Bendable Network Built with Ultralong Silica Nanowires as a Stable Separator for High-Safety and High-Power Lithium-Metal Batteries

Separators are key safety components for electrochemical energy storage systems. However, the intrinsic poor wettability with electrolyte and low thermal stability of commercial polyolefin separators cannot meet the requirements of the ever-expanding market for high-power, high-energy, and high-safety power systems, such as lithium-metal, lithium-sulfur, and lithium-ion batteries. In this study, scalable bendable networks built with ultralong silica nanowires (SNs) are developed as stable separators for both high-safety and high-power lithium-metal batteries. The three-dimensional porous nature (porosity of 73%) and the polar surface of the obtained SNs separators endue a much better electrolyte wettability, larger electrolyte uptake ratio (325%), higher electrolyte retention ratio (63%), and ∼7 times higher ionic conductivity than that of commercial polypropylene (PP) separators. Moreover, the pore-rich structure of the SNs separator can aid in evenly distributing lithium and, in turn, suppress the uncontrollable growth of lithium dendrites to a certain degree. Furthermore, the pure inorganic structure endows the SNs separators with excellent chemical and electrochemical stabilities even at elevated temperatures, as well as excellent thermal stability up to 700 °C. This work underpins the utilization of SNs separators as a rational choice for developing high-performance batteries with a metallic lithium anode.