Porous lithium rich Li_1.2Mn_0.54Ni _0.22Fe_0.04O₂prepared by microemulsion route as a high capacity and high rate capability positive electrode material

A porous layered composite of Li₂MnO₃ and LiMn _0.35Ni_0.55Fe_0.1O₂ (composition:Li_1.2Mn_0.54Ni_0.22Fe _0.04O₂) is prepared by inverse microemulsion method and studied as a positive electrode material. The precursor is heated at several temperatures between 500 and 900 °C. The X-ray diffraction, scanning electron microscopy, and transmission electron microscopy studies suggested that well crystalline sub-micronsized particles are obtained. The product samples possess mesoporosity with broadly distributed pores around 10∼50 nm diameter. Pore volume and surface area decrease by increasing the temperature of preparation. However, the electrochemical activity of the composite samples increases with an increase in temperature. The discharge capacity values of the samples prepared at 900°C are about 186 mAh g^-1 at a specific current of 25 mA g^-1 with an excellent cycling stability. The composite sample also possesses high rate capability. The high rate capability is attributed to the porous nature of the material.