Characterisation of tetraPEG gel electrolytes for lithium-ion batteries

The present master thesis is disclosing an original strategy for the synthesis of a gel polymer electrolyte (GPE) targeting lithium ion battery applications. This GPE consists in a covalent amphiphilic polymer conetwork prepared by the interconnection of four-armed star poly(vinylidene fluoride) (PVDF) end-functionalized with benzaldehyde groups and four-armed star poly(ethylene glycol) (PEG) end-functionalized with benzaacylhydrazide groups. The gelation process catalyzed by acetic acid is taking place in dimethylformamide (DMF). The gelation medium is also containing a room temperature ionic liquid, namely lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) : 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (LiTFSI : EMIM-TFSI 1:9 molar ratio). After gelation and evaporation of the DMF cosolvent, the resulting GPE was characterized by thermal, mechanical and electrochemical techniques. The GPE exhibited a good thermal stability, a satisfying mechanical integrity (Young modulus of 10 MPa), a 4 V electrochemical stability, and a good room temperature ion conductivity of 0.6 mS cm–1.