Cylindrical Battery Terminal Structure for External Collector Welding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cylindrical secondary batteries face complications in manufacturing due to complex structures and increased process times for connecting busbars, and welding defects occur due to misalignment and insufficient welding areas, which can damage the electrode assembly and introduce impurities.
Innovation Solution
The design includes a welding groove in the lower terminal outside the case, allowing the current collector plate to be welded outside the case, and an upper terminal that fills the groove, ensuring a flat top surface for alignment and preventing welding defects and impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is performed inside the case through a groove outside the rivet terminal, then electrical connection is achieved, but welding impurities are generated inside the case and the electrode assembly may be damaged by welding heat
Solution Approach 1:
The welding operation is extracted from the interior of the case and relocated to the exterior. The terminal is designed with a protruding portion that extends beyond the case opening, allowing the current collector plate to be welded to this external portion. This extraction eliminates the harmful effects of welding impurities and heat from the electrode assembly interior while maintaining reliable electrical connection.
2Ease of manufacture
If a groove is provided outside the rivet terminal for welding, then welding is enabled, but alignment errors occur during busbar connection leading to insufficient welding area and welding defects
Solution Approach 1:
The terminal's protruding portion is pre-positioned and pre-aligned relative to the case opening before the welding process. This preliminary positioning ensures that when the current collector plate is welded to the protruding portion, the alignment is already optimized, preventing misalignment errors and welding defects during busbar connection.
Solution Approach 2:
The protruding portion of the terminal acts as an intermediary element between the case and the current collector plate. It provides a dedicated welding surface that is geometrically optimized for alignment, serving as a mediator that ensures precise positioning and high-quality welding while eliminating the alignment issues associated with grooves outside the rivet terminal.
3Device complexity
If the terminal structure is simplified to facilitate busbar connection, then manufacturing complexity is reduced, but welding area may be insufficient leading to increased resistance
Solution Approach 1:
The terminal design utilizes the dimensional space outside the case opening by creating a protruding portion that extends in the direction perpendicular to the case surface. This dimensional extension provides additional welding area without increasing the terminal's footprint within the case, thereby maintaining low complexity while ensuring sufficient welding area and low electrical resistance.
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
This design prevents welding defects and impurities within the case, maintaining the integrity of the electrode assembly and facilitating efficient connection of multiple batteries through busbars.
Implementation Method 1
welding may be performed between the rivet terminal and the current collector plate of the electrode assembly through a groove provided outside the rivet terminal
Implementation Method 2
a welding groove provided in a lower terminal is filled by an upper terminal so that a top surface of a terminal has an approximately flat top surface, and thus, if a plurality of secondary batteries are welded through a busbar
Data Source
AI summary
A cylindrical secondary battery includes an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly and having a lower end that is open and electrically coupled to the second electrode plate; a first current collector plate between a top surface of the electrode assembly and the case and that is electrically connected to the first electrode plate; a terminal passing through a top surface of the case and including a lower end electrically and mechanically coupled to a top surface of the first current collector plate; and a cap plate configured to seal the lower end of the case. The terminal includes a lower terminal including a welding groove having a depth from a top surface of the terminal in a downward direction; and an upper terminal in the welding groove of the lower terminal.