Zhang Tao, Dan Zhenkang, Shen Zhonghui, Jiang Jianyong, Guo Mengfan, Chen Bin, Lin Yuanhua, Nan Ce-Wen, Shen Yang
School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University Beijing 100084 China
RSC Adv. 2020 Feb 6;10(10):5886-5893. doi: 10.1039/c9ra10030j. eCollection 2020 Feb 4.
Poly(vinylidene fluoride) (PVDF)-based polymers with excellent flexibility and relatively high permittivity are desirable compared to the traditional bulk ceramic in dielectric material applications. However, the low discharge efficiency (<70%) caused by the severe intrinsic dielectric loss of these polymers result in a decrease in their breakdown strength and other problems, which limit their widespread applications. To address these outstanding issues, herein, we used a stacking method to combine poly(methyl methacrylate) (PMMA) with poly(vinylidene fluoride--hexafluoropropylene) (P(VDF-HFP)) for the synthesis of a series of alternating multilayer films with different layers. Benefitting from the blocking effect of the multilayer structure and excellent insulation performance of PMMA, simultaneous improvements in the breakdown strength and discharge efficiency of the multilayer films were achieved. Compared with the pure polymer films and other multilayer films with different layers, the film with a 9-layer structure exhibited the highest energy storage density of 25.3 J cm and extremely high discharge efficiency of 84% at 728 MV m. Moreover, the charge and discharge performance of the other multilayer films were also better than that of P(VDF-HFP). In addition, it was also found that for the multilayer composite films with the same components, the blocking effect was reinforced with an increase in the number of layers, which led to a significant improvement in the breakdown strength. We consider that the multilayer structure can correlate with the dielectric properties of different polymer materials to enhance the energy storage of composite materials, and will provide a promising route to design high dielectric performance devices.
与传统块状陶瓷相比，具有优异柔韧性和相对较高介电常数的聚偏二氟乙烯（PVDF）基聚合物在介电材料应用中更具优势。然而，这些聚合物严重的固有介电损耗导致其放电效率较低（<70%），进而导致其击穿强度降低以及出现其他问题，这限制了它们的广泛应用。为了解决这些突出问题，在此我们采用堆叠方法将聚甲基丙烯酸甲酯（PMMA）与聚（偏二氟乙烯 - 六氟丙烯）（P(VDF - HFP)）结合，以合成一系列具有不同层数的交替多层膜。受益于多层结构的阻挡效应和PMMA优异的绝缘性能，多层膜的击穿强度和放电效率同时得到了提高。与纯聚合物膜和其他不同层数的多层膜相比，具有9层结构的膜在728 MV/m下表现出最高的储能密度25.3 J/cm³和极高的84%的放电效率。此外，其他多层膜的充放电性能也优于P(VDF - HFP)。此外，还发现对于具有相同组分的多层复合膜，随着层数的增加，阻挡效应增强，这导致击穿强度显著提高。我们认为多层结构可以与不同聚合物材料的介电性能相关联，以增强复合材料的储能能力，并将为设计高介电性能器件提供一条有前景的途径。
