Semester of Graduation

Fall 2019

Degree

Master of Science (MS)

Department

Mechanical & Industrial Engineering

Document Type

Thesis

Abstract

Rechargeable aqueous zinc-ion batteries (ZIBs) have been intensively studied as novel promising large-scale energy storage systems recently, owing to their advantages of high abundance, cost effectiveness, and high safety. However, the development of suitable cathode materials with superior performance are severely hampered by the sluggish kinetics of Zn2+ with divalent charge in the host structure.

Our Work demonstrates boosting the electrochemical performances of nanostructured cathode materials for aqueous ZIBs. The first project is focused on the interlayer-expanded V6O13∙nH2O nanosheets as promising cathodes. Benefiting from the synthetic merits of its favorable architecture and expanded interlamellar spacing resulted from its structural water, the V6O13∙nH2O cathode exhibits outstanding electrochemical performances with a high reversible capacity of 395 mAh g-1 at 0.1 A g-1, superior rate capability, and durable cycling stability with a capacity retention of 87% up to 1000 cycles. In addition, the reaction mechanism is significantly investigated in detail. Moreover, the second project is focused on the synthesis of NH4V3O8∙1.9H2O nanobelts and investigation of the electrochemical properties in aqueous and quasi-solid-state (QSS) ZIBs. When examined in aqueous ZIBs, this cathode material enables ultrafast Zn2+ diffusion and highly reversible process, exhibiting superior electrochemical performances with a high discharge capacity of 463 mAh g-1 at 0.1 A g-1, excellent rate capability (183 mAh g-1 even at 10 A g-1), and impressive cycling stability with a capacity retention of 81% after 2000 cycles maintaining a decent discharge capacity of 166 mAh g-1 at 10 A g-1. Furthermore, the NH4V3O8∙1.9H2O electrode can deliver a high energy density of 332 Wh kg-1 at a power density of 72 W kg-1 and maintain an energy density of 101 Wh kg-1 at a high power density of 5519 W kg-1. The NH4V4O10∙1.6H2O is also studied as cathode materials for aqueous ZIBs, showing inferior electrochemical properties when compared with NH4V3O8∙1.9H2O. In addition, the QSS flexible Zn/NH4V3O8∙1.9H2O battery is also studied, showing durable cycling performance and stable electrochemical properties under various bending states.

The present studies demonstrate that the V6O13∙nH2O nanosheets and NH4V3O8∙1.9H2O nanobelts are emerging as high-potential cathode materials for rechargeable zinc-ion battery, and it sheds light on the rational design of novel cathodes for grid-scale energy storage devices.

Committee Chair

Wang, Ying

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