Improved Li-S Battery Performance with Dispersant/Plasticizer Co-Assisted Modification of a Poly(ethylene Oxide)/Li6.4La3Zr1.4Ta0.6O12 Solid Electrolyte.

Abstract

Lithium-sulfur batteries (LSBs) have garnered considerable attention over the past decade due to their high specific capacity and energy density. However, the poor safety and polysulfide shuttle phenomenon associated with liquid LSBs have been widely criticized. Solid-state electrolytes have the potential to overcome these issues, but their lower ionic conductivity and nonideal electrode/electrolyte interface contact as compared with liquid electrolytes remain a challenge in all-solid-state LSBs (ASSLSBs). This study applies the untested method of introducing a combination of dispersant and plasticizer as a "co-assisted" additive. We develop a polymer/ceramic composite electrolyte by combining poly(ethylene oxide)s, Li6.4La3Zr1.4Ta0.6O12 ceramic powder, the dispersant pluronic (C3H6O·C2H4O)x (F127), and the plasticizer succinonitrile (C2H4(CN)2) (SN). The dispersant F127 effectively prevents the aggregation of ceramic powders, whereas the plasticizer SN reduces the crystallinity of the composite polymer electrolytes and decreases the interface impedance, thereby enhancing the overall ion conductivity. The resulting composite electrolyte exhibits an ionic conductivity of 1.24 × 10-4 S cm-1 at room temperature, and when coupled with a commercial sulfur electrode, a high capacity of 1085 mA h g-1 is achieved. In addition, the batteries demonstrate a high capacity retention of 71% after 100 cycles at a current density of 0.2 C at room temperature, demonstrating considerable promise for ASSLSB applications.