LiNi_0.5Mn_1.5O₄ (LNMO)/poly(3,4-ethylenedioxythiophene) (PEDOT) composite cathode materials were prepared through in-situ polymerization of thiophene monomer (EDOT), with ammonium persulphate (APS) as oxidizing agent, p-toluenesulfonic acid (PTSA) as dopant. The morphology, amount of PEDOT coating, electrochemical properties of LNMO/PEDOT were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and galvanostatic charge and discharge tests. The results show that the composite materials show better cycle performance than bare LNMO.