Secondary Cell Current Collector Terminal Welding
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Solution Overview
Problem
In secondary cell manufacturing, the fusion zone of current collector foils and terminals shrinks during solidification, leading to tensile stress that can cause tears in the unfused parts of the current collector foils, increasing resistance and decreasing weld strength.
Innovation Solution
A manufacturing method where a current collector terminal with a specific cutout structure is used, allowing the current collector foils to be welded in a way that reduces the volume of the fusion zone and disperses tensile stress, preventing damage by having a thin-walled part with a smaller thickness than the base part and forming a weld along the second end portion with a smaller length than the first end portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the current collector foils and terminal are welded together by fusing and solidifying, then the joint strength is improved, but the fusion zone shrinks during solidification causing tensile stress that tears the unfused parts of the current collector foils
Solution Approach 1:
The current collector terminal is divided into multiple parts: a base part and multiple thin-walled parts extending in different directions. This segmentation allows the welding structure to distribute the fusion zone and reduce concentrated shrinkage stress, preventing tears in the current collector foils while maintaining joint strength.
Solution Approach 2:
Different parts of the current collector terminal have different thicknesses and structures. The thin-walled parts have smaller thickness than the base part, creating local variations in the welding structure. This local quality difference allows controlled fusion zones that minimize shrinkage stress concentration while ensuring adequate joint strength at critical locations.
2Object-affected harmful factors
If the fusion zone volume is reduced to prevent tearing, then the tensile stress is decreased, but the weld strength may be compromised
Solution Approach 1:
The terminal structure is segmented into a base part providing structural strength and thin-walled parts providing controlled fusion zones. This segmentation allows the fusion zone volume to be reduced in specific areas to minimize tensile stress, while the base part maintains overall weld strength through its larger cross-section and structural integrity.
Solution Approach 2:
The thin-walled parts extend in different directions from the base part with asymmetric configurations. This asymmetric structure creates optimized fusion zones that reduce tensile stress in critical areas where foils are most vulnerable, while maintaining adequate weld strength through the base part's larger dimensions and the distributed nature of the thin-walled extensions.
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 method effectively prevents tears in the current collector foils and enhances the joint strength of the secondary cell by reducing tensile stress and solidification shrinkage, thereby maintaining low resistance and high weld quality.
Implementation Method 1
welding the plurality of current collector foils to the current collector terminal by scanning the plurality of current collector foils disposed in the cutout with an energy beam along the first extension direction toward the second end portion while irradiating the plurality of current collector foils with the energy beam
Data Source
AI summary
A secondary cell manufacturing method includes placing a current collector terminal on a plurality of laminated current collector foils from a lamination direction of the current collector foils. The current collector terminal has a first end portion, and a second end portion forming a cutout with the first end portion. The second end portion includes a base part, and a thin-walled part having a smaller thickness than the base part. The secondary cell manufacturing method includes welding the plurality of current collector foils to the current collector terminal by scanning the plurality of current collector foils disposed in the cutout with a laser beam along the first extension direction toward the second end portion while irradiating the plurality of current collector foils with the laser beam.