Liu Hexing, Wang Jian, Wang Yunfan, Shen Zhonghui, Zhang Xin, Li Bao-Wen
State Key Laboratory of Silicate Materials for Architectures, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China.
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China.
Nanoscale. 2025 Feb 6;17(6):3507-3517. doi: 10.1039/d4nr04802d.
Polyvinylidene fluoride (PVDF) film, with high energy density and excellent mechanical properties, has drawn attention as an energy storage device. However, conduction loss in PVDF under high electric fields hinders improvement in efficiency due to electrode-limited and bulk-limited conduction. Well-aligned multilayer interfaces of two-dimensional (2D) nanocoatings can block charge injection, reducing electrode-limited conduction loss in dielectric polymers. Thus, rational selection of 2D fillers is crucial for designing high-energy-density dielectric materials. This study explores 2D oxide nanosheets with varying dielectric constants and bandgaps, such as TiO, CaNbO, and montmorillonite (MMT). CaNbO nanosheets, with a higher dielectric constant and similar bandgap to TiO, created a higher Schottky barrier (0.6 eV), resulting in a discharge energy density () of 26.4 J cm at 720 MV m in PVDF-CaNbO film. The PVDF-MMT film, coated with MMT nanosheets featuring a lower dielectric constant yet a higher bandgap, achieves a similar of 26.8 J cm at 720 MV m, with efficiencies () above 80% for both films. The results indicate that the bandgap and dielectric constant of 2D nanosheets play a crucial role in determining PVDF composites' energy storage density and efficiency, necessitating a balance between these parameters. Furthermore, ultraviolet (UV) irradiation was introduced to induce trap centers and inhibit charge conduction and energy loss in PVDF-based composites under high electric fields. Consequently, the UV-treated PVDF-MMT composite film achieves a of 29.1 J cm and an of 78.3% at 750 MV m. This work offers an effective strategy for developing high-energy density, high-efficiency PVDF-based polymer materials.
聚偏二氟乙烯（PVDF）薄膜具有高能量密度和优异的机械性能，作为一种储能装置受到了关注。然而，由于电极限制传导和体限制传导，PVDF在高电场下的传导损耗阻碍了效率的提高。二维（2D）纳米涂层的良好排列多层界面可以阻止电荷注入，减少介电聚合物中的电极限制传导损耗。因此，合理选择二维填料对于设计高能量密度介电材料至关重要。本研究探索了具有不同介电常数和带隙的二维氧化物纳米片，如TiO、CaNbO和蒙脱石（MMT）。CaNbO纳米片具有较高的介电常数和与TiO相似的带隙，形成了更高的肖特基势垒（0.6 eV），导致PVDF-CaNbO薄膜在720 MV/m时的放电能量密度（）为26.4 J/cm³。涂覆有介电常数较低但带隙较高的MMT纳米片的PVDF-MMT薄膜在720 MV/m时实现了相似的26.8 J/cm³的，两种薄膜的效率（）均高于80%。结果表明，二维纳米片的带隙和介电常数在决定PVDF复合材料的储能密度和效率方面起着关键作用，需要在这些参数之间取得平衡。此外，引入紫外线（UV）照射以诱导陷阱中心，并抑制高电场下PVDF基复合材料中的电荷传导和能量损失。因此，经紫外线处理的PVDF-MMT复合薄膜在750 MV/m时实现了29.1 J/cm³的和78.3%的。这项工作为开发高能量密度、高效率的PVDF基聚合物材料提供了一种有效策略。
