I want to render half of the frames and leave the other half for another time. Is this possible?
If you go to YouTube and put in seach terms of "blender 2.8" "image sequence", (use those quotes that way as two search terms), there are a bunch of vids that show how to create your movie from an image sequence, which is the best way to accomplish what you are trying.
I found that I still get a working video file from Blender, if I interupt a movie render, though, of course, it's incomplete. By restarting a new video render at the frame you left off, you could splice the two videos together using most video editing programs.
However, study the "image sequence" method. It's better. Less work, too. Just a whole lot of files. You can delete all those individual frame image files after you have your video created from the Video Editing step.