Segmented Core Member for Cylindrical Lithium Battery Impact Resistance
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Solution Overview
Problem
Cylindrical lithium ion secondary batteries face instability and safety issues due to external pressure, which can cause the core member to deform, damage the separator, and lead to shorts or explosions, especially when it collides with the cap assembly or rotates within the electrode assembly.
Innovation Solution
The battery design incorporates a core member formed in a tubular shape with a gap along the longitudinal direction, featuring notches and bending portions to distribute pressure and prevent deformation, and a cap assembly connected to the case to seal the battery, ensuring the core member is securely positioned and reducing the risk of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a solid core member is inserted into the electrode assembly to maintain structural stability, then the electrode assembly is prevented from deforming during charge/discharge, but the core member may move or rotate under external impact, causing damage to the cap assembly or electrode assembly
Solution Approach 1:
The core member is divided into multiple segments along its longitudinal axis, with gaps between the segments. This segmentation allows the core member to absorb external impact forces through relative movement between segments, preventing the core member from rotating or moving as a rigid body while still maintaining structural support for the electrode assembly.
Solution Approach 2:
The core member's physical structure is changed from a solid continuous form to a segmented form with controlled gaps. This parameter change enables the core member to transition from a rigid structure to one that can flexibly respond to external forces, improving safety under impact while maintaining structural stability during normal operation.
2Strength
If the core member is made rigid to prevent deformation under external pressure, then structural support is maintained, but the core member may be deformed in a specific direction at concentrated pressure points, causing shorts between electrode plates
Solution Approach 1:
The core member is segmented into multiple sections with gaps between them. This segmentation allows each segment to independently respond to external pressure, distributing the stress across multiple contact points rather than concentrating it at single points, thereby preventing localized deformation that could cause shorts.
Solution Approach 2:
The gaps between core member segments act as pre-designed cushioning spaces that can compress or expand under external pressure. This beforehand cushioning allows the core member structure to absorb and distribute pressure forces before they can concentrate at specific points, preventing deformation that would lead to electrode plate shorts.
3Stability of the object's composition
If the core member is designed as a complete tube to maintain structural integrity, then the electrode assembly is well-supported, but the core member may collide with the cap assembly under external impact, inverting or damaging the safety belt
Solution Approach 1:
The core member is divided into segments with gaps between them, which allows the structure to flex and absorb impact forces. This segmentation prevents the core member from acting as a rigid lever that could amplify impact forces and collide with the cap assembly, while still maintaining sufficient structural integrity to support the electrode assembly.
Solution Approach 2:
The core member transitions from a static rigid structure to a dynamic segmented structure that can move and flex in response to external forces. The gaps between segments allow controlled movement that absorbs impact energy, preventing the core member from colliding with the cap assembly while maintaining structural support during normal operation.
Data Source
AI summary
A cylindrical lithium secondary battery includes an electrode assembly which has a first electrode plate, a second electrode plate, and a separator provided between the first electrode plate and the second electrode plate, is wound in a spiral shape, and has a central space at the center of winding; a core member which is inserted into the central space of the electrode assembly; a case having a space for containing the electrode assembly; and a cap assembly which is connected to an upper portion of the case so as to seal the case. The core member is formed in a tube shape having a gap along a longitudinal direction, which divides the core member into a body portion and left and right lateral end portions, wherein an imaginary arc line extending from an outer circumferential surface of the body portion of the core member defines an imaginary circumference, and wherein the left and right lateral end portions are located inside the imaginary circumference and comprise a pair of first bending portions, inwardly bending and symmetrically disposed with respect to the gap, and a pair of second bending portions bending in a rotation direction that is opposite to the inwardly bending rotational directions of the first bending portions.