Ccto-P(VDF-CTFE) 0-3 Composites for Energy Storage Application

ABSTRACT
Recently, there is a great need to develop a new ceramic-polymer composite which exhibits relatively high dielectric constant, high dielectric strength, low dielectric loss and high flexibility for applications ranging from electronic packaging, embedded capacitors, to energy storage [1, 2]. The electric energy density (U_e) can be calculated by the equation U_e=1/2ε₀ε_rE_b², where ε₀ is the vacuum permittivity (8.85×10^-12 F/m), ε_r is dielectric constant of composite, and E_b is dielectric breakdown field. A higher dielectric constant or dielectric strength would allow a higher energy density, are highly desirable for the dielectrics used in energy storage devices [2]. Ceramic-polymer composites have been detail studied by researchers, and most of the recent studies were focused on the PVDF-based composites.

In this experiment, the nano-sized CaCu₃Ti₄O₁₂ powder and P(VDF-CTFE) 88/12 mol.% are used for prepare composites by solution cast with high dielectric constant in previous work [3, 4]. To enhance the uniform distribution of ceramic filler in polymer matrix, the CCTO powder was firstly coated with the coupling agent 1 H, 1H, 2H, 2H Perfluorooctyltrichlorosilane, which can be used to improve the dielectric breakdown field. The coated powder was mixed with P(VDF-CTFE) in dimethyl formamide (DMF) solution then casting as thin film at 70^oC and annealed with different temperatures. The dielectric constant and dielectric strength of the composites were studied using Impedance Analyzer and H.V. Supply Amplifier/Controller respectively. The annealing effect, amount of coupling agent and temperature dependence of dielectric properties were studied for these composite films. The energy density in these nanocomposites can reach around 4.5 J/cm³ with volume fraction of CCTO around 15 vol.%, which makes them attractive for high energy density capacitors and electric energy storage devices.

REFERENCES
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