Polymer template-assisted microemulsion synthesis of large surface area, porous Li₂MnO₃ and its characterization as a positive electrode material of Li-ion cells

Lithium-rich manganese oxide (Li₂MnO₃) is prepared by reverse microemulsion method employing Pluronic acid (P123) as a soft template and studied as a positive electrode material. The as-prepared sample possesses good crystalline structure with a broadly distributed mesoporosity but low surface area. As expected, cyclic voltammetry and charge-discharge data indicate poor electrochemical activity. However, the sample gains surface area with narrowly distributed mesoporosity and also electrochemical activity after treating in 4 M H2SO4. A discharge capacity of about 160 mAh g-1 is obtained. When the acid-treated sample is heated at 300 °C, the resulting porous sample with a large surface area and dual porosity provides a discharge capacity of 240 mAh g-1. The rate capability study suggests that the sample provides about 150 mAh g-1 at a specific discharge current of 1.25 A g-1. Although the cycling stability is poor, the high rate capability is attributed to porous nature of the material.