Multipolar Conjugated Polymer Framework Derived Ionic Sieves via Electronic Modulation for Long‐Life All‐Solid‐State Li Batteries

Abstract

Here, we build a tunable multipolar conjugated polymer framework platform via pore wall chemistry to probe the role of electronic structure engineering in improving the Li+ conduction by theoretical studies. Guided by theoretical prediction, we develop a new cyano‐vinylene‐linked multipolar polymer framework namely CNF‐COF, acting as efficient ion sieves to modify polymer electrolytes for long‐lifespan all‐solid‐state (ASS) Li metal batteries. The cyano and fluorine groups dual‐decoration in CNF‐COF favorably regulates the electronic structure via multipolar donor‐acceptor electronic effects to afford proper energy band structure and abundant electron‐rich sites for enhanced anti‐oxidative ability, facilitated ion‐pair dissociation and suppressed anion movements. Thus, the CNF‐COF incorporation into poly (ethylene oxide) (PEO) electrolytes not only renders selective rapid Li+ conduction but also facilitates the Li dendrite suppression. Specifically, the constructed composite electrolyte with an ultralow CNF‐COF content of only 0.5 wt% is endowed with a high ionic conductivity of 0.634 mS cm‐1 at 60 °C and a large Li+ transference number of 0.81. As such, the Li symmetric cell delivers stable Li plating/stripping over 1400 h. Impressively, t he assembled ASS Li battery under 60 °C allows for stable cycling over 2000 cycles at 1 C and over 1000 cycles even at 2 C.