Composite Cell Connector for Dissimilar Metal Poles
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Solution Overview
Problem
Existing cell connectors made of different materials, such as copper and aluminum, face issues with incompatibility, corrosion, and high contact resistance, leading to inefficient current transfer and stability problems, especially in high-performance lithium-ion battery stacks.
Innovation Solution
A composite cell connector is designed using two bundles of stranded wires made of different materials, which are axially offset and can be cold-welded, with conductive solder-like material introduced in cavities to reduce contact resistance and enhance mechanical flexibility, and optionally sealed with a sleeve or cap for improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-material cell connectors are joined using laser induction welding or roll plating, then material compatibility and electrical conductivity are improved, but manufacturing complexity and production difficulty increase
Solution Approach 1:
The cell connector is divided into multiple individual wire strands instead of a solid two-material construction. Each strand can be independently processed and assembled, simplifying the manufacturing process while maintaining material compatibility at connection points.
Solution Approach 2:
The invention uses composite construction with copper-coated steel strands combined with aluminum strands. The copper coating on steel strands provides compatibility with copper poles, while aluminum strands connect to aluminum poles, achieving material compatibility without complex welding or plating processes.
2Reliability
If flat connections are used between dissimilar metals, then material compatibility is achieved, but mechanical strength and contact stability deteriorate under vibration stress
Solution Approach 1:
The invention replaces flat connections with rounded wire strands. The curved surface geometry of individual wires provides better contact pressure distribution and mechanical interlocking compared to flat surfaces, improving peel strength and vibration resistance.
Solution Approach 2:
The invention changes the physical state from rigid flat plates to flexible stranded wire construction. This parameter change allows the connection to accommodate mechanical stress through strand deformation rather than rigid flat surface contact, maintaining stability under vibration.
3Reliability
If plated contact surfaces are used for dissimilar metals, then material compatibility is achieved, but electrical contact resistance increases over time due to creeping under vibration
Solution Approach 1:
The rounded wire strands create point contacts that maintain higher contact pressure under vibration compared to flat surfaces. This prevents the creeping phenomenon that increases resistance in plated connections, maintaining low electrical contact resistance over time.
Solution Approach 2:
The copper-coated steel strands provide inherent material compatibility with copper poles, eliminating the need for plated surfaces that are prone to resistance increase. The direct metal-to-metal contact between compatible materials maintains stable electrical properties.
4Stability of the object's composition
If rigid multi-material elements are used, then structural stability is achieved, but mechanical flexibility and adaptability are reduced
Solution Approach 1:
The cell connector is segmented into multiple independent wire strands rather than a rigid monolithic structure. This segmentation allows individual strands to flex and deform independently, providing mechanical flexibility while the overall bundle maintains structural stability.
Solution Approach 2:
The stranded wire construction acts as a flexible structure compared to rigid plates. The thin wire strands can bend and adapt to mechanical stresses while maintaining electrical conductivity, providing both flexibility and structural integrity.
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 achieves low and stable contact resistance, improved mechanical flexibility, and enhanced long-term reliability, overcoming the limitations of previous technologies by allowing for efficient current transfer and reduced Joule heating.
Implementation Method 1
conductive solder-like material introduced in cavities to reduce contact resistance
Implementation Method 2
which are axially offset and can be cold-welded
Data Source
Figure 1~2
Figure 3~4
AI summary
A multi-material cell connector (12) for material-compatible connection to the different materials of the two poles (13) of cells (11) that are to be series-connected is designed as a strand (14) of two bundles (15) of litz wires (16) which are offset relative to one another and longitudinally in contact with each other, or of braids of litz wires (16), said litz wires being made of materials that are compatible with the poles (13), e.g. copper and aluminum, and being cold-welded to each other in at least some regions by radially applying energy.