Conventional batteries, which typically use a liquid electrolyte, can suffer from undesirable chemical reactions that damage the battery's cathode. Replacing the liquid electrolyte with a solid ion conductor can improve battery stability and lifetime, and also allow a battery to be smaller because additional components aren't needed to maintain stability. Solid electrolytes are also compatible with a wider range of battery chemistries that could potentially offer higher power or storage density.
But solid-state batteries are expensive to make and have been difficult to scale up to the size needed for laptops or vehicles. Like other solid-state devices, solid-state batteries are normally made using complex, costly, vacuum-based deposition methods. The vacuum deposition limits the thickness of solid-state batteries, which, in turn, limits their energy storage capacity. So these thin-film batteries have been limited to use in small devices.