Highly monodispersed Fe2WO6 micro-octahedrons with hierarchical porous structure and oxygen vacancies for lithium storage

High-volume capacity electrode materials are the key to the development and application of lithium-ion batteries in electric vehicles and small consumer electronics. Here, through simply calcination the W-based metal-organic frameworks, a novel Fe2WO6 hierarchical porous octahedra with oxygen vacancies are successfully constructed. Oxygen vacancies can enhance the conductivity of the material, provide more Li+ storage sites, while the hierarchical porous structure effectively buffers the volume expansion and promotes the diffusion of the electrolyte. Besides, by introducing the heavy element W, the compact density of Fe2WO6 is as high as 2.9 g cm-3. Thus, an ultrahigh volumetric capacity of 4785 mAh cm? 3 (0.2 A g+1), and superior rate capability of 2323 mAh cm-3 (4.0 A g+1) could be achieved by Fe2WO6 anode, which is the best performance of W-based anode so far. Furthermore, the mechanism of the significant increment in capacity is also investigated. The new findings indicate that the phase transition and structural rearrangement of the Fe2WO6 electrode, along with the enhanced reversible formation and decomposition of the polymer/gel-like film, collectively result in the capacity evolution during cycling. Remarkably, the introduction of oxygen vacancies and high density makes hierarchical porous Fe2WO6 a promising anode for high volumetric lithium storage.

Automated summary

By introducing oxygen vacancies and bulky W element, a high-capacity and high-performance electrode material Fe2WO6 has been achieved, providing new possibilities for high volumetric lithium storage.