General Motors is investigating a new way to shape prismatic battery cells to improve cooling properties.
A patent filing from the automaker published by the United States Patent and Trademark Office (USPTO), dated Dec. 26, 2024 but first posted by GM Jun. 23, 2023, details stacking of layers in an inverted “U” shapeas opposed to the folded or stacked layers used in current prismatic cells.
This format creates a high thermal conductivity in the horizontal direction in the upper part of the cell for better heat dissipation, and in the vertical direction near the bottom of the cell, which can increasing the efficiency of cooling systems if they are included in the package, GM claims.
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The inverted “U” stack also increases the thermal delay time within the cell, causing the heat to spread more slowly, depending on the fill. Even if the cell overheats, the peak temperature should thus remain low and the energy contained, GM claims, adding that this allows a 50% smaller thermal response barrier.
That may be in future cell designs to help reduce cell size, or increase energy density by pressing active substances into that space. And for maximum benefit, the packet size can also be small because of those reduced cooling requirements.
But the cell format proposed here is also a very complex situation that can present manufacturing challenges, which may explain why major battery manufacturers have not tried it so far.
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GM already appears to be on track to use cell, cylindrical, and prismatic cell formats, all at once, in its production EVs, and that flexibility is being emphasized. It also looks at some of the odd cell shapes in previously filed patents, and with an eye toward improved cooling.
Tesla, Lucid, and Rivian all chose to emphasize cylindrical cells—with obvious advantages in size and efficiency. BMW will also use cylindrical cells in its next-generation Neue Klasse EVs, the first of which has just been put into production ahead of a scheduled debut in 2025, with promises of a big increase in power.