Hyper oxidized V6O13+·nH2O layered cathode for aqueous rechargeable Zn battery: Effect on dual carriers transportation and parasitic reactions

Abstract The origin of parasitic reaction formed/dissolved during the electrochemical reaction at the interface and the conformity role of H+/H2O carrier during electrochemical reaction in aqueous Zn salt electrolyte medium of aqueous rechargeable zinc-ion batteries (ARZIBs), is almost recognized halfway; albeit the consequence of this side reaction is not established yet. Through operando X-ray diffraction analyses in two different electrolytes, the parasitic phases and the dual carriers are recognized in a hyper non-stoichiometry layered oxide of V6O13+x.nH2O as cathode. Indeed, galvanostatic intermittent titration (GITT) and operando potentiostatic electrochemical impedance spectroscopy (PEIS) techniques are utilized to clearly show the parasitic phase of thick ZBS (zinc basic sulfate) layer negatively influence the reaction kinetics at the interface in ZnSO4 electrolyte and hence the performance, especially at low current surges. Thus, the layered cathode demonstrated exceptional stability especially in Zn (CF3SO3)2 electrolyte. For example, in a 1 M ZnSO4/1 M Zn (CF3SO3)2 aqueous electrolyte, nearly 80/65% capacity retention over 2,000/5000 cycles at 15 C is exhibited. Comparative GITT investigations on the overpotential and electrochemical kinetics in ZnSO4 and water electrolytes offer strong evidence for the continuous and reversible co-intercalation of dual carriers of Zn2+and H+/H2O.