Amino‐functionalized SiO ₂ modified porous polyetherimide separator for high performance Li‐S batteries

Abstract

As one of the most promising energy storage systems, the application of lithium sulfur battery is hindered by low ionic conductivity, poor thermal stability, and a serious shuttle effect of polysulfide species of commercial polyolefin separators. Herein, a kind of novel porous polyetherimide (PEI) based separator (IAPEI-4) with excellent heat resistance and electrochemical properties was prepared. Briefly, by grafting amino group (-NH 2 ) onto the surface of SiO 2 , highly dispersed amino-functionalized SiO 2 (A-SiO 2 ) were synthesized as fillers to blend PEI matrix. Based on physical characterizations of the representative IAPEI-4 separator, abundant micropores and mesopores exist in the separator, and A-SiO 2 nanoparticles are uniformly distributed in the PEI matrix. The ameliorated Li + transport channels and the uniform distribution of A-SiO 2 nanoparticles endow IAPEI-4 separator with higher ionic conductivity (1.60 mS cm À1 ) and Li + transfer number (0.63). Besides, the IAPEI-4 separator exhibits good electrochemical stability and excellent thermal stability (no shrinkage at 200 C). The Li-S cells with the IAPEI separator also show greatly enhanced electrochemical performances. After 100 cycles, its specific discharge capacity can reach 695.4 mAh g À1 at 0.2 C and its capacity retention rate is 84.8%. This simple and effective separator modification method can provide a general strategy to achieve high-performance Li-S batteries.

A Light-Thin Chitosan Nanofiber Separator for High-Performance Lithium-Ion Batteries

“…The calculations showed that the binding energy of -NH2 and PF 6 .was 4.27 eV, which was stronger than that of other natural materials, such as cellulose and chitin [30,36]. This indicates that -NH2 limits the migration of anions in liquid electrolyte, thereby allowing relatively easier Li + transport [33]. Separators as inactive components in LIBs should have good electrochemical stability within a wide voltage range.…”

“…To improve Li + transport in natural biomass nanofiber-based separators, the porosity and pore structure can be adjusted by using a pore former during the formation. However, the reported pore formers such as nano-silica particles may result in an increase in the weight of the separator [33]. To address this issue, researchers tend to change the diameters of the fibers to adjust the porosity and pore size of the separators.…”