A novel Cu+-doped Li[Fe0.9Cu0.1Li0.1]PO4/C cathode material with enhanced electrochemical properties

Abstract

LiFePO₄ is an effective battery material which has gained global focus. In this study, we prepared a novel Cu⁺-doped Li[Fe_0.9Cu_0.1Li_0.1]PO₄/C cathode material via a carbothermal reduction method using glucose as carbon source. X-ray diffraction (XRD) patterns and Rietveld refinement on the samples are consistent with the orthorhombic phase and showed that the substituting Cu⁺ ions and excess Li⁺ ions occupy the Fe sites. The micro-morphology of the samples indicates that Cu⁺ doping can decrease the particle size and maintain the crystal structure of LiFePO₄/C. XP spectra confirmed that the surface oxidation states of Fe and Cu are +2 and +1, respectively. The as-prepared Li[Fe_0.9Cu_0.1Li_0.1]PO₄/C composite exhibits enhanced initial discharge capacity (148.8 mA h g⁻¹) compared to the un-doped LiFePO₄/C. The discharge capacity remains at 149.8 mA h g⁻¹ after 50 cycles at a rate of 0.2C, which displayed an excellent cycling stability. Furthermore, the cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) results showed that the Cu⁺-doped LiFePO₄/C composite exhibits a higher lithium-ion diffusion coefficient and lower charge transfer resistance than the undoped counterparts. This study presents a novel Cu⁺-doped LiFePO₄/C cathode material with enhanced electrochemical properties, which could be potentially applied as a battery material.