Nonflammable and thermally stable glass fiber/polyacrylate (GFP) separator for lithium-ion batteries with enhanced safety and lifespan

Abstract

The thermal stability and electrolyte wettability of commercial polyolefin separators cannot support the safety and electrochemical performance of lithium-ion batteries (LIBs) under some limiting conditions. In this work, polyacrylate is dispersed into glass fibers by immersion, and then, a glass fiber/polyacrylate (GFP) separator is obtained after the rolling and drying process. Compared with the polyolefin (PE) separator, the GFP separator shows enhanced thermal stability, electrolyte wettability, ionic conductivity, and liquid absorption ability. There is almost no shrinkage of the GFP when it is annealed at 350 °C for 30 min. According to nail penetration, overcharge, and adiabatic rate calorimeter measurements using LiNi0.5Co0.2Mn0.3O2/graphite pouch cells with a nominal limited capacity of 2000 mAh, the GFP separator can effectively inhibit exothermic reactions in the batteries when the internal temperature is out of control. In addition, the adhesive property of polyacrylate can also strengthen the cell structure and inhibit expansion and deformation during cycling. The cells with the GFP separator also show enhanced capacity retention of 91% after 600 cycles at 1C. Thus, combined with its advantages in terms of price, preparation, electrochemical performance, and safety, the GFP separator exhibits promising prospects in the application of commercial LIBs.