Lithium-ion (Li-ion) batteries store electricity through a reversible chemical reaction. The basic components are a container, electrodes, and an electrolyte. By loading the battery, the electricity is transformed into chemical energy, while during discharge, electrochemical reactions occur at the two electrodes generating a flow of electrons through an external circuit (DNV KEMA 2013). Li-ion batteries can be used for a variety of applications in large-scale energy storage such as frequency regulation, temporal storage and integrating renewables into the grid (making them more dispatchable). This factsheet focuses on power applications (<1 hour discharge time) such as power balancing and frequency regulation.