Battery Cell Cap Venting Structure to Prevent Can Side Wall Rupture
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Solution Overview
Problem
Cylindrical lithium-ion batteries face a high risk of side wall rupture during thermal runaway due to narrow venting passages, which can propagate thermal runaway across the battery pack and compromise user safety.
Innovation Solution
A battery cell structure that includes a cap with a loop-shaped fracture inducement portion and a current collector plate with a can connection portion, allowing for increased diameter of the fracture inducement portion and minimizing direct contact of gases and flames with the side wall, thereby preventing rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crimping structure is applied to fix the cap to the can, then the cap is securely fixed to the can, but the diameter of the fracture inducement portion is reduced causing narrow venting passages
Solution Approach 1:
The invention divides the cap structure into distinct functional segments: a cap body portion that provides secure fixation to the can, and a fracture inducement portion with enlarged diameter that provides adequate venting area. This segmentation allows each part to optimize its specific function without compromising the other.
Solution Approach 2:
The invention extends the fracture inducement portion outward from the cap body in the radial direction, creating a dimensional transition from a compact cap structure to an expanded venting structure. This dimensional change increases the venting passage area while maintaining secure cap fixation through the cap body portion.
2Reliability
If beading portion is formed to connect current collector plate, then electrical connection is achieved, but venting passages become bottlenecked causing side wall rupture
Solution Approach 1:
The invention introduces a bridge structure as an intermediary element that connects the current collector plate to the can or cap. This bridge structure provides a dedicated electrical connection path while being positioned away from the venting passages, thereby preventing bottleneck effects and reducing the risk of side wall rupture during thermal runaway.
Solution Approach 2:
The invention extracts the electrical connection function from the cap structure by using a separate current collector plate with bridge structure. This separation allows the cap structure to focus on providing adequate venting area through the enlarged fracture inducement portion, while electrical connection is achieved through the dedicated bridge structure.
3Strength
If cap edge is crimped inward to fix to can, then cap is securely attached, but fracture inducement portion diameter is limited
Solution Approach 1:
The invention segments the cap structure into a cap body portion for secure attachment and a fracture inducement portion for venting. The cap body portion can be crimped inward to provide strong attachment, while the fracture inducement portion extends outward to provide adequate diameter for safe venting operations.
Solution Approach 2:
The invention utilizes radial extension to increase the fracture inducement portion diameter without compromising the cap-to-can attachment strength. The cap body portion maintains the attachment function through crimping, while the radially extended fracture inducement portion provides the necessary dimensional space for safe venting.
Data Source
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AI summary
The present disclosure provides a battery cell including a can including a side wall extended in an axial direction, and an open end portion at an end portion of the side wall in the axial direction; a cap that covers the open end portion; an electrode assembly housed in the can; and a current collector plate electrically connecting the electrode assembly and the can, wherein an edge of the cap is joined to the end portion of the side wall in the axial direction, the cap includes a loop-shaped fracture inducement portion that is concentric with the edge of the cap, the current collector plate includes a body portion connected to an electrode tab of the electrode assembly; a loop-shaped can connection portion disposed on a more centrifugal side than the body portion and joined to at least one of the side wall or the cap; and a bridge having a centripetal side connected to the body portion and a centrifugal side connected to the can connection portion and extended in a radial direction, and the fracture inducement portion of the cap is disposed at an outer position than a centripetal side edge of the can connection portion in the radial direction.