Controllable Synthesis of Aluminium-Doped Limnpo4/C Cathode Materials With Stable Electrochemical Performance For Lithium-Ion Battery

Abstract

The Al3+ ion doped Li1-3xAlxMnPO4/C cathodes are prepared by a two-step synthetic method, the co-precipitation combined with hydrothermal routine, the doping effects on phase structure, surface morphology and electrochemical properties are studied. XRD patterns confirm that some tiny AlPO4 impurity generates in the synthesized aluminium-doped Li3PO4 precursors, after the hydrothermal process a single olivine-type phase Li1-3xAlxMnPO4/C  are prepared without impurity phase. SEM results show the concentration of Al3+ ion has some impacts on particle diameter, the porosity and agglomeration degree of the primary particles of aluminium-doped Li3PO4 precursors and LiMnPO4/C samples. Among all the samples, Li0.7Al0.1MnPO4/C sample delivers the maximum discharge capacity of 147.8 mAh/g (0.05 C) and 135.7 mAh/g (1 C) for the first cycle. At 0.05 C, the capacity loss is kept at 9.9% after 200 cycles. The analysis indicate that the electrochemical performance of LiMnPO4/C cathodes have been improved by doping a certain amount of aluminium ions.

Keywords: Lithium-ion batteries, Lithium manganese phosphate, Al3+ ion doping, Electrochemical property