Battery Cell Shell Weak-Point Layout for Reliable Pressure Relief
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Solution Overview
Problem
Pressure relief mechanisms in batteries often fail prematurely, leading to a loss of normal pressure relief function.
Innovation Solution
A battery cell design with a weak portion on the shell that is configured to be destroyed when internal pressure is released, where the maximum distance between the weak portion projection and the center point is less than or equal to 0.4 times the minimum radial dimension of the shell, allowing for a thicker and more robust weak portion to resist external impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the weak portion is made thinner to facilitate easier manufacturing, then the manufacturing precision requirement increases, but the ability to resist external impact decreases
Solution Approach 1:
The patent applies local quality by positioning the weak portion in a specific region of the shell wall where the local mechanical properties differ from other areas. The weak portion is located in a region that experiences smaller deformation during pressure release, allowing it to maintain sufficient thickness for impact resistance while still enabling controlled failure for pressure relief. This spatial differentiation of structural properties resolves the contradiction between manufacturability and impact resistance.
2Reliability
If the weak portion is arranged in a region with larger deformation during pressure release, then the fracture initiation pressure is reduced, but the weak portion is more likely to be damaged prematurely
Solution Approach 1:
The patent applies preliminary action by pre-positioning the weak portion in a carefully selected region of the shell wall before the battery undergoes pressure cycles. The weak portion is placed in an area that experiences controlled, smaller deformation during normal pressure release, which prevents premature damage while ensuring that the weak portion will eventually fail at the appropriate fracture initiation pressure. This advance positioning strategy resolves the contradiction between reliability and premature damage risk.
3Strength
If the weak portion is made thicker to resist external impact, then the ability to resist external impact increases, but the manufacturing precision requirement increases
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness and dimensional parameters of the weak portion based on its specific location in the shell wall. Rather than using a uniform thickness throughout, the weak portion's dimensions are tailored to the local stress and deformation characteristics of its position. This parameter optimization allows the weak portion to achieve sufficient impact resistance while maintaining manufacturability with reasonable precision requirements.
Data Source
AI summary
The battery cell includes a shell, the shell has a wall portion, the wall portion includes a weak portion, and the weak portion is configured to be destroyed when the battery cell releases internal pressure. An outer surface of the wall portion has a center point. A maximum distance between a projection of the weak portion on the outer surface of the wall portion and the center point is a, the minimum radial dimension of the outer surface of the wall portion is A, and a and A satisfy: a≤0.4A. By setting a≤0.4A, the weak portion is arranged at a region, with a relatively low stiffness, of the wall portion. When the battery cell releases the internal pressure, the region undergoes a large deformation under the action of gas, and therefore the weak portion arranged at the region is easily damaged.