Thermally-stable and flame-retardant metal-organic framework-based separator for high-performance lithium-ion batteries

Abstract

Safety hazards hinder the development of lithium-ion batteries (LIBs), in which the failure of separator is a key point. However, commercial polyolefin separators display poor thermal stability and flame-retardant property. Aramid nanofiber (ANF) is a promising material for safer separators in batteries due to its excellent thermal stability and remarkable flame retardancy, but the pure ANF separator often shows low ionic conductivity because of the tightly packed fibers. Metal-organic framework (MOF) is a promising candidate for increasing the porosity and ionic conductivity of ANF separator due to its ultrahigh porosity and ultrahigh specific area. Herein, a thermally-stable and high-performance composite separator is fabricated by combining MOF pore-forming agent and ANF network skeleton. The MOF/ANF1composite separator with 10 wt% ANF shows excellent thermal-stability (melting-point above 300 °C and decomposition temperature above 500 °C) and remarkable flame-retardant property. And it exhibits high ionic-conductivity of 1.01 mS·cm−1, contributed to the superior long-term cycling performance of the coin cell with the capacity of 147.3 mAh·g−1 after 200 cycles at 1 C, almost 25.4 % higher than that of the coin cell with PP separator for LIBs. The strategy of this research provides new ideas for the design of high-safety LIBs.