What do you call a device that consists of two or more electrochemical cells?

A device that consists of two or more electrochemical cells is known as a battery. Batteries are designed to store and convert chemical energy into electrical energy, allowing for the convenient use of power in various applications, from small electronics to electric vehicles. Each electrochemical cell within the battery generates a specific voltage, and when multiple cells are connected in series or parallel, the overall voltage or capacity of the battery can be increased, depending on the configuration.

In contrast, a capacitor is a device used to store electrical energy in an electric field, while a current source provides a constant current to a circuit irrespective of voltage changes. An inductor is a passive component that stores energy in a magnetic field when electrical current passes through it. Thus, the uniquely defined structure and function of a battery as a collection of electrochemical cells make it the correct choice for this question.