Sandwich Structure of 3D Porous Carbon and Water‐Pillared V 2 O 5 Nanosheets for Superior Zinc‐Ion Storage Properties

Abstract Vanadium oxides are promising cathode materials for rechargeable aqueous zinc‐ion batteries (RAZIBs). However, the self‐agglomeration and poor ion/electron conductivity of vanadium oxides in the charge/discharge process usually lead to low capacity and capacity attenuation, which limits their commercial application. Herein, we report a facile and mass‐production method for fabricating 3D porous carbon/water‐pillared V 2 O 5 nanosheet composites with sandwich structure (PC/V 2 O 5 ⋅ n H 2 O), which can further reduce the preparation cost of vanadium‐oxide‐based cathodes. Moreover, the excellent structural characteristics of PC/V 2 O 5 ⋅ n H 2 O not only effectively inhibits the aggregation and stacking of V 2 O 5 ⋅ n H 2 O but also increases the contact area between the active substance and the electrolyte, which is conducive to the transport of zinc ions and improves the electrochemical performance of RAZIBs. The PC/V 2 O 5 ⋅ n H 2 O cathode displays an excellent rate performance (325.3 mAh g −1 at high current density 20 A g −1 ), a high specific discharge capacity of 415.4 mAh g −1 at 0.5 A g −1 , an outstanding cyclic stability, and capacity retention (after 1000 cycles the capacity retention rate about 97.1 %). Ex situ XRD patterns reveal that the charge/discharge process of the PC/V 2 O 5 ⋅ n H 2 O electrode undergoes a reversible intercalation and conversion process. The method used in this work provides an idea for large‐scale synthesis of vanadium‐based cathode materials for multivalent batteries.