Secondary Battery Venting Unit Geometry for Directed Gas Release
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Solution Overview
Problem
Existing secondary battery designs face challenges in reliably venting gases at specific pressure ranges to prevent explosions, with conventional vent structures often lacking in design freedom and reliability.
Innovation Solution
A venting unit with a base and notch portions designed to fracture at a predetermined pressure range, featuring specific geometric configurations and stress distribution to control gas emission direction, is integrated into the secondary battery cell case, allowing for high-reliability gas emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional vent structure is used, then the battery can vent gas, but the fracture pressure is not controllable and reliability is low
Solution Approach 1:
The patent applies parameter changes by precisely controlling the geometric parameters of the notch portion (length, width, depth, position) to achieve controllable fracture pressure. By varying these parameters, the stress distribution and fracture characteristics are modified to ensure reliable venting at specific pressure thresholds, directly resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The notch portion is pre-formed in the case with specific dimensions before the battery operates. This preliminary action creates a predetermined weak point that will fracture at a specific pressure, eliminating the need for complex real-time control mechanisms and ensuring reliable venting without increasing device complexity.
2Ease of manufacture
If the vent structure is simplified, then manufacturing is easier, but design freedom and control over gas emission direction are reduced
Solution Approach 1:
The patent employs asymmetry by designing the notch portion with non-uniform geometry (varying width, depth, and angle along its length) and positioning it asymmetrically on the case. This asymmetric design enables control over gas emission direction while maintaining a relatively simple manufacturing process, as the asymmetric features can be created through standard molding or machining operations.
Solution Approach 2:
The notch portion is designed with local quality variations, where different sections of the notch have different dimensions and orientations. This allows specific regions to control gas flow in particular directions, providing adaptability for different venting requirements without requiring a completely complex multi-component structure.
3Reliability
If the notch portion geometry is optimized for specific fracture pressure, then venting reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The optimal notch geometry is predetermined through design calculations and simulations, allowing manufacturers to use standard tolerances rather than requiring ultra-precise manufacturing. The preliminary design phase identifies geometric parameters that are robust to normal manufacturing variations, ensuring reliable fracture pressure control without excessively tight tolerance requirements.
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 controls gas emission direction and ensures reliable fracture at a specific pressure range, enhancing design freedom and safety by improving the venting mechanism within the secondary battery cell.
Implementation Method 1
the first notch portion and the second notch portion may extend in a direction crossing both longitudinal and width directions of the case, and a center of the first notch portion and a center of the second notch portion may intersect each other
Implementation Method 2
the venting unit may be configured to be fractured when internal pressure (P) of the case satisfies the following conditional equation: 0.45[MPa]≤P≤0.55[MPa]
Data Source
AI summary
A secondary battery cell includes: a case in which an electrode assembly is accommodated; a cap plate assembly coupled to at least one side of the case; and a venting unit including a base coupled to one surface of the case and a notch portion formed on the base, and the notch portion includes: a first notch portion extending in a first direction; a second notch portion extending in a second direction intersecting the first direction; and a third notch portion extending in a third direction, parallel to a longitudinal direction of the base from both ends of the first notch portion and the second notch portion.