Senior C&EN Correspondent Marc S. Reisch explains that solid-state batteries can improve the safety of lithium-ion batteries by replacing flammable liquid electrolytes with solids. Doing so can also give batteries greater energy density, thus allowing them a longer life. This boost could help car manufacturers eventually satisfy government mandates for emission-free alternatives to gas- and diesel-powered vehicles.  Toward this end, Toyota plans to put solid-state batteries in electric cars by 2022. And car manufacturers aren't the only ones paying attention to solid-state batteries. Apple, Dyson and Bosch are also investing in the technology.

Industry specialists are quick to point out, however, that the market for solid-state batteries is very small at the moment. And while some experts expect it to grow significantly in the next five to 10 years, others express doubts. The biggest impediment to widespread commercialization could be the price tag. Costs must drop dramatically before solid-state batteries can really challenge the reign of traditional lithium-ion batteries.