Incremental Capacity and Voltammetry of Batteries, and Implications for
Electrochemical Impedance Spectroscopy
Abstract
Incremental capacity analysis (ICA), where incremental charge (Q)
movements associated with changes in potential are tracked, and cyclic
voltammetry (CV), where current response to a linear voltage sweep is
recorded, are used to investigate the properties of electrochemical
systems. Electrochemical impedance spectroscopy (EIS), on the other
hand, is a powerful, non-destructive technique that can be used to
determine small-signal AC impedance over a wide frequency range. It is
frequently used to design battery equivalent-circuit models. This
manuscript explores the relationships between ICA, CV and EIS and
demonstrates how sweep rate in CV is related to charging (C) rate in
ICA. In addition, it shows the connection between observations linked to
rate of charge movement in CV and ICA and intermittent, irregular
behavior seen in EIS when performed on a battery. It also explains the
use of an additional DC stimulus during EIS to ensure reliability of
battery impedance data and to facilitate equivalent-circuit modeling,
and suggests a method for obtaining CV-type data from a whole battery
without risking its destruction.