Improved Energy Storage Performance in Sandwiched Poly(vinylidene fluoride)-Based Composites Assembling with In-Plane-Oriented BN Nanosheets and TiO₂ Nanowires

Abstract

With the rapid development of modern electronic and power systems, the low energy storage density is a critical weakness that greatly restricts the functional performance and application range of dielectric capacitors. Generally, the overall dielectric constant and breakdown strength are two key parameters that determine the energy storage density of a dielectric material. However, there is a significant negative coupling effect between these two parameters. Herein, a multilayer-structured composite showing an excellent energy storage performance was designed and fabricated by combining the continuous processes of spraycoating, melt mixing-extruding, in-situ dragging, alignment of oriented fibers, and hot-pressing procedures. This fabrication process has great potential in scaled production in industries. In this multilayered construction, the upper and lower layers are the PVDF thin layer deposited with in-plane oriented BN nanosheets (BNNSs), which provides a high breakdown strength for the composite. The intermediate layer is a PVDF-based composite uniformly dispersed with in-plane oriented TiO 2 nanowires (TONWs), which enhance the interfacial and dipole polarizations in composites. The synergetic contribution of good dispersion and orientation perpendicular to the electric field minimizes the occurrence probability of ohmic contact and tunneling effects between TONWs, which limits the transport of charges in the intermediate polarized layer, increases the dielectric constant, and avoids the premature breakdown of composites. Under the extremely low filler loadings (BNNSs and TONWs are 0.11 and 1 wt % in the outer and middle layers, respectively), both the significantly enhanced excellent discharge energy density of 6.67 J/cm 3 and breakdown strength of 376 MV/m were achieved from the BNNS/TONW/PVDF sandwich composite, which were 340 and 156% greater than those of the pure PVDF matrix (1.96 J/cm 3 and 240 MV/m) respectively. This work provides an effective and feasible strategy for the enhancement of both energy storage density and scaled-production potential of polymer-based composite dielectrics.

Multi-layered medium ultrasonic phased array sparse TFM imaging based on self-adaptive differential evolution algorithm

“…each material while compensating for their shortcomings. This type of structure is widely utilized across multiple fields, including aerospace [1], automotive industry [2], construction [3], energy [4], and medical devices [5], among others. However, due to the complex manufacturing processes, voids and cracks are commonly found within these products, which are not permissible in practical applications.…”

Enhanced Energy Storage Density of Ferroelectric Polymer-Based Composite Dielectrics via Introducing Surface-Charged Kaolin Nanosheets

“…Based on this challenge, in recent years, more and more researchers have shifted their research focus to impede the decrease or even to enhance the E b of composite dielectrics. The useful strategies are mainly as follows: (i) constructing core–shell-structured nanofillers, which is helpful in relieving the electric field distortion and localized electric field concentration at the matrix–fillers interface, caused by the large ε r difference between the high-ε r inorganic filler phase and low-ε r polymer matrix phase; − (ii) using nanofillers with high aspect ratios to optimize the filler dispersion while scattering free charges that are concentrated along the direction of the applied electric field; − (iii) constructing heterogeneous multilayer composite dielectrics, where the development of the electrical tree can be hindered by the interfacial blocking effect between neighboring layers; − and (iv) utilizing two-dimensional (2D) nanosheets with broad forbidden bands as functional nanofillers in combination with appropriate orientation processes to impede the development of free charges along the direction of the electric field. − …”

Achieving Excellent Dielectric and Energy Storage Performance in Core-Double-Shell-Structured Polyetherimide Nanocomposites

“…Two primary methodologies are employed in the fabrication of high-performance dielectric composites. The first approach involves the incorporation of ferroelectric ceramics possessing high dielectric constants, such as barium titanate (BaTiO 3 ) [ 13 , 14 ], strontium titanate (SrTiO 3 ) [ 15 , 16 , 17 ], titanium dioxide (TiO 2 ) [ 18 , 19 ], and copper calcium titanate (CCTO) [ 20 , 21 ] into polymers. However, this method often necessitates a substantial filler content, thereby potentially compromising the mechanical properties of the composite.…”