Excellent Energy Storage of PVTC-Based Composites at Low Electric Field by Filling with Core-Shell CCTO@SiO2 Nanoparticles

Polymer film has a wide range of applications in power equipment because of its excellent energy storage characteristics. Here, an innovative approach of ferroelectric polymer composites with core-shell structured inorganic fillers is proposed. In this paper, the CaCu
3
Ti
4
O
12
(CCTO) nanoparticles are coated by SiO
2
as inorganic fillers and dispersed in P(VDF-TrFE-CFE) (PVTC). The CCTO-PVTC and $\mathrm{CCTO} \text{@} \mathrm{SiO}_{2}-\mathrm{PVTC}$ nanocomposites are fabricated by solution casting technique. In particular, compared with the CCTO-PVTC composites, the energy storage properties of the $\mathrm{CCTO} \text{@} \mathrm{SiO}_{2}-\mathrm{PVTC}$ films are improved at given content. In addition, the thin SiO
2
layer can not only improve the interfacial compatibility between CCTO and polymer matrix, but also delay the premature interfacial breakdown caused by electric field concentration. The composite filled with 1 wt % $\mathrm{CCTO} \text{@} \mathrm{SiO}_{2}$ nanoparticles show an energy density of 6.9 J / $\mathrm{cm}^{3}$ and an excellent efficiency of 50 % under the electric field of 310 kV/mm.