Superior potassium and zinc storage in K-doped VO2(B) spheres
The abundant natural resources and low cost benefits of zinc-ion batteries (ZIBs) and potassium-ion batteries (KIBs) offer a better alternative to lithium-ion batteries (LIBs). Nevertheless, large radius of K+ and high charge density of Zn2+ lead to sluggish electrochemical kinetics and the development of appropriate electrode materials for KIBs and ZIBs is therefore very important. Herein, hierarchical K-doped brookite vanadium dioxide (K-VO2(B)) spheres prepared via a simple microwave-assisted hydrothermal approach are proposed. K-VO2(B) as an anode material for PIBs shows the enhanced electrochemical performance in terms of high capacity (~420 mA h g-1), exceptional rate capability and long-term cycling performance (500 cycles). For ZIBs, it also achieves a high capacity of 350 mA h g-1 at 500 mA g-1 and 122 mA h g-1 at an extremely high rate of 50 A g-1. The outstanding PIBs and ZIBs performance of the K-VO2(B) is mainly benefit from the improved ion diffusion coefficients after K-doping and the occurrence of inherently stable (de)intercalation reactions.