In Situ Measurements of the Thickness Changes for a Lithium Rechargeable Cell Based on a V 6 O 13 Composite Electrode during Lithium Insertion and Extraction

Abstract

An in situ technique utilizing a linear voltage displacement transducer device for investigating the thickness changes occurring during the cycling of a lithium insertion type rechargeable cell based on a composite cathode is described. We believe the method is generally applicable to other battery systems which undergo expansion/contraction effects during normal operation. During cell discharge there is a gradual decrease in cell thickness, while the converse is true during the subsequent charging process. The thickness changes are highly reversible over the single cycle considered. The variation of cell thickness was approximately linear with depth of discharge. For the cell in the fully discharged state, the overall thickness change of the active cell components was ∼6%. When the thickness variation associated with the lithium electrode is excluded from the calculations, the cathode increases in thickness during cell discharge and decreases during cell charge. The changes are consistent with the literature‐reported cathode unit cell expansion/contraction effects caused by the lithium insertion/extraction processes.