Ionic conductivity promotion of polymer membranes with oxygen-ion conducting nanowires for rechargeable lithium batteries

Solid polymer electrolytes have great potentials to overcome safety issues of organic liquid electrolytes for lithium-ion batteries (LIBs). However, the poor lithium-ion migration within solid polymers impedes the broad applications. In this work, composite polymer electrolytes (CPEs) are prepared by dispersing oxygen-ion conducting Sm-doped CeO 2 (SDC) nanowires into the polyvinylidene fluoride matrix. The ionic conductivity and the lithium-ion transfer number are greatly enhanced after the introduction of the SDC nanowires to CPEs, thanks to the increase of amorphous regions resulted from the SDC filler, the Lewis acid-base interaction due to the positively charged oxygen vacancies , and the partial dehydrofluorination. Specifically, CPE-10 with 10 wt% of the SDC nanowires reaches the ionic conductivity of 9.09 × 10 −5  S cm −1 at 30 °C with a lithium-ion transfer number of ∼0.40. Also, CPE-10 exhibits a relatively high oxidation potential of 4.89 V versus Li + /Li. Impressively, a quasi-solid-state CR2032 LiFePO 4 /CPE-10-20 μL/Li battery exhibits the initial capacity of as high as 155.1 mAh g −1 at 1 C, and it still delivers 155.3 mAh g −1 after 130 cycles, as well as the favorable rate performance (e.g., 135.1 mAh g −1 at 4 C). Besides, a lithium-oxygen battery (Super P/CPE-10-5 wt% LiI/Li) exhibits the initial discharge capacity of 5325 m A h g c a r b o n - 1 with the coulombic efficiency of 85.7%. Our work demonstrates that CPEs with the oxygen-ion conducting SDC nanowires could be potentially applied in quasi-solid-state LIBs and lithium-oxygen batteries.