Although a battery cell is an electrical storage system very much in terms of the thermodynamics, there is also a lot of cell mechanics. From the enclosure and it’s integrity, through the sealing system to the dynamics of the cell in a harsh environment.
Cell Enclosure
Aluminium 4680 Cell Can Structural Performance
The structural performance of aluminium 4680 cell cans made from two different materials namely Speira ION Cell 3-CB and Speira ION Cell 3-CS. The cell cans were produced by deep-drawing and wall-ironing featuring a wall-thickness of 0.75 mm. The can bottom features a thickness of 0.9 mm. The deep-drawing and wall-ironing route allows the application of high strength aluminium alloys and hard tempers.
Electrode Pressure and Expansion
The cell electrode pressure and expansion feels like two conflicting areas that have to be managed to enable performance over lifetime.
Sealing
The cell sealing is important as we don’t want to let any electrolyte escape and the cell operates at a pressure above atmospheric. Also, we need to ensure no water or other material passes into the cell, particularly important when designing a fully immersed dielectric cooling system.
Welding
Welding is the process of joining two pieces of metal together by hammering, pressure or fusion. Filler metal may or may not be used.
Weld Mechanical and Electrical Properties
The basic conclusion is that low electrical resistances were found to correlate with high mechanical strengths of the welds.
Hence pull strength test on cell tabs is often used as an indicator of a good weld.