Solid state batteries could be seen as everything we're looking for from an electric car battery, improving on all the fundamental characteristics needed for electric mobility.

Unfortunately, we probably won't be seeing them any time soon. The latest estimations reported by Automotive News (subscription required) are that solid state batteries will replace the current favorite, lithium-ion liquid batteries, between 2020 and 2025.

So what is a solid-state battery, and what makes it better?

Range, lightness and safety, in short. Energy in a solid state or "thin film" battery is stored, as the name suggests, in a thin, solid film. This is considerably lighter than a liquid electrolyte. As energy density is greater - up to 200 or 300 percent - more energy can be stored in the same space allowing a greater range without weight penalties.

Thin film is theoretically safer too. Lithium-ion cells have a risk of rupturing which could cause a fire. Carmakers are very careful to ensure their battery systems are entirely safe in current electric cars, but solid state is naturally safer.

For the manufacturers, solid state should be cheaper to produce too, as the batteries are less complex.

Though the battery technology hasn't been fully developed yet, both General Motors and Japanese conglomerate Itochu Corp. have invested $4.2 million in Sakti3 Inc of Ann Arbor, Michigan. Researchers at the University of Central Florida and Planar Energy, Florida are also working on the technology.

They're currently working around problems with the technology, but Scott Faris from Planar Energy believes it will eventually reduce the cost of battery technology by more than 50 percent.

Bill Wallace, director of global battery systems engineering at GM, thinks the technology could be in use in five years time (next-gen batteries always seem to be five years away...), but an estimation from consulting firm Auto Lectrification puts a longer 10-15 year timeframe on widespread use.

Either way, solid-state battery technology seems to be one of the most realistic ways of improving electric car range in the future - if liquid flow cells don't get there first.


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