One-pot synthesis of MnX₂O₄(X = Co, Ni)/graphite nanoflakes composites as high-performance supercapacitor electrodes

We put forward a facile one-pot hydrothermal strategy to synthesize the MnX₂O₄(X = Co, Ni) spinel/graphite nanoflakes (GNF) composites. Note that the physical exfoliation toward GNF frees the method from the complex and expensive conventional chemical treatments. The obtained MnCo₂O₄/GNF (MCO/GNF) and MnNi₂O₄/GNF (MNO/GNF) exhibit high specific capacitance (1712 F g⁻¹ for MCO/GNF and 1622 F g⁻¹ for MNO/GNF at 1 A g⁻¹) and good cycling performance (almost 80 % capacitance retention after 3500 cycles at 5 A g⁻¹ for both MCO/GNF and MNO/GNF). Furthermore, the asymmetric supercapacitor (ASC) with MCO/GNF or MNO/GNF as positive electrode and rGO as the negative electrode is assembled. The optimized ASC is able to show high energy density up to 22.5 Wh kg⁻¹. Together with the facile synthetic strategy, such good electrochemical performance may promote the spreading of the next-generation energy storage electrodes.