Battery Cell Vent Structure for Faster Pressure Relief
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Solution Overview
Problem
Existing battery cells have a low pressure relief rate during thermal runaway, leading to a risk of fire and explosion due to untimely pressure relief, resulting in low reliability.
Innovation Solution
A battery cell design with a first weak portion and a pressure relief region that cracks to open, allowing the region to flip around a second weak portion, increasing the pressure relief area and rate, thereby reducing the risk of fire and explosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single weak portion is provided on the wall portion for pressure relief, then the structure is simple, but the pressure relief rate is low and the opening effect is insufficient
Solution Approach 1:
The wall portion is divided into multiple functional segments: a first weak portion for initiating crack propagation to open the pressure relief region, and a second weak portion for enabling the pressure relief region to flip open. This segmentation allows each portion to perform its specific function optimally, improving the overall pressure relief rate while maintaining reasonable structural complexity.
Solution Approach 2:
The pressure relief region transitions from a two-dimensional sealed area to a three-dimensional flipped-open structure. By providing the second weak portion, the pressure relief region can rotate or flip along the second weak portion when pressure builds up, creating a dimensional change that significantly increases the effective pressure relief area and improves the pressure relief rate.
2Reliability
If the pressure relief region is made larger to increase pressure relief area, then the pressure relief rate improves, but the structural strength of the wall portion decreases
Solution Approach 1:
The wall portion is designed with non-uniform local properties: the first weak portion has reduced strength (through a score groove or reduced thickness) to facilitate crack initiation, while the second weak portion has controlled strength to enable flipping. The pressure relief region itself maintains sufficient strength during normal operation but can flip open when needed. This local differentiation allows a larger pressure relief area without compromising overall structural integrity.
Solution Approach 2:
The first and second weak portions are pre-formed in the wall portion during manufacturing (through scoring, grooving, or thickness reduction). These preliminary structural modifications prepare the wall portion for controlled failure modes: the first weak portion is pre-positioned to initiate cracking at specific locations, and the second weak portion is pre-positioned to serve as the hinge for flipping the pressure relief region, ensuring reliable operation when thermal runaway occurs.
3Reliability
If the wall portion thickness is reduced to improve pressure relief opening, then the pressure relief rate increases, but the overall structural strength and safety decrease
Solution Approach 1:
Instead of uniformly reducing the wall portion thickness, the design applies localized thickness reduction only at the first and second weak portions. The first weak portion has reduced thickness to facilitate crack initiation, and the second weak portion has controlled thickness to enable flipping. The rest of the wall portion and shell maintain their original sufficient thickness, preserving overall structural strength and safety while enabling effective pressure relief opening at the necessary locations.
Solution Approach 2:
The shell structure is segmented into different functional zones with different thickness characteristics: the main shell body maintains sufficient thickness for structural strength and safety, while the first and second weak portions have locally reduced thickness to enable the pressure relief mechanism. This segmentation allows the structure to simultaneously achieve both high strength and effective pressure relief opening.
Data Source
AI summary
A battery cell, a battery, and an electrical apparatus. The battery cell comprises a shell having a wall portion. The wall portion is provided with a first weak portion and a pressure relief region, the wall portion being configured to crack along the first weak portion to open the pressure relief region. The wall portion is further provided with a second weak portion, and the pressure relief region is configured to flip around the second weak portion when the first weak portion cracks, thereby relieving internal pressure of the battery cell. The second weak portion is disposed on the wall portion such that, when opened, the pressure relief region flips with the second weak portion as an axis. This structure allows the pressure relief region to be opened in a controlled manner to release gas when the internal pressure.