Sulfonated poly(vinyl alcohol) as an artificial solid electrolyte interfacial layer for Li metal anode

Abstract

The cycle performance of Li metal batteries with high energy-density is hindered by the stability of Li metal anode. In this manuscript, sulfonated poly(vinyl alcohol) (SPVA) was synthesized and used as an artificial solid electrolyte interfacial (SEI) layer to construct stable Li metal anode interface. The ionic conductivity of SPVA coating layer in liquid electrolyte was calculated according to the theories of interfacial polarization in heterogeneous systems by dielectric method. In the Li|PE|SPVA/Cu or Li/SPVA|PE|SPVA/Li cells, Li deposits beneath the SPVA layer, surviving from the corrosion of liquid electrolyte and excessive volume expansion. Benefited from the constructed stable artificial SEI layer, the interfacial polarization and internal resistance in the symmetric cells are reduced. The cycle performance of LiFePO4|PE|SPVA/Li cell has been greatly improved, which could be stably cycled for more than 500 cycles.