Simple synthesis of a double-shell hollow structured MnO2@TiO2 composite as an anode material for lithium ion batteries

Abstract

A double-shell hollow structured MnO₂@TiO₂ anode material has been successfully synthesized through a two-step template method. The monodispersed carbon spheres synthesized through a hydrothermal method act as the templates. The inner part of the carbon template acts as a sacrificial template to form the void and the outer part of it plays the role of self-template to synthesize hollow MnO₂ spheres. The composition, crystallinity, morphology, and valence state of the final product MnO₂@TiO₂ are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical performances of the double-shell hollow structured MnO₂@TiO₂ anode material have been comprehensively improved. The specific capacity of the composite retains 802 mA h g⁻¹ at the current rate of 200 mA g⁻¹ after 200 cycles, and it can still retain about 400 mA h g⁻¹ at a higher current rate of 1 A g⁻¹. Finally, a more detailed charging/discharging process of MnO₂ is proposed.