All-Organic Cross-Linked Polysiloxane-Aromatic Thiourea Dielectric Films for Electrical Energy Storage Application

Abstract

The development of high-power-density energy storage devices and systems calls for high-dielectric-constant (high-k) polymer films with low dielectric loss. Aromatic polythiourea attracts many interests because of its low dielectric loss and high beakdown strength, whereas the high brittleness significantly limits its application as dielectric films. In this report, flexible high-k films were successfully fabricated by cross-linking aromatic thiourea oligomers with allyl glycidyl ether grafted poly­(methylhydrosiloxane) (PMHS). Siloxane segments of PMHS improve the flexibility of the cross-linked dielectric films, and the grafted glycidyl ether side groups of PMHS provide highly polarizable building blocks. Because of the high dipole moment (4.89 D), aromatic thiourea endows the dielectric films with a high dielectric constant. Microphase separation morphology was found within the film, and the self-assembly into layered lamellae contributed to the scatter of high-energy-charge carriers. As a result, the dielectric films exhibit reduced dielectric loss tangent and suppressed leakage current density with a high dielectric constant of above 6, a promissing energy density of 3.15 J/cm3 and a high efficiency of above 87% under an electric field of 350 MV/m.

Research Progress of All Organic Polymer Dielectrics for Energy Storage from the Classification of Organic Structures

“…Unfortunately, PTUA film faces the issue of poor mechanical properties due to brittleness, which is extremely limited to processed into flexible capacitor films for mass production. [ 26,105 ]…”

“…Liu et al. [ 129 ] prepared a crosslinked polysiloxane‐aromatic thiourea dielectric film by crosslinking reaction between thiourea and epoxy. The high dipole moment of thiourea endows the crosslinked films with a high ε r of above 6.…”

“…However, both of them are strongly limited by their film processability and the polymer matrix properties. [ 26 ] For organic‐inorganic hybridization, the dilemma on filler amount has to be faced, since a low amount would not enhance the ε r apparently while a high amount would generally induce deterioration of breakdown strength and processability. [ 26 ] For structure design composites, the polymer matrix of each layer determines the upper limit of material modification.…”

“…[ 26 ] For organic‐inorganic hybridization, the dilemma on filler amount has to be faced, since a low amount would not enhance the ε r apparently while a high amount would generally induce deterioration of breakdown strength and processability. [ 26 ] For structure design composites, the polymer matrix of each layer determines the upper limit of material modification. Therefore, designing polymers with better performances seems critical to achieve a processable film with admirable properties.…”

Thioureas Bridged Polysiloxanes for Ultrafast Detection of Cr6+ and Applications

“…Polythiourea, as a kind of unique attractive material, has attracted wide attention due to its unique characteristics including high refractive index, high infrared transparency, metal coordination ability, and self‐healing ability. [ 1–4 ] In addition, it has important applications in the field of biomedicine because of its unique bactericidal, antiviral, and antitumor properties. [ 5–7 ] However, there are certain conditions that restricted its development dramatically.…”