General access to metal oxide (Metal = Mn, Co, Ni) double-layer nanospheres for application in lithium ion batteries and supercapacitors

- A series of metal oxide double layer nanospheres were prepared.
- The obtained materials show excellent performances in lithium ion batteries and supercapacitors.
- The unique structure of double layers is beneficial for superior electrochemical performances.

In this work, a series of metal oxide double-layer nanospheres (DLNs), such as Mn2O3, Co3O4, NiO, NiCo2O4, and MnCo2O4 have been successfully synthesized through a general template method. The layers of nanospheres were assembled by different nanostructure units and the removing of the SiO2 template formed a void of several ten nanometers between the double layers, resulting large specific surface areas for them. The energy storage performances of the as-prepared double-layer nanospheres were further investigated in lithium ion battery and supercapacitor systems. Based on their unique nanostructures, the double-layer nanospheres exhibit excellent electrochemical performance with long cycle stability and high specific capacities or capacitances. The best of these, DLNs-NiCo2O4 can deliver a reversible capacity of 1107 mAh g−1 at 0.25C after 200 cycles in lithium ion battery system, and shows a capacitance of 1088 F g−1 with capacitance loss of less than 3% at 5 A g−1 after 5000 cycles in supercapacitors.