A battery is an electrochemical energy storage device, whether it’s a single cell or a group of cells connected together. When multiple cells are combined in series or parallel, they form a battery pack with higher voltage and / or capacity. Batteries can be primary (single-use) or secondary (rechargeable) systems. Today, lithium-ion batteries dominate rechargeable applications due to their high energy density and efficiency. The term “battery” has become synonymous with the power source in devices ranging from smartphones and laptops to electric vehicles and grid storage systems.
