In-situ crafted fast Li-ion transport networks in composite quasi-solid-state electrolytes from electrospun hybrid polymer nanofibers

Composite polymer electrolytes generally suffer from inherent agglomeration of inorganic nanofillers, high crystallinity of polymer matrix, and weak interface compatibility. In this work, quasi-solid-state gel polymer electrolytes (GPEs) were constructed by in-situ hydrolysis of tetraethoxysilane to form SiO2 clusters (inSiO2) in the electrospun hybrid nanofibers of polyacrylonitrile and polyvinylidene fluoride-co-hexafluoropropylene. The as-fabricated PHP/inSiO2 free-standing membrane possesses high porosity, good wettability, and declined crystallinity. Accordingly, the PHP/inSiO2 GPEs exhibit high ionic conductivity (1.65 x 10 3 S cm 1 ), large Li+ transfer number (0.91), and wide electrochemical stable window (5.11 V). Benefited from the enhanced mechanical strength, multiple Li-ion conducting pathways, fast ion transfer kinetics, and in-situ formed interconnected inSiO2 networks with abundant hydrogen bonds promote the uniform Li-ion deposition and weaken the concentration polarization, suppressing the Li dendrite growth. Consequently, the Li||Li cell stably cycle for over 800 h under 0.5 mA cm 2 with an overvoltage of 32.1 mV. Remarkably, the LiFePO4|PHP/inSiO2|Li full cell delivers 146.5 mAh g 1 at 0.5C, and 88.9 mAh g 1 at 25C, and gives a capacity retention of 84.3 % after 500 cycles at 1 C. The superior high-rate and long-cycling performances endow PHP/inSiO2 GPEs with promising application in the solid-state lithium metal batteries operated at ambient temperature.