Battery Cell Pressure Relief Venting Against Premature Opening
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Solution Overview
Problem
The pressure relief structure in battery cells often opens prematurely when the battery is impacted, leading to a failure in the normal pressure relief function.
Innovation Solution
A pressure relief device with a pressure relief portion, a weak portion, and a weld mark portion is designed. The weld mark portion is arranged on the pressure relief portion and is formed by ablating at a high temperature, which anneals the weak portion, allowing it to be thicker and more resistant to external impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the weak portion is made thinner to facilitate easier machining, then machining difficulty is reduced, but the resistance to external impact decreases causing premature opening
Solution Approach 1:
The weld mark portion is formed in advance through laser welding before the pressure relief device is put into service. This preliminary high-temperature treatment anneals the weak portion, refining its grain structure and eliminating internal stresses, thereby enhancing its toughness and impact resistance without requiring post-processing machining
Solution Approach 2:
The traditional mechanical machining process is replaced by laser welding technology. Instead of using mechanical tools to thin the weak portion, a laser beam is used to locally melt and fuse material, forming a weld mark portion that simultaneously serves as a heat treatment zone to improve the mechanical properties of the weak portion
2Strength
If the weak portion is made thicker to improve impact resistance, then premature opening is prevented, but machining difficulty and production cost increase
Solution Approach 1:
The thickness of the weak portion is optimized within a specific range (0.5-3mm) to balance impact resistance and manufacturability. The laser welding process parameters (power, speed, focal position) are precisely controlled to achieve the desired weld mark portion geometry and heat treatment effect without excessive material removal or complex machining
3Reliability
If the weld mark portion is formed too close to the weak portion, then annealing effect is enhanced, but the weak portion may be damaged during formation
Solution Approach 1:
The weld mark portion is positioned at a specific distance (0.5-10mm) from the weak portion, creating a localized heat treatment zone. This spatial arrangement ensures that the high temperature from laser welding effectively anneals the weak portion while the controlled distance prevents direct thermal damage or melting of the weak portion structure
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 increased thickness of the weak portion improves resistance to external impacts, reducing the risk of premature opening and enhancing the pressure relief function, while also simplifying machining and reducing production costs.
Implementation Method 1
the weld mark portion is arranged on the pressure relief portion and is configured to anneal the weak portion when the weld mark portion is formed
Implementation Method 2
It is needed to ablate the weld mark portion at a high temperature during formation
Data Source
AI summary
A pressure relief device includes a pressure relief portion, a weak portion and a weld mark portion. The weak portion is arranged at the pressure relief portion and configured to crack when pressure is relieved from the battery cell. The weld mark portion is arranged at the pressure relief portion and configured to anneal the weak portion when the weld mark portion is formed. The weld mark portion is arranged on the pressure relief portion of the pressure relief device.