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How does a battery maintain a steady current in an electric circuit?

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A battery maintains a steady current in an electric circuit by acting as a source of electromotive force (emf). Despite its name, emf is not a force but the energy per unit electric charge imparted by the device to drive charges around a circuit.1

To sustain a constant potential difference between its terminals, a battery must continuously replenish the excess positive and negative charges that are depleted as current flows. It achieves this by performing work to transport these charges internally from one terminal to the other, moving them in a direction opposite to the electric force that would otherwise push them back.2

In a chemical battery, this process is powered by chemical reactions that release energy due to differences in electron binding between materials, such as copper and zinc. By physically separating these reactions, the battery forces electrons to travel through the external circuit to complete the path, thereby generating a steady flow of electricity.23