Lithium-ion battery storage

technology

Electrochemical storage of electricity, and the second clear learning-curve technology in the energy system — but a storage technology, not a generation one, which changes what it can be asked to do. Volume-weighted average lithium-ion pack prices fell by roughly an order of magnitude across the 2010s on BloombergNEF's annual survey, reaching about 115 US dollars per kilowatt-hour in the 2024 edition after the largest single-year drop since 2017. The decline was driven by manufacturing scale, by cell chemistry shifting toward lithium iron phosphate — cheaper, cobalt-free and nickel-free, at the price of lower energy density — and by cathode material prices falling as the 2022 lithium spike unwound. Round-trip efficiency of a grid battery system is typically in the high eighties to low nineties of a per cent. The decisive property, however, is duration. Almost all utility-scale lithium-ion storage is built for one to four hours of discharge at rated power, because the cost of a battery scales with the energy stored while the revenue from arbitrage saturates: a four-hour system can move solar output from noon to the evening peak, and that is genuinely most of what a solar-heavy grid needs day to day. It cannot move energy from a windy October to a still January, and no amount of price decline turns a four-hour asset into a seasonal one.

A technology is not a place. Drawing it on a map would assert something about the world that no stored fact supports.