A secondary energy storage battery, often referred to as a rechargeable battery, is designed to store electrical energy for reuse. They consist of various types, including lithium-ion, nickel-metal hydride, and lead-acid batteries, 3. Their function is to store energy for later use, enhancing efficiency and. Battery energy storage systems provide electricity to the power grid and offer a range of services to support electric power grids. Unlike primary batteries, which are designed for single-use and disposal after their energy is depleted, secondary batteries are engineered. These rechargeable energy storage devices are everywhere, from your wireless earbuds to grid-scale renewable energy systems.