WO3-composited polyimide nanofibrous separator with superior mechanical properties and high capacity for lithium-ion batteries

The separator is an essential component of lithium-ion batteries (LIBs), and polyimide (PI), a high-performance polymer with outstanding mechanical and thermal properties and a strong electrolyte affinity, has received substantial research as a potential separator material. In this work, we fabricated a PI composite separator (PI/WO3) by combining the components in one step with concurrently electrospinning the precursor solution and electrospraying the WO3 nanoparticles. The one step mixing method made the WO3 uniformly distribute on the PI nanofiber surfaces with a result of porosity decrease. Although the introduction of WO3 nanoparticles did not alter the chemical structure and the excellent thermal stability, the electrolyte wettability, mechanical strength and electrochemical performance of PI separator were all significantly improved by the nanoparticles, endowing the composite separator with superior cycle stability. Therefore, the use of WO3 in a polyimide separator has practical significance for high safety and high performance of LIBs.