2D Dynamic Heterogeneous Interface Coupling Endowing Extra Zn2+ Storage

Aqueous zinc-ion battery (AZIBs) is expected to be an ideal device for large-scale energy storage for its high safety and low cost. However, it is still a challenge to achieve both high energy density and high stability. Herein, in situ liquid-phase growth exfoliation is developed to obtain V5O12 nanosheets, which is then combined with Ti3C2 nanosheets to construct two-dimensional heterostructure (2D HVO@Ti3C2) with interfacial V-O-Ti bonds. 2D HVO@Ti3C2 exhibits a dynamic interface coupling during discharging/charging, accompanied by break/reconstruction of interfacial V-O-Ti bonds. The dynamic interface coupling provides a reversible electron transfer channel and endows the inert Ti3C2 with electrochemical activity in AZIBs, making it an additional electron acceptor and donor, and promoting the insertion of more Zn2+. Therefore, a capacity beyond the theoretical capacity of HVO is obtained for the HVO@Ti3C2. Additionally, the reversible 2D dynamic interface coupling can also effectively alleviate the structural damage during the cycling process. Then, the ultra-high capacity (457.1 mAh g(-1) at 0.2 A g(-1), over 600 mAh g(-1) based on the mass of HVO) and high stability (88.9% capacity retention after 1000 cycles at 5 A g(-1)) are achieved. This interface coupling mechanism provides an exciting strategy for the high energy density and high stability of AZIBs.

Automated summary

In situ liquid-phase growth exfoliation is developed to obtain V5O12 nanosheets, which are then combined with Ti3C2 nanosheets to construct a 2D heterostructure HVO@Ti3C2. The dynamic interface coupling during discharging/charging provides a reversible electron transfer channel and promotes the insertion of more Zn2+, leading to an ultra-high capacity and high stability in AZIBs. This interface coupling mechanism provides an exciting strategy for the high energy density and high stability of AZIBs.