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

Here is Why You Need An Adapter

The outlet and plug type used in Liberia are A, B, C and F and in Sierra Leone are D and G. This is how they look like.

Sierra Leone

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

Type D

Type G

Liberia

In Liberia, outlets of type A, B, C and F are in use.

Type A

Type B

Type C

Type F