Polymerization behaviour of butyl bis(hydroxymethyl)phosphine oxide: Phosphorus containing polyethers for Li-ion conductivity

Abstract

Synthesis of phosphorus containing polyethers and their lithium-ion conductivities for the potential use as solid polymer electrolyte (SPE) in high-energy density lithium-ion batteries have been described. Co-polymerization of butyl bis(hydroxymethyl)phosphine oxide with three different dibromo monomers were carried out to produce three novel phosphorous containing polyethers (P1–P3). These polymers were obtained via nucleophilic substitution reactions and were characterized by 1H, 31P NMR spectral data and gel permeation chromatography. SPEs were prepared using polyethers (P1 and P2) with various amounts of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The lithium-ion conductivity of SPE2 containing 40 wt% of LiTFSI was 2.1 × 10−5 S cm−1 at room temperature and 3.7 × 10−4 S cm−1 at 80°C. Solid polymer electrolytes having good ionic conductivity and possible flame retardant property for application in larger lithium-ion batteries were prepared using phosphorus containing polyethers wherein phosphorus atoms are present in the main polymer chain.