Electrochemical Battery Testing Methods Designed for Safety and Efficiency in a Research Laboratory
Authors: van Drunen Julia , Locati Corrado , Kubicsko Michael 
Published: February 2020

Electrochemical battery testing is performed under either potentiostatic or galvanostatic control and often results in the need to manage potentials on the order of tens of volts and currents higher than one ampere. The specifications of commercial potentiostat / galvanostat instruments (PGSTATS) vary according to the intended application. Some instruments are specifically designed for battery testing and handle high-power applications routinely. Other instrumentations are designed for broad application within an electrochemical research laboratory setting and may have standard specifications that just meet, or even fall short of, the needs for electrochemical battery testing. This contribution outlines some strategies to carry out popular electrochemical battery testing experiments safely and efficiently with an instrument intended for general laboratory purposes, such as the Metrohm Autolab PGSTAT302N, by using a few additional accessories and the Nova 2 electrochemical software package.
Characterization of lithium-ion (Li-ion) batteries typically involves galvanostatic charge and discharge over multiple cycles. A current booster is used to extend the usable current range of the PGSTAT from 2 amperes to 20 amperes. Nickel metal hydride batteries (NiMH) are also routinely characterized via charge and discharge cycling. Although a single NiMH battery may have a nominal voltage of 1.2 volts, these batteries are usually available in packs with multiple single cells. When characterizing a pack of batteries the total voltage can reach values greater than 10 volts, however the measureable potential range for the PGSTAT302N is ± 10 V. This contribution demonstrates how the potential range may be extended to ± 30 volt using a voltage multiplier, so that the instrument can be used for potentiostatic charge and discharge measurements on NiMH battery packs.
The galvanostatic and potentiostatic intermittent titration techniques (GITT and PITT) are popular methods applied to the characterization of Li-ion battery systems to determine the diffusion coefficient of lithium ions in the electrode active material. Herein, the GITT and PITT methods are demonstrated as applied to the characterization of a Li-ion battery with a nominal voltage of 3.75 volts. In this example, the current booster and voltage multiplier are not necessary.
Since battery testing applications may take a general purpose PGSTAT to the upper limit of its intended specifications, the safety of the researcher and the instrument must be considered in the experiment design. The potential and current limitations of the instrument are related to its power management capabilities. Exceeding the specifications can lead to permanent damage of the equipment, or subtle drifts in the measurement that result in unreliable data, depending on the magnitude of the overload. In addition, working outside of the battery’s own specifications could lead to heating, expansion, and possible explosion of the specimen, this being an unacceptable risk for the researcher. To this end, it is recommended to implement cutoffs on the maximum current, potential, and / or power associated with the electrochemical measurement. Such cutoffs are simple to program in the Nova 2 software. In this contribution, the use of cutoffs for safety and convenience is highlighted for the above-mentioned examples (charge / discharge, GITT, and PITT).