Constructing yolk-shell MnO@C nanodiscs through a carbothermal reduction process for highly stable lithium storage

Abstract

The application of MnO as anode material for lithium-ion batteries has been largely hindered by its unsatisfied rate capacity and short cycle life. To address this problem, yolk-shell MnO@C nanodiscs were successfully prepared through a novel carbothermal reduction approach. Polydopamine coated Zn0.5Mn0.5CO3 nanodiscs were annealed at 700 °C in Ar atmosphere, during which polydopamine-derived amorphous carbon was utilized to reduce Zn2+ to Zn0, leading to the evaporation of Zn. As a result, large void space between the MnO cores and carbon shells was formed, which could effectively accommodate the volume expansion of MnO during cycling. Benefited from the improved electronic conductivity by the uniform carbon shells, as well as the enhanced structural stability ensured by large void space, the yolk-shell MnO@C nanodiscs electrode exhibited a high reversible capacity of 910 mAh g−1 at 0.1 A g−1 and delivered a specific capacity of 605 mAh g−1 (with a capacity increase of only 11%) without noticable capacity fading after 600 cycles at a current density of 1 A g−1.