核-壳结构纳米填料/聚偏二氟乙烯复合电介质的制备及储能性能

Preparation and Energy Storage Performance of Core-Shell Nanofiller/Polyvinylidene Fluoride Composite Dielectrics

在薄膜电容器领域,开发高储能密度(U)和高放电能量效率(η)的聚合物复合电介质仍然是一大挑战。文中将银纳米粒子(AgNP)负载到钛酸钡(BT)纳米颗粒上,再将其表面改性制得被二氧化硅(SiO_(2))壳层包覆的负载AgNP的BT纳米填料(SiO_(2)@Ag@BT)。AgNP赋予材料较大的电位移,而绝缘的SiO_(2)壳层充当缓冲层限制了漏电流,防止了材料的电击穿及空间电荷的渗透。当SiO_(2)@Ag@BT质量分数为3%时,聚偏二氟乙烯(PVDF)纳米复合电介质的介电常数为10.0,介电损耗(tanδ)低至0.024,击穿场强为329 MV/m。在200 MV/m的电场下,与BT/PVDF相比,SiO_(2)@Ag@BT/PVDF纳米复合电介质的储能密度提高了13.7%,达到2.72 J/cm3,且放电能量效率达到78.0%。经SiO_(2)改性的含AgNP核-壳结构填料在低添加量下即可实现聚合物复合电介质储能密度的提高并保持高放电能量效率,这为设计新型聚合物电介质材料提供了一种简单而有效的思路。

It is still a great challenge to develop high performance polymer nanocomposite dielectrics with high energy storage density(U)and high discharged energy efficiency(η).In the current study,a core-shell structured nanofiller(i.e.,SiO_(2)@Ag@BT)was fabricated by loading silver nanoparticles(AgNP)onto the surface of barium titanate(BT)nanoparticles,followed by surface coating of insulating silica(SiO_(2))layer.AgNP endowed relatively high electrical displacement to the as-prepared dielectrics.Furthermore,the insulating SiO_(2) shell acted as buffer layer to restrict leakage current and prevent electrical breakdown and the penetration of space charges.As a result,polyvinylidene fluoride(PVDF)nanocomposite dielectrics exhibit a dielectric constant of 10.0 and a low dielectric loss(tanδ)of 0.024,and breakdown strength of 329 MV/m at a SiO_(2)@Ag@BT loading of 3%.Under an electric field of 200 MV/m,the U of SiO_(2)@Ag@BT/PVDF nanocomposite dielectrics is 2.72 J/cm3,which is 13.7%higher than that of BT/PVDF nanocomposite dielectrics.Andηis as high as 78.0%.The core-shell structured nanofiller containing AgNP and SiO_(2) buffer layer could increase the U of polymer nanocomposite dielectrics at a low content and maintain the highη,which provides a simple and effective way to design new polymer nanocomposite dielectrics.