Beletskii Evgenii, Ershov Valentin, Danilov Stepan, Lukyanov Daniil, Alekseeva Elena, Levin Oleg
Institute of Chemistry, St. Petersburg State University, 199034 Saint Petersburg, Russia.
Polymers (Basel). 2020 Dec 6;12(12):2925. doi: 10.3390/polym12122925.
Materials with a positive temperature coefficient have many applications, including overcharge and over-temperature protection in lithium-ion (Li-ion) batteries. The thermoresistive properties of an electrically conductive polymer, based on a Ni(salen)-type backbone, known as polyNiMeOSalen, were evaluated by means of in situ resistivity measurements. It was found that the polymer was conductive at temperatures below 220 °C; however, the polymer increased in resistivity by three orders of magnitude upon reaching 250 °C. Thermogravimetric results combined with elemental analyses revealed that the switch from the insulation stage to the conductive stage resulted from thermally dedoping the polymer. Electrochemical studies demonstrated that a polymer retains its electroactivity when it is heated and can be recovered to a conductive state through oxidation via electrochemical doping in an electrolyte solution.
具有正温度系数的材料有许多应用，包括锂离子（Li-ion）电池中的过充电和过温保护。通过原位电阻率测量评估了一种基于Ni（salen）型主链的导电聚合物（称为聚NiMeOSalen）的热阻特性。发现该聚合物在220℃以下的温度下具有导电性；然而，当达到250℃时，聚合物的电阻率增加了三个数量级。热重分析结果与元素分析相结合表明，从绝缘阶段到导电阶段的转变是由于聚合物的热去掺杂所致。电化学研究表明，聚合物在加热时保留其电活性，并且可以通过在电解质溶液中进行电化学掺杂氧化恢复到导电状态。
