Tailoring BaTiO3-Ni0.5Co0.5Fe2O4 multiferroic composites for enhanced energy storage applications

Abstract

Multiferroic composites comprising piezoelectric and piezomagnetic phases are considered highly promising options for future memory devices, spintronic devices, energy harvesting systems, and energy storage applications. In this work, particulate composites are synthesized using piezoelectric barium titanate (BaTiO₃-BTO) and piezomagnetic nickel cobalt ferrite (Ni_0.5Co_0.5Fe₂O₄-NCFO), owing to their exceptional piezoelectric and magnetostrictive properties, respectively. Magnetic hysteresis (M − H) measurements show that the 0.2BTO-0.8NCFO (denoted as x = 0.2) composite exhibits the highest saturation magnetization (M_S∼47.7 emu/g) and remanent magnetization (M_r∼21 emu/g), which further decreases in the composites with increasing BTO weight percentage. Dielectric studies reveal a deterioration in both real and imaginary permittivities at higher frequencies, attributed to the suppression of space charge and dipolar polarization mechanisms. Electrochemical analysis shows the battery-type behaviour of the prepared samples. Notably, the x = 0.8 composite achieves a higher specific capacitance (C_s) of ∼397 F/g and a specific capacity of ∼179 C/g at 0.25 A/g. Also, it maintains a capacity retention of about ∼69 % after 10,000 charge-discharge cycles. Further, the asymmetric device was constructed using x = 0.8 composite and activated carbon as cathode and anode respectively, which delivers a high energy density of 8 Wh/kg at a power density of 350 W/kg. These findings indicate the potential of BTO-NCFO multiferroic composites for applications in energy storage systems.