Since 2019, the cost of wind and solar electricity production has been lower than that from fossil fuels, and costs are projected to continue falling well into the next decade. But for renewable energy to truly dominate the electricity market, it needs to be cheap and reliable, even when the sun is not shining and the wind is not blowing. That means the battery market needs to grow, too. So far, short-duration lithium batteries have dominated the market of grid-scale battery storage, but a re...