Electrochemical performance and large positive–negative magnetodielectric coupling in iron chromite spinels

•Current work is one of its kind study suggesting a material that can be used to fabricate a device that can simultaneously store memory and energy.•Low cost sol–gel method is used to synthesize iron chromite nanocrystals by varying Fe/Cr ratio.•Spinel phase i.e. FeCr2O4 is observed at Fe/Cr ratios of 0.45, 0.6 and 0.65.•Magneto dielectric (MD) studies confirm positive MD constant at 0.45, 0.6 & 0.65 Fe/Cr ratios.•The galvanostatic charging/discharging behavior shows capacitive behavior of FeCr2O4 samples.•The electrochemical results suggest that synthesized nanocrystals have potential for energy storage system.