Helical Covalent Polymers with Unidirectional Ion Channels as Single Lithium-Ion Conducting Electrolytes

作者：Yiming Hu, Nathan Dunlap, Hai Long, Hongxuan Chen, Lacey J. Wayment, Michael Ortiz, Yinghua Jin, A. Nijamudheen, José L. Mendoza-Cortés, Se-Hee Lee, Wei Zhang · 发表于：CCS Chemistry · 年份：2021 · DOI：10.31635/ccschem.021.202101257 · 被引用次数：51 · 研究领域：Advanced Battery Materials and Technologies、Covalent Organic Framework Applications、Advanced battery technologies research

Single-ion conducting polymer electrolytes have attracted great attention as safe alternatives to liquid electrolytes in high energy density lithium-ion batteries. Herein, we report the first example of a crystalline anionic helical polymer as a single lithium-ion conducting solid polymer electrolyte (SPE). Single-crystal X-ray analysis shows that the polymer folds into densely packed double helices, with bundles of unidirectional negatively charged channels formed that can facilitate lithium-ion transportation. Such a helical covalent polymer ( HCP) exhibits excellent room temperature lithium-ion conductivity (1.2 x 10-3 S cm-1) in the absence of external lithium salts, a high transference number (0.84), low activation energy (0.14 eV), and a wide electrochemical stability window (0.2-5 V). We found that nonflammable, nonvolatile ionic liquid can serve as a solvating medium and excellent conductivity enhancer (>1000 times increase). These ion-conducting properties are comparable to the best polyethylene oxide-based polymer electrolytes mixed with lithium salts. Finally, we show that the solvated HCP SPE enables the reversible cycling of an all-solid-state cell prepared with a high-voltage NMC 811 cathode. Our study opens up new possibilities for developing next-generation high-performance solid-state electrolytes.