[5e] How to handle rewarding diplomatic endings to a battle?

So me and my husband have been playing 5e for the first time with him playing and me as DM. So after playing a couple sessions, I realize that his play style is to befriend enemies or try to find peaceful resolutions after feeling bad for the enemies. I've started introducing enemies that can't be reasoned with, but I also want to be able to reward when he comes up with creative ending to what would normally be a battle. By this I mean experience. How would yall reward this? I know you normally only give it for defeating an enemy, but I don't want his character stunted because he enjoys playing a certain way. Thoughts?

Also I did try looking it up but couldn't find the right combo of words that would give me the answer to this. Which is why I just made my own post, don't intend to be lazy or redundant by posting this!