Li+ transport properties of sulfolane-based gel polymer electrolyte and effective suppression of lithium polysulfide dissolution in lithium-sulfur batteries

Sulfolane (SL)-based gel polymer electrolytes composed of a polyether-based host polymer were investigated for long-lifecycle lithium-sulfur batteries. The proposed electrolytes were expected to cause chemical and physical suppression of Li2Sn dissolution and diffusion owing to the low Li2Sn solubility, derived from the highly concentrated SL-based electrolytes, and low Li2Sn diffusion, derived from the host polymer, respectively. The Li+ transport properties, and Li+-SL and Li+-anion interactions, were analyzed by alternating current impedance measurements and Raman spectroscopy, respectively. The relationships between gel polymer electrolyte composition and Li+ coordination structure/Li+ transport properties were also investigated. The Li-S cells containing gel polymer electrolytes exhibited a sufficient discharge capacity in the first cycle (approx. 1150 mA h g(-1)) and stable charge discharge operation for 100 cycles. Application of the proposed electrolytes resulted in high battery performance owing to chemical and physical control of Li2Sn dissolution and diffusion, and favorable electrolyte/Li metal interface formation.