Cylindrical Li-Ion Battery Cap Welding for Vibration-Proof Sealing
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Solution Overview
Problem
Cylindrical lithium-ion batteries in the related art suffer from poor reliability in the connection of the negative cap to the case, leading to potential cracking or disconnection under conditions like vibration and pressure, posing a safety hazard.
Innovation Solution
A cylindrical lithium-ion battery design featuring a negative cap connected to a case via an annular inwardly-concaved groove and annular engaging groove, sealed by laser welding, ensuring a firm and hermetic connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative cap is connected to the case using conventional assembly methods, then the assembly process is simple, but the connection reliability is poor and the negative cap may crack or disconnect under vibration and pressure
Solution Approach 1:
The patent replaces the conventional mechanical assembly connection with laser welding, substituting a mechanical system with a thermal processing system. The laser welding process creates a metallurgical bond between the negative cap and case, eliminating the reliability issues of mechanical connections under vibration and pressure while maintaining structural integrity.
Solution Approach 2:
The patent integrates the negative cap connection structure with the case by forming an annular engaging groove directly on the case sidewall. This merging of components creates a unified structure where the negative cap is both mechanically engaged and laser-welded to the case, improving connection reliability without requiring separate fastening mechanisms.
2Reliability
If the negative cap is connected to the case with a simple structure, then the manufacturing process is easy, but the hermetic performance cannot be ensured
Solution Approach 1:
The patent replaces mechanical assembly methods with laser welding to achieve hermetic sealing between the negative cap and case. The laser welding process creates a continuous, leak-proof seal that ensures hermetic performance while the automated nature of laser welding maintains manufacturing efficiency.
Solution Approach 2:
The patent applies laser welding specifically at the critical sealing interface between the negative cap and case, concentrating the hermetic sealing function at the precise location where it is most needed. The annular engaging groove provides localized structural support exactly where the seal is formed, ensuring hermetic performance without complicating the overall manufacturing process.
3Adaptability or versatility
If the negative cap is subjected to vibration and pressure, then the battery operates under normal conditions, but the connection may fail causing safety hazards
Solution Approach 1:
The patent combines mechanical engagement through the annular engaging groove with laser welding to create a dual-mode connection. This merged approach allows the negative cap to withstand vibration and pressure during normal battery operation while maintaining connection stability, as the laser-welded bond provides superior resistance to mechanical stresses compared to mechanical assembly alone.
Solution Approach 2:
The patent replaces the mechanical assembly connection with laser welding to improve connection stability under vibration and pressure. The metallurgical bond created by laser welding provides superior mechanical strength and resistance to environmental stresses, enabling the battery to operate reliably under various conditions without connection failure.
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 provides a reliable and hermetic connection between the negative cap and case, enhancing safety by preventing disconnection and maintaining structural integrity under various conditions.
Implementation Method 1
a bottom surface of the negative cap and the annular engaging groove are connected in a sealed manner by laser welding
Data Source
AI summary
Provided is a cylindrical lithium-ion battery including a negative cap and a cylindrical case. A jellyroll and a negative current collector are arranged inside the case. A sidewall of an end of the case is provided with an annular inwardly-concaved groove arranged circumferentially around a central axis of the case, and forms an annular protrusion at the inside of the case. The negative current collector is connected to a negative electrode of the jellyroll. A portion, located below the annular inwardly-concaved groove, of the case is bent to form an annular engaging groove, an opening of the annular engaging groove faces the interior of the case, the periphery of the negative cap is arranged in the annular engaging groove, and a bottom surface of the negative cap and the annular engaging groove are connected in a sealed manner by laser welding.