Boosted Na-MnO supercapacitor performance via strong metal support interaction.

MnO is widely utilized as an electrode material in supercapacitors. However, overcoming challenges such as sluggish ion migration, aggregate tendency, and low conductivity is imperative for optimizing MnO-based supercapacitors. Herein, NaMnO was employed as the Mn precursor to introducing a higher concentration of small Na ions into the layer structure of δ-MnO. This elevated Na concentration fosters efficient ion migration within the MnO lattice. Moreover, Na-MnO was deposited onto Cu/graphene (Cu/G) composites. Leveraging the strong metal-support interactions (SMSI) between Cu and graphene, the resulting composite demonstrates enhanced conductivity and reduced aggregation. Combining MnO with Cu/G resulted in a conductivity of 5.78 × 10 S cm, which is significantly better than that of MnO. The composite material exhibits an exceptional electrochemical performance, boasting a specific capacitance of 655 F g at 1 A g and impressive long-term stability, retaining 95 % of its capacitance after 4000 cycles at 10 A g. Additionally, a 1.6 V asymmetric supercapacitor was assembled, featuring carbon as the anode, Cu/G/MnO as the cathode, and 1 M KOH as the electrolyte, achieving a superior specific capacitance of 75 F g at 1 A g. Cu/G/MnO//carbon demonstrates a maximum energy density of 27 Wh kg at a power density of 0.8 W kg. This study underscores a facile strategy to enhance MnO-based supercapacitors by leveraging the SMSI effect for boosted performance.