Abstract: A new kind of materials having positive temperature coefficient (PTC) possessing conductance changes along with its metal-insulator phase transition were developed for use as conducting materials that can improve the safety performance of lithium-ion batteries at elevated temperatures. Contrast tests were carried out to probe at the PTC mechanism and temperature-resistance behavior of lithium-ion batteries with or without the PTC additives. Test results showed that the additives exhibit obvious PTC tendencies when the cell temperature exceeds (80 ℃,) leading to marked improvements in the thermal safety of lithium-ion batteries.