Abstract: The thermal runaway caused by the abuse of lithium batteries is one of the main reasons for battery safety accidents and a key issue that urgently needs to be addressed.In this article, E-51 epoxy resin/graphene composite with a positive temperature coefficient (PTC) was prepared by using the E-51 epoxy resin as the matrix, graphene nanosheets as the conductive fillers and polyamide as the curing agent, respectively.The effects of conductive filler graphene content and curing process on the room temperature resistivity of the composite material is investigated.Meanwhile, the recoverability and thermal blocking performance of the composite material for lithium batteries is also studied.The results showed that when the mass fraction of graphene in the composite material was 15 wt%, the curing temperature was 60 ℃, and the curing time was 3 hours, the surface resistivity at room temperature was 88 Ω·cm for the E-51 epoxy rein/graphene composite.When the test temperature was raised to 130 ℃, the PTC strength of the composite material reached 1.6 and possessed recoverability.Applying the E-51 epoxy resin/graphene composite in the LiFePO₄ batteries, the discharge time of the batteries was shortened from 70 min to 38 min at 60 ℃, which exhibiting excellent self-excited thermal blocking phenomenon.This study contributes to promoting the application of epoxy resin based PTC composite materials and provides a reference for solving safety accidents caused by thermal runaway in batteries.