Wonderbar:

Fascinating, thank you. As I understand it, if batteries improve less than 5% per year, we should not see significant weight improvement for at least five or 10 more years.

Don’t forget that cells are only one part of the battery pack.  As energy densities increase thermo control and crash protection become even more important.  Under current technologies, a 100 kWh battery has the energy equivalence of approximately 11.4 liters of petrol and weighs about 8.2 kilograms.  The fuel storage and delivery system weighs about the same. The corresponding battery pack in a Tesla, Audi, or Porsche weighs from 550 to 680 kilograms.  

Some argue that an internal combustion engine has 1/3 the energy efficiency of an EV so the petrol consumed is 3 times greater or 24 kilograms. Again, the energy delivery system for a petrol fuel vehicle weighs 20 times less than the current electrical storage systems.  Rerun the calculations, if an ICE system becomes more efficient.  The Atkinson cycle ICE used in a Toyota Prius is said obtain 40% efficiency and the Mahle Jet ignition system used on Ferrari’s F1 car is over 50% efficient.  These advances mean, absent regulations, ICEs can remain economically attractive for decades.