High Performance Capacitors Using BaTiO₃ Nanowires Engineered by Rigid Liquid-crystalline Polymers

Abstract

Capacitors that provide high power density have attracted scientific and commercial interest, while often suffering from low energy density. Preparing a core−shell structured ceramic is regarded as a kind of effective method to improve the energy density, which is largely determined by the shell in the interfacial region. However, the current state-of-the-art of interfacial layer modification is predominantly based on utilizing flexible polymers, which are random polymer coils that collapse on the surface of any modified ceramic nanoparticles. Because of the characteristic properties of rigidity and orientation, the liquid-crystalline polymer poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PMPCS) is utilized to engineer the interfacial layer thickness on BaTiO 3 nanowire surfaces via surface-initiated reversible addition−fragmentation chain transfer polymerization (RAFT) method, in this paper. As a result, a high discharged energy density of 7.5 J/cm 3 and an energy efficiency of 55.1% at 300 MV/m are achieved, respectively. The findings proved that rigid liquid-crystalline polymer is a promising modifier to prepare high performance capacitors and to explore the interfacial effect in dielectric nanocomposites.

Enhanced Energy Storage Characteristics in PVDF-Based Nanodielectrics With Core-Shell Structured and Optimized Shape Fillers

“…4 (c) for easier observation. The permittivity increased with increasing volume fraction, which is consistent with previous results [30]- [32]. Additionally, the results showed that the PDA-SiO 2 @BT NFs/PVDF had a higher permittivity and a lower dielectric loss than the PDA-SiO 2 @BT NPs/PVDF, which may be attributed to the larger crystalline regions in the disordered one-dimensional fibrous fillers.…”

Enhanced energy density of PVDF-based nanocomposites via a core–shell strategy

“…Thus, the breakdown strength and relative permittivity are important parameters to achieve high energy density. Among several available dielectric materials, ceramic/polymer nanocomposites (NCs) have attracted significant attention as they combine the advantages of ceramic fillers (high permittivity) and the polymer matrix (high breakdown strength, low dielectric loss, flexibility, and low cost) 11 , 17 – 19 . However, high content of ceramic particles, usually over 50 vol%, is needed to realize of a high enough permittivity in NCs, resulting in low breakdown strength.…”

“…Dielectric capacitors with the ultrafast charging and discharging speeds, high power density and low cost are very attractive materials for the potential applications in the pulsed power electronic devices, such as radars, lasers, rail guns, and medical defibrillators [1][2][3][4][5][6][7] . However, the dielectric capacitors have lower energy density than batteries, fuel cells, and double-layer supercapacitors so this type of energy storage device is still expensive and bulky [8][9][10][11][12] . For instance, the energy density of the biaxial-oriented polypropylenes (BOPP), the best commercially available dielectric material, is ~ 2 J/cm 3 , which is significantly lower than the energy density of a typical electrochemical capacitor (i.e.…”

3D printing of anisotropic polymer nanocomposites with aligned BaTiO3 nanowires for enhanced energy density

“…[15][16][17] PVDF based nanocomposites with embedded ferroelectric ceramics such as BaTiO 3 , 18,19 Ba 1Àx Sr x TiO 3 , 20 and Pb(Zr 1Àx Ti x )O 3 21 show enhanced energy density due to the combination of the high relative permittivity from the ferroelectric ceramics and high breakdown strength from the PVDF polymer matrix. In our previous work, ceramic fillers with high aspect ratios, such as BaTiO 3 , [22][23][24] Na 0.5 Bi 0.5 TiO 3 , 25 TiO 2 @PZT, 26,27 and Na 2 Ti 3 O 7 nanowires 28 were employed to build dielectric capacitors with improved permittivity and energy density. The improvment in energy density is attributed to the high breakdown strength mainatined by low ceramic loadings and increased relative permittivity due to the high aspect ratio fillers.…”