▎ 摘　　要

The effect of graphene (G) coated Si, Ti and Nb additions on the superconducting properties of MgB2 was systematically studied. The additives were prepared by a coating process and all introduced powders were scattered and combined with graphene. The coating process was useful for the uniform distribution of additives in MgB2 samples. The additives could effectively make the refinement of MgB2 grain size, which achieved an enhancement of surface pinning. Meanwhile, the densities of all the doped samples were larger than those of pure samples, which ensured a better intergrain connection for supercurrent. Therefore, the critical current density of MgB2 with 8 wt% G coated Nb addition got a significant enhancement due to the improvement of grain connectivity and flux pinning properties.