High dielectric constant and energy density achieved in sandwich-structured SrTiO₃ nanocomposite thick films by interface modulation

Abstract

The design of a sandwich structure is conducive to enhancing the dielectric constant and energy density of SrTiO3 nanocomposite thick films.

Polymer Matrix Nanocomposites with 1D Ceramic Nanofillers for Energy Storage Capacitor Applications

“…To mention some: the space charges enhance such that it assists in charge migration; fabrication defects; local electric field enhancement above the threshold breakdown strength of the surrounding matrix; the nanofillers aggregate and provide the conductive paths; and thermal runaway due to least thermal conductivity of polymer matrix material. 75,[79][80][81][82][83][84][85][86][87]93,94 Moreover, researchers often model the electric breakdown process of high dielectricfilled nanocomposites using finite element simulations, among which the well-known models are local electric field concentrations inside the nanocomposites 72,95,96 and electric field treeing through the nanocomposites. 97,98 In addition, Beale and Duxbury presented a mathematical model for the electric breakdown of nanocomposites filled with conductive particles and showed that, knowing the dimensions of nanofiller (L), its average initial breakdown strength approaches to zero when the critical exponent (p c ) becomes equal to the volume fraction of conductive nanofiller (p), follows and equation E b ≈ (p c − p) ν /ln(L).…”

“…This process is known as the avalanche breakdown. − Apart from these reasons, in the case of the dielectric nanocomposites, there are additional parameters, which assist in its early breakdown. To mention some: the space charges enhance such that it assists in charge migration; fabrication defects; local electric field enhancement above the threshold breakdown strength of the surrounding matrix; the nanofillers aggregate and provide the conductive paths; and thermal runaway due to least thermal conductivity of polymer matrix material. ,− ,, Moreover, researchers often model the electric breakdown process of high dielectric-filled nanocomposites using finite element simulations, among which the well-known models are local electric field concentrations inside the nanocomposites ,, and electric field treeing through the nanocomposites. , In addition, Beale and Duxbury presented a mathematical model for the electric breakdown of nanocomposites filled with conductive particles and showed that, knowing the dimensions of nanofiller ( L ), its average initial breakdown strength approaches to zero when the critical exponent ( p c ) becomes equal to the volume fraction of conductive nanofiller ( p ), follows and equation E b ≈ ( p c – p ) ν /ln­( L ) . In brief, the incorporation of conductive fillers decreases the electric breakdown strength of overall nanocomposites even below its percolation threshold due to the increase in conductive paths. , However, the high-dielectric-constant fillers upon their addition to polymer matrix first enhances and then reduces the overall breakdown strength of nanocomposites.…”

Excellent Energy Storage Performance in Bilayer Composites Combining Aligned TiO2 Nanoarray and Random TiO2 Nanowires with Poly(vinylidene fluoride)

“…Moreover, the dielectric loss of (x vol % TO NWs/TNA)−PVDF composites (Figure 4b) is much smaller than that of TNA−PVDF composite (Figure S2b) at low frequencies, indicating that the upper layer in the (x vol % TO NWs/TNA)−PVDF composites could greatly enhance their electric insulation and thus suppress the probability of charged carriers to reach the electrode surface. 33,44 Furthermore, the characteristic breakdown strengths of (x vol % TO NWs/TNA)−PVDF composites are fully investigated by the two-parameter Weibull distribution function, 24,45 where β represents the Weibull modulus and E b represents the breakdown strength of samples. As shown in Figure 4c, the high β values (higher than 15.0) suggest that the characteristic breakdown strengths of composites are highly reliable.…”

Significant Energy Density of Discharge and Charge–Discharge Efficiency in Ag@BNN Nanofillers-Modified Heterogeneous Sandwich Structure Nanocomposites

“…8,13,23,31−33 Besides, various nanofillers, for instance, TiO 2 , SrTiO 3 , BaTiO 3 , and BN, to name some, are incorporated with the above-mentioned matrix materials to enhance the permittivity further and to some extent diverge the electric field treeing for realizing high energy density and efficient charge−discharge cycles. 5,8,34,35 Further, the ferroelectric-type polymer nanocomposites usually show high permittivity but greater conductive losses and lower charge−discharge efficiency. 36 On the other hand, linear-type polymer nanocomposites display the least losses but lower permittivity.…”

“…From eq and eq , it can be concluded that the energy density of dielectric materials can be improved collaboratively by increasing their E b (i.e., electric breakdown strength) and D or ε r . − However, it is a dilemma that ceramic and polymer dielectric materials do not attain high energy density because of inferior E b and ε r , respectively. − To solve this problem, polymers are coupled to ceramic nanofillers for realizing nanocomposite dielectrics. This technique garnered global emphasis due to its probable application in future flexible electronic devices. ,,− Till now, several high-functioning ferroelectric-type polymers, for example, poly­(vinylidene fluoride) (i.e., PVDF), poly­(vinylidene fluoride- co -hexafluoropropylene) (i.e., PVDF-HFP), and poly­(vinylidene fluoride- co -chlorotrifluoroethylene) (i.e., PVDF-CTFE), and linear-type polymers like poly­(etherimide) and poly­(methyl methacrylate) have been utilized as polymer matrix materials. ,,,− Besides, various nanofillers, for instance, TiO 2 , SrTiO 3 , BaTiO 3 , and BN, to name some, are incorporated with the above-mentioned matrix materials to enhance the permittivity further and to some extent diverge the electric field treeing for realizing high energy density and efficient charge–discharge cycles. ,,, Further, the ferroelectric-type polymer nanocomposites usually show high permittivity but greater conductive losses and lower charge–discharge efficiency . On the other hand, linear-type polymer nanocomposites display the least losses but lower permittivity. , These limitations confine their sole use as energy storage materials for industrial applications without structural modifications.…”