Improved electrochemical properties of LiFePO4/Cu cathode material synthesized via an optimized two-step chemical process

Abstract

LiFePO4/Cu (LFP/Cu) composite as a cathode material for lithium-ion battery was successfully synthesized via a two-step chemical process. The reductant concentration, solution pH, temperature and reaction time of this chemical process were investigated based on a series of experiments to explore the optimal parameters. The structural characteristics and electrochemical properties of LFP/Cu composite were compared with pure LiFePO4. X-ray diffraction (XRD) indicated that the obtained LFP/Cu composite was well crystallized, in addition, the copper particles did not destroy the olivine structure of LiFePO4. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) element map showed that nano-sized copper particles exhibited a homogeneous distribution on the surface of LiFePO4. Electrochemical impedance spectroscopy (EIS) compared the charge-transfer resistance (Rct) of LFP/Cu and pure LiFePO4 electrode, indicating that the decrease of Rct was nearly 40% after adding moderate amount of nano-sized copper particles. The charge–discharge tests demonstrated that the optimized LFP/Cu composite with 6.18% nano-sized copper particles delivered the initial discharge capacity of 146.7 mAh g−1 at 0.1 C, which was much higher than pure LiFePO4 and all the other samples. The better electrochemical properties were mainly attributed to the significantly decrease of Rct and the enhancement of electronic conductivity, which is benefit from the superficial nano-sized copper particles.