摘要
为避免锂电池热失控造成的安全事故,本文将石墨烯均匀地分散在 E-44 环氧树脂基体中,以聚酰胺为固化剂将其固化成型,制备了一种具有正温度系数(Positive Temperature Coefficient,PTC)的环氧树脂/石墨烯导电复合材料,研究了石墨烯含量、固化工艺对复合材料室温电阻率的影响,并考查了复合材料的热稳定性及对LiFePO4电池热阻断性能.结果表明,石墨烯质量分数为13 wt%,E-44 环氧树脂与聚酰胺质量比为1∶0.5,固化温度为60℃,固化时间为12 h的样品,其室温电阻率为 6.48×102 Ω·cm,测试温度升高至 140℃时,复合材料电阻率升高到4.62×104 Ω·cm,PTC强度达到1.85,并具有可恢复特性.将其应用在LiFePO4电池中,发现室温下E-44环氧树脂/石墨烯复合材料的加入不会影响电池的充放电性能,当测试温度为90℃时,电池的放电比容量仅为 12.5 mAh/g,表现出优异的热阻断特性.本研究有助于推动环氧树脂基PTC导电聚合物的应用,为解决电池因热失控而引发的安全问题提供理论依据.
Abstract
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.
维普
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