Secondary Battery Electrode Active Material Layer Thickness Control
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Solution Overview
Problem
Existing methods for forming active material layers in secondary batteries, such as continuous and intermittent application techniques, face challenges like line defects, uneven thickness, and air bubbles, which affect the reliability and performance of the electrodes, particularly due to issues with slurry flow and coating valve operations.
Innovation Solution
A production method and apparatus that adjust the interval between the die head and current collector, and the opening of the coating valve, to precisely control the thickness of the active material layer, forming a thick-layer portion and a thin-layer portion with a smaller insulating member, ensuring stable slurry application and reducing the formation of protrusions and air bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating member is disposed on the electrode to prevent short circuit, then safety is improved, but the thickness of the battery element increases at that position, decreasing energy density per unit volume
Solution Approach 1:
The patent applies local quality by creating a thin-layer portion of the active material layer at the position where the insulating member is disposed. This localized thinning compensates for the thickness increase caused by the insulating member, maintaining uniform overall thickness. The thin-layer portion has smaller thickness than other portions of the active material layer, which prevents the battery element thickness from increasing at the insulating member position, thereby preserving energy density while maintaining safety.
2Reliability
If an insulating member is disposed on the electrode to prevent short circuit, then safety is improved, but uniform pressure cannot be applied to the battery element, decreasing quality stability
Solution Approach 1:
The patent creates a thin-layer portion of the active material layer at the position where the insulating member is disposed. This localized thinning ensures that the overall thickness of the battery element remains uniform even with the insulating member present. As a result, uniform pressure can be applied across the entire battery element during assembly, preventing deformation and ensuring stable quality and electric characteristics.
3Quantity of substance
If the active material layer thickness is reduced at the insulating member position, then energy density is improved, but the active material layer may become too thin, affecting electrode performance
Solution Approach 1:
The patent creates a thin-layer portion of the active material layer at the position where the insulating member is disposed, while maintaining a normal thickness in other portions. This localized thinning approach reduces the overall thickness of the battery element at the insulating member position, preserving energy density, while ensuring that the active material layer maintains sufficient thickness in other areas to guarantee electrode performance and functionality.
Data Source
Figure 1~3
Figure 4~5
Figure 6a1~6b2
AI summary
An electrode for a secondary battery including an electrode laminated assembly that has a configuration in which electrodes and a separator are laminated, includes current collector 3 and active material layer 2 formed on a surface of current collector 3. Active material layer 2 includes a thick-layer portion and a thin-layer portion that is positioned at an edge portion of the active material layer and that is smaller in thickness than the thick-layer portion, and is formed by discharging slurry containing an active material from discharge port 12a of die head 12 toward the surface of current collector 3, the slurry being supplied to die head 12 through coating valve 13. At the time of the formation of the thin-layer portion of active material layer 2, the slurry supplied through coating valve 13 having a smaller opening amount than at the time of the formation of the thick-layer portion is discharged toward current collector 3 from discharge port 12a that is closer to current collector 3 than at the time of the formation of the thick-layer portion.