Single and multilayer composite electrolytes for enhanced Li-ion conductivity with restricted polysulfide diffusion for lithium–sulfur battery

Abstract

Lithium–sulfur battery is a promising energy source to achieve high energy density at low cost, but its commercialization has been being impeded by a few huddles associated with Li dendrite growth, polysulfide shuttle, and flammability, due to the utilization of liquid electrolytes. In this study, the single- and multi layered flexible composite electrolytes comprising organic poly(arylene ether sulfone)-g-poly(ethylene glycol) and inorganic Li6PS5Br nanoparticles are designed. Both composite electrolyte membranes exhibit excellent mechanical flexibility and thermal stability up to 200 °C. The single-layer composite electrolyte illustrates high ionic conductivity of 2.4 ⅹ 10−3 S/cm because of the self-assembled poly(ethylene glycol) domains accommodating large amount of free charge carriers. Even though the multilayer electrolyte membrane shows slightly lower conductivity of 8.7 ⅹ 10−4 S/cm, it provides quite high lithium-ion transference number of 0.81 with self-extinguishing ability and effective suppression of Li dendrite growth and polysulfide diffusion because of the highly selective Li6PS5Br layer. Accordingly, the Li/S cell assembled with multilayer composite electrolyte shows outstanding cyclic stability retaining 99.2% after 100 cycles at 0.1 C-rate. Those results demonstrate the application possibility of the prepared solid electrolytes for high safety and high performance lithium–sulfur battery.