Fabrication of core–shell porous nanocubic Mn2O3@TiO2 as a high-performance anode for lithium ion batteries

A novel composite, porous cubic Mn2O3@TiO2, was fabricated via a simple and cost-effective approach and characterized in terms of structure and performance as an anode for lithium ion batteries. The porous Mn2O3 cubes were developed by calcining cubic MnCO3 particles without using any template and then coated with TiO2 from heat decomposition of tetrabutyl titanate. The characterization from FESEM, TEM, HRTEM, XPS, BET, and XRD indicates that the as-fabricated Mn2O3@TiO2 takes a hierarchically porous cubic morphology with an edge of ∼340 nm and a core–shell structure with porous cubic Mn2O3 as the core, which consists of nanoparticles of ∼30 nm, and a layer of porous single-crystalline spinel TiO2 as the shell, which consists of smaller nanoparticles of ∼5 nm. The charge–discharge tests demonstrate that this unique configuration endows the as-fabricated Mn2O3@TiO2 with superior charge–discharge performance, to be specific, a rate capacity of 263 mA h g−1 at 6000 mA g−1 compared to the 9.7 mA h g−1 of Mn2O3, and a cyclic capacity of 936 mA h g−1 after 100 cycles at 200 mA g−1 compared to the 443 mA h g−1 of Mn2O3. The nanosized particles of Mn2O3 and TiO2 and the hierarchically porous structure among them provide paths for lithium-ion diffusion and sites for lithium-ion intercalation/deintercalation, while the chemically and mechanically stable TiO2 ensures the structural stability of Mn2O3 cubes, yielding excellent rate capability and cyclic stability of the as-fabricated Mn2O3@TiO2 as an anode for lithium ion batteries.