Study on the Thermal Blocking Characteristic of E-44 Expoxy Resin/graphene Composites
To avoid safety accidents caused by thermal runaway of lithium batteries,graphene was uniformly dispersed in the E-44 epoxy resin matrix and cured with polyamide as a curing agent to prepare an epoxy/graphene conductive composite material with positive temperature coefficient(PTC)in this study.The effects of graphene content and curing process on the room temperature resistivity of the composite were investigated.Furthermore,the thermal stability and thermal blocking performance of the composite for LiFePO4 batteries was also examined.The results showed that the sample with a graphene mass fraction of 13 wt%,an E-44 epoxy resin to polyamide mass ratio of 1∶0.5,a curing temperature of 60℃,and a curing time of 12 h had a room temperature resistivity of 6.48×102 Ω·cm.When the test temperature was increased to 140℃,the composite material's resistivity increased to 4.62×104 Ω·cm,with a PTC strength of 1.85 and recoverable characteristics.When applied to LiFePO4 batteries,it was found that the addition of E-44 epoxy resin/graphene composite material at room temperature did not affect the charge and discharge performance of the battery.When tested at 90℃,the specific discharge capacity of the battery is only 12.5 mAh/g,demonstrating excellent thermal blocking characteristics.This study will help promote the application of epoxy resin-based PTC conductive polymers and provide a theoretical basis for solving safety issues caused by thermal runaway in batteries.
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