The charge for energy storage varies significantly based on several key factors, including 1. In this work we describe the development of cost and performance projections for utility-scale lithium-ion battery systems, with a focus on 4-hour duration systems. The projections are developed from an analysis of recent publications that include utility-scale storage costs. The suite of. Electrical Energy Storage (EES) systems store electricity and convert it back to electrical energy when needed. The first battery, Volta's cell, was developed in 1800.