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GITT – Electrochemistry & Battery Application Note 1

Latest updated: May 6, 2020

Abstract

This document discusses how galvanostatic cycling with potential limitation (GCPL) can be applied to both classical cycling (charge-discharge cycles, often referred to as CCCV or CC-CV) of batteries, as well as to Galvanostatic Intermittent Titration Technique (GITT) that provides insights about the extent of polarization (voltage losses). If battery materials are studied in three-electrode cells with a stable reference (for example Li metal for Li-ion cells), using the unique feature of Bio-Logic potentiostats-galvanostats-ZRAs, namely a second electrometer for studying simultaneously the Working and the Counter electrode, exact sources of polarization can be identified, as well as which electrode is limiting the cell capacity and/or power performance.

 

Introduction

The basic characteristic of an electroactive intercalation compound is the thermo-dynamic voltage-composition relation, which corresponds to the equilibrium phase diagram of the system. See for example Armand [1] for a detailed description of the various behaviors that can be encountered, depending on the changes in electronic and structural properties upon intercalation/deintercalation.

In short, continuous dependence of the potential vs. composition corresponds to a solid-solution single-phase domain, whereas a potential plateau corresponds to a two-phase domain.

Other properties of interest, particularly with regards to possible applications for active electrodes in a battery are the potential window of electrochemical stability, kinetics, and reversibility of the intercalation process.

The voltage-composition relation can be determined either in a current-controlled mode or in a potential-controlled mode. These two techniques are usually referred to as “Galvanostatic Intermittent Titration Techni-ques” [2] and “Potentiostatic Intermittent Titration Techniques” [3], respectively.

 

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