Significant improvements in energy density and efficiency of CQDs/PVDF-based dielectric nanocomposite via stretching effect

作者：Fan Wang, Xun Jiang, Ru Guo, Hang Luo, Weifeng Wei, Dou Zhang · 发表于：Journal of Energy Storage · 年份：2024 · DOI：10.1016/j.est.2024.115027 · 被引用次数：7 · 研究领域：Dielectric materials and actuators、Advanced Sensor and Energy Harvesting Materials、Ferroelectric and Piezoelectric Materials

With the advancement towards lightweight, integrated, and intelligent capacitors, there is an urgent need to develop flexible dielectric materials with high power density and high energy storage performance. Poly(vinylidene fluoride) (PVDF) based nanocomposite has garnered widespread attention due to its high polarization and ease of processing. However, the inverse relationship between the dielectric constant and breakdown strength constrains its potential for achieving high energy density . Herein, a two-pronged approach effectively combining the incorporation of organic carbon quantum dots (CQDs) nanofiller and PVDF polymer crystallization behavior modulation is utilized to boost the energy density of nanocomposites. Particularly, CQDs increase the crystallinity and decrease the leakage current density of the nanocomposites effectively, resulting in enhanced breakdown strength. Moreover, through optimizing process parameters of stretching temperatures and rate during uniaxial stretching, significantly higher crystallinity , polar phase transition, increased chain orientation, and smoother surface are achieved to construct a denser and more stable microstructure that effectively hinders the formation of electrical breakdown pathways, thereby enhancing the electric polarization and breakdown strength of the nanocomposites. As a consequence, the ultrahigh discharge energy density of 30.8 J/cm 3 with an efficiency of 74.1 % was yielded at 944.2 kV/mm, representing improvements...