Agbabiaka Okikiola Ganiu, Adegun Miracle Hope, Chan Kit-Ying, Zhang Heng, Shen Xi, Kim Jang-Kyo
Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
Department of Aeronautical and Aviation Engineering, Hong Kong Polytechnic University, Hong Kong, China.
Nanomaterials (Basel). 2022 Dec 19;12(24):4492. doi: 10.3390/nano12244492.
The increasing demand for high energy storage devices calls for concurrently enhanced dielectric constants and reduced dielectric losses of polymer dielectrics. In this work, we rationally design dielectric composites comprising aligned 2D nanofillers of reduced graphene oxide (rGO) and boron nitride nanosheets (BNNS) in a polyvinylidene fluoride (PVDF) matrix through a novel press-and-fold technique. Both nanofillers play different yet complementary roles: while rGO is designed to enhance the dielectric constant through charge accumulation at the interfaces with polymer, BNNS suppress the dielectric loss by preventing the mobility of free electrons. The microlaminate containing eight layers each of rGO/PVDF and BNNS/PVDF films exhibits remarkable dielectric performance with a dielectric constant of 147 and an ultralow dielectric loss of 0.075, due to the synergistic effect arising from the alternatingly electrically conductive and insulating films. Consequently, a maximum energy density of 3.5 J/cm-about 18 times the bilayer composite counterpart-is realized. The high thermal conductivities of both nanofillers and their alignment endow the microlaminate with an excellent in-plane thermal conductivity of 6.53 WmK, potentially useful for multifunctional applications. This work offers a simple but effective approach to fabricating a composite for high dielectric energy storage using two different 2D nanofillers.
对高储能设备日益增长的需求要求同时提高聚合物电介质的介电常数并降低其介电损耗。在这项工作中，我们通过一种新颖的压制和折叠技术，合理设计了在聚偏氟乙烯（PVDF）基体中包含取向的二维还原氧化石墨烯（rGO）纳米填料和氮化硼纳米片（BNNS）的介电复合材料。两种纳米填料发挥着不同但互补的作用：rGO旨在通过与聚合物界面处的电荷积累来提高介电常数，而BNNS则通过阻止自由电子的移动来抑制介电损耗。由八层rGO/PVDF和BNNS/PVDF薄膜交替组成的微层压板表现出卓越的介电性能，介电常数为147，介电损耗超低，仅为0.075，这归因于交替排列的导电和绝缘薄膜产生的协同效应。因此，实现了3.5 J/cm³的最大能量密度，约为双层复合对应物的18倍。两种纳米填料的高导热率及其取向赋予微层压板6.53 Wm⁻¹K的优异面内热导率，这对多功能应用具有潜在的用途。这项工作提供了一种简单而有效的方法，用于使用两种不同的二维纳米填料制造用于高介电储能的复合材料。
