Solid-state batteries are an emerging alternative to conventional lithium-ion cells. In a conventional lithium-ion battery, ions shuttle between the cathode and anode through a flammable organic-solvent electrolyte. In solid-state designs, the anode, cathode and electrolyte are compressed together as slabs, which allows more conductive material per unit volume and reduces combustion risk. Their energy densities can reach 500 watt-hours per kilogram (Wh/kg), compared with about 300Wh/kg for liquid electrolytes.
The main barrier to scaling is brittleness: as ions repeatedly embed in electrode material, the battery expands and contracts, creating voids that crack and degrade performance. In January 2026 researchers at the Shenzhen Institutes of Advanced Technology, part of the Chinese Academy of Sciences, made an electrolyte by alternately stacking layers of ceramic 1-100nm thick with similarly thin polymer sheets—a "layer-cake" sitting on its side. A March 2026 paper led by MIT researchers concluded that dendrites (wiry crystals that cause short circuits) grow when chemical reactions weaken the electrode, not from excess lithium accumulation as previously thought. A team at Oak Ridge National Laboratory found a way of adding zwitterions to polymer segments to allow ions to travel up to 10bn times faster.
Solid electrolytes open the door to materials other than lithium. Sodium is cheaper, more stable and 1,000 times more abundant in Earth's crust than lithium, but sodium atoms are bigger and heavier, making them unlikely to embed in conventional graphite electrodes. A solid electrolyte allows anodes to be made of highly reactive sodium metal (density up to 500Wh/kg, vs about 175Wh/kg for hard carbon). Some designs remove the anode altogether—sodium ions accumulate on a current collector during charging, effectively creating the anode during operation.
"Dry electrode manufacturing"—pressing dry powders together to form solid batteries—cuts energy use by about half and manufacturing costs by about a fifth, while boosting performance. CATL, the world's largest battery manufacturer, has said it will produce solid-state batteries by 2027 and plans to launch the first sodium-ion EV by mid-2026. Samsung and Toyota have pledged mass production by 2027. Ford launched a battery-making unit in May 2026, planning large-scale batteries for data centres and industrial businesses by 2027. About 30% of cars sold in 2026 are expected to be EVs.
It isn't an optical illusion. It just looks like one.