In situ measurements for shrinking/dilation in energy storage devices during cycling – Battery – Application Note 46

Abstract

In this application note, we report the charge-induced dilation of a Li-Ion battery measured by means of a dilatometer during a battery cycling experiment controlled by a Bio-Logic potentiostat/galvanostat.  The coupling of the dilatometer and the potentiostat/galvanostat allows the user to perform an in situ measurement during a battery cycling.

Introduction

As expected, many Li-ion battery materials expand during lithiation, and shrink during delithiation. LiCoO2 is a prominent exception from this rule. LiCoO2 consists of layers of monovalent lithium cations (Li+) that lie between extended anionic sheets of cobalt and oxygen atoms, arranged as edge-sharing octahedra. Lithium ions can be reversibly inserted into this structure in the potential range 3.0 to 4.3 V corresponding to x varying between 1 and about 0.5 in the formula LixCoO2, and the capacity varying between 0 and 140 mAh/g. In this reversible potential range, the interlayer distance along the c-axis continuously decreases during lithium insertion as has been shown by in situ XRD [1, 2]. At above 4.5 V, the lithium ions undergo an order disorder transition that is coupled to a change in the crystal lattice to a metastable (O1) state. This transition and as well the excessive SEI growth beginning already at 4.3 V are considered to induce a capacity fading at elevated potentials

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