John Deere has made prototype electric tractors. The battery operated one was a ~100 (150?) horse power tractor packed full of batteries that was able to do everything the equivalent diesel tractor could do - for about 1 hour then the battery was dead. Note that the above tractor is considered mid size, the big tractors that sell the best have far more horse power. The other is a tractor with a 1km (or longer?) cable to it can plug into the grid at all times. Neither is practical for real farmers, though they do work.

I'm a Deere Employee. I cannot talk about projects other than the above, but I wouldn't hope for practical electric tractors in the near future.