Rectangular Battery Diaphragm Convex Shape Current Interruption
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries face challenges in reliably interrupting the current path due to the difficulty in deforming a circular flat diaphragm in a limited space, leading to potential rupture under vibration or impact, which compromises the strength of the fragile portion and the effectiveness of the current interrupting mechanism.
Innovation Solution
A rectangular secondary battery design featuring a diaphragm formed into a convex shape protruding inside the battery container and elongated in the longitudinal direction, increasing its strength and surface area, allowing for stable mechanical interruption of the current path when internal pressure reaches a predetermined value, thus enhancing vibration and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a circular flat diaphragm is used in the current interrupting mechanism, then the structure is simple, but the diaphragm is difficult to deform in limited space and may rupture under vibration or impact
Solution Approach 1:
The diaphragm is changed from a flat circular shape to a convex shape protruding into the battery container. This curvature provides structural strength to resist vibration and impact, while the protruding form allows sufficient deformation space when internal pressure increases, enabling reliable current interruption without premature rupture.
2Strength
If the diaphragm is made stronger to resist vibration and impact, then vibration and impact resistance improve, but the difficulty to deform the diaphragm increases
Solution Approach 1:
The diaphragm is designed to protrude into the battery container in the vertical dimension, creating a three-dimensional convex structure. This additional spatial dimension provides both structural strength against lateral forces (vibration and impact) and sufficient deformation pathway in the vertical direction when internal pressure increases, resolving the contradiction between strength and deformability.
3Area of stationary object
If the diaphragm surface area is increased to improve pressure response, then the current interrupting effectiveness improves, but the space required for deformation increases
Solution Approach 1:
The convex curved shape of the diaphragm allows a larger surface area to be packed into a compact volume within the battery container. The curvature distributes stress evenly across the surface while maintaining structural integrity, enabling large surface area for pressure response without requiring excessive deformation space.
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 modified diaphragm design significantly increases the battery's vibration and impact resistance, ensuring reliable and stable interruption of the current path even under increased internal pressure, preventing damage from external factors like vibration or impact.
Implementation Method 1
when the internal pressure of the battery container reaches a predetermined value to deform the top portion of the diaphragm into a concave shape
Data Source
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AI summary
A rectangular secondary battery (1) includes a current interrupting portion (60) disposed in a current path between a collector plate (21) connected to a rolled electrode group (40) and an external terminal (61) and configured to interrupt the current path when an internal pressure of a battery container (2) is increased. The current interrupting portion (60) has a diaphragm (68) whose top portion (68a) is electrically connected to the collector plate (21) and whose edge portion (68b) is electrically connected to the external terminal (61). The diaphragm (68) is formed into a convex shape protruding inside the battery container (2) and into a planar shape elongated in a longitudinal direction of the battery container (2).