Support structure for angled battery cell configuration for a traction battery assembly

A support structure is provided for a battery cell array which may include a pair of triangular prism shaped endplates having opposing parallel inner faces configured to exert a compression force on battery cells disposed therebetween and parallel outer faces not parallel with the inner faces. The support structure may also include a pair of opposing retention supports spanning between the endplates. The endplates and supports may be arranged such that the outer faces and supports define a rectangular prism. The inner faces may be oriented at an acute angle relative to at least one of the supports, and the acute angle may have a slippage angle value. Each retention support may define retention featured to orient battery cells and cell spacers such that the battery cells and spacers are parallel with the inner faces.