Pulsed Laser Deposition and Electrochemical Characterization of LiFePO4–Ag Composite Thin Films

Abstract

AbstractA simple approach is proposed to enhance the electrical conductivity of olivine‐structured LiFePO4 thin films by uniformly dispersing small fractions of highly conductive silver (ca. 1.37 wt %) throughout the LiFePO4 film. In this approach, a highly densified (>85 %) LiFePO4–Ag target was first fabricated by coating conductive silver nanoparticles onto the surfaces of hydrothermally synthesized LiFePO4 ultrafine particles by a soft chemical route. Pulsed laser deposition (PLD) was then employed to deposit LiFePO4–Ag composite thin films on the Si/SiO2/Ti/Pt substrates. The PLD experimental parameters were optimized to obtain well‐crystallized and olivine‐phase pure LiFePO4–Ag composite thin films with smooth surfaces and homogeneous thicknesses. X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectrometry (Raman), X‐ray photoelectron spectroscopy (XPS), DC conductivity measurements, cyclic voltammetry(CV), as well as galvanostatic measurements were employed to characterize the as‐obtained LiFePO4–Ag composite films. The results revealed that after silver incorporation, the olivine LiFePO4 film cathode shows a superior electrochemical performance with a good combination of moderate specific capacity, stable cycling, and most importantly, a remarkable tolerance against high rates and over‐charging and ‐discharging.