Abstract
To address the limitations of piezoelectric polymers which have a low dielectric constant andto improve their dielectric and ferroelectric efficiency for energy storage applications, we designed and characterized a new hybrid composite that contains polyvinylidene fluoride as a dielectric polymer matrix combined with graphene platelets as a conductive and barium titanite as ceramic ferroelectric fillers. Different graphene/barium titanate/polyvinylidene fluoride nanocomposite films were synthesized by changing the concentration of graphene and barium titanate to explore the impact of each component and their potential synergetic effect on dielectric and ferroelectric properties of the composite. Results showed that with an increase in the barium titanate fraction, dielectric efficiency ofthe nanocomposite was improved. Among all synthesized nanocomposite films, graphene/barium titanate/polyvinylidene fluoride nanocomposite in the weight ratio of 0.15:0.5:1 exhibited thehighest dielectric constant of 199 at 40 Hz, i.e., 15 fold greater than that of neat polyvinylidene fluoride film at the same frequency, and possessed a low loss tangent of 0.6. However, AC conductivity and ferroelectric properties of graphene/barium titanate/polyvinylidene fluoride nanocomposite films were enhanced with an increase in the graphene weight fraction. Graphene/barium titanate/polyvinylidene fluoride nanocomposite films with a weight ratio of 0.2:0.1:1 possessed a high AC conductivity of 1.2 × 10−4 S/m at 40 Hz. While remanent polarization, coercive field, and loop area of the same sample were 0.9 μC/cm2, 9.78 kV/cm, and 24.5 μC/cm2·V, respectively. Our results showed that a combination of graphene and ferroelectric ceramic additives are an excellent approach to significantly advance the performance of dielectric and ferroelectric properties of piezoelectric polymers for broad applications including energy storage.
Highlights
Dielectric and piezoelectric polymer materials have attracted significant attention to replace piezoelectric ceramic materials used in various applications such as medical, automotive industry, and consumer electronics dueto their lightweight, flexibility, low-cost and low-acoustic impedance, and high piezoelectric constant [1,2,3]
We present the use of graphene as a conducting element to design three-phase graphene/barium titanate/polyvinylidene fluoride (G/BT/Polyvinylidene fluoride (PVDF)) nanocomposites with high ε0, low tanδ, and enhanced ferroelectric properties and explore performance for energy storage and capacitors applications
FESEM images show that graphene sheets are not well connected; rather these are segregated by BT nanoparticles and PVDF matrix
Summary
Dielectric and piezoelectric polymer materials have attracted significant attention to replace piezoelectric ceramic materials used in various applications such as medical, automotive industry, and consumer electronics dueto their lightweight, flexibility, low-cost and low-acoustic impedance, and high piezoelectric constant [1,2,3]. An ideal dielectric material for these applications must possess high dielectric constant (ε0 ), lowenergy dissipation (tanδ), low dielectric loss (ε00 ), and high mechanical strength which are possible to achieve with polymer materials which are mechanically stable, flexible, and easy to process and make devices. The limitation of piezoelectric polymers is a low ε0 , usually less than 10, which is not ideal for capacitor applications. To overcome this limitation, a number ofceramic polymer composites were explored as dielectric fillers in different energy storage devices. Rao et al synthesized a ceramic polymer composite containing lead magnesium niobite-lead titanate/barium titanate (PMN-PT/BaTiO3 ) embedded in modified epoxy.
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