Enhanced Electrochemical Properties of LiFePO₄/C Cathode Material by Metal Oxide Coating

Abstract

LiFePO4/C composite cathode material prepared by carbothermal reduction method was coated by metal oxide MnO2, Al2O3, CuO, respectively, by a chemical precipitation method. The effects of metal oxide coating on the structure and electrochemical performance of LiFePO4/C composites were systematically investigated. The structure and morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the electrochemical properties were evaluated by constant-current charge/discharge cycling tests. It is found that the coating of metal oxide could greatly improve its high-rate dischargeability and cycling performance. The LiFePO4/C cathode material coated by MnO2 exhibits a specific discharge capacity of 118.5 mAh/g at 3C rate, much higher than the uncoated sample (95.1 mAh/g), with a capacity degradation rate of only 6.3 % after 250 cycles at 3C rate.

The effect of phenol–formaldehyde resin on the electrochemical properties of carbon-coated LiFePO4 materials in pilot scale

“…Nevertheless, the bare LiFePO 4 shows to be an insulator with electrical conductivity of merely 10 −9 ∼10 −11 Scm −1 at room temperature [3,4], correspondingly leading to the low energy density and low ion mobility and consequently hinders the commercial application of LiFePO 4 . Numerous approaches have been applied to improve the electrical properties of LiFePO 4 cathode, including, minimizing the particle size of LiFePO 4 by sol-gel method [5,6], coreshell structure [7] doping the metal ions to the site of Li + [8], surfactant process [9], situ polymerization restriction method [10], as well as coating metal oxide [11,12] or carbons [13][14][15]. Coating conductive carbon, in which sucrose or glucose is generally chosen as the carbon source [14,15], is demonstrated to be much effective and thus a commonly used method to boost the electrical conductivity of LiFePO 4 .…”