Surfactant-assisted crystallization of porous Mn2O3 anode materials for Li-ion batteries

Abstract

MnCO₃ precursors with different morphologies were crystallized using three kinds of surfactants as soft templates, i.e., cation surfactant cetyl trimethyl ammonium bromide (CTAB), anion surfactant sodium dodecyl sulfate (SDS) and neutral poly(vinyl pyrrolidone) (PVP). When PVP was used, the reaction manner was changed from only stirring at room temperature to a hydrothermal route. Under hydrothermal conditions, different ethanol/water ratios and sources of CO₃²⁻ (NaHCO₃ and urea) were used. Porous cubic, regular spherical and nut-like spherical Mn₂O₃ samples can be obtained by a simple post-annealing process. The correlation between the morphology of Mn₂O₃ and its performance as an anode material for Li-ion batteries was evaluated. The nut-like spherical Mn₂O₃ sample has the best cycling performance, with a specific discharge capacity of 925 mA h g⁻¹ at a current density of 100 mA g⁻¹ after 180 cycles. The sample composed of cubes and spheres has superior rate performance. The specific discharge capacity decreases with increasing current density from ~872 mA h g⁻¹ at 100 mA g⁻¹ to ~361 mA h g⁻¹ at 2000 mA g⁻¹.