Interfacial chemistry and ion-transfer mechanism for a tailored poly(thioether)-enabled hybrid solid polymer electrolyte with electrochemical properties in all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries are regarded as promising high safety- and high energy-density-energy-storage devices. However, the dissolution of lithium polysulfide intermediate species and the growth of dendrites on the lithium metal anode during cycling causes capacity fading and hidden security problems. Herein, we designed a composite solid polymer electrolyte based on poly(thioether)/polyethylene oxide (PTE/PEO) with a sizeable electrochemical window, enhanced ionic conductivity, and attractive mechanical properties. In the PTE composite electrolyte, the interactions of PTE with the -CF3 and SO2- groups of the (NSO2CF3)2- anion enhanced the dissociation of lithium salts to release more Li+ and improve the ionic conductivity. Also, traces of short-chain polysulfides could be observed on the cathode, demonstrating the successful conversion of the longer-chain polysulfides, leading to minimum parasitic reactions, preventing polysulfide dissolution, and inhibiting lithium dendrite. Benefiting from the improvements in electrolytes, high capacity and safety of lithium-sulfur batteries could be achieved. The solid polymer electrolyte we are introducing benefited from the synergy between polyethylene oxide and oligomer poly(thioether) plasticizer, which exhibits enhanced electrochemical, mechanical tensile and good thermochemical properties.