Describe the theoretical principles of energy storage systems, focusing on concepts such as battery chemistry, charging and discharging processes, and energy conversion efficiency. Energy storage systems play a critical role in balancing supply and demand in electrical grids, supporting renewable energy integration, and providing backup power during outages. By understanding the electrochemical mechanisms that govern energy storage devices, engineers can optimize battery performance, extend cycle life, and develop innovative storage solutions for grid-scale applications, transportation, and consumer electronics.