Pillaring Effect of K Ion Anchoring for Stable V2O5-Based Zinc-Ion Battery Cathodes

Graphical A controllable amount of K + has been intercalated into V 2 O 5 layers to form stable K−O bonds between the V 2 O 5 layers, which works as the “pillar” to greatly enhance its structural stability. The“pillar effect”of the K−O bond can effectively inhibit the dissolution of vanadium-based oxides in the aqueous electrolyte, being crucial to the electrochemical performance of aqueous ZIBs. Aqueous zinc-ion batteries (ZIBs) have attracted widespread attention due to their advantages in safety and environmental benignity. However, achieving a cathode material with stable electrochemical performance for such a system remains an ongoing challenge. Herein, a K 0.5 V 2 O 5 cathode has been designed and synthesized by intercalating of K + into V 2 O 5 , thus constructing a stable crystal structure by forming chemical bonds between V 2 O 5 layers. The successful intercalation of K + has been confirmed by a series of experimental tests and Vienna Ab-initio Simulation Package simulation. These layer-interlinking chemical bonds act as “pillars” to strongly hold the V 2 O 5 layers together and protect them from dissolution. Furthermore, the K 0.5 V 2 O 5 electrode also exhibits excellent durability (about 150 mA h g −1 at 5 A g −1 after 3000 cycles). More impressively, even after standing for three days in the solution of 3 M ZnSO 4 electrolyte, the K 0.5 V 2 O 5 electrode still maintains a high capacity of 92.2 mA h g −1 after 150 cycles, demonstrating its outstanding stability and tolerance in such aqueous electrolyte.