While Volta's invention wasn't exactly a "battery" as we know it today, his voltaic pile is considered the first electrochemical device capable of producing a continuous electric current. It consisted of alternating discs of zinc, copper, and cardboard soaked in salt water, creating a continuous flow of electricity.
While Volta's invention was groundbreaking, it was not a practical power source. It was bulky, inefficient, and quickly deteriorated. Further advancements were made by others to improve the design and functionality of wet-cell batteries.
