One-dimensional sepiolite confined ionic liquids structure to improve the electrochemical performance of polyethylene-oxide based composite polymer electrolyte

Polyethylene-oxide (PEO) based composite polymer electrolytes (CPEs) with one-dimensional sepiolite confined ionic liquids (ILs) structure is constructed to further improve Li+ conductivity and reduce cost. Silicon nanorods (SNRs) is obtained by microwave-assisted acid activation of sepiolite and then ILs is confined into SNRs by supercritical CO2 fluid. The specific surface area of SNRs reduces from 170.88 m2 g-1 to 2.19 m2 g-1 after ILs confining, and the morphology and component of ILs in SNRs channel are clearly detected, indicating that the SNRs confined ILs structure (ILs@SNRs) is successfully obtained. The Li+ conductivity of CPEs increases from 1.40 × 10-6 S cm-1 to 0.922 × 10-4 S cm-1, which indicates that ILs confined in SNRs provide a fast channel for Li+ transmission. Besides, the reduction of PEO crystallinity is also favorable to Li+ transmission. The corresponding lithium symmetrical battery and LiFePO4 battery has excellent electrochemical performances. The good rate performance is attributed to the high Li+ migration number of 0.261 compare to 0.122 of PEO. Compared with the simple mixing of polymer and ILs, the confined ILs in SNRs channel will not be lost, which maintains the stability of Li+ transmission and reduces the consumption amount of ILs thus greatly reducing the cost of CPEs.