Sandwich-like MXene bridged heterostructure electrode enables anti-aggregation and superior storage for aqueous zinc-ion batteries

Severe aggregation and sluggish reaction kinetics are the main research challenges that impair the storage performance of cathode materials for aqueous zinc-ion batteries. In this work, we report the concept of sandwich-like Ti3C2Tx MXene-bridged VO2 heterostructure (VO2/Ti3C2Tx) design to simultaneously relieve the self-aggregation and boost the interfacial storage kinetics. When acting as cathode material, such VO2/Ti3C2Tx electrode can deliver a high specific capacity 415 mAh g(-1) at 0.1 A g(-1) after 110 cycles, as well as 338 mAh g(-1) at 1 A g(-1) after 300 cycles, much higher than that of the pure VO2 case. Moreover, such electrode also exhibits remarkably rate capability and cyclic stability, which can retain a specific capacity of 170 mAh g(-1) at the high current density of 5 A g(-1) after 1500 cycles. The superior storage performance should be mainly benefited from the mixed-dimensional heterogeneous engineering. In addition, the evolution of crystal structure and valence state of electrode upon cycling were investigated, thus a storage mechanism can be revealed. That is, single VO2 phase would be transformed into the VO2 and ZnxV2O5 center dot nH(2)O mixed phase, with a highly reversible H+/Zn2+ insertion/extraction behavior. Such strategy proposed in this work can be also applied for other kinds of cathode materials and promoting the development of aqueous zinc-ion batteries.

Automated summary

In this study, a sandwich-like Ti3C2Tx MXene-bridged VO2 heterostructure was proposed to address the challenges of aggregation and sluggish reaction kinetics in cathode materials for aqueous zinc-ion batteries. The resulting electrode exhibited improved storage performance with high specific capacity, excellent rate capability, and cyclic stability. The storage mechanism and potential applicability of this strategy for other cathode materials were also investigated.