"Lithium-ion battery prices have sharply declined in recent years driven by steadily expanding manufacturing capacity, which has led to economies of scale and improved learning. That learning curve is expected to continue as battery companies are planning a six-fold manufacturing capacity increase by 2023.

Over the medium to longer term, Platts Analytics anticipates that mass-market electric vehicle adoption will continue to drive battery costs down despite concerns around raw material prices. Lithium-ion battery prices are expected to decline 40% by 2025, making it difficult for other technologies such as flow-batteries to compete, particularly for shorter durations." https://blogs.platts.com/2019/03/28/us-expansion-power-battery-storage/