You Do Need power plug adapter while traveling from Balearic Islands to Sierra Leone.

Here is Why You Need An Adapter

The outlet and plug type used in Sierra Leone are D and G and in Balearic Islands are C and F. This is how they look like.

Balearic Islands

In Balearic Islands, outlets of type C and F are in use.

Type C

Type F

Sierra Leone

In Sierra Leone, outlets of type D and G are in use.

Type D

Type G