Confinement of PMo12 in hollow SiO2-PMo12@rGO nanospheres for high-performance lithium storage

Abstract

To meet the ever-increasing demand for energy storage in social development, high energy density battery materials are required. Herein, we successfully designed a novel hollow SiO₂-PMo₁₂@rGO nanosphere via electrostatic interaction (PMo₁₂ is H₃PMo₁₂O₄₀; rGO is reduced graphene oxide). The PMo₁₂ clusters were electrostatically attached onto the surface of the hollow SiO₂ spheres with amino terminals, and the rGO layer was further externally wrapped on the composites to confine the POM clusters. The hollow SiO₂-PMo₁₂@rGO nanocomposite was used as an anode material for lithium-ion batteries (LIBs). It showed an overall reversible capacity of 720 mA h g⁻¹ for 100 cycles at a current density of 100 mA g⁻¹, which was twice as large as that of the hollow SiO₂@rGO and SiO₂-PMo₁₂ composites. The hollow structure of the composites provided abundant void space to buffer the volume changes during the lithiation and delithiation processes. Confinement of PMo₁₂ with the rGO layer prevented the POM clusters from dissolution in the electrolyte, improved the migration of Li⁺ and enhanced the conductivity of the entire material. The superior performance of the hollow SiO₂-PMo₁₂@rGO nanosphere mainly resulted from the synergistic effects from the three components.