A sealed and thermally-insulating fluid storage tank includes an angle arrangement placed at the intersection between the first and the second walls. The storage tank also includes a first and a second insulating blocks respectively retained on the first and second walls of the supporting structure and forming a corner of the thermally insulating barrier; and a metal angle structure forming a corner of the sealing membrane which is welded onto the plurality of metal plates of the first and second insulating blocks. Each of the first and second insulating blocks is associated with an adjacent insulating panel via a bridging element. Each of the first and second insulating blocks has at least one first and one second stress-relief slots extending respectively parallel and at right angles to the intersection between the first and the second walls.