Preparation and properties of lithium sulfonated polyoxadiazoles electrolyte

A series of sulfonated polyoxadiazoles (SPOD) with different monomer ratios were synthesized by using hydrazine sulfate (HS), terephthalic acid (TPA) and 4,4'-diphenyl ether dicarboxylic acid (DPE) as monomers, fuming sulfuric acid as solvent and dehydrating agent. Then, the SPOD films were obtained by the solution casting method. Finally, the SPOD films were neutralized with lithium hydroxide to form Li-SPOD polymer electrolytes films. The effects of two monomer ratios of TPA and DPE on the structure and properties of Li-SPOD were studied. Results show that SPOD can be obtained with different monomer ratios, and the sulfonic acid group was grafted on the benzene ring of DPE chain segments. The aggregation structure difference among Li-SPOD electrolyte films is small. Their thermal stabilities are excellent, and the initial thermal decomposition temperature are all above 450℃. The mechanical properties of Li-SPOD films decrease slightly with the increase of DPE contents. The conductivities of Li-SPOD electrolyte films are about 10^-5S·cm^-1, and gradually decrease with the increase of DPE content. Their electrochemical stability are good, and the decomposition voltages are all above 4.0 V.