Facile synthesis of pseudocapacitive Mn3O4 nanoparticles for high-performance supercapacitor

Abstract In this work, a facile method to produce the ultrafine (4–14 nm) and mixed valence Mn3O4 nanoparticles from low-cost MnSiO3 (manganese silicate) particles were introduced. The best NaOH concentration in hydrothermal treatment has been determined after a series of experiments. Also, the as-synthesized Mn3O4 material with good specific capacitance has been investigated attentively at a high mass loading (∼3 mg cm−2). The particles size and the pore size distribution is found to be refined and optimized, respectively. This increased the crystallinity and the capacitive contribution in the energy process. Thereby improving the rate capability and cycling stability, which result in significant improvement of specific capacitance (401 F g−1 at 10 mV s−1). The aqueous asymmetric supercapacitor device AC//Mn3O4 with a stable working voltage window up to 2.0 V has been fabricated, and it is found to have an energy density of 40.2 W h kg−1 at 500 W kg−1 power density. This could sustain 5000 cycles galvanostatic charge/discharge with 96.9% retention.