reduce a ratio (Q 1 /Q t ) of the amount of heat (Q 1 ) supplied to the initial time section (T 1 ) to the general supply amount of heat (Q t ) as the drying standby time increases.
5 . The system of claim 1 , wherein the oven includes at least one hot air nozzle, which applies convective heat by supplying hot air to the electrode sheet, and at least one heater, which applies radiant heat to the electrode sheet.
6 . The system of claim 5 , wherein the controller controls the amount of heat supplied into the oven in a manner that increases or decreases at least one of conditions including a temperature of hot air sprayed from the hot air nozzle, a speed of the hot air, or an output of the heater.
7 . The system of claim 1 , wherein the controller uniformly controls the amount of heat supplied into the oven.
8 . The system of claim 1 , further comprising an electrode sheet sensor which senses that the electrode sheet is not supplied into the oven and transmits information on the drying standby time to the controller.
9 . The system of claim 1 , further comprising a measuring unit which collects information on a dried amount of the electrode sheet and transmits the information collected on the dried amount of the electrode sheet to the controller, wherein the controller determines a dried level of the electrode sheet according to the information on the dried amount received from the measuring unit and changes the amount of heat supplied into the oven in real time.
10 . The system of claim 9 , wherein the measuring unit collects information on at least one of a solid content or a surface temperature of the electrode sheet before and after passing through the oven.
11 . The system of claim 10 , wherein the measuring unit includes at least one of a web gauge or a temperature measuring instrument.
12 . A method of drying an electrode sheet, the method comprising: (a) a process of collecting information on drying standby time which is a time interval when a supply of the electrode sheet into an oven for drying the electrode sheet is stopped; (b) a process of determining a condition on an amount of heat to be supplied into the oven when the electrode sheet is supplied into the oven after the drying standby time; and (c) a process of supplying the electrode sheet into the oven after the drying standby time and drying the electrode sheet at the condition on the amount of heat determined during the process (b), wherein the process (b) includes determining the condition on the amount of heat to supply a reduced amount of heat than a general supply amount of heat (Q t ) to the oven during an initial drying time.
13 . The method of claim 12 , wherein the process (b) includes determining the condition on the amount of heat to supply the general supply amount of heat (Q t ) into the oven after the initial drying time passes.
14 . The method of claim 13 , wherein during the process (b), the initial drying time (T) is time-sequentially divided into n time sections, and when each amount of heat, which is supplied into the oven at T 1 , T 2 , T 3 . . . . T n , is defined as Q 1 , Q 2 , Q 3 . . . . Q n , the amount of heat supplied into the oven is determined to satisfy a following relation: Q 1 <Q 2 <Q 3 < . . . <Q n ≤Q t , and wherein the n is equal to or greater than 2.
15 . The method of claim 14 , wherein during the process (b), the condition of the amount of heat is determined so that a ratio (Q 1 /Q t ) of the amount of heat (Q 1 ) supplied to an initial time section (T 1 ) to the general supply amount of heat (Q t ) is reduced as the drying standby time increases.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/017448, filed on Nov. 25, 2021, which claims the benefit of priority based on Korean Patent Application No. 10-2020-0162423 filed on Nov. 27, 2020 and Korean Patent Application No. 10-2021-0162711 filed on Nov. 23, 2021, the disclosures of which are incorporated herein by reference. FIELD OF INVENTION The present invention relates to an electrode drying system and electrode drying method, and more particularly, to an electrode drying system and electrode drying method for suppress over-drying at the initial drying of an electrode sheet which is supplied into an oven right after drying standby time in the case that there is drying standby time when the electrode sheet is not supplied into the oven. BACKGROUND Recently, secondary batteries capable of charging and discharging have been widely used as energy sources of wireless mobile devices. In addition, the secondary battery has attracted attention as an energy source for electric vehicles, hybrid electric vehicles, etc., which are proposed as a solution for air pollution released from existing gasoline vehicles and diesel vehicles using fossil fuel. Therefore, due to such advantages, there are diverse applications using the secondary battery, and it is expected that the secondary battery will be applied to many other fields and products in the future. Such secondary batteries may be classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc., depending on the composition of the electrode and the electrolyte. There is an increased demand for lithium-ion polymer batteries which are less likely to leak electrolyte and which are easy to manufacture. In general, secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is embedded in a cylindrical or rectangular metal can, depending on the shape of a battery case, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. The electrode assembly built into the battery case is composed of a positive electrode, a negative electrode, and a separator interposed between the positive and the negative electrodes. The electrode assembly is a power generating element, capable of charging and discharging. The electrode assembly is classified into a jelly-roll type wound, where the electrodes are long sheet-shaped and are coated with active materials with a separator interposed between the positive electrode and the negative electrode, and a stack type in which a plurality of positive electrodes and negative electrodes of a predetermined size are sequentially stacked while a separator is interposed therebetween. The positive electrode and the negative electrode are formed by applying a positive electrode slurry containing a positive electrode active material and a negative electrode slurry containing a negative electrode active material to a positive electrode current collector and a negative electrode current collector, respectively, to thereby form a positive electrode active material layer and a negative electrode active material layer, respectively, followed by drying and rolling them. At this time, the drying condition of the electrode influences the quality and physical properties of the electrode. Particularly, the adhesive force and the coupled level of the surface of the electrode can be significantly changed by controlling the deviation of the dryness for the width direction of the electrode and the time point when the drying is completed during the drying. Further, the electrode sheet, on which an electrode slurry has been coated, goes through a drying process while moving through a drying section as a consecutive process, but there may be a time interval between an electrode slurry coating process and a drying process, and the surplus amount of heat is accumulated inside the oven during the drying standby time when the electrode sheet is not supplied into the drying section. In the case that an electrode sheet is supplied into the oven in a state that such a surplus amount of heat has been accumulated, a crack or a wrinkle may be generated on the electrode during the initial drying section due to the excessive amount of heat accumulated in the oven. Particularly, a crack on the electrode due to over-drying in the initial drying section allows electrode powder to be generated, and the electrode powder is scattered along the convection of hot air in the oven, thereby contaminating the surrounding electrode and deteriorating the quality of the electrode. Hence, it is very important to prevent over-drying in the initial drying section of the electrode. Therefore, there is a need for an electrode drying technology for preventing over-drying during the initial drying section. DISCLOSURE The present invention is