Sorry you're being downvoted. On the capacity front, I think your caution is very well founded. Since their commercial release 25 years ago, lithium ion batter

Sorry you're being downvoted. On the capacity front, I think your caution is very well founded. Since their commercial release 25 years ago, lithium ion batteries have only increased in energy density by like 2.5x. The vast improvement in battery life of electronics has come from the electronics, not from the batteries. And lithium ion is already near (within an order of magnitude) of its ultimate theoretical potential. Future progress here is going to get harder and harder. No battery expert I know expects future progress to be as fast as past progress. However, on the cost front, I think there's less reason to be pessimistic. Here the limit is more economics, and less physics. As the scale of production has risen, costs have fallen substantially over the past couple decades. And over the next few years, world lithium ion production is set to triple again with the Gigafactory and others coming online. How much cost savings this brings is uncertain, but there's no theoretical reason that greater automation and scale won't continue to push costs down. tl;dr: Non-chemists are too optimistic about technical progress in batteries. Future progress will almost certainly be slower. But there are no physical limits preventing prices from continuing to drop with experience and scale.