Monodispersed flower-like MXene@VO2 clusters for aqueous zinc ion batteries with superior rate performancet

摘要

Monoclinic B phase VO2 with a distinctive tunnel structure is regarded as a viable cathode material for use in aqueous zinc ion batteries(AZIBs).However,the low electron conductivity and poor rate performance prevent it from being used further.Herein,we report 3D flower-like MXene nanosheets loaded with the VO2 cluster(MXene@VO2)synthesized via a one-step hydrothermal process,where MXene nanosheets were spontaneously stacked as a skeleton for the growth of VO2 nanobelts.The synergistic effect between MXene nanosheets with high electronic conductivity and VO2 nanobelts with a unique tunnel structure benefitted the electron and Zn2+ transport;the 3D hybrid structure with a high specific surface area provided an increased contact area with the electrolyte and a shortened distance of the Zn2+ transfer path.As a result,this material exhibits a promising Zn2+ storage behavior with a superior rate capability(363.2 mA h g~(-1)at 0.2C and 169.1 mA h g~(-1)at 50C)and outstanding long-cycling performance(206.6 mA h g~(-1)and 76 capacity retention over 5000 cycles at 20C).In addition,a self-charging battery could be prepared by using oxygen in air to oxidize vanadium oxide with lower valence states.Our prepared MXene@VO2 composite with a synergistic effect has been proved to be a promising cathode for AZIBs,offering a progressive paradigm for the development of AZIBs.