Secondary Battery Cap Assembly with Reinforcing Ring
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Solution Overview
Problem
Lithium secondary batteries are vulnerable to shock and compression, leading to deformation of the electrode assembly and potential shorts between electrode plates, which can cause ignition or explosion during longitudinal compression tests.
Innovation Solution
A secondary battery design featuring a can with a reduced step difference and a cap assembly with a supporter and bottom protrusion to prevent deformation damage, ensuring the cap assembly is securely assembled and reducing the risk of electrode plate shorts during compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap assembly is made thicker to ensure secure assembly to the can, then the assembly reliability is improved, but the battery becomes more vulnerable to deformation under compression
Solution Approach 1:
The cap assembly is segmented into a cap body and a separate reinforcing ring that can be independently optimized. The reinforcing ring provides additional structural support without increasing the overall thickness of the cap assembly, thereby maintaining compression resistance while ensuring secure assembly.
Solution Approach 2:
The cap assembly uses composite structure combining the cap body and reinforcing ring made of different materials with complementary properties. The reinforcing ring provides enhanced mechanical strength and rigidity without adding significant thickness, resolving the contradiction between assembly reliability and shape stability.
2Reliability
If the step difference height is increased to ensure cap assembly seating, then the assembly reliability is improved, but the electrode assembly deforms under compression causing shorts
Solution Approach 1:
The reinforcing ring acts as an intermediary element between the cap body and the electrode assembly. It provides the necessary structural support for secure assembly while preventing direct transmission of compression forces to the electrode assembly, thereby preventing deformation and shorts.
Solution Approach 2:
The reinforcing ring is installed beforehand to cushion and distribute compression forces before they reach the electrode assembly. This preemptive structural support prevents the step difference from deforming inward under compression, maintaining electrode assembly integrity.
3Quantity of substance
If the battery is made thinner to increase energy density, then the energy density is improved, but the battery becomes more vulnerable to shock and compression
Solution Approach 1:
The reinforcing ring provides localized structural reinforcement at the cap assembly where compression forces are most concentrated. This allows the rest of the battery to remain thin for high energy density, while the critical area gains enhanced strength and compression resistance.
Solution Approach 2:
Instead of increasing the overall battery thickness to improve compression resistance, the reinforcing ring adds structural strength in a different dimensional configuration - a circumferential reinforcement that provides rigidity without increasing the axial thickness of the battery.
Data Source
AI summary
A secondary battery including: an electrode assembly including a first electrode plate, a second electrode plate, and a separator interposed between the first electrode plate and the second electrode plate; a can accommodating the electrode assembly and an open end; and a cap assembly to seal the open end of the can. A step difference is formed in an upper end of the can. A supporter settled in the step difference is formed in the cap assembly. A bottom protrusion inserted into the can is formed on a bottom surface of the supporter. Therefore, ignition and explosion are prevented by a short between the electrode plates in accordance with the deformation of the electrode assembly so that the stability of the secondary battery may be improved.