A wall-mounted battery is a proprietary battery design where the flat cells are linked side-by-side. The shape makes it possible to fix the batteries on the walls inside and outside buildings. The flat battery of 1cm – 2 cm thickness takes little internal space and makes the storage device an integral part of the building.
Originally the idea was applied to zinc-air batteries that required a gap between front-to-end connected cells to assure air flow to the air electrodes. The gaps decreased the volumetric energy densities of the zinc-air batteries substantially. When the cells were linked side-by-side the air had free access to the front air electrodes, and no gaps were required between the cells.
The nickel-zinc battery needs no space between cells; however, its flat design can bring many benefits. The nickel-zinc battery is a high-power energy storage device with a smaller energy density than that of the lithium battery. The smaller energy density leads to a larger volume. In the case of a flat design the difference is downplayed: the thickness of the nickel-zinc battery will be about 2 cm vs. about 1 cm for the same energy lithium power supply. This difference in thickness is not essential, but power capabilities, cost, safety and overall performance are expected to be appealing to the customer.