Nickel is commonly used as a lithium-ion battery lug because it has sufficient combination of electrical conductivity, solderability, strength, malleability and corrosion resistance, strength, malleability, solderability and corrosion resistance. However, as the number of individual cells in a pack increases, one problem with nickel is heat generation (especially in the bus bar), which reduces the efficiency of the cell and poses a risk of overheating.
Nickel’s limited thermal and electrical conductivity leads to several negative consequences. First, the high amperage contributes to Joule heating at the busbar and leads to an increase in cell temperature that can be detrimental to cell performance and life.
Damage to the performance and life of the battery. Second, the higher impedance of the connector material leads to more IR drop and therefore significantly lower voltage in the battery. Third, hot spots can occur due to insufficient thermal conductivity and poor thermal diffusion. Clad-metal connectors have electrical and thermal conductivity advantages to solve these problems, which are characterized below.
Characterization includes measurements of electrical conductivity, tensile properties, and formability. These measurements follow ASTM standards. Further characterization includes atmospheric corrosion testing, solderability testing, and solder testing. Corrosion testing is performed by exposure to corrosion immersion in ASTM 2570 water, followed by exposure in a condensing humidity chamber for 16 hours (100% relative humidity, 37.7°C), followed by drying for 8 hours.
ASTM D2570 water was composed of 148 mg sodium sulfate, 165 mg sodium chloride, and 138 mg sodium bicarbonate; dissolved in 1 liter of distilled or deionized water. Sixty cycles of testing were completed. WELDING SIMULATIONS Welding simulations were performed on selected cladding material systems at Amada Miyachi using a 300 ADP (Advanced Double Pulse) power source.
Welding techniques included the introduction of counter shunt slots and/or weld bumps on the cladding strips and the use of a stepped welding process when required.