W-based MOF derived ZnWO4/ZnO@C hierarchical nanoflakes with superior lithium storage performance

Tungstate-based materials as lithium-ion battery anodes have drawn multitudinous attention owing to their great theoretical capacity and typical multielectron transfer process. Nevertheless, their slow electrochemical reaction kinetics and big volume variation often trigger poor lithium storage properties. Herein, novel ZnWO4/ZnO@C hierarchical nanoflakes are engineered via a facile W-based metal-organic framework (W-MOF) template method. The ZnWO4/ZnO@C nanoflakes with a rectangular shape and high porosity are constructed by carbon-coated nanocrystal subunits. The unique composition and microstructure of ZnWO4/ZnO@C can shorten the pathway for Li+/electron transport, expand the contact with the electrolyte, improve the electrical conductivity, and fortify structural stability. Consequently, the ZnWO4/ZnO@C material as LIBs anodes delivers a high reversible capacity of 734 mAh g-1 after 150 cycles at 200 mA g-1, decent rate capability (426 mAh g-1 at 1000 mA g-1), and outstanding cyclic stability (93.8 % capacity retention over 350 cycles at 500 mA g-1). The in-situ XRD combined with ex-situ XPS and FT-IR was performed to elucidate the lithium storage mechanism of ZnWO4/ZnO@C. This work presents a simple and efficient approach for the synthesis of novel tungstate-based anodes for lithium-ion battery applications.