Secondary Battery Electrode Heating for Uncoated Portion Strength Control
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Solution Overview
Problem
Existing secondary battery manufacturing processes face issues of electrode breakage during rolling due to elongation differences between coated and uncoated portions, and sticking during assembly due to uncoated portion heating, which existing heating methods fail to address simultaneously.
Innovation Solution
A method for manufacturing a secondary battery electrode involves forming an uncoated portion on the current collector, heating only a specific region (region A) of the uncoated portion to a controlled temperature (190° C. to 230° C.) using a ceramic heater, and then rolling the electrode mixture layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the uncoated portion is heated to reduce tensile strength and prevent electrode breakage, then electrode breakage is suppressed, but sticking occurs during assembly process
Solution Approach 1:
The patent applies local quality by heating only a specific region (region A) of the uncoated portion rather than the entire uncoated portion. This localized heating reduces tensile strength only where needed to prevent breakage during rolling, while leaving other areas with sufficient tensile strength to prevent sticking during assembly. The heating unit is positioned to contact only region A, creating a spatially differentiated treatment that resolves the contradiction between preventing breakage and preventing sticking.
2Reliability
If the entire uncoated portion is heated, then electrode breakage is prevented, but sticking occurs during welding in assembly process
Solution Approach 1:
The patent implements local quality by restricting heating to region A (from the end of the uncoated portion to a 1/2 to 1/3 point in the direction of the electrode mixture layer) rather than heating the entire uncoated portion. This creates a gradient where only the critical region near the boundary has reduced tensile strength to prevent breakage, while the rest of the uncoated portion maintains sufficient strength for assembly operations without sticking.
3Manufacturing precision
If heating is applied to reduce deformation of uncoated portion, then elongation difference is reduced, but tensile strength becomes too low causing sticking
Solution Approach 1:
The patent applies local quality by heating only region A of the uncoated portion, creating a spatially differentiated tensile strength distribution. In region A, tensile strength is reduced to match the mixture layer and prevent deformation and breakage. In region B (the rest of the uncoated portion), tensile strength is maintained at higher levels (18-28 kgf/mm²) to prevent sticking during assembly. This localized approach allows different regions to have different mechanical properties optimized for their specific functions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces electrode breakage during rolling and prevents sticking during assembly by maintaining appropriate tensile strength in the uncoated portion, thereby improving process yield and operating efficiency.
Implementation Method 1
heating region A, a portion of the uncoated portion set in the direction from an end of the uncoated portion to the electrode mixture layer
Implementation Method 2
heating unit, such as induction heating annealing (IHA; high-frequency induction heating device), is installed in front of a main roll unit of rolling equipment to heat the uncoated portion before the rolling process
Implementation Method 3
The heating may be performed by contacting region A with the heating unit. The heating unit may have a contact portion formed of a ceramic material
Data Source
AI summary
The electrode for a secondary battery includes an electrode current collector and an electrode mixture layer formed on at least one surface of the electrode current collector so that a portion of the electrode current collector is exposed to form an uncoated portion, wherein a retention rate of tensile strength of the uncoated portion, according to Equation 1 below, is 0.75 or greater,RTS=TSNC/TSML[Equation 1]where RTS is a retention rate of tensile strength of the uncoated portion, TSNC is the tensile strength of the uncoated portion in a region excluding region A, a portion of the uncoated portion set in the direction of the electrode mixture layer from the end of the uncoated portion, and TSML is the tensile strength of the electrode current collector having the electrode mixture layer formed on at least one surface thereof.