An enhanced poly(vinylidene fluoride) matrix separator with TEOS for good performance lithium-ion batteries

Abstract

The low crystallinity poly(vinylidene fluoride)/tetraethyl orthosilicate silane (PVDF/TEOS) composite separator with a finger-like pore structure for lithium-ion battery has been successfully prepared by non-solvent-induced phase separation (NIPS) technique. The PVDF/TEOS composite separator shows the excellent wettability and electrolyte retention properties compared with Celgard 2320 separator. AC impedance spectroscopy results indicate that the novel PVDF/TEOS composite separator has ion conductivity of 1.22 mS cm−1 at 25 °C, higher than that of Celgard 2320 separator (0.88 mS cm−1). The lithium-ion transference number of PVDF composite separator added 0.7% TEOS was 0.481, better than that of Celgard 2400 (0.332). What is more, the lithium-ion batteries assembled with PVDF/TEOS composite separator show good cycling performance and rate capability.