The investigation on electrochemical reaction mechanism of CuF2 thin film with lithium

Crystalline CuF2 thin films were prepared by pulsed laser deposition under room temperature. The physical and electrochemical properties of the as-deposited thin films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic cycling and cyclic voltammetry (CV). Reversible capacity of 544 mAh g−1 was achieved in the potential range of 1.0-4.0 V. A reversible couple of redox peaks at 3.0 V and 3.7 V was firstly observed. By using ex situ XRD and TEM techniques, an insertion process followed by a fully conversion reaction to Cu and LiF was revealed in the lithium electrochemical reaction of CuF2 thin film electrode. The reversible insertion reaction above 2.8 V could provide a capacity of about 125 mAh g−1, which makes CuF2 a potential cathode material for rechargeable lithium batteries.