https://arstechnica.com/tech-policy/2020/09/the-story-of-cheaper-batteries-from-smartphones-to-teslas/

In 2010, a lithium-ion battery pack with 1 kWh of capacity—enough to power an electric car for three or four miles—cost more than $1,000. By 2019, the figure had fallen to $156, according to data compiled by BloombergNEF. That's a massive drop, and experts expect continued—though perhaps not as rapid—progress in the coming decade. Several forecasters project the average cost of a kilowatt-hour of lithium-ion battery capacity to fall below $100 by the mid-2020s.

That's the result of a virtuous circle where better, cheaper batteries expand the market, which in turn drives investments that produce further improvements in cost and performance. The trend is hugely significant because cheap batteries will be essential to shifting the world economy away from carbon-intensive energy sources like coal and gasoline.