A traction battery assembly includes a winged spacer assembly having a primary section extending in a first direction, and at least one wing section extending from the primary section in a second direction that is transverse to the first direction. A battery cell holding method includes constraining movement of a first battery cell in a first direction using a primary section of a spacer assembly. The first battery cell is within a first cell stack. The method further includes constraining movement of the first battery cell in a second direction using at least one wing section of the winged spacer assembly. The method still further includes constraining movement of a second battery cell in the first direction using the primary section of the winged spacer assembly. The second battery cell is within a second cell stack.