Interfacial adsorption-insertion mechanism induced by phase boundary toward better aqueous Zn-ion battery

Biphasic and multiphasic compounds have been well clarified to achieve extraordinary electrochemical properties as advanced energy storage materials.Yet the role of phase boundaries in improving the performance is remained to be illustrated.Herein,we reported the biphasic vanadate,that is,Na_(1.2)V_(3)O_(8)/K_(2)V_(6)O_(16)·1.5H_(2)O(designated as Na0.5K0.5VO),and detected the novel interfacial adsorption-insertion mechanism induced by phase boundaries.Firstprinciples calculations indicated that large amount of Zn^(2+)and H^(+)ions would be absorbed by the phase boundaries and most of them would insert into the host structure,which not only promote the specific capacity,but also effectively reduce diffusion energy barrier toward faster reaction kinetics.Driven by this advanced interfacial adsorption-insertion mechanism,the aqueous Zn/Na_(0.5)K_(0.5)VO is able to perform excellent rate capability as well as long-term cycling performance.A stable capacity of 267 mA h g^(-1)after 800 cycles at 5 A g^(-1)can be achieved.The discovery of this mechanism is beneficial to understand the performance enhancement mechanism of biphasic and multiphasic compounds as well as pave pathway for the strategic design of highperformance energy storage materials.