I read the Toyota boards on Reddit from time to time.  I found this tonight.  I sure hope this is true and the solid state battery they are testing is ours.

See the quote below:

"Sweet-Sale-7303

People forget Toyota has hybrid cars that use batteries as well.  They also have solid state battery test cars driving around Japan.  People act like the RAV4 prime and Prius prime don't exist either.

New battery technology would allow the RAV4 prime to keep the battery size the same and add on range on just battery alone while still having the gas engine."