Differential (Incremental) Capacity Analysis (DCS & DCA) – Battery – Application Note 40

Abstract

This Application note is an extension of AN#2 that discusses the breadth of information that can be obtained via the PITT experiment. This note discusses how similar information can be obtained indirectly from a standard galvanostatic charge-discharge experiment. EC-lab software offers processing tools that allow extraction of dQ/dE vs. E (aka dQ/dV vs. V) data and analyzing the charge-discharge plots in the context of material phase transitions, and in particular solid solution vs. two-phase (or multi-phase), electrochemical mechanisms observed in battery materials.

Caution has to be exercised when drawing conclusions. A three-electrode cell is best suited for such experiments because in a two-electrode cell, phase phenomena occurring at both electrodes will interfere with each other and be compounded in a single graph.

Introduction

In recent years, lithium-ion batteries have received increased interest in battery development and investment. These batteries are widely used in portable electronic devices and show promise as an alternative technology to the Nickel Metal Hybrid battery commonly used in hybrid electric vehicle applications. The Li-ion battery technology offers a high voltage, high energy density, and long cycle life. However, like all rechargeable batteries, the use (charge and discharge) of these batteries leads to a degradation of its performance (battery capacity, structural stability, cycle life, and safety). In order to understand the degradation and the loss of capacity of Lithium-ion batteries, numerous studies were performed over the last decade [1-8]. These studies have linked battery degradation with mechanical, chemical or structural modifications of the electrodes material during the charge/discharge process.

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