Magneto-electrochemistry driven ultralong-life Zn-VS2 aqueous zinc-ion batteries

Abstract

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 VS₂ cathode material is manufactured by in situ electrochemical defect engineering under high charge cut-off voltage. Owing to the rich abundant vacancies and lattice distortion in the ab plane, the tailored VS₂ can unlock the transport path of Zn²⁺ along the c-axis, enabling 3D Zn²⁺ transport along both the ab plane and c-axis, and reduce the electrostatic interaction between VS₂ and zinc ions, thus achieving excellent rate capability (332 mA h g⁻¹ and 227.8 mA h g⁻¹ at 1 A g⁻¹ and 20 A g⁻¹, respectively). The thermally favorable intercalation and 3D rapid transport of Zn²⁺ in the defect-rich VS₂ are verified by multiple ex situ characterizations and density functional theory (DFT) calculations. However, the long cycling stability of the Zn-VS₂ 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 Zn²⁺, 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-VS₂ 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⁻¹ after 7400 cycles at 5 A g⁻¹, and delivers the highest energy density of 304.7 W h kg⁻¹ and maximum power density of 17.8 kW kg⁻¹.