Synthesis of polymer electrolytes improved by the addition of KNbO₃ for rechargeable batteries

Lithium-ion rechargeable batteries (LIBs), essential components of electronic devices and energy storage systems, have attracted considerable attention due to their role in improving efficiency and safety.A key component of LIBs is the electrolyte, responsible for transporting lithium ions between the positive and negative electrodes.This study aims to develop a solid polymer electrolyte (SPE) composed of lithium perchlorate (LiClO), polyvinyl alcohol (PVA), and polyethylene oxide (PEO), enhanced by the addition of potassium niobate (KNbO) to improve LIB performance.The main objective of the research is the development of polymeric solid electrolytes based on pure LiClO/PVA-PEO and improved by the insertion of KNbO, to replace conventional liquid electrolytes for use in rechargeable lithium-ion batteries.Originally, KNbO powders were synthesized in the laboratory from specific precursors (hydrated potassium oxalate, KCO2HO, and niobium pentoxide, NbO), calcined at 600C.Subsequently, pure SPE (A = LiClO/PVA-PEO) and the SPE with the addition of KNbO (B) were synthesized.Using a digital caliper, the thickness was measured and the area of the SPE was calculated.After a one-week curing time, the dried SPE was placed between two stainless steel plates (sandwich) of the same dimensions for electrochemical analyses.Electrochemical impedance spectroscopy (EIS) and chronoamperometry tests were performed using the AUTOLAB PGSTAT 128 N potentiostat, coupled with the NOVA 2.0.1 software copyright 2016, Metrohm Autolab B.V. X-ray diffraction (XRD) with Rietveld refinement identified two crystalline phases of KNbO: cubic (JCPDS No. 01-083-3855) and tetragonal , with a residual profile factor (S) of 1.21 and a correlation coefficient () of 1.45, indicating good fit.Scanning Electron Microscopy (SEM) revealed a morphology of dense KNbO clusters with irregular sizes, uniformly distributed in the polymer matrix.Electrochemical impedance spectroscopy (EIS) showed a 38.78% increase in ionic conductivity after adding KNbO (SPE/B) compared to pure SPE (A).Combined EIS and chronoamperometry provided current densities and charge transport