The Electrolyzed Water Cell is a product of an Electrolyzer. To be created, the Electrolyzer needs to be directly in front of an energy storage block, such as the MFE or MFSU, but does not however need to be touching the output face.
If the energy storage block is over 70% full it will transfer some internal storage into the Electrolyzer by turning the regular water cells into Electrolyzed Water Cells. Making an electrolyzed cell takes 20,000 EU in all the energy storage blocks.
However, if the attached energy storage block falls below 25%, the Electrolyzed Water Cells are turned back into normal water cells and they will give 14,000-20,000 EU back in the process. More advanced energy storage blocks being much more efficient. They also stack up to 64 making them a good way of storing energy.