Prismatic Battery Case Coupling to Prevent Cap Plate Over-Insertion
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Solution Overview
Problem
Existing secondary batteries face issues with cap plate over-insertion, which can cause the electrode assembly to be dented, and scratch burrs on the case due to the larger cap plate size.
Innovation Solution
A secondary battery design featuring a case with a concave coupling portion that includes an inclined surface, connection surface, and stepped portion, which prevents cap plate over-insertion and reduces scratch burrs by providing a secure press-fitting mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cap plate is made larger in size than the case for press fitting coupling, then the coupling strength is improved, but the cap plate is prone to over-insertion which may dent the electrode assembly
Solution Approach 1:
The coupling portion is divided into multiple functional surfaces: an inclined surface for guiding insertion, a connection surface for establishing contact, and a stepped portion for limiting insertion depth. This segmentation allows the cap plate to be securely coupled while preventing over-insertion that would dent the electrode assembly.
Solution Approach 2:
The coupling structure transitions from a simple flat interface to a multi-level three-dimensional structure with varying heights and angles. The stepped portion creates a vertical dimension that physically stops the cap plate at the correct insertion depth, preventing over-insertion while maintaining coupling strength.
2Strength
If the cap plate is larger in size than the case, then the coupling strength is improved, but the coupling portion of the case may be scratched causing scratch burrs or damage
Solution Approach 1:
The inclined surface provides a curved, tapered transition that guides the cap plate into the coupling portion smoothly. This curved interface distributes the insertion force evenly and prevents sharp edges from scratching the case, eliminating scratch burrs while maintaining coupling strength.
3Strength
If welding is used to couple the cap plate to the case, then the coupling strength is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the welding process (thermal/chemical joining) with a purely mechanical press-fitting system. The multi-surface coupling structure provides sufficient coupling strength through mechanical interference and friction, eliminating the need for welding equipment, skilled welders, and post-weld inspection processes.
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 improved coupling structure effectively prevents cap plate over-insertion and electrode assembly denting, while reducing scratch burrs and enhancing the secure fixation of the cap plate without the need for welding.
Implementation Method 1
the coupling portion may include an inclined surface, a connection surface, and a stepped portion. The inclined surface may be formed to be inclined downward from an upper end of the case.
Implementation Method 2
The cap plate may be coupled to the coupling portion by press fitting.
Data Source
AI summary
A secondary battery includes: a case having a prismatic shape; an electrode assembly in the case; and a cap assembly including a cap plate coupled to one end of the case, wherein the case includes a coupling portion provided in a shape concave from an inner surface toward an outer side along an upper region of at least some surfaces thereof, and the coupling portion includes an inclined surface, a connection surface, and a stepped portion.