You Do Need power plug adapter while traveling from Cape Verde to Niger.

Here is Why You Need An Adapter

The outlet and plug type used in Niger are C, D, E and F and in Cape Verde are C and F. This is how they look like.

Cape Verde

In Cape Verde, outlets of type C and F are in use.

Type C

Type F

Niger

In Niger, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F