Transition Metal (Fe, Co, Mn) Boosting the Lithium Storage of the Multishelled NiO Anode

Further commercial application of low-cost NiO-based anodes is hindered by their large volume expansion after full lithiation and relatively poor theoretical capacity. To improve these issues, transition metal (Fe, Co, or Mn)-modified triple-shelled NiO microspheres (TS-NiO) are successfully synthesized by using a hard template double-adsorption method. Among them, the Fe-modified TS-NiO (TS-NFO) exhibits an extraordinary lithium storage ability with high reversible capacity and outstanding cycling stability (2061.1 mAh g(-1) after 800 cycles at 0.5 A g(-1)), which is the highest performing nickel oxide-based anode reported to date. The outstanding electrochemical performance of TS-NFO can be ascribed to its unique triple-shelled structure. The inner core of TS-NFO is composed of NiO and is encapsulated by two outer shells which are composed of a mixture of alpha-Fe2O3 and NiFe2O4, resulting in a unique hollow triple-shelled structure (NiO@alpha-Fe2O3/NiFe2O4). The void space between the triple shells leaves room for their volume changes during lithiation/delithiation, which improves the cycling stability. In addition, the introduced alpha-Fe2O3/NiFe2O4 outer shells increase the energy density and reversible capacity due to a synergistically interactive effect.