Electrode Assembly Pressing for Non-Bonded Battery Interfaces
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Solution Overview
Problem
The non-uniform application of electrode slurry in secondary battery manufacturing leads to non-bonded areas between electrodes and separators, resulting in increased interfacial resistance and lithium precipitation, which deteriorates the performance of lithium-ion batteries.
Innovation Solution
A method involving the manufacturing of secondary batteries that includes a unit cell process, an electrode assembly process where unit cells and separator sheets are alternately stacked, a correction process to address height differences using a correction sheet, and a pressing process with a stepped pressing surface to bond non-bonded areas, ensuring uniformity and improved bonding between electrodes and separators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrode slurry is applied to conductive foils, then electrodes are manufactured, but non-uniform coating thickness forms non-bonded areas between electrodes and separator
Solution Approach 1:
The patent applies preliminary pressing action during the electrode assembly manufacturing process to compensate for non-uniform coating thickness before the battery is sealed. By pressing the stacked unit cells and separator sheets, the electrodes are forced into intimate contact with the separator, eliminating non-bonded areas that would otherwise cause lithium precipitation and increased interfacial resistance.
2Productivity
If unit cells are stacked with separator sheets, then electrode assembly is manufactured, but height differences create non-bonded areas on the outer surface
Solution Approach 1:
The patent introduces a correction sheet with locally varying thickness to compensate for height differences at specific locations on the electrode assembly. The correction sheet is designed with different thickness regions corresponding to different height deviations, allowing precise local compensation without requiring complete disassembly or re-manufacturing of the entire electrode assembly.
Solution Approach 2:
The correction sheet is applied before the final pressing process, performing a preliminary correction of surface irregularities. This preliminary action prepares the electrode assembly for uniform pressing, ensuring that all areas make contact with the pressing surface and achieve proper bonding.
3Reliability
If non-bonded areas exist between electrode and separator, then interfacial resistance increases, but lithium precipitation occurs on negative electrode
Solution Approach 1:
The pressing process is performed as a preliminary action before battery assembly to eliminate non-bonded areas and prevent lithium precipitation. By applying pressure while the electrode assembly is still accessible, the electrodes are forced into complete contact with the separator, preventing the formation of non-bonded areas that would later cause lithium plating and increased resistance during battery operation.
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
The method effectively corrects height differences and bonds non-bonded areas, thereby enhancing the performance of secondary batteries by reducing lithium precipitation and improving interfacial resistance.
Implementation Method 1
a pressing process of pressing the electrode assembly
Implementation Method 2
pressing the electrode assembly, wherein the non-bonded area of the electrode and the separator inside the unit cell and the non-bonded area of the unit cell and the separator sheet inside the electrode assembly are pressed to bond the non-boned areas to each other
Data Source
AI summary
The present disclosure provides a method and apparatus for manufacturing a secondary battery. The method includes a manufacturing a unit cell including an electrode and a separator; folding a plurality of unit cells and a separator sheet to be alternately stacked so as to manufacture an electrode assembly; correcting a height difference formed on an outer surface of the electrode assembly; and pressing the electrode assembly, wherein, in the correction step, a correction sheet is disposed on an area formed with a relatively low height with respect to the inside of the electrode assembly to correct the height difference formed on the outer surface of the electrode assembly.