▎ 摘　　要

Polymeric positive temperature coefficient (PTC) materials can be used to install "brake" technology for the thermal runaway of lithium-ion batteries. However, it still has poor cycle stability and obvious negative temperature coefficient (NTC) effect, which reduces the reliability of the material. In order to solve these problems, conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) modified multilayer graphene (MLG) conductive additive (PEDOT-MLG) is introduced into middle density polyethylene/carbon black (MDPE/CB) system. Compared with the conventional modification, the PEDOT modified MLG shows high conductivity and excellent thermal stability. In addition, the introduction of PEDOT-MLG into MDPE/CB can further reduce the room temperature resistivity due to the good compatibility between the modified graphene and the matrix, thus improving the PTC intensity to 7.1. What is more, MLG limits the re-aggregation of CB particles when the temperature further rises, which effectively weakens the NTC effect.