Ultraviolet-cured composite polymer electrolyte containing deep-eutectic-solvent and aluminum oxide filler for lithium-metal batteries with enhanced cycle life

[Display omitted] •The electrochemical stability is well improved upon the immobilization of DES in polymer matrix and introduction of Al2O3 filler.•The battery performance is greatly improved by the synergistic effect exerted by the combination of immobilizing DES and incorporating Al2O3 filler.•Al2O3 filler is introduced into the system to further enhance the electrochemical properties of the electrolytes.•The electrolyte with 5 wt% Al2O3 possess the highest ionic conductivity and the best cyclic performance. Deep-eutectic-solvent (DES), which is formed by mixing LiTFSI and N-methylacetamide in a molar ratio of 1:4, can be seen as a promising additive in electrolyte composition. In this study, DES is immobilized in the ultraviolet-cured poly(butyl acrylate-co-acrylonitrile) (PBA-co-PAN) cross-linked by 1,6-hexanediol diacrylate (HDDA) to serve as novel polymer electrolytes (PEs) for lithium batteries. Moreover, aluminum oxide (Al2O3) filler is introduced into the system to further enhance the electrochemical properties of the electrolytes. The results indicate that the conductivity value reaches 6.8 × 10-4 S cm−1 and an improved electrochemical stability up to 4.6 V can be achieved by the sample with 5 wt% Al2O3 addition (CPE5), which are much better than those of the system with DES as the electrolyte. By virtue of above superiority, the assembled Li//CPE5//LFP cell can deliver a discharge capacity of 155 mAh/g with a 95.3 % retention after 400 cycles at 0.2C rate at room temperature. Our study demonstrated that the battery performance is greatly improved by the synergistic effect exerted by the combination of immobilizing DES and incorporating Al2O3 filler in PBA-co-PAN polymer matrix.