Ultrathin NiO/NiFe2O4 Nanoplates Decorated Graphene Nanosheets with Enhanced Lithium Storage Properties

• Ultrathin NiO/NiFe2O4 nanoplates derived from NiFe layered double hydroxides are fabricated on the graphene.
• NiO/NiFe2O4 nanoplates on the graphene show superior electrochemical performance compared to pure NiO/NiFe2O4 aggregates.
• The effects of the content and the particle size/component of NiO/NiFe2O4 on the electrochemical performances are studied.
• Graphene-encapsulated NiO/NiFe2O4 is prepared and shows slightly decreased performance compared to graphene-based composite.

As anode materials for lithium-ion batteries, bicomponent metal oxide composites show high reversible capacities; but the morphology and particle size of the composites are hardly controllable, which may reduce their electrochemical properties. In this work, ultrathin NiO/NiFe2O4 nanoplates with a diameter of 5 ∼ 7 nm and a thickness of ∼2 nm are controllably fabricated on the graphene derived from NiFe layered double hydroxides (NiFe-LDHs), and exhibit superior electrochemical performance compared to pure NiO/NiFe2O4 aggregates without graphene. The nanosized NiO and NiFe2O4 plates are separated from each other and the graphene substrate can prevent the aggregation of NiO/NiFe2O4 as well as enhance the electronic conductivity of the composite, which is beneficial to improving the electrochemical performance. Moreover, the effects of the content and the particle size/component of NiO/NiFe2O4 on the electrochemical performances are also studied in order to achieve optimal performance. Ultrathin NiO/NiFe2O4 nanoplates are further encapsulated by graphene nanosheets and show slightly decreased performance compared to those supported by graphene nanosheets. The different electrochemical behaviors of graphene-containing composites may be attributed to the different interactions between graphene nanosheets and NiO/NiFe2O4 nanoplates.

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