伏打电堆中的电化学反应

The operation of the Voltaic pile is governed by the principles of electrochemistry. Each metal has a different electrode potential, or tendency to lose electrons. Zinc is more reactive than copper, meaning it has a more negative electrode potential and is more easily oxidized. This difference in potential is what drives the flow of electrons from the zinc (anode) to the copper (cathode) through an external wire. The electrolyte’s role is crucial; it contains ions that can move between the electrodes to balance the charge, completing the electrical circuit. In a simple brine (NaCl) or acid (H2SO4) electrolyte, water molecules provide the hydrogen ions (H+) for the reaction at the cathode.

The overall reaction for a pile using a sulfuric acid electrolyte is [latex]Zn + 2H^{+} \rightarrow Zn^{2+} + H_2[/latex]. The copper itself does not chemically react; it serves as a noble, conductive surface for the reduction of hydrogen ions. The potential of a single zinc-copper cell is approximately 0.76 volts, though this can vary with the electrolyte concentration and temperature. This fundamental mechanism of converting stored chemical energy into electrical energy is the basis for all modern batteries, albeit with different materials and more sophisticated designs to improve efficiency and longevity.