Improving the electrochemical properties of lithium iron(II) phosphate through surface modification with manganese ion(II) and reduced graphene oxide.

Lithium iron(II) phosphate (LiFePO) particles were simultaneously modified via reduced graphene oxide (rGO) and manganese ion(II) (Mn) through a facile one-step method. X-ray photoelectron spectroscopy unravels that the formation of Mn-O bond originated from Mn ion and fringe oxygen atoms of LiFePO, which is beneficial for the rate capability of cathode. As cathode for lithium-ion battery, the as-prepared rGO/Mn-LiFePO composite exhibits excellent electrochemical properties. Its discharge-specific capacity is 159 mAh g at 1 C after 800 cycles with capacity retention of 92%. Even at a high rate of 10 C, the rGO/Mn-LiFePO composite is still capable of delivering 140 mAh g of discharge-specific capacity, indicating its excellent rate capability and cycle stability. It was demonstrated that the simultaneous modification of Mn and rGO does not destroy the olivine structure of LiFePO, but it can stabilize the crystal structure, decrease the electrode polarization, enhance the electronic conductivity and Li diffusion coefficient, and thus improve its cycling and high-rate capability. [ABSTRACT FROM AUTHOR]