LiFe1-XMgXPO4/C as cathode materials for lithium-ion batteries

Abstract A cathode nanomaterial LiFe 0.8 Mg 0.2 PO 4 with olivine structure was synthesized by the sol-gel method and studied using X-ray diffraction analysis, scanning electron microscopy, Mossbauer spectroscopy and electrochemical testing under the operating conditions of a lithium-ion battery. It is demonstrated that the iron substitution with magnesium occurs in the studied material. Discharge capacity of LiFe 0.8 Mg 0.2 PO 4 /С is 127 mAh g −1 at a current of 20 mA g −1 and is close to the theoretical value for the considered composition. It is determined utilizing Mossbauer spectroscopy that at the early stage of the LiFe 0.8 Mg 0.2 PO 4 charging process nanoscale regions are formed, having a FePO 4 structure and an enhanced solubility of divalent iron ions.