this one should work:
sufficient capacity & power ratings..
also has two USB ports, you could charge your phone & field recorder or whatever at the same time.
haven't done the math myself, but a commenter writes:
This would correspond to 3,000mAh at 12v (37Wh/12v = 3.08Ah)
so, it should power the Digitakt for about 3 hours... hmm that's not a very long time.. maybe a larger battery would be better.
But, hell yeah.. field recorder + battery-powered Digitakt should be pretty good stuff!
disclaimer: I've never connected a battery to an Elektron device.