Since they take so long to cook I was wondering if I could do something like cook them half the time one night and then finish cooking them the rest of the time in the morning or if there would be some problem with that.
It will be inconvenient, and you are likely to run into food safety problems. You would have to somehow make sure that they cool quickly enough after the first cook, and then heat up quickly enough for the second, and then cool again, that the total time in the danger zone is below 4 hours.
The more practical thing is to soak them before cooking. You can soak them overnight, for example. Then the total cooking time is much less, I don't have numbers in my head for kidney beans, but other beans are done in about an hour after a good soak. They are also a bit tastier that way (better hydrated) and it is an easy way to save energy.