Cylindrical Battery Terminal Structure for Debris-Free Welding
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Solution Overview
Problem
Cylindrical secondary batteries face issues with damage, leakage, and complex busbar connections due to improper welding and riveting, leading to increased resistance and manufacturing complexity.
Innovation Solution
A cylindrical secondary battery design with a terminal recess in the lower terminal, allowing for welding of the terminal and current collector plate without debris generation, and a pressing portion with corrugations to ensure proper alignment and sealing, along with insulating members to prevent electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal and current collector plate are welded inside the case, then electrical connection is achieved, but welding debris is generated inside the case and electrode assembly is damaged by welding heat
Solution Approach 1:
The patent extracts the welding operation from the interior space of the case and relocates it to the exterior. The terminal extends outward from the case, and the welding between the terminal and current collector plate is performed outside the case, thereby preventing welding debris and heat from affecting the electrode assembly inside the case while maintaining electrical connection functionality.
Solution Approach 2:
The terminal acts as an intermediary component that bridges the electrical connection between the current collector plate and external circuits. By positioning the terminal to extend through the case wall, it serves as a mediator that allows welding to occur externally while still achieving the required electrical connectivity, thus isolating the sensitive electrode assembly from harmful welding effects.
2Ease of manufacture
If the terminal recess is left empty, then manufacturing is simpler, but welding misalignment occurs and resistance increases
Solution Approach 1:
The terminal recess is pre-formed in the terminal body before the welding operation. This preliminary structural preparation provides a precise guide and positioning feature that ensures proper alignment during the welding process. The recess acts as a pre-prepared receptacle that guides the welding tool and maintains correct positioning, thereby preventing misalignment and reducing resistance without significantly complicating manufacturing.
Solution Approach 2:
The terminal recess introduces local structural differentiation in a specific area of the terminal where welding occurs. This localized feature provides enhanced alignment precision and welding surface quality only where needed, while the rest of the terminal maintains its simple cylindrical form. This approach improves welding reliability without requiring complex modifications throughout the entire terminal structure.
3Ease of manufacture
If the pressing portion is not bent and overlapped, then manufacturing is simpler, but sealing is difficult and damage or leakage occurs
Solution Approach 1:
The pressing portion is bent into a curved or overlapped configuration rather than remaining straight. This curvature allows the pressing portion to conform to the sealing surface and create effective sealing contact. The bent shape enables the pressing portion to apply distributed pressure across the sealing interface, preventing leakage while maintaining a relatively simple manufacturing process that only requires bending and overlapping.
Solution Approach 2:
The pressing portion is folded back and overlapped with itself, merging two layers of the same material. This overlapping configuration creates a multi-layer sealing structure that enhances sealing performance through increased contact area and pressure distribution. The merged structure achieves reliable sealing without introducing additional separate components, thus maintaining manufacturing simplicity.
Data Source
AI summary
Disclosed is a cylindrical secondary battery including an electrode assembly having a first electrode plate, a separator, and a second electrode plate; a case configured to receive the electrode assembly, wherein a lower end of the case is open, the case being electrically connected to the second electrode plate; a first current collector plate interposed between the electrode assembly and the case, the first current collector plate being electrically connected to the first electrode plate; a terminal extending through an upper surface portion of the case, the terminal having a lower end coupled to an upper surface of the first current collector plate; and a cap plate configured to seal the case, wherein the terminal includes a head located above the upper surface portion of the case, a fastening portion extending through the case, and a pressing portion located under the upper surface portion of the case.