Pouch Battery Dual Sealing Structure for Lead-Side Leak Prevention
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Solution Overview
Problem
Existing secondary battery sealing technologies face challenges in achieving high sealing reliability and reducing tact time, particularly in pouch-type batteries, where insufficient sealing strength can lead to electrolyte leakage and venting issues.
Innovation Solution
The proposed solution involves a secondary battery design with a dual sealing system, comprising a first sealing portion and a second sealing portion, where the second sealing portion extends further in the opposite direction of the electrode lead's protruding direction. This design is accompanied by a sealing device featuring a main sealing block and a post sealing block, which apply pressure and heat to form a polymer ball within the battery case, enhancing sealing strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sealing portion is used in conventional battery sealing, then the manufacturing process is simple and fast, but the sealing reliability is insufficient leading to electrolyte leakage and venting issues
Solution Approach 1:
The sealing portion is divided into a first sealing portion and a second sealing portion that are positioned at different locations along the battery case perimeter. The first sealing portion seals the battery case body while the second sealing portion seals the electrode lead insertion area. This segmentation allows each sealing portion to be optimized for its specific function, thereby improving overall sealing reliability without requiring a completely complex new structure
Solution Approach 2:
A polymer ball is introduced as an intermediary material between the battery case and the electrode lead. This polymer ball fills the sealing portion and provides enhanced sealing by conforming to the irregular surfaces and distributing pressure uniformly. The polymer ball acts as a mediator that improves the sealing interface between rigid components, preventing electrolyte leakage at the electrode lead insertion point
2Strength
If conventional sealing methods are used, then the manufacturing process is fast with short tact time, but the sealing strength is insufficient to withstand internal gas pressure
Solution Approach 1:
The sealing process utilizes parameter changes by controlling the temperature and pressure conditions during sealing. The battery case and sealing portions are heated to a temperature range that allows the polymer ball to become sufficiently pliable for effective sealing, then cooled to solidify the seal. This controlled parameter change enables strong sealing bonds to form quickly, achieving high sealing strength without significantly extending the manufacturing cycle time
3Reliability
If the sealing portion is extended further to improve sealing coverage, then the sealing reliability improves, but the manufacturing complexity and time increase
Solution Approach 1:
Rather than extending a single sealing portion along the entire battery case, the sealing is segmented into two distinct portions: the first sealing portion for the battery case body and the second sealing portion for the electrode lead area. This segmentation provides comprehensive sealing coverage at critical locations without requiring excessive sealing length, thereby maintaining reasonable manufacturing time while improving reliability
Solution Approach 2:
The polymer ball in the second sealing portion performs self-service by automatically conforming to the electrode lead and battery case surfaces through its viscoelastic properties. When compressed during sealing, the polymer ball flows into gaps and irregularities, creating an effective seal without requiring precise alignment or extended sealing duration. This self-adjusting behavior reduces the time needed for effective sealing while maintaining high reliability
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 dual sealing system effectively prevents electrolyte leakage and withstands internal gas pressure, addressing venting issues while maintaining high sealing strength even with reduced tact time, thus enhancing the productivity and reliability of secondary battery manufacturing.
Implementation Method 1
a polymer ball is formed by the resin fused between the battery case and the lead film inside the second sealing portion
Data Source
AI summary
A secondary battery includes a battery case accommodating therein an electrode assembly with an electrode lead protruding therefrom and including a sealing portion in which an outer perimeter is sealed. The sealing portion includes a first sealing portion on the electrode lead side of the battery case; and a second sealing portion on the electrode lead side of the battery case. The first sealing portion and the second sealing portion each have one end and another end in a protruding direction of the electrode lead, and the another end of the second sealing portion extends further in a direction opposite to the protruding direction of the electrode lead than the another end of the first sealing portion