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

Abstract

TiO2 nanoarray (TNA) is usually used to improve the energy storage performance of the polymer composite; however, owing to the paradox between polarization and breakdown strength, the discharged energy density of TNA-based composite is always restricted. In this study, a novel bilayer composite with excellent energy storage performance has been designed and fabricated by combining aligned TNA and random TiO2 nanowires (TO NWs) with poly­(vinylidene fluoride) (PVDF) matrix. Interestingly, a superior discharged energy density of 16.13 J/cm3 was obtained in the (5 vol % TO NWs/TNA)–PVDF composite, which is 2.0 times higher than that of pure PVDF matrix (8.23 J/cm3) due to the simultaneously improved polarization and breakdown strength. Additionally, the corresponding energy efficiency remains high (77.37%) owing to the nonferroelectric characteristics of the TO fillers and the suppressed leakage current density. Considering the excellent and sharply incremental discharged energy density and superior energy efficiency of the (5 vol % TO NWs/TNA)–PVDF composite, this demonstrated work provides a method to obtain high discharged energy density and energy efficiency simultaneously.

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

“…Comparison of the current work’s energy density and charge–discharge efficiency with other reported works about sandwich-structured nanocomposites, which have the charge–discharge efficiency alongside large energy density. ,,,,,,− …”

“…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.…”

Significantly Improved Energy Storage Performance of PVDF Ferroelectric Films by Blending PMMA and Filling PCBM

“…To make a more comprehensive comparison of the energy storage properties between inorganic filler/polymer matrix composites and the all-organic composite, relevant studies are shown in Figure . ,− The breakdown strength of the inorganic filler/polymer matrix composites is mostly concentrated below 550 kV mm –1 with a lower energy storage efficiency, as shown in Figure , which is greatly related to the defects generated by the introduction of inorganic fillers. The all-organic composite in this work can effectively avoid the generation of similar defects, achieve a higher breakdown strength, and maintain high efficiency, which makes it have a higher energy storage density although without a higher dielectric constant like inorganic filler/polymer matrix composites.…”

Vanadium-Substituted Dawson-Type Polyoxometalate–TiO2 Nanowire Composite Film as Advanced Cathode Material for Bifunctional Electrochromic Energy-Storage Devices

“…This result reveals that their system is a promising material for energy-storage applications. In addition, Ji et al [19] designed and fabricated a novel bilayer composite with an excellent energy-storage performance by combining an aligned TiO 2 nanoarray (TNA) and random TiO 2 nanowires (TiO 2 NWs) with a poly(vinylidene fluoride) (PVDF) matrix. A superior discharge energy density of 16.13 J cm −3 was obtained for the 5 vol% TiO 2 NW/TNA-PVDF composite, which was 2.0 times higher than that of the pure PVDF matrix (8.23 J cm −3 ).…”