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.

Improving the Ionic Conductivity and Anode Interface Compatibility of LLZO/PVDF Composite Polymer Electrolytes by Compositional Tuning

“…Their extensive electrochemical stability window and superior mechanical properties effectively prevent lithium dendrite formation, facilitating the use of lithium metal anodes with high-voltage cathodes . However, challenges persist with certain solid-state materials: ceramic electrolytes suffer from brittleness and complex processing, whereas polymer electrolytes struggle with dendrite suppression due to inadequate mechanical strength. , Composite polymer electrolytes (CPEs) emerge as a leading solution by integrating the benefits of both polymer matrices and ceramic fillers, offering improved ion conductivity, mechanical strength, and dendrite mitigation. − Among various CPEs, poly­(ethylene oxide) (PEO) systems have been extensively researched and utilized in commercial 3 V Li|PEO|LiFePO 4 batteries. − CPEs featuring PEO and active fillers like garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) showcase enhanced mechanical robustness and dendrite resistance, improving the stability of the PEO/Li metal interface. , Nonetheless, PEO’s susceptibility to oxidation above 4 V leads to challenges in accommodating high-voltage cathode materials, such as LCO and nickel-rich ternary compounds, thereby limiting the potential energy density of solid-state batteries …”