K2[(VOHPO4)2(C2O4)]·2H2O as a high-potential cathode material for potassium-ion batteries

Abstract

Potassium-ion batteries (KIBs) represent a promising energy storage solution owing to the abundance of potassium resources. The efficacy of KIBs relies significantly on the electrochemical attributes of both their electrode materials and electrolytes. In the current investigation, we synthesized a layered compound K₂[(VOHPO₄)₂(C₂O₄)]·2H₂O via a heterogeneous nucleation approach and assessed its viability as a cathode material for KIBs. When integrated with a salt-concentrated electrolyte with oxidation stability over 6 V, the compounds exhibit a high discharge potential of 4.1 V (vs. K⁺/K) alongside a reversible capacity of 106.2 mAh g⁻¹. Furthermore, there is no capacity decay after 500 cycles at 100 mA g⁻¹. This study shows the promise of layered metal organic frameworks as high-potential materials for KIBs.