Meaning
This electrochemical wear process occurs when two dissimilar metals are in electrical contact within a shared corrosive electrolyte, causing the more active metal to corrode. In battery pack construction, galvanic corrosion can degrade the mechanical and electrical connections between cells and housing plates. Engineers design assembly junctions to isolate different metals or apply protective coatings that block the electrochemical path.
The degradation process halts if the conductive liquid or the physical contact is removed from the joint. Sourcing specifications for pack components mandate specific material combinations and plating to prevent this decay.
Decay Mechanism
Dissimilar metals create a voltage potential when they are placed in contact, driving an electron flow from the anode to the cathode. In a battery pack, if moisture or salt spray penetrates the enclosure, it acts as an electrolyte that completes the circuit. The metal with the more negative potential, such as aluminum when connected to copper, acts as the sacrificial anode and begins to dissolve.
This reaction causes pitting and material thinning at the connection interface. As the contact resistance rises, the current pathway heats up during operation, creating thermal hotspots that can lead to cell degradation and eventual pack failure.
Prevention Strategy
Sourcing teams prevent these corrosion issues by specifying appropriate surface treatments and isolation materials for all joined metal components. Tin or nickel plating is applied to copper busbars to reduce the potential difference when they are bolted to aluminum terminals. Engineers also specify dielectric gaskets and sealing compounds that prevent moisture from reaching the critical contact areas.
Sourcing managers must audit suppliers to ensure that the plating thickness and quality meet the standards defined in the quality agreement, as thin or uneven coatings will fail prematurely under harsh operating conditions.
Supply Verification
Procurement contracts for connection hardware often include requirements for salt spray testing and environmental cycling to verify corrosion resistance. Sourcing professionals select suppliers that can provide certified test results showing that the joints maintain their low electrical resistance after exposure to humid, salty environments. This verification protects the battery pack from field failures in automotive or marine applications where moisture exposure is common.
By sourcing high-quality, corrosion-resistant components, companies ensure the long-term reliability of their battery packs, reducing the cost of warranty claims and enhancing customer satisfaction.
