Battery Cell End Cover Venting With Controlled Weak-Point Fracture
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Solution Overview
Problem
Existing battery technologies face safety risks due to abnormal internal pressure rises during charging and discharging, leading to potential explosions and fires, and existing pressure relief mechanisms often have connection defects that compromise structural strength and lead to electrolyte leakage.
Innovation Solution
An end cover with a recessed depression forming a pressure relief mechanism and a weak portion that cracks when internal pressure reaches a threshold, eliminating connection defects and ensuring controlled pressure relief, thereby enhancing structural strength and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure relief mechanism is connected to the end cover after independent formation, then the pressure relief function is achieved, but connection defects occur that compromise structural strength and lead to electrolyte leakage
Solution Approach 1:
The pressure relief mechanism is integrated directly into the end cover as an integral structure, eliminating the need for separate connection between the pressure relief mechanism and end cover. This merging approach removes connection defects while maintaining the pressure relief function, thereby resolving the contradiction between reliability and structural strength.
2Reliability
If the depth of the weak portion is increased to ensure pressure relief, then the pressure relief effectiveness is improved, but the structural strength of the end cover is compromised
Solution Approach 1:
The weak portion is designed with non-uniform depth distribution, being deepest at the center and gradually shallower toward the edges. This local quality variation ensures that pressure relief occurs effectively at the critical center region while maintaining greater structural strength at the edges, thus resolving the contradiction between pressure relief effectiveness and overall structural strength.
3Ease of operation
If the weak portion is positioned on the perpendicular bisector to control cracking direction, then the valve opening direction is controlled, but the stress concentration on the end cover increases
Solution Approach 1:
The weak portion is pre-formed at the center of the end cover before pressure relief is needed. This preliminary action creates a predetermined stress concentration point that guides crack propagation in a controlled direction when pressure relief occurs, converting the potential harmful stress concentration into a useful feature for directional control.
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 effectively relieves internal pressure by cracking along the weak portion, increasing the valve opening area and ensuring the safety of the battery by controlling the valve opening direction, thus preventing explosions and fires while maintaining structural integrity.
Implementation Method 1
the pressure relief mechanism is configured for relieving internal pressure of the battery cell; where when the internal pressure of the battery cell reaches a threshold, the pressure relief mechanism cracks along the weak portion to relieve the internal pressure of the battery cell
Implementation Method 2
a depression, where the depression is formed by a surface of the end cover recessing in a thickness direction, and a bottom wall of the depression forms a pressure relief mechanism
Data Source
AI summary
Provided are an end cover, an end cover assembly, a battery cell, a battery, and an electric device. The end cover includes: two through holes, running through the end cover for mounting electrode terminals; a depression, where the depression is formed by a surface of the end cover recessing in a thickness direction, and a bottom wall of the depression forms a pressure relief mechanism; and a weak portion, disposed on the pressure relief mechanism, where the pressure relief mechanism is configured to crack along the weak portion when internal pressure of the battery cell reaches a threshold; where depth of the weak portion gradually decreases on one or two sides of a perpendicular bisector of a connecting line of the two through holes in a direction leaving the perpendicular bisector.