Single‐, double‐, and triple‐shelled hollow spheres assembled by Co3O4 nanosheets are successfully synthesized through a novel method. The possible formation mechanism of these novel structures was investigated using powder X‐ray diffraction, scanning and transmission electron microscopies, Fourier transform IR, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. Both poly(vinylpyrrolidone) (PVP) soft templates and the formation of cobalt glycolate play key roles in the formation of these novel multishelled hollow structures. When tested as the anode material in lithium‐ion batteries (LIBs), these multishelled microspheres exhibit excellent cycling performance, good rate capacity, and enhanced lithium storage capacity. This superior cyclic stability and capacity result from the synergetic effect of small diffusion lengths in the nanosheet building blocks and sufficient void space to buffer the volume expansion. This facile strategy may be extended to synthesize other transition metal oxide materials with hollow multishelled micro‐/nanostrucutures, which may find application in sensors and catalysts due to their unique structural features.

Nd3+-sensitized quenching-shield sandwich-structured upconversion nanoparticles are reported, which exhibit highly efficient upconversion photoluminescence under excitation by an 800 nm continuous-wave laser. The transition-layer structure is essential to bridge energy transfer from the sensitizer to the activator and simultaneously block energy back-transfer from the activator to the sensitizer. These 800 nm-excited upconversion nanoparticles are a key step toward the development of upconversion nanophosphors for biological applications.