IMPEDANCE STUDIES FOR SEPARATORS IN RECHARGEABLE LITHIUM BATTERIES

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 bat teries during electrical abuse. For this reason, a separator can act a s 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-degrees-C can be used to determine these parameters.