Cylindrical Battery Cap Assembly Notch and Surface Treatment
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Solution Overview
Problem
Cylindrical lithium ion secondary batteries face challenges in safety, capacity, scratch resistance, and pressure resistance, particularly on their external contact surfaces.
Innovation Solution
A cylindrical secondary battery design featuring a cap assembly with a top plate having a notch and surface-treated regions, including knurling or embossing, which allows for enhanced safety by blocking current paths and releasing internal gas when pressure exceeds a certain threshold, while reducing size and increasing capacity through a reduced cap assembly height and improved surface durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cap assembly height is reduced to increase battery capacity, then the battery capacity increases, but the scratch resistance and pressure resistance of the external contact surface deteriorate
Solution Approach 1:
The patent applies surface treatment (knurling or embossing) to create a concave-convex structure on the top plate surface. This local modification enhances scratch resistance and pressure resistance at the external contact surface without affecting the overall cap assembly height, thus resolving the contradiction between increasing battery capacity and maintaining surface durability.
2Ease of manufacture
If a smooth surface is used on the top plate to maintain manufacturing simplicity, then manufacturing is easier, but scratch resistance and pressure resistance are reduced
Solution Approach 1:
The patent modifies the surface parameters of the top plate by introducing a concave-convex structure through knurling or embossing treatment. This changes the surface topology from smooth to textured, significantly improving scratch resistance and pressure resistance while maintaining compatibility with existing manufacturing processes.
3Reliability
If the cap assembly is designed with a notch for safety pressure release, then safety is improved, but the structural integrity and strength of the cap assembly may be compromised
Solution Approach 1:
The patent incorporates a notch in the top plate that serves as a predetermined weak point for safety pressure release. This preliminary structural feature allows the cap assembly to safely vent internal pressure when gas generation exceeds a certain threshold, preventing catastrophic failure while maintaining overall structural integrity through proper notch design and positioning.
Data Source
AI summary
The present invention provides a cylindrical secondary battery which can have increased safety and capacity, and enhanced scratch resistance and pressure resistance on an external contact surface. To this end, a cylindrical secondary battery is disclosed, the battery comprising: a cylindrical case; an electrode assembly received in the case; and a cap assembly for sealing the case, wherein the cap assembly comprises a top plate having a notch formed on at least one surface thereof, a middle plate coupled to the top plate and including a first through-hole formed through the center thereof, and a bottom plate electrically connected with the electrode assembly and coupled to the top plate through the first through-hole of the middle plate, and includes a surface-treated region formed by surface-treating a surface of the top plate so as to have a concave-convex structure.