Here's what I can tell you.

When I started college, I spent some time in a vehicle design program. In 1995, the golden rule was a thousand pounds of batteries had the energy density of a gallon of gasoline. This thing here has a 600cc Kawasaki motor, and a thousand pounds of Sonnenschein NiMH batteries that cost $80k.

If you had told me energy density of batteries would be up by a factor of seven in less than 20 years I wouldn't have believed you. It hadn't gone up by more than 50% since WWII. But at the time, a Motorola StarTac was state-of-the-art.

The Cell Phone revolution absolutely drove an improvement in battery design. You couldn't begin to run an iPhone on the battery in a StarTac - 230 minutes talk-time out of 500mAh. An iPhone 6 has an 1800mAh battery that gives it 14 hours of talk time and it's a much, much smaller phone. But here's the thing: in 1994 computers were profligate users of power. The original Dec Alpha chip dissipated enough heat to literally cook an egg (250W). Moore's Law was all about cramming cycles and energy in the smallest space possible... which flipped some time around 2003, 2004. People started caring a lot more about battery life than they did about horsepower because what we had in 2004 was pretty much good enough for most people. Ever since, the focus has been on more efficient chips as opposed to big skookum batteries. We've also kind of accepted the rise of the secondary battery pack; we carry outriggers for our phones now so that we can flatten the bejeesus out of them and still function.

The radical improvement we've seen in batteries over the past 20 years could continue. Using rough math, we need about 40x the energy density we have now... which is a long ways off. And if we got there, we'd be in a position for electric aircraft, electric helicopters, electric pogo sticks, electric everything before we'd hit the sweet spot for electric long-haul trucks. It just takes a shit-ton of juice to haul 40 tons of mail. That is probably something you aren't considering: those giant trucks you sweep by on the freeway weigh 20 times as much as your car, and an electric car is already a marvel.

It's easier with rail anyway. Lay down a cable and leave all the batteries back at the station... ;-)