Lithium and Magnesium Polymeric Electrolytes Using Poly(Glycidyl Ether)-Based Polymers With Short Grafted Chains

Recently, poly(allyl glycidyl ether) (PAGE) has attracted great interest as polymer electrolyte for Li-ion transport with conductivities values well above the benchmark polyethylene oxide at temperatures below 60 °C. Here, we prepared lithium and magnesium polyelectrolytes by using two novel PAGE-based matrixes containing thioether and sulfone functionalities located in a short side chain inserted by chemical post-functionalization of PAGE. The synthesized PAGE, poly(2-(ethyl thio) propyl glycidyl ether) (PEthioPGE) and poly(2-(ethyl sulfone) propyl glycidyl ether) (PEsulfoPGE) were all amorphous at any temperature with Tg between -80 °C and -30 °C. These polymers were used to formulate electrolytes with different Li and Mg salts. The impact of the side chain, used salt and temperature on the ion conductivity was studied in detail. Ionic conductivities as high as 5.1 x 10-4 S cm-1 at 90 °C can be reached by PAGE-LiTFSI and PEthioPGE-LiTFSI, values comparable to PEO-LiTFSI with identical salt loading. Using LiCl, PEthioPGE outperforms all the other polymers including PEO with the highest conductivity value at 90 °C (1.1 x 10-5 S cm-1). Moreover, the studied complexes with magnesium salts showed promising ion conductivities, comparable to lithium and up to 4.1 x 10-4 S cm-1 at 90°C for PAGE-Mg(TFSI)2. The results presented here, highlight the possibility to tune the structure and the complexation properties of poly(glycidyl ether)-based electrolytes towards both lithium and magnesium ions.