Gateway Energy Storage

Gateway Energy Storage is the world's biggest lithium-ion battery, operated by grid infrastructure developer LS Power. 
It has a storage capacity of 250 megawatts for one hour, and it is located in Otay Mesa, California, on the outskirts of San Diego. It uses cells from LG Chem.
The purpose of the battery is to provide power during times of peak demand after being charged with solar power during the day.