Cold Spray Battery Interconnects for Oxide-Free Bonding
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Solution Overview
Problem
Traditional methods for connecting lithium ion pouch cell electrode tabs to a bus bar, such as fastened threaded studs and ultrasonic welding, face issues like mechanical inconsistencies, high contact resistance, and oxidation, while thermal spray deposition methods expose the cells to high temperatures and result in oxide depositions, compromising the cell's integrity.
Innovation Solution
The use of mechanically bound solid metal particles to fill perforations in the electrode tabs, creating a strong and oxide-free connection with the bus bar, allowing for efficient electrical bonding without the need for high-temperature processes, using a cold spray deposition method that maintains the particles in a solid state to prevent oxidation and ensure a robust joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal spray deposition is used to provide battery interconnects, then the bonding process can be achieved, but the pouch cell is exposed to temperatures of up to 20,000° C. and bonds may suffer from oxide depositions
Solution Approach 1:
The patent changes the temperature parameter from high (thermal spray at 20,000° C.) to low (cold spray near ambient temperature), fundamentally altering the deposition process to avoid oxidation while maintaining bonding effectiveness. This parameter change resolves the contradiction by achieving bond strength without the harmful thermal and oxidative effects.
Solution Approach 2:
The cold spray process operates in a controlled atmosphere that prevents oxidation during deposition. By creating an inert or low-oxygen environment during the bonding process, the patent eliminates oxide depositions while maintaining strong metallurgical bonds between the interconnect and battery terminals.
2Reliability
If traditional fastened threaded studs or ultrasonically welded tabs are used, then electrical connection can be achieved, but mechanical inconsistencies and high contact resistance occur
Solution Approach 1:
The patent replaces traditional mechanical fastening systems (threaded studs) and ultrasonic welding with a cold spray deposition system. This substitution eliminates the mechanical inconsistencies and contact resistance issues associated with traditional methods by creating a metallurgical bond through particle impact and deformation at the interface, resulting in more uniform and reliable electrical connections.
Solution Approach 2:
The cold spray process creates a composite structure at the bond interface, combining the substrate material with deposited particles that form a metallurgical bond. This composite structure provides both mechanical strength and low contact resistance, resolving the contradiction between connection reliability and manufacturing precision.
3Object-affected harmful factors
If cold spray deposition is used to form interconnects, then oxide-free bonds are achieved, but the process requires precise control of particle velocity and temperature
Solution Approach 1:
The cold spray process utilizes the kinetic energy of the particles themselves to achieve bonding, eliminating the need for external heating sources or complex control systems. The particles self-accelerate through the supersonic nozzle and self-bond upon impact, reducing device complexity while maintaining oxidation-free bonds.
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 solution provides a dense, low-porosity, and oxidation-free interconnect with superior corrosion resistance and reduced electrical resistance, enhancing the reliability and longevity of lithium ion pouch cell battery packs by eliminating the risks associated with high-temperature processes and mechanical inconsistencies.
Implementation Method 1
The particles are propelled through a supersonic nozzle and deposited onto the substrate, forming a coating or overlay. The particles remain in a solid state throughout the process, bonding to the substrate through mechanical interlocking and deformation upon impact.
Implementation Method 2
respective agglomerations of mechanically bound solid metal particles each filling one of the perforations to mechanically bind and electrically connect the tabs to the bus bar
Data Source
AI summary
A battery pack includes a pouch cell having electrode tabs extending therefrom, each of the tabs defining perforations, a bus bar in contact with the tabs, and respective agglomerations of mechanically bound solid metal particles each filling one of the perforations to mechanically bind and electrically connect the tabs to the bus bar.