A traction battery assembly for a vehicle includes an array of cells stacked on a tray. The array of cells defines opposing longitudinal sides and opposing lateral sides. First and second L-shaped components are attached to the tray. Each of the components includes an end wall and a sidewall that are integrally formed to define a substantially 90° corner. The first and second components are attached together such that each of the sidewalls is disposed adjacent one of the longitudinal sides and each of the end walls is disposed adjacent one of the lateral sides to form a housing around the tray that has an open top and an open bottom.