Wang L, Yuan Y F, Chen Q, Zheng Y Q, Yin S M, Guo S Y
College of Machinery and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, People's Republic of China.
Nanotechnology. 2019 Oct 25;30(43):435402. doi: 10.1088/1361-6528/ab31ec. Epub 2019 Jul 13.
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 CoO 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 nanospheres, as the unique structure junctions, are uniformly embedded within the CoO framework to enhance the framework strength. The TiO/hydrous titania polyhedron nanocage, as the protecting shell, further encapsulates the CoO framework, forming a perfect capsule-type hybrid. As anode materials for lithium-ion batteries, TiO@CoO 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 can be delivered after 200 cycles at a current density of 300 mA g. The average discharge capacity over 200 cycles reaches 926 mAh g. 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.
高孔隙率介孔骨架结构在电化学储能及其他应用领域具有吸引力。在此，我们展示了一种新颖的合成策略，可使沸石咪唑酯骨架结构-67氧化为CoO三维介孔骨架结构。该策略依赖于封闭纳米笼的氧限制效应以及聚乙烯吡咯烷酮对沸石咪唑酯骨架结构-67的亲和效应。几个TiO纳米球作为独特的结构连接点，均匀地嵌入CoO骨架内以增强骨架强度。TiO/水合二氧化钛多面体纳米笼作为保护壳，进一步包裹CoO骨架，形成完美的胶囊型杂化物。作为锂离子电池的负极材料，TiO@CoO骨架胶囊表现出优异的储锂性能，具有高可逆容量、稳定的循环寿命和良好的倍率性能。在300 mA g的电流密度下循环200次后，可逆容量可达1042 mAh g。200次循环的平均放电容量达到926 mAh g。这证明了这种材料结构的优越性及其作为高性能锂离子电池负极的巨大潜力。这项工作表明了一种利用金属有机骨架合成其介孔骨架衍生物的新策略。
