A Mn₃O₄ nanospheres@rGO architecture with capacitive effects on high potassium storage capability

A two dimensional (2D) Mn₃O₄@rGO architecture has been investigated as an anode material for potassium-ion secondary batteries. Herein, we report the synthesis of a Mn₃O₄@rGO nanocomposite and its potassium storage properties. The strong synergistic interaction between high surface area reduced graphene oxide (rGO) sheets and Mn₃O₄ nanospheres not only enhances the potassium storage capacity but also improves the reaction kinetics by offering an increased electrode/electrolyte contact area and consequently reduces the ion/electron transport resistance. Spherical Mn₃O₄ nanospheres with a size of 30-60 nm anchored on the surface of rGO sheets deliver a high potassium storage capacity of 802 mA h g^-1 at a current density of 0.1 A g^-1 along with superior rate capability even at 10 A g^-1 (delivers 95 mA h g^-1) and cycling stability. A reversible potassium storage capacity of 635 mA h g^-1 is retained (90%) after 500 cycles even at a high current density of 0.5 A g^-1. Moreover, the spherical Mn₃O₄@rGO architecture not only offers facile potassium ion diffusion into the bulk but also contributes surface K⁺ ion storage. The obtained results demonstrate that the 2D spherical Mn₃O₄@rGO nanocomposite is a promising anode architecture for high performance KIBs.