Wet Electrode Cell Pressing Before Charging to Prevent Cracking
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Solution Overview
Problem
The existing methods for manufacturing secondary batteries, such as those for electric vehicles, often result in electrode cracking during the drying process, leading to reduced battery performance due to increased internal resistance caused by deformation and creases in the unit cells during initial charging.
Innovation Solution
A battery manufacturing method that involves forming unit cells with electrodes containing an electrolytic solution, followed by a surface pressing step to flatten the electrodes and adjust their thickness before initial charging, thereby reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the electrode active material slurry is dried to form a dry electrode, then the electrode structure is stabilized, but cracking occurs in the electrode
Solution Approach 1:
The patent changes the physical state parameter of the electrode from dry to wet by maintaining the electrode active material slurry in a non-dried state containing electrolytic solution. This parameter change eliminates the cracking issue that occurs during drying while still allowing the electrode to function properly in the wet state within the unit cell structure.
2Ease of manufacture
If the unit cell is charged in a deformed state with creases, then the charging process is simplified, but excessive deformation occurs due to unbalanced gas generation and volume changes
Solution Approach 1:
The patent applies preliminary action by performing surface pressing on the unit cell before the initial charging step. This pre-compression flattens creases and prevents excessive deformation during charging by establishing proper contact between electrodes and current collectors in advance, ensuring reliable electrical connections throughout the charging process.
3Manufacturing precision
If the electrode is pressed before initial charging, then internal resistance is reduced, but the electrode deformation control becomes more complex
Solution Approach 1:
The patent extracts the surface pressing operation from the electrode manufacturing process and applies it directly to the assembled unit cell. This separation allows simple compression of the entire unit cell structure rather than complex control of individual electrode deformation, reducing process complexity while achieving the desired reduction in internal resistance through improved contact.
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 method effectively prevents electrode cracking and deformation, resulting in lower internal resistance and improved battery performance by ensuring uniformity and stability of the unit cells during charging.
Implementation Method 1
a pressing surface of a pressing part is brought into surface contact with one unit cell or with two or more stacked unit cells from the stacking direction and pressure is applied
Data Source
AI summary
A battery manufacturing method includes forming a unit cell having a positive electrode that is obtained by a positive electrode active material layer containing an electrolytic solution being disposed on a positive electrode current collector, a negative electrode that is obtained by a negative electrode active material layer containing an electrolytic solution being disposed on a negative electrode current collector, and a separator interposed between the positive electrode and the negative electrode. The battery manufacturing method further includes applying pressure to one unit cell or with two or more stacked unit cells from the stacking direction, and charging the one unit cell or the two or more stacked unit cells after applying of the pressure. The method is performed such that the positive electrode and the negative electrode are formed without an application film being subjected to a drying process performed through heating.