Superior lithium-ion insertion/extraction properties of a novel LiFePO4/C/graphene material used as a cathode in aqueous solution

Abstract

Herein, olivine LiFePO₄ covered with graphene and carbon layers is prepared via a sol–gel method, followed by calcination, and the resultant composite is used as a cathode material in aqueous rechargeable lithium-ion batteries (ARLBs). The phase structure and morphology of the composite are characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and specific surface area analysis (BET). The ARLB system is fabricated using LiFePO₄/C/graphene as the cathode and a zinc anode in 1 mol L⁻¹ ZnSO₄·7H₂O and saturated LiNO₃ aqueous solution without dissolved oxygen, which delivers a capacity of 153 mA h g⁻¹ at 0.5C rate. Even at a 50C rate, it maintains a capacity of 95 mA h g⁻¹ after 200 cycles. The excellent rate capabilities show that this cathode material exhibits good electrochemical performance and this novel ARLB has great potential in the fields of energy storage and high power sources.