Pouch Cell PTFE Venting Structure for Internal Gas Pressure Relief
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Solution Overview
Problem
Pouch-shaped lithium secondary batteries face safety risks due to increased pressure from gas generation during activation, charging, and discharging, which can lead to explosion, and existing solutions do not effectively address gas discharge without increasing the battery case size.
Innovation Solution
A pouch-shaped battery cell with a venting portion made of stacked polytetrafluoroethylene (PTFE) layers, where the first layer has pores and the second layer does not, attached to the inside of the battery case, allowing gas to be discharged when pressure exceeds a threshold while preventing foreign matter entry and maintaining reversibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a venting portion is attached to the battery case to discharge gas, then safety is improved, but the external size of the battery case increases
Solution Approach 1:
The venting portion is nested inside the battery case by attaching it to the inner surface of the battery case. The venting portion includes a first layer with pores and a second layer without pores, creating a nested structure where the venting mechanism is contained within the existing battery case volume, thus providing gas discharge functionality without increasing external dimensions
Solution Approach 2:
The first layer of the venting portion is made with a porous structure that allows gas to pass through when pressure increases, while the second layer provides a non-porous barrier. This porous material configuration enables gas discharge functionality within the constrained space of the battery case, maintaining safety without requiring additional external volume
2Stress or pressure
If a venting portion is attached to discharge gas, then pressure control is improved, but the battery case structure becomes more complex
Solution Approach 1:
The venting portion is segmented into two distinct layers: a first layer with pores for gas discharge and a second layer without pores for sealing and structural support. This segmentation allows each layer to perform its specific function independently, achieving effective pressure control while keeping the overall structure relatively simple and manufacturable
Solution Approach 2:
The venting portion uses a composite structure combining porous and non-porous materials in two layers. This composite configuration enables the venting portion to simultaneously achieve gas discharge functionality and structural integrity, improving pressure control without significantly complicating the battery case structure
3Object-generated harmful factors
If a venting portion is attached to discharge gas, then gas discharge functionality is improved, but foreign matter entry risk increases
Solution Approach 1:
The venting portion utilizes a porous first layer that selectively allows gas molecules to pass through while the non-porous second layer acts as a barrier to larger foreign matter particles. This porous material configuration enables the venting portion to discharge harmful gas pressure while simultaneously filtering out external contaminants, thus improving gas discharge functionality without significantly increasing foreign matter entry risk
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 solution enables safe and continuous use of the battery by allowing gas discharge without increasing the battery case size, maintaining pressure within safe limits, and preventing external moisture entry, while being reversible to prevent gas discharge when pressure equals atmospheric pressure.
Implementation Method 1
configured to have a first layer with pores formed therein and a second layer with no pores formed therein stacked, wherein the gas in the pouch-shaped battery case passes through the porous film when a predetermined pressure is exceeded
Implementation Method 2
the valve member is made of porous film, such as PTFE, and the porous film is fixed by a support member at the lower side of a vent hole formed in a housing cover
Data Source
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AI summary
The present invention relates to a pouch-shaped battery cell including a pouch-shaped battery case made of a laminate sheet, an electrode assembly received in the pouch-shaped battery case, and a venting portion configured to discharge gas in the pouch-shaped battery case, wherein the pouch-shaped battery case is provided with an opening, and the opening is opened or closed by the venting portion attached to the inside of the opening, and wherein the venting portion is opened to rapidly discharge gas when pressure in the pouch-shaped battery cell increases and reversibly blocks the inside and the outside of the battery cell, and a method of manufacturing the same.