Cylindrical Battery Can Structure for Thermal Runaway Pressure Redirection
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Solution Overview
Problem
Cylindrical secondary batteries used in vehicles face safety issues due to potential side surface damage and chain ignition during high-temperature exposure, necessitating a solution to prevent damage to the side surface and redirect pressure during internal ignition.
Innovation Solution
A secondary battery design with a metal can body and a lower-melting-point metal member inserted in the bottom and crimping parts, redirecting pressure to the upper and lower ends to minimize side surface damage and prevent chain ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal can body is used for cylindrical secondary batteries, then structural strength and durability are improved, but the side surface may be damaged during high-temperature exposure leading to chain ignition
Solution Approach 1:
The patent applies local quality by inserting metal members with lower melting points specifically at the top and bottom ends of the can body, creating localized weak points that differ from the main body structure. This allows the ends to deform preferentially under thermal stress, redirecting pressure away from the side surface while maintaining the overall structural integrity of the can body.
Solution Approach 2:
The metal members inserted at the ends act as beforehand cushioning elements that are designed to deform or melt first during thermal runaway events. This pre-planned deformation mechanism cushions the pressure buildup and redirects it to safe areas (the ends), preventing the harmful effect of side surface damage before it can occur.
2Stability of the object's composition
If pressure is uniformly distributed during internal ignition, then structural integrity is maintained, but the side surface of the can body is damaged leading to chain ignition
Solution Approach 1:
The patent segments the pressure distribution function by introducing metal members at specific locations (ends) that will deform preferentially. This segmentation creates designated pressure release zones at the ends, separating the pressure-bearing function from the side surface and concentrating deformation in specific segments, thereby protecting the overall structural integrity while preventing chain ignition.
Solution Approach 2:
The metal members with lower melting points serve as intermediary elements between the internal ignition pressure and the can body structure. These intermediaries deform or melt first, mediating the pressure transfer and redirecting it away from the side surface, thus protecting the main structural integrity while safely dissipating the harmful pressure.
3Strength
If the can body structure is reinforced to prevent deformation, then mechanical strength is improved, but pressure during internal ignition cannot be released leading to side surface damage
Solution Approach 1:
The patent applies local quality by creating localized areas with different mechanical properties (the metal members at ends) compared to the main can body. This allows the ends to have controlled deformability for safety while the main body maintains high mechanical strength, resolving the contradiction between overall strength and localized pressure release capability.
Solution Approach 2:
The patent changes the material parameter (melting point) of specific components at the ends to be lower than the can body material. This parameter change creates a controlled weakness at the ends that allows pressure release during thermal runaway, while the can body itself maintains its high mechanical strength for normal operation and structural integrity.
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 design effectively minimizes pressure on the side surface of the can body, reducing the risk of secondary battery ignition and enhancing overall safety by redirecting pressure to the upper and lower ends during internal ignition.
Implementation Method 1
the metal member has a lower melting point than the metal of the can body
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
The present disclosure provides a secondary battery in which an electrode assembly including a cathode, a separator and an anode is housed in a battery case together with an electrolytic solution, wherein the battery case is made of metal, wherein the battery case includes a can body that includes a housing part for housing the electrode assembly and the electrolytic solution and is opened in its upper part; and a cap assembly that is coupled to the opened upper part of the can body; wherein the can body includes a beading part that is bent inward at the upper part of the housing part, and a crimping part that is bent in a direction in which the cap assembly is located at an upper part of the beading part, wherein at least one of the bottom part or the crimping part of the can body has a metal member inserted therein, and wherein the metal member has a lower melting point than the metal of the can body.