Effects of Amphiphilic Carbonaceous Nanomaterial on the Synthesis of MnO2 and Its Energy Storage Capability as an Electrode Material for Pseudocapacitors

An amphiphilic carbonaceous material (called CP-AS) derived from coal tar pitch has been introduced to synthesize a hollow MnO2/CP-A5 hybrid on the meso- or microscale in a poly(ethylene glycol) 400-water mixture using a self-template method. In the presence of CP-AS, the MnCO3 precursors change from cubes of approximately 450 nm to spheres of approximately 300 nm, and their basic building blocks vary from two-dimensional nanosheets to nanoflakes. The derived two types of hollow MnO2 preserve the morphologies of their own precursors well and inherit the basic building blocks. The electrochemical data indicate that MnO2/CP-A5 hollow spheres exhibit not only higher specific capacitance and lower resistance, including the intrinsic resistance of the electrode, Faradaic reaction resistance, and ion-diffusion/-transport resistance, but also better electrochemical stability than MnO2 hollow cubes because of their reduced particle size, induced morphology, and modified electrode/electrolyte interface.