Facile synthesis of Li2MnSiO4/C/graphene composite with superior high-rate performances as cathode materials for Li-ion batteries

Abstract

In this paper, a Li2MnSiO4/carbon/graphene (LMS/C/G) composite is synthesized by a facile one-step synthesis method and shows superior high-rate performances as the cathode materials for lithium ion batteries (LIBs). In the LMS/C/G composite, carbon coated Li2MnSiO4 particles, with sizes of 20–30nm, are uniformly anchored on graphene nanosheets. When assembled as the cathodes of LIBs and charge–discharged at the high rates of 1C, 2C, 5C and 10C (1C=166mAg−1), the specific discharge capacities of the LMS/C/G composite can reach 210, 181, 143, and 109mAhg−1, respectively. These electrochemical performances are much better than the performances of the Li2MnSiO4 composites that simply coated with carbon (LMS/C) or merely wrapped by graphene sheets (LMS/G). Electrochemical impedance spectroscopy (EIS) analysis shows that, compared with composites LMS/G and LMS/C, composite LMS/C/G has smaller charge-transfer resistance through the solid-electrolyte interfaces and faster lithium ions diffusion coefficient in the cathode materials. These much improved electronic and ionic conductivities should account for the superior high-rate performances of the LMS/C/G composite.