Nanostructured porous manganese carbonate spheres with capacitive effects on the high lithium storage capability

In this paper, nanostructured porous MnCO₃ spheres are facilely synthesized, which can simultaneously provide an increased surface for conversion reaction and capacitive storage as the anode material for lithium ion batteries. This material gives a superior specific capacity and excellent long-term cycling performance even at a high current density. It can deliver a stable capacity of 1049 mA h g^-1 after 200 cycles at a current density of 1000 mA g^-1, which is much higher than the theoretical capacity of 466 mA h g^-1. After 2000 cycles at a high current density of 5000 mA g^-1, a capacity of 510 mA h g^-1 can still be maintained. Their high rating performance at 5000 mA g^-1 is among the best-reported performances of anode materials. From the in situ or ex situ SEM observation, the porous MnCO₃ nanostructure can provide a stable template for reversible lithium insertion and extraction without significant morphology change and accommodate the volume change during the charge-discharge process. Also this structure increases the capacitive contribution to the total capacity compared with other MnCO₃ samples.