Fast Ion Conduction Nanofiber Matrix Composite Electrolyte for Dendrite-Free Solid-State Sodium-Ion Batteries with Wide Temperature Operation

Sodium-ion batteries (SIBs) based on solid-state electrolytes (SSEs), although safe for high temperatures, are less capable of transferring ions at ambient temperatures, let alone at low temperatures. This work offers a simple and scalable technique to construct a nanofiber matrix composite electrolyte with boosting Na+ transport and interfacial compatibility for SIBs. Benefitting from the salt dissociation and selective cation conduction synergistic effect of the acylamino, carbonyl, and ester groups in the low-cost copolymer synthesized from 2-(methacryloyloxy)ethyl acetoacetate and N,N '-methylenebisacrylamide, a facilitating of Na+ transport at extreme temperatures is realized. Besides, flexible flame retardance ceramic SiO2 nanofibers greatly enhance high-temperature safety. The ultrathin functional AlF3 layer generated by binder-free magnetron sputtering suppresses the dendrites, eliminating the interfacial issues between the electrolyte and anode, which is proved by 5500 h of ultrasteady plating/stripping. Superior ionic conductivity of 0.153 mS cm(-1) at -30 degrees C implies fast Na+ transport, which is further evidenced by molecular dynamics simulations. Rate performance at 0.05-10 C from -30 to 130 degrees C further demonstrates the excellent electrochemical performance of the electrolyte. This work provides encouraging guidance for high-safety SSEs with rapid Na+ conduction for SIBs operating at extra-wide temperatures.