1D/2D Carbon Nanomaterial‐Polymer Dielectric Composites with High Permittivity for Power Energy Storage Applications

J of Applied Polymer Sci

Liu

et al. 2019

Flexible dielectric materials with high electric energy density and high‐temperature resistant characteristic are of great importance for modern electronics and electrical systems. Herein, two‐dimensional molybdenum disulfide (MoS2) nanosheets were efficiently produced via liquid‐phase exfoliation and then incorporated into polyimide (PI) to prepare MoS2/PI dielectric nanocomposites. Compared to the pristine PI, MoS2/PI nanocomposite films exhibited much larger dielectric permittivity while their dielectric losses still maintained relatively low levels. On the other hand, the Weibull breakdown strength of these nanocomposite films initially increased and then decreased with the increase in the MoS2 content and gave rise to a maximum value of 395 MV m−1 at 1 vol % loading. Combination of the improved dielectric permittivity and breakdown strength makes the MoS2/PI nanocomposite film with 1 vol % MoS2 possess an elevated energy density of about 3.35 J cm−3. Moreover, good tensile and thermal properties of the nanocomposite films hold great promise for their applications in high‐temperature and harsh conditions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47991.

Section: Introductionmentioning

confidence: 99%

Dielectric properties and energy‐storage performance of two‐dimensional molybdenum disulfide nanosheets/polyimide composite films

Cheng

J of Applied Polymer Sci

Liu

et al. 2019

“…In recent years, enormous attention and research enthusiasm have been devoted to high dielectric (high-k) materials for their wide applications in actuators [1,2], antennas [3], capacitors [4][5][6][7], wave-transparent (or absorbing) devices [8][9][10][11][12][13], and other electronic devices [14][15][16][17][18][19][20][21][22]. Most conventional highk materials are ceramic or ceramic composites, but their applications are seriously restricted by their intrinsic frangibility, high density, poor plasticity, and low breakdown strength.…”

Section: Introductionmentioning

confidence: 99%

Improved dielectric permittivity and retained low loss in layer-structured films via controlling interfaces

Mao

Shi

Adv Compos Hybrid Mater

et al. 2018

The search for high-performance dielectric materials has long been driven by the urgent needs for various modern electronics. However, enhanced permittivity is always accompanied by elevated loss, which seriously hinders the development and applications of dielectric materials. Herein, negative-k layers were introduced into layer-structured films, forming a new class of multilayer composites consisting of alternately stacked positive-k and negative-k layers. Compared with traditional multilayer composites without negative-k layers, the layered composites containing extra positive-k/negative-k interfaces exhibit superior ability in balancing the contradict parameters: permittivity and loss, yielding substantially enhanced permittivity without sacrificing the low loss. It is indicated that the permittivity was enhanced by the charge accumulations and reinforced polarizations on the interfaces between positive-k and negative-k layers. Meanwhile, the loss induced by the leakage current was suppressed by the blocked transport of carriers between adjacent layers. The trilayered 60-3.5-60 composite exhibits an enhanced dielectric constant (ε′ ≈ 33 @10 kHz) and retained low loss (tanδ ≈ 0.12 @10 kHz) compared with the single-layer BT/PVA composite containing 60 wt% BT fillers (ε′ ≈ 9.5 @10 kHz, tanδ ≈ 0.075 @10 kHz). This research offers an effective way to design and fabricate novel high-performance dielectric materials.

“…For example, owing to the high level of breakdown strength ( E b ), the polymer solid insulation dielectrics56 (e.g. PVDF copolymers378 and associated composite materials9101112) have been triggering tremendous research interests on achieving large energy density in the high electric field region ( E ≈ 6000 kV/cm) 3 . However, the raising up of electric field strength is challenging the supporting insulation system, which may limit its applications on miniaturized equipments and portable or wearable electronic devices with high level of integration.…”

mentioning

confidence: 99%

Enhancing dielectric permittivity for energy-storage devices through tricritical phenomenon

Gao

Liu

et al. 2017

Sci Rep

105

Although dielectric energy-storing devices are frequently used in high voltage level, the fast growing on the portable and wearable electronics have been increasing the demand on the energy-storing devices at finite electric field strength. This paper proposes an approach on enhancing energy density under low electric field through compositionally inducing tricriticality in Ba(Ti,Sn)O3 ferroelectric material system with enlarged dielectric response. The optimal dielectric permittivity at tricritical point can reach to εr = 5.4 × 104, and the associated energy density goes to around 30 mJ/cm3 at the electric field of 10 kV/cm, which exceeds most of the selected ferroelectric materials at the same field strength. The microstructure nature for such a tricritical behavior shows polarization inhomogeneity in nanometeric scale, which indicates a large polarizability under external electric field. Further phenomenological Landau modeling suggests that large dielectric permittivity and energy density can be ascribed to the vanishing of energy barrier for polarization altering caused by tricriticality. Our results may shed light on developing energy-storing dielectrics with large permittivity and energy density at low electric field.