Methylene blue intercalated vanadium oxide with synergistic energy storage mechanism for highly efficient aqueous zinc ion batteries

With the rise of aqueous multivalent rechargeable batteries, inorganic-organic hybrid cathodes have attracted more and more attention due to the complement of each other's advantages. Herein, a strategy of designing hybrid cathode is adopted for high efficient aqueous zinc-ion batteries (AZIBs). Methylene blue (MB) intercalated vanadium oxide (HVO-MB) was synthesized through sol-gel and ion exchange method. Compared with other organic-inorganic intercalation cathode, not only can the MB intercalation enlarge the HVO interlayer spacing to improve ion mobility, but also provide coordination reactions with the Zn2+ to enhance the intrinsic electrochemical reaction kinetics of the hybrid electrode. As a key com-ponent for the cathode of AZIBs, HVO-MB contributes a specific capacity of 418 mA h g-1 at 0.1 A g-1, high rate capability (243 mA h g-1 at 5 A g-1) and extraordinary stability (88% of capacity retention after 2 000 cycles at a high current density of 5 A g-1) in 3 M Zn(CF3SO3)2 aqueous electrolyte. The electrochemical kinetics reveals HVO-MB characterized with large pseudocapacitance charge storage behavior due to the fast ion migration provided by the coordination reaction and expanded interlayer distance. Furthermore, a mixed energy storage mechanism involving Zn2+ insertion and coordination reaction is confirmed by various ex-situ characterization. Thus, this work opens up a new path for constructing the high perfor-mance cathode of AZIBs through organic-inorganic hybridization.(c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study adopts a strategy of designing hybrid cathodes for efficient aqueous zinc-ion batteries. Methylene blue (MB) intercalated vanadium oxide (HVO-MB) is synthesized through sol-gel and ion exchange methods, and it exhibits high specific capacity, high rate capability, and extraordinary stability in 3 M Zn(CF3SO3)2 aqueous electrolyte. The electrochemical kinetics reveal that HVO-MB has large pseudocapacitance charge storage behavior due to fast ion migration provided by coordination reactions and expanded interlayer distance.