Cylindrical Battery Cap Plate Welding for Vibration-Resistant Sealing
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Solution Overview
Problem
Cylindrical lithium-ion batteries face issues with poor connection reliability between the cap plate and the case, leading to potential cracking or disconnection under conditions like vibration or pressure, posing significant safety hazards.
Innovation Solution
A battery design featuring a cap plate with an annular protrusion and a cylindrical groove structure case, where the annular protrusion is laser-welded to the case's inner sidewall, providing high connecting strength and hermetic performance without needing groove-rolling, and incorporating supporting blocks for additional structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional assembly methods are used to connect the cap plate to the case, then the assembly process is simple, but the connection reliability is poor and the cap plate may crack or disconnect under vibration or pressure
Solution Approach 1:
The connection structure is segmented into distinct functional zones: the annular protrusion provides mechanical engagement and positioning, while the first welding platform face provides a dedicated laser welding surface. This segmentation allows each component to perform its specific function optimally, ensuring both mechanical strength and welding quality without complicating the overall structure.
Solution Approach 2:
The annular protrusion and first welding platform face are pre-formed on the cap plate during cap plate manufacturing, before assembly with the case. This preliminary preparation ensures that the welding surface is already optimized and positioned correctly, eliminating the need for additional processing steps during assembly and ensuring consistent connection reliability.
2Strength
If the cap plate is subjected to vibration and pressure, then the battery operates under normal conditions, but the poor connection reliability causes cracking or disconnection
Solution Approach 1:
The annular protrusion and first welding platform face are merged into an integrated structure on the cap plate. The protrusion provides mechanical engagement to resist vibration, while the platform face provides a robust welding surface to resist pressure. This merging of mechanical and welding functions into a single integrated feature enhances overall connection strength without increasing complexity.
Solution Approach 2:
The traditional mechanical connection method is replaced with laser welding technology. Instead of relying solely on mechanical fastening that may fail under vibration and pressure, the cap plate is laser-welded to the case, providing a stronger, more reliable connection that resists harmful environmental factors while maintaining structural integrity.
3Reliability
If laser welding is used to connect the annular bottom end face to the first welding platform face, then high connection strength and hermetic performance are achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The first welding platform face is designed with specific local qualities: it is arranged circumferentially around the annular protrusion and forms a stepped face with the outer sidewall of the protrusion. This localized geometric configuration optimizes the welding area for laser welding, ensuring high hermetic performance and connection strength while keeping the rest of the cap plate structure simple and easy to manufacture.
4Manufacturing precision
If an annular protrusion is added to the cap plate, then connection strength and positioning accuracy are improved, but the cap plate structure becomes more complex
Solution Approach 1:
The annular protrusion serves multiple functions simultaneously: it provides mechanical engagement with the case, offers positioning accuracy through its central axis alignment, and creates the stepped face geometry needed for optimal laser welding. This multi-functionality reduces the need for separate features, thereby improving manufacturing precision without significantly increasing overall structural complexity.
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 enhances the connection strength between the cap plate and case, ensuring reliable assembly and improved hermetic performance, reducing internal space loss, and maintaining structural integrity under various conditions.
Implementation Method 1
the annular bottom end face of the case is in contact with the first welding platform face and connected to the first welding platform face by laser welding
Data Source
AI summary
Provided is a battery including a case and a cap plate. The case is a cylindrical groove structure, a top end face, facing towards the case, of the cap plate is provided with an annular protrusion, the annular protrusion has a central axis coinciding with the central axis of the cap plate, an edge of the top end face of the cap plate is provided with a first welding platform face, the first welding platform face is arranged circumferentially around the annular protrusion, and an outer sidewall of the annular protrusion and the first welding platform face constitute a stepped face. The annular protrusion enters the interior of the case via an annular bottom end face of the case, and the annular bottom end face of the case is in contact with the first welding platform face and connected to the first welding platform face by laser welding.