Facile strategy of using conductive additive supported NaMnPO4 nanoparticles for delivering high performance Na-ion supercapacitors

• A facile synthesis route for stable, single phase NaMnPO 4 (NaMP) nanoparticles. • Incorporation of conducting additives to improve the electrochemical activity. • More than 2-fold increment in specific capacitance for optimum PANi-NaMP composite. • Improved cycling stability after polymer incorporation. • 59 F g- 1 capacitance with energy density of 26.5 W h kg −1 for PANi-NaMP//AC device. A novel strategy of incorporating conducting additive to enhance the performance of NaMnPO 4 -based Na-ion supercapacitors is presented. It is observed that forming composite with a conducting polymer, leads to nearly two-fold increment in the specific capacitance of a Na-ion based system. The higher conductivity, fast Faradaic response alongside with greater number of ion transport channels lead to this improvement. Here, the best performance is obtained at an optimized polyaniline (PANi) percentage of 30 wt%, where a specific capacitance of 201 F g −1 at 1 A g −1 current density was observed. This is more than twice the value obtained by pure NaMnPO 4 . The fabricated supercapacitors also deliver 26.5 W h kg −1 specific energy and high cycling stability.