"CEO for Panasonic North America Tom Gebhardt said in an interview that solid-state batteries for electric vehicles are at least a decade out for mass-market electric vehicles.

Known commonly as solid-state batteries, solid-electrolyte batteries are believed to be the next major step in battery technology. They offer superior safety to liquid-electrolyte batteries because of their lesser chance of a fire when their cases are punctured, and offer better energy density, which could translate into smaller, lighter batteries.

Gebhardt told Business Insider that like all technologies, the industry loves to hype up the next major development in the battery field, no matter how far out. He expects current lithium-ion battery technology to undergo gradual refinement, improving energy density, charge rate, safety, and cost-effectiveness."

TheDrive

I tend to agree with what he says, we have first gen solid state batteries, but to make them in the density and quantity needed is a bit out. I expect most if not all EVs that come out between now and 2024 will be Lithium Ion and then by 2024 we will see some of the top line models have the solid state and by 2030, we will see solid state push into pretty much all autolines for EV use.

The benefits of Solid state batteries will I think help OEMs to push to move to them sooner rather than later.

At this point the transition to EV is coming regardless of how people feel about it, it is going to be thrive or die for carmakers in the new market. 

Solid Electrolyte Batteries -- most commonly manifested as Lithium-Polymer batteries are generally unsuitable for automotive applications because they have a low current rating and high internal resistance. They also have lower recharge cycle endurance, but that is secondary.

The common method of alleviating the limitations of Lithium-Polymer cells is typically the introduction of liquid or gelled electrolyte to supplement the solid (film) electrolyte. But, this negates the advantages of true Li-Po designs, namely that it does not need to be a pressure vessel and it can be made in all manner of shapes. Liquids and gels, you see, can go gaseous and cause a cell to blow up like Lithium-Ion batteries.

There are liquid electrolyte chemistries that are inherently safe (eg. Lithium-Iron-Phosphate) and proof from thermal runaway. LiFePO4 also has notably better cycle endurance. Its volumetric energy density is pretty good (about 83% as good as Lithium Cobalt Oxide) but it is heavy with a gravimetric density of only oabout 37% as good. For cars, it is simply heavier... the same capacity LiPO4 will fit in about the same space or perhaps a tad bit less space (once you dump the cooling paraphernalia), but it'll weigh 2.5 times as much.