Flexible inorganic membranes used as a high thermal safety separator for the lithium-ion battery

Abstract

A flexible SiO₂ porous fiber membrane (SF) is prepared by electrospinning followed by calcination in this work. Compared with an organic substrate separator, the SF used as a separator will be an absolute guarantee of the battery thermal safety. The porosity of the SF is 88.6%, which is more than twice that of a regular PP separator. Hydrophilic SF shows better electrolyte wetting ability and its high porosity enables the SF to absorb 633% liquid electrolyte on average, while the lithium-ion conductivity reaches 1.53 mS cm⁻¹. The linear sweep voltammogram testing of PP and SF suggested that SF, with great electrochemical stability, can meet the requirements of lithium-ion batteries. The cyclic and rate performances of batteries prepared with SF are improved significantly. Such advantages of the SF, together with its potential in mass production, make the SF a promising membrane for practical applications in secondary lithium-ion batteries.