Dual Effects of Metal and Organic Ions Co-Intercalation Boosting the Kinetics and Stability of Hydrated Vanadate Cathodes for Aqueous Zinc-Ion Batteries

摘要

For the development of aqueous zinc-ion batteries, exploitingvanadium-based cathode materials with quick kinetics and acceptable cyclingstability is crucial. Herein, to achieve these goals, transition metal ions (Zn~(2+))and organic ions (C_5H_(14)ON~+ and Ch~+) are introduced into layered hydratedV2O5. The intrinsic high conductivity of Ch~+ and the oxygen vacanciesgenerated through ion pre-intercalation accelerate the electrical mobility byoptimizing the electronic structure. The Zn~(2+) stabilizes the layered structureand the expanded interlayer spacing improves the ionic diffusivity. Thesynergistic effect of pre-intercalated Zn~(2+) and Ch~+ results in the (Zn_(0.1),Ch_(0.1))V_2O_(4.92)·0.56H_2O cathode exhibiting a discharge capacity of473 mAh g~(?1) at 0.1 A g~(?1) with a high energy efficiency of 88% and excellentcycling stability with 91% retention after 2000 cycles at 4 A g~(?1). Ex situcharacterizations and density functional theory calculations reveal a reversibleintercalation mechanism of Zn~(2+), and the improved electrochemical kineticsare attributed to the altered electronic conductivity and the reduced bindingenergy between Zn~(2+) and host O~(2?).