I’ll leave Tesla Motors cars out of this exercise since they are already using 700 Wh/L Panasonic NCA cells in their batteries.
I’m not a big fan of the NCA cells because of safety reasons, I would prefer that the current electric cars with limited range updated their batteries to second generation NMC cells. By second generation I mean the NMC cells with silicon added to the graphite anode, increasing their energy density. Amprius already sells this kind of batteries for smartphones and tablets that reach the mark of 700 Wh/L. Amprius is also a Nissan’s partner, so I expect that the second generation Nissan Leaf will use this technology.
Nissan Leaf’s old 24 kWh battery uses LMO cells made by AESC that have an energy density of 317 Wh/L. If Nissan changed to second generation NMC cells their batteries instead of 24 kWh would have 53 kWh. This could be done today if Nissan wanted to sell electric cars.
Yet, Nissan updated the LMO cells to NMC in the 30 kWh version of the MY 2016 Leaf. The EPA range increased 27% despite the battery capacity only increased 25%. Why? Because of the Ragone Curve.
This is the Ragone Curve of the old 24 kWh battery.
This shows that the efficiency of the battery drops when it is discharged faster. Lower discharge speeds means getting more Amps from the battery. This is why the Nissan Leaf with the 30 kWh is more efficient than the one with the 24 kWh, specially at highway speeds, despite of the new battery being 21 kg heavier than the old battery.
Meaning the Nissan Leaf could already have about 185 EPA mile range, or 298 km. With the battery pack size unchanged.
The Mitsubishi MiEV has a 16 kWh battery pack made with 88 GS Yuasa’s LEV50 cells. These cells have an energy density of 218 Wh/L. This means that if Mitsubishi updated its battery cells they could have a 51,4 kWh battery. The Ragone Curve is more severe in the GS Yuasa than the AESC cells used in the Nissan Leaf. Despite a increase in battery weight it could really improve its efficiency. The battery discharge capacity can vary 10 % depending on the speed it is discharged. The Mitsubishi could increase the MiEV EPA range from 62 miles to 199 miles (320 km).
So as you can see, the technology that already exists could make viable electric cars if automakers wanted to.
What is planned?
BMW only plan to use second generation NMC cells in 2019.
Too late, too little. One of the reasons may be that affordable electric cars with 200 miles range would hurt the sales of the upcomming plug-in hybrid cars. Those hybrids are announced everyday and costed huge resources to develop.