Rational Construction of Multivoids-Assembled Hybrid Nanospheres Based on VPO₄ Encapsulated in Porous Carbon with Superior Lithium Storage Performance

The design of a new nanostructured anode material with high tap density while still keeping the common advantages of the hollow structure is a great challenge for future lithium-ion batteries (LIBs). Here, multivoids-assembled hierarchically meso-macroporous nanospheres based on VPO₄ encapsulated in porous carbon (MVHP-VPO₄@C NSs) were designed and fabricated. This unique structure can evidently decrease the excessive interior space in hollow spheres or multishelled hollow spheres to gain high volumetric energy density and at the same time can alleviate the large mechanical strain during the cycling process. As expected, MVHP-VPO₄@C NSs show good lithium storage behavior with gravimetric discharge capacity of 628 mAh g^-1 after 100 cycles at a current density of 100 mA g^-1. Furthermore, the full cell (LiFePO₄ cathode//MVHP-VPO₄@C NSs anode) also exhibits outstanding lithium storage performance. The insight obtained from this structure may provide guidance for the design of other electrode materials experiencing large volume variation during the lithiation-delithiation process.