Impedance Studies for Separators in Rechargeable Lithium Batteries

Abstract

Melting of separators, causing closure of separator pores, will result in a strong reduction in current flow. When this process is initiated at the appropriate time it can prevent thermal runaway of lithium batteries during electrical abuse. For this reason, a separator can act as an internal safety device. The effectiveness depends on a number of separator parameters such as melting temperature, rate of pore fusion, and dimensional stability temperature. Measurement of the electrical impedance of electrolyte‐filled separators and separator combinations in the temperature range from room temperature to 200°C can be used to determine these parameters.