Mn2+ pre-intercalated hydrated vanadium oxide as an improved cathode material for aqueous Zn-ion batteries

Hydrated vanadium oxide is a promising cathode material for aqueous Zn-ion batteries due to its tunable open frameworks and intrinsic multivalent states of vanadium. However, its cycling performance is hindered by structural instability and sluggish diffusion kinetics. In this study, we prepared a series of Mn²⁺ pre-intercalated hydrated vanadium oxide (MnVOH) using a hydrothermal method. By adjusting the synthesis temperature, the pre-intercalated Mn²⁺ expanded the interlayer spacing, improving the diffusion kinetics of Zn²⁺ and reducing structural degradation during the intercalation/(de)intercalation process. Consequently, MnVOH-140 exhibited a high specific capacity of 440 mAh/g at the discharge rate of 50 mA/g, superior to VOH-140 (247.5 mAh/g at 50 mA/g), and good cycling stability with 82.1% (113.1 mAh/g) capacity retention after 900 cycles at a high rate of 5A/g, compared to VOH-140 (74.5 mAh/g). The synthesis temperature directly affects the specific capacity and cycling stability of MnVOH.