The following submission statement was provided by /u/redingerforcongress:

The battery pack will be based on GM's Ultium platform, which it's using to power its own electric vehicles. Due to the type of battery cells it employs, Ultium is billed as a modular and scalable system that can be adapted to different needs, so it may just fit the bill for the military.

GM said the military wants a light- to heavy-duty EV for use in garrison and operational environments in order to reduce fossil fuel use. As a result, that should reduce the military's carbon emissions.

Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/yfbyck/gm_will_make_an_ultium_battery_pack_prototype_for/iu2s5df/