The electromotive force is the difference between the equilibrium electrode potentials of the two electrodes. Taking a lead-acid battery as an example, E=Ф+0-Ф-0+RT/F*In(αH2SO4/αH2O). (

HHR-210AB18F4)

Where: E-electromotive force

Ф+0--positive standard electrode potential, which is 1.690V

Ф-0--Negative standard electrode potential, which is -0.356V

R--general gas constant, which is 8.314

T--temperature, related to the temperature at which the battery is placed

F--Faraday constant, the value is 96485

αH2SO4--the activity of sulfuric acid, related to the concentration of sulfuric acid

αH2O--the activity of water, related to the concentration of sulfuric acid

As can be seen from the above formula, the standard electromotive force of the lead-acid battery is 1.690-(-0.0.356)=2.046V, so the nominal voltage of the battery is 2V. The electromotive force of a lead-acid battery is related to temperature and sulfuric acid concentration.