Abstract
Solid-state sodium ion batteries are frequently referred to as the most promising technology for future energy storage applications. However, developing a solid electrolyte with high ionic conductivity and a wide electrochemical stability window, remains a major challenge. Although solid-polymer electrolytes have attracted great interest due to their low cost, low density and very good processability, they generally have significantly lower ionic conductivity and poor mechanical strength. Here, we report on the development of a low-cost solid polymer electrolyte comprised of poly(ethylene oxide), poly(vinylpyrrolidone) and sodium hexafluorophosphate, mixed with indium arsenide nanowires. We show that the addition of 1.0 percent by weight of nanowires increases the sodium ion conductivity in the polymer to 1.50 × 10-4 Scm−1 at 40° C. This is the highest reported conductivity for any solid polymer electrolyte to date. In order to explain this remarkable characteristic, we propose a new transport model where sodium ions hop between close-spaced defect sites present on the surface of the nanowires, forming an effective complex conductive percolation network. Our work represents a significant advance in the development of novel solid polymer electrolytes with embedded ultrafast 1D percolation networks for next generations of low-cost, high-performance batteries with excellent energy storage capabilities.
High sodium ionic conductivity in PEO/PVP solid polymer electrolytes with InAs nanowire fillers
