If you pry open one of today's ubiquitous high-tech devices-whether a cellphone, a laptop, or an electric car-you'll find that batteries take up most of the space inside. Indeed, the recent evolution of batteries has made it possible to pack ample power in small places.
solidstate batteries would be perfect indeed, but up to now I know of no solid electrolyte that can do the trick. The article itself does not mention any material beyond superionic lithium-ion conductors, but does not specify which one in particular. The premis seems to be "if it conducts fast enough, the battery can conduct efficiently"