I would like to know if it is possible to change the internal name of a document library using something like powershell?
The InternalName is immutable. It cannot be changed once it has been established.
If you have alternative of PowerShell then SharePoint Designer can do that.
See the same question asked by another user and refer answer which is marked as answer which uses SharePoint Designer for it.
In SharePoint Designer just navigate to All Files navigation node (not List and Libraries node), find your document library there -> right-click library -> rename.