Battery Terminal Uneven Pattern for Crack-Resistant Ultrasonic Joining
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Solution Overview
Problem
In ultrasonic joining devices, the wear of inner protruding portions occurs faster than outermost protruding portions, leading to potential cracks and reduced strength at the joint boundary between gripping and non-gripping regions, particularly in the context of current collectors and terminals of secondary batteries.
Innovation Solution
The design of the anvil's support surface features a central region with first protruding portions and outer regions with larger second protruding portions, along with a specific uneven pattern on the terminal's outer surface, stabilizing the joint by evenly distributing load and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the height of the outermost protruding portion is smaller than the height of the protruding portion on the inner portion, then a crack is suppressed from occurring at the boundary between gripping region and non-gripping region, but the protruding portion on the inner portion wears earlier than the outermost protruding portion
Solution Approach 1:
The invention applies different height configurations to different regions of the protruding portion. The outermost protruding portions are set shorter to prevent cracks at boundaries, while the inner protruding portions are set taller to bear the main load and resist wear during ultrasonic joining operations.
2Duration of action of stationary object
If the height difference between inner protruding portion and outermost protruding portion becomes small, then wear distribution improves, but a crack may occur at the boundary between gripping region and non-gripping region
Solution Approach 1:
The invention maintains a specific height difference between inner and outermost protruding portions. The inner protruding portions have greater height to concentrate load and resist wear, while the outermost protruding portions have reduced height to prevent crack initiation at the gripping region boundary.
3Reliability
If the protruding portion on the inner portion wears earlier, then the height difference decreases, but the strength of the joint portion decreases and the joined state varies
Solution Approach 1:
The invention strategically designs the protruding portions with varying heights where inner portions are taller to withstand wear from ultrasonic vibration, while outermost portions are shorter to prevent crack formation. This local differentiation ensures both joint strength stability and extended service life.
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 configuration stabilizes the joined state between current collectors and terminals, preventing cracks and maintaining joint strength by uniformly distributing wear across the anvil's surface, thus enhancing the durability of secondary battery connections.
Implementation Method 1
an ultrasonic joining device ultrasonically joins a plurality of objects to be joined by pressurizing and vibrating the plurality of objects to be joined
Implementation Method 2
pressurizing and vibrating the plurality of objects to be joined, which are disposed on the anvil in an overlapping manner with the horn
Data Source
AI summary
A secondary battery includes a plurality of current collectors electrically connected to a plurality of electrodes; and a terminal joined to the plurality of current collectors, wherein an outer surface of the terminal at a joint portion between the plurality of current collectors and the terminal has a first uneven region having an uneven shape, the first uneven region has a first uneven pattern having a plurality of first recessed portions; and two second uneven patterns each having a plurality of second recessed portions each having a larger area than an area of each of the first recessed portions in plan view of the outer surface of the terminal, and the first uneven pattern is located between the two second uneven patterns in the plan view.