You started the project and he's not stepping up to the plate, which is what the 50/50 split of the rewards was based on. Commitment at this level is something that has to come from within, it's extremely unlikely there's anything you can do that will bring up his to anywhere close to 50%.
if you've found out quickly, consider yourself lucky. better than finding out a bit later.
whenever you get into a partnership/co-founding, you need to have the 'divorce' plan figured out and agreed upon ahead of time. good to have a vesting plan at the start to deal with this kind of thing...
You started the project and he's not stepping up to the plate, which is what the 50/50 split of the rewards was based on. Commitment at this level is something that has to come from within, it's extremely unlikely there's anything you can do that will bring up his to anywhere close to 50%.