Construction of Co 3 O 4 three-dimensional mesoporous framework structures from zeolitic imidazolate framework-67 with enhanced lithium storage properties

High-porosity mesoporous framework structures are attractive for electrochemical energy storage and other applications. Herein we demonstrate a novel synthesis strategy to make zeolitic imidazolate framework-67 oxidize to a Co 3 O 4 three-dimensional mesoporous framework structure. This strategy relies on the oxygen-limitation effect of the closed nanocage and the affinity effect of polyvinylpyrrolidone towards zeolitic imidazolate framework-67. Several TiO 2 nanospheres, as the unique structure junctions, are uniformly embedded within the Co 3 O 4 framework to enhance the framework strength. The TiO 2 /hydrous titania polyhedron nanocage, as the protecting shell, further encapsulates the Co 3 O 4 framework, forming a perfect capsule-type hybrid. As anode materials for lithium-ion batteries, TiO 2 @Co 3 O 4 framework capsules show superior lithium storage performance with high reversible capacity, stable cycling life and good rate capability. A reversible capacity of 1042 mAh g −1 can be delivered after 200 cycles at a current density of 300 mA g −1 . The average discharge capacity over 200 cycles reaches 926 mAh g −1 . This demonstrates the superiority of this material structure and its great potential as an anode for high-performance lithium-ion batteries. This work indicates a new strategy to take advantage of metal-organic frameworks to synthesize their mesoporous framework derivatives.