Synthesis and electrochemical performance of Li2FeSiO4/C/carbon nanosphere composite cathode materials for lithium ion batteries

Abstract

Li2FeSiO4/C/carbon nanosphere (CNS) composites as cathode materials for lithium-ion batteries were synthesized by a simple hydro-chemical method. The double-carbon structural design of glucose pyrolysis-carbon (C) and CNS improved electrochemical performance of the composite where the CNS can build conductivity belts to connect the Li2FeSiO4/C particles and to favor electronic transmission. The exchange current density and the diffusion coefficient of lithium ions with the composite were 0.208mAcm−2 and 1.06E−11cm2S−1, respectively, which were much larger than that of conventional Li2FeSiO4/C composite cathode materials (i=0.131mAcm−2, DLi=4.69E−12cm2S−1). The electrochemical test results showed that the discharge capacity of 164.7mAhg−1 could be obtained, and especially, after 60cycles, 98.4% of the initial discharge capacity remained at 0.1C of galvanostatic discharge in the potential range of 1.5–4.8V (vs. Li/Li+). In addition, the discharge capacity of 92.4mAhg−1 at 5C was easily recovered to 159.8mAhg−1 at 0.1C.