Air-plasma discharged PVDF based binary magnetoelectric composite for simultaneously enhanced energy storage and conversion efficiency

Abstract

Different nanomaterials and their modified forms are very often added into a poly(vinylidene fluoride) (PVDF) matrix in order to improve the energy storage and conversion efficiency of the system. The improvement in energy storage density caused by this secondary nanomaterial addition is most often found to be accompanied by the reduction in energy storage efficiency due to increased amounts of space charges. Here, we show that both the capacitive energy storage density and efficiency can be simultaneously improved by air-plasma discharging on the PVDF based composite system. The energy storage density and efficiency of a 5 wt. % BiFeO3 loaded PVDF film (5BF) have been found to be increased to ∼1.55 J/cm3 and ∼73%, respectively, from the values of ∼1.36 J/cm3 and 59% after air-plasma discharging. The dipole rotation caused by air-plasma discharging also helped in improving the mechanical to electrical energy conversion efficiency and magnetoelectric coupling of the studied composite system. Upon similar periodic applied stress, the pristine and air-plasma discharged 5BF film showed ∼3 and 9.6 μW/cm2 of output electrical power density with ∼13.5 and 19.2 V of open circuit output voltage, respectively. The air-plasma discharged 5BF film (5BFD) has also shown an excellent magnetoelectric coupling coefficient (α33) of ∼35 mV cm−1 Oe−1 at 1 kHz frequency of fixed AC magnetic field (∼3 Oe) and 4 kOe of DC bias field. The simultaneous improvement of all of these parameters of the studied composite system caused by air-plasma discharging proves its multifunctional applicability in a variety of real life applications.