Folded Pouch Cell Pressing to Prevent Lithium Precipitation
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Solution Overview
Problem
Lithium precipitation at the upper end of lithium pouch-type batteries during rapid charging leads to cell deterioration and swelling, due to stagnated electrolyte and weak lamination, which affects charging capacity and lifespan.
Innovation Solution
A method for manufacturing secondary batteries involves forming folded cells with unit cells and a separation film, attaching a pressing tape to the end of the folded cell, and pressing the battery case to apply force, preventing electrolyte stagnation and precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid charging rate is increased to satisfy fast charging demand, then charging speed is improved, but lithium precipitation occurs at the upper end of the cell causing deterioration in retention and swelling
Solution Approach 1:
The pressing tape is attached to the upper end of the folded cell before charging to pre-establish the pressing force that will prevent lithium precipitation during rapid charging. This preliminary action ensures that when fast charging occurs, the pressing force is already in place to push electrolyte toward the upper end and prevent precipitation.
Solution Approach 2:
The pressing tape applies a counteracting force to the harmful effect of lithium precipitation. By pressing the upper end of the folded cell, it creates an opposing force that prevents lithium from precipitating at the upper end during rapid charging, thereby counteracting the harmful effect before it can occur.
2Reliability
If pressing force is applied to the folded cell to prevent lithium precipitation, then cell lifespan is improved, but additional components and process complexity are introduced
Solution Approach 1:
The pressing tape is a simple, inexpensive component that is attached to the folded cell and remains in place during charging. It is a disposable element that serves its function of preventing lithium precipitation and can be easily integrated into the manufacturing process without requiring complex or expensive equipment.
Solution Approach 2:
The pressing tape acts as an intermediary component between the folded cell and the pressing mechanism. It transfers the pressing force uniformly to the upper end of the folded cell and can be easily attached and removed, simplifying the overall system while achieving the desired effect of preventing lithium precipitation.
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 prevents lithium precipitation and abnormal swelling, maintaining long-term charging capacity by ensuring the electrolyte is pushed out, thus extending the battery's lifespan.
Implementation Method 1
a pressing process of pressing an outer surface of the battery case to press the folded cell
Data Source
AI summary
The present invention relates to a method for manufacturing a secondary battery. The method for manufacturing the secondary battery comprises: positioning a plurality of unit cells, each unit cell comprising at least one electrode and at least one separator, wherein the plurality of unit cells are positioned on a surface of a separation film to sequentially fold the unit cells and form a folded cell; attaching a pressing tape to an end of the folded cell; accommodating the folded cell and an electrolyte in a battery case; and pressing an outer surface of the battery case to press the folded cell.