GM's Michigan battery plant (joint with LG) that makes the batteries for the Volt and the upcoming Bolt (according to the WSJ) has only the capacity to make batteries for 20,000 Bolts *or* 60,000 Volts, which means the initial production runs of the Bolt is likely significantly lower than 10,000 vehicles per year. If they want to make many more Bolts, they have to build about 5.5-6 gigawatt-hours of production capacity per 100,000 vehicles. Their current plant needs expansion just to hit a little more than 1 gigawatt.
The Tesla Gigafactory is expected to make 35 gigawatt-hours of cell production and combined with another 15 gigawatt-hours from Panasonic's factories, they represent a doubling of the world's lithium ion production from 2013. Until GM/LG or others announce, finance, and build plants of that size, they won't have the batteries in any large quantity.