A potentiostat performs 2 or 4 wire tests to measure a cell’s currents depending on the applied voltage potential. The basis of Ohm’s Law provides a calculated value of impedance at these different current values. With the results from the potentiostat, users can then plot an I-V curve and calculate the resistance of the cell.
Potentiostats can also perform analysis through Electrochemical Impedance Spectroscopy (EIS). Data from the EIS is plotted in a Bode plot or Nyquist plot to display certain characteristics over a frequency range. EIS testing allows us to find electrochemical corrosion in items ranging from batteries to concrete and even medical implants. Battery testing through EIS is beneficial because it’s a non-destructive method of analyzing a battery’s characteristics, like the expected lifespan or State of Charge (SoC).
Most modern potentiostats are also implemented with a galvanostat. These offer the variable currents applied while measuring voltage potential. A galvanostat can also acquire data through EIS testing, offering results similar to an impedance analyzer. But, while potentiostats are often used to find corrosion in high impedance systems, a galvanostat is best for battery testing with low internal resistance.