Cylindrical Cell Terminal Surface for Laser Welding and Wire Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current rechargeable batteries, particularly lithium-ion batteries, face challenges in improving safety and production complexity, as well as energy density and power, which are not adequately addressed by existing mechanical and chemical changes.
Innovation Solution
A cylindrical secondary cell with a terminal surface featuring two distinct surface roughness areas, allowing for different connection methods such as laser welding and wire bonding, enhancing mechanical strength and assembly processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform smooth terminal surface is used, then laser welding quality is improved, but wire bonding strength deteriorates
Solution Approach 1:
The terminal surface is divided into two distinct regions: a first region with smooth surface finish (Ra ≤ 0.8 μm) optimized for laser welding, and a second region with rough surface finish (Ra ≥ 3.2 μm) optimized for wire bonding. This local differentiation allows each connection method to operate under its optimal surface conditions simultaneously on the same terminal component.
2Strength
If a rough terminal surface is used, then wire bonding strength is improved, but laser welding quality deteriorates
Solution Approach 1:
The terminal surface is divided into two distinct regions: a first region with smooth surface finish (Ra ≤ 0.8 μm) optimized for laser welding, and a second region with rough surface finish (Ra ≥ 3.2 μm) optimized for wire bonding. This local differentiation allows each connection method to operate under its optimal surface conditions simultaneously on the same terminal component.
3Adaptability or versatility
If multiple connection methods are supported on the terminal surface, then adaptability is improved, but device complexity increases
Solution Approach 1:
The terminal surface is segmented into two functional zones with distinct surface characteristics. The smooth first region and rough second region are clearly demarcated, allowing different connection methods to be applied to appropriate regions without interfering with each other, thereby supporting multiple connection methods while maintaining manageable complexity.
Solution Approach 2:
The terminal surface is divided into two distinct regions: a first region with smooth surface finish (Ra ≤ 0.8 μm) optimized for laser welding, and a second region with rough surface finish (Ra ≥ 3.2 μm) optimized for wire bonding. This local differentiation allows each connection method to operate under its optimal surface conditions simultaneously on the same terminal component.
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 dual roughness terminal surface enables efficient and robust connections, improving the mechanical strength of bonds and facilitating easier handling and assembly of the battery cells.
Implementation Method 1
A first surface roughness of the first part exceeds a second surface roughness of the second part by more than a predetermined amount. Due to the roughness of the surface, more material is engaged in the wire bonding, resulting in a larger overall bonding surface, which gives an increased mechanical strength of the bond.
Implementation Method 2
When laser welding, it is beneficial to have a smooth surface to minimize the cabs between the materials to be welded together.
Data Source
AI summary
The disclosure shows a cylindrical secondary cell (1) comprising a cylindrical can (2) comprising an end side (2a), and a terminal (3), arranged at the can end side (2a). The terminal (3) comprises a terminal surface (4) for connecting external electrical interconnects to the cylindrical secondary cell (1). The terminal surface (4) comprises a first part (4a) formed by a centre region of the terminal surface and being at least partly surrounded by a second part (4b) of the terminal surface, wherein a first surface roughness of the first part (4a) exceeds a second surface roughness of the second part (4b).