Oxygen-deficient and orderly mesoporous cobalt oxide nanospheres for superior lithium storage

•3DOM Co3O4−X nanospheres were developed via a nanocasting method.•The 3DOM structure enhances mass transfer and restrains volume expansion.•The oxygen vacancies in Co3O4−X promote the electron and Li+ conductions.•The 3DOM Co3O4−X anode enables high-capacity and long-lasting lithium storage. 3DOM Co3O4−X nanospheres with abundant oxygen vacancies exhibit excellent cycling performance as anode materials in LIBs. [Display omitted] Lithium-ion batteries (LIBs) dominate the current electrical and electronic markets. However, the energy density that approaches the theoretical limit for conventional LIBs struggles to meet the future energy demand. Herein,5 oxygen-deficient cobalt oxide nanospheres in three-dimensional ordered mesoporous architecture (3DOM Co3O4−X) are developed via a simple nanocasting method, which serve as advanced anode materials for superior lithium storage. The unique highly porous and robust construction facilitates the mass transfer, restrains the volume expansion, and exposes vast interfaces for reversible lithiation/delithiation, while the oxygen vacancies in Co3O4−X lattice promote the electron/ion conductions and enrich the active sites for conversion reactions. Benefiting from these synergistic attributes, the 3DOM Co3O4−X electrodes retain a highly reversible capacity of 629.1 mA h g−1 after 1000 cycles at 2 A g−1, which significantly outperform the Co3O4 nanoparticle counterpart. This work demonstrates a highly promising material advancement combining architecture and defect engineering towards high-performance LIBs.