Toward High-Performance Zinc-Ion Batteries: A Dual-Function Cathode with Sr 2 + -Reconfigured Interlayer and Poly(3,4-ethylenedioxythiophene) Polymer Coating for Kinetics and Stability

Vanadium-based oxides possess unique superiorities in aqueous zinc-ion batteries (AZIBs) due to their high theoretical specific capacity and open crystal framework properties. However, only limited studies have been conducted on e vanadium dissolution and kinetics optimization, which are essential to achieve high-performance cathodes. If an elastic protective layer with a highly conductive nature and abundant zincophilic sites could be integrated on the interfaces of the vanadium oxide, it is anticipated that both the electric conductivity and structural stability of the vanadium oxide could be enhanced. Hence, in this work, using SrVOH@PEDOT as a model system, we investigated the effects of PEDOT/Sr 2+ incorporation and proposed a universal strategy for vanadium-based materials. The high-quality SrVOH@PEDOT cathode showed more robust interlayer stability coupled with a uniformly thick, highly-conductive layer. Preintercalated Sr ions functioned as pillars to stabilize the layered structure. Concurrently, the conductive polymer poly(3,4-ethylenedioxythiophene) coating on VOH isolated the cathode from water, thus suppressing specific capacity fade caused by cathode dissolution. Therefore, the SrVOH@PEDOT cathode exhibited excellent discharge specific capacity, good rate performance, and satisfactory cycling performance. It exhibited a capacity of 454 mAh g –1 at 0.5 A g –1, as well as 91.45% capacity retention after 200 cycles at 1 A g –1 and 85.2% capacity retention after 5000 cycles at 5 A g –1 . The battery also possessed high energy and power densities of 342 Wh kg –1 at 376.5 W kg –1 and 182.3 Wh kg –1 at 2144.1 W kg –1 . In addition, a reversible intercalation mechanism for Zn 2+ was revealed by ex-situ characterization. This work presents a simple and synergistic design strategy to achieve high-quality cathodes for aqueous zinc-ion batteries.