Magneto-electrochemistry driven ultralong-life Zn-VS aqueous zinc-ion batteries.

The development of high energy density and long cycle lifespan aqueous zinc ion batteries is hindered by the limited cathode materials and serious zinc dendrite growth. In this work, a defect-rich VS cathode material is manufactured by electrochemical defect engineering under high charge cut-off voltage. Owing to the rich abundant vacancies and lattice distortion in the plane, the tailored VS can unlock the transport path of Zn along the -axis, enabling 3D Zn transport along both the plane and -axis, and reduce the electrostatic interaction between VS and zinc ions, thus achieving excellent rate capability (332 mA h g and 227.8 mA h g at 1 A g and 20 A g, respectively). The thermally favorable intercalation and 3D rapid transport of Zn in the defect-rich VS are verified by multiple characterizations and density functional theory (DFT) calculations. However, the long cycling stability of the Zn-VS battery is still unsatisfactory due to the Zn dendrite issue. It can be found that the introduction of an external magnetic field enables changing the movement of Zn, suppressing the growth of zinc dendrites, and resulting in enhanced cycling stability from about 90 to 600 h in the Zn||Zn symmetric cell. As a result, a high-performance Zn-VS full cell is realized by operating under a weak magnetic field, which shows an ultralong cycle lifespan with a capacity of 126 mA h g after 7400 cycles at 5 A g, and delivers the highest energy density of 304.7 W h kg and maximum power density of 17.8 kW kg.