Poly(vinylidene fluoride-co-hexafluoropropylene)-MXene Nanosheet Composites for Microcapacitors

Abstract

Polymer composites with high dielectric constant (high-k) have a broad application in the energy storage field. However, the balance between high dielectric constant, low dielectric loss, and low filler content is hardly achieved. In this work, single-layered MXene nanosheets with a thickness of ∼1 nm and a lateral size of ∼560 nm were prepared by in situ hydrofluoric acid (HF) method, and MXene/poly­(vinylidene fluoride-co-hexafluoropropylene) composites were prepared by a simple solution casting method. The morphologies, crystalline behaviors, and dielectric properties of the composites were fully investigated. At 1 kHz, composites have a high dielectric constant of 539 and a low dielectric loss of 0.06 when the content of MXene is 4.0 wt%. High dielectric constant is strongly related to the enhancement of interfacial polarization and the formation of microcapacitor structure. Possible microscopic mechanisms about the role of MXene in improving the dielectric constant of composites were elucidated by means of Ag nanoparticles. Moreover, finite element modeling conducted by COMSOL Multiphysics shows that low dielectric loss is attributed to the parallel arrays of nanosheets that can inhibit the conduction of leakage current. This work brings a good inspiration for the structure design of dielectric materials.

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“…The height distribution of MXene is about 5 nm, which is equal to 4-5 layers of Ti 3 C 2 T x nanosheets stacked together (Fig. 2g, h) 54,55 . The obtained MXene sheets can be completely filtered to form an intact and smooth film due to the stacking (Fig.…”

Cooperativity of Silver Nanostructures upon Electric Power Generation in Triboelectric Polyimide Layers

“…The enhanced dielectric constant of PI film is due in large part to the fact that incorporation of the conductive fillers into nonconductive film drives to accumulate the charges at their interfaces under external fields, serving as a series of microcapacitor in the nonconductive film. [30,31] At 1 Hz corresponding to the frequency of typical mechanical stimuli in nanogenerators, the dielectric constant of the composite film is 3.20 in the presence of 0.16 mg mL À1 AgNPs, and this value increases to 5.43 with 0.35 mg mL À1 AgNRs (Figure S3, Supporting Information). It is important to note that the dielectric constant of composite films is greatly varied with the geometrical parameters of the conductive Ag fillers.…”

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“…MXene is a kind of two-dimensional (2D) transition-mental carbide, nitride, or carbonitride with the general formula of M n+1 X n T x , where M represents an early transition metal, X represents carbon or nitrogen, n = 1, 2, or 3, and T x is the surface functional groups (e.g., -OH, -O, and/or -F groups) [ 44 , 45 ]. Interestingly, MXene possesses an outstanding electronic conductivity, large surface area, and high aspect ratio, making it a great candidate to enhance the dielectric constant of the polymer [ 46 , 47 , 48 ]. More importantly, abundant polar groups on the surface of MXene greatly enhance its interactions with the polar polymer matrix.…”