Provided are spacers, ion-exchange devices comprising spacers, and methods of preparing spacers for improved fluid distribution and sealing throughout an ion-exchange device. These spacers can include an internal cavity surrounded by a perimeter of the spacer. The perimeter can have a first opening and a second opening within the perimeter, and the first opening and the second opening can be located on opposite sides of the internal cavity. The spacers can also have a first and second plurality of channels located within the perimeter, wherein each channel of the first and second plurality of channels extends from the internal cavity towards the first opening or the second opening.