 Recham "et al" first demonstrated that fluorosulfates have a reversible intercalation mechanism with K, Na and Li, since then, other polyanionic compound such as K3V2(PO4)3, KVPO4F have been studied, while still limited to the complex synthesis process.Worth noting is an orthodox approach of using organic compound as cathode for potassium-ion battery, such as PTCDA, a red pigment which can bond with 11 potassium ion within single molecule.Electrolytes