How does an Element based Chakra release work
It's easy, the Raikages use the Lightning Release as a cloak to increase their physical prowess when using Taijutsu or using any movements.

While Sasuke uses Lightning Release technique like Chidori to attack himself to disintegrate C0 bomb that already inside his body. When using chidori, chidori's lightning only happen outside the body, not inside. In order to disintegrate C0 bomb, Sasuke must channel his chidori's lightning to all of his body including inside body. Even though Sasuke able to use Lightning cloak chakra mode, it also happens only outside the body, not inside. So Sasuke must attack himself with chidori to channel the lightning to all over his bodies.