Would it be a good idea to put lotion on skin that is peeling after sunburn?

Yes: Sunburn is a result of excessive oxidative stress to the tissues of your skin. Lotions that have antioxidant properties can partially reverse some of this damage. This is why coconut oil is so useful. The saturated fats in coconuts have anti-oxidant like effects.

Great Idea: Sunburn is response of the tissues to injury from solar radiation. It is simply inflammation which means increase blood flow to the area to promote healing. Do not use ice as this can injure already injured skin. Cool water soaks can help as can taking anti-inflammation medicines like Motrin or advil (ibuprofen). Avoid any further damage as this can cause scarring . Good skin cream applied daily/gently helps.