Targeting the Dissolution of Polyselenides: An Investigation Involving UV–Vis Spectroscopy and Interlayer Development

Li–Se batteries are promising energy storage systems due to the high theoretical volumetric capacity and electrical conductivity of selenium. However, the formation of dissolved polyselenide in ether-based electrolytes is one of the main factors affecting the electrochemical performance of Li–Se batteries. Herein, the presence and solubility of polyselenides in ether-based electrolytes are initially investigated using UV–vis spectroscopy and compared with carbonate-based solvents. Then, to address the polyselenide shuttle effect, SnCl₂-containing poly(acrylonitrile-co-vinylpyrrolidone) (oPANVP/SnCl₂) nanofibrous interlayer is utilized to retain the dissolved compounds. The absorption capacity of this interlayer is investigated and quantitatively demonstrated by UV–vis spectroscopy. The cell with the interlayer achieves a discharge capacity of 266 mAh g⁻¹ after 150 cycles, significantly higher than the cell without the interlayer. Furthermore, 3-electrode electrochemical impedance spectroscopy and open-circuit voltage monitoring are conducted to investigate the impact of the oPANVP/SnCl₂ interlayer on the solubility of polyselenides. The improved electrochemical results indicate that ether-based electrolytes can be successfully utilized in Li–Se batteries when an effective interlayer is present to adsorb polyselenides.