核-壳结构界面对纳米Ag掺杂BaTiO3@PDA/P(VDF-HFP)复合膜介电和储能性能影响

为改善聚偏氟乙烯（PVDF）基复合材料界面相容性，提高其电性能，利用聚多巴胺（PDA）成功包覆了纳米钛酸钡（BaTiO₃），并引入纳米Ag离子制备出具有核-壳结构的Ag镶嵌BaTiO₃@PDA-Ag颗粒。以介电聚合物聚偏氟乙烯-六氟丙烯（P（VDF-HFP））为基体，采用溶液流延法制备了BaTiO₃@PDA-Ag/P（VDF-HFP）复合材料厚膜。利用FTIR和XPS验证了BaTiO₃@PDA-Ag/P（VDF-HFP）复合材料结构和形貌，并用宽频介电频谱仪和铁电测试仪分别比较了PDA包覆前后的不同BaTiO₃含量的BaTiO₃@PDA-Ag/P（VDF-HFP）复合膜在低电场下的介电性能和高电场下的电极化性能。结果表明，BaTiO₃@PDA-Ag质量分数为20wt%的BaTiO₃@PDA-Ag/P（VDF-HFP）复合膜在10 Hz下介电常数（ε_r）达到了25，介电损耗（tanδ）仅为0.1，在175 M·Vm-1电场下电极化强度（D_m）为6.2 μC·cm-2，200 M·Vm-1时储能密度（U_e）达到了6.9 J·cm-3，高于其它界面未处理复合膜。以上结果可为此类介电复合材料界面结构处理和电性能研究提供参考。 

Effect of core-shell structured interface on dielectric and energy storage properties of nano Ag decorated BaTiO3@PDA/P(VDF-HFP) composite films

To improve the interfacial compatibility as well as enhance the dielectric properties of polyvinylidene fluoride (PVDF) based inorganic composite, the BaTiO₃ nanoparticles were coated using Ag decorated inorganic layer polydopamine (PDA). Subsequently the BaTiO₃@PDA-Ag particle was introduced the dielectric polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)) matrix and BaTiO₃@PDA-Ag/P(VDF-HFP) composite films were prepared using a solution casting mothed. FTIR and XPS were employed to detect the structures and monographs of the BaTiO₃@PDA-Ag/P(VDF-HFP) composites, and the wide range frequency dielectric spectrometer and ferroelectric property testing system were used to compare the dielectric and polarizing properties of the BaTiO₃@PDA-Ag/P(VDF-HFP) composite films under various electric fields. In the BaTiO₃@PDA-Ag/P(VDF-HFP) composite film with 20wt% BaTiO₃@PDA-Ag particles, a high dielectric constant of 25 and low loss of 0.1, a large electric displacement of 6.2 μC·cm^-2 under 175 M·Vm^-1, and a considerable high discharging energy density of 6.9 J·cm^-3 under 200 M·Vm^-1 are obtained. Considering its favorable interface and considerable electric performances, the core-shell structure of the BaTiO₃@PDA-Ag/P(VDF-HFP) composite provides a reference to the future research of this sorts of composites for energy storage devices.